ABSTRACT. Professor Tich Thien Truong Dean, Faculty of Applied Science, Ho Chi Minh City University of Technology - VNUHCM, Vietnam

ABSTRACT. GREETINGS FROM RECTOR BOARD Representative of Rector Board, Ho Chi Minh City University of Technology - VNUHCM, Vietnam

ABSTRACT. KEYNOTE SPEECH 1

ABSTRACT. The general report presents several new contributions on numerical methods for fracture mechanics given by Computational Mechanics & Optimization (CMO), a research group from Engineering Mechanics division, Faculty of Applied Science, Ho Chi Minh City University of Technology, Vietnam National University – HCM. In recent years, some improvements in extended mesh-based and meshless methods have been proposed for fracture analyses in linear isotropic, orthotropic, functionally graded materials, and nonlinear hyper-elastic materials. Several types of crack problems have been investigated including quasi-static crack propagation, dynamic behavior of crack, thermal-mechanical crack behavior, and crack analysis in large deformation problems. The main contributions of the studies are improvements in numerical crack modeling and enhancements for computing performance. Most of the contributions are published in high-quality journals of the communities of fracture analysis and computational engineering.

ABSTRACT. During the time of isolation due to the COVID-19 pandemic, implementation of experimental research activities of the Biomedical Engineering training program at the Ho Chi Minh City University of Technology – VNUHCM has faced many difficulties for the following reasons:

- Undergraduate and graduate students cannot come to the laboratory to perform experimental measurements collecting data to evaluate expected projects.

- Equipment research groups could not build test models inability to purchase spare parts and supplies, and manufacture prototype devices.

- Clinical application research groups cannot approach hospitals and medical enterprises to collect expected clinical data and process statistics.

Therefore, research activities serving projects, graduation theses, student research programs, etc. have been considerably delayed, affecting the progress towards achieving the training program goals, especially for students in their final years of the training program.

Faced with the mentioned situation, the Biomedical Engineering Department has shifted research topics to use computational techniques and take advantage of online biomedical databases to implement alternative studies as follows:

- Apply artificial neural networks and machine learning techniques to handle biomedical image processing tasks such as segmentation, recognition, survival prediction; investigate biomedical and psychological behaviors; enhance processing biosignals, etc.

- Approach to simulation method of molecular dynamics simulating some pathogen issues of SARS-CoV virus.

- Simulate multispectral optical distribution of some biological objects to investigate applications in human health screening and food safety testing.

- Experimental study of the algorithm for improvement for real-time processing of biomedical image and signal for mobile devices; for statistical evaluation of the performance of medical devices.

The above orientations completely match the expected output standards of the biomedical engineering training program and contribute to opening up new research directions, demonstrating the readiness and adaptability of students as well as instructors and researchers in an effort to achieve the best quality of research projects adequately under permissible conditions.

ABSTRACT. Enhancing international collaboration is an indispensable strategy for today’s cooperation model and, due to the COVID-19 pandemic, the important role of International collaboration has been fully recognized. The National Cheng Kung University (NCKU) always endorses the latest trends, with the mission of spreading knowledge and furthering connections with other countries in the world. NCKU works as a “golden bridge” to connect Southeast Asia, Europe, and other areas together, to create values, and to contribute to society. National Cheng Kung University Overseas Hub in Vietnam (NCKU OH) was established in 2017 and has created a “diamond” partnership encompassing Vietnamese universities, Taiwanese companies, local enterprises, and other institutes around the world. The aim of NCKU OH focus in: International Education through the short-term courses implemented locally/virtually; Joint research Project to introduce amazing research’s result and increase the connection between NCKU and the partners as well as towards building international and interdisciplinary research groups to solve the real-world regional and global challenges; Academy-Industry cooperation through the Interdisciplinary talent cultivation in the online job fair and the Young talent cultivation through the webinar with the join in of the stakeholders from different organizations. This speech represents one of the greatest global transformations ever and will open up new ways of international collaboration.

ABSTRACT. The quasiparticle viewpoints, mediating all interactions within the intrinsic and external fields are available in characterizing the elastic and/or inelastic scattering processes. The composite quasiparticles consist of identical or distinct ones by the unusual interactions among them; that is, they cover electrons, phonons, photons, and their composites, being greatly diversified through the various cases. Obviously, how to characterize the multi-component quasiparticle phenomena is worthy of the near-future systematic investigations. In this talk, I will present the close relations among the first-principles simulations and the phenomenological models which are very useful in thoroughly exploring the physical, chemical, and material phenomena, which are delicately developed under a grand quasiparticle framework. This strategy has been successfully proposed and done for a lot of emergent 3D/2D/1D/0D condensed-matter systems, binary/ternary/quaternary semiconductor compounds, and green energy materials [e.g., ion-based batteries].

ABSTRACT. Distributed machine learning is a hot research topic recently, owing to the development and success of deep learning techniques which require huge amount of data, and computation/communication resources. In this talk I will survey recent machine learning algorithms operating on distributed data, from both theoretical and practical aspects. On the theoretical side, I focus on the mathematical convergence; while on the practical side, I report experimental results over large benchmark datasets. Issues such as communication efficiency and data privacy, and corresponding solutions are also presented.

ABSTRACT. In this talk, we would like to introduce machine learning from the mathematical and statistical point of views. Starting from classical statistics and mathematics, we will briefly discuss some of the core ideas of machine learning as well as some mainstream lines of research and future directions. Finally, a wide variety of applications are also discussed. This presentation aims at mathematicians and statisticians who would like to extend their work with techniques from machine learning.

ABSTRACT. This study has been done in cooperation with the automotive supplier Valeo. In automotive industry, client needs evolve quickly in a competitiveness context, particularly, regarding the fan involved in the engine cooling module. The practitioners are asked to propose “optimal” new fans in short times. Unfortunately, each evaluation of the underlying computer code may be expensive whence the need of approximated models and specific, parsimonious, and efficient global optimization strategies. In this paper, we propose to use the Kriging interpolation combined with the expected improvement algorithm to provide new fan designs with high performances in terms of efficiency. As far as we know, such a use of Kriging interpolation together with the expected improvement methodology is unique in an industrial context and provide really promising results.

ABSTRACT. A two-class mixture model, where the density of one of the components is known, is considered. We address the issue of the nonparametric adaptive estimation of the unknown probability density of the second component. We propose a randomly weighted kernel estimator with a fully data-driven bandwidth selection method, in the spirit of the Goldenshluger and Lepski method. An oracle-type inequality for the pointwise quadratic risk is derived as well as convergence rates over Holder smoothness classes. The theoretical results are illustrated by numerical simulations.

ABSTRACT. A careful examination of how long it took countries/territories to reach the tipping point of being classified as a COVID high-risk level could provide insight into the global severity of COVID epidemics. Furthermore, it contributes some experience in dealing with ongoing outbreaks. Given publicly data of 222 countries and independent territories, we used the stratified Cox model to analyze the time-to-event of countries/territories while taking demographic factors into consideration, particularly the time-varying impacts of the vaccination rate and the stringency index.

ABSTRACT. This article proposes a new modified SIR (abbreviated form of Susceptible, Infectious, Recovered) model which combines divers practical delay parameters with expanded list of variables leading to a more accurate description of COVID-19 real time data. In fact, delay differential equation is used instead of ordinary differential equation, and some new variables of importance as first dose and second dose vaccinated individuals are added to the classical SIR list. The reliability of that newly suggested delayed SIR model is established by using processed data of HoChiMinh City from 06 July 2021 to 01 October 2021 when the biggest city in Vietnam was stricly socialy distanced as The Government Sixteen Law was applied. Several introduced delay parameters as delay period for incubation, also as for effectiveness of antibodies inside vaccinated individuals transform the model into more realistic and more approriate investigation of the COVID-19 pandemic study. Some exponential stability criteria is given through matrix measure of the linear dynamic delayed differential system. The evaluation work of important parameters as the reproductive number R0 and divers rates representing transition process from one group of individuals to other group like Susceptible individuals to Infectious group is perfomed by using reliable and appropriate statistical methods. The numerical simulations is done in Matlab, where method of steps is used to assure effects of lags also propagation of discontinuities together with defect (residual) are under control.

ABSTRACT. speed, from which many urgent problems have been realized by policy makers as well as scientists. The concentration of human activities on a relatively small area imposes large pressures on the environment and can lead to serious environmental problems, including air pollution. This note introduces few statistical modeling approaches recently developed, earliest since the 60s of the last century, including classic spatial statistical models, e.g. kriging and specifically its extension to the multivariate case-cokriging. We start with kriging-based spatial models having only one unbiased estimator, then propose a bi-objective optimization for computing optimal co-kriging model with two unbiased estimators of the most critical pollutants. Then we discuss Bayesian inference, a major methodology in statistical science and data analytics., and discuss how to incorporate it with co-kriging techniques. The data-analytics based methods of this note being illustrated via a case study - with air pollution data of seven pollutants monitored in Saigon - would hopefully convince policy makers in the sectors of environment management and urban development that reliably statistical prediction of pollutant concentration and quantifying causal relationships between climate-centric explanatory covariates and the human mortality are essential in the studies of air pollution, and broader, of environmental epidemiology.

ABSTRACT. In this talk, we present the amplitude dynamics of n-dimensional (nD) solitons in a fast collision under a framework of coupled perturbed (n+1)D nonlinear Schr\"odinger equations with a saturable nonlinearity and competing nonlinearities for n=2,3. We propose a new perturbative method which is based on the calculations on the energy balance of perturbed solitons and the analysis of the collision-induced change in the envelope of the perturbed soliton. These results measure the abrupt energy dropdown due to a fast collision of two optical beams (n=2) or two light bullets (n=3) in perturbed nonlinear media.

ABSTRACT. Uncertainty Principles are at the foundation of quantum mechanics. In this talk, we discuss the sharp constants and optimizers of the uncertainty principles and the L2-Caffarelli-Kohn-Nirenberg inequalities for scalar functions as well as for curl-free vector fields. We also address quantitative stability results for the Heisenberg-Pauli-Weyl uncertainty principle. This is joint work with Cristian Cazacu and Joshua Flynn.

ABSTRACT. A common representation of a three dimensional object in computer applications, such as graphics and design, is in the form of a triangular mesh. In many instances, individual or groups of triangles in such representation need to satisfy spatial constraints that are imposed either by observation from the real world, or by concrete design specifications of the object. In this talk, we model various geometric constraints as convex sets in Euclidean spaces, and find the corresponding projections in closed forms. We then use first-order splitting methods to find optimal solutions.

ABSTRACT. In this talk, we study the model of continuous neural network and its application in the problem of data fitting for continuous processes. After that, we present the need of using the technique of nonsmooth analysis in this study. As s main contribution, we construct the back-propagation technique for one general class of continuous neural ordinary differential equations.

ABSTRACT. We consider a general vector optimization problem with inequality constraints, a very popular and important model with a long research history in optimization. The generality of setting is mainly expressed in the following three factors. The underlying spaces being linear spaces without topology (except the decision space being additionally equipped with this structure in some results). The ``orderings" in both objective and constraint spaces are defined by arbitrary nonempty sets (not necessarily convex cones). The problem data are nonsmooth mappings, i.e., they are not Fréchet differentiable. For this problem, we investigate optimality conditions and Wolfe and Mond-Weir duality properties, which lie at the heart of optimization theory. These results are established for the three main and typical optimal solutions: (Pareto) minimal, weak minimal, and strong minimal solutions in both local and global considerations. We define a type of Gateaux variation to play the role of a derivative. For optimality conditions, we introduce the concepts of on-set differentiable quasiconvexity for global solutions and sequential differentiable quasiconvexity for local ones. Furthermore, each of them is separated into type 1 for sufficient optimality conditions and type 2 for necessary ones. After obtaining optimality conditions, we apply them to derive weak and strong duality relations for the above types of solutions following our duality schemes of the Wolfe and Mon-Weir types. Due to the complexity of the research subject: considerations of duality are different from that of optimality conditions, we have to design two more appropriate types of generalized quasiconvexity: scalar quasiconvexity for the weak solution and scalar strict convexity for the Pareto solution. So all the results are in terms of the aforementioned Gateaux variation and various types of generalized quasiconvexity. Our results are remarkably different from the related known ones with some clear advantages in particular cases of applications.

ABSTRACT. In this paper some new notions of generalized convexity for real-valued functions. First, we propose the terminology “sequential quasiconvexity”. The main idea is replacing convex domain or whole line segments, used in the known definitions of generalized quasiconvexity, by a sequence of points tending to a point interest. These properties we show that the conditions of these properties are relaxed. The main results of this research are “local max to global min”, “local max to global min” and optimality conditions. In the second application, we consider the multi-objective optimization problem, denoted by (MP). In this problem we show the relationship between optimal solutions with sequential subdifferentially Clarke quasiconvex.

ABSTRACT. This report provides some results on the approximate efficiency of a robust nonsmooth semi-infinite objective optimization problem associated with data uncertainty. Karush-Kuhn-Tucker type necessary conditions and sufficient conditions for approximate Pareto solutions of such a problem are derived. To this aim, Abadie and Pshenichnyi-Levin-Valadire constraint qualifications are proposed. In addition, we state a dual problem formulated in an approximate form to the reference problem and explore duality relations between them. Finally, we employ the obtained results to present linear robust programming. Examples are provided for analyzing and illustrating our results.

ABSTRACT. Introduction: As the demand of bone defect treatment grows, natural bone graft cannot be fulfilled the order. Therefore, development of artificial bone graft is essential for biomedical application. In this study, the feasibility of bioactive cockle shell Aragonite/ Gypsum composite as bone cement for bone repair has been demonstrated. It is meaningful to use the by-products from food industry such as cockle shell for preparation of valuable biomedical materials. Method: Bioactive cockle shell Aragonite/Gypsum composite as bone cement was prepared using cockle shell and Calcium Sulfate Hemihydrate (CaSO4. 0.5H2O) powder mixtures with different weight ratios. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscope (SEM) were used to characterize phase composition and structure. Mechanical strength was evaluated in term of Diametral Tensile Strength (DTS) and In vitro bioactivity was investigated using Simulated Body Fluid (SBF) solution. Results: The results indicated that cockle shell Aragonite/Gypsum composite as bone cement is bioactive and its properties depend on weight mixing ratios. As a conclusion, cockle shell Aragonite/Gypsum composite is ideal candidate to reconstruct bone defect due to its bioactivity and abundant supply.

ABSTRACT. In dentistry, X-ray method is considered the gold standard for identifying structural damage in teeth. However, X-rays not only have unwanted effects on the patient’s health but also have failed in detecting small and early lesions due to the low sensitivity to early lesions. In order to overcome that disadvantage, the infrared and fluoresence techniques have been developed in recent years. Many studies have showed that the sound enamel is nearly transparent under near infrared light due to its low absorption and scattering coefficients to near infrared light [1-2]. On the contrary, the damaged enamel with the change in optical properties due to its low mineral density appears darker compared to sound teeth on near infrared image at 780 nm-1310 nm [2-3]. In addition, the fluorescence technique is able to detect the presence of bacteria causing tooth decay on the enamel surface by studying the enamel’s luminescent property. The sound enamel containing different minerals emits blue light stimulated by near ultraviolet or purple light wherares porphyrins presenting in plaque or cavities fluoresce red light. Therefore, the combination of fluorescence and infrared techniques helps not only detect tooth lesions at an early stage, but also track and predict the odd of lesions happening even when no symptom has showed up yet. In this study, the two optical systems using 850-nm LEDs for infrared imaging and 365-nm LEDs for luminescence imaging were applied to identify in vitro different types of lesions on the tooth samples. The evaluation of the effectiveness of the diagnostic results obtained by the infrared combined with fluoresence technique in comparison with clinical observation and X-rays was conducted through the calculation of Cohen's Kappa coefficient using the Statistical Package for the Social Sciences (SPSS) programme.

ABSTRACT. Vital signs are the body's signals that indicate the state of living. In particular, we can detect many pathological risks from the feedback data when monitoring vital signals continuously and in real time. This research was performed by creating a compact device model with a sensor that received PPG signals from wavelengths 660nm and 880nm to calculate heart rate and SpO2; received NIR signals to calculate body temperature. Data obtained from the sensor will be transferred in real time and displayed on the Android mobile app. Presently, the receiving and transmitting model is completed and the received signals are relatively accurated. The team's direction is to create wearables that monitor vital signals accurately, in real time and for user convenience. The device will also be improved to increase the clinical accuracy of the received signal to make appropriate diagnoses and treatments.

ABSTRACT. Glioblastoma (GBM) is the most common and aggressive malignant brain tumor. It grows rapidly, is devastating, often leads to high mortality shortly after diagnosis. Accurate prediction of patients' overall survival is crucial for diagnosing, identifying risk factors, and planning treatment. This study conducted the tumor grade patient's overall survival prediction based on the Pyradiomics method for feature extraction from segmented tumor regions of MRI images (provided by the BRATS 2019 challenge). Then, we applied recursive feature elimination (RFE) and F-Test to select potent features. Based on 28 the features selected, we trained a multilayer perceptron model. The dataset is labeled into three classes of survivors: short- survivors (<300 days), mid- survivors (>=300 days to <=450 days), and long- survivors (>450 days). The accuracy of the survival prediction model for the training set, validation set, the testing set: 75%, 68%, and 77%.

ABSTRACT. Nowadays, applications like web app and mobile app have been really useful in medical field. These apps help doctors and medical experts diagnose and treat diseases more easily and accurately, especially cancer. Fighting cancer is one of the most important medical tasks and we need the assistance from information technology to do that. In this paper, we present our web app which can show, preprocess DICOM files and segment, classify brain tumor. This app can help users save time and increase accuracy in diagnostic process. It includes image preprocessing tools such as denoising, improving contrast tools, canny edge detection and drawing tools to segment tumor. Tumor classification is performed automatically using morphological features (area, perimeter, compactness and elliptical fourier coefficients) and statistical features (mean, variance, skewness, kurtosis, entropy and grey level co-occurrence matrix features) to distinguish between high-grade gliomas (HGGs) and lower-grade gliomas (LGGs) from MRI brain images. Classification model we used in this research is Multilayer Perceptron (MLP) and Random Forest (RF) with the dataset BRATS 2019.

ABSTRACT. In the industrial context, there are key factors that directly affect the system’s efficiency. Higher demands for both quantity and quality in today’s market call for constant research and development of technologies for automating production and quality control. Machine vision is a solution to increase speed and accuracy in defect detection. However, applications from machine vision are only effective if there is good data input. This is the reason why a machine vision system, needs high-quality input images from a well-designed illumination system. These illumination systems are designed to highlight faults in products. Therefore, the images obtained will provide optimized data for easier image processing thus directly increase the processing speed, accuracy, and overall system performance. To achieve this goal, this paper presents a few approaches to enhance and optimize images by implements illumination techniques into a miniature model of pharmaceutical bottle assembly line using machine vision as the inspector block. In this paper, we will evaluate the critical needs of using customize illumination system for quality inspection on an assembly line.

ABSTRACT. Noise cancellation technology is a promising technology aimed at reducing unwanted ambient sound. In this paper, we developed a prototype device using active noise cancellation (ANC) method. This method uses aural overlap and destructive interference to target and attenuates background noise. There are some research groups and carmakers who have successfully built ANC models in cars. However, the cost of these models is very high. The research team will inherit advantages from existing models, thereby designing the ANC system in cars with minimal cost, weight, and energy consumption to reduce the unwanted sounds affecting the driver. The achieved experimental and simulation results with engine noise show the effectiveness of the proposed device.

ABSTRACT. Applying laser technology to the growth of plants to limit the use of chemical fertilizers is an interesting topic in agriculture. The main idea is to preserve the environment, ensuring product quality while still achieving high productivity, we decided to carry out this research project, to investigate the effect of the low-level laser (the wavelengths 532nm, 850nm, and 940nm) on stems and leaf development. It is expected that with these research results, the implementation method will be widely disseminated in the high agricultural sector, coming closer to farmers. Moreover, the results of the analysis of the composition of bitter melon stems and leaves will be applied in medical treatment (such as diabetes, wound treatment, anti-oxidation, anti-bacteria ...)

ABSTRACT. Nowadays, science and technology are developing more and more, people have made great signs of progress in many fields, realizing things that previously thought impossible. In the world in general and in Vietnam in particular, the pace of life of people in big cities is increasing day by day. The fields necessary for life all require certain progress in response to the changing world and the most concerning factor today is human health. The application of new technologies for the initial diagnosis of the patient reduces the risks, diagnoses the underlying disease, and meets the main requirements of fast, concise, and accuracy, increasing the chances of a cure. patients before emergencies. This research is highly applicable, building a system that allows monitoring and observation of human health easily and conveniently. Specifically, building a system to check some basic vital signs such as saturation of peripheral oxygen (SPO2), heart rate (HR), and body temperature; ensure immediate detection of health incidents so that they can provide timely treatment, avoiding unfortunate situations. To meet the requirements, it is necessary to understand the meaning of the signal parameters, so that it is possible to design and program the appropriate methods to minimize measurement errors. The machine uses data from two sensors: a saturation of peripheral oxygen combined with a heart rate measurement sensor (MAX30102) and a non-contact infrared temperature sensor (MLX90614) transmitted to the Arduino UNO R3 board to process and analyze, then display accurate results on the OLED screen to help users get the fastest figures.

ABSTRACT. Shortages of medical equipment are insufficient to meet the worldwide pandemic. The breast pump is easy to buy and cheaper can turn into a ventilator to solve the pressing problem. Ease of portability is also one of its advantages.

ABSTRACT. The recent ongoing pandemic coronavirus disease 2019 (COVID-19) is growing increasingly out of control globally, posing a severe threat to human health. The 2019 Coronavirus Disease (COVID-19) has wreaked havoc on the healthcare system, with the fatality rate steadily rising owing to a lack of vital equipment, particularly ventilators, which have failed to meet the urgent demands of patients with severe acute respiratory failure. We designed and developed a simple, portable, and low-cost mechanical ventilator in this study to handle supply chain interruptions rapidly. The device operates with the continuous, emergency, closed modes by controlling the adjustable pressure by doctors to provide safety and efficiency. The employment of mechanics to regulate pressure has the potential to harm the lungs. Adjusting the gadget to avoid excessive pressure, which is a result of too much energy. By integrating pressure sensors linked to the respiratory limbs controlled by the algorithm, we created a technique to monitor the health of a patient's lungs to limit the danger of unexpected events in lung pressure. The Raspberry Pi is utilized to maximize the cheap cost of functioning as the device's brain to aid regulate, control mechanics, pressure, and sensors. We provide two primary topics in several of these journals: creating a patient lung pressure monitoring technique that helps regulate the system to run safely and reliably, and designing low-cost mechanical ventilator systems for patients with COVID-19.

ABSTRACT. Low back pain is a common disease. A common cause of this problem is a herniated disc in the lumbar spine. Lumbar disc herniation represents the displacement of the disc (annular fibrosis or medullary nuclei). While most cases, the pain will disappear in a few days to a few weeks; however, it can last for three months or more. Detection and diagnosis are the two most important tasks in a computer-aided diagnostic system. In this article, we use images taken from the results of the MRI imaging of the patient. Through the use of image inversion to highlight the position of degenerative discs. This result wishes to provide a simple and inexpensive diagnostic image processing method to help doctors quickly determine the degree of disc herniation, the status of lumbar discs, they can give the appropriate treatment to the patient.

ABSTRACT. Along with the evolution of society, the epidemic is also becoming more and more complicated and dangerous, especially the current situation in Vietnam as well as the world, the problem of overcoming the epidemic caused by a new strain of virus Sars-Cov-2 19, the consequences it causes are a huge problem of disease prevention and treatment that has not yet been solved for humanity. Finding vaccines to prevent as well as cure diseases and bring vaccines to all those who need them quickly while still ensuring the most effective quality is still a very necessary issue today. If vaccines are not stored properly and up to standards, the pharmacokinetics as well as preventive and curative effects of vaccines are reduced or lost, or post-vaccination complications are more unpredictable. Vaccine storage device have many different types, but mainly use refrigeration technology with refrigerants, with compressors operating at AC voltage. The transportation of vaccines to the place of use is usually by insulated boxes with ready-made frozen ice bags, the number of ice bags will occupy a large volume in the box, reducing the amount of vaccine needed for users, the temperature in the box is not controlled good because it depends on the temperature of the ice bags. We research and manufacture a portable storage cabinet using Peltier technology, with a temperature control unit and using batteries to operate the device. The cabinet is designed with a capacity of 4 liters, 300 mm high, 200 mm wide, 350 mm long with a weight of 2 kg, convenient to carry when moving, the screen displays the temperature and battery capacity. The allowed temperature is from minus 8 degrees Celsius to 4 degrees Celsius, the temperature warning amplitude is 2 degrees. The battery lasts for 4 hours, has a battery charger and can be charged and used at the same time.

ABSTRACT. According to the results given by the researchers, fossil energy sources will be exhausted in the future, besides the problem of environmental pollution, finding a clean energy source to replace is necessary. Renewable energy is useful energy that is collected from renewable resources, which are naturally replenished on a human timescale, including carbon neutral sources like sunlight, wind, rain, tides, waves, and geothermal heat. To collect the energy from ocean, it requires devices for converting energy from waves into electricity. There are many designs offered, although the shapes are different, they are mainly based on the principle of oscillation of the water column. The oscillating water column device is mainly made of metal or concrete, has at least one opening to the sea, one to the atmosphere, under the action of waves, the pressure inside the device changes to rotate the turbine, thereby generating electricity from the turbine's mechanical energy. This paper presents the initial results obtained during the research and testing of the wave energy converter. Based on the results of structural analysis and computational fluid dynamics, the laboratory-scale wave energy equipment was built to simulate the vertical direction of ocean waves. The research results show that the equipment is completely suitable for the actual conditions of Vietnam's sea.

ABSTRACT. Hyper-elastic materials are special elastic material that the stress can be derived by the strain energy density function. The most attractive property of these rubber-like materials is their ability to undergo large strains with small loads and recover their initial shape after unloading. Hyper-elastic materials are widely used in engineering such as tire, elastomeric bearing pad, belt drives, rail pad and so on. Due to the large strain state in most of application of this type of material, the behavior of hyper-elastic is often considered in finite deformation analysis. In comparison with linear material, analysis for hyper-elastic material which have nonlinearities is more complicated because both material nonlinearity and geometric nonlinearity should be considered. Along with the development of computer and numerical methods, the finite element method (FEM) is known as a powerful numerical computation tool that can helps to solve engineering problems in many fields such as structural, thermal, electronic, and biomedical analyses. Actually, most of practical engineering problems appear in three-dimensional (3D) state, especially in nonlinear analyses. So, the development for an effective numerical method for 3D nonlinear problems is very necessary. In this study, a finite element approach with 8-node hexahedron element is presented for analyses of large deformation problems of hyper-elastic material. The compressible neo-Hookean is used as the constitutive model for 3D hyper-elastic problems and the total Lagrange formulation is applied for the discretization of large deformation problems. To obtain the nonlinear solutions, the standard Newton-Raphson algorithm with constant load step is chosen as the iteration method. The computing programs are built with Matlab language. To verify the accuracy of the present approach, the obtained results are compared with the reference solutions given by Ansys program.

ABSTRACT. In this study, numerical computation is used to develop a physical model representing all important features of the Autonomous Underwater Vehicle's (AUV) shape using the finite element methods. Because the shape of the AUV is an essential factor in determining the application and the vehicle's capability, investigating the effect of the environment on this profile is needed. This paper illustrates using Computational Fluid Dynamics (CFD) to investigate the effect of fluid flow on the AUV's profile at different velocities. The results obtained from the numerical computation demonstrate some of the hydrodynamic values of the AUV's shape, such as drag force and stress. It is necessary for optimizing the design of an AUV. When the AUV moves, the maximum pressure occurs at the nose of an AUV.

ABSTRACT. Hyperelastic materials are the special materials which possess the nonlinear material property. In these materials, the stress-strain relation is derived from the strain energy density function. An interesting property of these materials like rubber is the ability of elastic response when it is subjected to large deformations. That means when the load is removed, the material can easily retain the initial configuration. In addition, they also have some excellent mechanical properties like good tear and abrasion resistance, flexibility at room temperature. So hyperelastic materials are widely used in the industry. Due to this reason, it is needed to take a careful look about these materials, especially in the field of mechanical behavior. Because hyperelastic materials usually work under large deformation for almost cases, their behavior is often considered in highly nonlinear elastic state. To simulate the nonlinear response of mechanical behavior, numerical methods are widely used over the years. One of the popular methods in the field of computational mechanics is finite element methods. This method has been applied successfully to find the solutions of complex problems like structure, fluid, heat and so on. But finite element methods and other mesh-based methods also have a disadvantage that is the existence of the mesh of elements. To overcome this drawback, meshless methods have been developed to remove the dependence of the nodal mesh. In this paper, a meshless radial point interpolation method is presented for hyperelastic bodies with compressible and nearly-incompressible states. The weak form is obtained from the principle of minimum potential energy and the analysis of finite deformation of nonlinear behavior is performed under total Lagrange formulation. Radial point interpolation method shape functions are employed to approximate field nodes and derivatives. Due to possessing the Kronecker delta function properties, the boundary conditions are imposed directly in the proposed method. Moreover, this method also show its advantage for nonlinear analysis, especially when the large deformation is considered and the highly-distorted nodal mesh is inherent in the structure. The efficiency and reliability of the proposed method are demonstrated through numerical examples in which the obtained results are compared with the reference solution.

ABSTRACT. Nowadays, thanks to the rapid development of orthopedic technology, many types of orthopedics have been created to help patients with disabilities. Orthopedic ankle-foot surgery (AFO) is one of the most common prescriptions for orthopedic lower extremities. They are typically designed to cover most of the patient's injured limbs, from the foot to below the knee. The design can be flexibly adjusted to suit the limbs of each patient. AFOs are usually made with hot thermoplastics and are used to combat traumatic transmission: weakness, joint instability and high muscle tone. Drop foot is a term used to describe the inability to lift a leg due to reduced muscle activity or a lack of activity around the ankle. The main causes of foot drop are nerve damage, stroke, spastic paralysis, and multiple sclerosis. There are two common complications of foot drop. First, its patients cannot control the falling of their foot after heel strike, thus, it slaps the bottom on every step. This is often referred to as a kick to the foot. The second problem is the inability to free the toes during the rotation. This pulls the patient's toes to the ground during the swing. For this reason, AFO was created to help patients with foot drop overcome the aforementioned phenomena. In fact, AFO has two important factors: rotational stiffness and durability, which have not been widely studied. This study presents the stiffness properties of plastic ankle insoles (AFOs) through finite element modeling. This study begins with the modeling and prediction of the nonlinear behavior of AFOs.

Large strain effects and non-linear materials are included in the analysis for accurate results. Therefore, the finite element method must be applied to all models to determine the relationship between AFO shear position and rotational stiffness. Because the structure is used in the range of repetitive loads, AFO performs fatigue analysis to find the optimum thickness to meet the fatigue strength. The finite element method is a reliable and efficient alternative for analyzing the behavior and fatigue resistance of AFO designs, as simulation and empirical results are nearly possible.

ABSTRACT. So far, there are various methods of fabrication (for example molding, machining, folding, welding and so forth) applied in modern industries and manufacture, which contributes significantly to the increasingly sophisticated demands of businesses. Among those methods, welding has been proving its dominance position thanks to the effectiveness and conveniences which are brought about. The application of welding is diverse, ranging from manufacturing pressure vessels, oil/ gas conveying pipelines or bonding separate structures to repairs of damages on different systems. In the past, in case manufacturers would like to figure out the appropriate heat source and post – welding residual stress, it was practical experiments that were chosen to carry out the inspection. However, time has changed. In the era of 4.0 technology, simulation softwares have recently been in charge of such experiments thanks to their diversity of application and friendly–to–user interface.  Moreover, those softwares are also functioned to be compatible with a wide range of CAD ones, which enables users to import the models of complex structures into simulation programs. Hence, it is definitely feasible to simulate the welding process in order to determine the values of heat source temperature and post–welding residual stress as well as distortion. In this paper, the procedure of welding two separate vessel with thin wall thickness shall be conducted. The thermal conduction is recorded continuously over the traveling time of weld torch whilst residual stress is determined shortly after the welding completion. Furthermore, the residual stress will also be imported into the strength–testing simulation to decide on whether the welded structure can be sustain its operation conditions. The model of the welding problem is referred mainly to an article with the same topic which was published on a scientific journal. The analysis results shall be compared with those in the article respectively.

ABSTRACT. Nosocomial infections, particularly postoperative infections, are common following surgery due to various risk factors that are contributing like age, duration of operation, number of persons in the operating theatre, the general condition of the operating room... The nosocomial infections prolonged the lengths of hospitalization, developed multi-organ dysfunction, and increased mortality. The conventional laminar airflow systems in operating required huge installation and renovation costs. It is not suitable for the Low-Middle Income Countries. This paper presents research on the view toward the realization of a mobile laminar airflow system for preventing the contamination of airborne pathogens by protecting the surgical site area as well as the instrument table at a low cost. Simulations with computational fluid dynamics (CFD) were conducted to optimizing system design. The simulation results were examined and evaluated in this paper. With this proposed laminar airflow system, sterile conditions could be created immediately wherever you need them.

ABSTRACT. Nowadays in the construction of modem buildings, it is necessary to accommodate pipes and ducts necessary services, such as air conditioning, water supply, sewerage, electricity, computer networks and telephone networks. Cellular members – steel I‐shaped structural elements with circular web openings at regular intervals – have been used as beams for more than 35 years now. Although in the past already a large deal of research was performed into the subject of the behavior of cellular beams, almost no attention has been paid to the application of cellular members as columns. The column will be analyzed using the finite element method to calculate the critical load and compared with the Eurocode3 standard

ABSTRACT. With people's health status according to statistics getting worse and worse, improving the quality of health is an inevitable need that many researchers are interested in. In addition to improving through eating, improving the living environment in homes and workplaces is also essential. Nowadays, many countries around the world have implemented many house models that apply natural ventilation instead of artificial air conditioning system, because natural wind is better and also feels more comfortable. Therefore, the study of controlled natural wind-catching architecture is necessary and consistent. Research in this field can help improve the living environment for people. The objective of the paper is to simulate ventilation solutions based on experience in construction works by finite element method through ANSYS software to consider and evaluate the feasibility of these solutions. If the simulation results match or approximate the actual verified results, they can be applied to the improvement of natural ventilation structures to create a better indoor living environment, meeting the requirements of the environment. more comfortable diagnostics.

ABSTRACT. To meet the needs of coastal economic development, many reinforced concrete structures serving the traffic infrastructure system in saltwater areas have been built. However, the deterioration of the life of reinforced concrete works in the marine environment still occurs frequently. Research results show that more than 50% of reinforced concrete structural parts are corroded, severely damaged or destroyed after only 10 to 30 years of use. When the structure is subjected to the combined effects of moisture, temperature, and chemicals to corrode steel, glass fiber reinforced polymer (GFRP) bars are the superior solution to replace reinforcement. GFRP reinforced concrete has been widely used worldwide, however, in Vietnam, research and production is still limited. Therefore, the study of mechanical behavior of fiber reinforced concrete structures is really necessary. This paper will apply the finite element method to simulate the behavior of prestressed fiber reinforced concrete column structures. The effectiveness of fiber reinforced concrete will be compared to steel reinforcement when applied to this type of structure.

ABSTRACT. The electron inelastic mean free path (IMFP) is an important quantity for studying electron transport in condensed matter and for various types of electron spectroscopy/microscopy. For decades, experimental techniques and theoretical models have been developed to determine this quantity. However, the determination of low-energy IMFPs is still a challenge. Recently, we have presented a theoretical approach to overcome this problem. Accordingly, we determine the IMFPs for energies below 100 eV within the dielectric formalism and the time-dependent density functional theory. Our calculated IMFPs for elemental solids and monolayer graphene agree well with experimental data. In this talk, we present an overview of the recent progress in this field and report our latest results. We show that the presented approach is general and reliable not only for bulk materials but also for two-dimensional materials.

ABSTRACT. Graphene-based materials have attracted enormous interest, due to their fascinating optical and electronic properties. Here, the systematic investigations on the geometric, electronic, and optical properties of a graphene monolayer and its hydrogenated systems, will present the diverse quasiparticle behaviors, e.g., the critical factors due to the various atoms, orbitals, spin configurations, and chemisorption cases. Moreover, the significant mechanisms, the π/σ/sp2/ssp3 chemical bondings, as well as on-site electron-electron Coulomb interactions [the Hubbard-like spin-based ones], are completely identified from the relevant physical/chemical quantities. The main features of crystal symmetries, electronic energy spectra, wave functions, and optical excitations are directly linked together only under this unified viewpoint. Specifically, it is very interesting in developing the excitonic theories of layered materials, since such systems might possess unusual charge screening effects. The current study is of paramount importance, not only for basic sciences but also for high-tech applications, e.g., spintronic and hydrogen energy storage applications.

ABSTRACT. Recently, the investigation of high-order harmonic generation (HHG) emitted from polar molecules such as CO, NO, OCS has been paid much attention. In the difference from HHGs of atoms or symmetric molecules that contain only odd harmonics, the HHGs emitted from polar molecules possess both odd and even harmonics due to the symmetry breaking of the molecule itself. Therefore, the quantity characterized by the ratio of the intensities between the neighboring even and odd harmonics, called the even-to-odd ratio, is substantial in probing molecular dynamics or molecular ensemble. In general, most of the theories are based on the single-active electron approximation, in which only the outermost electron can be ionized and then recombined into the parent ion to emit HHG. Meanwhile, the core electrons are considered “frozen” associated with the nuclei. However, recent studies have proved the significant influence of the multielectron effect on the ionization rate, and as a consequence, the HHG intensity. But the impact of the core-electron on the even-to-odd ratio is still desirable. This report presents the influence of dynamic core-electron polarization (DCeP) of CO molecules on the even-to-odd ratio. The HHG is theoretically simulated by numerically solving the time-dependent Schrӧdinger equation. We indicate that the DCeP considerably affects the even-to-odd ratio. Notably, considering the DCeP effect makes the even-to-odd ratio is compared to the experimental data. We then clarify that this influence is attributed to the effect of DCeP not only on the intensity but also the phase difference of the adjacent attosecond harmonic bursts.

ABSTRACT. The adsorption of hydro on Pt(100) is investigated theoretically within the conventional ultrahigh vacuum (UHV) surface modeling. Both density functional theory (DFT) and Monte Carlo (MC) simulation are implemented to determine the stability, vibrational properties of adsorbed hydrogen atoms and the H – H pair interactions. From the converged data, it is found that the H adsorbed on the bridge (B) sites have the strongest binding energy, meanwhile, the H on the top (T) sites vibrate with the highest vertically stretching frequency. In the increment of H coverage (Θ_H), up to 1ML, only the H on B sites are accounted and the shape of g - value curve obtained in MC simulation shows a good agreement with the result of cyclic voltammetry measurement. Reducing the pair interaction parameter about 30%, the g – value is also decreased and from 0.3 to 0.6 respect to Θ_H, the g – value is well consistent with the experimental data. This indicates that the interaction of H – H on Pt(100) is mainly attributed to those H absorbed on B sites.

ABSTRACT. Water, one of the most abundant substances in our planet, still contemporarily remains mysterious. Aside of many trivial properties that we knew about water such as odourless liquid, transparency or boiled at 100 Celcius degree and frozen at 0 Celcius degree in normal condition; the water may manifest unexpected properties in specific conditions, especially the phase trasition. The structural phase of water has been shown to considerably differs from those in normal condition in term of confined volume around water molecules. In 2017, an experimental research team in MIT first time observed the unprecendented “frozen” water at temperature above boiling point by heating it using carbon nanotube. Although many previous research, especially computational, have proven the bizzare high-temperature-solidfication of water in confined space, but none of them even until recent moment exceeded boiling point. One reason given by the team in MIT was due to the diameter variation of carbon nanotube, with the shift from 1.05 nm to 1.06 nm could lead to substantial decline in water solidifying temperature. However, there is still one factor that should be take into account, that is the heating rate of water, which was not mentioned in many relevant research. Since temperature changing rate has been proven to affect the phase transition temperature of materials, it needs to be considered in such thermosensitive system like water in carbon nanotube. By using MD simulation method, this in-silico study aims to show the influence of heating rate to solidifying temperature of water in carbon nanotube, as well as attempts to reproduce the result of “frozen” water above boiling temperature. Additionally we will verify the phase structural differences of “frozen” water in term of heating rate. The results of this study may provide the better insight of water molecule behavior in confined space, as well as according to the the MIT research team, it may also give potential aid in creating proton-conductor at least ten times faster than any in-manufactured materials.

ABSTRACT. Abstract In this study, we use the classical molecular dynamics (MD) method with the Verlet algorithm and with the Stillinger - Weber potential to simulate phase transition of two-dimensional (2D) germanene. The influence of size on the formation of crystalline 2D germanene is investigated in details for models containing 8100, 6400, 4900, 3600, 1600, and 400 atoms. The changes in the thermodynamic and structural properties of the models are studied in order to clarify influence of size on the formation of models. We find that for models with the size larger than 6400 atoms the size effects are not pronounced. In contrast, the size effects are significant for the size smaller than 6400 atoms. The structural properties of crystalline 2D germanene are discussed through radial distribution function, coordination number, ring, interatomic-distance, and angle distribution. Our MD simulation provides helpful insights into the atomic mechanism of the formation and thermodynamics of this 2D material.

ABSTRACT. The ternary LiFeO2 compound presents unusual essential properties. The main features are thoroughly explored from the first-principles calculations. The concise pictures, the critical orbital hybridizations in Li-O and Fe-O bonds, are clearly examined through the optimal Moire-superlattice, the atom-dominated electronic energy spectrum, the spatial spin-/charge-densities, the spin-polarization projected density of states, and the strong optical responses. The unusual optical transitions cover the red-shift optical gap, various frequency-dependent absorption structures, and the most prominent plasmon mode in terms of the dielectric functions, energy loss functions, reflectance spectra, and absorption coefficients. Optical excitations, depending on the directions of electric polarization, are strongly affected by excitonic effects. The close combinations of electronic and optical properties can identify the significant spin and orbital hybridization for each available excitation channel. The developed theoretical framework will be very useful in fully comprehending the diverse phenomena and optoelectronic applications of other emerging materials.

ABSTRACT. Modeling glassy SiC nanoribbon by cooling rapidly the SiC liquid from 8000K to 300K is carried out by molecular dynamics (MD) simulations. Two separated MD simulations are performed, one of which uses the Tersoff potential and the other one uses the Vashishta potential. The temperature dependence of various structural and thermodynamic properties of the systems is analyzed and discussed via the radial distribution functions (RDFs), the coordination number distributions, and the ring statistics. We find that the Tersoff potential is clearly more appropriate in order to obtain the glassy SiC when rapidly cooling is employed.

ABSTRACT. The structural evolution of silicon carbide nanoribbon (SiCNR) by heating from 300 K to 8000 K is carried out by molecular dynamics (MD) simulations. Different size of model from 7000 to 20000 atoms are investigated to study the size dependence of SiCNR upon heating. The temperature dependence of various structural and the melting point of every single model are calculated and discussed via the total energy per atom and the heat capacity. The melting points of 7000-atom, 10000-atom, and 20000-atom models are 6600 K, 6800 K, and 7050 K, respectively. In this range of study, the melting point tends to shift to the higher teperature when the size of model increases.

ABSTRACT. Abstract Size effects on atomic structure and various behaviors of the amorphous two-dimensional SiC nanoribbons (a-2D SiC NRs) are studied by means of molecular dynamics (MD) simulations. In the present work, we take the Tersoff potentials for MD simulations of the a-2D SiC NRs. Our simulations suggest that the a-2D SiC NRs can be obtained by cooling from the melt via using appropriate interatomic potentials and cooling rate. Atomic structure of the a-2D SiC NRs is analyzed in details, especially, structure of the edge region. The changes in the thermodynamic and structural properties of the a-2D SiC NRs are studied in order to clarify influence of size on the formation of models. We find that the glass temperatures of models (containing 3328, 7168, and 14336 atoms) are different. On the other hand, the radial distribution functions (RDFs), coordination numbers, ring statistics, interatomic distances, and bond-angle distributions of three models are investigated and compared in details. Moreover, we propose that the a-2D SiC NRs would have many important applications in electronics and mechanical devices

ABSTRACT. Hyper-elastic materials are materials that are able to withstand great deformation and recover after exerting an applied force. Rubber, rubber-like materials and many other polymer materials are hyper-elastic materials. These materials have been and are increasingly used in engineering. Different from metallic materials, the deformation properties of hyper-elastic materials are much more complex than the deformation of metallic materials that we often come into contact with. The relationship between stress and strain of this material is highly nonlinear and often very different between tensile, compressive and shear strain. For these reasons, it is much more difficult to simulate this material than with metallic materials.

ABSTRACT. Electricity is generated in many different ways such as solar energy, wind energy, wave energy, or energy from natural fossil materials. Wave energy converter (WEC) is considered one promising renewable energy collection equipment. It is capable of exploiting the recurrence down of sea waves. In which the device is oscillating Water Column (OWC - Oscillating Water Column) is one of the most important devices developed in converters wave energy conversion. These types of OWC use the airflow generated by the work changes the pressure inside the chamber assembly as the oscillating water column flows out and flows in. In this paper, numerical simulation is using commercially available tools Fluent and CFX for fluid dynamics analysis in the air chamber and well turbine of this device. Based on the Numerical Wave Tank (NWT) model is simulated in a two dimensional used in this model, which is constructed mainly based on the spatially averaged Navier Stokes equation with the k-ε model for simulating the turbulence and modeled with Volume of Fluid (VOF). Axial-flow turbines system and future development as well as the proposed limitations will be discussed in detail.

ABSTRACT. Nowadays, Diesel engine is one of the most common types of engines in mechanical devices and vehicles for its contributing factors as regards high efficiency, cheaper genre of consumed fuel, its nonflammable fuel at ambient temperature, which brings cost-effectiveness and high safety for users. Among those researches, engine efficiency plays an essential role in the quality of any Diesel engine. As a result, intensive researches into this type of engine usually attract significant concern from mechanical experts, researchers and engineers to improve as well as innovate Diesel engines’ remaining disadvantages regarding efficiency, exhaust fume, noise and so forth, apart from the factor of efficiency. Such studies help the improvement of Diesel engines in terms of not only efficiency but also the environmentally-friendly of exhaust fume. Moreover, thanks to the advancement of distinctively special assisting tools, for example simulation softwares (like Abaqus, Ansys, Catia, Comsol, etc.), Diesel engine studies can be more time-effective and labor-saving than traditional experiment methods. The solvers of those simulation softwares are mainly based on theories of Finite Element Method (FEM) – a well-known and effective numerical method these days. The simulation of behaviors or responses of Diesel engine’s components grants manufacturers in general and engineers in particular an overview of their desire engine, by which they are able to estimate the engines’ outcomes or defects. On grounds that, they can make some proper modification and adjustment of the engine configuration to improve, or even innovate the quality of Diesel engine. In this study, a simulation of Diesel engine’s combustion phase shall be carried out in accordance with the Knock Integral Model (KIM) to predict the performance of the start of combustion which is the most significantly vital stage to the whole operating cycle of Diesel engine. The sole model for this study shall be referred to that in a published paper by the Society of Automotive Engineers (SAE). To be specific, the results relating to temperature and pressure done by the combustion phase of Diesel engine shall be inspected thoroughly.

ABSTRACT. This paper presents the research in an attempt to realize a mobile laminar airflow system for preventing the contamination of airborne pathogens by protecting the surgical site area as well as the instrument table as low-cost as possible. The proposed device was verified through the simulation. Computational Fluid Dynamics (CFD) was performed to optimize the system design by examining and evaluating the results, as well as computing the aerodynamic characteristics for the system's centrifugal blower and taking fan pressure variation into account while adjusting inlet flow. As a result, sterile conditions may be created instantaneously and anyplace using this proposed laminar airflow system. The innovative layered airflow sterilizer may achieve a local Biosafety Level II in a specific area, such as an isolation room, patient bedroom, or operating room. The numerical results show that the total pressure maintained inside the blower increase as the flow rate gets larger. The results of this study provide an essential basis for optimizing system design in future investigations.

ABSTRACT. In the on going efforts against COVID-19 pandemic, sterilization is one of the most effective and safe method. This subject study to design a disinfection chamber. The main component of the chamber is a 360-degree mist sprayer, combined with an infrared sensor installed inside the chamber that automatically activates the disinfection spraying process when a person steps in. The system is designed as a module so it can be easily installed, uninstalled, and transported. A complete installation system can disinfect up to 1,000 people per day. Disinfection chambers have an entry point, an exit point, an enclosed chamber where the disinfection takes place, power supply, solvent supply, chemical chamber/mixer, air supply and compressor (typically but not always), and a spray mechanism. Optional features include in-chamber power outlets, lighting features, audio/video options, temperature scanners and chemical atomizers. It is expected to be installed in areas at high risk of COVID-19 infections such as quarantine areas containing people infected with COVID-19, as well as at hospitals, supermarkets, railway and bus stations, airports, offices, schools, and other crowded areas.

ABSTRACT. Secondary metabolites in medicinal plants are important bioactive substances used to treat many diseases. Their biosynthesis and content are influenced by environmental factors, in which soils play an important role. In particular, metallic elements soils affect the growth and synthesis of active compounds in medicinal plants. In this study, we evaluated the effect of particle sizes and sampling depths on the semi-quantitative values of metals at Tinh Bien and Cam Mountain areas in An Giang province by X-Ray Fluorescence Spectroscopy (XRF). Simultaneously, the total phenolic and flavonoid content of six medicinal plants collected in An Giang were also examined, thereby preliminarily investigating the effects of the element's content on secondary metabolites in herbs.

ABSTRACT. Ultrasound, a complement to mammograms, has been considered as a promising modality in screening highly dense breast cancer, e.g. lack of calcification, due to its high sensitivity, safety, and inexpensive. In order to improve the screening rate, Computer-Aided Diagnosis (CAD) systems have been developed with the interpretation of breast ultrasound images (BUSI). Segmentation is an important stage of CAD systems to detect cancer tumors. It is a challenging task although different segmentation methods have been proposed over the last two decades. This study aims to utilize MultiResUnet, a state-of-the-art FCN model, to segment and evaluate its dice and detection rate on BUSI dataset. BUSI dataset includes 630 images of benign and malignant masses. Our results are superior compared to the UNET model - a current standard and reliable Deep Learning architecture for image segmentation.

ABSTRACT. Colposcopy is a simple and effective method to detect cervical-related diseases. Currently, the diagnosis of some cervical diseases through collagen orientation is a new and promising trend. In this study, the method of visualizing collagen orientation at the cervical surface on digital images with a resolution of 1920×1080 pixels will be presented. Cervical images were acquired from the clinic with a white light source combined with the cross-polarization method. After applying image pre-processing filters and mapping cervical collagen fibers, the Radon transform was used to describe the orientation of the collagen fiber structure. Research results show that there are three regions of collagen fibers orientation. Collagen fibers are circularly oriented and less dispersed in the mid-region, while there is higher dispersed distribution that can be found in the inner and outer regions of the cervix.

ABSTRACT. The lesions of cervix have become very popular, and cervical cancer is one of the most common cancers in women. Physical symptoms of cervical pathology are include of abnormal epithelium as well as atypycal blood vessels on the surface. Among the colposcopic signs that identify cervical abnormalities are atypical vessels paterns. In this study, a new algorithm is proposed to enhance the contrast ratio of blood, and segment blood vessels to the surrounding epithelial. Images of the cervix were captured under polarized light source help to reduce the glare from the surface, then, the combining images and Sauvola thresholding are used to detect the vascular pattern.

ABSTRACT. Light source is a crucial factor in modulating plant morphogenesis and metabolism in the field of micropropagation. The common light source used for in vitro propagation is fluorescent lamps (FLs). However, the power consumption of FL is relatively high and a range of wavelengths is wide (350 – 750 nm), which is unnecessary for the plant development. Light‐emitting diodes (LEDs) have recently emerged as an alternative for in vitro micropropagation. LED emitting at proper wavelengths with plant photoreceptors may provide more production, plant morphology and metabolism. However, there has been little discussion about using LED in vitro cultures of Panax vietnamensis Ha et Grushv., a Vietnamese ginseng, generally distributed in the Ngoc Linh mountain areas of Vietnam. This study examines the influence of various LED systems on hairy root growth of Panax vietnamensis. Panax vietnamensis hairy roots were exposed to 6 different LED systems consisting of the mixture of 460 nm and 640 nm LEDs and a FLs lamp. The hairy root morphogenesis changed in response to light exposure at 19°C relative to the control hairy roots stored in the dark for 4 weeks.

ABSTRACT. Epilepsy is a group of neurological disorders characterized by recurrent epileptic seizures. According to the World Health Organization, there are about 50 million people who have epilepsy. By visualizing the EEG recordings, experts can diagnose the type of seizure and the damaged area of the brain to initiate antiepileptic drug thereby reduce the risk of future seizure. However, this current method is time-consuming and inflexible especially in Viet Nam. Thanks to recent advances in technology especially in signal processing and Artificial Intelligence aspects have been bringing advantages in classifying seizure stage from others efficiently. With the dotors’ help in Hospital Nguyen Tri Phuong located in Ho Chi Minh City, Viet Nam, we received about fifteen quanlity seizure files with associated notaions. The Hilbert–Huang transform (HHT) plays a potential role in analyzing data from nonlinear and non-stationary like EEG signals and Support Vector Machine (SVM) is a well – known method for detection with high accuracy. In this paper, we combine above two methods to automatically detect seizure signals. Firstly, the EEG signals were filtered by band pass filter from 0,5 Hz to 45Hz, then creating time-frequency image-based HHT, the histogram of grayscale sub-images has been represented for an intuitive view and detailed information to classify the signals. Some statistical features like mean, variance, skewness and kurtosis of pixel intensity within the histogram are extracted because they are different for some certain stages in EEG signals like normal, pre-seizure and seizure. In final step, the SVM was applied to classify seizure EEG signals. The receiver operating characteristics (ROC) curve are used for evaluating the performance of the classifier. The test classification results of the model reached over 90%. It is more convenient to distinguish between different data of seizure and non-seizure without difficulties in eye – based scanning and huge consumption of time.

ABSTRACT. Sign language is an effective tool for mutual communication between deaf-mute disabled people. However, the number of people who are capable of using sign language proficiently is very few. It virtually creates a language - barrier between people with disabilities and regular people. To solve this problem, we propose a portable device model to classify Vietnamese sign language designed for disabled people. This system adopts the motion history image (MHI) algorithm as the feature extractor. A Convolutional Neural Network (CNN) model is employed to classify and translate sign language to text in real-time. The framework is developed based on a Raspberry Pi 4. Experimental results revealed that the proposed framework obtained an accuracy of 99,5% on the test dataset demonstrating the feasibility of the proposed system in assistant to the disabled.

ABSTRACT. The increasing trend of time and pressure of students in learning process with inadequate attention to health has made spinal abnormal symptoms more and more common in the world. In particular, spinal deformity is one of the causes affecting the normal development of adolescents, causing a number of circulatory and respiratory diseases and leading to psychological effects as well. Therefore, early detection of spinal deformities is very important in routine scoliosis screening at secondary school. The purpose of this study is to investigate the actual status of spinal deformity in students using DIERS formetric 4D device, as well as to find out some leading causes in order to propose recommendation to avoid them. Pilot experimental measurements were carried out on a group of 9 students composed of 4 male and 5 female. This is a new spine measurement method no using ionizing radiation, giving multiparameter results and suitable for routine scoliosis screening for all ages. The results showed that all 5/9 students have had abnormal signs such as lordosis, kyphosis, scoliosis. Three of 4 female students have showed large pelvic deviations. The above cases can be caused by the prolonged sitting time, the lack of physical exercise and wrong sitting posture. Abnormal cases in women have some common features of living habits. Mentioned results partly shows the risk factors consistent with common surveys that need the proper attention of government, education system and community about spine health monitoring.

ABSTRACT. The deposition of Aβ oligomers is proved to be a damage cause for AD patients in which the mechanism of Aβ16-22 fragments is believed to keep an important role in the fibrils’ aggregations due to its β-contents. The more β-contents formed the more Aβ-fibrillary conformations created. In a previous study, we have successfully constructed the Aβ16-22 hexamer configuration under the inhibition of the epigallocatechin-3-gallate (EGCG) compound. However, the environment controlled 6Aβ16-22 association change was neglected. So, in this scheme we are motivated to make an atomistic investigation via two molecular dynamic simulations (MD): Aβ16-22 hexamer and EGCG complex, one in normal condition pH = 7.0 and other in lower one pH = 5.5, respectively. The received data provides us an evidence to determine the decreasing of β-contents under the co-operative interaction of low pH and EGCG inhibitor. Finally, in agreement with the experimental investigation, our observation adds a physical insight into the picture of the computational aided drug design in Aβ treatment.

ABSTRACT. The current status of antibiotic resistance is global, with the emergence of strains of Methicillin-Resistant Staphylococcus aureus (MRSA) also known as super-resistant strains, with much faster rates of antibiotic resistance than the speed of introducing new antibiotics into clinical treatment, especially in developing countries. Through a study at Boston University (USA) published in 2019 found that 460nm wavelength can decompose the carotenoid pigment staphyloxanthin, the compound that makes the yellow properties of 'Staphylococcus aureus', this pigment acts as an antioxidant compound that prevents bacteria from being killed by oxidative of the immune system. Therefore, the elimination of this compound is of paramount importance in the destruction and treatment of infections caused by MRSA. Here, we focus on light source efficiency based on two basic factors: emission frequency and intensity, and investigate and evaluate the influence on STX compounds to optimize light source and create. There should be an opportunity for a new treatment

ABSTRACT. The Multi-slice CT Scanner simulation software is designed for an already existing CT Scanner simulation system. The software can control the simulation system to simulate the operation of a conventional CT Scanner with scan modes: Standard, Helical and Scanogram. The main idea of the software is to simulate visually the acquisition process of the projection data when the simulation system is performing hypothetical scan operations and to simulate visually the process of reconstruction image slices. The software is written in C sharp programming language and programmed on Windows Presentation Foundation (WPF) programming interface by Visual Studio. It is designed to run on Windows operating system. Refer to the operating procedure of the CT Scanner system in practice to build a suitable image reconstruction algorithm for the simulation system. Using MATLAB's built-in image reconstruction algorithm (ifanbeam), to generate Sinogram images from sliced images, then save the Data sets including the generated Sinogram images and the corresponding original image slices. To visualize the process of the reconstruction of images and the data acquisition, perform output each column of the Sinogram images matrix that had been created and stored in the Data sets, corresponding to each scan angle of the gantry’s angular position when the simulation system is performing a hypothetical scan operation. After displaying the entire Sinogram image of a sliced image, the reconstructed image of that sliced image then display for implementation. The process continues and repeats until the simulation system completes its operation.

ABSTRACT. The performance in endurance sports can be significantly influenced by the way how the concentration mind of athlete is focused. Many psycho-physiological models have drawn the same conclusion that the decline in performance may occur if the athlete shifts his focus so much to his movements, which adversely affects the subconscious aspect of the movements. Besides, for the promotion of active physical training to protect the public's health, stimulating interest in endurance exercises is a matter of concern to encourage sedentary individuals maintaining healthy exercise habits. In such context, this research was conducted on sedentary college students to examine their performance between focused and subconscious action in endurance cycling task with two following goals: (1) to analyze the difference in physical responses between two separated regimes: in the first regime, participants were required to monitor the breathing rhythm (subconscious action) and in the other regime, participants were instructed to control strictly the movement to reach the best performance (focused action); (2) to evaluate the level of impact of mentioned instructions to the perception or the excitement of the participants during exercise. There is shown that results of the subconscious action were significantly better than those of the focused action, that proves the adequacy to aforementioned theories with respect to both psycho-physiological factors, not only for professional athletes but for other normal people. That is the premise to develop appropriate support methods for the issue of physical training to protect public health.

ABSTRACT. The study on gas sensors is becoming a prominent issue for serving people’s life especially in controlling air quality and detecting harmful gases for human health. There are many principles to develop a gas sensor. One of those is bases on the change of resistance on the surface of the sensing material. An instrument used for measuring resistance is crucial for gas sensing systems to develop these sensors. For this reason, a designed circuit to measure resistors in width range measurement is required. This device bases on the principle of Ohm’s law, where the current passing through the electrode surface is converted into voltage and collected by analog to digital converters (ADC). In addition, this device uses Bluetooth embedded on Microcontroller Unit (MCU) ESP-32 to communicate wirelessly with another device such as a computer or smartphone to help researchers avoid the gases directly during the research time, especially with the toxic gases. To this end, the product of this topic can measure the resistor in a range from some dozens Ohm to several MOhm with 16-bit ADC resolution. It also includes a user interface written by trial license MATLAB for observing to adjusting the experiments easier.

ABSTRACT. Recent researches have shown that there is a visual abnormality of children with Autism Spectrum Dianogstic (ASD) compared with typical development (TD), ASDs spend less more time observing the face and eyes, tend to look at the unrelated object. The Eye Tracking model is used to diagnose early autism in children recently. The stimuli used are often related to videos or photos of human faces. In this article, we have built a gaze data classification model of ASD and TD children through images based on atypical visual attention of autistic children. We used gaze data from [1], 14 children with ASD, and controls. From the gaze data, we create AOI (Area of ​​Interest) features associated with fixation points. Finally, data were declared by the SVM algorithm (Support Vector Machine) to distinguish between the ASD and the control group. The total classification result obtained is 70.83%, which shows differences in observations of visual topics ASD and TD: animals, buildings, people,…. ASDs are more susceptible to distraction and tend to look at objects rather than people.

ABSTRACT. In this paper, we present some results obtained from the simulation of low power 633, 780, 850, and 940 nm laser in the liver by Monte Carlo method, with the model of the liver, consisted of 5mm derm, 7mm subcutaneous fat, 5 mm muscle layer. Based on these results, we fabricated devices called “Laser Semiconductor Optoacupuncture and phototherapy Device” using 780 and 940nm semiconductor lasers to treat chronic hepatitis. We combined with the doctor in An Giang province to clinical practice for 50 voluntary patients with chronic hepatitis. We used a 650 nm wavelength intravascular semiconductor laser treatment clinically to provide high-quality blood to the patients’ liver. Treating of the phototherapy of the skin with two semiconductor laser beams with 780 nm and 940 nm wavelengths directly affect the liver from the surface of the abdomen. At the moment, we use the treatment on acupoint with 940nm- wavelength laser. A treatment course consists of 20 times for the patients is treated continuously. The patients tested with the ALT and AST before and after treatment with after 3 courses. We use the SPSS 23 statistical method to evaluate outcomes of treatment. The clinical symptoms of the patients such as fatigue, nausea, indigestion, fever, jaundice, yellow eyes almost completely have gone out after treatment. Low-level laser therapy offers a good response in patients with moderate to severe hepatic impairment such as the AST of 56.380 ± 10.162 and 39.260 ± 4.869; The ALT of 56.540 ± 13.580 and 41,360 ± 7,488 for before- and after treatments, respectively. Low-level laser therapy for patients initially has good results, high therapeutic effectiveness, no catastrophic or side Effects, and the statistical significance is of p < 0.001. This research applied the ethical principles of Helsinki Declaration in human researches. The research was carried out using non-invasive methods on humans with the regulations of the University of Technology, Vietnam National University Ho Chi Minh City and the relevant regulations.

ABSTRACT. Alzheimer’s disease (AD) is a neurodegenerative disorder and one of the main causes of dementia. The disease is associated with amyloid beta (Aβ) peptide aggregation forming initial clusters, then fibril structure and plaques. Other neurodegenerative diseases such as type 2 diabetes, amyotrophic lateral sclerosis, and Parkinson’s disease follow a similar mechanism. Therefore, inhibition of Aβ aggregation is considered an effective way to prevent AD. Recent experiments have provided evidence that oligomers are more toxic agents than mature fibrils, prompting researchers to investigate various factors that may influence their properties. One of these factors is nanomechanical stability, which plays an important role in the self-assembly of Aβ and possibly other proteins. This stability is also likely to be related to cell toxicity. In this work, we compare the mechanical stability of Aβ-tetramers and fibrillar structures using a structure-based coarse-grained (CG) approach and all-atom molecular dynamic simulation. Our results support the evidence for an increase in mechanical stability during the Aβ fibrillization process, which is consistent with in vitro AFM characterization of Aβ42 oligomers. Namely, using a coarse-grained model, we showed that the Young modulus of tetramers is lower than that of fibrils, and, as follows from the experiment, is about 1 GPa. Hydrogen bonds are the dominant contribution to the detachment of one chain from the Aβ fibril fragment. They tend to be more organized along the pulling direction, whereas in the Aβ tetramers no preference is observed.

ABSTRACT. In this talk, we present an overview of the perturbative computation in high energy physics. In particular, based on the method developed in [K.~H.~Phan and T.~Riemann, Phys.\ Lett.\ B {\bf 791} (2019) 257], detailed analytic results for scalar one-loop two-, three-, four-point integrals in general d-dimension are presented in this paper. The calculations are considered all external kinematic configurations and internal mass assignments. Analytic formulas are expressed in terms of generalized hypergeometric series such as Gauss 2F1, Appell F1 and Lauricella FS functions. We then apply the above results to the phenomenological analysis of the Higgs physics at the Large Hadron Colliders. For example, one-loop formulas for Higgs decay to 2 photons, Z + photon and fermion pair with a photon are discussed.

ABSTRACT. Cancers release certain gases in the patient’s breath. Therefore, early-stage and non-invasive diagnosis via gas sensors has attracted much attention from researchers. ZnO is a potential sensing material due to its high sensitivity and high selectivity toward both oxidative and reductive gases; however, there is no study available to clarify the electronic and thermoelectric properties of ZnO for lung cancer-related gas detection. In this report, we elucidated the current topic by the density functional theory calculations.

ABSTRACT. The designs of target-drug delivery systems are attractively concerned due to their efficacy and safety. Fullerene is the first symmetrical carbon nanomaterial invented in the world. Due to the special properties of fullerene, it is being an emergent topic in the field of nanomaterials in recent years. This research focuses on the computational approach of in-bound fullereo-curcuminoid derivative systems for drug delivery, with adequate fullerene size to encapsulate curcumin molecules. This proposed model is promising not only to create a better anti-solvent shield for the curcumin molecule throughout the delivery path to the target cells but also to manipulate the curcumin dose since the fullerene shield may increase the efficiency of curcumin carrying. The approach of this research is to use the computational simulation method to investigate the epidermal growth factor (EGF) receptor binding and the physicochemical parameters of the curcumin molecule encapsulated in fullerene. The density functional theory (DFT) calculation is conducted to observe the electrical and energetic properties of the curcumin-fullerene encapsulation system. The obtained system is then docked with the target receptor. After that, the size-modified defected gap will be created on the fullerene surface in the release process of the curcumin out of the fullerene, to interact with the target residues on the receptor will be observed by using MD simulation as well as their interaction stabilization.

ABSTRACT. A monolayer structure of silicon carbide (SiC) had been studied as a hydrogen storage material using first principle calculations. The two dimension SiC model consists of 98 Si and C atoms, cut out from previous MD simulations, was tested for optimal geometry and k-point density by the SIESTA program. The ground state total energy obtained from the SIESTA’s results were then used in the adsorption energy calculations with consideration of zero-point energy using harmonic approximation. The only favorable binding sites for hydrogen adsorption have been found are the top sites (H is directly on top of Si and C atoms). The hydrogen adsorption energy is highest in topSi position (about -0,709 eV). The results also reveal that the chair conformer is the most stable adsorption configuration, reaching the hydrogen gravimetric capacity of 4.7 wt%.

ABSTRACT. The issue of hydrogen (H) electro-adsorption on different Pt surfaces is revisited to settle its theoretical description within the conventional ultrahigh vacuum (UHV) surface modeling and the semilocal Kohn–Sham level of the density functional theory (DFT). By performing a converged DFT calculation, we have confirmed nearly degenerated nature of H on the different sites when the nuclei are treated classically. When the zero-point energy correction is applied, the H on the fcc hollow site is significantly more stable for Pt(111), while the H on the short bridge site on the ridge is found to be the strongest binding sites at the low coverage region, and at the higher H coverage region, up to 1 ML, the on-top sites of the micro-facet (F) get populated for the missing row Pt
(110)-(1x2). Relative abundance of the H adsorption sites was investigated by performing a Monte Carlo simulation using a lattice gas model parameterized by the DFT calculation. By comparing the calculated results with recent cyclic voltammetry data, we found good agreement between theory and experiment but minor discrepancy exists in that the H–H interaction is underestimated by ~10%. Possible origin of the discrepancy is the hydration effect neglected in our model although we cannot exclude the possibility that error of the semilocal approximation within DFT will also play a role.

ABSTRACT. Red-River System (RRS) is the second largest basin in Vietnam. The basin is also characterized with high hydropower potential due to generally steep topography and high rainfall in the mountain area. During recent years, the hydro-power reservoir system has been developed, nearly completed as planned and making up 24% of 48,573 MW total national electricity generation. The development of hydropower reservoir system has certain contribution to social economic status of the basin, however, since 1998, there have been about 8 drought events with increasing intensity in the basin. The impacts of drought would be minimal if the water conflicts do not exist between power generation and water supply reu=quirement. The conflicts often occur during peak demand of the two biggest water user groups, agriculture from January to March and hydropower from April to June.

Operation optimization algorithm following the Non-dominated Sorting Genetic Algorithm II (NSGA II) with 2 objective functions of total hydropower cost and water level at Ha Noi has been carried out. The optimum parameter sets for reservoir operation policy were found using the parameterization simulation optimization (PSO) approach on the model of reservoir system and the Artificial Neuron Network (ANN) emulator representing the river system reponses to the discharge combination scenarios.

The model has been validated for the year 2011. Optimized operation policy for dry season of 2015–2016 shows 2.67 ÷ 6.33% increase in total relative hydropower cost and 1.18 ÷ 2.77% increase in average water level at Hanoi. The model applied for reservoir system on RRS of Vietnam offers better option for water resources operators to reduce the water related conflict while increase the benefit of water resources of the basin.

ABSTRACT. Water quality models are increasingly being used worldwide to assess water quality under different socio-economic development scenarios. Since 1925 when Streeter-Phelps published fundamental work on water quality modeling [1], the development of "Forward problem" research has made a breakthrough and this area is conceptualized in [2]. Although the interest in the inverse problem is concerned, scientific publications in this area of research are still quite limited. It is worth mentioning that research [3][4][5] has done some research on the inverse problem. In which research [3] has found an analytical solution for the inverse problem based on the steady-state of Streeter - Phelps equation. However, extending this result to the unsteady state requires additional studies. One of the efforts made in [4] in which, based on the numerical solving scheme according to the Crank - Nicolson scheme (CNS), created an algorithm to solve the forward problem and as a basis for the application of the least-squares algorithm to determine the reaeration and dispersion Coefficients which has taken a lot of published articles over the years. In addition, difficulties arise when an automatic measurement system is required to determine the sets of parameters Biological Oxygen Demand (L) and oxygen deficiency (D) for the inverse problem. To solve this task, the Mike package is used to generate datasets (L,D) for a certain period of time. In this report, the authors have built a set of tools to simultaneously solve both forward and reverse problems.

ABSTRACT. The ammonia synthesis system is an important chemical process used in the manufacture of fertilizers, chemicals, explosives, fibers, plastics, refrigeration. In the literature, many works approaching the modeling, simulation, and optimization of an auto-thermal ammonia synthesis reactor can be found. However, they just focus on the optimization of the reactor length while keeping the other parameters constant. In this study, the other parameters are also considered in the optimization problem such as the temperature of feed gas enters the catalyst zone. The optimal problem requires the maximization of a multivariable objective function which is subjected to a number of equality constraints involving the solution of coupled differential equations and also inequality constraints. The solution of an optimization problem can be found through, among others, deterministic or stochastic approaches. The stochastic methods, such as evolutionary algorithm (EA), which is based on natural phenomenon, can overcome the drawbacks such as the requirement of the derivatives of the objective function and/or constraints or is not efficient in non-differentiable or discontinuous problems. Genetic algorithm (GA) which is a class of EA, is exceptionally simple, robust at numerical optimization, and is more likely to find a true global optimum. In this study, the genetic algorithm is employed to find the optimum profit of the process. The inequality constraints were treated using the penalty method. The coupled differential equations system was solved using Runge-Kutta 4th order method. The results showed that the presented numerical method could be applied to model the ammonia synthesis reactor. The optimum economic profit obtained from this study are also compared to the results from the literature. It suggests that the process should be operated at a higher temperature of feed gas in the catalyst zone and the reactor length is slightly longer

ABSTRACT. High-order numerical schemes for shallow water equations with variable topography are constructed, based on exact Riemann solvers. The schemes are shown to be well-balanced and can provide us with a good accuracy. Although the schemes are of essentially nonoscillatory (ENO) type, visible oscillations can be observed for these schemes with large orders. Precisely, tests show that a 3rd-order ENO-type scheme provides us with convergence, but large oscillations appear in 5fth-order and 7th-order ENO-type schemes.

ABSTRACT. We establish the existence of diffusive-dispersive traveling waves associated with phase transitions in fluid dynamics equations. The fluid is assumed to be isentropic and of van der Waals type. The pressure, as a function of the specific volume, has alternative decreasing and increasing intervals and admits two inflections. So, besides the classical shock wave, a nonclassical shock wave can be observed. Using Lyapunov stability techniques, we can show that there exist traveling waves corresponding to each given type of shock wave in the case of a phase transition of a fluid.

ABSTRACT. Upon the recent development of the quasi-reversibility method for terminal value parabolic problems which are ill-posed in the sense of Hadamard, it is motivating to study the convergence of the numerical solution for the regularized problems. In this paper we use a finite element scheme based on the Newton method to approximate the solution of the regularized problem of a nonlocal coupled system of parabolic problem. We consider the well-posedness of the problem, give some error estimates and conclusions of the convergence rates.

ABSTRACT. We investigate the existence of infinitely many solutions for a generalized $p(\cdot)$-Laplace equation involving Leray-Lion operators. Under a local $p(\cdot)$-sublinear/superlinear condition for nonlinear term, we obtain the existence of a sequence of solutions approaching to zero/ infinity. Our approaches basically rely on critical point theories in Calculus of Variations. This talk is based on a joint work supervised by Ky Ho(University of Economics Ho Chi Minh City).

ABSTRACT. This work is devoted to a study the stability of a nonlinear SPDE. We can verify the existence and uniqueness of the solution of the equations. The exponential stability and the almost sure stability of the solution was considered and the required condition is simpler than those in some latest results. We also examine some numerical result to confirm the obtained result.

ABSTRACT. In this talk, we present some explicit criteria for the exponential stability of general functional differential systems. The stability conditions obtained are quite simple, easy to use and include many existing results as particular cases. Two examples are given to show the effectiveness and advantages of the obtained results.

ABSTRACT. In this report, we present some recent results on exponential stability of solutions to linear and nonlinear delay difference systems with continuous-time. A discussion and some examples are provided to illustrate the obtained results.

ABSTRACT. In this talk, we will study the problem of classifying of finite-dimensional real solvable Lie algebras whose derived algebras are of codimension 1 or 2. Namely, we introduce an effective method to classify $(n+1)$-dimensional real solvable Lie algebras such that the derived algebra of each of them is a given $n$-dimensional nilpotent Lie algebra. We also prove that the problem of classifying real solvable Lie algebras having 2-codimensional derived algebras is ``wild'' (hopeless). In addition, we introduce a subclass of the considered Lie algebras for which the wild property is broken and we give the complete classification of the presented subclass.

ABSTRACT. A purely algebraic algorithm is presented for computation of invariants (generalized Casimir operators) of Lie algebras. It uses the Cartan’s method of moving frames and the knowledge of the group of inner automorphisms of each Lie algebra. The algorithm is applied, in particular, to computation of invariants of real solvable Lie algebras having 2-dimensional derived ideals.

ABSTRACT. The research interest in finiteness separability of semigroups is inspired by Professor M.M. Leshokhin's work and by the work of four authors: Craig Miller, Gerard O'Reilly, Martyn Quick and Nik Ruskus "On separability finiteness conditions in semigroups", Journal of the Australian Mathematical Society, Published online by Cambridge University Press, 09 September 2021. Our research is to further investigate the P separability in semigroups with respect to various predicates P in general. Given a certain class S of semigroups. We study a problem of finding a class K of semigroups (not only finite) such that the class S is P- separable by mapping (such as homomorphisms, characters, generalized characters,...) from S into K. The problem of minimization of P- separability is also considered.

ABSTRACT. In this paper we consider two matrix equations that involve the weighted geometric mean. We use the fixed point theorem in the cone of positive definite matrices to prove the existence of a unique positive definite solution. In addition, we study the multi-step stationary iterative method for those equations and prove the corresponding convergence. A fidelity measure for quantum states based on the matrix geometric mean is introduced as an application of matrix equation.

ABSTRACT. Information fusion is a broad area that studies methods to combine data or information supplied by multiple sources. Aggregation is one of such process which is used in data analysis to obtain a single value from a set of values. For this purpose, the fuzzy integrals like Choquet integral, Sugeno integral can be used as aggregation operators. In decision theory we have to obtain aggregation of the preference values or satisfaction degrees. Common aggregation operators like arithmetic mean, weighted mean, median, mode etc. have some drawbacks because they only express the quantitative approach. But to express the qualitative approach like relation between criteria, decision making, fuzzy integrals such as the Choquet integral and Sugeno integral are considered. Thus, we deal with a much broader class of aggregation functions. These are based on the fuzzy measures which are non-additive and have been introduced by Sugeno in 1974. These non-additive measures and integrals generalize the traditional probability theory. Admission is the first important mission in education process of universities and colleges and has a great impact on the quality of teaching and learning. Well-constructed admission lead to recruit students with knowledge, skills, and attitudes that are suitable to the vision and core value of the education units, and orientate the learning process of students. To conceive, design and implement mixed criteria are the best-practice solution for admission improvement purpose. For that reason, aggregated information from different criteria into one which apply fuzzy integrals and conduct with a real data set from Viet Nam Nation University, Ho Chi Minh City (VNU-HCM) are the main goal for this paper. This paper result would lead to new approaches in undergraduate admission policy for VNU-HCM in the near future.

ABSTRACT. The equilibrium problem and its generalizations had a great influence in the development of some branches of pure and applied sciences. The equilibrium problems theory provides a natural and novel approach for some problems arising in nonlinear analysis, physics and engineering, image reconstruction, economics, finance, game theory and optimization. In recent times, there were many methods in order to solve the equilibrium problem and its generalizations. Some authors proposed many iterative methods and studied the convergence of such iterative methods for equilibrium problems and nonexpansive mappings in the setting of Hilbert spaces and Banach spaces. Note that a generalized mixed equilibrium problem is a generalization of an equilibrium problem and a Bregman totally quasi-asymptotically nonexpansive mapping is a generalization of a nonexpansive mapping in reflexive Banach spaces. The purpose of this paper is to combine the parallel method with the Bregman distance and the Bregman projection in order to introduce a new parallel hybrid iterative process which is to find common solutions of a finite family of Bregman totally quasi-asymptotically nonexpansive mappings and a system of generalized mixed equilibrium problems. After that, we prove that the proposed iteration strongly converges to the Bregman projection of initial element on the intersection of common fixed point set of a finite family of Bregman totally quasi-asymptotically nonexpansive mappings and the solution set of a system of generalized mixed equilibrium problems in reflexive Banach spaces. As application, we obatin some strong convergence results for a Bregman totally quasi-asymptotically nonexpansive mapping and a generalized mixed equilibrium problem in reflexive Banach spaces. These results are extensions and improvements to the main results in [7, 8]. In addition, a numerical example is provided to illustrate for the obtained result.

ABSTRACT. Let A: D(A)⊂ X → Y be a linear, closed, densely defined unbounded operator, where X and Y are Hilbert spaces. Assume that A is not boundedly invertible. If equation (1) Au=f is solvable, and ‖f_δ-f‖≤δ then the following results are provided. Problem F_δ (u) □(∶=) ‖Au-f‖^2+α‖u‖^2 has a unique global minimizer u_(α,δ) for any f_δ,u_(α,δ)=A^* (AA^*+αI)^(-1) f_δ. There is a function α(δ),lim┬(δ→0)⁡〖α(δ)=0〗 such that lim┬(δ→0)⁡〖‖u_(α(δ),δ)-y‖=0〗, where y is the unique minimal-norm solution to (1). In this paper we introduce the regularization method solving Eq. (1) with unbounded operators. At the same time give an application to the weak derivative operator equation.

ABSTRACT. We study the properties of Carleson measures for bounded domains in C^n. Carleson measures play an important role in the study of holomorphic functions. In literature, Carleson measures have been considered for some restricted classes of domains, such as the unit disk, the unit ball or strongly pseudoconvex domains. The aim of this paper is to extend previous results to a more general class of domains. We observe some interesting properties of vanishing Carleson measures for domains with irregular boundaries.

ABSTRACT. Let $\Omega \subset \mathbb{C}^n$ be a bounded, strongly Levi-pseudoconvex domain with minimally smooth boundary. An Integral formulae are used to prove the $L^p$ continuity of Bergman projection. It gives us a tool to study the $\bar\partial$- Neumann problem on domains of finete type.