ABSTRACT. Greetings

ABSTRACT. Opening Speech

ABSTRACT. Effect of quantum fluctuations on the critical supercurrent through a mesoscopic normal-metal island

ABSTRACT. Effects of Zn and Ni substitution on the superconducting properties of the Nd1113 superconductor

ABSTRACT. Timeseries Anomaly Detection

ABSTRACT. The increasing trend of time and pressure in studying and working together with inadequate attention to health has made spinal diseases significantly increase. The practice of spinal screening has gradually become popular in many countries and by different methods. In which, assessment of Cobb angle on X-ray images is considered the gold standard in scoliosis screening. However, manual evaluation can lead to many unexpected errors and take a lot of time. The paper proposed the use of linear models in machine learning to predict Cobb angle from a dataset of 609 X-ray images (481 training and 128 testing). The results show that the random forest model is best suited to the dataset. The model will help predict the vertebral landmarks along with the Cobb angle values more accurately and save time. Although the model still has many limitations compared to studies using the same data set, it will be a premise for the development of spinal screening programs using artificial intelligence tools.

ABSTRACT. Sign language is a visual means of communicating through hand signals, gestures, facial expressions, and body language. It's one of the major forms for the Deaf to communicate with the community. In this study, we introduce a glove-based gesture recognition system to decode sign language from disabled people. The glove consists of an accelerator and five strain sensors that allow it to capture the user’s gestures. To decode the gesture to a corresponding command, a Convolutional Neural Network (CNN) model is employed. Captured data from sensors are used to train this model. The well-trained model is then deployed in real-time to recognize gestures from users. Moreover, other machine learning algorithms including KNN, SVM, Decision Tree, Random Forest, and XGBoost are also tested. Experimental results show that high accuracy of 99.8% of the test set is achieved indicating the feasibility of the proposed device in real-time recognition of Vietnamese sign language.

ABSTRACT. Early detection of stress can prevent people from suffering mental health problems. Related works showed that there is a connection between emotional states and the heart rate as well as Electrodermal activities (EDA). In this study, we employed PPG and EDA signals to recognize the emotions of the user during watching emotional pictures (e.g., IAPS). A wearable device was designed and fabricated for PPG and EDA measurement simultaneously. An experimental paradigm was designed and the experiment was conducted for eight subjects. Collected data were analyzed and features of both PPG and EDA signals were extracted to train several machine learning models. Results showed that a high average accuracy of 94.6% was obtained across 8 subjects showing that the combination between PPG and EDA is effectively used for stress recognition.

ABSTRACT. For people with motor voluntary loss, especially those with heavily disable such as paralysis or amputation, brain-computer interface ( BCI ) communication based on motor imagery (MI) offers many opportunities to help them regain their mobility and ability for function daily. This model classifies two class motor imagery using independent component analysis (ICA) and support vector machine (SVM), based on the mu wave power difference between the two types of left and right motor imaginings. Then, we compared the SVM method combined ICA with similar studies on the BCI competition IV data set 2b. The evaluation results demonstrate that classification model using ICA and SVM based on mu power’s variability is a good method for classifying motor imagery EEG signals with high classification accuracy

ABSTRACT. Previous researches have been made to present methods of automatically singel-channel EEG sleep stage scoring but the accuracy of N1 classification is relatively low compared to others stages’s. This research focused on classifying NREM N1 sleep stage in sleep transition based on frequency domain features, which are power spectral ratios between bands of brain waves, by using the binary Support Vector Machine (SVM) algorithm for Sleep EDF Expanded database. The model’s performances indicate that using SVM algorithm for spectral ratios related to theta and beta waves on PzOz channel is suitable for classifying Wake and N1 sleep stages with high accuracy and F1 scores.

ABSTRACT. Automated inspection system now a day is a must in mass production line. In order to optimize abilities of inspection system using computer vision (CS) technology in term of accuracy and speed the input data should be as good as possible. Good input data for computer vision system can be considered as clear images with high contrast, high resolution and high system resolution (um/pixel) with all the defect that have to be detected were highlighted out in comparison with non-defect area in sample. All above requirement can be archived just in case considering to the optical system (OPS) of CS system. Design of an optical system will be based on samples as per: material, dimension, defect descriptions and requested system speed. There's many types of inspected samples and defects will lead the OPS's design be impossible or can not be optimized to fit with requested requirement. One of them is the thin and transparent surface with tiny defects as: crack, dent, chip off... with the dimension of couple of 100 um. In this paper, we introduce an OPS designed for surface of storage disk inspection before coating stage in production line.

ABSTRACT. Recently, in dentistry the infrared technique has been developed strongly to detect dental lesions, based on the fact that the optical properties of damaged tissue under infrared light are significantly different from those of sound dental tissue. A number of research groups have paid attention to the application of machine learning strategies for classifying and analyzing infrared image data. The aim of the present study was to introduce the application of infrared technique and machine learning in detecting dental lesions. A number of tooth samples with different types of lesion was captured by our designed optical systems under infrared light 850 nm. Two deep learning models (Unet and Mask R-CNN) were used for training and identifying the presence of lesions in infrared images. The results suggest the effectiveness of Unet and Mask R-CNN models in diagnosing dental lesions via infrared images.

ABSTRACT. According to recent reports, there is an alarming reality in Vietnam today that about 90% of people have dental problems, mainly tooth decay. Dental diseases cause discomfort for patients and a loss of confidence in communication. Therefore, the demand for dental exams and treatments is increasing day by day. X-rays have long been used to treat dental diseases and are playing an increasingly important role in dentistry. The creation of cone-beam computer tomography (CTCB) has brought many benefits to users. This thesis mainly presents how to calculate the DAP number (Dose Area Product) at CTCB Orthophos SL and convert the unit of DAP (Gy.cm2) to the unit of the effective dose (mSv). The results obtained from nearly 100 CTCB scans show that the effective dose of the instrument Orthophos SL is about 0.2 mSv, which is satisfactory for the requirements for radiation safety even with the largest FOV. The study was carried out under the supervision of Denstply Sirona for the purpose of warning before taking, helping doctors (technicians) to manage the problems related to the imaging process and to minimize the radiation dose radiation on the patient, and determine the radiation on the patient in practice at the same time.

ABSTRACT. The gravitational flows of granular materials are omnipresent in nature such as landslide disasters, debris flows, snow avalanches, rock avalanches, and industrial processes such as the handling and transportation of material and foods. In natural events, such gravitational flows strongly depend on the inclination angle of the slope failure and the volume of the sliding blocks, but their mobilities and rheological properties still remain elusive. In this talk, the mobility and rheological properties of such flows as rock avalanches are presented by using the discrete element method for modeling the granular materials, collapsed on an inclined plane due to their self-weight before getting a rest at the deposition stage on a rough horizontal surface. These properties are characterized by the evolution of the ratio of the kinetic energy and potential energy during the flows, the morphology of the granular flows, and their runout distance. The results show that this kinetic energy first increases rapidly from the static state until reaching a peak. The rate of reaching this peak grows when the inclination angle is increased and the sliding volume is decreased. Beyond the peak, the kinetic energy rapidly decreases before depositing at a rest. Remarkably, the maximum value of the kinetic energy can be expressed as an approximately linear function of the inclination angle for each value of the sliding volume. These observations partly provide evidence for understanding the mobility of granular flows, tending to application in studying rock avalanches.

ABSTRACT. Aggregates or cemented granular aggregates of heavy (rigid) and light (soft) grains are commonly found in engineering; however, the mechanical strength of such aggregates and the contribution of these heavy and light grains to the aggregates’ strength still remain elusive due to lacking and limitations of experimental investigations. In this talk, we numerically investigate the effects of lightweight particle content on the mechanical strength of the cylindrical aggregates by using extensive three-dimensional discrete element simulations. The numerical method is constructed based on the linear spring-dashpot model with the inclusion of the capillary attraction law. The aggregates are randomly composed of two different groups of primary particles: light (with low stiffness) and heavy (with high stiffness), subjected to the axial compression test by applying a constant downward velocity on the top platen. We also study the stress contribution of the heavy-heavy, light-heavy, and light-light interactions on the mechanical behavior of such aggregates. We found that the lightweight particle content significantly affects the mechanical strength of aggregates and the stress contribution obtained by different interaction types above, in which the stress obtained by heavy-heavy interactions strongly dominates the mechanical strength of agglomerates. Meanwhile, however, the stress obtained by these contacts gradually decreases with increasing the lightweight particle content by up to 20%, leading to a decrease in the mechanical strength of aggregates, the stress obtained by light-light and light-heavy contacts increases gradually. For higher lightweight particle contents, the results continuously show the same tendencies but with lower rates. These findings robustly provide physical insights inherent in the contribution of the rigid and soft grains to the mechanical strength of cemented aggregates, leading to effective applications in engineering

ABSTRACT. Focusing on brain function studies by biosignal is essential in a field of study. Especially in the human state, detecting mental state via electroencephalography (EEG) helps to improve commercial quality products. The research goal is to test the efficiency level of the experimental protocol to estimate the concentration state. Therefore in this study, we produce a new experimental setup to evaluate the concentration. This experiment suggests EEG electrode placements, a period in each stimulation, and new stimuli by applying “motion-induced blindness” research to enhance concentration effectiveness. The testing approach uses a support vector machine (SVM) to distinguish between concentration and rest. This research result can use as a reference for the evaluate another stimulation method

ABSTRACT. Nowadays, lung diseases are increasing due to many different reasons, usually concerning pleural effusion syndrome. Low-level laser therapy has made significant progress in the biomedical field regarding diagnostic and therapeutic capabilities. For applying low-level laser in treatment, it is necessary to understand the absorption, propagation, and positive effects of the laser on each biological tissue and optimize the identification of biological stimuli in tissues. Therefore, many researchers have used the Monte Carlo method to simulate the propagation of low-level lasers through multiple layers of tissue. This paper uses the Monte Carlo method to simulate the propagation of low-level laser light at wavelengths (633 nm, 780 nm, 850 nm, 940 nm) from the human back skin surface through the skin tissues to the lung. As a result, each treatment's appropriate wavelengths, dose, and energy can be selected.

ABSTRACT. The Monte Carlo technique is versatile for simulating tissue light transmission. The simulation is based on the random steps the photons make as they move through the tissue. The steps are selected by statistical sampling of the probability distributions for the step size and angular deviation on each scattering event. After propagating many photons, the distribution of all photon paths gives an exact approximation to reality. Monte Carlo simulations have been considered the gold standard for estimating the results of other computational methods. This study uses the Matlab computational tool to build a 3-D Monte Carlo simulation program of light transport in biological tissues. The implementation of the algorithm is based on the MCML and mcxyz.c programs. In addition, building simulation algorithms on Matlab simplify operations for users and provides a basic model for educational purposes. An example simulation of the apple model examines light's propagation through normal and bruised apple tissue. The simulation yields matrices of energy deposition W (W / cm^3 / W. delivered) and fluence rate φ (W / cm^2 / W. delivered) of transmitted light in the tissue while recording the diffuse/transmitted reflectance spectrum as the light exits the tissue surface. The above results were produced by irradiating a Laser Gaussian beam of 650 nm.

ABSTRACT. Optical imaging using visible and near-infrared wavelengths(450-700 nm) used in quality assessment in foods such as meat or fruit is considered an alternative non-destructive analysis method to control food quality during the preservation process. In visible and near-infrared wavelength ranges, light can deeply penetrate foods and is used to detect and take biochemical measures. This research aims to study the configuration of reflectance images to choose the appropriate wavelength and optimize the distance between the light source and the detector. The propagation of light in the pork model is simulated by the Molecular Optical Simulation Environment (MOSE) software and the Monte Carlo multi-layered programs (MCML) program to choose the appropriate wavelength used in food quality assessment as well as optimize the placement of the reflected signal receiver. The result shows that the near-infrared wavelength in the range of 700 nm offers a high potential in food quality assessment, especially for controlling pork quality. Furthermore, the optimizing distance between the light source and the detector is within 1.0 cm. These simulation results provide an overview to design experiments and develop devices for food quality assessment based on optical techniques, especially for pork.

ABSTRACT. Fresh and spoiled pork is usually subjectively evaluated by the naked eyes of the consumers. However, the manual evaluation of pork quality has a disadvantage of the limitation of human vision and the knowledge in assessment, which is different. Therefore, a reliable method of food quality assessment is required. In this research, we adequately differentiated fresh and spoiled meat based on the characteristics of the percentage of color intensity average from the R, G, and B channels. These characteristics are obtained by using an image processing method. Experimental meat samples were stored at room temperature between 27-30 o C and imaged for 24 hours, once every 4 hours. The pH scale is used to timely compare fresh and spoiled meat. The results show the potential of using the red channel in pork quality assessment over time.

ABSTRACT. Apples (Malus Domestica Borkh) are a portion of nutritious food and are the most consumed fruits in the world. The quality of apples has become a top concern for consumers because their quality is affected by many factors such as biochemical composition (sugars, vitamin C, soluble solids) and physicochemical properties (color, firmness). The change of these factors over time affects the quality and safety of apples. The RGB histogram was extracted from the reflectance image of the apple skin to evaluate the change in apple skin during the experiment. In addition, the RGB imaging method aims to monitor the sugar content of apple flesh in real-time. The red, green, and blue histogram extracted from the RGB image is suitable for monitoring the changes in fructose, sucrose, and glucose, respectively. The results show no change in the RGB histogram of the apple skin reflectance images during the experimental time. The average luminous intensity of the apple flesh image decreased while the glucose, fructose, and sucrose content increased. The average luminous intensity decreased sharply on the second day and slightly fluctuated on the remaining days, in which the luminous intensity of the blue histogram decreased the most with 39% of the total luminous intensity compared to the remains. Fructose content increased the most due to storing ripe fruit at room temperature, causing the content to increase and starch decomposition. Research shows the potential of RGB imaging in monitoring the sugar content of apple flesh to optimize the use time and storage conditions to achieve the best quality and nutrition for consumers.

ABSTRACT. Currently, the use of near-infrared (NIR) light in medicine and biology has become increasingly necessary, especially in diagnostic imaging. Near-infrared (NIR) light with wavelengths of 700 nm to 1200 nm can obtain transilluminated images of small animals and thin human body parts. In near-infrared (NIR) imaging, strong scattering occurs in the medium of the absorbing structure. The resulting image is often blurred, and it is challenging to distinguish details like the image's depth increases. To solve this problem, the research team studied a method of scattering suppression using the point spread function (PSF) based on the Radiative Transfer Equation (RTE). The effectiveness of this method has been verified and evaluated by experiments with simulated and biological media. Clear images are obtained by deconstructing near-infrared images with a point spread function (PSF) at a specified depth. Based on the correlation with the image taken in a transparent environment, the depth and actual size of the absorbing structure can be determined. By simulating the scatter image on the MATLAB platform from the parameters of the absorption structure by convolution with the point spread function (PSF) and building an extensive data set of absorption structure images from this method for the deep learning model. Fully-Convolutional Network (FCN) model was trained with 8,000 pairs of blurred and clear images and a predefined depth. Similarly, Convolutional Neural Network (CNN) models were trained with 70,400 blurred images and the corresponding depth of the absorbing structure in the turbid medium. The application of deep learning models will help determine the actual size, de-blurred, and estimate the depth quickly at absorption structure depths from 0.0 mm to 20.0 mm from near-infrared images. The technique could potentially provide a new tool for near-infrared (NIR) imaging of animals and humans.

ABSTRACT. The automatic detection of deception behaviors has been receiving an increasing amount of attention from the research community as deception is a part of our everyday social interactions, and can play a crucial role in departments like security and criminology. In this paper, we address the identification of deceit by using single-modal approaches and give out a real-time detection program based on Deep Learning model. Among all the available modalities, we mostly focus on non-verbal modality, particularly visual appearance, gaze and action unit features. We tackle the issue using LSTM-based networks, particularly in two ways; an end-to-end CNN combined LSTM model, which is called LRCN and a method that extracts facial features separately, then brings them to classification by LSTM. The proposed methods are evaluated over the Bag-of-Lies dataset. We achieved classification accuracies in the range of 61-71%, in which the LRCN model ranked first and contributed to a deception detection program.

ABSTRACT. Breast mass classification plays an important role in breast cancer diagnosis and treatment planning. Unlike the deep neural network model, which demands a large- amount dataset, the Radiomics-based classification model maintains considerable performance in the limited dataset. This study aims to utilize the comprehensive classification pipeline of benign and malignant masses on the ultrasound image based on Radiomics features extraction and analysis. Additionally, a data oversampling technique was applied to overcome the imbalance dataset issue, and several feature selection models were performed to eliminate inadequate features. The results presented a greater performance in the ensemble learning with oversampling technique.

ABSTRACT. Sphygmomanometer or blood pressure monitor is an essential personal medical device to assist people in controlling their blood pressure to manage their health in their daily life. Elderly people are always at risk for events caused by hypertension. In the context that instant blood pressure measurements at any clinic or hospital often do not accurately reflect the patient's blood pressure readings, automatic sphygmomanometers allow users to monitor the blood pressure at home without the assistance of clinicians. With the variety of automatic blood pressure monitors, many studies have been conducted to verify whether automated products can be used as an alternative to the aneroid sphygmomanometer, which is considered as gold standard. On the other hand, not many publications mention consensus from products manufactured by the same company while their reliability can vary significantly. Therefore, the thesis presented two main objectives: firstly apply the Bland-Altman method to evaluate the agreement between the measurement values of 3 kinds of sphygmomanometers, including 2 commercial automatic devices of Microlife manufacture and 1 aneroid device; and secondly evaluate whether the two devices manufactured by Microlife used in this study can be used interchangeably. In addition to demonstrating consensus that the devices are consistent with published results and that the Microlife devices are interchangeable, the improved Bland-Altman comparison method shows that the data are more reproducible than published studies.

ABSTRACT. Cold atmospheric plasma (CAP) is interested in by researchers around the world of its special bactericidal ability .This paper wants to demonstrate the sterilization effect of cold plasma that interacts with a flat surface. After that, the sterilization procedure was tested directly on the polymer money surface and the effectiveness of the sterilization system was calculated. The sterilization device used in this paper operates with 2 setups of gases, 100% Argon or 98% Argon combined with 2% Oxy. The sterilizationtion process using the device was tested on Strains of Bacteria (Pseudomonas aeruginosa, Salmonella enterica, Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus). The result is positive with both gas setups yielded the highest efficiency up to 99.97% of bacteria killed. The paper has proved the effectiveness of the sterilization process using cold plasma on flat surfaces. It opens more potential applications of this technique in surface sterilization, especially money, in the future.

ABSTRACT. One advantage of light-based technology is that it offers non-intrusive analysis. By comprehending how light interacts with food’s tissue and examining how it is absorbed and reflected. Multispectral Camera Model (MCM) can rapidly evaluate the food quality without physically destroying it. In this work, the capturing system model that is used to evaluate the quality of food is discussed. The Raspberry Pi 4 serves as the primary controller for the MCM, controlling the LEDs and camera. The MCM contains LEDs with four color modes with spectroscopy carried out in the VIS-NIR bands which are Red (620 – 625nm), Green (522 – 525nm), Blue (465 – 467nm) and Near-IR (peak wavelength in 940nm). One at a time, specific wavelength LEDs are individually illuminated, and for each flash, a sample is simultaneously taken with a Raspberry Camera. The result is that every image captured will be represented as a 3-dimensional data cube containing details of both spectral and spatial space.

ABSTRACT. Bananas are a source of nourishment that is essential for good health. During ripening, the pigment content, starch index and sugar content of banana fruit change, providing accurate indicators for maturity classification. However, at present, banana fruits are traded according to their color stage. The purpose of this study is to visualize analysis banana color changes using a nondestructive method based on multispectral image processing since fruit quality can be assessed quickly, while the fruit being tested is still whole and marketable. This experiment designed a monochromatic camera and a set of four different optical wavelengths in VIS-NIR bands of Blue (465-467nm), Green (522-525nm), Red (620-625nm) and Near-IR (peak at 940nm) to capture the multispectral images of Musa Acuminata banana. This advanced optical detection technique (multispectral imaging) can provide the spectral reflectance of any pixel, combined with the preprocessing of a binary mask to create image segmentation, the ROIs (Region of Interest segmentation) method is then used for extracting spectral intensity data on the banana surface of each single wavelength over the ripening process of banana. With an understanding of the optical characteristics of fruit tissues (both external and internal characteristics) this research focuses on external characteristics (color components) to properly assess banana quality. The outcomes demonstrate that the behavior of resulting graphs successfully determine spectral intensity profile changes to classify the color changes as well as four main stages of classification of raw, unripe, ripe and overripe banana.

ABSTRACT. Production of pork is a daily objective for both producers and consumers. Pork quality and its economic advantages can be enhanced by using quick, non-destructive, and inexpensive monitoring techniques. This study investigates the potential of using international photos to monitor pork quality. Image processing is done using the ROI-based processing, and then using specific algorithms for food quality assessment. This allowed structural characteristics to be retrieved from the several photos of flesh tissue. A monochrome camera and four sets of optical filters covering the red (625 nm), green (525 nm), blue (465 nm), and near-IR (940 nm) spectra were employed in this work. In this research, the use of multispectral imaging modeling is validated as a non-destructive, quick, low-cost quality control tool that can effectively monitor pork quality. This offers a scientific foundation for the next study and creation of broadly applicable devices for both assessing pork quality and multispectral imaging techniques.

ABSTRACT. Despite the limited knowledge of light propagation in foods, optical techniques are becoming more common in the evaluation of food quality. Using the Monte Carlo technique, we model light propagation in pork tissue in this research. Since then, researchers have been examining how light moves through pork tissue and how multispectral imaging methods may use this information. Light can penetrate deep into the food tissue in the range of wavelength examined in this paper. The purpose of this study is to simulate the signal reception, select the appropriate wavelengths and the signal acquisition mode. The simulation results offer a general structure for system design and the creation of optically based food quality assessment tools.

ABSTRACT. Functionally graded materials (FGMs) are advanced composites whose properties are continuously variable according to their dimensions in one or more predefined directions. The application range of this material is becoming wider and wider, therefore, studies on the activity of functionally graded materials (FGMs) in high-temperature environments become more and more important and necessary. In this study, a mesh-free Radial Point Interpolation Method (RPIM) has been proposed to solve a coupled thermo-mechanical problem in functionally graded metal/ceramic plates. The most important advantage of this method is that the shape functions satisfy the property of Kronecker's delta function. Thus the essential boundary conditions are easily implemented as in the finite element method (FEM). The obtained results are compared with the reference ones from analytical solutions and finite element methods by commercial software COMSOL Multiphysics to verify the effectiveness and reliability of this method.

ABSTRACT. Functionally graded materials (FGMs) are advanced composites created using the concept of continuous material property change in one or more predetermined directions. FGMs have been used in the manufacturing of structural parts that are subjected to non-uniform functioning requirements in recent years. In a thermal protection system, for example, FGMs combine the benefits of traditional ceramics, such as corrosion and heat resistance, with this of metal, such as mechanical strength and rigidity. FGMs can be used to provide thermal barrier coatings for space applications, transportation systems, energy conversion systems, thermal-electric and piezoelectric devices, dental and medical implants, and a variety of other applications. Composites materials are widely used today, these layers are homogeneously bonded together to improve mechanical properties. However, the material change at the interface between the layers is prone to generate large contact stress. One of the solutions to overcome the disadvantages of composites are to use FGMs plate structures, it is common in engineering practice, so static analysis and dynamic analyses for FGMs plate are necessary. The meshless Radial Point Interpolation Method (RPIM) has been used based on the point interpolation method (PIM) by including the radial basis function (RPF) in the interpolation formulation and shown good performance in computational engineering. One of the advantages of this method are that it satisfies the Kronecker’s delta function, which overcomes the limitations of critical boundary conditions for the meshless method. Besides, the meshless method also satisfies the high-order continuity, overcoming this limitation that the Finite element method (FEM) cannot do. This paper presents the application of RPIM approach for static analysis and dynamic analyses of functionally graded plates which material properties vary through the thickness. Numerical examples are solved and the results are compared with reference solutions or the results of FEM given by COMSOL program to confirm the accuracy of the proposed method.

ABSTRACT. Construction in Vietnam is currently a huge investment and in the long term, it will thrive not only in the number of types of works (bridges, ports, roads, houses, water works ...) but also in an increasing scale. large, exploited in increasingly complex environmental conditions. There are many factors that affect the long term durability and usability of the structure, especially the commonly used concrete works. The phenomenon of cracking of concrete structures is inherently caused by many complex causes and is a remarkable problem in construction works. This problem has had many negative financial and human consequences around the world. This paper is the result of predicting crack formation in concrete structure. This paper will focus on research cracking criteria to predict crack formation. In addition, the finite element method performed on ANSYS APDL software is also used to evaluate the observe the crack formation. The results of the problem are also compared with the results of scientific research articles.

ABSTRACT. The problem of predicting crack propagation is always focused on because it provides information that helps us to predict the danger that the crack can cause. This paper aims at programming in order to calculate the fracture behavior of a 2D plane structure via the Extended Finite Element Method (XFEM). The application of the enrichment function, allows to reduce remeshing and obtain higher accurate results in stress and displacement fields at the crack tip. XFEM produces high effectiveness in accurately simulating the crack propagation for plate structures without increasing the number of equations and the complexity of calculating the procedure. The calculation process will use python programming language to perform.

ABSTRACT. There are so many different ways to make electricity by many available energy resources in natural such as solar, wind, tides, wave… Wave Energy Converter (WEC) is considered one promising renewable energy collection equipment. Among the WEC, the Oscillating Water Column (OWC) device is one of the most popular. Which uses the principle of rotating a Wells turbine by the airflow in the air chamber inside the device, which is generated by ocean waves. The turbine was made of various symmetric airfoils mounted with the center radially at 90 stagger angles, as indicated by the standard airfoil idea, if the airfoil is set at a point of occurrence in the liquid stream, it will create a lift power FL typical to the free stream and a draw power FD toward the free stream. A Well Turbine can work at a high rotational speed allowing the direct coupling with electrical generator. In this paper, numerical simulations are carried out using commercially available tool Fluent for fluid dynamics analysis, focus on oscillating predictions of wave, with particular attention to the behavior of the flow and focus on following the Wells Turbine’ mechanical behavior changes caused by wave.

ABSTRACT. The rotational engine is the most common mechanism in the real engineering world. During its operation with time, there is an unfavorable situation occurs when the rotator is worn gradually due to rotating motion, and eccentricity is gradually increased. The rotating unbalanced mass causes wear to the mechanism and the system should be diagnosed. This article aims to study such a typical mechanism in which a rotating unbalance is modeled, analyzed in the time and frequency domain, and considered the characteristic and time-dependent behavior. The target of the article is to investigate the responses at the various locations along the shaft and to formulate a mathematical model which could govern, trace, and monitor the levels of eccentricity to time. For a practical purpose, the case of the most twisted location of the mass and the axis of the shaft are considered in which the horizontally curved beam is the most unfavorable one; a finite element model is developed to obtain the responses of the system at an instant duration. These responses are considered to be the most unfavorable ones that the system could experience. A finite element model is developed to obtain the responses of the system at a specifically arbitrary time. The solution withdrawn from the analysis could help to develop a plan of maintenance for the system.

ABSTRACT. Electric Motorcycles (EMs) are proving themselves to be efficient, low-polluting vehicles and a worthy replacement for gasoline-powered vehicles in Vietnam. This paper aims to study and introduce the road test procedure for EMs riding in Ho Chi Minh, Vietnam. The performance characteristics and energy consumption efficiency of EMs are evaluated using various input values. To reach this aim, two electric motorcycle prototypes were investigated through mathematical modeling and road test. Mathematical formulas clearly define key variables of interest such as vehicle mass, rider mass, speed, and frontal area. These are recorded by monitoring and measuring equipment listed with a technical description. The procedure starts with preparation, and inspection and ends with data analysis. Finally, case study applications in Ho Chi Minh, Vietnam applied and evaluated the obtained results. Energy consumption is 157 - 265 Wh/10km with a 21 – 27 km/h speed profile and powertrain efficiency with the 27 km/h profile is 87%. The experimental results like manufacturer's specifications and research reports on EMs. The next development direction is to research and evaluates rider behavior which is an important factor affecting the performance of EMs.

ABSTRACT. Machine learning is one of the most widely used techniques to solve problems. Artificial neural networks (ANNs) are the state-of-the-art algorithmic architecture for machine learning tasks. Artificial neural networks have been applied to solve a great variety of problems. It seems not easy to solve differential equations for physical and engineering, namely mechanical problems. Physic - Informed Neural Networks (PINNs) are applications based on artificial neural networks. It is a type of universal function approximator that can embed the knowledge of any physical laws that govern a given data-set in the learning process and can be described by partial differential equations. Furthermore, it can be used to approximate the function of problems from differential equations. This paper investigates the application of machine learning in Physical and Engineering, namely solving beam structure using Physic - Informed Neural Networks. Then compare this result with results solved by analytical and numerical solutions.

ABSTRACT. LabVIEW - Laboratory Virtual Instrument Engineering Workbench is a graphical application development environment developed by National Instruments Corporation based on the dataflow representation of the “G” language [1][2]. LabVIEW is implicitly multithreaded and has high level functions for communication/synchronization, allowing it to be used as a programming language for control/command and soft real-time applications. From the above features, LabVIEW is a useful tool for designing User Interface and real-time system control. The purpose of this paper is to present a case-study in the application LabVIEW to control real-time system by using the fearture of LabVIEW that is multitasking, parallel processing of many operations, many data sources to control multiple devices at the same time. Beside that, using LabVIEW to design an user interface which is friendly, easy to use, fully funtional such as control, measure, operation,… is also a topic of this paper. Understanding and using typical features of LabVIEW helps designers and operators easily manipulate, save time, and are convenient in use.

ABSTRACT. This paper presents a static analysis of Functionally Graded (FG) beams using the Finite Element Method (FEM). Variation of stress according to mechanical properties of each material layer of FG beams under static loading is studied. The supported beam is considered. The FG beam's material properties are position-dependent and graded in the thickness direction. For this purpose, simulation models are developed in the commercially available ABAQUS software. Simulation results are compared with results from other studies

ABSTRACT. A nonlinear beam element for large displacement analysis of microbeams and microframes is derived in the context of the corotational formulation. In order to account for the micro size effect, the modified couple stress theory (MCST) is adopted in conjunction with Timoshenko beam theory in derivation of the element formulation. The expressions for the local internal force vector and the tangent stiffness matrix are obtained by using the hierarchical functions to interpolate the displacements and rotation. Newton-Raphson iterative method is employed in combination with the arc-length technique to solve the nonlinear equilibrium equation and to trace the equilibrium paths. Various microbeams and microframes are analyzed to show the influence of the size effect on the large deflection behavior of the microstructure. The obtained result reveals that the size effect plays an important role on the behavior of the microstructure, and the displacements are overestimated by ignoring the size effect. A parametric study is presented in detail to highlight the influence of the material length scale parameter on the large displacement behavior of the microbeams and microframes.

ABSTRACT. Dynamic finite element analysis of microbeams under a moving mass is presented in the basis of a refined third-order shear deformation theory. The modified couple stress theory (MCST) accounting for the influence of the size effect is adopted to derive the mathematical formulations. A two-node beam element with ten degrees of freedom is derived from the energy expressions and employed to construct the discretized equation of motion for the microbeams. Dynamic characteristics, including the time histories for mid-span deflections and dynamic magnification factors (DMFs) are computed with the aid of the implicit Newmark method. Numerical results reveal that the size effect plays an important on dynamic response of the microbeams, and the DMFs are overestimated by ignoring this effect. The effects of the loading parameters as well as the beam aspect ratio on dynamic behavior of the microbeams are studied in detail and highlighted.

ABSTRACT. The article studies the flight trajectory of the priming wire launcher, calculates the external projection equations to determine the parameters of the launcher on the flight path. Using numerical methods, building a system of differential equations with CAD software to calculate flight trajectory to ensure stability on the flight path, to achieve launch range and accuracy as proposed.

ABSTRACT. Currently, in the world in general and in Vietnam in particular, the number of patients undergoing hip replacement surgery increases every year. Thanks to this technique, the patient's hip function is restored, and the quality of life is significantly improved. However, despite many advances in the study of the biomechanics of artificial joints, in terms of shape, structure, and replacement materials, the durability is not high, and the lifespan of artificial joints is short, leading to the need to replace them with the expensive cost. One of the reasons for this risk of replacement is the fatigue, loss of strength, and deformation of the artificial joints causing looseness and dislocation. In order to understand more as well as to suggest ways to solve practical problems or to apply artificial hip effectively, the research will be carried out by finite element method to serve as a premise for future development. The objective of the thesis is to analyze the biomechanical characteristics and movement mechanism of the hip joint and analyze the mechanical behavior of the artificial hip. Critical points and domains are developed and simulated into 3D models for evaluation and interpretation. Finite element analysis was verified by experimental testing and kept clinical relevance used to decide on the best optimal hip design. In addition, improving with deeper stress analysis of different design elements creates the ultimate optimal model.

ABSTRACT. Auxetic materials and structures are lightweight, which not only complies with the development trend of structural weight reduction and performance improvement but also with the development trend of auxetic materials as highly effective energy-absorbing materials. The lightweight investigation of metal elliptically perforated plates was conducted using experimental and computational methods in this work. The impact of the quantity of material removal on the structure's Poisson's ratio and energy absorption was then further discussed. This study considers the construction of compact auxetic metamaterials based on elliptic perforated plates to enhance the energy absorption capabilities of auxetic metamaterials. The mechanical characteristics of the novel metamaterials, according to experimental and numerical results, are essentially unaltered. Still, specific energy absorption is significantly improved because there is less material used overall and the optimized materials are distributed to the areas that need them the most. This study systematically examines the effects of the hole radius in the design area on the mechanical characteristics of the metamaterials as well as the significance of the materials in various design area locations on the overall stability of the structure. Then, using finite element analysis, two different types of stiffened metamaterials are created, and their mechanical characteristics are compared to those of the more common elliptic perforated plates.

ABSTRACT. The need for improvement of a dentures testing prototype created by the Centre of Computational Mechanics laboratory in 2020 has led to this research. This paper presents a device to simulate the chewing motion and bit-ting process of the lower jaw with many improvements compare to the first version. The device is designed with a jaw attached to the denture. The lower jaw will be held and perform the biting process by two degrees of freedom gear mechanism. The main design of the device is still based on and follows the restriction of human jaw geometry. To be specific, the distance between temporomandibular and tip of the lower jaw foretooth when the jaw is close must be maintained at approximately 92,7 mm. The transmission mechanism provides two motions type for the lower jaw: open-close jaw movement and side-biting movement. The structure of the device allowed the maximum crushing force of each side to reach 50 kgf. This paper uses the finite element method to calculate and optimize components of the device by ANSYS software, then the implementation of the model will be carried out. The main loadbearing component calculated is the durability of the lower jaw attachment having a yield stress of 0,5643 MPa. The yield stress value of the components is less than the yield stress of plastic PLA material 70 MPa, the components will meet the durable operation of the device. The part of the device is manufactured by 3D printing technology with PLA material. BLDC motor FBLM440C-GF and gearbox GF4G30 will be used to provide movement for the whole system and controlled with two sets of Discovery kit STM32G431CB MCU. A load cell is used to collect data on the acting force on the upper jaw. The model was built with three basic testing phases (opening, closing, and side bitting) and a graphic user interface which makes the device more friendly to users. The device is successfully built with mechanisms of the lower jaw that allowed the movements to correspond to the mean chew-ing force, which helped doctors have multiple options to examine dentures. In the future, we will improve software, frequently update user requirements to build more complex motion trajectories as well as improve the precision of the device.

ABSTRACT. The gearbox is the main component in a common transmission system. The increased the mechanical power capacity of gearboxes, the bigger the thermal power. To achieve a balanced system, the gear system needs extra cooling, with some common methods such as using a cooling system, and automatic oil cooling ... But for the optimization of the cooling system, it is impossible to evaluate the working efficiency of the methods. Therefore, in this study, the thermal performance of the transmission gearbox will be analyzed by the finite element method, showing limitations and overcoming methods for the cooling system of the gearbox.

ABSTRACT. This paper presents a method to determine the mechanical properties of bubble-like foamed materials by describing the correlation between the porous structure and the linear elastic mechanical behavior of an idealized model of the open-cell porous structure. This method forms a structure based on Kelvin's conjecture about the bitruncated cubic honeycomb structure and Voronoi theory to describe the random occurrence of pores inside the material. Thereby determining the influence of porosity and pore size on the mechanical properties of the material. In addition, the Finite Element Method (FEM) is used in this research to solve the tension/compression tests with the sample in many different cases to determine the relationship between stress and strain. However, because this model has been limited in some other factors to reduce the problem's complexity, that limits the feasibility of the model to predict the mechanical properties of materials. Therefore, the equations derived by this method will be compared with experimental data on well-described porous materials, to verify the reliability of this method.

ABSTRACT. This paper presents a static analysis of Sandwich Functionally Graded Material (FGM) beams structure under static thermal loads and static mechanical loads. The structure of the beam is a sandwich structure. The material properties of Sandwich FGM beams are developed based on the principle of continuously changing material properties according to a defined rule. Analysis of mechanical behavior of Sandwich FGM beams structure based on Euler-Bernoulli beams theory and Timoshenko beams theory. Apply two beams theories to the illustrative problem, thereby giving the appropriate theory for each case.

ABSTRACT. Bài báo này được thực hiện với mục đích nghiên cứu ảnh hưởng của độ rỗng vi mô đến khả năng khuếch tán ion clo của đá xi măng. Để dự đoán hệ số khuếch tán ion clo hữu hiệu, đá xi măng có thể được mô phỏng bởi các phương pháp đồng nhất hoá cơ học vi mô dựa trên nghiệm của bài toán Eshelby coi đá xi măng bao gồm các pha hạt hình cầu không khuếch tán được phân bố trong các pha nền có khả năng khuếch tán. Kết quả của bài toán mô phỏng là hệ số khuếch tán hữu hiệu của đá xi măng là một hàm phụ thuộc vào tỷ lệ thể tích của vi lỗ rỗng và hệ số khuếch tán trong dung dịch lỗ rỗng. Các kết quả giải tích thu được sẽ được so sánh với các kết quả thực nghiệm đã được thực hiện trong các công bố trước đây.

ABSTRACT. An extended meshfree method for analyzing cracked plates based on Reissner-Mindlin theory is presented in this paper. The Reissner-Mindlin theory is a simple plate formulation with the assumption of first-order shear deformation and is suitable for the relatively thick plates. In modelling plate structures, the meshfree method is an alternative to the conventional finite element method (FEM). Among a variety of meshfree formulations, the radial point interpolation method (RPIM) is chosen in this study due to the satisfaction of the Kronecker delta property. The essential boundary conditions, therefore, are easily imposed in the RPIM. The shape function derived from RPIM is employed to interpolate the field variables. An extended RPIM formulation is used to model the crack segment without explicitly defining it in the discretized domain. The discontinuity due to the crack is defined by extrinsic enriched functions, particularly, the jump in the displacement field on two sides of the crack is modelled by the Heaviside function, and the stress singularity near the crack tip is described by the asymptotic enriched function. The stress resultant intensity factors (SRIFs) are an important feature in fracture analysis of cracked plates that require to be evaluated. In this study, the SRIFs are evaluated through the interaction integral approach. The obtained SRIFs are shown in the paper through many numerical examples for comparison purposes. The numerical examples show the accuracy of the present approach. The obtained results are compared with analytical solutions and other numerical methods.

ABSTRACT. This paper investigates the fracture behavior of plates with through-thickness crack by using the extended concept of the Radial Point Interpolation Method (RPIM). The attractiveness of the RPIM shape functions is the satisfaction of the Kronecker delta property providing direct imposition of essential boundary conditions. In the extended concept, the jump in deflection and rotation fields caused by crack, also the stress singularity near the crack tip are described by adding enriched functions to the interpolation equation. Particularly, Heaviside function and asymptotic enriched function. For numerical integration, the Cartesian Transformation Method (CTM) is employed. No integration background cell is required in CTM, this technique transforms a domain integral into a boundary integral and a 1D integral. For analysis of discontinuous problems, in this study, the distribution of integration points is manipulated to avoid the discontinuity caused by crack segmentation. Therefore, no subdomains are required, unlike other reference CTM studies. To achieve that, a virtual boundary is introduced that represents the discontinuity such as holes or cracks. This also matches the concept of the extended approach that no explicit discontinuity exists in the geometry, instead, the discontinuity is modelled by mathematics equation. The Stress Intensity Factors (SIFs) of the cracked plate are evaluated through the interaction integral technique. The efficiency of the proposed method is illustrated through various numerical examples. The accuracy of the obtained results are compared with other available numerical solutions and analytical solutions.

ABSTRACT. The virtual element method (VEM) is a numerical method developed from the finite element method for approximating the results of partial differential equations. The idea behind the virtual element method is that one do not need to explicitly represent the form function and it is no longer approximated by Gaussian integrals leading to many advantages over the finite element method. In this paper, author present the application of VEM for elastic problem solving. The computational program is build by using Matlab code. The numerical examples are performed and compare with reference solution to verify the accuracy of the proposed approach.

ABSTRACT. The improvement of living environment in homes and workplaces is also essential. Nowadays, many countries around the world have implemented many house models that apply natural ventilation to the house instead of artificial air conditioning system, because natural wind is better and also feels more comfortable. Therefore, the study of controlled natural ventilation architecture is necessary. In this paper, the author uses Ansys software, based on the finite volume method, to simulate the natural ventilation process for the office building of Viet Cuong company, Tan An city, Long An province.

ABSTRACT. Determining cable tension in long-span structures as cable-stayed bridges is necessary for inspection and structural health monitoring. The one of solutions for this problem is vibration measurement. However, it may not be accurate when parameters such as the sag, damping, and bending rigidity of cable are significant. On this page, the differential equation for the cable vibration is taken into account, including damping and bending rigidity in the cables. Then, assumptions of boundary conditions are simplified and expressions showing the relationship between frequency and tension are obtained. A practically applied procedure to determine cable tension through measured frequencies is proposed. The proposed procedure is verified by some cables of the Phu My bridge in Ho Chi Minh City.

ABSTRACT. Today, medical imaging is extremely necessary because it provides physiological and anatomical images of the human body indirectly, helping doctors to give more accurate diagnosis results. There are many different imaging methods and techniques such as Magnetic Resonance Imaging (MRI), Computed Tomography Scan (CT- Scan), and Ultrasonic. Each approach has different pros and cons that affect both patients and healthcare professionals. In order to solve the above problems, the idea is to develop an imaging method in all areas of the body based on impedance tomography (EIT), which is a reconstructive imaging technique based on a specific region in the human body based on the electrical conductivity of biological tissues completely harmless to the body and compact design with low cost. Currently, EIT is being used in the diagnosis of lung function, development and monitoring of activities in brain pathology, studies only investigate with low conductive tissues and are limited in different locations. other parts of the body. Therefore, the thesis topic was developed based on these studies, and we will investigate in the thigh part of the human body because this place has many layers of tissue with different electrical conductivity. The content of the thesis is to build a 3D model of the human thigh from a dataset of MRI images called DICOM images built on MIMICS software, set up an EIT measurement system with 16 electrodes to simulate current propagation to the tissues, these processes are performed on COMSOL Multiphysics simulation software, the data collected from the simulation results is a data set of voltage values for the purpose of reconstructing the image at the horizontal position where the electrode was set up using the EIDORS tool. Image results after reconstruction will compare with the original DICOM data to determine bone position before and after processing. The construction and simulation process is the first step in developing an EIT system in different locations on the body. This process lays the foundation for the device design and future research.

ABSTRACT. Different heating rates are used to study the melting process of zigzag hexagonal Boron Nitride via molecular dynamics simulation. Models containing 10000 atoms are heated up from 50 K to 7000 K via Tersoff potentials to have an entire picture about the structural evolution of zigzag hexagonal Boron Nitride upon heating. Various thermodynamic quantities are calculated to study the mechanism of melting process as well as the structural evolution, such as, the total energy per atom, the heat capacity per atom, the radial distribution functions. The phase transition for both heating rates in this work exhibits the first order. The melting point of models depends on the heating rates in the range of this study.

ABSTRACT. Otitis media is a common infectious disease in the world in general and Vietnam in particular. To improve diagnostic accuracy in these pathologies, the important factors are the assessment of the characteristics of the tympanic membrane (TM). In this study, we focused on extracting the tympanic membrane from the middle ear image. A cross-polarized system was used to minimize glare but retain the information to quantitatively the feature of the tympanic membrane. Endoscopic images of the ear were captured with two modes non-polarized and polarized light sources. Then, the active contour algorithm is applied to segment the tympanic membrane region including the handle of the malleus.

ABSTRACT. In this study, porous carbonate apatite (CO3Ap) was prepared using bioapatite and calcium sulfate hemihydrate via salt leaching method. X-ray diffraction (XRD) and Scanning electron microscope (SEM) were used to characterize phase composition and structure. The results indicated that pure CO3Ap block consisting of interconnecting pores with pore size about 100-300µm of diameter could be obtained. Mechanical strength was evaluated in term of Dimentral Tensile Strength (DTS). Porous CO3Ap had a mean DTS value of 418.6  9.71 kPa and an average porosity of approximately 40%. As a conclusion, CO3Ap with low crystallinity and interconnecting porous structure is advantageous on bone regeneration as being a useful material for application to repair bone defect.

ABSTRACT. Cervical disease is one of the most common diseases affecting women worldwide. The signs of this pathology are usually the appearance of an atypical epithelium or an irregular vascular shape depending on the severity of the lesion. The shape of blood vessels on the surface of the cervix is one of the important signs for doctors to diagnose pathology. Previously, the observation was proceeded by the naked eye through the colposcope. However, this method has many limitations because the mucus affects the doctor's field of view, leading to difficulties in determining the shape and density of blood vessels. In this study, colposcopic images were taken under polarized light to help reduce reflections from the surface to support more efficient image processing steps. After applying different pre-processing methods, Niblack and Sauvola Threshold were applied for vascular segmentation. Segmented blood vessels were then evaluated using the Sensitivity and Specificity. The result shows that the method combining the pre-processing method based on the different absorption properties of the cervical epithelium with Sauvola threshold gives high sensitivity and specificity, which can create a premise in cervical vascular identification studies, aiming to support assessment of cervical precancerous lesions based on observation of vascular pattern.

ABSTRACT. In this study, TiO2 nanowires on TiO2 nanotubes arrays (TNWs/TNAs), Au-decorated TNWs/TNAs nanostructures are designed and fabricated as a new type of photoanodes for photoelectrochemical (PEC) water splitting. The TNWs/TNAs was fabricated on Ti fold by anodization using an aqueous NH4F/ethylene glycol solution, while Au nanoparticles (NPs) and Au nanorods (NRs) were synthesized by Turkevich methods. We studied the crystal structure, morphology, and PEC activity of four types of nanomaterial photoanodes, including TNWs/TNAs, Au NPs- decorated TNWs/TNAs, Au NRs- decorated TNWs/TNAs, and Au NPs-NRs- decorated TNWs/TNAs. The samples exhibited pure anatase phase of TiO2 with (0 0 4), (1 0 1), and (1 0 5) preferred orientation. The samples obtained a well-defined and uniformed structure of TNAs/TNWs; and Au NPs (size of ~15 nm) and Au NRs (width of 15-20 nm and length of 64 – 100 nm) were primarily deposited on TNWs. The photocurrent density (J) of these nanomaterials was in the range of 200 – 350 µA/cm2, in which Au NPs-NRs- decorated TNWs/TNAs obtained the highest J value of 350 µA/cm2 owing to the enhanced light absorption in the visible - infrared range of the Au NPs and Au NRs. Decoration of Au onto TiO2 offers a significant enhancement in the PEC activity due to the surface plasmon effect occurring at Au nanomaterials. Furthermore, Au NPs-NRs- decorated TNWs/TNAs exhibited excellent photocatalytic activity in degradation of methylene blue with a high reaction rate constant of 0.70 ± 0.07 h-1.

ABSTRACT. In this study, we evaluated the effect of Lead (Pb2+) concentration on the development of zebrafish by mating method. Therefore, we reared zebrafish for fish embryos by mating, and divided the embryos into two groups. Group 1 fish embryos reared in normal environment were used as controls. Group 2 is a group of fish embryos reared in environments with different lead concentrations. We observed and compared the differences between the 2 groups of fish and the differences between the individuals in group 2 in terms of parameters such as survival rate, time span, accumulation level (Pb2+). The results only show that heavy metals in the aquatic environment are the cause of fish growth retardation, shape change and reduced survival rate of fish.

ABSTRACT. In this study, we evaluated the effect of CADMIUM concentration (Cd2+, one of the typical heavy metals) on the development of zebrafish embryos by fish mating method. We controlled fish embryo samples developed in normal medium and other samples grown in media contaminated with different concentrations of Cadmium. Thereby evaluating parameters such as mutation, heart rate, survival rate, ... of fish embryos according to different concentrations and from there, it is the basis for assessing the influence of heavy metals on aquatic animals and human being is more and more profound and perfect.

ABSTRACT. In this study, we assessed the effect of copper on zebrafish behaviour using the method of fish breeding combined using LED As the fact that, in recent years, due to technical development and population growth, the environment is increasingly polluted by heavy metals, which originate mainly from industry and transportation. Sources of pollution caused by human activities such as copper used in batteries, batteries, some types of electrical equipment, in addition lead is also used as a colorant, stabilizer or binder. … When exposed to certain levels of copper, it causes nervous system damage and causes brain disorders in humans and animals. Exposure to high levels of lead causes mastopathy in animals It is worth noting that fish embryos have been of interest to risk assessment procedures because of their high sensitivity to polluting species and their ecological relevance. In this context, an increasing number of studies are proposing full-scale sediment exposure bioassays using fish embryos. Thus, the lethality and teratogenic effects of the experimental sediments were evaluated using classical criteria such as embryo survival, hatching rate, growth growth retardation, heart rate and developmental abnormalities Since then, it is the basis for assessing the influence of heavy metals on aquatic animals and humans.

ABSTRACT. Since the outbreak of SAR-CoV-2 infections in Wuhan (China), researched communication is on race to investigate the specific antiviral drug for Covid-19 treatment. The 3CLpro main protease is elected as a protein target for preventing SAR-CoV-2 viral replications. In this study, we hereby aim to clarify the efficiency of Penciclovir in inhibiting the mechanic of 3CLpro target of SAR-CoV-2. Using docking simulation and molecular dynamic simulation (SMD), the interaction of Penciclovir with 3CLpro target was investigated. The results show that Penciclovir strongly interacts with 3CLpro target of SAR-CoV-2, and the non-binding interaction plays a more important role than hydrogen bonding in the steady state of the receptor-ligand conformation.

ABSTRACT. A series of density functional theory calculations were performed to understand the bonding and interaction of hydrogen adsorption on two-dimensional silicon carbide. The converged energy results pointed out that the H atom can sufficiently bond to 2D SiC at the top sites (atop Si and C), of which the most stable adsorption site is T¬Si. The vibrational properties along with the zero-point energy were incorporated into the energy calculations to further understand the phonon effect of the adsorbed H. Most of the 2D SiC structure deformations caused by the H atoms were found at the adsorbent atom along the vertical axis. For the first time, five SiC defect formations, including the quadrilateral-octagon linear defect (8-4), the silicon interstitial defect, the divacancy (4-10-4) defect, the divacancy (8-4-4-8) defect, and the divacancy (4-8-8-4) defect, were investigated. The linear defect (8-4) has the lowest formation energy and is most likely to form. This study could be an interesting note for future applications of hydrogen energy.

ABSTRACT. By using the Molecular Dynamics simulation (MD) method, this study aims to show the influences of cooling rates on the solidifying temperature of the water inside a single-wall-carbon-nanotube (SWCNT) under different ambient pressures. We first created different systems with different tube diameters, then we cooled the systems from 300 K down to 200 K under different ambient pressures to observe the behavior of water. Our results showed that the more rapid cooling rate of the systems creates more disruptive and dramatic phase transitions that localize in specific ranges of temperature. Moreover, we also found that the lower pressures correlate to the more dramatic phase transitions of water molecules, regardless of the cooling rate. This study generally provides more insight into water behavior in the SWCNT with variations in ambient conditions.

ABSTRACT. Diabetes is a common chronic disease in most countries of the world and is one of the challenges for the medical field because of the rapidly increasing number of diabetic patients. Harmful effects on the body give rise to many other diseases and threaten the patient's life. To prevent complications of diabetes, we must continuously monitor blood sugar levels in the body by using today's popular meters to measure the patient's blood, which is highly accurate but painful, costly, and dangerous in the spread of infectious diseases. Furthermore, the patient's continuous measurement leads to finger damage in the long run. This paper uses the 940 nm wavelength with transmission mode to design a non-invasive blood glucose measurement model. When infrared light passes through the finger, the light intensity will change received and calculated to give a blood glucose signal on the screen. As a result, the regression line was built from measured data at the index finger of 30 people, with the R squared value of 0.7515. In Clarke's error grid analysis of 30 samples, all values are in region A. In other Clarke's error grid analyses of 300 samples, there are 92.67% values in zone A, and 7.33% are in zone B. Compared with the VivaChek blood glucose meter, the average accuracy is 4.5172, and the average standard deviation is 1.5183.

ABSTRACT. The importance of biometric security in modern society is ever-growing. Also, biometrics is constantly innovating in technology to create more secure products. However, the standard commercial palm vein authentication base on a two-dimensional (2D) palm vein pattern image could be fabricated. Using near-infrared (NIR) light with 700-1200 nm wavelength, images of veins in the back of a hand can be obtained. They are two-dimensional (2D) images of internal absorbing structures in a scattering medium. On the other hand, a three-dimensional (3D) image is obtainable using filtered back projection (FBP) from that developing a lower budget, less time consuming by using stereo images to 3D reconstruct. In this study, self-developing experimental images of three objects in a scattering medium are then reconstructed into 3D by FBP using 20-degree and 340-degree angles to construct 3D by stereo vision. Then, experiment using LED at 940 nm wavelength on palm hand captured by the stereo camera, and stereo images reconstruct the 3D result. As a result, 3D images show more information about three objects when using FBP than stereo vision. In addition, the 3D stereo result shows the more evident shape of three objects and regions of interest (ROI). This technique can provide a new tool for the NIR imaging of palm vein authentication.

ABSTRACT. Today, according to medical experts, temperature management in the operating room, and infusion solutions need to be maintained at a temperature close to normal for patients to recover from surgeries. Hypothermia is a common problem that occurs 20% - 90% in surgeries. Intraoperative hypothermia is defined as a body temperature below 360C occurring at any time during and after surgical anesthesia. Many studies in the field of anesthesia for general surgery and orthopedic trauma have confirmed that intraoperative hypothermia causes a series of complications such as wound infection, death due to cardiovascular complications, and coagulation disorders. This lead to increased blood loss during surgery, requiring the use of many drugs, prolonging the recovery time, and leading to an increase in treatment costs. Therefore, it is necessary to limit heat loss and provide more heat to the patient. The model in this topic is designed based on the mentioned needs and with reference to the advantages of commercial devices in practice. Along with the desire that the model is designed to be compact, easy to manipulate, low cost and can be used commercially.

ABSTRACT. Tibia fractures or osteoporosis of the tibia cause difficulty in walking and living for the patient. The tibia is an important bone of the lower extremities, which takes the longest time to recover, and the activity of the legs is also relatively limited. This has a significant impact on the daily life of the patient. Over the years, studies on the application of low-power semiconductor lasers in the treatment of bone regeneration have been conducted. Low level laser light has the effect of tissue regeneration, pain relief, and inflammation reduction. In this study, we used the Monte Carlo method to survey the impact of lasers on the tibia area with 4 wavelengths: 633 nm, 780 nm, 800 mn, and 940 nm. Next, we implement the curve fitting method using the parameters obtained from the Monte Carlo simulation results at different wavelengths. The results showed the relationship between energy and the beam radius by depth with a RSME of 2.62% and 1.32%, respectively. We hope that the study will support the rapid survey of the impact of laser beams on other areas that help optimize the parameters in treatment.

ABSTRACT. The knee joint plays an important role in supporting and helping the body move, so it must constantly work with high intensity. Therefore, the knee joint is easily injured if not be taken care of well. Nowadays, people often encounter knee problems, especially knee osteoarthritis. Osteoarthritis of the knee joint is a disease that seriously affects human health and life. In recent years, the biomedical field has made rapid strides, possibly leading to the application of low-level laser therapy for the diagnosis and treatment of diseases. In order to obtain positive results when using a low-level laser beam on the knee joint, it is first necessary to understand the propagation mechanism of the laser beam in the biological tissue of the knee joint. Many studies have demonstrated that Monte Carlo method can be used to solve various physics problems of light propagation in biological tissues. Therefore, the Monte Carlo method helps to choose the appropriate wavelength, dose and interaction time in low-level laser therapy. This paper uses the Monte Carlo method to simulate the propagation mode of the laser beam at 4 wavelengths (633 nm, 780 nm, 850 nm, 940 nm) when interacting with the knee joint.

ABSTRACT. Stroke is the second leading cause of death and disability worldwide. In particular, hemorrhagic stroke has a much higher mortality rate than ischemic stroke. The rate of stroke in Vietnam is increasing and tends to be younger. Treatment methods for hemorrhagic stroke always have risks or are not definitive. Low-power laser therapy is emerging as a non-invasive, low-cost treatment. There have been published studies on the therapeutic efficacy of hemorrhagic stroke in animals. However, the study of treatment in humans is limited because the selection of projection parameters is very complicated and there may be side effects when direct irradiation. Therefore, the use of the Monte Carlo simulation method is of great interest because the method is easy to implement and has high accuracy of the investigated parameters. To perform the simulation, it is necessary to understand the overview of the interactions of light with biological tissues, the mechanisms of action of low-power lasers, the Monte Carlo simulation method, the simulation programs "mcml. exe", "conv.exe". Simulation results the energy distribution at the 10-4 W/cm2 power density isotherm shows the energy distribution of photons across tissue layers, especially the hemorrhagic layer.

ABSTRACT. If cardiovascular diseases are the leading cause of death, the leading cause of disability is musculoskeletal diseases. And lumbar spondylosis is one of the most common symptoms related to osteoarthritis. In addition to treatment methods such as medication, physical therapy or surgery, nowadays the uses of laser and optics are increasingly common in the medical areas, especially low-level laser therapy. This is an alternative non-invasive treatment and the light with the wavelength of 600 nm to 1100 nm could penetrate and propagate deep in biological tissue. The interaction mechanism of photons with tissues is an important factor that directly affects the effectiveness of treatment while optimizing light delivery is critical to accurately stimulate the biological effects inside the biological tissue. This paper describes the simulation results of low level laser propagation from skin surface at the lumbar spine with four wavelengths (633 nm, 780 nm, 850 nm, and 940 nm) by the Monte Carlo method.

ABSTRACT. HVAC system (Heating Ventilating and Air Conditioning) controls temperature, humidity, infection limits, and cleanroom pressure. However, filters can eliminate tiny particles such as microorganisms from the air that high-pressure drop in the HVAC system, causing increased consumable power. In the last few years, designing a disinfection system with optical filters has been prioritized to optimize operational cost and installation. In-tube devices usually consist of one or more UV lamps. The bacteria passing through the irradiation field are inactivated if the exposure time is long enough and the intensity is high enough. The efficiency of the sterilization process is influenced by many factors: susceptibility of bacteria, air velocity inside the tube, temperature, humidity, and reflectivity of the duct surface. This research shows how to use the flow dynamics method (CFD) to investigate the sterilization ability of the system, thereby providing a model of UV lamp arrangement in the tube to achieve optimal efficiency.

ABSTRACT. This paper aims to provide a solution to the mentioned problem, a way to optimize planning and the execution of maintenance, with the test size being 320 patient beds, by developing a 3-frame model using QFD (Quality Function Deployment) to create a priority assessment program. The priority score is based on risks, mission, and maintenance. Therefore, the traditional use of QFD can end up overridden prioritized decisions. To improve the original model, Fuzzy Logic is integrated into the model. The model helps identify essential criteria as well as optimize the budget required for maintenance. From there, it assigns priority scores and sorts the equipment based on them to create the most suitable maintenance schedule.

ABSTRACT. Acne is one of the most common skin diseases today and leaves a bad influence on the psychology of the patient because of scars and permanent deformation on the skin. Low-level laser phototherapy methods have been proposed for research in the treatment of acne. This paper investigates the inhibitory ability of blue laser (532nm) at a power of 5mW lighting directly on petri dishes with C. acnes – causing acne vulgaris. Our team conduct the survey in 3 exposures 48 hours apart with 4 times intervals (5 minutes- 10 minutes - 20 minutes - 30 minutes) to find the most suitable course of treatment. With the results of the number of bacteria that obtained on the surface of the petri, exposes 3 irradiation for 30 minutes, it reduced by 82% compared to the sample. Therefore, the result indicate that this is the most effective period to achieve treatment for a course of 3 times irradiate 48-hour-period

ABSTRACT. Nowadays, the gap between traditional engineering and medicine sciences are slowly filled. Thank to the development of technology and sciences, medical instrumentation are not only used for diagnostic but also be a part of clincal protocal. Along with that, when we combine biomechanics and biomaterials together with electronics, amputees can moving their limbs again with smaller, lighter and more convinients machine. Although there are ideas about physical medicine and rehabilitation technologies, prosthetic limbs are still not widely used due to the commercials prices. Therefore, we used solidworks to model robotics arm as a initial step to develop a product meets the basic engineering requiredments and cost-effective

ABSTRACT. Multiple cognitive functions are involved in the process of decision-making. The vital in human daily life has been a rising demand for the ability to foresee the causes or impacts of culling. It has broad applications in behavioral psychology and neuromarketing research. This study shows the elements that influence the decision-making process through the ratio of brain region power spectral density (PSD) in electroencephalography (EEG) signals. For feature selection, the Sequentialfs algorithm is utilized, and the output of that step is fed into the classifier. Two classification algorithms, Support Vector Machine (SVM) and Linear Discriminant Analysis (LDA) are also put on the scale to compare performance statistically. The results show that the model using LDA classifier achieves 84.14%, better than SVM’s 12.42%.

ABSTRACT. Hands are a part of the human body, an important part that helps people to hold hands. The position of the hand at the end of an arm, where a large number of nerves help control actions from simple to complex. The fingertips are also the location that receives the most haptic feedback to support positioning. In case of a hand injury, it can cause many difficulties in daily life. By researching and manufacturing equipment to support physical therapy on such criteria as compactness, and low cost. We hope to help people with hand injuries quickly recover and restore a normal life rhythm.

ABSTRACT. Parkinson’s disease (PD), or simply Parkinson’s is a long-term degenerative disorder of the central nervous system that affects mainly the motor system. The most obvious early symptoms are tremors, rigidity, slowness of movement, and difficulty walking. The purpose of this research is to build a prototype of a spoon that senses the movement of the hand of a person with Parkinson’s disease. It provides a counter-movement to the shaking action of the patient’s hand, so that they do not spill their food. With this method of viewing hand movements acts as a feedback signal to a microcontroller that operates two servos that provide counter-clockwise motion.

ABSTRACT. In the musculoskeletal system, the spine determines the life and movement of humans as well as that of all other vertebrates. The degenerative spine usually begins with damaged joints of the vertebral bodies, neck herniated disc, ligament, and then gradually occurs degeneration of the vertebrae, causing neck pain, especially when moving the neck area. Nowadays, along with the development of the biomedical field, low-power laser therapy is more prominent in its applicability in diagnosis and treatment. This paper describes the simulation results of low-level laser propagation from the skin surface to the cervical vertebrae with four wavelengths (633 nm, 780 nm, 850 nm, and 940 nm) by the Monte Carlo method. These simulation results are the base for analyzing the impact of near-infrared light and developing the low-level laser therapy device, that could be used in clinical for treating the degenerative spine.

ABSTRACT. The hand is one of the most important human organs, located at the end of the arm. They have the function of grasping, creating precise movements and meeting the creative needs of people. The fingers in a hand contain many of the nerve endings in the body, providing the largest localization and richest tactile feedback in the human body. In addition to the fingers, the hand also has a system of bones, muscles, ligaments and joints. In that case, we created a model call “Model for measuring and training muscle tone of the hand” will try to make products suitable for the needs of users, reduce costs and be more compact. Help users have a good experience and stable accuracy. In addition, it also offers reasonable physical therapy solutions for users.

ABSTRACT. Electrocardiography (ECG) is a standard non-invasive technique for diagnosing and researching human hearts. It records the cardiac electrical waveform over a while. Analyzing the resulting waveforms of the recorded electrical activity of the heart makes it possible to record and diagnose disease. The performance of ECG monitors can be affected by many factors, such as electromagnetic noise, power fluctuations, lack of circuit grounding, measurement cables contact, electrode attachment, and circuit failures. To check if the ECG device is working correctly, use an electrocardiogram simulator to simulate the ECG signal. An electrocardiogram simulator is a signal generator in the form of an electrocardiogram-like signal or a recorded electrocardiogram signal. This ECG simulator can be made based on microcontrollers and analog circuits. The advantages of this simulation study are the electrocardiogram signal is displayed as the original electrocardiogram record and has the appropriate ECG signal database. This ECG simulator also has the advantage of providing convenience for studying digital signal processing applications for electrocardiogram signals. This electrocardiogram simulator is designed with 3 essential leads: Right Arm (RA), Left Arm (LA), and Right Leg (RL) with 2 essential signals 60 and 120 bpm.

ABSTRACT. Nowadays, the number of patients with diabetes is increasing rapidly, which is one of the significant challenges facing the health field in the 21st century. Diabetes causes dangerous complications that can be life-threatening. such as stroke, heart attack, heart failure, kidney failure, blindness, and amputation. Continuous blood glucose monitoring is essential to prevent dangerous complications caused by diabetes. The most popular method of measuring blood glucose today is the finger prick technique to draw blood, it has high accuracy. However, this invasive and minimally invasive technique will cause pain, discomfort, and costly consumables each time. Among many other advanced methods, non-invasive blood glucose monitoring is still of particular interest and high demand because of its reliable potential, reasonable sensitivity, convenience, and painlessness. This paper investigates the feasibility of a non-invasive blood glucose monitoring system using light wavelengths of 660 nm and 940 nm. The results of building a regression line for the system to obtain the coefficient R2 is 0,7001 with 660 nm wavelength and R2 for groups of subjects: from 18-20 years old is 0.7358; from 21-24 years old is 0.7253; from 38-45 years old is 0.6431. This preliminary result may develop an optical-based non-invasive blood glucose monitoring device.

ABSTRACT. It is difficult to control the SARS-CoV-2 virus with many complicated strains with a fast-spreading speed. In Vietnam, the number of new infections gradually shows signs of increasing, potentially posing many future disease outbreak risks. The SIR model is a model that provides a practical approach to current and future epidemics; the SIR model is a classical, simple model of community infection. The model can add or change relevant components in the community, such as mortality, immigration or birth rates, resilience, and immunity. In this paper, we focus on COVID-19 data from Vietnam and model it using the SIR epidemiological model to analyze the spread of the disease and forecast the future disease situation. The results include an assessment of the fit or not of the model through the prediction over the periods.

ABSTRACT. Electrical Impedance Tomography (EIT) is a technology that uses recorded voltage data to reconstruct the distribution of electrical conductivity in a turbid medium and to illustrate the structures and abnormalities within that medium. The advantages of this imaging technology include non-ionization, non-invasive, impact and continuous monitoring, optimum design, and lower production costs as compared to current techniques such as Magnetic Resonance Imaging (MRI), Computed Tomography Scan (CT- Scan), and Ultrasonic... EIT has shown useful in a variety of medical domains, including identifying pneumothorax, assessing pulmonary edema, and evaluating ventilation distribution between different breathing modes. The EIT is also being studied for application for imaging reconstruction used to obtain images for medical imaging, geological exploration, industrial application and environmental sciences. In this research, a system of 16 electrodes is manufactured for simulate biological tissue using ground pork to simulate the internal environment of the human body. The confirmed experiments are carried out using a phantom while the frequencies between 10kHz to 100 kHz are changed. An Arduino and a PC are used to collect and process the measured data. Electrical Impedance Tomography and Diffusion-based Optical Tomography (EIDORS) software is used to recreate the cross-sectional image. The image reproduced at 100 kHz gives high accuracy to the reconstructed subject.

ABSTRACT. Significant losses of fresh horticultural crops occur during postharvest storage due to accelerated senescence and disease. Cooling and chemical preservation procedures are the typical postharvest techniques after harvest. Many researchers have lately used light-emitting diode (LED) therapy for postharvest storage of fruits and vegetables. Tomatoes are known as a superfood because they contain many compounds beneficial to human health. Tomato fruit contains a high proportion of lycopene, which increases as the fruit ripens to the breaker stage. LED systems have evolved as a clean and effective artificial lighting solution for use in horticulture. This research aimed to evaluate the influence of LEDs on postharvest and quality metrics. The impact on quality criteria varied greatly depending on the tomato fruit variety. Studies were conducted on timelines of LED light exposure per day throughout the postharvest fruit stage, which boosted commercial and organoleptic indices and lycopene concentrations. Overall, the results of this study indicated that postharvest exposure of tomato fruits to LED light causes lycopene synthesis, with a concentration of lycopene 41% greater than when subjected to light, dark, and 24% higher than when exposed to other LED lighting settings.

ABSTRACT. Analysis of the main factors causing instability in an internal combustion engine is a fundamental problem in operation research and engine design. The inhomogeneity between work cycles is the cause of the fluctuated power as well as other working parameters of the engine. It is expressed through the amount of fuel supplied to the cycle and the quality of the combustion process. The problem is to find a way to reduce the instability. The creation of devices for instability control based on nonlinear dynamic method is a new direction in studying the essence of inhomogeneity between work cycles. This paper presents experimental results on the instability of the combustion process in an internal combustion engine through the control method of fuel supply time. Studying the orderly structure of the resulting time-series pressure graph will further explain the essence of the inhomogeneity. Based on the results of the investigation of the pressure turbulence in the engine cylinders as well as the inhomogeneity between work cycles determined entirely by random processes, it will be possible to generate a different form of pressure graph using a suitable fuel injection timing device. The selection of signal interval control for injectors is studied and presented in this paper that is the basis for further studies to improve the efficiency of internal combustion engine in each operation mode.