ISAS 2022:Papers with Abstracts

Abstract. This paper presents a static analysis of Sandwich Functionally Graded Material (FGM) beams structure under 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. Electrical Impedance Tomography (EIT) is a technology that uses recorded voltage data to reconstruct thedistribution 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. TheEIT 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. The patient experiences trouble walking and surviving as a result of tibia fractures or tibial osteoporosis. The tibia, a crucial bone in the lower extremities that requires the longest recovery time, as well as the relatively low level of activity in the legs, are both factors. In the patient's day-to-day existence, this has a substantial effect. Regenerating tissue, reducing pain, and reducing inflammation are all effects of low-level laser light. In this work, the effects of lasers of four different wavelengths—633 nm, 780 nm, 800 nm, and 940 nm—were examined using the Monte Carlo approach. We put the curve fitting technique into practice using the parameters we learned from the outcomes of the many Monte Carlo simulations. With an RSME of 2.62% and 1.32%, respectively, the findings demonstrated the link between energy and beam radius with regard to depth. We anticipate that the study will provide a quick analysis of how laser beams affect different regions in order to improve treatment settings.

Abstract. Functionally graded materials (FGMs) are complicated composites created using the concept of continuous variation of material property 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 those of metal, such as mechanical strength and rigidity. They are common in engineering practice, so static analysis and dynamic analysis for FGM plate structures are necessary. The radial point interpolation method (RPIM) meshless method has been used based on the point interpolation method (PIM) by including the radial basis function (RPF) in the interpolation formulation and has shown good performance in computational engineering. One of the advantages of this method is that it satisfies the Kronecker’s delta function, which overcomes the limitations of critical boundary conditions for the traditional meshless method. Furthermore, RPIM shape function satisfies the high-order continuity constraint, which the low-order finite element methods (FEM) method does not. This paper presents a meshless approach for the static and dynamic analysis of FGM plates whose 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 SOMSOL program to confirm the accuracy of the proposed method.

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. 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. 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. The large displacement analysis of microbeams and microframes is presented in this paper via a shear deformable corotational beam element. In order to account for the small size effect, the modified couple stress theory (MCST) is employed in conjunction with Timoshenko beam theory in deriving the internal force vector and tangent stiffness matrix of the beam element. Hierarchical functions are used to interpolate the local displacements and rotation. Newton-Raphson iterative procedure is adopted in combination with the arc-length method 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 behavior of the microstructure. The obtained result reveals that the size effect plays an important role on the large deflection response, and the displacements of the structure are overestimated by ignoring the size effect. A parametric study is carried out to highlight the influence of the material length scale parameter on the large displacement behavior of the microbeams and microframes.

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 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 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. 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 (multi- spectral 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. 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 diseases 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 is 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. 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. 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 a low-level laser therapy device, that could be used clinically for treating the degenerative spine.

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 a specific algorithm 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 and chemometrics combined 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. 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. 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. 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.

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 irradiations 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. 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.