Luong Theu - Academia.edu (original) (raw)

Papers by Luong Theu

Sensors and actuators. A, Physical, Apr 1, 2024

Journal of physics. Conference series, Apr 1, 2024

Research Square (Research Square), Feb 29, 2024

The distorted Born iterative (DBI) method is considered to obtain images with high-contrast and r... more The distorted Born iterative (DBI) method is considered to obtain images with high-contrast and resolution. Besides satisfying the Born approximation condition, the frequency-hopping (FH) technique is necessary to gradually update the sound contrast from the first iteration and progress to the actual sound contrast of the imaged object in subsequent iterations. Inspired by the fact that the higher the frequency, the higher the resolution. Because low-frequency allows for low-resolution object imaging, hence for high-resolution imaging requirements, using low-frequency to possess a high-resolution image from the first iteration will be less efficient. For an effective reconstruction, the object's resolution at low frequencies should be small. And similarly, with high frequencies, the object resolution should be larger. Therefore, in this paper, the FH, and the resolution-turning (RT) technique are proposed to obtain object images with high-contrast and-resolution. The convergence speed in the initial iterations is rapidly achieved by utilizing low frequency in the frequency-turning technique and low image resolution in the resolution-turning technique. It is crucial to ensure accurate object reconstruction for subsequent iterations. The desired spatial resolution is attained by employing high frequency and large image resolution. The resolution-turning distorted Born iterative (RT-DBI) and frequency-hopping distorted Born iterative (FH-DBI) solutions are thoroughly investigated to exploit their best performance. This makes sense because if it is not good to choose the number of iterations for the frequency f1 in FH-DBI and for the resolution of N1×N1 in RT-DBI, then these solutions give even worse quality than traditional DBI. After that, the RT-FH-DBI integration was investigated in two sub-solutions. We found that the lower frequency f1 used both before and after the RT would get the best performance. Consequently, compared to the traditional DBI approaches, the normalized error and total runtime for the reconstruction process were dramatically decreased, at 83.6% and 18.6%, respectively. Besides fast and quality imaging, the proposed solution RT-FH-DBI is promised to produce high-contrast and high-resolution object images, aiming at object reconstruction at the biological tissue. The development of 3D imaging and experimental verification will be studied further. The field of clinical diagnostics has been strongly influenced by the advancements in biomedical imaging technology. The explosive growth of information technology and digital media has brought forth clever and advanced techniques for diagnosis and treatment 1. Wilhelm Roentgen discovered X-rays in 1885, which marked the birth of biomedical imaging technology. Over the past century, the development of advanced technologies, ranging from radiography to computed tomography (CT), positron emission tomography (PET), ultrasonography, single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), and more, has led to significant changes in the clinical medicine field. The effectiveness of non-invasive imaging methods has rapidly evolved alongside advancements in computer science. Biomedical imaging methods involve capturing images of animal or human body parts to gather data about tissues, structures, or specific characteristics of tissues, bones, and even physiological features by administering specialized substances into the body 2. Currently, there are various biomedical imaging methods as mentioned above, and the research direction of this study focuses on ultrasound imaging, as it is one of the most widely used and represents the gold standard in essential diagnostic examinations, such as obstetrics and cardiology. Imaging techniques utilizing sound waves have been extensively applied since the development of sonar technology in 1910. Among the most popular methods, using the principles of sonar, is B-mode imaging 3. This

Lecture notes in networks and systems, Dec 31, 2022

2023 Asia Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC)

Tạp chí Khoa học Tự nhiên, 2016

The European Physical Journal Plus

Journal of physics, Apr 1, 2023

Hue University Journal of Science: Natural Science, 2017

Viện vật lý-Viện Hàn lâm khoa học và Công nghệ Việt Nam Tóm tắt: Trong bài báo này, chúng tôi mô ... more Viện vật lý-Viện Hàn lâm khoa học và Công nghệ Việt Nam Tóm tắt: Trong bài báo này, chúng tôi mô tả sự phụ thuộc tính chất quang của hạt nano vàng bọc bằng bằng protein bovine serum albumin (BSA) theo nhiệt độ, sử dụng lý thuyết chuyển pha soliton. Hạt nano vàng có bán kính r khi bọc bằng lớp protein có bề dày là d làm cho bán kính hiệu dụng R của hạt nano vàng tăng lên. Khi chưa tính đến sự thay đổi nhiệt độ của môi trường thì bán kính hạt tăng lên không đáng kể. Bước sóng hấp thụ phụ thuộc tuyến tính vào bán kính hạt. Khi nhiệt độ môi trường bao quanh hệ phức hạt thay đổi thì bán kính hiệu dụng của hạt R phụ thuộc vào nhiệt độ, do bề dày của lớp protein thay đổi theo nhiệt độ. Tại nhiệt độ biến tính TC của protein, bán kính hiệu dụng của hạt tăng nhanh do protein BSA bất ngờ duỗi ra, dẫn đến sự dịch phổ đỏ của hệ phức hạt cầu. Theo mô hình này chúng tôi đã bước đầu xác định được dạng hàm phụ thuộc của bước sóng hấp thụ của hạt nano vàng bọc bằng protein BSA vào nhiệt độ là hàm tan và khi so sánh với thực nghiệm thấy có sự phù hợp khá tốt. Từ khóa: Tính chất quang; hạt nano vàng; BSA, chuyển pha; bán kính hiệu dụng

VNU Journal of Science: Education Research

In Vietnam general education curriculum 2018, a learning model called STEM education is being int... more In Vietnam general education curriculum 2018, a learning model called STEM education is being interested in and encouraged in teaching and learning. Choosing a STEM topic will engage students to explore knowledge. The topics which selected need to be linked to reality and have a direct impact on human life. In the era of industry 4.0, besides data science, machine learning, artificial intelligence, etc., the role of automation is indispensable. The previously developed STEM topics are quite diverse, including topics on physics, chemistry, biology, informatics, etc. However, STEM topics about automatic control field are rarely exploited to increase students' awareness of the role of automation in life in the era of technology revolution 4.0, and also enrich the topics of learning and experience in the contents of smart home, warning system, etc. in the general education program issued in 2018. In this paper, therefore, we propose a new STEM project in the field of smart models,...

Journal of Physics: Conference Series, 2017

The enhanced Forster resonance energy transfer is obtained in recent experiments. One of the most... more The enhanced Forster resonance energy transfer is obtained in recent experiments. One of the most important experimental facts is the observed strong enhancement of donor fluorescence with increasing concentration of metallic nanoparticle acceptors in the first stage. We propose three types of energy transfer mechanisms (Forster FRET, surface SET, and Coulomb CET) and predict simple relations for their dependencies on the concentration of metallic nano-particles. The competition of these mechanisms leads to the transfer intensity dependence on the concentration dependence of metallic nano-particles. Using these assumptions, we expect and argue about the compatibility between the experimental results.

IEEE Access

In pharmacokinetics, the clinical information collected from the patient is often much less than ... more In pharmacokinetics, the clinical information collected from the patient is often much less than the complexity of the patient's internal operations, hence the undetermined inverse problem has emerged as a challenge to solve it and find multiple possible point sets for considering the many possible implications of drug kinetics in the patient's body. This paper suggests two enhanced schemes for the early cluster Newton method (CNM) to concomitantly explore a great solutions number for the inverse parameter determination in pharmacokinetics. The first scheme is the application of Tikhonov regularization to deal with the overdetermined system for hyperplane fitting in the CNM, and the second is an effective iterative strategy by tuning perturbation-level for the CNM. As a result of Tikhonov's filtering operation, lower order singular values than the regularization parameter, that are to blame for the instability of the matrix equation, are efficiently eliminated. With perturbation-level tuning, following every iteration, as the point cluster (PoC) gets near the solution manifold (SoM), it is essential to lessen the level of perturbation in the patient's clinical measurement data and this is suited for a numerical stabilization. Numerical simulation scenarios of two schemes have revealed that these suggested schemes can lower the iterations number and computed time, and PoC move more steadily towards the solutions manifold. INDEX TERMS Tikhonov regularization, physiologically based pharmacokinetics, pharmacokinetics, cluster Newton method, inverse problem.

2022 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC)

AIP Advances

We study the band valley modification induced by isotropic strain in monolayer WSe2 using the non... more We study the band valley modification induced by isotropic strain in monolayer WSe2 using the non-local van der Waals density functionals theory including the spin–orbit coupling effect. The dominant contributions of orbitals to the band extrema, spin splitting, and exciton diversity in monolayer WSe2 are visually displayed. The vertical shift of the d and p partial orbitals of W and Se atoms, respectively, at band edges under strain results in a notable reduction of the bandgap. Under tensile strain, the deformations of the band valleys lead to an additional appearance of optical excitons and the disappearance of momentum excitons. Therefore, the experimental observations of the changes in the radiation spectra such as the redshift of A and B excitons, blueshift of C and D excitons, enhancement of intensity, localization, and symmetrization of the exciton resonances can be explained thoroughly. Under compression, the band valley modification may lead to an additional appearance of ...

Electronics

In ultrasound tomography, cross-sectional images represent the spatial distribution of the physic... more In ultrasound tomography, cross-sectional images represent the spatial distribution of the physical parameters of a target of interest, which can be obtained based on scattered ultrasound measurements. These measurements can be obtained from dense datasets collected at different transmitter and receiver locations, and using multiple frequencies. The Born approximation method, which provides a simple linear relationship between the objective function and the scattering field, has been adopted to resolve the inverse scattering problem. The distorted Born iterative method (DBIM), which utilizes the first-order Born approximation, is a productive diffraction tomography scheme. In this article, the range of interpolation applications is extended at the multilayer level, taking into account the advantages of integrating this multilayer level with multiple frequencies for the DBIM. Specifically, we consider: (a) a multi-resolution technique, i.e., a multi-step interpolation for the DBIM: M...