94 research outputs found
Theory and numerical modeling of photonic resonances: Quasinormal Modal Expansion -- Applications in Electromagnetics
The idea of the modal expansion in electromagnetics is derived from the
research on electromagnetic resonators, which play an essential role in
developments in nanophotonics. All of the electromagnetic resonators share a
common property: they possess a discrete set of special frequencies that show
up as peaks in scattering spectra and are called resonant modes. These resonant
modes are soon recognized to dictate the interaction between electromagnetic
resonators and light. This leads to a hypothesis that the optical response of
resonators is the synthesis of the excitation of each physical-resonance-state
in the system: Under the excitation of external pulses, these resonant modes
are initially loaded, then release their energy which contributes to the total
optical responses of the resonators. These resonant modes with complex
frequencies are known in the literature as the Quasi-Normal Mode (QNM).
Mathematically, these QNMs correspond to solutions of the eigenvalue problem of
source-free Maxwell's equations. In the case where the optical structure of
resonators is unbounded and the media are dispersive (and possibly anisotropic
and non-reciprocal) this requires solving non-linear (in frequency) and
non-Hermitian eigenvalue problems. Thus, the whole problem boils down to the
study of the spectral theory for electromagnetic Maxwell operators. As a
result, modal expansion formalisms have recently received a lot of attention in
photonics because of their capabilities to model the physical properties in the
natural resonance-state basis of the considered system, leading to a
transparent interpretation of the numerical results. This manuscript is
intended to extend the study of QNM expansion formalism, in particular, and
nonlinear spectral theory, in general. At the same time, several numerical
modelings are provided as examples for the application of modal expansion in
computations.Comment: PhD thesi
EFL TEACHERS’ PERCEPTIONS AND THEIR REPORTED PRACTICES OF ENACTING THE COMMUNICATION AND CULTURE SECTION IN THE NEW ENGLISH TEXTBOOK
The development of globalization and integration requires a modern workforce with 21st-century skills, especially intercultural communicative competence (ICC). Thanks to the National Foreign Language 2020 project, the new English textbooks were introduced to Vietnamese students with the hope prepare them for ICC. Research on how EFL teachers explored the new teaching materials has been made, but previous findings show limitations on EFL teachers’ practices in the communication and culture section. Hence, this descriptive research was conducted to investigate EFL teachers’ perceptions and their reported practices of enacting this section. A mixed-method approach was employed to collect quantitative and qualitative data. Seventy-two EFL teachers in the Mekong Delta responded to the questionnaire and seven of them joined the semi-structured interviews. Results revealed various EFL teachers’ perceptions and high levels of agreement on their practices of four dimensions of ICC. The study also suggested further research should look into students’ perspectives. Article visualizations
QUANTUM TELEPORTATION OF ENTANGLED STATES VIA GENERALIZED PHOTON-ADDED PAIR COHERENT STATE
In this paper, we study the quantum teleportation of an unknown atomic state based on the two-photon Jaynes-Cummings model, consisting of an effective two-level atom with a two-mode field in the generalized photon-added pair coherent state (GPAPCS). By applying the detecting method, we use a scheme that includes two two-level atoms and a cavity field to teleport the unknown atomic state from a sender to a receiver. The results show that the number of photons added to the field and the intensity of the initial field influence the average fidelity and success probability of the teleportation process. The time-evolution dependence of the average fidelity is also considered and compared for the field in the pair coherent state and in the GPAPCS
FEMs on composite meshes for plasma equilibrium simulations in tokamaks
International audienceWe rely on a combination of different finite element methods on composite meshes, for the simulation of axisymmetric plasma equilibria in tokamaks.One mesh with Cartesian quadrilaterals covers the vacuum chamber and one mesh with triangles discretizes the region outside the chamber. The two meshes overlap in a narrow region around the chamber. This approach gives the flexibility to achieve easily and at low cost higher order regularity for the approximation of the flux function in the area that is covered by the plasma, while preserving accurate meshing of the geometric details in the exterior. The continuity of the numerical solution across the boundary of each subdomain is enforced by a new mortar-like projection
Sensing the position of a single scatterer in opaque media using Mutual Extinction and Transparency
ANALYSIS OF THE POPULARITY OF VOCABULARY USED WHEN PERFORMING SPEAKING ACTIVITIES IN THE CLASS OF FIRST-YEAR ENGLISH LANGUAGE STUDENTS IN THE DIRECTION OF DISCOURSE ANALYSIS
Vocabulary learning is extremely important when learning a foreign language. Fluency in a language depends on vocabulary and its use in specific situations. Speaking well is using vocabulary flexibly and speaking fluently. Researching the popularity of vocabulary is analyzing the prevalence of vocabulary used by linguistics students in communication from discourse analysis. This is a topic the research team is working on. This project will help the researchers learn about common vocabulary that students often use to communicate outside or in the classroom. Thereby understanding whether the vocabulary that students use is diverse, rich, and for the right purpose or not. This study will help students have a more comprehensive view of the ways to use words in communication. In addition, it also helps students improve their communication vocabulary, helps in exams and can be useful for later work. In this study, the research team will investigate the students' ability to use spoken vocabulary, i.e., frequency and extent of vocabulary usage. Article visualizations
Delving into Ipsilateral Mammogram Assessment under Multi-View Network
In many recent years, multi-view mammogram analysis has been focused widely
on AI-based cancer assessment. In this work, we aim to explore diverse fusion
strategies (average and concatenate) and examine the model's learning behavior
with varying individuals and fusion pathways, involving Coarse Layer and Fine
Layer. The Ipsilateral Multi-View Network, comprising five fusion types (Pre,
Early, Middle, Last, and Post Fusion) in ResNet-18, is employed. Notably, the
Middle Fusion emerges as the most balanced and effective approach, enhancing
deep-learning models' generalization performance by +2.06% (concatenate) and
+5.29% (average) in VinDr-Mammo dataset and +2.03% (concatenate) and +3%
(average) in CMMD dataset on macro F1-Score. The paper emphasizes the crucial
role of layer assignment in multi-view network extraction with various
strategies
Probing the Position Resolved Energy Density Inside Photonic Scattering Slabs with Strong Absorption and Anisotropy
Understanding the transport of light in photonic scattering media is crucial for many application areas, such as atmospheric and climate sciences [1,2], oceanography [3], biophysics [4,5], powder technology [6], and solid-state lighting [7,8]. In photonic scattering media, such as paint, foam, and tissue, the refractive index varies spatially causing incident waves to be scattered and absorbed [9,10]. While Monte Carlo simulations accurately describe light transport in complex media, they are extremely slow and require high computation power. Fast and accurate analytical methods are needed especially for industrial applications. The P1 approximation to the radiative transfer equation (RTE) is a commonly utilized analytical method [11]. However, it is known that P1 fails for samples with both predominant forward scattering and strong absorption, resulting in unphysical negative energy densities. The accuracy of the analytical PN approximation depends on the order N, the scattering properties of the sample, like albedo, anisotropy, optical thickness, and refractive index contrast of the sample and the surrounding medium [12].</p
Association between ACE I/D genetic polymorphism and the severity of coronary artery disease in Vietnamese patients with acute myocardial infarction
BackgroundThe severity of coronary artery disease is a prognostic factor for major adverse cardiovascular events in patients diagnosed with acute myocardial infarction. ACE I/D polymorphism is one of the genetic factors that may affect the severity of coronary artery disease. This study aimed to investigate the association between ACE I/D genotypes and the severity of coronary artery disease in patients with acute myocardial infarction.Materials and methodsA single-center, prospective, observational study was conducted at the Department of Cardiology and Department of Interventional Cardiology, Cho Ray Hospital, Ho Chi Minh City, Vietnam from January 2020 to June 2021. All participants diagnosed with acute myocardial infarction underwent contrast-enhanced coronary angiography. The severity of coronary artery disease was determined by Gensini score. ACE I/D genotypes were identified in all subjects by using the polymerase chain reaction method.ResultsA total of 522 patients diagnosed with first acute myocardial infarction were recruited. The patients' median Gensini score was 34.3. The II, ID, and DD genotype rates of ACE I/D polymorphism were 48.9%, 36.4%, and 14.7%, respectively. After adjusting for confounding factors, multivariable linear regression analysis showed that the ACE DD genotype was independently associated with a higher Gensini score compared with the II or ID genotypes.ConclusionThe DD genotype of the ACE I/D polymorphism was associated with the severity of coronary artery disease in Vietnamese patients diagnosed with first acute myocardial infarction
Slip Resistance Test Apparatus of Synthetic Rubber Trackpad on Photovoltaic Surface
The increasing development of the solar energy industry in many countries has
led to a rising frequency of human and robot presence in this area. To ensure
occupational safety, various protective equipment, including rubber material,
is commonly used for slip resistance while moving on the surface of solar PV
panels. Therefore, the slip resistance test apparatus is built for testing the
slip resistance between the synthetic rubber trackpad and the photovoltaic
panel (PV) surface. Synthetic rubber is a man-made material, so it is difficult
to control the parameters of its mechanical and chemical properties absolutely.
Variations in wet/dry working conditions or Shore hardness are factors that
make slip computation more challenging. Therefore, an apparatus with the
principle of converting the reciprocating motion of the screw and the casters
into the rotation of the hinge is introduced to adjust the tilt angle of the
upper surface, detect and evaluate the slippage of the rubber trackpad by
sensors. Some parameters related to accuracy such as vibration and
theoretical-empirical assessment, are also mentioned. In addition to designing
a reliable apparatus, the article also succeeded in providing a safety standard
for synthetic rubber with Shore A30-A40 when moving on PV surfaces.Comment: 4 pages, 10 figures, The 20th International Conference on Ubiquitous
Robots (UR 2023
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