On stationary Navier-Stokes equations in the upper-half plane

We study the incompressible stationary Navier-Stokes equations in the upper-half plane with homogeneous Dirichlet boundary condition and non-zero external forcing terms. Existence of weak solutions is proved under a suitable condition on the external forces. Weak-strong uniqueness criteria based on various growth conditions at the infinity of weak solutions are also given. This is done by employing an energy estimate and a Hardy's inequality. Several estimates of stream functions are carried out and two density lemmas with suitable weights for the homogeneous Sobolev space on 2 dimensional space are proved.Comment: 25 pages. No figure

Thermal effect on magnetoexciton energy spectra in monolayer transition metal dichalcogenides

It is widely comprehended that temperature may cause phonon-exciton scattering, enhancing the energy level's linewidth and leading to some spectrum shifts. However, in the present paper, we suggest a different mechanism that allows the thermal motion of the exciton's center of mass (c.m.) to affect the magnetoexciton energies in monolayer dichalcogenides (TMDCs). By the nontrivial but precise separation of the c.m. motion from an exciton in a monolayer TMDC with a magnetic field, we obtain an equation for the relative motion containing a motional Stark term proportional to the c.m. pseudomomentum, related to the temperature of the exciton gas but neglected in the previous studies. Solving the Schr\"odinger equation without omitting the motional Stark potential at room temperature shows approximately a few meV thermal-magnetic shifts in the exciton energies, significant enough for experimental detection. Moreover, this thermal effect causes a change in exciton radius and diamagnetic coefficient and enhances the exciton lifetime as a consequence. Surprisingly, the thermoinduced motional Stark potential breaks the system's SO(2) symmetry, conducting new peaks in the exciton absorption spectra at room temperature besides those of the $s$ states. This mechanism could be extended for other magnetoquasiparticles such as trions and biexcitons.Comment: 8 pages, 4 figures, 3 tables for main manuscript; 20 pages, 6 figures, 6 tables for supplementary. Published on Physical Review

Performance analysis for three cases of outage probability in one-way DF full-duplex relaying network with presence of direct link

In this paper, the one-way decode-and-forward (DF) full-duplex relaying network system with presence of direct link is investigated. In the analysis section, we derived the exact, lower, and upper bound for outage probability (OP) with maximal ratio combining (MRC) at the receiver. Furthermore, the system performance's analytical expressions are verified by using the Monte Carlo simulation. In addition, we investigated the effect of the main parameters on the OP of the proposed system. Finally, we can sate that the simulation curves overlap the analytical curves to convince the analysis section. This research can provide a novel recommendation for the communication network

Lower and upper bound form of outage probability in one-way AF full-duplex relaying network under impact of direct link

This paper proposed and investigated the one-way amplify-and-forward (AF) full-duplex relaying network under impact of direct link. For the system performance analysis, the exact and lower and upper bound form of the system outage probability (OP) are investigated and derived. In this system model, authors assume that the E uses the MRC (maximal ratio combining) technique. Finally, we can see that the analytical and the simulation values overlap to verify the analytical section using the Monte Carlo simulation. Also, we investigate the influence of the system primary parameters on the proposed system OP

Equality in Online Education during COVID-19: Challenging the Educational Needs of Ethnic Minority Students in Vietnam

[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities.[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities.[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities.[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities

Current medical product development for diagnosis, surgical planning and treatment in the areas of Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery in Vietnam

With the population of 86 million and good GDP growth in recent decades, the medical market in Vietnam is growing fast. However, most of the medical technology products are imported, and the number of locally manufactured ones is limited and they do not have the high competition capability in term of quality, quantity and types. In this paper, the current product development in Vietnam for diagnosis, surgical planning and treatment in the areas of Rehabilitation, Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery is presented. A roadmap for medical technology development in Vietnam is propose

Potential Usage of Rice Husk Ash-Cement Based Soil in Subbase and Base Courses in Road Construction

This paper presents an experimental study of rice husk ash-cement-based soil for layers in roadway construction. Rice husk ash (RHA) used in this study is a by-product of rice milling. In this work, twelve proportion mixes were used in this work with varying quantities of RHA (0-30%) and Portland cement blended amounts of 4, 6, 8%. The specimens were prepared by the Proctor mould method, conditioned at room temperature, and tested in soaked and unsoaked conditions. Specified curing periods of 7, 14, 28 days were applied for all types of specimens. Some engineering tests were carried out such as proctor compaction, unconfined compressive strength, splitting tensile strength, and the stiffness of stabilized soil. Test results indicated a general decrease in the maximum dry density (MDD) and increased optimum moisture content (OMC) with an increase in RHA content. Adding cement and RHA significantly improved the geotechnical properties of stabilized soils, including compressive strength, splitting tensile strength, elastic modulus. In addition, the combination of 80% soil and 20% RHA and 6% cement can be used as the optimum proportion which satisfied the grade 3 of soils stabilized with inorganic adhesive substances, chemical agents, or reinforced soil for road construction, as indicated in the current Vietnamese standard

Potential Usage of Rice Husk Ash-Cement Based Soil in Subbase and Base Courses in Road Construction

This paper presents an experimental study of rice husk ash-cement-based soil for layers in roadway construction. Rice husk ash (RHA) used in this study is a by-product of rice milling. In this work, twelve proportion mixes were used in this work with varying quantities of RHA (0-30%) and Portland cement blended amounts of 4, 6, 8%. The specimens were prepared by the Proctor mould method, conditioned at room temperature, and tested in soaked and unsoaked conditions. Specified curing periods of 7, 14, 28 days were applied for all types of specimens. Some engineering tests were carried out such as proctor compaction, unconfined compressive strength, splitting tensile strength, and the stiffness of stabilized soil. Test results indicated a general decrease in the maximum dry density (MDD) and increased optimum moisture content (OMC) with an increase in RHA content. Adding cement and RHA significantly improved the geotechnical properties of stabilized soils, including compressive strength, splitting tensile strength, elastic modulus. In addition, the combination of 80% soil and 20% RHA and 6% cement can be used as the optimum proportion which satisfied the grade 3 of soils stabilized with inorganic adhesive substances, chemical agents, or reinforced soil for road construction, as indicated in the current Vietnamese standard

ICT Integration in Developing Competence for Pre- Service Mathematics Teachers A Case Study from Six Universities in Vietnam

Competence structure that pre-service teachers need to develop to become a future teacher has been defined since the 1930s. For pre-service mathematics teachers, their competence has its own characteristics. ICT integration in developing competence for pre-service mathematics teachers has been been proved to be effective in many previous studies. In Vietnam, the Ministry of Education and Training (MOET) has recommended the use of ICT to enhance teaching-learning activities in schools and universities, therefore, there have been many studies on ICT intergration at different educational levels. However, there are only a few studies on the use ICT integration in developing competence for pre-service mathematics teachers. This paper presents results from a research on the feasibility of ICT integration in developing competence of Vietnamese pre-service mathematics teachers. The research was conducted by surveying on a randomly selected of 297 pre-service mathematics teachers and 40 mathematics lecturers in six universities which provide mathematics training programs. Results show that despite of the availability of technologies, ICT integration in training pre-service teachers is still limited. In addition, ICT integration in teaching activities of mathematics teachers is not really effective because the levels of their ICT skills are very different. Pre-service mathematics teachers have the ability to use ICT equipment, and good accessibility to learning systems, but their use of the learning management systems (LMS) is limited. This study can be a reference for future studies to test the effective of ICT integration in training pre-service teachers when designing activities to develop feasibly and effectively their competence