WEAK AND STRONG CONVERGENCE OF SUBGRADIENT EXTRAGRADIENT METHODS FOR PSEUDOMONOTONE EQUILIBRIUM PROBLEMS

Hieu, Dang Van Korean Mathematical Society 2016 대한수학회논문집 Vol.31 No.4

In this paper, we introduce three subgradient extragradient algorithms for solving pseudomonotone equilibrium problems. The paper originates from the subgradient extragradient algorithm for variational inequalities and the extragradient method for pseudomonotone equilibrium problems in which we have to solve two optimization programs onto feasible set. The main idea of the proposed algorithms is that at every iterative step, we have replaced the second optimization program by that one on a specific half-space which can be performed more easily. The weakly and strongly convergent theorems are established under widely used assumptions for bifunctions.

Nonlinear vibration and stability of FG nanotubes conveying fluid via nonlocal strain gradient theory

Van-Hieu Dang,Hamid M. Sedighi,Do Quang Chan,Ömer Civalek,Ahmed E. Abouelregal 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.1

In this work, a model of a functionally graded (FG) nanotube conveying fluid embedded in an elastic medium is developed based on the nonlocal strain gradient theory (NSGT) in conjunction with Euler-Bernoulli beam theory (EBT). The main objective of this research is to investigate the nonlinear vibration and stability analysis of fluid-conveying nanotubes. The governing equations of motion are derived by means of Hamiltonian principle. The analytical expressions of nonlinear frequencies and critical flow velocities for two different types of boundary conditions including pinned-pinned (P-P) and clamped-clamped (C-C) conditions are obtained by employing Galerkin method as well as Hamiltonian Approach (HA). Comparison of the obtained results with the published works show the acceptable accuracy of the current solutions. The effects of the power-law index, the nonlocal and material length scale parameters and the elastic medium on the stability and nonlinear responses of FG nanotubes are thoroughly investigated and discussed.

A PARALLEL HYBRID METHOD FOR EQUILIBRIUM PROBLEMS, VARIATIONAL INEQUALITIES AND NONEXPANSIVE MAPPINGS IN HILBERT SPACE

Dang Van Hieu 대한수학회 2015 대한수학회지 Vol.52 No.2

In this paper, a novel parallel hybrid iterative method is pro- posed for finding a common element of the set of solutions of a system of equilibrium problems, the set of solutions of variational inequalities for inverse strongly monotone mappings and the set of fixed points of a finite family of nonexpansive mappings in Hilbert space. Strong con- vergence theorem is proved for the sequence generated by the scheme. Finally, a parallel iterative algorithm for two finite families of variational inequalities and nonexpansive mappings is established.

A PARALLEL HYBRID METHOD FOR EQUILIBRIUM PROBLEMS, VARIATIONAL INEQUALITIES AND NONEXPANSIVE MAPPINGS IN HILBERT SPACE

Hieu, Dang Van Korean Mathematical Society 2015 대한수학회지 Vol.52 No.2

In this paper, a novel parallel hybrid iterative method is proposed for finding a common element of the set of solutions of a system of equilibrium problems, the set of solutions of variational inequalities for inverse strongly monotone mappings and the set of fixed points of a finite family of nonexpansive mappings in Hilbert space. Strong convergence theorem is proved for the sequence generated by the scheme. Finally, a parallel iterative algorithm for two finite families of variational inequalities and nonexpansive mappings is established.

Facile synthesis of SnO2eZnO coreeshell nanowires for enhanced ethanol-sensing performance

Dang Thi Thanh Le,Do Dang Trung,Nguyen Duc Chinh,Bui Thi Thanh Binh,Hoang Si Hong,Nguyen Van Duya,Nguyen Duc Hoa,Nguyen Van Hieu 한국물리학회 2013 Current Applied Physics Vol.13 No.8

The design of coreeshell heteronanostructures is powerful tool to control both the gas selectivity and the sensitivity due to their hybrid properties. In this work, the SnO2eZnO coreeshell nanowires (NWs) were fabricated via two-step process comprising the thermal evaporation of the single crystalline SnO2 NWs core and the spray-coating of the grainy polycrystalline ZnO shell for enhanced ethanol sensing performance. The as-obtained products were investigated by X-ray diffraction, scanning electron microscopy,and photoluminescence. The ethanol gas-sensing properties of pristine SnO2 and ZnOeSnO2 core eshell NW sensors were studied and compared. The gas response to 500 ppm ethanol of the coreeshell NW sensor increased to 33.84, which was 12.5-fold higher than that of the pristine SnO2 NW sensor. The selectivity of the coreeshell NW sensor also improved. The response to 100 ppm ethanol was about 14.1,whereas the response to 100 ppm liquefied petroleum gas, NH3, H2, and CO was smaller, and ranged from 2.5 to 5.3. This indicates that the coreeshell heterostructures have great potential for use as gas sensing materials.

MODIFIED SUBGRADIENT EXTRAGRADIENT ALGORITHM FOR PSEUDOMONOTONE EQUILIBRIUM PROBLEMS

Dang, Van Hieu Korean Mathematical Society 2018 대한수학회보 Vol.55 No.5

The paper introduces a modified subgradient extragradient method for solving equilibrium problems involving pseudomonotone and Lipschitz-type bifunctions in Hilbert spaces. Theorem of weak convergence is established under suitable conditions. Several experiments are implemented to illustrate the numerical behavior of the new algorithm and compare it with a well known extragradient method.

Outcomes of laparoscopic choledochotomy using cholangioscopy via percutaneous-choledochal tube for the treatment of hepatolithiasis and choledocholithiasis: A preliminary Vietnamese study

Loi Van Le,Quang Van Vu,Thanh Van Le,Hieu Trung Le,Khue Kim Dang,Tuan Ngoc Vu,Anh Hoang Ngoc Nguyen,Thang Manh Tran 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1

Backgrounds/Aims: Hepatolithiasis and choledocholithiasis are frequent pathologies and unfortunately, with the current treatment strategies, the recurrence incidence is still high. This study aimed to assess the outcomes of laparoscopic choledochotomy using cholangioscopy via the percutaneous-choledochal tube for the treatment of hepatolithiasis and choledocholithiasis in Vietnamese patients. Methods: A cross-sectional study of patients with hepatolithiasis and/or choledocholithiasis who underwent laparoscopic choledochotomy using intraoperative cholangioscopy via percutaneous-choledochal tube at the Department of Hepatopancreatobiliary Surgery, 108 Military Central Hospital, from June 2017 to March 2020. Results: A total of 84 patients were analyzed. Most patients were females (56.0%) with a median age of 55.56 years. Among them, 41.8% of patients had previous abdominal operations, with 33.4% having choledochotomy. All patients underwent successful laparoscopic common bile duct exploration followed by T-tube drainage without needing to convert to open surgery. Most patients (64.3%) had both intrahepatic and extrahepatic stones. The rate of stones ≥ 10 mm in diameter was 64.3%. Biliary strictures were observed in 19.1% of patients during cholangioscopy. Complete removal of stones was achieved in 54.8% of patients. Intraoperative complications were encountered in two patients, but there was no need to change the strategy. The mean operating time was 121.85 ± 30.47 minutes. The early postoperative complication rate was 9.6%, and all patients were managed conservatively. The residual stones were removed through the T-tube tract by subsequent choledochoscopy in 34/38 patients, so the total success rate was 95.2%. Conclusions: Laparoscopic choledochotomy combined with cholangioscopy through the percutaneous-choledochal tube is a safe and effective strategy for hepatolithiasis and/or choledocholithiasis, even in patients with a previous choledochotomy.

Influence of Credit on the Income of Households Borrowing from Banks: Evidence from Vietnam Bank for Agriculture and Rural Development, Kien Giang Province

Quang Vang DANG(Quang Vang DANG ),Viet Thanh Truc TRAN(Viet Thanh Truc TRAN ),Hieu PHAM(Hieu PHAM ),Van Nam MAI(Van Nam MAI ),Quoc Duy VUONG(Quoc Duy VUONG ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.2

This paper investigates the determinants of credit accessibility and the effect of credit on the income of farm households borrowing from Vietnam Bank for Agriculture and Rural Development, Giong Rieng District Branch, Kien Giang Province. Based on the primary data of 200 farming households who are the customer of the bank, the study applied the Probit regression model to examine determinant factors of credit accessibility of farm households and employed the Propensity score matching method to investigate the impact of credit on households’ income. The findings of the Probit regression shown that three independent variables that significantly influence the access to credit of households are household size, income source, and farm size. Besides that, the Propensity score matching method results showed a difference of 23.799 million VND/year between the income of borrowing households and that of non-borrowing households at the significance level of 1%. The difference in the imcome from the interval and central matching methods are VND 24.700 million VND/year and VND 24.633 million VND/year, respectively. Given empirical findings suggetsted that several recommendations to increase the credit accessibility of farm households, thereby creating favorable conditions for improving their income.

Orodispersible film incorporating nanoparticulate loratadine for an enhanced oral bioavailability

Van Nguyen Khanh,Dang Thu Kim,Vu Linh Thi Dieu,Ha Nhan Thi,Truong Hieu Duy,Tran Tuan Hiep 한국약제학회 2023 Journal of Pharmaceutical Investigation Vol.53 No.3

Purpose Loratadine (LOR), a commonly prescribed antihistamine, has low water solubility but high permeability. In this study, an orodispersible film incorporating the nanoparticulate loratadine was prepared to enhance the oral bioavailability of a poorly water-soluble drug. Methods Nanoparticulate loratadine was formulated using the antisolvent precipitation method and optimized by a singlefactor design based on the particle size and polydispersity index. The optimal formulation was spray-dried and characterized by powder X-ray diffraction and differential scanning calorimetry. Nanoparticulate loratadine was loaded into an orodispersible film using a solvent casting method. Results In the dissolution tests, the nanoparticulate loratadine-loaded orodispersible film exhibited a 6.5-fold higher dissolution rate than the pure loratadine-loaded film and a similar dissolution rate compared to the commercialized orodispersible tablet, Loratadine SPM. In pharmacokinetic studies conducted on rats, the maximum concentration (Cmax) and area under the curve of the plasma concentration–time profile from 0 to 24 h (AUC 0-24 h) of the nanoparticulate loratadine-loaded orodispersible film significantly increased 1.8-fold and 5.8-fold, respectively. The elimination half-life (t1//2) increased 5.1-fold compared to the loratadine-loaded counterpart. Conclusion These results suggest the potential of orodispersible films to improve the oral bioavailability of poorly watersoluble drugs and promote compliance in pediatric and geriatric patients.

The study of shape of electrodes and I-V characteristics for Ultraviolet LED

Trung, Nguyen Huu,Dang, Vu The,Hieu, Nguyen Van Institute of Korean Electrical and Electronics Eng 2013 전기전자학회논문지 Vol.17 No.3

About functional parameters of a LED/UVLED (Light Emitting Diode/Ultra Violet LED), one of the most important parameters is the I-V characteristic. By researching factors affect to the I-V characteristic of uvled, we found that beside of the structure of the device itself, there is the influence of the electrode materials, electrode shapes, the process of wiring and packaging. In this work, we want to improve the performance of UVLED to find out the optimal mask design principles. The study is based on theoretical mathematical models, as well as the use of simulation software tool Comsol. From all results obtained, the team has improved mask design to manufacture electrodes for GaN-based UVLED. Electrode masks are designed by three softwares, which are Intellisuite, Klayout and AutoCad. Intellisuite masks would be used in fabrication simulation while Klayout and AutoCad are used to fabricate electrodes in experiments. As well as, we silmulated the structure of an uvled 355nm emission wavelength by TCAD software, in order to compare with uvled sample that has the same emission wavelength.