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Velocity equation for grenades while impacting on dry sand media

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Defence Technology（防务技术） 2024年第5期35卷 168-173页

作者： Martin Macko Xuan son Bui Kongsathit Phanthavong Duc Hung Pham Van Gion Do Van Minh Do Jiri Skala University of Defence BrnoCzech Republic le Quy Don Technical University Ha NoiViet Nam

This paper deals with the collision of sphere shape grenades with sand *** central issue of the article is the establishing of an empirical velocity equation of the grenade while impacting on sand that is used to solve motion equations of the mechanical mechanism inside the impact grenade *** paper focuses on impact velocities that are lower than 5 m s^(-1).An experiment was conducted to study the velocity of the grenade while impacting on dry sand.A high-speed camera video was used to capture the grenade *** grenade velocity in the impact process was generated from these video *** types of fitting curves are used to regress the velocity equation of the grenade while interacting with the sand media and the best-fitting model is *** result shows the regression curve has a high correlation with the experiment data for grenade velocities below 5 m s^(-1).The received regression equation is useful for analyzing the working ability of the inertial mechanism inside the impact grenade or analyzing and choosing the appropriate parameters of each part in the inertial mechanism to meet the required characteristics of the mechanism.

关键词： Dynamic response Impact velocity Impact grenade Low-velocity impact

Effects of low energy (160 keV) X-ray on microbial inactivation,sprouting inhibition and genetic variation in potato

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Food Bioscience 2022年第3期47卷 262-270页

作者： Nguyen An son Nguyen Thi Nguyet Ha Nguyen Thi Minh Sang le Doan Dinh Duc le Ngoc Trieu Faculty of Physic and Nuclear Engineering Da Lat UniversityViet Nam Dalat Vocational Training College Viet Nam Faculty of Biology Da Lat UniversityViet Nam

The effects of low energy X-ray irradiation on microbial inactivation,sprouting inhibition and genetic variation were *** was an inverse correlation between the exposure dose in range of 0 Gy–5000 Gy and the survival rate of *** dose of 1000 Gy seemed to be suitable for inactivation of microorganisms because the respective survival rate is relatively low (0.59%).Dose rate of 13.87 Gy/min was the most appropriate to inactivate the microorganisms,with the survival rate of 0.37%.Applying the irradiation dose of 1000 Gy and dose rate of 13.87 Gy/min,there was a significant sprouting inhibition of irradiated potatoes compared to the control for six months *** effect of irradiation dose (100–1200 Gy) and dose rate (8.63–19.62 Gy/min) on genetic variation of the irradiated samples was assessed by DNA fingerprints induced from using three molecular techniques including Random Amplified Polymorphic DNA (RAPD),Start Codon Targeted Polymorphism (SCoT) and CAAT box – derived polymorphism (CBDP).At the irradiation dose of 1000 Gy and dose rate of 13.87 Gy/min,the level of genetic variation was relatively low (4.85%).Thus,this treatment is a suitable condition of irradiation for potato treatment with the purpose of preservation.

关键词： Dose Dose rate Low energy X-ray Microbial inactivation Potato

Determination of the Pore Water Velocity Using a Salt Tracer Combined with Self-Potential Measurements

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Journal of Geoscience and Environment Protection 2023年第1期11卷 15-27页

作者： Huong Huynh Thi Thu son le Van Hieu Tran Trong Hai Lai viet Quang Nguyen Huu Luan Phan Thi Department of Tracer Techniques Center for Applications of Nuclear Technique in Industry Dalat Vietnam

The tracer technique is recommended as an effective tool in surveying abnormal seepage through lakes and dams. By injecting a tracer into a known upstream location and monitoring the appearance of the tracer in the downstream leak point, it is possible to determine the direction and the average water velocity of the preferential flow through the dam. The detailed result achieved depends on the number of samples and the sampling locations to analyze tracer concentration over time in the field. This study proposes to use noninvasive self-potential measurements to determine the location and time the salt tracer moves through the seepage zone. The connection between the potential signal according to the propagation of the NaCl salt tracer and the water velocity was demonstrated through an experiment on a sandbox model. Experimental results express a good agreement between the time to reach the maximum value of the potential variation and the salt concentration variation with the time that water comes to monitoring locations. The result indicates an ability to determine the pore water velocity of the seepage zone based on the recording of potential signals produced by a salt tracer movement. The salt tracer test using NaCl combined with self-potential measurements was then applied to survey a leaking earth dam in the Dong Nai river basin (vietnam).

关键词： Earthen Dams Tracer Technique leakage Interstitial Velocity

Iterative Method for Solving a Problem with Mixed Boundary Conditions for Biharmonic Equation

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Advances in Applied Mathematics and Mechanics 2009年第5期1卷 683-698页

作者： Dang Quang A le Tung son Institute of Information Technology 18 Hoang Quoc viet Cau giayHanoiVietnam Pedagogic College Thai Nguyen UniversityVietnam

The solution of boundary value problems(BVP)for fourth order differential equations by their reduction to BVP for second order equations,with the aim to use the available efficient algorithms for the latter ones,attracts attention from many *** this paper,using the technique developed by the authors in recent works we construct iterative method for a problem with complicated mixed boundary conditions for biharmonic equation which is originated from nanofluidic *** convergence rate of the method is proved and some numerical experiments are performed for testing its dependence on a parameter appearing in boundary conditions and on the position of the point where a transmission of boundary conditions occurs.

关键词： Iterative method biharmonic equation mixed boundary conditions

A stable CS-FEM for the static and seismic stability of a single square tunnel in the soil where the shear strength increases linearly with depth

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1253-1265页

作者： H.C.Nguyen L.Nguyen-son Department of Civil and Environmental Engineering Imperial College LondonLondonUK Department of Civil Engineering and Industrial Design University of LiverpoolLiverpoolUK Faculty of Civil Engineering Ho Chi Minh City University of Technology(HUTECH)Ho Chi Minh CityViet Nam

A numerical procedure using a stable cell-based smoothed finite element method(CS-FEM)is presented for estimation of stability of a square tunnel in the soil where the shear strength increases linearly with *** kinematically admissible displacement fields are approximated by uniform quadrilateral elements in conjunction with the strain smoothing technique,eliminating volumetric locking issues and the singularity associated with the MohreCoulomb ***,a rich set of simulations was performed to compute the static stability of a square tunnel with different geometries and soil *** presented results are in excellent agreement with the upper and lower bound solutions using the standard finite element method(FEM).The stability charts and tables are given for practical use in the tunnel design,along with a newly proposed formulation for predicting the undrained stability of a single square ***,the seismic stability number was computed using the present numerical *** results reveal that the seismic stability number reduces with an increasing value of the horizontal seismic acceleration(a_(h)),for both cases of the weightless soil and the soil with unit ***,the link between the static and seismic stability numbers is described using corrective factors that represent reductions in the tunnel stability due to seismic *** is shown from the numerical results that the corrective factor becomes larger as the unit weight of soil mass increases;however,the degree of the reduction in seismic stability number tends to reduce for the case of the homogeneous ***,this advanced numerical procedure is straightforward to extend to three-dimensional(3D)limit analysis and is readily applicable for the calculation of the stability of tunnels in highly anisotropic and heterogeneous soils which are often encountered in practice.

关键词： Tunnels Stability Limit analysis Cell-based smoothed finite element method (CS-FEM) Second-order cone programming(SOCP)

Evaluation of the Ability to Apply Near-Infrared Spectroscopy on Direct Assay of Acyclovir in Tablets

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Journal of Pharmacy and Pharmacology 2017年第12期5卷 841-849页

作者： le Dinh Chi Tran viet Hung Bui Van Trung Doan Cao son . The Department of Analytical Chemistry and Toxicology Hanoi University of Pharmacy Hanoi 110403 Vietnam Director Institute of Drug Quality Control Ho Chi Minh City Ho Chi Minh City 712161 Vietnam The Laboratory of Physical Measurements National Institute of Drug Quality Control Hanoi 110116 Vietnam Director National Institute of Drug Quality Control Hanoi 110116 Vietnam

Estimation of Tropical Forest Structural Characteristics Using ALOS-2 SAR Data

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Advances in Remote Sensing 2016年第2期5卷 131-144页

作者： Luong viet Nguyen Ryutaro Tateishi Hoan Thanh Nguyen Ram C. Sharma Tu Trong To son Mai le Center for Environmental Remote Sensing Chiba University Chiba Japan Space Technology Institute Vietnam Academy of Science and Technology Hanoi Vietnam Institute of Geography Vietnam Academy of Science and Technology Hanoi Vietnam

The potential of ALOS-2 SAR data for the estimation of tropical forest structural characteristics was assessed in vietnam by collecting forest inventory data. The effect of polarization and seasonality of the SAR data on the estimation of forest biomass was analyzed. The combination of HH, HV, and HH/HV polarizations using multiple linear regression did not improve the estimation of biomass compared to using the HV channel independently, as the HH and HH/HV variables were not statistically significant. The dry season HV backscattering intensity was highly sensitive to the biomass compared to the rainy season backscattering intensity. The SAR data acquired in the rainy season with humid and wet canopies was not very sensitive to the biomass. The strong dependence of the biomass estimates with the season of SAR data acquisition confirmed that the choice of right season SAR data is very important for improving the satellite based estimates of the biomass. The validation results showed that the dry season HV polarization could explain 54% variation of the biomass.

关键词： Forest Structure Forest Biomass SAR ALOS-2 Backscattering Intensity Sensitivity Analysis

EXISTENCE AND STABILITY OF PERIODIC AND ALMOST PERIODIC SOLUTIONS TO THE BOUSSINESQ SYSTEM IN UNBOUNDED DOMAINS

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Acta Mathematica Scientia 2022年第5期42卷 1875-1901页

作者： Thieu Huy NGUYEN Truong Xuan PHAM Thi Ngoc Ha VU The Sac le School of Applied Mathematics and Informatics Hanoi University of Science and Technology Vien Toan ung dung va Tin hocDai hoc Bach khoa Hanoi 1DaiCoVietHanoiVietnam Department of Mathematics Faculty of Information TechnologyThuyloi university Khoa Cong nghe Thong tinBo mon ToanDai hoc Thuy loi175 Tay SonDong DaHa NoiViet Nam Thuyloi University Dai hoc Thuy Loi175 Tay SonDong DaHanoiViet Nam

In this paper we investigate the existence and stability of periodic solutions(on a half-line R_(+))and almost periodic solutions on the whole line time-axis R to the Boussinesq system on several classes of unbounded domains of R^(n) in the framework of interpolation *** the linear Boussinesq system we combine the L^(p)—L^(q)-smoothing estimates and interpolation functors to prove the existence of bounded mild ***,we prove the existence of periodic solutions by invoking Massera’s *** also prove the existence of almost periodic *** we use the results of the linear Boussinesq system to establish the existence,uniqueness and stability of the small periodic and almost periodic solutions to the Boussinesq system using fixed point arguments and interpolation *** results cover and extend the previous ones obtained in[13,34,38].

关键词： Boussinesq systems periodic solutions almost periodic solutions unbounded domains smoothing estimates dual estimates interpolation spaces stability

Applied Biofloc Technology for Target Species in the Mekong Delta in vietnam： A Review

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Journal of Environmental Science and Engineering(B) 2017年第4期6卷 165-175页

作者： Nguyen Van Hoa Ta Van Phuong Tran Ngoc Hai Chau Tai Tao le Quoc viet Nguyen Thi Hong Van Huynh Thanh Toi Tran Huu le Vo Nam son Pham Quoc Anh Duy College of Aquaculture and Fisheries (CAF) Cantho University Cantho 270000-910000 Vietnam College of Applied Biology Tay Do University Cantho 270000-910000 Vietnam