ESTIMATION OF WAVE CHARACTERISTICS IN EAST VIETNAM SEA USINGWAM MODEL

WAM (WaveModeling) is a third generation wave model developed by WAMDI Group which describes the evolution of a two-dimensional ocean wave spectrum under the effects of winds, currents, bottom and non-linear wave-wave interactions. The model runs for deep and shallow waters and includes depth and current refraction. This study used the WAM cycle 4.5 with model domain which is covered from 990E to 1210E and 00N to 250N with a resolution of ∆X = ∆Y = 0.250. Bathymetry of East Vietnam Sea (EVS) was taken from ‘ETOPO5’ data set of National Geophysical Data Center, Colorado, USA with resolution of 5’ (≈ 9 km). Wind velocities were obtained from 6 hourly NCEP/NCAR reanalysis data, USA with resolution of ∆X = ∆Y = 0.250. Study results show that during NE monsoon period, the main wave direction in EVS was NE and vice versa during SW monsoon period. Regions of greatest wave height were in the central and northern part of the EVS. Statistic of computed wave characteristics from 1987 to 2011 shows that wave regime in the offshore region of Nhatrang coast has two main wave directions that are NE with 40.82% of occurrence, SSW with 20.15% of occurrence. NE monsoon wave dominated from October to April of the next year, SW monsoon wave dominated from June to August. May and September are transitional periods. Assimilation of wind data with resolution of ∆X = ∆Y = 0.250 permits the model to be used to simulate the wave field during typhoon activity in EVS

THE WORK-OUTS TO OPTIMIZE THE EFFICIENCY FOOTWORK – A CASE STUDY FOR TALENTED FEMALE TABLE TENNIS ATHLETES AT THE AGE OF 14-15 IN VINH LONG PROVINCE, VIETNAM

The purpose of this study was to build up and evaluate the application of work-outs about the efficiency of footwork for talented female table tennis athletes. 08 healthy female talented table tennis athletes at the age of 14-15 in Vinh Long province were chosen to participate in the 8-week pre-season training. Results indicated that the 20 work-outs were selected to improve the efficiency footwork through the basis of training principle, participant’ characteristics, previous studies, and expert interviews. Besides, there were significant differences in all 06 tests to evaluate the footwork ability after the experiment. Moreover, the percentage of change indicated increased, from the objective perspective, we found that the growth rate was still at the moderate level (from 2.72% to 6.07%). Therefore, it is necessary to apply the 20 work-outs more flexibly and closely to improve the efficiency of footwork in different training phases next year. It was concluded that the application of the 20 work-outs about the efficiency of footwork had positive effects on female talented table tennis athletes. Future studies should be conducted on a group of males, diverse in training levels, and/or on the other sports group that need to promote footwork ability.   Article visualizations

Analysis and Simulation of MRC Diversity Reception in Correlated Composite Nakagami-Lognormal Fading Channels

The physical meaning of the composite Nakagami-lognormal fading model is not well understood by many researchers using the model. The signal power transfer and transform at the interface between the global lognormal shadowing sub-channels and the local Nakagami multipath sub-channels in the presence of correlation between these diversity sub-channels is rather complex. This is the main reason why a thorough analysis or a simulation model is absent to date for the case of correlated composite Nakagami-lognormal diversity channels. This paper presents a novel technique for the estimation of the probability density function (PDF) of the signal-to-noise (SNR) at the output of a maximum ratio combining (MRC) receiver operating in correlated composite diversity fading channels. The PDF is estimated using the recently proposed two-point lossless moment generating function (MGF) matching technique and a closed-form expression for the bit-error rate (BER) for QPSK signal is consequently presented using the Gauss-Hermite polynomial approximation. The paper also presents the complex Monte-Carlo simulation model for the MRC reception and BER counting in correlated composite Nakagami-lognormal fading channels

Multiobjective Logistics Optimization for Automated ATM Cash Replenishment Process

In the digital transformation era, integrating digital technology into every aspect of banking operations improves process automation, cost efficiency, and service level improvement. Although logistics for ATM cash is a crucial task that impacts operating costs and consumer satisfaction, there has been little effort to enhance it. Specifically, in Vietnam, with a market of more than 20,000 ATMs nationally, research and technological solutions that can resolve this issue remain scarce. In this paper, we generalized the vehicle routing problem for ATM cash replenishment, suggested a mathematical model and then offered a tool to evaluate various situations. When being evaluated on the simulated dataset, our proposed model and method produced encouraging results with the benefits of cutting ATM cash operating costs