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Search Results: 1 - 10 of 2240 matches for " PANG Renbo "
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Parallelism and Optimization of Numerical Ocean Forecasting Model Parallelism and Optimization of Numerical Ocean Forecasting Model
XU Jianliang,PANG Renbo,TENG Junhua,LIANG Hongtao,YANG Dandan
- , 2016,
Abstract: According to the characteristics of Chinese marginal seas, the Marginal Sea Model of China(MSMC) has been developed independently in China. Because the model requires long simulation time, as a routine forecasting model, the parallelism of MSMC becomes necessary to be introduced to improve the performance of it. However, some methods used in MSMC, such as Successive Over Relaxation(SOR) algorithm, are not suitable for parallelism. In this paper, methods are developedto solve the parallel problem of the SOR algorithm following the steps as below. First, based on a 3D computing grid system, an automatic data partition method is implemented to dynamically divide the computing grid according to computing resources. Next, based on the characteristics of the numerical forecasting model, a parallel method is designed to solve the parallel problem of the SOR algorithm. Lastly, a communication optimization method is provided to avoid the cost of communication. In the communication optimization method, the non-blocking communication of Message Passing Interface(MPI) is used to implement the parallelism of MSMC with complex physical equations, and the process of communication is overlapped with the computations for improving the performance of parallel MSMC. The experiments show that the parallel MSMC runs 97.2 times faster than the serial MSMC, and root mean square error between the parallel MSMC and the serial MSMC is less than 0.01 for a 30-day simulation(172800 time steps), which meets the requirements of timeliness and accuracy for numerical ocean forecasting products
An Improved Non-isolated LED Converter with Power Factor Correction and Average Current Mode Control  [PDF]
Renbo Xu, Hongjian Li, Yongzhi Li, Changqian Zhang
Circuits and Systems (CS) , 2011, DOI: 10.4236/cs.2011.23034
Abstract: A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.
Research on a High-Efficiency LED Driving Circuit Based on Buck Topology  [PDF]
Renbo Xu, Hongjian Li, Yongzhi Li, Xiaomao Hou
Circuits and Systems (CS) , 2011, DOI: 10.4236/cs.2011.24048
Abstract: A high efficiency LED(Light Emitting Diode) driver based on Buck converter, which could operate under a wide AC input voltage range(85V~265V) and drive a series of high power LEDs, is presented in this paper. The operation principles, power loss factors of the LED driver in this study are analyzed and discussed in detail and some effective ways to improve efficiency are proposed through system design considerations. To verify the feasibility, a laboratory prototype is also designed and tested for an LED lamp which consists of 16 LUMILEDS LEDs in series. Experimental results show that a high efficiency of 92% at I0=350mA can be achieved and the studied driver might be practical for driving high power LEDs. In the last, the overall efficiency over 90% is gained through some experiments under variable input and output voltages and verifies the validity of the designed driver.
Research of an Efficient LED Lighting Driver Based on Boost-Buck Converter  [PDF]
Renbo Xu, Yongzhi Li, Lixin Zhong, Jiaming Liu
Circuits and Systems (CS) , 2014, DOI: 10.4236/cs.2014.56017

Boost-Buck converter is widely used in LED lighting drivers. In this paper, Boost-Buck main circuit related characteristics are firstly discussed, and then a new Boost-Buck high power efficient double loop control strategy is built by adopting error amplifier and integrator control method. It is demonstrated that the new system has many advantages such as high efficiency, fast response, strong anti-interference, good stability after analyses and simulations of its working dynamic characteristics.

Discriminative Supervised Neighborhood Preserving Embedding Feature Extraction for Hyperspectral-image Classification
Renbo Luo,Wenzhi Liao,Youguo Pi
TELKOMNIKA : Indonesian Journal of Electrical Engineering , 2012, DOI: 10.11591/telkomnika.v10i5.1346
Abstract: A novel discriminative supervised neighborhood preserving embedding (DSNPE) method is proposed for feature extraction in classifying hyperspectral remote sensing imagery. DSNPE can preserve the local manifold structure and the neighborhood structure. What’s more, for each data point, DSNPE aims at pulling the neighboring points with the same class label towards it as near as possible, while simultaneously pushing the neighboring points with different labels apart from it as far as possible. Experimental results on two real hyperspectral image datasets are reported to illustrate the performance of DSNPE and to compare it with a few competing methods.
Variance Window Based Car License Plate Localization  [PDF]
Jing Pang
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.29009

In this paper, a new method for discovering the candidate car license plate locations is presented. First, the image is decomposed using a Haar wavelet to get the HL band with vertical edges. Then, the HL band image is binarized using an Otsu threshold. Next a black top-hat algorithm is applied to reduce the effects of interfering large continuous features other than the license plate. At this time, a moving window based modified variance score calculation is made for areas with white pixels. This work found that the top 3 detected rectangle windows correctly locate the license plate regions with a success rate of about 98.2%. Moreover, the proposed method is robust enough to locate the plates in cases where the rough vehicle position has not been previously discovered and the cars are not centered in the image.

Research and Practice on the Cultivation of Engineering Competence for Software Talents in Universities  [PDF]
Xiyu Pang
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.32020
Abstract: This paper analyzes the phenomenon that companies are in need of talents, yet students have difficulty in finding jobs. It proposes new solutions for “Bridging the gap between university education and social demand and cultivating qualified talents for software companies”, that is, to cultivate the students’ competence for software engineering in curriculum design. Besides, it gives a scheme for cultivating the students’ competence for software engineering in curriculum design, and delivers good results in practice.
Solid State Synthesis and Thermoelectric Properties of Mg-Si-Ge System
Renbo SONG,Yazheng LIU,Tatsuhiko AIZAWA,

材料科学技术学报 , 2005,
Abstract: Thermoelectric materials, Mg2Si1-xGex (x=0, 0.2, 0.4, 0.6, 0.8, 1), have been prepared by bulk mechanical alloying (BMA) and hot pressing (HP). The electrical conductivity, Seebeck coefficient and thermal conductivity were measured from room temperature up to about 700 K. The electrical conductivity of all the samples increases with increasing temperature, while the Seebeck coefficient and thermal conductivity decrease with increasing temperature.Mg2Si and Mg2Si0.8Ge0.2 possess negative type of conductivity, while for other compounds it is positive. At the same time, the effect of hot processing condition on thermoelectric properties was also investigated. The maximum figure of merit of Mg2Si0.6Ge0.4 was obtained with the processing parameter of BMA at 600 cycles and hot pressing at 773 K and 1 GPa for 1 h.

SONG Renbo,XIANG Jianying,HOU Dongpo,REN Peidong,

金属学报 , 2010,
Abstract: The characteristics of hot work-hardening for 316L stainless steel have been systematically studied through high temperature compression tests on the Gleeble-1500 thermal simulation testing machine. According to Ludwik true stress-strain model, the experimental data has been regressed by using nonlinear fitting method, and the $n$ value in Ludwik model, a comprehensive index which reflects the competitive result between work-hardening and softening, has been calculated with Crussard-Jaoul method. The dynamic recrystallization and twinning were observed by OM and TEM. The experiments reveal that 316L stainless steel is easy to work-hardening during hot deformation, and deformation rate can effect nC-J-ε curves and variation law; There is no peak stress on its true stress-strain curves, but partial dynamic recrystallization has occurred during hot working process. This incomplete softening mechanism can't counteract the effect of hot work-hardening, so the true stress-strain curves still rise with deformation increasing; In addition, twinning occurred during hot working is one of the major mechanisms of hot work-hardening.
Community Analysis of Social Network in MMOG  [PDF]
Sheng PANG, Changjia CHEN
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2010, DOI: 10.4236/ijcns.2010.32020
Abstract: Massive Multiplayer Online Games (MMOG) have attracted millions of players in recent years. In MMOG, players organize themselves voluntarily and fulfill collective tasks together. Because each player can join different activities, one player may show different social relationship with others in different activities. In the paper we proposed the incremental label propagation algorithm to search the cliques accurately and quickly. Then we analyzed community structure characteristics on multi-activities. It's shown that the existing guild organization cannot satisfy the requirements of multi-activities in MMOG, which motivates us to devise new community communication channels and platforms in future.
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