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The Research of the Recommendation Algorithm in Online Learning
Ruiguo Yu,Zhiyong Cai,Xiuping Du,Muwen He,Zan Wang,Binlan Yang,Peng Chang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.4
Recommendation algorithm is a kind of method in information filtering and has been widely applied on Internet. Collaborative filtering is widely used in the recommendation systems and has turned out to be successful. With the growth of the resources, it is difficult for users to find learning resources that suit for themselves. The recommendation algorithm is required to analyze the behavior of the users and then recommend object of learning. Online judge is a kind of the online learning. People can evaluate their programming ability through online judge. The performance of the different recommendation algorithms is analyzed in this paper and it is proposed that the item-based collaborative filtering recommendation algorithms should be applied into the online learning system. Based on the algorithm, we propose that by pre-processing the data and using user data that have solve large number of problems, we can get a better recommendation result.
Dong Xie,Jiexiong Ding,Fumin Liu,Zhong Jiang,Li Du,Wei Wang,Zhiyong Song 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11
The complex surface machining quality is related to the capacity of the control system, servo drive and mechanical transmission infive-axis CNC machining. The unsuitable parameters result in surface contour errors and other processing abnormal phenomena such astool marks and corrugated surface. In this paper a twisted ruled surface in flank milling is analyzed. The construction features of surfaceand the tool path characteristic of the specimen are listed. The surface cutting velocity is deduced considering the constraints of the acceleration,jerk and other control parameters and the smoothness is modeled. The individual tracking error acquired from servo feed systemmodel is converted to the contour error by homogeneous transformation matrix and Frenet frame, and abnormal tool marks in flank millingare suggested. The cutting experiments conform to simulation; the effect of the dynamic indicators of the CNC machine tool is exploredby the abnormal marks on the machined parts. This approach provides a support for designing specimens and investigating machinetool dynamics performance in working accuracy test.
Hypergraph Game Theoretic Solutions for Load Aware Dynamic Access of Ultra-dense Small Cell Networks
( Xucheng Zhu ),( Yuhua Xu ),( Xin Liu ),( Yuli Zhang ),( Youming Sun ),( Zhiyong Du ),( Dianxiong Liu ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.2
A multi-channel access problem based on hypergraph model in ultra-dense small cell networks is studied in this paper. Due to the hyper-dense deployment of samll cells and the low-powered equipment, cumulative interference becomes an important problem besides the direct interference. The traditional binary interference model cannot capture the complicated interference relationship. In order to overcome this shortcoming, we use the hypergraph model to describe the cumulative interference relation among small cells. We formulate the multi-channel access problem based on hypergraph as two local altruistic games. The first game aims at minimizing the protocol MAC layer interference, which requires less information exchange and can converge faster. The second game aims at minimizing the physical layer interference. It needs more information interaction and converges slower, obtaining better performance. The two modeled games are both proved to be exact potential games, which admit at least one pure Nash Equilibrium (NE). To provide information exchange and reduce convergecne time, a cloud-based centralized-distributed algorithm is designed. Simulation results show that the proposed hypergraph models are both superior to the existing binary models and show the pros and cons of the two methods in different aspects.
Jingxiao Lu,Shutang Wen,Liwei Zhang,Yuxiao Li,Zhiyong Du 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6
Two sets of μc-Si : H films as a function of pressure were fabricated by very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD). Deposition rate, Raman crystallinity, and photo/dark conductivity were investigated under both low and high power conditions. A plasma fluid model and a surface hydride-dependent precursor diffusion model were constructed to understand the evolution of microcrystalline silicon under low and high power conditions. Silyl, hydrogen, ion flux, silyl surface diffusion length are believed to have much influence on film growth rate, crystallinity and photo electronic properties. But the interesting point is that under a certain condition one or more of these parameters dominate μc-Si : H growth, while other parameters have weak influence. Short-life radicals are found to be the possible major factor on the deterioration of photo sensitivity of μc-Si : H films.
Gang Chen,Yu Jin,Jing Wang,Cheng Zhang,Qiang Chen,Hongming Zhang,Xingjian Zhao,Zhiyong Li,Changhai Xie,Zhiming Du 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9
Isothermal compression tests were carried out to study the hot deformation behavior of T2 copper under various conditions. The deformation parameters, such as temperature and strain rate, have strong influence on flow stress and microstructureevolution of the alloy. A unified dislocation density-based model considering dynamic recovery and recrystallization wasestablished. And material parameters of the developed model were optimized by genetic algorithm. Comparisons betweenthe experimental and model data demonstrates that the developed model can precisely describe the flow behavior at quitewide range of deformation conditions. Meanwhile, the designed iterative procedure allows the model to be applied in timevariantdeformation conditions. Processing map and microstructure examination were constructed to optimize the processingwindow of the studied alloy. According to the processing maps, flow instability mainly appeared at low temperatures of500–650 °C and strain rates higher than 0.1 s−1. The optimum deformation parameters of T2 copper was concluded as thetemperature range of 700–800 °C and the strain rate of 0.1–1 s−1.