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Search Results: 1 - 10 of 11434 matches for " Shimin Cai "
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Personalized recommendation with corrected similarity
Xuzhen Zhu,Hui Tian,Shimin Cai
Computer Science , 2014, DOI: 10.1088/1742-5468/2014/07/P07004
Abstract: Personalized recommendation attracts a surge of interdisciplinary researches. Especially, similarity based methods in applications of real recommendation systems achieve great success. However, the computations of similarities are overestimated or underestimated outstandingly due to the defective strategy of unidirectional similarity estimation. In this paper, we solve this drawback by leveraging mutual correction of forward and backward similarity estimations, and propose a new personalized recommendation index, i.e., corrected similarity based inference (CSI). Through extensive experiments on four benchmark datasets, the results show a greater improvement of CSI in comparison with these mainstream baselines. And the detailed analysis is presented to unveil and understand the origin of such difference between CSI and mainstream indices.
Does the Central Government’s Anti-Corruption Campaign Have an Impact on Corporate Cost Stickiness?  [PDF]
Shimin Wang
American Journal of Industrial and Business Management (AJIBM) , 2018, DOI: 10.4236/ajibm.2018.810139
Abstract: This paper starts with the anti-corruption campaign of the 18th National Congress of the Communist Party of China (CPC), adopts the empirical method to study whether and how the anti-corruption campaign of the central government influences the cost stickiness of enterprises. And the paper further studies whether the anti-corruption campaign has different impacts on enterprises with different property rights. The results show that the cost stickiness of listed companies decreases significantly after the anti-corruption campaign. Compared with non-state-owned enterprises, the cost stickiness of state-owned enterprises weakened less after the anti-corruption campaign started. The research results of this paper show that anti-corruption can restrain the rent-seeking behavior of enterprises and make them apply more resources to normal production and operation activities.
Unfolding Substructures of Complex Networks by Coupling Chaotic Oscillators beyond Global Synchronization Regime
Zhao Zhuo,Shimin Cai,Jie Zhang,Zhongqian Fu
Physics , 2011,
Abstract: In the past decade, synchronization on complex networks has attracted increasing attentions from various research disciplines. Most previous works, however, focus only on the dynamic behaviors of synchronization process in the stable region, i.e., global synchronization. In this letter, we demonstrate that synchronization process on complex networks can efficiently reveal the substructures of networks when the coupling strength of chaotic oscillators is under the lower boundary of stable region. Both analytic and numerical results show that the nodes belonging to the same component in the hierarchical network are tightly clustered according to the Euclidean distances between the state vectors of the corresponding oscillators, and different levels of hierarchy can be systematically unfolded by gradually tuning the coupling strength. When the coupling strengths exceed the upper boundary of stable region, the hierarchy of the network cannot be recognized by this approach. Extensive simulations suggest that our method may provide a powerful tool to detect the hierarchical community structure of complex systems and deep insight into the relationship between structure and dynamics of complex systems.
Predicting missing links via significant paths
Xuzhen Zhu,Hui Tian,Shimin Cai,Tao Zhou
Computer Science , 2014, DOI: 10.1209/0295-5075/106/18008
Abstract: Link prediction plays an important role in understanding intrinsic evolving mechanisms of networks. With the belief that the likelihood of the existence of a link between two nodes is strongly related with their similarity, many methods have been proposed to calculate node similarity based on node attributes and/or topological structures. Among a large variety of methods that take into account paths connecting the target pair of nodes, most of which neglect the heterogeneity of those paths. Our hypothesis is that a path consisting of small-degree nodes provides a strong evidence of similarity between two ends, accordingly, we propose a so-called sig- nificant path index in this Letter to leverage intermediate nodes' degrees in similarity calculation. Empirical experiments on twelve disparate real networks demonstrate that the proposed index outperforms the mainstream link prediction baselines.
Personalized recommendation against crowd's popular selection
Xuzhen Zhu,Hui Tian,Haifeng Liu,Shimin Cai
Computer Science , 2014,
Abstract: The problem of personalized recommendation in an ocean of data attracts more and more attention recently. Most traditional researches ignore the popularity of the recommended object, which resulting in low personality and accuracy. In this Letter, we proposed a personalized recommendation method based on weighted object network, punishing the recommended object that is the crowd's popular selection, namely, Anti-popularity index(AP), which can give enhanced personality, accuracy and diversity in contrast to mainstream baselines with a low computational complexity.
Dual-induced multifractality of human online activity
Yuhao Qin,Zhidan Zhao,Shimin Cai,Liang Gao
Computer Science , 2014,
Abstract: Recent discoveries of human activity reveal the existence of long-term correlation and its relation with the fat-tailed distribution of inter-event times, which imply that there exists the fractality of human activity. However, works further analyzing the category of fractality and its origin still lack. Herein, both the DFA and MFDFA are applied in the analysis of time series of online reviewing activity from Movielens and Netflix. Results show the long-term correlation at individual and whole community level, while the extent of correlation at individual level is restricted to activity level. Such long-term correlation also reveals the fractality of online reviewing activity. In our further investigation of this fractality, we \emph{first} demonstrate it is multifractality, which results from the dual effect of broad probability density function and long-term correlation of time series of online reviewing activity. This result is also verified by three synthesized series. Therefore, we conclude that the combining impact of both broad probability density function and long-term correlation is the origin of multifractality behaving in human online activity.
A Subdivision Scheme for Rational Triangular Bézier Surfaces
计算机科学技术学报 , 1996,
Abstract: An explicit formula is developed to decompose a rational triangular Bezier patch into three non-degenerate rational rectangular Bezier patches of the same degree.This formula yields a stable algorithm to compute the control vertices of those three rectangular subpatches.Some properties of the subdivision are discussed and the formula is illustrated with an example.
The Spectral Method for the Cahn-Hilliard Equation with Concentration-Dependent Mobility
Shimin Chai,Yongkui Zou
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/808216
Abstract: This paper is concerned with the numerical approximations of the Cahn-Hilliard-type equation with concentration-dependent mobility. Convergence analysis and error estimates are presented for the numerical solutions based on the spectral method for the space and the implicit Euler method for the time. Numerical experiments are carried out to illustrate the theoretical analysis.
An Analytical Approximation Method for Strongly Nonlinear Oscillators
Wang Shimin,Yang Lechang
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/958121
Abstract: An analytical method is proposed to get the amplitude-frequency and the phase-frequency characteristics of free/forced oscillators with nonlinear restoring force. The nonlinear restoring force is expressed as a spring with varying stiffness that depends on the vibration amplitude. That is, for stationary vibration, the restoring force linearly depends on the displacement, but the stiffness of the spring varies with the vibration amplitude for nonstationary oscillations. The varied stiffness is constructed by means of the first and second averaged derivatives of the restoring force with respect to the displacement. Then, this stiffness gives the amplitude frequency and the phase frequency characteristics of the oscillator. Various examples show that this method can be applied extensively to oscillators with nonlinear restoring force, and that the solving process is extremely simple.
Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics
Shimin Wang,Zhigang Shen
Energies , 2012, DOI: 10.3390/en5093218
Abstract: The impacts of ventilation ratio and vent balance on cooling load and air flow of naturally ventilated attics are studied in this paper using an unsteady computational fluid dynamics (CFD) model. Buoyancy-driven turbulent ventilations in attics of gable-roof residential buildings are simulated for typical summer conditions. Ventilation ratios from 1/400 to 1/25 combined with both balanced and unbalanced vent configurations are investigated. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively insensitive to the variations in ventilation ratio and vent configuration. The predicted temperature fields are characterized by thermal stratification, except for the soffit regions. It is demonstrated that an increase in ventilation ratio will reduce attic cooling load. Compared with unbalanced vent configurations, balanced attic ventilation is shown to be the optimal solution in both maximizing ventilating flow rate and minimizing cooling load for attics with ventilation ratio lower than 1/100. For attics with ventilation ratios greater than 1/67, a configuration of large ridge vent with small soffit vent favors ventilating air flow enhancement, while a configuration of small ridge vent with large soffit vent results in the lowest cooling energy consumption.
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