OALib Journal期刊

ISSN: 2333-9721




2018 ( 19 )

2017 ( 15 )

2016 ( 26 )

2015 ( 234 )


匹配条件: “Xiaofan Hou” ,找到相关结果约6390条。
Finite Element Analysis of High Frequency Breaker Vibrator  [PDF]
Xiaofan Hou, Guoping Yang
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104485
High-frequency breaker vibrator mainly includes three major components of the structure: the vibration box, knife row and bucket teeth. Due to the periodic impact load of the high-frequency breaker, there is a risk of failure if the structure of the exciter is not designed properly, which will seriously affect the working efficiency and service life of the breaker. The static characteristic of the exciter is an important part of evaluating the overall performance of the breaker. It is necessary to do the statics analysis of the exciter to study the stress distribution and the strain state of the breaker. Based on the above reasons, the stress analysis and strain analysis of the finite element modeling of the exciter structure are carried out in this paper. The simplification and constraint handling of the model are discussed.
Decentralized state observer scheme for uncertain time-delay T-S fuzzy interconnected systems

Yanxin ZHANG,Zhongsheng HOU,Xiaofan WANG,

控制理论与应用 , 2006,
Abstract: This paper focuses on a class of T-S fuzzy interconnected systems with time delays and time-varying parameter uncertainties. Observer-based output feedback decentralized controller is designed such that the closed-loop interconnected system is asymptotically stable in the Lyapunov sense in probability for all admissible uncertainties and time delays. Sufficient conditions for robustly asymptotically stability of the systems are given in terms of a set of linear matrix inequalities(LMIs).
The Weak Link: Diagnosing Political and Social Factors in China’s Environmental Issue  [PDF]
Xiaofan Li
Chinese Studies (ChnStd) , 2013, DOI: 10.4236/chnstd.2013.24029
Abstract: China’s thriving economy takes a toll on its environmental sustainability, and recent decades have witnessed an irreversible degradation in China’s environmental conditions. Meanwhile, the environmental issue in China is embedded in a large and complex political and social context that has been undergoing continual and far-reaching transformations. With an attempt to diagnose the weak link and to shed light on solutions for China’s environmental issue, this article explores and analyzes an array of political and social factors: changes in China’s environmental policies and political orientations, conflicts between economic growth and environmental protection, political decentralization and its impact on the environmental issue, and China’s civil society’s role in public awareness and support for environmental protection.
Retrieval of the ground surface reflectance along coast zone and island with MODIS image  [PDF]
Jinji Ma, Xiaofan Li
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.33025
Abstract: A new method based on lookup tables (LUTs) for retrieval of the ground surface reflectance along coastal zones and islands with MODIS (Moderate-resolution imaging spectroradiometer) image was descibed.Through simulation of the AHMAD radiative transfer model, we can retrieve the aerosol optical character with water pixels of MODIS image. Postulating the background is cloudless and the atmosphere on the water is the same as that on the island, we can use the 6S radiative transfer model to compute the LUT about the ground surface reflectance, then use the interpolate method to get the reflectance of the ground surface along coastal zones and islands through the reflectance of the land pixels of MODIS image, the geometric condition and the aerosol optical thickness. The LUT method is applied to determine the ground surface reflectance in Xiamen’s zone from the MODIS image. At last, the results were analyzed and its expectation errors were reported.
Quantitative Bounds for Positive Solutions of a Stevi? Difference Equation
Wanping Liu,Xiaofan Yang
Discrete Dynamics in Nature and Society , 2010, DOI: 10.1155/2010/235808
Abstract: This paper studies the behavior of positive solutions to the following particular case of a difference equation by Stevi? , , where , , , and presents theoretically computable explicit lower and upper bounds for the positive solutions to this equation. Besides, a concrete example is given to show the computing approaches which are effective for small parameters. Some analogous results are also established for the corresponding Stevi? max-type difference equation. 1. Introduction The study regarding the behavior of positive solutions to the difference equation where and was put forward by Stevi? at many conferences (see, e.g., [1–3]). For numerous papers in this area and some closely related results, see [1–39] and the references cited therein. In [4, 24], the authors proved some conditions for the global asymptotic stability of the positive equilibrium to the difference equation given by with Motivated by these papers, the authors of [8] studied the quantitative bounds for the recursive equation (1.2) where , and and quantitative bounds of the form were provided. Exponential convergence was shown to persist for all solutions. The authors also took as an example, and eventually obtained the concrete bounds as follows: In [20], Stevi? investigated positive solutions of the following difference equation: where , and gave a complete picture concerning the boundedness character of the positive solutions to (1.4) as well as of positive solutions of the following counterpart in the class of max-type difference equations: where are positive real numbers. Motivated by the above work and works in [6, 9, 10, 12, 17, 21, 22], our aim in this paper is to discuss the quantitative bounds of the solutions to the following higher-order difference equation: where , and the initial values are positive. Following the methods and ideas from [8], we obtain theoretically computable explicit bounds of the form which are independent of the positive initial values Our results extend those ones in [8], in which the case was considered, and also in some way improve those in [20], in which the case was considered. On the other hand, inspired by the study in [19] we also investigate the quantitative bounds for the positive solutions to the following max-type recursive equation: where and some similar results are established. We want to point out that the boundedness characters of (1.1) and (1.8) for the case and , including our particular case, have been recently solved by Stevi? and presented at several conferences (see also [25]). 2. Auxiliary Results In this section, we will
Evolutionary history of histone demethylase families: distinct evolutionary patterns suggest functional divergence
Xiaofan Zhou, Hong Ma
BMC Evolutionary Biology , 2008, DOI: 10.1186/1471-2148-8-294
Abstract: We performed systematic phylogenetic analysis of these histone demethylase families and uncovered different evolutionary patterns. The KDM1 genes have been maintained with a stable low copy number in most organisms except for a few duplication events in flowering plants. In contrast, multiple genes for JmjC proteins with distinct domain architectures were present before the split of major eukaryotic groups, and experienced subsequent birth-and-death evolution. In addition, distinct evolutionary patterns can also be observed between animal and plant histone demethylases in both families. Furthermore, our results showed that some JmjC subfamilies contain only animal genes with specific demethylase activities, but do not have plant members.Our study improves the understanding about the evolutionary history of KDM1 and JmjC genes and provides valuable insights into their functions. Based on the phylogenetic relationship, we discussed possible histone demethylase activities for several plant JmjC proteins. Finally, we proposed that the observed differences in evolutionary pattern imply functional divergence between animal and plant histone demethylases.One important mechanism for eukaryotic gene regulation is the epigenetic regulation of chromatin structure. The basic unit of chromatin is the nucleosome, which consists of 146 bp of DNA wrapped around an octamer of four histone proteins, H2A, H2B, H3, and H4. Histone proteins can be modified on the N-terminal tail and the modifications can disrupt the interaction between nucleosomes to prevent the packaging of chromatin into higher order structures; also the modified tails can serve as binding sites for chromatin modifiers, facilitating their functions [1]. Histone modifications, such as methylation and acetylation, have been well studied and many of the sites for the modifications are known [1]. For example, methylation can take place on several lysine residues on histone H3 and H4 (H3K4, H3K9, H3K27, H3K36, etc.) and ea
Li Zhang,Xiaofan Zhu
Mediterranean Journal of Hematology and Infectious Diseases , 2012, DOI: 10.4084/mjhid.2012.
Abstract: The limited available data suggest that the rate of early mortality is high and that long-term survival is poor in many developing countries. Death from bleeding and infection during chemotherapy, relapse and treatment abandonment are among the main cause of treatment failure in APL children. The status of children APL treatment in China is not described in general.
Evolution of a large online social network
Haibo Hu,Xiaofan Wang
Physics , 2009, DOI: 10.1016/j.physleta.2009.02.004
Abstract: Although recently there are extensive research on the collaborative networks and online communities, there is very limited knowledge about the actual evolution of the online social networks (OSN). In the Letter, we study the structural evolution of a large online virtual community. We find that the scale growth of the OSN shows non-trivial S shape which may provide a proper exemplification for Bass diffusion model. We reveal that the evolutions of many network properties, such as density, clustering, heterogeneity and modularity, show non-monotone feature, and shrink phenomenon occurs for the path length and diameter of the network. Furthermore, the OSN underwent a transition from degree assortativity characteristic of collaborative networks to degree disassortativity characteristic of many OSNs. Our study has revealed the evolutionary pattern of interpersonal interactions in a specific population and provided a valuable platform for theoretical modeling and further analysis.
Disassortative mixing in online social networks
Haibo Hu,Xiaofan Wang
Physics , 2009, DOI: 10.1209/0295-5075/86/18003
Abstract: The conventional wisdom is that social networks exhibit an assortative mixing pattern, whereas biological and technological networks show a disassortative mixing pattern. However, the recent research on the online social networks modifies the widespread belief, and many online social networks show a disassortative or neutral mixing feature. Especially, we found that an online social network, Wealink, underwent a transition from degree assortativity characteristic of real social networks to degree disassortativity characteristic of many online social networks, and the transition can be reasonably elucidated by a simple network model that we propose. The relations among network assortativity, clustering, and modularity are also discussed in the paper.
Geometrical information on the solar shape: high precision results with SDO/HMI
Xiaofan Wang,Costantino Sigismondi
Physics , 2012, DOI: 10.1017/S1743921313002974
Abstract: The uncertainty of measurement of solar diameter is depending on the observational time scale. Full-disc images of SDO/HMI and the images from ground observations in Huairou Solar Observing Station have been analyzed to get the values of solar diameter. The satellite observations reach a very high precision, but the absolute image scale still need to be calibrated. The solar oblateness is a more challenging measurement than the diameter, since the signal amplitude is a few milli-arcseconds. It is a relative measurement, then not affected by the pixel scale calibration required by the diameter measurement. But the results are strongly dependent on the state of instrument such as focus plane deformation and on the calculation process.

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