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Search Results: 1 - 10 of 17206 matches for " Xiangfeng Bo "
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Experimental Investigation of Boundary Layer Characteristics on Blade Surface under Different Inlet Flow Conditions  [PDF]
Xiangfeng Bo, Bo Liu, Pengcheng Zhao, Zhiyuan Cao
Energy and Power Engineering (EPE) , 2010, DOI: 10.4236/epe.2010.24044
Abstract: In this paper, an experimental study is conducted on cascade boundary layer under different inlet conditions. New method is used to measure the total pressure in blade surface boundary layer directly using total pressure probe. Total pressure in both suction and pressure surfaces are acquired at different inlet conditions by changing incidence angle and inlet Mach number. In addition, a series of parameters related to boundary layer characteristics are calculated. The objective of the experiment is to investigate the influence of inlet flow conditions on them. The results indicate that influence of incidence angle is significant when other conditions are the same. Displacement thickness, momentum thickness as well as other parameters display some disciplines for variation. In contrast, inlet Mach number has only a small influence in that boundary layer becomes a litter thinner with increasing Mach number. Comparisons of experimental results with theoretical expectations demonstrate that the method in this experiment is effective and reliable.
Experimental Investigation of Unsteady Pressure on an Axial Compressor Rotor Blade Surface  [PDF]
Qingwei Wang, Bo Liu, Xiaorong Xiang, Xiangfeng Bo, Weimin Hou
Energy and Power Engineering (EPE) , 2010, DOI: 10.4236/epe.2010.22019
Abstract: The inherent unsteady pressure fluctuations on the rotating blade suction surface of an axial compressor were experimentally measured by directly mounting five high response miniature pressure transducers into the rotor blade along a streamline at 50% span respectively. The results show that the unsteady pressure fluctuations of rotor blade surface could be measured successfully by this means. The relations about the period, altitude of unsteady pressure with rotating speed, the discipline of pressure fluctuation along the streamwise direction were obtained.
Multi-scale analysis on wintering habitat selection of Reeves''s Pheasant (Syrmaticus reevesii) in Dongzhai National Nature Reserve, Henan Province, China

Jiliang Xu,Xiaohui Zhang,Zhengwang Zhang,Guangmei Zheng,Xiangfeng Ruan,Jiagui Zhu,Bo Xi,

生态学报 , 2006,
Abstract: Reeves's Pheasant (Syrmaticus reevesii), endemic to China, is an endangered species of pheasants. The wintering habitat selection by the species was investigated at three scales (10, 115 m and 250 m) in Dongzhai National Nature Reserve from 2000 to 2002. At each scale, a range of habitat variables were compared between the used and the control sites. At the smallest scale (10 m), the variables influencing wintering habitat selection were slope, tree cover, and the interaction between the cosine of slope aspect and the shrub height. At the mid-scale (115 m), the area of shrub, the area of broad-leaved forest, and the area of conifer forest were the key factors. At the largest scale (250 m), broad-leaved and conifer forest coverages and their interaction were the key factors. According to the lowest AIC and AICc values at the mid-scale, the characteristics at this scale were stated as the ultimate factors influencing the habitat selection of the bird. When a range of habitat variables at all scales within a multivariate regression were considerred, the most important variables were conifer forest coverage at the mid-scale, broad-leaved forest coverage, and the interaction between the conifer forest and shrub coverages at the large-scale, and the distance to beach and farmland. These results highlight the importance of multiscale analyses when habitat selection by pheasants are considerred.
Ito formulas for functionals of elliptic diffusions
Xiangfeng Yang
Applied Mathematical Sciences , 2012,
Systematic Curation of miRBase Annotation Using Integrated Small RNA High-Throughput Sequencing Data for C. elegans and Drosophila
Xiangfeng Wang
Frontiers in Genetics , 2011, DOI: 10.3389/fgene.2011.00025
Abstract: MicroRNAs (miRNAs) are a class of 20–23 nucleotide small RNAs that regulate gene expression post-transcriptionally in animals and plants. Annotation of miRNAs by the miRNA database (miRBase) has largely relied on computational approaches. As a result, many miRBase entries lack experimental validation, and discrepancies between miRBase annotation and actual miRNA sequences are often observed. In this study, we integrated the small RNA sequencing (smRNA-seq) datasets in Caenorhabditis elegans and Drosophila melanogaster and devised an analytical pipeline coupled with detailed manual inspection to curate miRNA annotation systematically in miRBase. Our analysis reveals 19 (17.0%) and 51 (31.3%) miRNAs entries with detectable smRNA-seq reads have mature sequence discrepancies in C. elegans and D. melanogaster, respectively. These discrepancies frequently occur either for conserved miRNA families whose mature sequences were predicted according to their homologous counterparts in other species or for miRNAs whose precursor miRNA (pre-miRNA) hairpins produce an abundance of multiple miRNA isoforms or variants. Our analysis shows that while Drosophila pre-miRNAs, on average, produce less than 60% accurate mature miRNA reads in addition to their 5′ and 3′ variant isoforms, the precision of miRNA processing in C. elegans is much higher, at over 90%. Based on the revised miRNA sequences, we analyzed expression patterns of the more conserved (MC) and less conserved (LC) miRNAs and found that, whereas MC miRNAs are often co-expressed at multiple developmental stages, LC miRNAs tend to be expressed specifically at fewer stages.
Precise asymptotics for large deviations of integral forms
Xiangfeng Yang
Mathematics , 2012,
Abstract: For suitable families of locally infinitely divisible Markov processes $\{\xi^{{\epsilon}}_t\}_{0\leq t\leq T}$ with frequent small jumps depending on a small parameter $\epsilon>0,$ precise asymptotics for large deviations of integral forms $\mathbb{E}^{\epsilon}[\exp\{{\epsilon}^{-1}F(\xi^{\epsilon})\}]$ are proved for smooth functionals $F.$ The main ingredient of the proof in this paper is a recent result regarding the asymptotic expansions of the expectations $\mathbb{E}^{\epsilon}[G(\xi^{\epsilon})\}]$ for smooth $G.$ Several connections between these large deviation asymptotics and partial integro-differential equations are included as well.
Upper tail probabilities of integrated Brownian motions
Fuchang Gao,Xiangfeng Yang
Mathematics , 2014, DOI: 10.1007/s11425-015-4981-9
Abstract: We obtain new upper tail probabilities of $m$-times integrated Brownian motions under the uniform norm and the $L^p$ norm. For the uniform norm, Talagrand's approach is used, while for the $L^p$ norm, Zolotare's approach together with suitable metric entropy and the associated small ball probabilities are used. This proposed method leads to an interesting and concrete connection between small ball probabilities and upper tail probabilities (large ball probabilities) for general Gaussian random variable in Banach spaces. As applications, explicit bounds are given for the largest eigenvalue of the covariance operator, and appropriate limiting behaviors of the Laplace transforms of $m$-times integrated Brownian motions are presented as well.
Strategy of Enhancing Corporate Competitiveness through Operational Digitalization: Case of Axa France  [PDF]
Thierry Fleury Medard Denamguere, Xiangfeng Wu, Sokai Wiltord, Padou Maxime
American Journal of Industrial and Business Management (AJIBM) , 2018, DOI: 10.4236/ajibm.2018.86098
Abstract: It has been several years since trade was born between companies and different nations, or the World Trade Organization (1994) completed the idea in the context of carrying out their commercial activity without having many barriers. The evolution of the new technology has allowed a new economic boom, in order to reinforce and reinvigorate the capacity of human resources, making a state of place on the digitalization requiring a strategy of the company in the digitization and the practices to the method, going through a feasibility study that the group Axa had looked into, in order to be able to engage in competitiveness. This study has allowed us, therefore, to give concrete proposals related to the situation in which the group is complementing the work that has already been done by our predecessors, to be able to possess economic, political and cultural reforms.
Automatic Discovery of Semantic Relations Based on Association Rule
Xiangfeng Luo,Kai Yan,Xue Chen
Journal of Software , 2008, DOI: 10.4304/jsw.3.8.11-18
Abstract: Automatic discovery of semantic relations between resources is a key issue in Web-based intelligent applications such as document understanding and Web services. This paper explores how to automatically discover the latent semantic relations and their properties based on the existing association rules. Through building semantic matrix by the association rules, four semantic relations can be extracted using union and intersection in set theory. By building a cyclic graph model, the transitive path of association relation is discovered. Document-level keywords and domain-level keywords as well as their parameters are analyzed to improve the discovery accuracy. Rules can be gained from the experiments to optimize the discovery processes for relations and properties. Further experiments validate the effectiveness and efficiency of the relation discovery algorithms, which can be applied in Web search, intelligent browsing and Web service composition.
Comparison for upper tail probabilities of random series
Fuchang Gao,Zhenxia Liu,Xiangfeng Yang
Mathematics , 2013,
Abstract: Let $\{\xi_n\}$ be a sequence of independent and identically distributed random variables. In this paper we study the comparison for two upper tail probabilities $\mathbb{P}\{\sum_{n=1}^{\infty}a_n|\xi_n|^p\geq r\}$ and $\mathbb{P}\{\sum_{n=1}^{\infty}b_n|\xi_n|^p\geq r\}$ as $r\rightarrow\infty$ with two different real series $\{a_n\}$ and $\{b_n\}.$ The first result is for Gaussian random variables $\{\xi_n\},$ and in this case these two probabilities are equivalent after suitable scaling. The second result is for more general random variables, thus a weaker form of equivalence (namely, logarithmic level) is proved.
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