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Search Results: 1 - 10 of 14089 matches for " Lei Sipeng "
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Reproduction strategy of Trias verrucosa (Orchidaceae) from China

Liu Zhongjian,Chen Lijun,Lei Sipeng,Rao Wenhui,Li Liqiang,

生态学报 , 2007,
Abstract:
The Triangle Inequality and Its Applications in the Relative Metric Space  [PDF]
Zhanjun Su, Sipeng Li, Jian Shen
Open Journal of Discrete Mathematics (OJDM) , 2013, DOI: 10.4236/ojdm.2013.33023
Abstract:

Let C be a plane convex body. For arbitrary points , a,b ∈E ndenote by │ab│ the Euclidean length of the line-segment ab. Let a1b1 be a longest chord of C parallel to the line-segment ab. The relative distance dc(a,b) between the points a and b is the ratio of the Euclidean distance between a and b to the half of the Euclidean distance between a1 and b1. In this note we prove the triangle inequality in E2 with the relative metric dc( .,.), and apply this inequality to show that 6≤l(P)≤8, where l(P) is the perimeter of the convex polygon P measured in the metric dp

Space-Time Cluster Analysis of Tuberculosis Incidence in Beijing, China  [PDF]
Gehendra Mahara, Mina Karki, Kun Yang, Sipeng Chen, Wei Wang, Xiuhua Guo
Journal of Tuberculosis Research (JTR) , 2018, DOI: 10.4236/jtr.2018.64027
Abstract: Tuberculosis is one of the top killer diseases in the globe. The aim of this study was to explore the geographic distribution patterns and clustering characteristics of the disease incidence in terms of both space and time with high relative risk locations for tuberculosis incidence in Beijing area. A retrospective space-time clustering analysis was conducted at the districts level in Beijing area based on reported cases of sputum smear-positive pulmonary tuberculosis (TB) from 2005 to 2014. Global and local Moran’s I, autocorrelation analysis along with Ord (Gi*) statistics was applied to detect spatial patterns and the hotspot of TB incidence. Furthermore, the Kuldorff’s scan statistics were used to analyze space-time clusters. A total of 40,878 TB cases were reported in Beijing from 2005 to 2014. The annual average incidence rate was 22.11 per 100,000 populations (ranged from 16.55 to 25.71). The seasonal incidence occurred from March to July until late autumn. A higher relative risk area for TB incidence was mainly detected in urban and some rural districts of Beijing. The significant most likely space-time clusters and secondary clusters of TB incidence were scattered diversely in Beijing districts in each study year. The risk population was mainly scattered in urban and dense populated districts, including in few rural districts.
Crystallization properties of Sn--doped Ge--Sb--Te phase--change films
Sn掺杂Ge-Sb-Te相变薄膜的晶化特性

GU Sipeng,HOU Lisong,ZHAO Qitao,
顾四朋
,侯立松,赵启涛

材料研究学报 , 2004,
Abstract: Sn-doped Ge_2Sb_2Te_5 thin films were prepared by RF-sputtering.The effect of Sn- content on their crystallization properties was studied by XRD and DSC.The XRD spectra of the films in the as-deposited and heat-treated states showed that the films changed from amorphous to crystalline states due to heat-treatment and Sn-Te phase appeared.Using DSC data of the amorphous film materials,the activation energies were calculated by measuring the peak crystallization temperatures at different heating rates.It was found that the Ge-Sb-Te-Sn samples have higher activation energy of crystallization than that of the Ge_2Sb_2Te_5 sample.It is concluded from these results that Sn-doping can increase the crystallization rate of the Ge_2Sb_2Te_5 phase-change material,and thereby increase the erasing speed of the material for rewritable optical storage.
Perfectly Matched Layer for an Elastic Parabolic Equation Model in Ocean Acoustics Perfectly Matched Layer for an Elastic Parabolic Equation Model in Ocean Acoustics
XU Chuanxiu,ZHANG Haigang,PIAO Shengchun,YANG Shi'e,SUN Sipeng,TANG Jun
- , 2017,
Abstract: The perfectly matched layer(PML) is an effective technique for truncating unbounded domains with minimal spurious reflections. A fluid parabolic equation(PE) model applying PML technique was previously used to analyze the sound propagation problem in a range-dependent waveguide(Lu and Zhu, 2007). However, Lu and Zhu only considered a standard fluid PE to demonstrate the capability of the PML and did not take improved one-way models into consideration. They applied a [1/1] Padé approximant to the parabolic equation. The higher-order PEs are more accurate than standard ones when a very large angle propagation is considered. As for range-dependent problems, the techniques to handle the vertical interface between adjacent regions are mainly energy conserving and single-scattering. In this paper, the PML technique is generalized to the higher order elastic PE, as is to the higher order fluid PE. The correction of energy conserving is used in range-dependent waveguides. Simulation is made in both acoustic cases and seismo-acoustic cases. Range-independent and range-dependent waveguides are both adopted to test the accuracy and efficiency of this method. The numerical results illustrate that a PML is much more effective than an artificial absorbing layer(ABL) both in acoustic and seismo-acoustic sound propagation modeling
空间影响域覆盖最大的航标自动选取方法
A Method for Selecting Aids to Navigation Automatically Based on the Maximal Covering of Their Spatial Influence Domains

李思鹏, 张立华, 贾帅东
LI Sipeng
, ZHANG Lihua, JIA Shuaidong

- , 2017, DOI: 10.13203/j.whugis20150460
Abstract: 针对当前海图制图综合中航标手工选取作业效率低、选取结果受限于作业人员业务水平和工作态度等不足,提出了一种基于空间影响域覆盖最大的航标自动选取方法。通过定义空间影响域,创建空间影响域模型,加权评估航标地理位置重要性,设计空间影响域覆盖最大的分轮次自动选取策略,实现了航标的自动选取。实验结果表明:本文方法实现了航标的自动选取且结果符合《中国航海图编绘规范》要求,能避免手工选取可能存在的明显失误和不同作业人员可能导致的结果不一致性,作业效率明显高于当前普遍使用的手工选取方法
Study on Community Cooperation Game of the Main Body in Regional Innovation Ecosystem  [PDF]
Lei Lei, Song Wei
American Journal of Industrial and Business Management (AJIBM) , 2017, DOI: 10.4236/ajibm.2017.79076
Abstract: Cooperative innovation of heterogeneous population is more and more important in regional innovation ecosystem, and cross-border cooperation has become one of the effective ways to break through the predicament of ecological niche development. However, the existence of opportunistic behavior will restrain the cooperation motivation among the main communities and threaten the stability of the ecosystem population cooperation network. In order to avoid possible speculation, participants tend to make commitments beforehand. However, how can the commitment effectively avoid partner speculation so as to improve cooperation performance? In this paper, we will study the community game strategy of main body in innovation under multivariate uncertainty, and analyze the impact of commitment on collaborative innovation action.
Researches on the Duality Innovation Strategies for Scientific Small and Medium Enterprises  [PDF]
Lei Lei, Wei Song
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.59017
Abstract:
The realization path and mode selection issues for the duality innovation of the scientific small and medium enterprises (SMEs) haven’t obtained a good settlement in China. With the questionnaire investigation and layered regression analysis for 292 scientific SMEs, this paper carried out researches on the realization path and mode selection for the duality innovation for scientific SMEs. The results show that relying purely on the interior path and correspondent paths to realize the duality innovation has no significant lifting functions for the enterprises’ performance, relying purely on the exterior paths and correspondent modes to realize the duality innovation will pose harms to the enterprises’ performance, and by taking the interactive paths between the interior path and exterior path to realize the duality innovation has significant lifting functions for the enterprises’ performance. The duality innovation mode with the interior development innovation and the exterior exploration innovation under this path is lifting the enterprises’ performance to the greatest extent.
Influence of Ar/N2 Flow Rate on Structure and Property for TaN/NbN Multilayered Coatings
Xuehua ZHANG,Yuanbin KANG,Sipeng LIU,Qiang LI,Ying YANG,Xiangyun DENG,Dejun LI,
Xuehua
,ZHANG,Yuanbin,KANG,Sipeng,LIU,Qiang,LI,Ying,YANG,Xiangyun,DENG,Dejun,LI

材料科学技术学报 , 2007,
Abstract: TaN/NbN multilayered coatings with nanoscale bilayer periods were synthesized at different Ar/N2 flow rates by RF (radio frequency) magnetron sputtering. XRD (X-ray diffraction) and Nano Indenter System were employed to investigate the influence of Ar/N2 flow rate (FAr:FN2) on microstructure and mechanical properties of the coatings. The low-angle XRD pattern indicated a well-defined composition modulation and layer structure of the multilayered coating. All multilayered coatings almost revealed higher hardness than the rule-of-mixtures value of monolithic TaN and NbN coatings. At FAr:FN2=10, the multilayered coating possessed desirable hardness, elastic modulus, internal stress, and fracture resistance, compared with ones synthesized at other Ar/N2 flow rates. The layered structure with strong mixture of TaN (110), (111), (200) and Nb2N (101)textures should be related to the enhanced mechanical properties.
Hierarchical Hypercube Based Pairwise Key Establishment Scheme for Sensor Networks  [PDF]
Lei WANG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.22016
Abstract: Security schemes of pairwise key establishment, which enable sensors to communicate with each other se-curely, play a fundamental role in research on security issue in wireless sensor networks. A general frame-work for key predistribution is presented, based on the idea of KDC (Key Distribution Center) and polyno-mial pool schemes. By utilizing nice properties of H2 (Hierarchical Hypercube) model, a new security mechanism for key predistribution based on such model is also proposed. Furthermore, the working per-formance of tolerance resistance is seriously inspected in this paper. Theoretic analysis and experimental fig-ures show that the algorithm addressed in this paper has better performance and provides higher possibilities for sensor to establish pairwise key, compared with previous related works.
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