C2C电子商务市场整体卖家信用分布研究

随着人们对网上购物的接受程度逐步提高,C2C电子商务越来越火爆。然而由于网络的虚拟性和开放性以及买卖双方的不对称使得诚信成为制约电子商务发展的瓶颈,大部分电子商务平台都采取信用评价体系来解决这一问题,但是效果却不尽如人意。旨在调查现有信用评价体系下的市场整体卖家信分布和结构,发现卖家在各信用等级上的分布曲线呈现出凸向原点的特征,而且随着时间的演进这种趋势愈加明显。通过理论分析我们认为形成倒金字塔形总体信用度分布的根源在于基于交易量的累积信用积分的评级制度、电子商务市场规模的加速增长、市场选择下信用等级和交易量之间的正反馈效应。随着市场规模的扩大,它已不能客观反映卖家诚信,并具有鼓励卖家采取信用炒作等非诚信行为的特点。最后提出了评价体系的改进建议。

一种基于时延约束的社会网络信用分布优化模型

基于时延约束的影响力最大化问题(influence maximization with time-delay constraint,IMTC)定义为在时延约束条件下,选取网络中一部分初始用户,使得影响力传播过程结束后网络中被成功影响的用户数量最多.现有研究工作主要依据网络结构优化影响力传播模型,或改进启发式算法提高初始节点的选取质量,影响力传播过程中的时间延迟特性及时延约束条件往往被忽略.针对这点不足,基于时延约束的信用分布模型(credit distribution with time-delay constraint model,CDTC)综合考虑见面概率和条件激活概率对信用分配进行优化定义,同时将相邻节点之间不断见面并激活对信用分配的阻碍作用映射到传播增量路径中,最后根据信用分布函数,使用基于时延约束的贪心算法GA-TC,递归选取边际收益最大的节点组成初始节点集合.实验结果表明:在CDTC模型上使用GA-TC算法不仅能够保证初始节点的选取质量,而且具有更高的执行效率及更好的行为执行预测能力.

组合信用损失分布的蒙特卡洛模拟

组合损失分布的确定是测量各种组合信用风险的一个先决条件.本文通过对信用风险损失理论进行分析的基础上,分析阐述了利用蒙特卡罗方法模拟组合信用损失的原理和方法,并基于Matlab语言结合实际问题进行仿真实验,实验结果表明该模拟方法能较好地反映组合信用损失的分布特征,具有有效性和实用性.

日本债市违约率、信用评级情况及相关启示

本文基于两家日本本土评级机构对违约的定义及违约率情况,分析了其评级结果检验效果良好的原因,并基于所评主体的信用等级分布情况,发现日本本土评级机构和国际评级机构的评级中枢接近,前者对企业评级较高的主要原因是其对日本主权级别的评级较高。最后,本文对提高我国评级机构评级质量提出了相应建议。

关于城市联合征信信息系统的研究

我国目前尚未形成信用管理体系 ,社会信用状况十分严峻 ,大力加强信用建设作为改善城市经济发展环境非常必要。对建设城市联合征信信息系统的目标和任务 。

Research on E-mail Communication Network Evolution Model Based on User Information Propagation

E-mail communication network evolution model based on user information propagation is studied. First, mathematical representation of weighted e-mail communication network is proposed, and network center parameters of Enron dataset and the distribution of node degree and strength are analyzed. Then, some rules of e-mail communication network evolution are found. Second, the model of e-mail information propagation is described, and e-mail communication network evolution model based on user information propagation is proposed. Lastly, the simulation proves the correctness of the distribution characteristic of degree and strength of the model proposed and then verifies that the model proposed is closer to the real situation of e-mail communication network through parameter comparison. This research provides the basis for other researches on social network evolution and data communication.

Development of Bioinfo-Portal Tool for the Analysis of Genomic and Proteomic Data

The recent explosion of biological data and the concomitant proliferation of distributed databases make it challenging for biologists and bioinformaticians to discover the best data resources for their needs, and the most efficient way to access and use them For the biologist, running bioinformatics analyses involve a time-consuming management of data and tools. Users need support to organize their work, retrieve parameters and reproduce their analyses. They also need to be able to combine their analytic tools using a safe data flow software mechanism. Finally we have designed a system, Bioinfo-Portal, to provide a flexible and usable web environment for defining and running bioinformatics analyses. It embeds simple yet powerful data management features that allow the user to reproduce analyses and to combine tools using an adobe flex tool. Bioinfo-Portal can also act as a front end to provide a unified view of already-existing collections of bioinformatics resources. Users can analyze genomic and proteomic data by using the tools that has been integrated in the portal （tools for alignments, dotplots, motif detection, domain analysis, profile searching and tertiary structure prediction）. The sequences that user obtained from portal＇s nucleotide and protein databases are easily analyzed by the portal tools on the same interface in no time. User can also take benefit from the animations.

Research on the Cloud Computing Technology Application Based on Ubiquitous Network

Ubiquitous breadth of applications and data to quantify the sea and other features need an efficient means to provide information processing technology ensure. This paper analyzes the ubiquitous network application platform and its initial request for all kinds of computing and network resources. The current cloud computing technology distributed processing capabilities, which were assessed. And cloud computing in the future will provide a reference to the proposed application of research on cloud computing technology application and a new application fields.

Wavelet Characterization of the Flow Regime in a Gas-Solid Fluidized Bed

Processes like combustion, pyrolysis or gasification of coal and biomass are typical applications of gas-solid fluidized beds. These reactors normally use silica sand as the inert material inside the bed and the sand particles represent around 95% of the total bed weight. Pressure measurements have been used to characterize the dynamic behavior of fluidized beds since early researches in the area. Pressure fluctuations are generally due to bubbles flow which characterizes the fluidization regime. The present work aims to perform a time-frequency analysis of the pressure signal acquired in an experimental apparatus on different gas-solid flow regimes. Continuous and discrete wavelet transforms were applied and the results were compared with image records acquired simultaneously with the pressure signal. The main frequencies observed are in accordance with the ones obtained through Fourier spectra. The time-frequency distribution of the signal agrees with the phenomena observed in the image record, remarkably for the slugging flow. Some additional research is still necessary to completely characterize the flow regimes using the wavelet scalograms but the present results show that the task is a very promising one.