基于T检验与Fuzzy法的众包影响因素分析及实证研究

在不确定的复杂外包环境下众包模式受到诸多因素影响。在双轮复合问卷调查的基础上对众包影响因素进行分析统计,构建研究框架模型并从多个角度对调查数据样本进行T检验,利用模糊多层次评判法对提炼出的众包影响因素进行综合因子评判,并结合算例加以实证研究。结果表明:互联网网民数量、中介机构数量、涉及众包业务企业数量和出台外包相关法规数量四个因素与众包发展显著正相关,并获得企业普遍较高的支持率。根据实证测评结果有针对性地提出中国众包跨越式发展的具体对策,也为十二五中国大力实施外包新兴产业政策提供理论支持,助力中国众包产业转型升级的推进。     

Activist Identity as a Motivational Resource: Dynamics of (Dis)empowerment at the G8 Direct Actions,Gleneagles, 2005

This paper describes a study examining how different groups at some of the G8 protests, Gleneagles, 2005, negotiated experiences of (dis)empowerment. A recent survey of protest events speculated that, as a function of their social identities, experienced activists have available to them particular strategies to counter disempowerment and hence provide motivation for continued involvement. The G8 direct actions in Gleneagles provided an opportunity to examine such dynamics of (dis)empowerment in situ. An ethnographic study was carried out covering the duration of the Gleneagles events, including interviews with forty participants. Two key findings were as follows. First, across the protest group as a whole there was little unification and no agreed definition of success. Consequently, feelings of empowerment varied systematically across the sample. The second key finding concerned changes in definitions of success among some participants. For experienced activists, their activist identity entailed access to sets of arguments and discussions with fellow activists which allowed potentially disempowering events to be (re-)interpreted positively. An example was the re-evaluation of the importance of the Stirling campsite, which came to be seen by some as a key achievement. We argue in conclusion, however, that some activist strategies to maintain empowerment, while appearing to be based on a radical position, can operate as a break on escalation. The analysis as a whole suggests both the subjective and objective significance of identity and empowerment in movement dynamics.     

MUSIC FOR NOTHING OR,I WANT MY MP3

With the public discourse around filesharing veering towards punitive extremes, our aim in this essay is to reframe the issue in two ways. First, we argue that the filesharing debates are ‘too economic’, insofar as they reduce a multi-faceted phenomenon to a single issue: financial loss resulting from the theft of intellectual property. Lost in such arguments is the fact that music routinely circulates through the culture in myriad ways that have little (if anything) to do with commerce and capitalism, and everything to do with affect and affiliation. Second, the filesharing debates are simultaneously ‘not economic enough’, insofar as they evade the financial complexities of the music business in favor of an overly simplistic equation: ‘downloaded music’ leads directly to ‘lost sales revenues’. A more robust analysis of the music industry's standard economic practices, however, undercuts both its economic claims about the negative effects of filesharing on sales and its moral claims to be defending helpless musicians from downloading ‘thieves’.     

G20峰会的实施效果及其反思

G20峰会已经过去了一年多时间,但其实际效果却远远没有预期的那么显著,国际金融危机的阴影正在逐渐散去,但峰会对此产生的作用却十分有限。除此之外,在国际经济中对金融的监管依然有名无实、避税天堂仍然猖獗、贸易保护更是层出不穷,这些峰会原本希望遏制的现象并没有得到实质性改善,其中蕴含的道理值得我们深思。     

3G时代我国移动电子商务的安全问题与应对策略

从技术、管理和法律三个角度出发,阐述了目前我国移动电子商务存在着无线通信技术自身缺陷、无线网络标准缺陷、病毒和黑客攻击、移动终端安全管理、移动商务平台运营管理漏洞、网络交易信用缺失以及基于位置的服务等造成的安全问题和安全威胁,分析了造成移动电子商务安全问题的技术、市场、配套政策等原因及其危害性和造成的损失,最后针对性地提出了端到端策略、安全技术防护、安全管理等治理策略。     

Reliability Analysis of Unrepairable Systems with k-out-of-m:G Subsystems Subject to Suspended Animation

Two unrepairable series structure systems with k-out-of-m:G subsystems and spares are investigated. The first one consists of a k-out-of-m:G subsystem and a series subsystem while the other consists of two k-out-of-m:G subsystems. The systems have identical components with identical lifetime distributions and the working components are suspended as soon as the systems are down. Two Markov models are proposed for the reliability analysis of such systems and closed form results on the reliability and the mean time to failure (MTTF) are presented. Numerical examples are given to illustrate the impact of several parameters on the reliability of the systems.     

Comparing distributions of time to onset of disease in animal tumorigenicity experiments

The cause-of-death test of Peto et al.(1980)pools information from a Hoel-Walburg test on incidental tumors with information from a logrank test on fatal tumors in order to compare the tumor rate of a group of rodents exposed to a carcinogen against the tumor rate of a group of unexposed animals. The cause-of-death test, which can arise as a partial likelihood score test from a model that assumes proportional odds for tumor prevalence and proportional hazards for tumor mortality, is not, in general, a direct test for equality of tumor onset distributions for occult tumors that are observed in both fatal and incidental contexts. This paper develops a direct cause-of-death test for comparing distributions of time to onset of occultumors. The test is derived as a partial likelihood score test under an assumed proportional hazards model for tumor onset distributions. The size and power of the proposed test are compared in a Monte Carlo simulation study to the size and power of competitive procedures, including procedures that do not require cause-of-death information.     

A cluster‐sample approach for Monte Carlo integration using multiple samplers

A computational problem in many fields is to estimate simultaneously multiple integrals and expectations, assuming that the data are generated by some Monte Carlo algorithm. Consider two scenarios in which draws are simulated from multiple distributions but the normalizing constants of those distributions may be known or unknown. For each scenario, existing estimators can be classified as using individual samples separately or using all the samples jointly. The latter pooled‐sample estimators are statistically more efficient but computationally more costly to evaluate than the separate‐sample estimators. We develop a cluster‐sample approach to obtain computationally effective estimators, after draws are generated for each scenario. We divide all the samples into mutually exclusive clusters and combine samples from each cluster separately. Furthermore, we exploit a relationship between estimators based on samples from different clusters to achieve variance reduction. The resulting estimators, compared with the pooled‐sample estimators, typically yield similar statistical efficiency but have reduced computational cost. We illustrate the value of the new approach by two examples for an Ising model and a censored Gaussian random field. The Canadian Journal of Statistics 41: 151–173; 2013 © 2012 Statistical Society of Canada     

Bayesian Inference and Prediction in an M/G/1 with Optional Second Service

In this article, we exploit the Bayesian inference and prediction for an M/G/1 queuing model with optional second re-service. In this model, a service unit attends customers arriving following a Poisson process and demanding service according to a general distribution and some of customers need to re-service with probability “p”. First, we introduce a mixture of truncated Normal distributions on interval (? ∞, 0) to approximate the service and re-service time densities. Then, given observations of the system, we propose a Bayesian procedure based on birth-death MCMC methodology to estimate some performance measures. Finally, we apply the theories in practice by providing a numerical example based on real data which have been obtained from a hospital.