摘要：This study focused on differences in vehicle-to-vehicle radio channel characteristics in the same region but different traffic density and speeds at 5.9 GHz(congestion and non-congestion). The continuous measurement campaign was conducted on a city expressway through the complex dense urban area in Wuhan, China. Small-scale channel characteristics including power delay profile, amplitude fading distribution, K-factor, delay spread and Doppler shift were obtained, respectively. Specifically, the cumulative distribution function of root mean square delay spreads and root mean square Doppler spreads in the non-congested scenario and congested scenario were all fitted well with Lognormal distribution. We also found out that different intensity of traffic and speed of vehicles have little effect on root mean square delay spreads, but have a big impact on root mean square Doppler spreads and level crossing rate. According to estimation outcomes, the V2 V channel characteristics for urban areas in Chinese big city were different from the previous measured results under similar scenarios in Europe. Delay spread and level crossing rate in this study can provide significant references to design the wireless communication system for vehicle-to-vehicle channel.

摘要：Vehicles enlisted with computing, sensing and communicating devices can create vehicular networks, a subset of cooperative systems in heterogeneous environments, aiming at improving safety and entertainment in traffic. In vehicular networks, a vehicle＇s identity is associated to its owner＇s identity as a unique linkage. Therefore, it is of importance to protect privacy of vehicles from being possibly tracked. Obviously, the privacy protection must be scalable because of the high mobility and large population of vehicles. In this work, we take a non-trivial step towards protecting privacy of vehicles. As privacy draws public concerns, we firstly present privacy implications of operational challenges from the public policy perspective. Additionally, we envision vehicular networks as geographically partitioned subnetworks （cells）. Each subnetwork maintains a list of pseudonyms. Each pseudonym includes the cell＇s geographic id and a random number as host id. Before starting communication, vehicles need to request a pseudonym on demand from pseudonym server. In order to improve utilization of pseudonyms, we address a stochastic model with time-varying arrival and departure rates. Our main contribution includes： 1） proposing a scalable and effective algorithm to protect privacy; 2） providing analytical results of probability, variance and expected number of requests on pseudonym servers. The empirical results confirm the accuracy of our analytical predictions.

摘要：为了在保证结果精度的情况下加快运算速度,改进了矩阵补全的代表性算法——奇异值门限(SVT)算法.首先对于输入矩阵进行规整化处理,之后在每一步的迭代中使用奇异值分解算法对矩阵进行恢复.由于每个迭代步中奇异值分解的计算量很大,文中借鉴随机矩阵奇异值分解算法,提出使用块克雷洛夫迭代近似奇异值分解算法和子空间复用技术的快速SVT算法.使用彩色图像和电影评分矩阵对算法进行实验的结果表明,快速SVT算法在不影响图像恢复和评分数据预测效果的同时显著地缩短了计算时间;在图像恢复和电影评分预测的实验中,分别取得了高达7.1倍和3.2倍的加速比.

摘要：对柔性多体系统计算建模的研究现状和近期进展进行了总结．重点讨论了柔性多体动力学的以下内容:柔性构件的建模,约束建模,求解技术,控制策略,耦合问题,设计和实验的研究．对柔性多体系统建模的浮动坐标系,转动坐标系和惯性系等3种坐标系的特点进行了对比．指出了未来的研究方向,包括柔性多体系统的新的应用,如微观力学系统和超微观力学系统等;提高这些模型的计算精度和效率的技巧和策略;以及可以用于改善柔性多体系统的工具．本综述文章引用了877篇参考文献．

摘要：The relation between commodities and consumers is directly related to the transactional relationship between kids and their interaction with the *** paper aims to critique how female representation through Barbie Dolls in popular culture shapes female *** and consumption of Barbie dolls in India became a way of socializing mechanism to educate young Indian girls on the concept of beauty.A notion of beauty is attached to blue eyes,skinny waist,and fair skin giving rise to“American Exceptionalism”(Madsen,2009,p.14),where the model nation conceptualizes itself though national identity where perceiver compels to transform themselves to“fit in.”I want to study the relationship between body,embodiment,and technology through the representation of Barbie dolls in media and the political orientation of its stereotypical and ethnocentric identity formation giving rise to cultural production.I want to find out how gendered representations produces itself on television and the internet,which continue to make“coding of the body”(Barker et al.,2005,p.5)through evidence of Barbie’s aesthetic *** allows Indian girls to play with their senses of self in a way that plays a crucial role in identity *** Indian girls can see and also read themselves as fixed objects within a closed system of *** the theoretical concept of“American Exceptionalism”,the paper will analyze how social identification conceived through the media *** to the mass production and mass consumption of Barbie Dolls is also the notion of developing the culture of promotion and advertising that supports the selling *** financial capital and the cost of Barbie Dolls divides the consumption market as possessing a Barbie Doll becomes a symbol of elitism in Indian households.

摘要：该文围绕经济赤贫、社会孤立和社会控制状态以及个体特征等对不同人群HIV高危行为的影响因素,以及高危行为的具体表现,设计问卷指标;对昆明市城镇150个HIV感染者、吸毒人群、流动人口和常住居民进行深入问卷调查,分析结果显示了不同人群HIV高危行为的差异,并对此作出了解释。