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31.
Steffen Kozempel  Klaus Tauer 《Polymer》2005,46(4):1169-1179
An online multi-angle laser light scattering study of ab initio surfactant-free styrene emulsion polymerization reveals unexpected results regarding the development of the dispersity during the whole reaction starting from mixing styrene and water at reaction temperature. The experimentally observed change in the dispersity, which is an indirect measure of the average characteristic size of the colloidal objects, allows the identification of three characteristic intervals. During interval A the equilibration of styrene in water is characterized by the formation of styrene domains, which increase in number and size until an equilibrium state is reached. This means that there is virtually no homogeneous/molecular styrene in water solution but rather nanodroplets of about 200 nm in diameter (assuming spherical shape) are formed. During interval B, after initiation of the polymerization and particle formation, the dispersity increases again as the average size decreases and the number of scattering objects increases. The polymer particles suck up the monomer from the monomer nanodroplets, which leads to the disappearance of the nanodroplets and to a decrease in the average size. During interval C the average size increases again due to the predominantly growth of the polystyrene particles.  相似文献   
32.
Consumer complaints on online social network quickly become online groups complaints through many people’s aggregation and looking on, interaction and word-of-mouth communication. Therefore, assessing and managing online complain influence has become a new problem for enterprise to listen to and manage online group complaints. This paper analyzed the complaint information feature of consumer group on online social network, from three-dimensional perspective of complaint text’s quality, transmission timeliness and user interaction degree. We built the influence measure model of online complaint theme based on entropy weight model by monitoring and analyzing real-time the static and dynamic properties of complaint information, explored the measure method of complaint theme influence, employed empirical method to verify the validity and provided scientific decision-making tools and methods for enterprise listening to and managing online group complains.  相似文献   
33.
针对目前端到端可用带宽预测方面研究工作较少的现状,提出一种基于核主成分分析KPCA(Kernel Principle Component Analysis)和最小二乘支持向量机LSSVM(Least Squares Support Vector Machine)的可用带宽在线预测算法ABOP。在采集网络状态样本数据并对其进行相空间重构的基础上,采用KPCA对数据进行降维降噪处理,最后基于LSSVM对可用带宽进行在线预测。为减小计算开销,提出一种递推计算的方法加快模型更新速度,并采用粒子群优化算法对模型参数进行多步更新,确保了在线预测的时效性。仿真表明,提出的ABOP算法具有较高的预测精度和较快的预测速度,能够满足可用带宽在线预测的要求。  相似文献   
34.
介绍生物制药厂在线环境监测系统检测点的选取,系统设备选型和系统功能,系统通过一年多时间运行,证明设计合理,功能齐全,满足GMP要求,系统安全、可靠。  相似文献   
35.
Notwithstanding many years of progress, visual tracking is still a difficult but important problem. Since most top-performing tracking methods have their strengths and weaknesses and are suited for handling only a certain type of variation, one of the next challenges is to integrate all these methods and address the problem of long-term persistent tracking in ever-changing environments. Towards this goal, we consider visual tracking in a novel weakly supervised learning scenario where (possibly noisy) labels but no ground truth are provided by multiple imperfect oracles (i.e., different trackers). These trackers naturally have intrinsic diversity due to their different design strategies, and we propose a probabilistic method to simultaneously infer the most likely object position by considering the outputs of all trackers, and estimate the accuracy of each tracker. An online evaluation strategy of trackers and a heuristic training data selection scheme are adopted to make the inference more effective and efficient. Consequently, the proposed method can avoid the pitfalls of purely single tracking methods and get reliably labeled samples to incrementally update each tracker (if it is an appearance-adaptive tracker) to capture the appearance changes. Extensive experiments on challenging video sequences demonstrate the robustness and effectiveness of the proposed method.  相似文献   
36.
37.
As research on virtual worlds gains increasing attention in educational, commercial, and military domains, a consideration of how player populations are ‘reassembled’ through social scientific data is a timely matter for communication scholars. This paper describes a large‐scale study of virtual worlds in which participants were recruited at public gaming events, as opposed to through online means, and explores the dynamic relationships between players and contexts of play that this approach makes visible. Challenging conventional approaches to quantitatively driven virtual worlds research, which categorizes players based on their involvement in an online game at a particular point in time, this account demonstrates how players' networked gaming activities are contingent on who they are playing with, where, and when.  相似文献   
38.
E-life--家居生活视频网主要是在和用户充分交流的基础上,实现资源共享,共同建设属于普通大众的现代家居生活视频网站。其立足于现代家居生活,通过对现代家居生活类视频的集合,从而方便用户的检索、浏览和下载。  相似文献   
39.
One-sided auctions are used for market clearing in the spot markets for perishable goods because production cost in spot markets is already “sunk.” Moreover, the promptness and simplicity of one-sided auctions are beneficial for trading in perishable goods. However, sellers cannot participate in the price-making process in these auctions. A standard double auction market collects bids from traders and matches the higher bids of buyers and lower bids of sellers to find the most efficient allocation, assuming that the value of unsold items remains unchanged. Nevertheless, in the market for perishable goods, sellers suffer a loss when they fail to sell their goods, because their salvage values are lost when the goods perish. To solve this problem, we investigate the suitable design of an online double auction for perishable goods, where bids arrive dynamically with their time limits. Our market mechanism aims at improving the profitability of traders by reducing trade failures in the face of uncertainty of incoming/departing bids. We develop a heuristic market mechanism with an allocation policy that prioritizes bids of traders based on their time-criticality, and evaluate its performance experimentally using multi-agent simulation. We find out that our market mechanism realizes efficient and fair allocations among traders with approximately truthful behavior in different market situations.  相似文献   
40.
Users are the most critical strategic resource of any online social networking service (SNS). This paper offers strategic recommendations for SNS providers based on an empirical study exploring why users switch from a primary SNS to others. We first identify important characteristics that combine to distinguish SNSs from conventional information systems, then develop a “cyber migration” research model that includes push, pull and mooring factors which influence user intention to switch from one SNS to another. Findings from a field survey of 180 users reveal four significant factors that promote switching: dissatisfaction with socialization support, dissatisfaction with entertainment value, continuity cost, and peer influence. Strategies grounded in these factors are suggested for SNS providers to better attract and retain users.  相似文献   
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