Evaluation of performance enhancing proxies in internet over satellite

Performance enhancing proxies (PEPs) are widely used to improve the performance of TCP over high delay‐bandwidth product links and links with high error probability. In this paper we analyse the performance of using TCP connection splitting in combination with web caching via traces obtained from a commercial satellite system. We examine the resulting performance gain under different scenarios, including the effect of caching, congestion, random loss and file sizes. We show, via analysing our measurements, that the performance gain from using splitting is highly sensitive to random losses and the number of simultaneous connections, and that such sensitivity is alleviated by caching. On the other hand, the use of a splitting proxy enhances the value of web caching in that cache hits result in much more significant performance improvement over cache misses when TCP splitting is used. We also compare the performance of using different versions of HTTP in such a system. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of stimulus emotionality and sentence generation on memory for words in adults with unilateral brain damage.

Does sentence generation and/or stimulus emotionality enhance verbal memory in patients with neurological impairment? This question was addressed by testing 40 patients with unilateral stroke (20 with left-brain and 20 with right-brain damage) and 20 healthy control participants for recall and recognition of 48 target words. During encoding, emotional and nonemotional words were either presented in sentences (read condition) or used to form sentences (generate condition). Both word emotionality and generative processing improved memory performance in all groups. The authors suggest that a similar influence (i.e., cognitive activation) underlies both of these memory-enhancing effects, although the putative origins of the 2 effects are quite different. Neuropsychological underpinnings and clinical implications of these phenomena are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

在苯基羧甲基亚砜体系中高氯酸铒对高氯酸铽的荧光增强效应

合成了不同摩尔比的苯基羧甲基亚砜高氯酸铽、铒异核配合物,对配合物进行了组成分析,确定了配合物组成为Tb1-xErxL2ClO4·2H2O(x=0.000～0.200,L=C6H5SOCH2COO-)。通过IR光谱的测定以及摩尔电导推测了配位情况。荧光光谱实验表明:当x=0.001～0.010时铒对铽的荧光均产生敏化增强效应,当x=0.001时敏化强度最大,可使Tb3+荧光强度增加142%。     

新型无石棉摩阻材料用增强纤维研究进展

综述了近几年无石棉摩阻材料用增强纤维研究进展,介绍了摩阻材料在使用过程中的摩擦磨损机制,重点介绍了新型无石棉摩阻材料用增强纤维的研究成果。     

新型聚硅铝铁絮凝剂强化处理低温低浊水

以硅酸钠、硫酸、硫酸铝和三氯化铁为原料制备了聚硅铝铁复合絮凝剂，对低温低浊水进行处理研究，并与硫酸铝、PAC进行了对比。结果表明，聚硅铝铁复合絮凝荆对低温低浊水有较好的处理效果，投加量为4mg／L时，出水浊度在0．5NTU以下。     

交叉缩放椭圆强化换热管内流动和传热性能的数值研究

以交叉缩放椭圆强化换热管为几何模型,对管内的传热和流动进行数值模拟,计算结果表明,过渡段流场不同于直管段,纵向涡流较大,湍流强度和湍动能都较大,过渡段强化传热效果明显好于直管段,但阻力也增加了;并且发现随着椭圆长轴与短轴之比的增加,换热增强,为交叉缩放椭圆强化换热管在换热领域的实际应用提供了理论依据.     

考虑结算规则的多尺度市场耦合下梯级水电站中期运行风险分析方法

因为径流时空分布不均和不确定性,水电、火电为主的电力市场之间存在极大的不同,如何评估梯级水电参与电力交易风险是亟待解决的问题。该文结合西南某水电居主导地位的电力市场交易规则,构建了耦合月度交易和日前增量交易的梯级水电站参与市场交易的风险分析方法:采用Copula-Monte Carlo方法生成日径流和日前增量交易出清电价的组合场景,利用增强精英保留策略遗传算法计算所有场景的发电收益,获得给定置信水平下相应的条件风险价值。提出的方法综合考虑了径流、电价的不确定性,也计及了结算规则中各交易品种结算顺序和偏差考核标准,能直观求解收益风险值,过程简单、物理意义明确。以某电网梯级水电参与电力市场的实际资料为例,进行结果的仿真分析,结果表明所提方法可方便地求解交易组合风险价值,与单独考虑电价和径流相比能更合理的评估收益风险价值。     

管内扭带传热与流动阻力的实验研究

为了研究管内强化换热技术,对3根不同结构参数的扭带插入光管的换热特性和流体动力学特性进行了实验研究.以空气为工质,Re在8 000～100 000之间,管外被水冷却.在大量实验数据的基础上,用多元线性回归法得到了具有较高精度的扭带管的传热系数和摩擦系数的统计关联式,分析了扭带管的传热与流阻性能,为换热器的设计及改造提供了理论依据.     

Privacy leakage on the Web: Diffusion and countermeasures

Protecting privacy on the Web is becoming increasingly complicated because of the considerable amount of personal and sensitive information left by users in many locations during their Web browsing and the silent actions of third party sites that collect data, aggregate information and build personal profiles of Internet users in order to provide free and personalized services. On the other hand, most of people are unaware that their information may be collected online, and that, after their aggregation from multiple sources, could be used for secondary purposes, such as linked to allow identification, without user’s notice.