Perceived risk and trust associated with purchasing at electronic marketplaces

Understanding consumer behaviour is of vital importance to consumer-oriented e-business models today. In this paper, we study the relationships between consumer perceptions of risk and trust and the attitude towards purchasing at a consumer-to-consumer electronic marketplace (EM). Typical for EM settings is that consumer behaviour is subject to perceptions of the selling party as well as of the institutional structures of the intermediary that is operating the EM. Building upon the well-established literature of trust, we consider the concepts of intermediary trust and seller trust. We extend this categorisation by introducing the concepts of intermediary risk and seller risk. We developed measurement instruments for intermediary risk and seller risk. All measurement scales have acceptable alphas and are unidimensional. An empirical study is conducted to explore the relationships between the risk and trust types and consumer purchase attitude. The results reveal significant, direct effects of seller trust and seller risk. Second-order effects of intermediary trust and intermediary risk are investigated and reported. The paper concludes with general observations and recommendations for research and practice.     

新型超微晶软磁合金FePCCuMoSi微观结构缺陷的正电子湮没研究

用正电子湮没方法研究了新型超微晶软磁合金的微观结构缺陷，样品选用的是在不同温度下退火的Ｆｅ８１Ｐ１２Ｃ３Ｃｕ１Ｍｏ０．５Ｓｉ２．５合金，结果表明，合金的微观结构构陷大小，密度随退火温度有规律地变化，这种现象可能与非晶的晶化过程有关。     

硬件握手双向选通型串行通信共享器的设计

本文介绍了ＩＢＭ－ＰＣ系列计算机通过ＲＳ－２３２Ｃ串行口与多个单片微机组成的分布式系统中一种可双向选通串行通信共享器的设计方法。给出通信共享器的设计电路；并对电路工作原理进行了详细剖析。     

输气管道天然气连续取样器的研制及应用

文章针对国内管输天然气气质分析工作中取样环节所存在的问题，结合国外技术发展趋势，全面地介绍了输气管道天然气连续取样器的研制过程。实践证明，该装置较好地解决了天然气密度值偏差问题，满足管输天然气全分析的要求，同时，该装置的推广应用将会提高天然气的计量准确度。     

端羟基聚二甲基硅氧烯改性环氧树脂

用羟基封端的聚二甲基硅氧烷改性环氧树脂，得到具有两相结构的改性树脂，其耐热性明显提高．环氧树脂／有机硅（20／80）共混物涂层有很低的表面能，主要的机械性能则变化不大，可作为一种疏水性防护徐层．     

Optimal solutions for a dynamic bandwidth allocation scheme in high-speed networks

In this paper, we investigate the problem of determining the optimal bandwidth allocation for a Dynamic Bandwidth Allocation Scheme (DBAS). The objective is to minimize the total amount of bandwidth required to satisfy the Quality of Service (QoS) requirements of all traffic streams. It is shown that when the performance functions satisfy a certain number of conditions, there exists a unique optimal bandwidth allocation such that, for each traffic stream, either its QoS is just satisfied or its QoS is over-satisfied and it is allocated zero bandwidth. Such an allocation is said to be efficient. It is also shown that there exists a unique efficient allocation in the entire feasible region. An iterative algorithm is developed to compute the efficient allocation employing its special properties. Numerical examples are presented to demonstrate how the algorithm works. Future extensions of this work are also discussed.Partially supported by NSERC of Canada through grants OGP14020 and STRIN-200.     

X波段及DBS接收用PHEMT单片低噪声放大器

报道了X波段及DBS接收用单片低噪声放大器的研制结果。利用CAD软件对单片电路进行优化设计，设计工作包括MBE材料、PHEMT器件和单片电路三部分。在研制过程中，开展了关键工艺的专题研究。研究结果为：单级单片放大器在10：5－11．6GHz范围内，NF≤1．82dB，G≥7.72dB；在11．7－12．2GHz范围内，NF≤1．80dB，G≥6．8dB；双级放大器在10．4－11．1GHz范围内，NF≤1．96dB，G≥15．3dB，最低噪声系数为1．63dB，最高增益为16．07dB。