微波锁相环中取样鉴相器

<正> 泰国是继新加坡、台湾、香港、韩国等亚洲新兴工业国家和地区之后,经济发展较快的国家之一。近十多年间,泰国不断扩大对外开放,企业随之走上了国际竞争的舞台,经济由此登上了新的台阶。泰国企业开拓国际经营及强化市场竞争有许多成功之经验,很值得我们在进一步发展外向型经济中借鉴。     

空基通信抗干扰技术的初步探讨

本文概述了国外军事通信抗干扰技术,通信对抗技术的概况。分析了跟踪式干扰能力的一些限制因素,预测了空基通信抗干扰技术的发展趋势。介绍了航空兵地空战术通信系统的组成与特点。指出DS/FH混合体制应为地空战术通信系统优选的抗干扰体制,并分析了DS/FH混合体制的各项关键技术。     

Quality competition,welfare, and regulation

In this paper, we study the supply of quality in imperfectly competitive markets, and explore the role of regulation in markets where firms may use both quality and price to compete for customers. In a model where firms first choose qualities and then prices, we find that quality decisions have strategic effects: firms react to quality disadvantages by price reductions. Because of this strategic effect, firms do not have the correct incentive to set socially efficient quality levels. Price and quality competition results in a socially suboptimal quality level. Efficiency can be restored by lump-sum transfers and price regulatory policies. Simple price regulation may result in lower price and higher quality.We thank Nicholas Economides, Randall Ellis, Thomas McGuire, Michael Riordan, and Monika Schnitzer for discussing various issues in this research with us. We are also grateful to a referee for helpful comments and suggestions. The first author acknowledges support from the Management Science Group, Department of Veterans Affairs at Bedford, Massachusetts. The ideas here do not represent those of the Department of Veterans Affairs.     

Ⅰ、Ⅱ、Ⅲ类零价最小剩余相位误差环

本文证明在注入锁定情况下,压控注锁振荡器实质上是压控可变相移振荡器(VCPSO)。分析了由鉴频器(FD)、鉴相器(PD),以及FD加PD同VCPSO构成的三种环路,并分别给出了等效框图,及相应的闭环相位传递函数。为了与一般锁相环路相区别,分别称之为Ⅰ、Ⅱ、Ⅲ类零阶最小剩余相位误差环。     

一类新的模式识别联想神经网络

本文提出一类可用于模式识别的联想神经网络的综合方法,这类网络结构不受对称联接的限制,网络保证了要求的M类模式的稳定形成,且网络的容量远远超过Hopfield的联想神经网络,网络渐近稳定平衡点的吸引特性使受噪声污染的模式能得以正确恢复,体现了神经网络的非线性滤波性质。文中给出了综合一个这类联想网络计算机模拟以及模式识别的例子。     

论行业组织在关贸总协定体制中的作用

我国即将恢复在关贸总协定中的席位。作为关贸总协定的一个缔约方,我国就可以按其所确立的利益机制获得经贸利益。然而,“可以”获得利益不等于就能坐享利益。关贸总协定所确立的利益机制是纷繁复杂的,它只是保证了利益的存在,而各缔约方要想实际享受到利益,还必须主动地去努力获取。以往数十年的情况表明,有些缔约方充分享受到了关贸总协定所确立的利益(如日本、南朝鲜等),有些则没有(如印度等)。