W波段模拟通信研究

依据图像质量等级与图像信噪比之间的关系,对调频制图像传输系统的性能进行了预测,并对W波段模拟图像传输技术进行了研究,介绍了系统方案、系统关键技术和系统实验结果,并对系统中采用的毫米波振荡器、混频器、双工器、天线等毫米波元部件的电性能指标进行了描述。该系统成本低、工作稳定、可靠,在8 km距离上,系统图像传输质量优于4.5级。     

语义联系与词汇教学

有语义联系的词汇呈现方式是基于认知心理学理论的词汇教学策略。本文首先简要阐述该呈现方式的基本主张、理论依据及其积极意义,然后笔者提出几点反思:以同义词和语义场词汇为例分析该呈现方式可能出现的问题,并从心理学语言学角度阐述词汇输入和吸收的关系来考察该方法的可行性和有效性。     

碳税制度下企业产品升级及信息披露策略研究

在实行碳税制度的背景下,本文构建了包含两家制造商的双寡头模型,以其中一家制造商是否投资产品升级减排作为关键信息,分别研究信息不公开(模型1)和信息公开(模型2)时两家制造商的均衡定价与最优利润以及制造商产品升级的条件,并且进一步研究当制造商同时掌握技术决策权和信息披露权时选择四种不同决策方案的条件。理论结果表明,如果升级后单位实际生产成本变大,制造商选择不升级且不公开;如果升级后单位实际成本变小,当升级后利润增值大于固定成本投入时,制造商选择升级并不公开,反之,选择不升级并公开。无论升级前后单位实际成本大小关系如何,制造商都不会选择升级且公开信息。数值试验部分表明,当制造商同时掌握技术选择权和信息披露权时,碳税是驱动制造商进行升级减排的主要因素,随着碳税的提高,制造商会依次从不升级不公开,不升级公开到升级不公开做决策。当不升级的概率越大时,制造商会在较低的碳税点越早开始升级;当减排努力越大时,制造商会在较高的碳税点才开始升级。     

论技术创新的社会系统效应与本质

技术创新是目前企业谋求生存发展的根本出路.本文从企业的社会环境系统、文化价值观念、社会建制、社会动力系统、社会化过程、社会运行机制等方面,较为深入地揭示了技术创新的社会系统诸要素的综合效应、本质和规律,提出了许多独特见解,并同时阐示了我国企业在技术创新上所存在的诸问题及其解决方案.因此我们对技术创新的研究具有着重大的理论价值和现实意义.     

A New Pearson-Type QMLE for Conditionally Heteroscedastic Models

This article proposes a novel Pearson-type quasi-maximum likelihood estimator (QMLE) of GARCH(p, q) models. Unlike the existing Gaussian QMLE, Laplacian QMLE, generalized non-Gaussian QMLE, or LAD estimator, our Pearsonian QMLE (PQMLE) captures not just the heavy-tailed but also the skewed innovations. Under strict stationarity and some weak moment conditions, the strong consistency and asymptotic normality of the PQMLE are obtained. With no further efforts, the PQMLE can be applied to other conditionally heteroscedastic models. A simulation study is carried out to assess the performance of the PQMLE. Two applications to four major stock indexes and two exchange rates further highlight the importance of our new method. Heavy-tailed and skewed innovations are often observed together in practice, and the PQMLE now gives us a systematic way to capture these two coexisting features.     

互联网超文本链接的知识论后果

随着互联网的勃兴 ,超文本在人类知识活动中的重要性正日益凸显。以非线性链接、跳跃、文本间性、开放性、超媒体等为核心特征的网络超文本 ,对人类知识活动有着多方面的影响。超文本的凸显 ,不仅产生了虚拟认识这一全新的认识形式 ,而且对提高认识效率、拓展知识空间、开阔认识视野 ,以及跨学科研究等也有实质性的影响。但是 ,超文本链接亦有可能造成认识方向感丧失、主体性消解、记忆力下降 ,以及知识平面化和碎片化、思维架构弱化等负面效应     

“帐外帐”的税务检查

近年来,从税务检查部门查处的涉税违法案件的总体情况看,设置“帐外帐”、搞帐外经营已成为偷税的主要形式之一。如何在实践中不断总结“帐外帐”偷税的违法规律,研究“帐外帐”的税务检查方法,积极寻求治理对策成为税务检查部门的当务之急。     

Assessing the Precision of Turning Point Estimates in Polynomial Regression Functions

Researchers often report point estimates of turning point(s) obtained in polynomial regression models but rarely assess the precision of these estimates. We discuss three methods to assess the precision of such turning point estimates. The first is the delta method that leads to a normal approximation of the distribution of the turning point estimator. The second method uses the exact distribution of the turning point estimator of quadratic regression functions. The third method relies on Markov chain Monte Carlo methods to provide a finite sample approximation of the exact distribution of the turning point estimator. We argue that the delta method may lead to misleading inference and that the other two methods are more reliable. We compare the three methods using two data sets from the environmental Kuznets curve literature, where the presence and location of a turning point in the income-pollution relationship is the focus of much empirical work.     

Competing Failure Risk Analysis Using Evidence Theory

Safety systems are important components of high-consequence systems that are intended to prevent the unintended operation of the system and thus the potentially significant negative consequences that could result from such an operation. This presentation investigates and illustrates formal procedures for assessing the uncertainty in the probability that a safety system will fail to operate as intended in an accident environment. Probability theory and evidence theory are introduced as possible mathematical structures for the representation of the epistemic uncertainty associated with the performance of safety systems, and a representation of this type is illustrated with a hypothetical safety system involving one weak link and one strong link that is exposed to a high temperature fire environment. Topics considered include (1) the nature of diffuse uncertainty information involving a system and its environment, (2) the conversion of diffuse uncertainty information into the mathematical structures associated with probability theory and evidence theory, and (3) the propagation of these uncertainty structures through a model for a safety system to obtain representations in the context of probability theory and evidence theory of the uncertainty in the probability that the safety system will fail to operate as intended. The results suggest that evidence theory provides a potentially valuable representational tool for the display of the implications of significant epistemic uncertainty in inputs to complex analyses.