汽车柴油发动机可靠性试验的重要性和必要性

文章针对当前汽车柴油发动机产品在可靠性方面存在的主要问题,结合国家试验标准,通过列举某台国产汽车柴油机可靠性试验中出现的故障情况及排除措施,纠正此类可靠性试验保养操作中的常见误区,阐明进行汽车柴油机可靠性试验的重要性和必要性。     

关于考查课教育及成绩评定的思考与探索

剖析了考查课教育及成绩评定现状中的弊端,从纳什均衡的角度分析了要达到最优状态必需进行考查课教育与成绩评定改革。关于考查课教育及成绩评定,文章做了详细地思考和探讨,指出通过研发基于层次分析法的考查课程成绩管理系统来完成成绩的评定,给出的评定准则科学客观公正。该网站的建立实现了考查课程成绩评定的自动化、督促了教师对考查课教育的改革、最大限度的维护了学校开设考查课程的初衷。     

不同需求规律下的航材安全库存量研究

安全库存是有效处理航材供应过程中遇到的各种突发情况的重要保证,针对航材需求量波动变化的实际情况,对航材安全库存量开展了深入研究。首先,研究了不同航材类型及其安全库存量需求的特点;其次,分析了航材需求分布类型,进而研究了不同需求量变化规律的确定方法;然后,研究建立了不同需求量规律下的航材安全库存量的确定方法;最后,通过算例验证了方法的可行性和有效性,为飞机制造商和航空公司的航材管理提供了有效方法和切实指导。     

Restricted forecasting with VAR models: An analysis of a test for joint compatibility between restrictions and forecasts

A restricted forecasting compatibility test for Vector Autoregressive Error Correction models is analyzed in this work. It is shown that a variance–covariance matrix associated with the restrictions can be used to cancel out model dynamics and interactions between restrictions. This allows us to interpret the joint compatibility test as a composition of the corresponding single restriction compatibility tests. These tests are useful for appreciating the contribution of each and every restriction to the joint compatibility between the whole set of restrictions and the unrestricted forecasts. An estimated process adjustment for the test is derived and the resulting feasible joint compatibility test turns out to have better performance than the original one. An empirical illustration of the usefulness of the proposed test makes use of Mexican macroeconomic data and the targets proposed by the Mexican Government for the year 2003.     

光缆自动化监测系统

介绍了远程光纤监测系统(RFTS)的结构、测试方法及其与电信管理网(TMN)的结合情况,并列举出一些典型的RFTS系统以阐明其应用和发展趋势。同时,还讨论了影响光时域反射仪(OTDR)测试精度的要素和消除测试误差通常采用的对策。     

国际油价波动对中国宏观经济影响的实证分析

运用格兰杰因果检验结合脉冲响应函数,来实证分析国际油价波动分别对中国宏观经济的五个变量——消费(C)、投资(I)、政府支出(G)、出口(EX)、进口(IM)的影响;同时,针对油价波动对国民经济各方面产生的影响,提出了一些建议和对策。     

Three Corrected Score Tests for Generalized Linear Models with Dispersion Covariates

We develop three corrected score tests for generalized linear models with dispersion covariates, thus generalizing the results of Cordeiro , Ferrari and Paula (1993) and Cribari-Neto and Ferrari (1995) . We present, in matrix notation, general formulae for the coefficients which define the corrected statistics. The formulae only require simple operations on matrices and can be used to obtain analytically closed-form corrections for score test statistics in a variety of special generalized linear models with dispersion covariates. They also have advantages for numerical purposes since our formulae are readily computable using a language supporting numerical linear algebra. Two examples, namely, iid sampling without covariates on the mean or dispersion parameter oand one-way classification models, are given. We also present some simulations where the three corrected tests perform better than the usual score test, the likelihood ratio test and its Bartlett corrected version. Finally, we present a numerical example for a data set discussed by Simonoff and Tsai (1994) .     

Factor pricing of cryptocurrencies

In this paper, we study the cryptocurrency pricing factors. We review the literatures which state that the cryptocurrency market is weakly efficient. We use the Fama–MacBeth method to investigate the pricing factors. The classical equity-based risk factors including size, momentum, and value to growth from the Fama–French three factor model are studied. We use crypto-unique coin-to-token as a proxy for value-to-growth. For volatility risk factor category, we investigate realized volatility, skewness and jump. We also investigate liquidity factors including bid–ask, volume growth and Roll’s measure. The macro factors are found not to be an explanatory factor. The attention factor works sometimes. The factor model constructed by the significant factors explain most of the excess return of cryptocurrencies.     

WICKEDNESS IN SOCIAL CHOICE

In an article from 1973, Rittel and Webber distinguished between ‘tame’ or ‘benign’ problems on the one hand and ‘wicked’ problems on the other. The authors argued that wicked problems occur in nearly all public policy issues. Since different groups adhere to different value-sets, solutions can only be expressed as better or worse. By no means can they be viewed as definitive or objective. In this paper we consider, from this very angle, the theory of social choice which is about the aggregation of individual preferences with the aim to derive a consistent social preference. We show that collective choice offers wicked problems of various types which differ in their degree of severity. We hereby concentrate on welfare functions and voting schemes of different kinds and discuss these in the light of various criteria such as Arrow's independence condition, Condorcet consistency, monotonicity, manipulability, and other properties.