Hypothesis testing and parameter estimation based onM-statistics ink samples with unequal variances

Summary Ink samples with unequal variances,M-tests for homogeneity ofk location parameters are proposed. The asymptoticχ ²-distributions of the test statistics and the robustness of the tests are investigated. NextM-estimators (ME’s) of parameters are discussed. Furthermore positive-part shrinkage versions (PSME’s) of theM-estimators for the location parameters are considered along with modified James-Stein estimation rule. In asymptotic distributional risks based on a special feasible loss, it is shown that the PSME’s dominate the ME’s, and preliminary test and shrinkageM-versions fork≧4.     

A non-local perspective on the power properties of the CUSUM and CUSUM of squares tests for structural change

We consider the power properties of the CUSUM and CUSUM of squares (CUSQ) tests in the presence of a one-time change in the parameters of a linear regression model. A result due to Ploberger and Krämer [1990. The local power of the cusum and cusum of squares tests. Econometric Theory 6, 335–347.] is that the CUSQ test has only trivial asymptotic local power in this case, while the CUSUM test has non-trivial local asymptotic power unless the change is orthogonal to the mean regressor. The main theme of the paper is that such conclusions obtained from a local asymptotic framework are not reliable guides to what happens in finite samples. The approach we take is to derive expansions of the test statistics that retain terms related to the magnitude of the change under the alternative hypothesis. This enables us to analyze what happens for non-local to zero breaks. Our theoretical results are able to explain how the power function of the tests can be drastically different depending on whether one deals with a static regression with uncorrelated errors, a static regression with correlated errors, a dynamic regression with lagged dependent variables, or whether a correction for non-normality is applied in the case of the CUSQ. We discuss in which cases the tests are subject to a non-monotonic power function that goes to zero as the magnitude of the change increases, and uncover some curious properties. All theoretical results are verified to yield good guides to the finite sample power through simulation experiments. We finally highlight the practical importance of our results.     

电源传输效率与负载最大功率的探讨

文章指出,当电源一定时,电路中负载消耗的电功率与负载大小有关,负载电阻与电源内阻相等时电路为匹配状态。电路中负载消耗电功率与电源传输效率之间是矛盾对立的关系,它们在电力线路与电子电路中有着不同的应用。     

基于智能功率模块的电法发送机的设计

文章通过具体的发送机设计示例介绍了智能功率模块(简称IPM)的器件结构、开关特性和应用接口,并讨论了如何将其应用到电法勘探发送机中。     

南方电网区域内输煤输电经济性比较研究

近年来随着环保要求的提升、发电煤耗的降低以及特高压直流输电技术的发展等各种因素的变化,输电输煤比较研究的基础逐渐改变。文章对南方电网区域内煤炭资源两种输送方式进行经济性比较,力求为煤炭资源输送方式的合理配置和煤电优化布局提供参考依据,以取得良好的社会经济和环境等综合效益。     

矿井供电系统节能与优化探讨

煤矿企业生产环节多,过程复杂,电能消耗巨大,是我国重点耗能行业之一,其电能成本占到了煤矿生产总成本的2/3甚至更多,矿井节能已成为煤炭行业亟待解决的重要课题,实施矿井节能管理和节能改造势在必行,文章结合作者自身实践,对矿井供电系统的节能和优化提出了见解。     

浅谈电力公司的营销策略及其重要性

营销策略是公司以顾客的需求为出发点,根据所积累的经验获得顾客的需求量以及购买力的有关信息,并且有计划地组织各种经营活动,再通过协调一致的产品策略、价格策略、渠道策略和促销策略等,为顾客提供满意的商品和服务而实现公司目标的一个过程。其重要性对任何以市场为导向的企业都不言而喻,文章着重对电力公司的营销策略及其重要性进行探讨。     

农村集体建设用地流转收益分配研究--基于公平与效率视角

收益分配是农村集体建设用地流转的核心,关系到城乡统一建设用地市场建立的成败。在探讨国内农村集体建设用地流转增值收益分配模式的基础上,分别从社会、区域公平的角度和城镇化、工业化效率角度分析流转增值收益分配。兼顾公平与效率的原则,统筹协调集体经济组织与集体成员之间、规划限制下土地权利人之间、城乡居民之间、发达地区与基本农田保护区之间的利益关系,提出以市场的方式形成流转收益,以税收方式进行收益调节,再通过农业补贴实现利益均衡,以完善集体建设用地流转收益的分配机制。     

The effect of transaction costs, payment terms and power on the level of raw materials inventories

This paper proposes and tests an explanation for the level of raw materials inventories based on transaction cost economics theory and the role of power in a supply chain. According to this explanation, raw materials inventories are larger the higher a company's transaction costs and the lower its storage-related production and management costs. Factors that affect these costs are the company's vulnerability to opportunism, whether the input becomes more or less costly to store and manage as it moves through the supply chain, payment terms and the company's power in relation to its supplier. This explanation for the level of raw materials inventories was tested on a large sample of customer industries matched to their main supplier industries. Consistent with this theory, the empirical results show that companies hold larger raw materials inventories the more money their suppliers spend on research and development and the less important the customers are to their suppliers. These results are important because they indicate companies must consider a wider range of factors than previously thought necessary when establishing inventory policy.     

浅谈配电工程中变压器的选择及安装

进入21世纪以来,我国电力系统的建设工作进入了一个全新的时期。由于我国现有的配电系统具有覆盖范围广、运行负荷大等特点,同时受到运行环境以及各种自然、人为因素的影响,发生电气故障的现象极为普遍,并且可能导致配电系统在运行中出现较大的安全隐患。因此,在配电工程的建设中,一定要注意对于变压器的选择与安装,这样才能保证配电系统的安全、稳定、高效运行。     

点检定修制管理在新建电厂的应用探讨

文章针对火力发电厂设备检修管理现状,介绍了点检定修制的基础理论,并就点检定修制在湖南华电长沙发电有限公司具体的实施情况和技术方面的推广应用进行了详细的论述,指出了新建电厂实行点检定修的必要性。     

会计信息披露的效率与公平问题——基于会计信息产权和会计外部化的思考

会计信息披露的效率与公平关系到资本市场的效率与公平。基于会计信息产权和会计外部化,会计信息披露可以实现效率与公平的兼顾。职能回缩后的企业会计只提供强制性原始会计信息,维护会计信息披露公平;会计中介机构购买企业的非强制披露会计信息和其它信息,向信息用户有偿提供个性化知识会计信息,以实现会计信息披露效率。     

全液压动力头式钻机在斜孔施工中使用和维护探讨

文章叙述了全液压动力头式岩芯钻机在斜孔施工中的油路走向、特点、日常使用、维护、注意事项及不足,为全液压动力头式岩芯钻机在金属矿斜孔施工中推广使用和维修提出了一些有益的见解,供同行参考借鉴。     

The impact of oil prices and the financial market on cost efficiency in the insurance and Takaful sectors: Evidence from a stochastic frontier analysis

The Gulf Cooperation Council’s (GCC) insurance industry, including conventional insurance and Takaful, has witnessed remarkable growth during the last decade. However, the economies of this region rely on oil as the primary stream of revenue and lack development in financial markets. This could affect the insurance industry. For this reason, this paper examines the impact of oil prices and the financial market on the cost efficiency of the insurance and Takaful sectors in GCC countries using a stochastic frontier cost function with data from 2009–2016. The results show that the relationship between oil prices and efficiency changes from positive to negative when the prices increase, whereas the relationship between the financial market and efficiency is negative. No clear evidence of the impact of oil prices on efficiency arises from the differences between conventional insurance and Takaful. However, there are differences regarding the financial market, with a negative impact on conventional insurance and a positive one on the Takaful business. The results of this study have implications for regulators and management. The Takaful industry is rapidly growing compared to conventional insurance in the GCC and, therefore, the financial market may have added benefits for the GCC region. However, caution is required in relation to the impact of the financial market on conventional insurance. Furthermore, management may require the development of strategies to deal with the nature of GCC economies to avoid shocks to oil prices.