Information systems effectiveness: research designs for causal inference

Abstract. This paper examines the capacity of the research designs of 37 empirical studies of information systems (IS) effectiveness to provide a basis for the development of theories about behaviour related to IS effectiveness. The power of each study to support causal inference was evaluated in terms of (a) its handling of the time dimension, (b) its ability to weigh differences and (c) its resistance to internal validity threats that pose alternative explanations for its reported findings. Of the reviewed studies, 29.7% could account for the time dimension, 32.4% employed a comparison group and 16.2% were not susceptible to any internal validity threats. Only 13.5% of the studies combined an accounting for the time dimension with the use of a comparison group. Of these, however, only 5.4% were also invulnerable to internal validity threats. The research designs of nearly 95% of these published studies were deficient in supporting causal inference. In those studies, suggestions that one variable was causally related to another variable could not be substantiated. Encouragement for the future capacity of IS effectiveness research to support causal inference was found in a trend towards the use of quasiexperimental designs. Recommendations are made regarding ways to increase the inferential capacity of research designs employed in the study of IS effectiveness.     

齿轮磨前滚刀的齿形研究

本文介绍了磨前滚刀滚切齿轮的最大根切量和磨后的渐开线长度计算,并建立了数学模型。为更加直观起见,还建立了模拟滚齿的数学模型。并在实验的基础上提出了参考标准。     

多级脉冲深穿透射孔技术

目前国内较先进的射孔工艺是增效射孔和三相流射孔,这2种射孔工艺均存在射孔深度和造缝深度浅的问题,尤其是对低渗油藏和纵向渗透率远大于横向渗透率的油藏,此造缝深度并不能满足油田生产的需要.介绍了一种新型的射孔技术,它是一种能进行深度射孔造缝的多级射孔技术,利用三级推进剂燃爆时产生峰值不连续的高温、高压气流,形成多级脉冲,多次冲击射孔孔眼前沿的裂缝,使其有效延伸至地层深处,从而较单独的射孔更能有效地增加油气产量.通过地面水泥靶的试验,证明了该射孔器的延缝功能和安全性;通过塘32等井的现场试验,证明该射孔技术对污染地层解堵有显著效果,可明显地降低地层破裂压力.     

通过室内实验及同位素测井技术评价高分子聚合物驱油效果

2500万超高分聚合物室内驱油实验研究了聚合物分子量、浓度、粘度、聚用量、段塞组合等各项性能指标对驱油效果的影响。本文根据室内实验结果,在北一区断西注聚后期开展矿场试验,取得了较好的开发效果。试验前后对比,注入粘度明显增大,月含水上升速度得到有效控制,吸入剖面有了新的动用,有63.1%的油井出现了明显的二次受效特征,取得了显著的经济效益。同时对驱油效果进行系统分析。驱油效果表明:应用2500万超高分聚合物是进一步提高聚驱采收率的有效途径。     

美国食品安全管理法规与举措

以美国国会研究服务部对第107届国会就食品安全方面的一份报告为基础,主要对美国的公共健康问题现状、美国食品安全的联邦规范框架组成、美国食品安全控制最新进展和国会对食品安全提出的新议题做了综述,对我国的食品安全控制和管理体系的建设发挥一点借鉴作用。     

贯彻《水文条例》加强水文科研工作

水文是水利工作乃至国民经济社会发展的基础性和公益性工作。环境的变化、社会的发展、新时期水利工作治水思路转变等均向水文工作提出了新的要求，也提出了许多新的水文科学技术问题。我们应该认真学习贯彻《中华人民共和国水文条例》，加强水文监测工作，加强水文资料的汇交、管理和共享．进一步推进水文现代化建设，推进水文事业的健康发展。     

The problem of definition expansion and contraction

This article is the fourth of a series of articles discussing various open research problems in automated reasoning. The problem proposed for research focuses on finding criteria that would enable an automated reasoning program to expand or contract definitions wisely. For evaluating a proposed solution to this research problem, we include suggestions concerning possible test problems.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under contract W-31-109-Eng-38.     

广东电力特种光缆存在的问题及解决方法

分析了广东电力系统特种光缆应用在工程建设、运行维护等方面出现的问题，以及对电网保护等业务的影响，提出了解决办法和方案，特别是从电网安全运行角度去理解ADSS电腐蚀问题，以及近期广电集团的具体措施。     

企业开展质量成本研究工作的思考

质量成本是指企业为保证产品质量而支出的一切费用，以及产品质量未达到规定的标准而造成的一切损失的总和。开展质量成本研究工作是企业深化质量管理和成本管理的一条有效途径。     

Influence of Production Process Parameters on Fish Oil Quality in a Pilot Plant

ABSTRACT: A pilot plant used for upgrading herring byproducts into fish oil was analyzed on its operational efficiency and product quality. The temperature of the heat exchanger and the speeds of the pump and the 3-phase decanter were varied according to a 2³ fractional factorial design. The initial amount of oxidation products present in the crude oil, its storage stability, and the yields from the different obtained products were determined. Multivariate data analysis of the advanced screening stage showed that T had neither influence on the quality nor on the yield in contrast to D and MP (P < 0.05). Process optimization results showed that the quality of the oil was influenced by an interaction effect between the speed of the MP and the D. Oils processed with the highest MP speed were the most stable during storage.