室内配制混凝土单轴试验全应力-应变曲线试验研究

本文采用TAW-2000微机控制岩石伺服三轴压力试验机,对室内配制普通混凝土圆柱体试件(高径比约2:1)进行单轴受压实验。测定了普通混凝土全应力-应变曲线。通过对试验的研究,循环加载条件下,确实形成了一个封闭的塑性滞回环,且峰后塑性滞回环随循环的次数的增加而变小变窄;加载应力和加载段变形模量呈一定的线性关系;峰后卸载点的应力和峰值应力差越大,峰后曲线的变化越明显,变得越平缓,重新加载曲线的趋近线斜率与初始变形曲线的趋近线斜率相差越大。     

Energy productivity convergence: new evidence from club converging

The goal of this study is to explore the convergence of energy productivity across 31 countries from 1972 to 2012 by using the convergence club algorithm developed by Phillips and Sul (2007). The empirical results lead to the rejection of full convergence and to the presence of a certain number of clubs. The transitional curves, however, indicate that over the long run energy productivity tends to converge, indicating the strong attempts of the countries under investigation to adopt energy policies that eventually contribute to a convergence pattern.     

An analysis of housing expenditure using semiparametric cross-section models

In this paper we model expenditure on housing for owners and renters by means of endogenous switching regression models using cross-section data. We explain the share of housing in total expenditure from family characteristics and total expenditure, where the latter is allowed to be endogenous. We apply various existing parametric and semiparametric techniques for cross-section data. Exogeneity of total expenditure is rejected for the parametric models but not for most semiparametric models. The results are compared on the basis of budget elasticities and graphs of the estimated relationship between the budget share spent on housing and the logarithm of total expenditure. First version received: November 1997 / Final version received: January 2000     

The Effects of Inverted Yield Curves on Asset Returns

Between 1954 and 1991, U.S. stocks, long-term government bonds, and corporate bonds show negative risk premiums during periods preceded by inverted yield curves. Intermediate-term government bonds do not. Going from safer to riskier asset classes, the negative risk premiums increase in absolute value and statistical significance. The consumption CAPM offers a possible explanation for the negative risk premiums. A negative covariance between the growth rate of consumption and the premium on the risky assets will result in a negative risk premium. Empirical tests of the conditional covariance show that the consumption CAPM does not explain the phenomena.     

混流式水轮机过渡过程数值模型研制

文章给出了作者所采用的水轮机综合特性曲线的数值化工作的基本原理及几个实例,并就作者建立的一维管道瞬态流计算,混流式水轮机调保计算,以及小波动过程的动态模拟等程序的工作原理和功能进行了介绍,还提供了几个计算结果作为例证。     

我国地价结构的土地经济学分析

地价是土地市场的重要指标,地价结构能有效反应土地市场结构和状况。我国地价结构为商业地价住宅地价工业地价农业地价,这与传统的土地竞价曲线不一致。本文从产业布局、城市规划、政策导向等角度,运用土地经济学分析方法,重构了我国的土地竞价曲线模式,并对我国地价结构进行了合理解释。结合我国实际,在借鉴日本地价结构比例的基础上,本文提出了适合我国的地价结构比例的建议。     

The Inefficiencies of Regionalised Milk Quota Trade

This paper estimates the inefficiencies associated with the regionalisation of the milk quota trade. An optimisation model is developed to estimate the economic value of quota. Quota values are aggregated to derive quota sale and purchase curves under two scenarios: first, where quotas can be traded nationally and second, where the trade of quota is regionally restricted. Quota trade is simulated and the consequent effects on supplier structure estimated. Through the derivation of sectoral cumulative cost curves it is possible to estimate the impact of regionalising quota trade on sector efficiency. The model is solved using National Farm Survey data from Ireland and the inefficiencies of regionalised quota trade in Ireland are estimated at €27 million. The paper concludes by discussing the implications of restricted quota trade, especially in the context of eventual quota removal.     

乙酰丙酮分光光度法工作曲线稳定性研究

对乙酰丙酮分光光度法测定纺织品中甲醛含量的工作曲线稳定性进行了研究。实验结果表明,乙酰丙酮分光光度法工作曲线有良好的稳定性,相近环境温度不同贮存时间下所作工作曲线斜率的相对标准偏差（RSD）≤2.04%。     

土壤强固剂加固红土的剪切特性

土壤强固剂可以有效改善红土的剪应力-剪位移关系，提高红土的抗剪强度，但对红土剪应力-剪位移关系双曲线的形式影响很小，使红土加固前后的剪应力-剪位移关系及其归一化关系近似呈双曲线型，加固后各双曲线参数减小，而剪应力渐近值、极限剪位移模量和平均剪位移模量却有不同程度的提高，各参数都随垂直压力呈线性变化。     

Reconceptualizing the effects of lean on production costs with evidence from the F-22 program

A central tenet in the theory of lean production is that the implementation of lean practices will reduce waste and thereby decrease costs. However, not all lean implementations have produced such results. Apparently, this effect is moderated by several factors, potentially even to the point of reversal. It is important to increase our understanding of how this might occur. In this paper, we explore how novelty, complexity, instability, and buffering affect the relationship between lean implementation and production costs. An interest in these factors drew us to study the case of Lockheed Martin's production system for the F-22, an extremely complex and innovative product. To build theory, we synthesize our empirical data from the case with other existing theory, such as theories of learning and complexity. Through this analysis, we develop a revised framework that reconceptualizes the effect of lean on production costs and use it to develop 11 propositions to direct further research. Included among these are propositions about how the timing, scale, and extent of lean implementation can regulate the benefits of lean. Furthermore, when the objective of lean is construed as the provision of value, we propose that this value is an emergent property of a complex process, different from the mere sum of the values provided by its constituent tasks. Therefore, the elimination of tasks will not guarantee cost reduction, and lean may provide even greater value by incorporating some aspects of agile manufacturing. Overall, we develop a fuller range of the effects of lean practices on production costs and illuminate how operations managers might control key variables to draw greater benefits from lean implementation.