A dynamic model for the optimization of decoupling point and production planning in a supply chain

In this paper, we propose a dynamic model to simultaneously determine the optimal position of the decoupling point and production-inventory plan in a supply chain such that the total cost of the deviation from the target production rate and the target inventory level is minimized. Using the optimal control theory, we derive the closed form of the optimal solution when the production smoothing policy and the zero-inventory policy are applied. The result indicates that under the production smoothing policy, the overestimation of demand rate during the pre-decoupling stage guarantees the existence of the optimal decoupling point; meanwhile the optimal decoupling point exists under zero-inventory policy when the demand rate is underestimated. Also we perform mathematical analysis on the behavior of the optimal production rate and the inventory level and the effect of problem parameters such as the length of the product life cycle and the forecast error on the performance.     

A J–function for inhomogeneous point processes

We propose new summary statistics for intensity‐reweighted moment stationary point processes, that is, point processes with translation invariant n‐point correlation functions for all , that generalise the well known J‐, empty space, and spherical Palm contact distribution functions. We represent these statistics in terms of generating functionals and relate the inhomogeneous J‐function to the inhomogeneous reduced second moment function. Extensions to space time and marked point processes are briefly discussed.     

Monetary policy when wages are downwardly rigid: Friedman meets Tobin

Monetary policy in an economy with both downwardly rigid wages and a transaction motive for money demand is studied using a dynamic stochastic general equilibrium model. The two key features of the model imply that both Tobin's “inflation grease” argument and Friedman's rule are operative, and so optimal inflation may be positive or negative. The Simulated Method of Moments is used to estimate the nonlinear model based on its second-order approximation. Results indicate that the Ramsey policy that maximizes social welfare involves an average inflation rate of about 0.4% per year. In the more realistic case where a central banker follows a simple targeting policy, the optimal inflation target is about 1% per year. We view this result as providing support for the low, but strictly positive, inflation targets used in many countries.     

变频调速技术在大变幅特征水位取水泵站的应用

文章通过对广西钦州市进口资源加工区钦南片区供水工程取水泵站水泵机组选型设计进行分析,浅述变频调速技术在大变幅特征水位取水泵站的应用。     

Efficient versus Sustainable Livestock Grazing in the Sahel

To date, there is no consensus on optimal stocking rates in the semi‐arid Sahel. We develop a model for livestock management based on a detailed analysis of ecosystem dynamics, and we apply it to calculate optimal and sustainable livestock stocking rates in a Sahelian rangeland. The general model accounts for stochastic rainfall and the long‐term impact of grazing on rangeland productivity. For the case study area, the model shows that the optimal stocking rate is higher than the sustainable stocking rate. Hence, with current prices, it is optimal for the pastoralist society to deplete their resource base. In our case study, we also find that the current stocking rate exceeds the optimal stocking rate, which adds to soil depletion.     

基于非对称通胀偏好的最优货币政策规则

与传统的L-Q货币政策分析框架相异,本文通过Linex函数,在央行损失函数中引入非对称通胀目标偏好。新的货币政策动态优化模型分析结果表明,最优货币政策规则中,名义利率对通胀的反应是非线性的,利率工具不仅对通胀水平作出反应,而且对通胀的波动性也作出反应,利率对通胀的变化还产生符号与大小上的非对称。     

基于新技术的煤炭企业节能

分析了煤炭企业的用能及节能现状,介绍了软启动、变频技术和热电冷联供技术及其在煤炭企业的应用,提出了应用新技术的节能措施。     

识别桥梁拉索基频的一种实用方法

斜拉索是现代斜拉桥最重要的结构构件，索力在斜拉桥的施工控制和长期监测中起着重要作用。振动测试法是斜拉桥索力测定、监测和状态评估中应用最广泛的一种方法。振动法测试索力的关键在于准确地识别出索的基频。文章介绍了一种识别拉索基频的实用方法，应用该方法对某斜拉桥拉索的索力进行实测，数据结果表明该方法可行。     

2.1305GHz高频反台温补晶体振荡器的研制

介绍了一种应用离子束刻蚀技术制作的三次泛音355MHz高频反台晶体谐振器，制作2．1305GHz温补晶体振荡器（TCXO）的方法。经测试，该温补晶体振荡器性能优良，且体积和功耗都较小，适用于导弹、无人机、卫星等飞行器。     

Should we subsidize work? Welfare reform,the earned income tax credit and optimal transfers

During the 1990s, US income transfer and tax policies shifted towards trying to encourage work among low-income families. Optimal tax theory, however, suggests that work subsidies are usually an inefficient way to raise the incomes of poor families unless the work effort of recipients has external benefits and/or tax payer/voters prefer redistributing income to the working poor rather than the idle poor. This paper discusses the conditions under which work subsidies may be economically efficient and assesses empirical evidence that suggests that welfare reform and expansions of the EITC have increased work effort among low income families, but is inconclusive about whether the policy shift has enabled them to advance beyond entry-level jobs or benefited their children.