浅谈农机报废更新工作开展的必要性

老旧农机具能耗高,尾气排放量大,对环境污染严重,在一定程度上影响了机具的规范使用和管理。文章对提升农机化发展水平,迫切需要开展农机报废更新工作指出其必要性,并提出了相关具体工作措施。     

Measuring consistency in TTL-based caches

We propose a general modeling framework to evaluate the performance of cache consistency algorithms. In addition to the usual hit rate, we introduce the hit^* rate as a consistency measure, which captures the fraction of non-stale downloads from the cache. We apply these ideas to the analysis of the fixed TTL consistency algorithm in the presence of network delays. The hit and hit^* rates are evaluated when requests and updates are modeled by renewal processes. Classical results on the renewal function lead to various bounds.     

北京市危旧房改造的多目标分解模式

由于政府、居民、开发商之间复杂的博弈,北京市1990年提出的综合性危改目标遇到了很大的挑战,为解决这一问题,本文提出危旧房改造的目标分解模式,即建立一个以危改区域或危改项目为导向的危改目标实现框架,将北京市危旧房改造的多重目标进行分解,然后制定相应的分目标政策,建立相应的分目标制度,采取相应的分目标措施,最终从总体上实现危旧房改造的目标,主导目标的确定应遵循四个基本原则,最后提出几个政策建议。     

机械设备大修理与否的经济界限的确定

机械设备的大修理与更新之间存在合理的经济界限。针对传统的确定二者之界限的数学模型提出改进，确定了大修理与重置更新界限的比较原则与方法。     

人类聚居环境学对于居住区规划设计的启示

以人类聚居环境学的研究方法从若干方面对目前的居住区规划设计进行了一定的探讨,分析规划设计及建设方面目前存在的主要问题,提出以人类聚居环境学为指导的居住区规划设计理念。     

首钢2号高炉的技术进步

介绍首钢2号高炉大修采用的新技术、开炉操作和投产以来的生产情况。     

A method for the efficient prioritization of infrastructure renewal projects

The infrastructure renewal program at MIT consists of a large number of projects with an estimated budget that could approach $1 billion. Infrastructure renewal at the Massachusetts Institute of Technology (MIT) is the process of evaluating and investing in the maintenance of facility systems and basic structure to preserve existing campus buildings. The selection and prioritization of projects must be addressed with a systematic method for the optimal allocation of funds and other resources. This paper presents a case study of a prioritization method utilizing multi-attribute utility theory. This method was developed at MIT's Department of Nuclear Engineering and was deployed by the Department of Facilities after appropriate modifications were implemented to address the idiosyncrasies of infrastructure renewal projects and the competing criteria and constraints that influence the judgment of the decision-makers. Such criteria include minimization of risk, optimization of economic impact, and coordination with academic policies, programs, and operations of the Institute. A brief overview of the method is presented, as well as the results of its application to the prioritization of infrastructure renewal projects. Results of workshops held at MIT with the participation of stakeholders demonstrate the feasibility of the prioritization method and the usefulness of this approach.     

Quadratic control of stochastic hybrid systems with renewal transitions

We study the quadratic control of a class of stochastic hybrid systems with linear continuous dynamics for which the lengths of time that the system stays in each mode are independent random variables with given probability distribution functions. We derive a condition for finding the optimal feedback policy that minimizes a discounted infinite horizon cost. We show that the optimal cost is the solution to a set of differential equations with unknown boundary conditions. Furthermore, we provide a recursive algorithm for computing the optimal cost and the optimal feedback policy. The applicability of our result is illustrated through a numerical example, motivated by stochastic gene regulation in biology.     

基于灰色新陈代谢神经网络的管网末梢水质预测模型研究

针对管网末梢水质环境存在信息不确定、非线性的情况,本文结合灰色预测＂贫信息＂及BP神经网络非线性拟合强的优点,提出了灰色新陈代谢神经网络预测模型。该模型采用灰色新陈代谢GM（1,1）模型对BP网络的输入样本进行预处理,解决了BP网络需要大量学习样本的局限。仿真结果表明,与灰色新陈代谢、BP神经网络相比,灰色新陈代谢神经网络预测精度更高。     

“以人为本”理念支撑下高校ASP.NET课程教学体系构建

在新环境下,打破高等教育传统教学模式,建立以人为本的教学模式以适应时代的进步。ASP.NET是微软推出建立动态WEB应用程序的技术,在ASP.NET课程教学中深入以人为本的理念,以学生主体为出发点,展开教学内容安排、教学项目案例设计、教学策略及教学方法、考核方式等方面的研究,构建以人为本的立体化教学体系,供高校或培训机构参考。