配送中心分拣作业系统的策略研究

配送中心是以组织配送性销售或供应,执行实物配送为主要职能的流通型结点,是物流产业中不可缺少的一种经济组织形式。在配送中心作业中,分拣配货就成为配送中心的核心作业,其作业效率会直接影响配送中心的运作效率,也会影响配送中心的服务水平。配送中心的分拣作业的分拣策略包括分区策略、订单处理策略和货物分类策略,不同的策略组合其作业的复杂程度也不同,适合于不同配送中心的分拣作业系统。     

基于农村循环经济的垃圾分类处理方法及运行管理模式分析

农村垃圾污染问题已成为当前农村最急需解决的环境问题。介绍了我国农村垃圾排放现状、特点以及污染危害,通过分析目前垃圾分类处理不充分的原因,因地制宜提出基于农村循环经济的垃圾分类处理方法及运行管理模式,以提高垃圾分类处理的科学性,满足环境保护的要求。     

利用频移动态特征的辐射源目标盲分选

利用辐射源目标的频移动态特征进行盲分选时,针对已有的分选方法不能很好解决非合作接收数据非周期、间断、交叠的问题,提出了一种改进的逻辑回归分选算法,将信号分选转化为轨迹分类的问题来处理。首先,借鉴多目标航迹起始模型中的M/N逻辑法的框架,设计新的数据关联门限,以建立目标起始曲线;其次,采用最小二乘拟合方法替代卡尔曼滤波,设计新的外推规则,建立载频变化预测曲线;分析新的接收数据与预测曲线的关联性,不断迭代回归或形成新的分支,最后获得目标分选结果。仿真与实测试验表明,利用逻辑回归分选算法,对不同运动目标搭载的同频辐射源可进行自动分选,4个仿真目标与2个真实目标的分选正确率达到100%。同时,该方法拓展了辐射源目标盲分选中的动态频移特征应用,为辐射源个体识别提供了新的支持。     

Incentives and the Sorting of Altruistic Agents into Street‐Level Bureaucracies*

Many street‐level bureaucrats have the dual task of helping some clients, while sanctioning others. We develop a model of a street‐level bureaucracy, and we study the implications of its personnel policy on the self‐selection and allocation decisions of agents who differ in altruism towards clients. When bureaucrats are paid flat wages, they do not sanction, and the most altruistic types sort into bureaucracy. Pay‐for‐performance induces some bureaucrats to sanction, but it necessitates an increase in compensation, which can result in sorting from the top and bottom of the altruism distribution. We also explain why street‐level bureaucrats often experience an overload of clients.     

分拣导入物料的投影尺寸及近似体积测量计算方法

分析了目前自动化物流分拣输送系统在物料导入输送环节的工艺特点和设备控制现状,并结合应用光电检测、工业可编程控制等技术,针对水平交叉带分拣输送机应用场景,对其中物料导入控制环节所面临的物料外形尺寸测量和计算问题,提出了基于物料轮廓最大值检测、尺寸特征捕捉、长宽比关系判断等要素来对物料投影尺寸进行测量的计算方法,具有数据采集实时、程序编写简单、运算量少等特点;同时基于对导入输送的物料进行横向、纵向的截面段断层扫描测量并累加计算,以较低的器件成本及较少的控制器程序运算量,实现对物料体积的近似测量计算,是一种较为经济和可取的控制计算方法。     

Which school systems sort weaker students into smaller classes? International evidence

We examine whether the sorting of high- and low-achieving students into classes of different sizes results in a regressive or compensatory pattern of class sizes for 18 national school systems. Sorting effects are identified by subtracting the causal effect of class size on performance from their total correlation. Our empirical results reveal strongly compensatory patterns of sorting within and especially between schools in many countries. Only the United States, which has a decentralized education finance and considerable residential mobility, exhibits regressive between-school sorting. Between-school sorting is more compensatory in systems with ability tracking. Within-school sorting is more compensatory where administrators rather than teachers assign students to classrooms.     

The electoral migration cycle

This paper proposes a new test of Tiebout sorting that relies on the exogenous time structure of recurrent local elections. The test is based on the idea that competitive elections represent periodic perturbations to the Tiebout equilibrium of local public good provision and allocation of households to communities, so that their schedule should affect the timing of households' sorting decisions. On the other hand, internal migration flows that have nothing to do with the demand for public goods over which localities vote recurrently ought to be orthogonal to the timing of elections in a reduced-form migration equation. I exploit the staggered schedule of mayoral elections in Italy to analyze migration, elections, and public budget data across several thousands of municipalities, and find evidence of a systematic influence of the electoral calendar on the timing of sorting decisions.     

Why I am a Psychology Major: An Empirical Analysis of Student Motivations

The underlying “architecture of the decision to pursue a degree in psychology was quantified using the Method of Sorting technique to identifying the critical issues necessary to make this choice. Multidimentsional scaling procedures were employed to construct a three-dimensional map representing the relationships between reasons for selecting psychology as a major. Freshman and senior psychology majors (N = 165) from a regional university and a large research-based institution rated the relative importance of items in their decision-making process. Hierarchical clustering procedures revealed seven different groups of students. Although significant differences associated with class standing were not found, institutional affiliation did influence cluster composition. Reflecting local emphases, students at the regional institution had a greater interest in Counseling Psychology, whereas those at the research-based school focused on Clinical Psychology. This semantic map and the associated item clusters arising from psychology student data provides an empirical basis for, amongst other things, course selection, faculty-initiated program design or revision, strategic niche marketing, and student retention.     

农业水价利益相关者定量排序研究

[目的]我国农业水价综合改革工作推进正面临诸多阻碍,文章通过利益相关者理论研究农业水价问题,明确农业水价利益相关者间的关系,并对农业水价综合改革工作产生积极影响。[方法]通过文献调研和实地调研相结合的研究方式,对农业水价的利益相关者进行了识别、确定;同时运用"Mitchell"评分法、专家打分法等方法,以利益相关者的3个属性为切入点,由领域内权威专家对农业水价的各利益相关者进行打分,最终确定农业水价利益相关者定量排序。[结果]农业水价利益相关者排序呈现:政府部门农户及其组织其他社会机构。同时结合农业水价综合改革情况分析确定了农业水价利益相关者综合排序及各属性排序结果的合理性。[结论]农业水价利益相关者定量排序以定量的形式展示了农业水价利益相关者间的关系,并为农业水价合理分担的进一步研究提供了重要基础。     

旋转式砂粒分选机的设计

本次设计的主要任务便是设计一台砂粒自动分选机,与已有的进出料设备进行连接,从而完善喷丸处理工艺过程,最大限度的保护现场的工作人员和减轻劳动强度。