Pathways of change in social mobility: Industrialization,education and growing fluidity in Brazil

This paper explores the change in intergenerational class mobility over the last quarter-century in Brazil. Using repeated cross-sectional surveys between the early 1970s and the late 1990s and a counterfactual approach, we disentangle cohort from period interpretations of change, and examine the mechanisms driving change in fluidity among Brazilian men. We detect a substantial increase in social fluidity over time, which emerges from period transformation, rather than cohort replacement. This trend departs from industrialized nations, where growing fluidity has been found to be entirely driven by the replacement of older, more rigid cohorts by younger, more fluid ones, and to emerge from educational equalization and a “compositional effect”—educational expansion combined with a weaker intergenerational association among those with higher education. In contrast, in a context of rapid late industrialization, two mechanisms account for growing fluidity in Brazil: the decline in the “economic returns to schooling”, and the weakening of the direct influence of class origins on class destination, net of education. We discuss the implications of these patterns for the understanding of mobility dynamics in different national contexts.     

Simulated maximum likelihood estimation in joint models for multiple longitudinal markers and recurrent events of multiple types,in the presence of a terminal event

In medical studies we are often confronted with complex longitudinal data. During the follow-up period, which can be ended prematurely by a terminal event (e.g. death), a subject can experience recurrent events of multiple types. In addition, we collect repeated measurements from multiple markers. An adverse health status, represented by ‘bad’ marker values and an abnormal number of recurrent events, is often associated with the risk of experiencing the terminal event. In this situation, the missingness of the data is not at random and, to avoid bias, it is necessary to model all data simultaneously using a joint model. The correlations between the repeated observations of a marker or an event type within an individual are captured by normally distributed random effects. Because the joint likelihood contains an analytically intractable integral, Bayesian approaches or quadrature approximation techniques are necessary to evaluate the likelihood. However, when the number of recurrent event types and markers is large, the dimensionality of the integral is high and these methods are too computationally expensive. As an alternative, we propose a simulated maximum-likelihood approach based on quasi-Monte Carlo integration to evaluate the likelihood of joint models with multiple recurrent event types and markers.     

Estimation of parameters of Misclassified Size Biased Discrete Lindley Distribution

In this paper, a two-parameter discrete distribution named Misclassified Size Biased Discrete Lindley distribution is defined under the situation of misclassification where some of the observations corresponding to x = c + 1 are reported as x = c with misclassification errorα. Different estimation methods like maximum likelihood estimation, moment estimation, and Bayes Estimation are considered to estimate the parameters of Misclassified Size Biased Discrete Lindley distribution. These methods are compared by using mean square error through simulation study with varying sample sizes. Further general form of factorial moment is also obtained for Misclassified Size Biased Discrete Lindley distribution. Real life data set is used to fit Misclassified Size Biased Discrete Lindley distribution.     

社会主义核心价值观的历史逻辑性

以大梁峁特长公路隧道为依托,针对水平层状岩体隧道,采用ANSYS数值分析软件将水平泥岩砂岩互层岩体等效为正交各向异性的方式,对隧道开挖过程中围岩稳定性进行了数值试验分析,通过分析围岩塑性区、围岩应力、隧道变形、锚杆轴力、初支及二衬内力,得出施工采用支护参数的合理性和水平泥岩砂岩互层隧道围岩变形和初支、二衬应力的分布特征。     

基于内生增长模型的货币政策效应研究

货币政策是维系经济系统正常运行的必要条件。关于货币政策效应问题一直都未形成统一意见,在此背景下厘清中国货币政策问题有着重要意义。在内生增长理论框架下构建一个包含货币参数的经济增长模型来考察货币供给对经济增长的影响,数值模拟表明在稳定状态下货币供给与经济增长之间呈现倒U型关系。为了验证理论分析结果在实际经济中的适用性,以中国2000—2013年经济数据为例,采用分位数回归模型进行实证检验,实证结果不仅验证了理论分析结果的正确性,也证明了倒U型关系的稳健性。     

高压功率器件特性的数值分析

在求解高压功率(HV/P)器件的泊松方程与连续性方程中,将与注入和掺杂有关的因子引入物理参数模型。针对HV/P器件分析程序特有的收敛与溢出问题,采用从低电压到高电压的分段解法和归一化的模拟方法。利用此程序对HV/P器件具有场限环和场板结构的特性进行了模拟。     

基于软开关技术的斩波电路仿真

本文介绍了软开关变换相对于传统电路中硬开关变换的优点,对几种典型的软开关进行了叙述和比较,并给出了其中两个有代表性变换电路的multisim仿真结果,最后提出了软开关技术的发展趋势。     

Linking Product Planning and Process Design Decisions

Manufacturing strategy reflects the goals of the business strategy and directs the manufacturing function in achieving them. In this study, we focus on two decision areas with crucial implications for manufacturing strategy: product planning and process design. Using mathematical programming models as a research tool, we test several conjectures in the manufacturing strategy literature regarding linkages between the two decisions. Our results show that a close integration between these decisions helps control the product offerings, stabilize process requirements, improve process technology choices, and increase net cash flows over time. Using the concept of environmental clusters, we found that a close linkage is more critical when the environment is more complex, less uncertain, and tighter. Based on these findings, we present some managerial implications and suggestions for future research.     

Improving the Utilization of Front-Line Service Delivery System Personnel*

There are two types of work typically performed in services which differ in the degree of control management has over when the work must be done. Serving customers, an activity that can occur only when customers are in the system is, by its nature, uncontrollable work. In contrast, the execution of controllable work does not require the presence of customers, and is work over which management has some degree of temporal control. This paper presents two integer programming models for optimally scheduling controllable work simultaneously with shifts. One model explicitly defines variables for the times at which controllable work may be started, while the other uses implicit modeling to reduce the number of variables. In an initial experiment of 864 test problems, the latter model yielded optimal solutions in approximately 81 percent of the time required by the former model. To evaluate the impact on customer service of having front-line employees perform controllable work, a second experiment was conducted simulating 5, 832 service delivery systems. The results show that controllable work offers a useful means of improving labor utilization. Perhaps more important, it was found that having front-line employees perform controllable work did not degrade the desired level of customer service.     

A Simulation Study of Sequencing Rules in a Kanban-Controlled Flow Shop*

This paper addresses the problem of sequencing in decentralized kanban-controlled flow shops. The kanban production control system considered uses two card types and a constant withdrawal period. The flow shops are decentralized in the sense that sequencing decisions are made at the local workstation level rather than by a centralized scheduling system. Further, there are no material requirements planning (MRP)-generated due dates available to drive dispatching rules such as earliest due date, slack, and critical ratio. Local sequencing rules suitable for the decentralized kanban production-control environment are proposed and tested in a simulation experiment. These rules are designed so that they can be implemented with only the information available at the workstation level. Example sequencing problems are used to show why the shortest processing time rule minimizes neither average work-in-process inventory nor average finished-goods withdrawal kanban waiting time. Further, it is shown how work station supervisors can use the withdrawal period, in addition to the number of kanbans, to manage work-in-process inventories.