基于MATLAB和Labwindows/CVI的车辆刹车系统仿真研究

汽车刹车系统的性能直接影响到驾驶员及乘客的安全。文章以某型汽车为研究背景,依据该型汽车在刹车过程中的动力学特性,建立了该型汽车在刹车过程中的系统模型,然后利用Matlab/Simulink对该系统建立后台仿真模型,并通过CVI实现上层仿真控制台。最后,通过仿真实验对该系统模型的准确性进行了验证。系统仿真结果表明所建立的汽车刹车系统模型具有较高的准确性,同时也说明了文中所采用的方法的可行性。     

BUCK变换器仿真分析及实现

文章通过对开关电源的研究,介绍了BUCK变换器的工作原理,根据变换器的原理在Matlab/Simulink环境下建立BUCK变换器仿真模型。根据该模型搭建实验电路,从实验中测得BUCK变换器在不同输入与不同占空比的情况下所得到的不同输出,将实验结果与仿真结果的数据进行对比,两者误差在工程应用允许范围内,为整个充放电系统进一步研究提供了参考价值。     

用Flexsim求解整数线性规划问题

为了进一步开拓思路,探索物流仿真软件Flexsim在更深层次和更广范围的应用,基于一个简单的整数线性规划例题建立了相应的仿真模型,通过修改代码使该模型能够模拟例题中阐述的问题,最终利用实验器实现了对枚举法的模拟。仿真结果得出的最优方案与传统方法计算的结果一致。由此可知,当整数线性规划问题比较简单时,应用Flexsim建立对应的模型,利用实验器可以实现对该问题的求解。     

基于改进的二阶阻容等效电路模型的锂电池建模仿真

为了更加精确地描述锂离子电池的工作特性,在传统二阶Thevenin模型的基础上考虑电池的滞回电压特性与充放电电阻特性,建立改进的二阶阻容等效电路模型。在Matlab/simulink中建立电池仿真模型,通过HPPC实验对电池的参数进行辨识。借助Matlab中的Cftool工具箱对数据进行多项式拟合。之后经过恒流放电实验和脉冲放电实验对模型进行验证分析,通过仿真结果与实验结果的对比分析,发现该模型在恒流放电实验中仿真电压与真实电压的误差低于0.05V,在脉冲放电实验中的误差低于0.025V,验证了改进的锂离子电池模型的准确性,满足工程需要。     

劳动力市场中统计性歧视的模型分析

菲尔普斯最早建立了劳动力市场中的统计性歧视模型，埃格勒和克恩后来从风险回避角度建立了一个不同的模型。本文认为这两个模型都存在明显的缺陷，并试图重新构建模型，给出统计性歧视的一个更为合理的解释。     

配送中心订单处理作业流程仿真研究

对订单处理系统相关文献归纳总结的基础上,进一步分析订单处理的作业流程。分析认为,可以用排队系统建模仿真的方法解决订单处理的相关问题。以某网上商城订单处理流程为例,采用实体流程图法建立该流程的系统模型,并利用WITNESS仿真软件建立了仿真模型。仿真实验的结果指明最优人员配置和系统的进一步优化方向。     

TORNADO燃机故障诊断的神经网络模型研究

为改善单神经网络收敛速度慢的问题,本文采用组合神经网络建模方法,建立了燃机性能仿真网络模型,并进行实验验证。建模过程中,将建模对象划分为三个相对独立的子网络,利用获取的实验数据组成训练域对网络进行训练,建立起一套可用于燃气轮机控制系统仿真及故障诊断的组合神经网络模型。实验结果表明:该模型平均输出误差约为3%-6%,计算时间小于100ms,可用于基于模型的燃气轮机诊断系统。     

基于人工神经网络的分供方评价模型

分析了分供方评价的定性方法和多平价法的不足之处，建立了分供方评价的人工神经网络模型，从产品质量的保证能力等方面进行综合评价。仿真实验表明，人工神经网络用于分供方评价，其结果是令人满意的。     

基于人工免疫算法的多无人机分布式任务分配方法

对多无人机任务分配问题进行了研究,在重量和路径负载均衡的基础上建立了带有攻击顺序的01决策变量的模型,运用分布式的人工免疫算法对该模型进行仿真实验,最终得到每个无人机攻击的目标顺序以及目标函数值,实验证明该方法在得到不劣于遗传算法结果的同时,提高了寻找最优解的收敛速度。     

微电网中部分电源设备建模研究

微电网仿真研究需要准确的元件模型，其中重要的组成部分就是电源的选择，本文以两种光伏电池和燃料电池为例，对其建立了等效模型，模型简单且符合工程需求，该模型能对基于MATLAB进行仿真研究时提供参考。     

医学生自愿性失业的经济学分析

本文从大学生毕业供求关系、二元劳动力市场理论和保留工资理论的角度分析,医学生自愿性失业的原因。并提出解决医学生自愿性失业问题,应更多地发挥市场机制的作用,调解医学生毕业供求,打破劳动力市场的分割,从而使大学生自觉主动地调整就业期望值。     

Subsidizing low-skilled jobs in a dual labor market

We introduce a matching model that allows for classical and frictional unemployment. The labor market is dual featuring low-skilled and high-skilled workers and simple and complex jobs. Simple jobs pay a minimum wage, while wages in the complex jobs are determined by Nash bargaining. Opportunities for low-skilled workers are limited to simple jobs; while high-skilled unemployed can apply for both types of jobs, and thereby can accept to be downgraded. We analyze the outcomes of simple job subsidy policies assuming that government budget is balanced through taxes on occupied workers. We first give conditions for the existence and uniqueness of a steady-state equilibrium and we then analyze the effects of different fiscal instruments. We show that in this set-up, increasing simple job subsidies does not necessarily reduce low-skilled unemployment or unemployment spells. By introducing heterogeneous skills and possible downgrading of the high-skilled workers, we show that the effectiveness of such policies in reducing the classical unemployment is decreasing. In fact, any additional classical unemployed re-entering the job market is accompanied by an increasing number of high-skilled workers downgrading to low-skilled jobs. We calibrate the model on French labor market data. It is found that for five low-skilled workers leaving classical unemployment, two high-skilled workers are downgraded.     

Uncertainty-driven labor market fluctuations

This paper explores uncertainty shocks as a driving force in a search and matching model of the labor market. Uncertainty takes the form of a noisy component in a firm׳s initial signal about job productivity. Greater uncertainty dampens job creation by increasing the risk of making the costly mistake of investing in jobs that will turn out to be unprofitable. Thus, uncertainty shocks can cause labor market downturns: lower vacancy rates, lower job-finding rates, and higher unemployment. Numerical simulations examine the level of volatility and the cross-correlations and autocorrelations of key U.S. labor market indicators that result from fluctuations driven by changes in uncertainty.     

Relaxing Hukou: Increased labor mobility and China’s economic geography

China’s Hukou system poses severe restrictions on labor mobility. This paper assesses the possible consequences of relaxing these restrictions for China’s internal economic geography. We base our analysis on a new economic geography (NEG) model. First, we estimate the important model parameters using data on 264 of China’s prefecture cities. Second, we use these estimates as inputs in a simulation of the full NEG model under different labor mobility regimes. We find that increased labor mobility leads to more pronounced core–periphery outcomes. Beijing, Shanghai, Guangzhou and Chongqing in particular will further strengthen their dominant place in China’s urban hierarchy. In addition, two other groups of cities can be distinguished: those in China’s populous heartland offering preferential access to China’s enormous internal market, and more peripheral cities that are better shielded from competition with China’s economic heartland by virtue of their relative remoteness.     

Panel data estimates of the production function and product and labor market imperfections

Consistent with two models of imperfect competition in the labor market—the efficient bargaining model and the monopsony model—we provide two extensions of a microeconomic version of Hall's framework for estimating price‐cost margins. We show that both product and labor market imperfections generate a wedge between factor elasticities in the production function and their corresponding shares in revenue, which can be characterized by a ‘joint market imperfections parameter’. Using an unbalanced panel of 10,646 French firms in 38 manufacturing industries over the period 1978–2001, we can classify these industries into six different regimes depending on the type of competition in the product and the labor market. By far the most predominant regime is one of imperfect competition in the product market and efficient bargaining in the labor market (IC‐EB), followed by a regime of imperfect competition in the product market and perfect competition or right‐to‐manage bargaining in the labor market (IC‐PR), and by a regime of perfect competition in the product market and monopsony in the labor market (PC‐MO). For each of these three predominant regimes, we assess within‐regime firm differences in the estimated average price‐cost mark‐up and rent sharing or labor supply elasticity parameters, following the Swamy methodology to determine the degree of true firm dispersion. To assess the plausibility of our findings in the case of the dominant regime (IC‐EB), we also relate our industry and firm‐level estimates of price‐cost mark‐up and extent of rent sharing to industry characteristics and firm‐specific variables respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Precise computation of a competitive equilibrium of the discrete land market model

This paper provides a finite algorithm to compute a competitive equilibrium of the Alonso-type discrete land market model (known as bid-rent equilibrium) without assuming any condition on the spatial configuration such as monocentricity. The existence of the finite algorithm implies that the discrete land market model is sufficiently tractable for computer simulation analysis (sensitivity analysis) even if the spatial configuration is variable. Specifically, we can evaluate numerically the effects of new routes in a transportation network upon equilibrium rents and commuting mode.     

工资粘性、经济波动与货币政策模拟——基于DSGE模型的分析

本文在BGG模型的基础上,引入了工资粘性,使之成为综合考虑价格粘性、金融加速器效应以及工资粘性的DSGE模型,我们模拟并比较了中国不同货币政策的影响。贝叶斯估计结果验证了中国工资粘性的存在,说明中国劳动力市场的配置尚存在改善的余地。货币政策模拟结果显示,价格型货币政策效应较强但持续期较短,而数量型货币政策效应较为温和但影响相对持久,央行需注重价格型货币政策与数量型货币政策的合理搭配与使用。     

Dualism in the German Labor Market?A Nonparametric Analysis with Panel Data

A bstract . Orthodoxy in economics gives pride of place to the hypothesis of compensating differentials. Applied to job quality criteria, such as wage levels, job stability, and wage growth, the compensating differentials hypothesis implies that negative or positive job quality characteristics should— ceteris paribus —rarely coincide. Originating in the late 1960s from studies of American inner-city labor markets, dualist labor market theory has raised doubts about this assumption. At its core, dualist analysis proposes that a dualism exists between a primary' labor market where "jobs possess several of the following traits: high wages, good working conditions, employment stability and job security, equity and due process in the administration of work, and chances for advancement" and a secondary market where jobs "tend to involve low wages, poor working conditions, considerable variability in employment, and little opportunity to advance" (Doeringer and Piore 1971). In the 1980s, there were several attempts to apply dual or segmented labor market theory to European economies, including the German labor market. The mixed findings of these analyses have cast doubt upon the transferability of dualist theory to these contexts.     

价格涨跌幅机制对市场波动及换手率的影响

文章调查了价格限制机制对股票价格波动以及市场流动性的影响。首先刻画了实行价格涨跌幅限制后股票价格的变化特征,研究价格限制机制对股票价格波动的影响;随后在考虑延续冲击效应因素的基础上,通过对引入价格限制机制后投资者总成本的考察,研究了该机制对市场流动性的影响。文章结论认为,股票价格涨跌幅限制机制的引入,将增加股票市场的波动性,并且会导致投资者心理所能承受的潜在收益、损失量减小,使投资者更加频繁地买卖股票．从而增加市场换手率,进而提高整个市场的流动性。     

劳动力市场的二元结构

本文在效率工资理论基本逻辑基础上建立模型,分析劳动力市场的二元结构,即高技能劳动力的相对短缺和低技能劳动力的过剩。基本结论是,雇主与雇员信息不对称,雇主有激励去实施效率工资,由于同样工作给高技能劳动力带来边际劳动负效用低于低技能劳动力,继而对高技能劳动力的效率工资效果好于对低技能劳动力,所以雇主倾向于雇用高技能劳动力。这样,在一定劳动力供给结构下,高技能劳动者就相对短缺,而低技能劳动者则过剩。