装箱机双四杆机构的动力学仿真分析及结构优化

为了减轻双四杆装箱机机构的质量，以减少实际生产过程中的耗材,采用Pro/E建立了装箱机双四杆机构零件的三维模型，并导入ADAMS软件建立了虚拟样机，然后进行动力学仿真，得到杆的受力数据，接着运用MATLAB软件对这些数据进行处理，分别对其进行抗拉形式和抗弯形式强度分析和校核，最后在满足强度的条件下得到较合理的截面参数和形状。     

经营规模受限情况下的农机选型方法研究

通过计算一定土地规模条件下运用某农业机械的经济成本,作为机具选型的依据。并探索随着土地经营规模的改变,机具选型结果的变化规律。研究发现,一般情况下,土地规模较小时,作业效率低但价格很便宜的机型经济成本较低;土地经营规模较大时,价格较贵但作业效率很高的机型逐渐占据优势。因此,当现实中农业生产经营者的土地规模较小时,可以选择购买价格较低但可靠性相对较好的国产农业机械,而不是盲目地跟风购买经济成本很高的进口农业机械。     

‘National Machineries’ and Authoritarian Politics

Abstract

Why do authoritarian states adopt ‘state feminist’ policies, and what are the effects of these initiatives? This article expands our understanding of state feminist institutions in non-democracies by examining the development of a women's national machinery in Cameroon. It argues that the Cameroonian state has adopted a national machinery because: (1) it provides low-cost international legitimacy; (2) it attracts international assistance; (3) this assistance fuels domestic patronage networks; and (4) the national machinery channels women's activism toward state-delineated projects and goals. These motives undercut its ability to promote women's advancement. National machineries in authoritarian contexts are not just plagued by technical problems and funding shortages but also by competing agendas within the state apparatus and a lack of a commitment by high-level government officials to improving women's status in society.     

《机床电气系统装调与检修》项目化课程的设计与实施

剖析了传统高职《机床电气系统装调与检修》课程教学过程中普遍存在的问题,提出了进行课程项目化改革的思路：基于工作任务重构课程目标、课程结构、课程内容和课程评价,采用任务驱动等多种教学方法实施教学活动,加强实训条件和师资建设。教学实践证明,项目化教学有利于学生职业能力的提高和职业素质的养成。     

Scheduling tool changes and special jobs on a single machine to minimize makespan

This paper considers a variation of the classical single machine scheduling problem with tool changes. In the variation, two sets of jobs, namely special jobs and normal jobs, are considered. By special jobs, we mean that each special job must be processed within the first prefixed time units of a tool life. To solve the scheduling problem with small size and moderate size, we propose two mathematical programming models. To solve the scheduling problem with large size, we propose three sets of algorithms and focus on the performance of six algorithms based on the studies of a new bin packing problem. Worst-case analysis is conducted. Numerical experiment shows that each of the six algorithms can solve instances with up to 5000 jobs in about 0.5 s with an average relative error less than 4%.     

Combinatorial design of a minimum cost transfer line

The problem of equipment selection for a production line is considered. Each piece of equipment, also called unit or block, performs a set of operations. All necessary operations of the line and all available blocks with their costs are known. The difficulty is to choose the most appropriate blocks and group them into (work)stations. There are some constraints that restrict the assignment of different blocks to the same station. Two combinatorial approaches for solving this problem are suggested. Both are based on a novel concept of locally feasible stations. The first approach combinatorially enumerates all feasible solutions, and the second reduces the problem to search for a maximum weight clique. A boolean linear program based on a set packing formulation is presented. Computer experiments with benchmark data are described. Their results show that the set packing model is competitive and can be used to solve real-life problems.     

出口退税调整对机电行业上市公司的影响研究

通过观察股票市场收益率的变动,分析了2008年12月29日机电行业退税率调整对不同类型上市公司的影响效果。首先,对机电行业5类市场指数进行干预分析,实证显示此次政策调整对2009年以后机电各行业市场的日收益率有显著正影响。其次,运用两因素模型计算12月29日当天样本企业股票的异常收益率。最后,对样本企业实验分组,选取企业出口倾向和国际化程度等变量解释不同类型企业的异常收益率。结果表明,此次调整更有利于机电产品出口业务量大、业务趋于扩张的企业,并且相对市场力量型和相对非市场力量型的企业均获得经济利润,但前者获得的经济利润高于后者,揭示了出口退税率调整存在一定的政策偏离。     

企业家精神、国际契机与民族国家建构——辛亥革命前后中国机械制造业的发展(1900—1920)

辛亥革命前后十年间,中国机械制造业的发展并未受政治波动的太大影响,依然按照内部动力继续演化。该时期中国的机械制造业繁荣一时,但若干领军企业陷于失败。在辛亥前后,中国机械制造业的发展主要是企业家精神推动的结果,而这种企业家精神既包括创新精神,又包含民族主义。第一次世界大战对中国机械制造业产生了双重影响,以负面影响为主。北洋政权对于机械制造业的发展基本上未起促进作用,辛亥时期中国的国家建构与工业发展之间的关联还处于较低层次。但辛亥革命释放的民族主义力量加速了中国机械制造业的演化。     

贵州山区农机市场分析及进入策略

贵州农业机械市场正处于发展阶段。农业机械企业如何发挥自身优势,面对外部的机遇与挑战是参与竞争的首要问题。应从外部因素和自身条件来综合分析企业市场进入策略。     

国内外食品机械的发展现状及发展趋势

论述了目前国内外食品机械的发展现状及食品机械的发展趋势 ,提出了发展我国食品机械的一些措施