控轧控冷工艺对60Si_2Mn弹簧钢组织性能的影响

在实验室条件下研究了控轧控冷工艺对60 Si_2Mn弹簧钢组织性能的影响。研究表明:60Si_2Mn钢采用奥氏体再结晶区控轧,轧后以6～10℃/s冷却速度控制冷却,可获得球团细小且均匀的珠光体加少量铁素体组织,热轧钢材的强韧性显著提高,同时减少了脱碳。     

管理层权力与企业价值：基于产品市场竞争的视角

以2005－2011年上海证券交易所A股市场为研究对象,将个人和机构投资者情绪的影响进行对比研究以明确两种情绪在市场中扮演的角色。以往的相关研究大多关注两者的相互影响或其中一种对市场的影响,本文将两者同时考虑,并利用滚动回归方法从量化股票收益对投资者情绪变化的敏感度这一新视角深入到个股层面。研究表明:机构投资者情绪可以帮助预测个人投资者情绪,反之不成立;另外,机构投资者在市场上表现得更为理性,他们的情绪能够预测后市,而个人投资者情绪不具有预测性;进一步研究后发现,投资者关注度越高的股票,其收益对投资者情绪变化的敏感度越高,这种现象无论是在对个人还是对机构投资者情绪变化的敏感度上均表现出一致性。     

某大跨度钢桁架桥抗震分析

大跨度多功能的地标性桥梁建筑在城市桥梁建设中频繁出现,其抗震性能的分析计算成为控制设计的主要因素,传统的桥梁结构的抗震设计不考虑固定支座破坏的非线性力学性能,但该假定是不切合工程实际的。以某大跨度钢桁架桥为例,采用MIDAS CIVIL有限元软件,分别采用地震反应谱和非线性时程分析方法,对考虑固定支座破坏与否的情况下桥梁结构的地震反应进行了对比分析,分析表明,考虑支座破坏分析后桥墩水平地震力大大减小,上部钢桁架与桥墩均未屈服,摩擦摆支座位移符合规范要求,非线性时程分析结果更符合工程实际。     

论语言发展的滚动模式与语言规范的基本原则

语言发展的主要内容是语言内部结构某些要素的变化、补充、消失。本文阐述语言发展的“滚动模式” :将语言发展、变化的过程视为滚动前进的球 ,即语言球 ,进而阐述语言球的三个组成部分—基本成分、新生成分、历史成分 ,在此基础上阐述了以语言发展“滚动模式”为理论依据的语言规范三项基本原则     

基于邻域相关性小波去噪的滚动轴承包络解调及故障分类

将邻域相关性的冗余第二代小波应用于滚动轴承信号降噪,用Hilhert包络解调法提取的故障特征频率,比较不 同转速和载荷下的提取效果,提出包络幅值峭度指标,并将其输入BP神经网络进行故障诊断。结果表明：基于邻域相关 性的冗余第二代小波降噪方法能很好的抑制噪声,保留原信号的信息;降噪后的故障信号经过Hilbert包络解调能找到 特征频率及其倍频,其效果优于原始信号的包络解调分析。工况会影响分析效果,且速度对提取效果的影响大于载荷。 包络幅值峭度指标能很好区分不同工况的故障信号,结合BP人工神经网络诊断正确率为100%。     

冷轧生产批量计划与调度问题模型及算法

对冷轧生产系统特点进行分析,将冷轧生产批量计划与调度问题抽象为多阶段、多品种带有中间库的批量计划与调度问题。针对该问题建立了数学模型,通过对库存成本和调整成本惩罚系数的控制可以协调库存水平和调整次数的关系。对所建立的模型,提出了基于二进制粒子群优化与局部搜索的混合求解算法。最后,通过对企业实际生产数据的计算和分析,验证了模型和算法的可行性和有效性。     

A revisitation of the export-led growth hypothesis in Malaysia using the leveraged bootstrap simulation and rolling causality techniques

According to the neoclassical growth theory, export expansion could stimulate economic growth because it promotes specialisation and raises factor productivity. Thus, many developing countries depend heavily on export-orientated businesses to accelerate economic growth. Nevertheless, the causality evidences on the export-led growth hypothesis remain elusive and controversial. Two primary empirical questions emerged in the international trade and development literatures are: (a) Does the export-led growth hypothesis still valid? (b) Why causality evidences are inconsistent among studies? In light of these, the present study attempts to contribute to the export-led growth literature by using the Malaysian data set. This study covers the monthly data set from January 1975 to August 2010. To achieve the objectives of this study, we employ the leveraged bootstrap simulation causality test and also the rolling regression-based causality tests. The leveraged bootstrap simulation causality results suggest that exports and output growth are bilateral causality in nature. However, the rolling causality results demonstrate that the causality inferences for export-led growth hypothesis are unstable over time. For this reason, policy initiative to promote exports may not always stimulate economic growth and development in Malaysia. Therefore, balancing policy is urged to ensure that the economic growth in Malaysia can be materialised.     

Dependence between oil and commodities markets using time-varying Archimedean copulas and effectiveness of hedging strategies

The aim of this work is to study in a first step the dependence between oil and some commodity prices (cotton, rice, wheat, sucre, coffee, and silver) using copula theory, and then in a second step to determine the optimal hedging strategy for oil–commodity portfolio against the risk of negative variation in commodity markets prices. The model is implemented with an AR-GARCH model with innovations that follow t distribution for the marginal distribution and the extreme value copula for the joint distribution and parameters and dependence indices are re-estimated in each new day which allow taking into account nonlinear dependence, tails behavior, and their development over time. Various copula functions are used to model the dependence structure between oil and commodity markets. Empirical results show an increase in the dependence during the last 6 years. Volatility for commodity prices registered record levels in the same time with the increase in uncertainty. Optimal hedging ratio varies over time as a consequence of the change in the dependence structure.     

成本动因合并模型在勘测设计企业的应用研究

选取恰当的成本动因是作业成本法成功实施的关键。基于B勘测设计研究院2013年的成本数据,借助成本动因合并的矩阵模型,选取该院4个具有代表性的勘测设计科研项目进行成本动因和成本动因合并分析,指出成本动因合并的矩阵模型成功降低了勘测设计企业间接成本矩阵的维度,简化了成本分配工作。在此基础上,对勘测设计企业成本动因数量的选择提出完善成本动因维护制度、落实滚动预算、推进企业会计信息化和网络化等建议。     

外径密封式螺旋槽推力轴承

本文提出一种外径密封的螺旋槽推力轴承新结构,并利用螺旋槽近似理论对该轴承进行了分析计算。文中给出了承载能力和刚度公式,同时通过实例论证了该轴承具有远大于普通螺旋槽推力轴承的承载能力和刚度。该种轴承结构为进一步提高空气动压推力轴承的工作性能开辟了新途径。