Urban vans,e-commerce and road freight transport

Abstract

A city will typically depend on at least 150 supply chains and freight is a key part of them. This article aims to explore at the qualitative and qualitative level (1) how e-commerce drives both travel and urban freight transport and (2) to estimate how various manufacturing activities determine the stability of demand for freight transport. The article provides elasticity estimates on (1) the demand for road freight transport for five industry sectors using a time series framework; data on GDP (gross value added) and on fuel costs per t-km (tonne-km). A key finding is that e-commerce induces freight traffic, by vans, but the decline in freight intensity of the economy is only temporary since urban economic activity contributes to growth of freight. Our analysis of five manufacturing sectors confirms that cyclical sectors are more sensitive to energy price gyrations over time than non-cyclical sectors. Price elasticities are high but comparable to other studies. The income elasticity of freight transport is large for the five sectors, but the high heterogeneity of freight sectors means that predicting this activity is challenging. It is observed that truck freight intensity (km of trucks per GVA) declines but not enough to offset the rise in energy needed to fuel the entire freight transport sector; it is likely that the rise in van freight increases the demand for freight energy in urban regions.     

中国特色社会主义整体文明的构建

为了深入认识安徽省农业碳排放与农业经济增长之间的相互关系,并为区域低碳农业发展政策措施的制定提供理论依据,采用Tapio与LMDI模型对安徽省农业碳排放的脱钩效应及影响因素进行研究。结果表明：1998—2014年安徽省农业碳排放总量呈波动上升趋势,具体表现为“快速增长-持续〖JP2〗下降-缓慢上升”三阶段特征;研究期内农业碳排放与农业经济增长间的脱钩关系以弱脱钩和强脱钩为主,说明安徽省农业低碳减排工作取得一定成效;效率因素、劳动力因素和结构因素均对农业碳排放增长具有抑制作用,它们在研究期内的累计减排贡献量分别为896.51万t,341.62万t和253.67万t,〖JP〗而农业经济发展则是碳排放增长的主要驱动因素,其引发的累计碳排放增量高达1552.29万t。     

基于改进型滑模观测器的变频洗衣机用PMSM无位置传感器控制

针对永磁同步电机( PMSM)位置传感器成本高、维护难等问题,设计了一套用于变频洗衣机的PMSM无位置传 感器控制方案。采用改进型滑模观测器(SMO)实现电机转子位置与转速的估算,通过三电阻采样方式来检测三相电流, 有效地降低了系统成本。系统采用矢量控制模式,针对洗衣机负载波动大、运行速度高的特点,在电流内环设计中增加 了电压前馈补偿解耦控制环节,与传统PI调节器相比,该方案能够改善电流跟踪效果,提高控制性能。最后,在洗衣机 样机平台上进行了实验验证,实验结果证明该控制方案运行可靠,控制效果良好,能够满足洗衣机的工作要求。     

Controlling epileptic seizures in a neural mass model

In an effort to understand basic functional mechanisms that can produce epileptic seizures, we introduce some key features in a model of coupled neural populations that enable the generation of seizure-like events and similar dynamics with the ones observed during the route of the epileptic brain towards real seizures. In this model, modified from David and Friston’s neural mass model, an internal feedback mechanism is incorporated to maintain synchronous behavior within normal levels despite elevated coupling. Normal internal feedback quickly regulates an abnormally high coupling between the neural populations, whereas pathological internal feedback can lead to hypersynchronization and the appearance of seizure-like high amplitude oscillations. Feedback decoupling is introduced as a robust seizure control strategy. An external feedback decoupling controller is introduced to maintain normal synchronous behavior. The results from the analysis in this model have an interesting physical interpretation and specific implications for the treatment of epileptic seizures. The proposed model and control scheme are consistent with a variety of recent observations in the human and animal epileptic brain, and with theories from nonlinear systems, adaptive systems, optimization, and neurophysiology.     

When is it time to revise your SKU classification: setting and resetting the decoupling point in a dairy company

Classification of stock-keeping units (SKUs) is a much used approach to determine inventory strategy, production strategy or location of the decoupling point for different SKU categories. However, the literature mainly provides approaches for determining categories at a certain moment in time without addressing the need and factors that urge revision of a determined classification. This paper addresses that gap. The empirical part relies on an extensive case study of a dairy company and uses a large longitudinal data-set from the case company. Our study demonstrates that periodic reclassification is needed to either increase the competitive strength of the company or to reduce risks. Still, classification and reclassification are much more a subtle process that balances customer wishes, operational decisions and commercial motives than a straightforward calculation.     

感应电机解耦控制智能PSD调速系统研究

本文针对感应电动机解耦控制,采用单神经元ＰＳＤ算法作速度调节器的磁链调节器,构成感应电动机ＰＳＤ调速系统。该系统自适应学习能力强,仿真研究表明,控制效果良好。     

脱耦中的合法性动员——对南方某大学孵化器的扎根理论分析

脱耦与合法性重建是组织社会学研究的核心和中国科技孵化器建设事业的重点。已有研究对组织特性和可利用的社会、文化资源的强调,并不能完满地解释中国大学孵化器脱耦中的合法性动员机制。本文通过对南方某成功运作的大学孵化器的扎根理论分析发现,当面对强大的环境神话压力时,无法实现经济效率的初创期组织必须首先完成合法性重建,才能进行正式的制度化。该孵化器成功的关键在于,首先移植已形成特殊信任的校友网络实现道义合法性,再进一步抓住现实机遇,借助项目的成功实现实用合法性。唯一权威领导的塑造和“四不像”模糊制度理念的宣导等都是重建中重要的意义建构的部分,这也离不开与更大的制度场域的重新耦合。     

客户隐性知识对延迟策略实施的影响及其获取方法研究

客户隐性知识能否被有效获取是影响延迟策略实施的一个关键因素。探讨了延迟生产系统知识管理的必要性,总结了传统制造模式和延迟策略实施模式下生产系统管理的区别,提出了延迟策略实施过程中知识管理的运行机理。实证分析表明,基于事例推理的客户隐性知识的获取对实施延迟策略生产系统具有重要的作用。     

安徽省经济发展与碳排放脱钩研究

促进经济发展和环境协调是城市走可持续发展之路的本质要求.基于Tapio脱钩模型,对安徽省2001-2011年经济发展与碳排放进行脱钩实证研究.通过计算脱钩弹性指数发现：2001年为强负脱钩;2002、2003和2006年脱钩弹性＞1.2,为扩张负脱钩;2007年改变为扩张连结;其余年份则为弱脱钩.表明安徽省经济系统正处于弱可持续发展状态,走低碳经济之路任重道远.     

双层博弈视角下中美经贸摩擦走势及应对策略分析

特朗普政府执政后,中美贸易摩擦演变为对华科技、政治军事、教育文化等各个领域的“ 脱 钩”,拜登上台后基本延续特朗普政府的对华政策。此次美国对华“脱钩” 与以往小范围经贸摩擦不同, 其根本原因在于:美国对华政策转向、大国地位周期性变化、反全球化运动及民粹运动兴起和防范中国抓 住第四次工业革命的历史机遇。在美国对华“脱钩” 根本原因发生变化的背景下,双方博弈的初始条件 与以往有很大区别,有必要基于新的背景和现实条件科学动态地判断中美经贸摩擦走向和中国的最优应 对策略。本文试图在双层博弈理论的指导下分析上述问题。在信息不完全假设下,建立一个双层动态博 弈模型,并以此模型为分析框架,判断中美博弈的可能走向;以及在动态博弈环境中,中国在中短期和长 期内的不同应对策略。中短期内,美国遏制中国高质量发展权利的目标价值不会变化,中国需在精准回 击的同时,减少对美国市场和技术的依赖,进一步打破传统发展路径依赖,依靠科技创新发展国家竞争 力,加快形成国内国际“双循环”发展格局。长期来看,当美国自身经济受到“ 脱钩” 的影响时,美国国内 反对“脱钩”声音壮大,美国遏制中国高质量发展权利的目标价值变化,中方需根据美国“脱钩”政策变化 实时调整应对方案。