动态视角下城市通勤路径优化研究

针对城市上班族“通勤难”的问题,考虑到交通拥堵发生的不确定性,以动态视角研究基于实时交通信息的通勤车动态路径优化问题,同时将停靠点选址问题作为其影响因素优先进行分析。建立以行驶路径最短为目标的初始路径优化模型,并重新制定路线更新规则,将路口交叉点作为新的关键点引入更新策略。通过实证分析得到,动态优化后无拥堵状态下的通勤效率可以提高35.7%,存在拥堵的状态下通勤效率可以提高40%,证明了模型和算法的有效性。     

A mathematical model for vehicle routing problem under endogenous uncertainty

In this study, a multistage stochastic programming (SP) model is presented for a variant of single-vehicle routing problem with stochastic demands from a dynamic viewpoint. It is assumed that the actual demand of a customer becomes known only when the customer is visited. This problem falls into the category of SP with endogenous uncertainty and hence, the scenario tree is decision-dependent. Therefore, nonanticipativity of decisions is ensured by conditional constraints making up a large portion of total constraints. Thus, a novel approach is proposed that considerably reduces the problem size without any effect on the solution space. Computational results on some test problems are reported.     

初始几何缺陷模式对单层球面网壳抗震性能的影响

为探索地震作用下单层网壳的最不利初始几何缺陷分布模式,对施加四种初始几何缺陷的单层球面网壳分别开展了抗震性能研究.参照相关文献选取一致缺陷模态一、一致缺陷模态二,特征值缺陷及一阶振型缺陷四种典型的初始几何缺陷分布模式,并介绍了四种初始几何缺陷模式的理论计算公式及施加于理想网壳的方法;通过有限元建模分析,考察了施加四种初...     

Impact of visual performance management systems on the performance management practices of organisations

The purpose of this paper was to explore how visual strategy and performance management techniques impact performance measurement and management practices of organisations. A novel visual performance management approach is developed and implemented in qualitative case studies with seven manufacturing SMEs across Europe. The implementation cases demonstrate that visual management systems serve to support ongoing strategy development and implementation, facilitate performance measurement and review, enable people engagement, improve internal and external communication, enhance collaboration and integration, support the development of a continuous improvement culture and foster innovation. Additional explorative and longitudinal research is required to understand the long-term impact of such approaches in both small and larger organisations.     

钻孔数对复合式地源热泵系统运行策略及能耗的影响

以湿球温度控制法作为郑州某建筑复合式地源热泵系统控制策略,建立基于TRNSYS的地源热泵系统及其控制系统的模拟平台。在相同钻孔数下模拟不同湿球温度设定值下的系统运行特性,并获取不同钻孔数下维持土壤热平衡的湿球温度设定值。模拟结果表明,钻孔数对湿球温度控制法的湿球温度设定值影响不大,系统的能耗随钻孔数的增加逐渐降低。     

基于参数组合和加速度传递函数的最优MTMD研究

多重调谐质量阻尼器（MTMD）是由许多频率成线性分布的调谐质量阻尼器组成。可能的系统参数组合形成5种MTMD,即MTMD－1－MTMD－5。基于具有一般MTMD时结构的加速度传递函数,建立了MTMD－1－MTMD－5加速度动力放大系数（ADMF）的统一模式。利用ADMF和数值搜寻技术对MTMD－1－MTMD－5进行了参数研究。参数包括：频率间隔、阻尼比、调谐频率比和总数。为了比较亦给出了TMD的数值结果。大量的数值比较表明：在工程应用中,应优先选择MTMD－1。     

纸杯机典型机构的运动分析及仿真

纸杯机工作过程主要由曲柄摇杆机构完成,为确保其工作可靠和运动平稳,采用理论推导和数值模拟相结合的方法,对其典型机构进行了运动分析,建立了数学模型.分析了滑块的位移、速度及加速度,计算结果与实测值相吻合,证明了数学模型的正确性.并采用运动分析软件分析了纸杯加工组合机构的运动与动态特性,绘制了速度、加速度曲线,为纸杯机设计与改进提供了重要的数据.     

板式换热器板型尺寸对换热性能影响的探讨

本文介绍了板式换热器的常用板片结构和特点以及设计选用时需要考虑因素，分析了板片的波纹形式及几何参数对换热性能的影响，并通过实例对特定条件板型尺寸对板片换热性能的影响进行了分析比较。     

国外技术性贸易措施对我国儿童玩具出口的影响及标准化应对策略

本文介绍了我国儿童玩具行业的发展现状,分析了我国儿童玩具产品出口面临的主要技术性贸易壁垒及其影响,从标准化战略、检验机构互认、WTO/TBT-SPS通报评议等方面,提出了技术性贸易措施的标准化应对策略.     

A study on investments in the big data-driven supply chain,performance measures and organisational performance in Indian retail 4.0 context

The use of digital technologies such as ‘internet of things’ and ‘big data analytics’ have transformed the traditional retail supply chains into data-driven retail supply chains referred to as ‘Retail 4.0.’ These big data-driven retail supply chains have the advantage of providing superior products and services and enhance the customers shopping experience. The retailing industry in India is highly competitive and eager to transform into the environment of retail 4.0. The literature on big data in the supply chain has mainly focused on the applications in manufacturing industries and therefore needs to be further investigated on how the big data-driven retail supply chains influence the supply chain performance. Therefore, this study investigates how the retailing 4.0 context in India is influencing the existing supply chain performance measures and what effect it has on the organisational performance. The findings of the study provide valuable insights for retail supply chain practitioners on planning BDA investments. Based on a survey of 380 respondents selected from retail organisations in India, this study uses governance structure as the moderating variable. Implications for managers and future research possibilities are presented.     

鳍条运动模式对仿生波动鳍推进力影响的研究

仿生波动鳍的鳍条运动模式分为等幅和变幅两种类型,通过实验发现这2种鳍条运动模式下所产生的游动性能存在着较大的差异.为了揭示这种差异存在的内在缘由,建立基于鳍条这2种运动模式的仿生波动鳍运动学方程.利用计算流体动力学原理,比较不同运动学参数下2种运动模式鳍面压力分布情况,分别给出2种模式下波动鳍产生的无量纲阻力系数随时间的变化情况以及无量纲阻力系数时间平均值随频率、摆幅和波长的变化规律,给出鱼鳍模型中部沿鳍条方向切面的速度场和压力场.结果表明:2种模式下产生的推进力均随频率、摆幅和波长的增大而增加,但等幅摆动产生的推进力始终小于变幅摆动;2种模式下模型中部切面的速度场和压力场存在明显的差异,而尾迹二维涡量场结构和分布形态十分相似,说明影响2种模式游动效果的主要原因之一来自于沿鳍条方向的差异.结论进一步阐述了依赖鱼鳍波动推进的水生生物体高效游动的本质,也为研制高性能的仿鱼鳍波动推进装置提供了参考.     

The impacts of asset impairments on performance in the Taiwan listed electronics industry

This paper explores whether the recognition of asset impairments provides an opportunity for earnings management by examining changes in the performance. First, we apply a dynamic data envelopment analysis model to evaluate the operating performance of Taiwanese electronics firms for the period from 2004 to 2013. Statistical tests are next applied to assess the average efficiency variation between the periods before and after firms recognise asset impairments. Several empirical findings are as follows: managers recognise asset impairments when their firms have poor performance as compared to other firms that do not record any asset impairments recognition, and that their performance keeps on improving in both the year of recognising asset impairments and the year after asset impairments recognition. That is, managers tend to recognise asset impairments to improve operating performance, while the firms are performing poorly, supporting the opportunistic behaviour theory.     

An efficient numerical method for analyzing the thermal effects on the vibration of embedded single-walled carbon nanotubes based on the nonlocal shell model

Employing the variational differential quadrature (VDQ) method, the effects of initial thermal loading on the vibrational behavior of embedded single-walled carbon nanotubes (SWCNTs) based on the nonlocal shell model are studied. According to the first-order shear deformation theory and considering Eringen's nonlocal elasticity theory, the energy functionality of the system is presented and discretized using the VDQ method. The effects of thermal loading and elastic foundation are simultaneously taken into account. The use of the numerical discretization technique in the context of variational formulation reduces the order of differentiation in the governing equations and consequently improves the convergence rate. The accuracy of the present model is first checked by comparison with molecular dynamics simulation results and those of other methods. The effects of involved parameters are then investigated on the fundamental frequencies of thermally preloaded embedded SWCNTs. The results imply that the thermal loading has a significant effect on the vibration analysis of embedded SWCNTs.     

基于动态性能空间的优化控制方法设计

相同零点、极点在根轨迹平面的不同位置表现出不同的动态性能,表明系统性能与零点或极点本身无关,完全由其所处的位置决定。从经典控制理论的根轨迹平面出发,借助数理分析中的“场论”概念,以定位精度和控制稳定性作为系统动态性能的描述量,尝试建立动态性能指标与根轨迹平面坐标之间的函数对应关系;并据此通过在根轨迹平面绘制等振荡线和等精度线,实现动态性能空间的构建。应用该动态性能空间,对六阶线性跟踪系统的实数极点和复共轭零点、极点进行全局优化。灵敏度、补灵敏度函数及动态响应结果显示：该优化设计方法可以较好地解决系统定位精度与控制稳定性之间的矛盾,满足精确动态跟踪要求,效果远优于P ID控制器。     

Experimental investigation on the train-induced subsidence prediction model of Beiluhe permafrost subgrade along the Qinghai-Tibet Railway in China

Based on dynamic triaxial test at low temperature of the frozen clay from the Beiluhe permafrost subgrade along the Qinghai-Tibet Railway (QTR), residual deformation laws and dynamic subsidence prediction model of permafrost subgrade under train traffic were studied. First, time history curves of residual strain of frozen soil are obtained and analyzed under different temperatures, frequency, confining pressure and moisture content. And conclusions can be drawn that the axial strain rate is greatly affected by the amplitude of dynamic stress, as well as increases with dynamic to static stress ratio and temperature rising, while it decreases with the raise of frequency and moisture content. Hereby, the power functions were adopted to fit the relationships of axial dynamic strain rate vs. stress ratio, temperature, frequency, and moisture content, respectively. Simultaneously, the permafrost dynamic subsidence mechanism was interpreted rationally and the variation of fitting parameters was discussed. Furthermore, the long-term traffic loading subsidence model was established through observing the axis residual strain time histories of frozen specimens under the longtime cyclic loading and adopting the amendment of vibratory number of times. The model can comprehensively consider the effects of stress state, temperature, moisture content, and confining pressure of frozen soil, as well as the vibratory frequency and vibration number of longtime cyclic loading. Consequently, the model can be applied to the train-induced subsidence forecast investigation of permafrost subgrade. The paper has an important significance for rational safety evaluation on long-term operation of permafrost regions railway such as QTR. Meanwhile, the investigation provides basic data for the further research on dynamic damage constitutive model of frozen soil under train traffic and the gradual improvement of railroading criterion in cold regions.     

Chemical process dynamic optimization based on the differential evolution algorithm with an adaptive scheduling mutation strategy

To solve chemical process dynamic optimization problems, a differential evolution algorithm integrated with adaptive scheduling mutation strategy (ASDE) is proposed. According to the evolution feedback information, ASDE, with adaptive control parameters, adopts the round-robin scheduling algorithm to adaptively schedule different mutation strategies. By employing an adaptive mutation strategy and control parameters, the real-time optimal control parameters and mutation strategy are obtained to improve the optimization performance. The performance of ASDE is evaluated using a suite of 14 benchmark functions. The results demonstrate that ASDE performs better than four conventional differential evolution (DE) algorithm variants with different mutation strategies, and that the whole performance of ASDE is equivalent to a self-adaptive DE algorithm variant and better than five conventional DE algorithm variants. Furthermore, ASDE was applied to solve a typical dynamic optimization problem of a chemical process. The obtained results indicate that ASDE is a feasible and competitive optimizer for this kind of problem.     

A study on the systematic framework to develop effective diagnosis procedures of nuclear power plants

In complex systems such as the nuclear and chemical industry, the importance of a diagnosis procedure has been well recognized, since identifying the nature of an on-going event should be preceded to determine successful countermeasures or remedial actions. Unfortunately, a systematic framework that can suggest a unified and consistent process for constructing useful diagnosis procedures seems to be scant.In this paper, the systematic framework that can provide a sound way in constructing a diagnosis procedure is suggested based on two kinds of technical bases, such as the decision-making strategies of human and the test sequencing technique. To demonstrate the appropriateness of suggested framework, the diagnosis procedure of the reference nuclear power plant is reformed based on it. Subjective ratings are conducted to compare reformed procedure with the original one, and results support that operators' performance in an event diagnosis could be improved. Thus, although well designed experiments are needed to draw a reliable conclusion, it is expected that suggested framework could be applied to provide a consistent process in constructing useful diagnosis procedures.     

低温供气条件下新型切向小孔气体轴承动特性的实验研究

针对一种新型切向小孔供气轴承进行了低温供气下的动特性实验,实验中得出了轴承的温降曲线,测定了轴承温度由常温降至低温时轴承间隙的变化,比较了常,低温供气时轴承稳定性的差别。     

The impact of lean methods and tools on the operational performance of manufacturing organisations

Evidence suggests that lean methods and tools have helped manufacturing organisations to improve their operations and processes. However, the real effect of these methods and tools on contemporary measures of operational performance, i.e. cost, speed, dependability, quality and flexibility, is still unclear. This paper investigates the impact of five essential lean methods, i.e. JIT, autonomation, kaizen, total productive maintenance (TPM) and value stream mapping (VSM), on these measures. A linear regression analysis modelled the correlation and impact of these lean practices on the operational performance of 140 manufacturing organisations around the world. In addition, structural equation modelling (SME) was used to cross verify the findings of the regression and correlation analyses. The results indicate that JIT and automation have the strongest significance on operational performance while kaizen, TPM and VSM seem to have a lesser, or even negative, effect on it. This paper provides further evidence regarding the effects that lean practices have on the performance of organisations and thus the research offers companies, and their managers, a better understanding of the relationship between the lean strategy and the performance of their operations.     

A technical note on the dynamic nonstationary inventory-pricing control model with lost sale

This paper studies a non-stationary, periodic review and finite horizon dynamic inventory-pricing problem with lost sale. The existing research on this problem suffers from a lack of concavity. Thus, strong conditions have to be assumed to obtain the optimal policy, i.e. stationary system and additive demand. This paper uses multiplicative demand model, which significantly outperforms the additive demand models from statistical prediction accuracy prospect. We establish the concavity which results in the optimality of Base Stock List Price (BSLP) policy. The conditions for the concavity can be satisfied by many commonly used convex demand and distributions in the literature. Our results complement the existing research for the non-stationary lost sale models in this area.