Supply chain focus dependent safety stock placement

Increasing globalization, growing product range diversity, and rising consumer awareness are making markets highly competitive, forcing supply chains to adapt constantly to different stimuli. Growing competition between supply chains (as well as players within them) is also warranting a priority for overall supply chain performance over the goals of individual players. It is now well established in the literature that, among the many order winners, both overall supply chain cost and responsiveness (i.e., supply chain lead time) are the most significant determinants of supply chain competitiveness. The literature, however, mostly focuses on supply chain cost minimization with rather simplistic treatment of responsiveness. By introducing the concept of a coefficient of inverse responsiveness (CIR), we facilitate efficient introduction of responsiveness related costs into the scheme of supply chain (SC) performance evaluation and/or optimization. Thus, our model aids supply chain managers in achieving better strategic fit between individual business unit strategies and overall supply chain requirements in terms of cost efficiency and responsiveness. In particular, it aids in strategic placement of safety stocks at different stages in the supply chain. Our model also offers managerial insights that help improve our intuitions into supply chain dynamics. The model is more suited for strategic SC alignment, for example, when dealing with product changeovers or introduction of new product, rather than for operational control.     

三相反应式步进电动机的高性能驱动电源

提出了一种可变细分的高性能步进电动机驱动电源,该电源用于驱动三相反应式步进电动机。细分波形由AT89S52单片机控制DAC0832数/模转换器产生,驱动单元采用高压型恒流斩波电路。该电源在控制步进电动机转动时,微步精度高,低速运转时电动机振荡小,高速运转时输出力矩大。通过选择合适的细分数,可与不同档次的CNC控制器配套使用。批量使用结果表明,该电源稳定性好、性价比高,具有一定的推广使用价值。     

Life cycle implications of product modular architectures in closed-loop supply chains

Most of the product life cycle costs and environmental impacts are determined during product design stage. A product supply chain network can be seen as a system dealing with product life cycle processes. Ideally, a product should be designed to have a structure yielding a good life cycle performance in its existing supply chain network. However, there is a lack of research related to modeling supply chain effects in the product design stage. This paper aims at investigating the supply chain effects on product modular design. The life cycle performance of a modular structure (life cycle cost and life cycle environmental impact) at various supply chain states is evaluated by a supply chain evaluation model and analyzed by statistical techniques. The preliminary results indicate that the supply chain-related effects on product life cycle performance are significant and modular structure optimization is effective in reducing the surge of life cycle cost and life cycle environmental impact caused by various supply chain states. The main supply chain effects are identified for use in product design improvement.     

Using Artificial Neural Networks for Energy Regulation Based Variable-speed Electrohydraulic Drive

In the energy regulation based varibable-speed electrohydraulic drive system, the supply energy and the demanded energy, which will affect the control performance greatly, are crucial. However, they are hard to be obtained via conventional methods for some reasons. This paper tries to a new route: the definitive numerical values of the supply energy and the demanded energy are not required, except for their relationship which is called energy state. A three-layer back propagation(BP) neural network was built up to act as an energy analysis unit to deduce the energy state. The neural network has three inputs: the reference displacement, the actual displacement of cylinder rod and the system flowrate supply. The output of the neural network is energy state. A Chebyshev type II filter was designed to calculate the cylinder speed for the estimation of system flowrate supply. The training and testing samples of neural network were collected by the system accurate simulation model. After off-line training, the neural network was tested by the testing data. And the testing result demonstrates that the designed neural network was successful. Then, the neural network acts as the energy analysis unit in real-time experiments of cylinder position control, where it works efficiently under square-wave and sine-wave reference displacement. The experimental results validate its feasibility and adaptability. Only a position sensor and some pressure sensors, which are cheap and have quick dynamic response, are necessary for the system control. And the neural network plays the role of identifying the energy state.     

数字同步网在铁路通信系统中的应用

对同步网的基本概念、同步方式及综合定时供给系统(BITS)进行了介绍,并阐述了数字同步网在本地区的应用情况.随着通信网络的不断发展,为了适应现代通信网同步的性能越来越高,所需要的基准定时信号的数量和类型也不断增多,数字同步网应用而生,从而调节通信网中的时钟以建立并保持同步,满足通信网传递业务信息所需的传输和交换性能要求,它是保证网络定时性能的关键.     

制造商主导下的不同双渠道零售商渠道定价策略与渠道选择

在制造商主导的双渠道供应链结构中,引入价格弹性系数、单位直销成本和佣金比例系数建立模型,运用博弈论分析了双渠道零售商的最优定价策略与渠道选择问题.研究发现,零售商利润受网上直销成本和消费者渠道偏好的共同影响,当两者均较低时,网络直销结构下利润最高;当前者较高而后者较低时,网络分销结构下利润最高;当两者均较高时,网络代销...     

A new model of the antifriction effect on wiredrawing with ultrasound

In this paper, two different evolutionary algorithm-based neural network models were developed to optimise the unit production cost. The hybrid neural network models are, namely, genetic algorithm-based neural network (GA-NN) model and particle swarm optimization-based neural network (PSO-NN) model. These hybrid neural network models were used to find the optimal cutting conditions of Ti[C,N] mixed alumina-based ceramic cutting tool (CC650) and SiC whisker-reinforced alumina-based ceramic cutting tool (CC670) on machining glass fibre-reinforced plastic (GFRP) composite. The objective considered was the minimization of unit production cost subjected to various machine constraints. An orthogonal design and analysis of variance was employed to determine the effective cutting parameters on the tool life. Neural network helps obtain a fairly accurate prediction, even when enough and adequate information is not available. The GA-NN and PSO-NN models were compared for their performance. Optimal cutting conditions obtained with the PSO-NN model are the best possible compromise compared with the GA-NN model during machining GFRP composite using alumina cutting tool. This model also proved that neural networks are capable of reducing uncertainties related to the optimization and estimation of unit production cost.     

高集成综合传输网络设计

为配合雷达的高机动性,需通过优化布局,实现天线阵面厚度的超薄设计。传统阵面微波系统没有从系统层面统筹设计,各模块功能独立,用电缆连接,无法实现高集成度。文中结合阵面的功能需求,对综合传输网络的结构和互连方案进行优化设计。结果表明:通过射频、光纤、电源网络一体化设计和行列互联设计,可以实现优化性能、高集成、超薄阵面对阵面微波系统的要求。     

三相反应式步进电机的高性能驱动电源

提出了一种可变细分的高性能步进电机驱动电源，该电源用于驱动三相反应式步进电机。细分波形由AT89S52单片机控制DAC0832数／模转换器产生，驱动单元采用高压型恒流斩波电路。该电源在控制步进电机转动时，微步精度高，低速运转时电机振荡小，高速运转时输出力矩大。通过选择合适的细分数，可与不同档次的CNC控制器配套使用。批量使用结果表明，该电源稳定性好、性价比高，具有一定的推广使用价值。     

面向服务悖论规避的制造企业服务衍生状态判定

针对制造企业服务衍生可能出现"服务悖论"而出现服务转型失败的问题,在考虑产品主导逻辑与服务主导逻辑下制造企业成本和绩效关系的基础上,构建了两种主导逻辑下的供需价值创造模型,旨在探究两种主导逻辑下制造企业价值创造机理以及服务衍生对企业绩效影响的内在规律.研究表明,制造企业采取服务主导逻辑未必能够实现供需价值的更大创造,而...     

汽车发动机性能试验台监控系统设计

介绍了由RS485总线组成的分布式汽车发动机性能参数测试系统的设计。对组成该系统的现场采集单元、通信网络单元、系统管理单元进行了分析与阐述。经现场实验验证,该分布式测控系统具有数据测量准确可靠,可扩展性强,性价比高,维护方便等特点。     

Hybrid approach to distribution planning reflecting a stochastic supply chain

Today’s business environment is experiencing as a period of expansion and the globalization. Therefore, a distribution plan with low cost and high customer satisfaction in supply chain management (SCM) has been widely investigated. The purpose of this study is to establish optimal distribution planning in the supply chain. In this paper, a hybrid approach involving a genetic algorithm (GA) and simulation is presented to solve this problem. The GA is employed in order to quickly generate feasible distribution sequences. Considering uncertain factors such as queuing, breakdowns and repairing time in the supply chain, the simulation is used to minimize completion time for the distribution plan. The computational results for an example of a simple supply chain are given and discussed to validate the proposed approach. We obtained a more realistic distribution plan with optimal completion time by performing the iterative hybrid GA simulation procedure which reflects the stochastic nature of supply chains.     

Creating agile supply chains

An agile business needs an agile supply chain. Quick response to customer demand, the ability to customise and the need to provide multiple variants for profitable customer niches are all increasingly required by many companies. Yet as manufacturers inexorably move their sourcing of components and low value-added operations offshore, to lower cost countries, so their supply chains increase in both distance and complexity. Many companies are faced with the challenge of providing an agile response to customers and yet operating a lean operation across an extended global supply chain. This is a challenge that needs a solution beyond the abilities of simply judgement, the telephone and spreadsheets. Companies need to utilise the power of Internet-enabled software to provide visibility across their global supply chain and to help them optimise it. In particular the new generation of supply chain optimisation software offers companies the ability to gain visibility and optimisation across their supply chains, at significantly reduced ownership costs compared to earlier systems     

多级笼式套筒减压阀的设计及阀口流量特性研究

我国船舶蒸汽动力系统汽轮给水泵组属于小容量机组,所配置的再循环阀能保护给水泵在小流量工况下的安全性,但同时存在小流量工况时给水泵振动噪声显著放大的现象。因此需设置一联动的回水调节阀门,在给水调节阀开度较小的工况下,通过打开联动的回水阀提高回水量,降低给水泵机组以及再循环阀运行振动噪声。针对回水调节阀的多级笼式套筒减压阀口进行研究,利用FLUENT流体计算仿真软件对不同开度时阀口的流量特性进行了数值模拟,并通过试验对阀口的流量特性进行了验证。研究结果表明,多级笼式套筒减压结构使回水调节阀自身具有低噪声性能,可有效改善给水泵机组的运行工况。     

基于三前馈APIOBPCS的供应链弹性与运作成本评估

为兼顾供应链系统的弹性和运作成本,提出三前馈自动渠道的、基于库存和定购的生产控制系统(Triple feed-forward automatic pipeline, inventory and order-based production control system, TFF-APIOBPCS)。在自动渠道的、基于库存和定购的生产控制系统模型中,增加一阶微分前馈环节,以部分抵消需求波动对库存的影响。在零稳态误差情况下针对生产控制系统的不同极点分布,分析一阶微分前馈环节的参数与供应链弹性的关系。综合考虑库存成本及生产调节成本,构造供应链系统的运作成本模型。通过阶跃需求、随机需求下的供应链系统仿真,评估一阶前馈环节参数对供应链弹性及运作成本的影响,验证三前馈自动渠道的、基于库存和定购的生产控制系统的有效性。结果表明,针对不同波动程度的需求,合理设置一阶微分前馈环节的参数,可以获得弹性与运作成本的良好均衡。     

Capacities-based supply chain network design considering demand uncertainty using two-stage stochastic programming

The design of a supply chain (SC) aims to minimize cost so the product can reach the customer at the cheapest cost with flexible demand. The demand of a product is variable with time and environment. Most of the researchers have considered investment cost, processing cost, and transportation cost as variable costs to minimize the cost while considering a constant demand. In actual practice, the demands are flexible. In this paper, a two-stage stochastic programming model has been proposed for a capacities-based network design of a supply chain for flexible demands while considering inventory carrying cost and missed opportunity cost in addition to the above-mentioned costs. It will enhance the logistic planning and seek the location network optimally. Furthermore, in the first stage, decision variables represent different nodes (facility locations of echelons) of the supply chain, with the assumption that they will be considered at the design stage before uncertain parameters are unveiled. On the other hand, decision variables related to the amount of products to be produced and stored in the nodes of the SC, the flows of materials among the entities of the network, and shortfalls and excess at the customer centers are considered as second-stage variables. The methodology has been illustrated by solving an example. It was found that the proposed model yields more feasible and advantageous results.     

A novel hybrid method for supply chain optimization with capacity constraint and shipping option

In a modern market, supply chain network design is considered as a strategic decision that provides the proper platform for cost management and increases the competitive edge of enterprise. In a five-tier supply chain, there are several facilities such as suppliers, manufacturers, warehouses, distribution centers, and retailers or customers. For product transportation from one facility to another, different types of options may be used. These options have variety price and the manager should do the best assignment to reduce the total cost. In this paper, we formulated an integer programming model for a five-tier supply chain with capacitated facility and multiple transportation option with fixed lead time. We also proposed a novel meta-heuristic solution methodology that combines the Taguchi's feature with artificial immune approach in order to solve the proposed model. The performance of the proposed solution methodology has been examined against a set of numeric instances and the obtained results are compared with those provided by hybrid genetic algorithm and Taguchi and artificial immune system. Results indicate that this methodology can make better results than previous solutions effectively.     

Design and analysis of flow measurement of conductive liquid and transmission via optical channel

Measurement and transmission of flow rate of a conducting liquid through a pipe line is generally done by using electromagnetic flow meter which consists of a large electromagnet and a pair of sensing electrodes along with electronic system and involves large cost and size. In the present paper, a very simple flow sensing system for a conducting liquid is proposed and this system does not require any electromagnet and involves very low cost. Moreover in modern instrumentation system the signal transmission through optical communication system is being more preferred where the transmitted signal does not suffer from measurement error due to electromagnetic interference. So an MZI based optical communication technique has been described in the present paper. The proposed technique consists of only four insulated conducting electrodes in contact with the flowing liquid along with an electro-optic system for signal conditioning and transmission of the measured signal to a remote location. The performance of the sensor and the transmission system has been analyzed in the form of a bridge network with bridge arms represented by lumped parameter polarization impedances among the electrodes. The theoretical equations explaining the operation of the bridge network with a stabilized sinusoidal ac source and MZI based electro-optic system have been derived. A proto type unit has been designed, fabricated and its function has been studied experimentally and the experimental results are reported in the paper. A very good linear characteristic under streamline condition of the proposed unit has been observed with very good repeatability and very small uncertainty of measurement. The graphical abstract is shown below.     

基于低压电力载波通信的温度采集系统

低压电力载波通信借助完善的电力线网络作为数据传输媒介,可以极大地降低通信线路布线成本,另外,扩频通信技术的应用使低压电力载波数据传输在抗干扰、抗衰减、可靠性等各项能力上都有了极大的提高。介绍了利用该项通信技术构建的温度采集系统,系统主要由终端温度采集模块、集中器和上位PC机3个部分组成,终端温度采集模块与集中器之间通过电力线传输数据,集中器与PC通过串行通信传输数据,文中主要讨论电力载波数据通信部分。     

Design and modeling of an intelligent temperature to frequency converter

This paper presents the development of an intelligent temperature to frequency converter to measure the temperature using a negative temperature coefficient (NTC) thermistor. The signal conditioning circuit (SCC) of the NTC thermistor is a modified timer circuit whose control voltage is generated by a difference amplifier. The thermistor SCC acts as a temperature to frequency converter and exhibits a moderate linear temperature-frequency characteristic over a range of 0–100 °C with a linearity error of ±3.5%. A multilayer perceptron (MLP) neural network with Levenberg–Marquardt (LM) algorithm is used for modeling and nonlinearity estimation of the converter. The LM algorithm effectively reduces the linearity error as compared to the Broyden–Fletcher–Goldfarb–Shanno (BFGS) and the scaled conjugate gradient (SCG) algorithms. Mean square error (MSE), regression coefficients, linearity, accuracy and dispersion spread are used to evaluate the performance of the proposed ANN-based modeling. The intelligence of the ANN-based modeling is embedded in a low cost microcontroller unit and the performance is experimentally verified on a prototype unit. The linearity error and sensitivity of the proposed unit are approximately ±0.35% and 5 kHz/°C respectively.