A mathematical model and a heuristic approach for design of the hybrid manufacturing systems to facilitate one-piece flow

One-piece flow is a design rule that entails production in manufacturing cells on a ‘make one, check one, and move-on one’ basis (Black, J.T., 2007. Design rules for implementing Toyota Production System. International Journal of Production Research, 45 (16), 3639–3664), which reduces manufacturing lead time significantly. This paper proposes a sequential methodology comprised of a mathematical model and a heuristic approach (HA) for the design of a hybrid cellular manufacturing system (HMS), to facilitate one-piece flow practice. The mathematical model is employed in the cases of small- and medium-sized problems, and it attempts to minimise the total number of exceptional operations, while considering machine capacities and alternative machines. The machine-part matrix achieved by the mathematical model is input into the flow line design stage of the HA, where backflow within the cells is eliminated. However, for industrial problems, the proposed HA is utilised. After the formation of the cells by clustering, the HA attempts to eliminate exceptional operations of a given cellular configuration together with a functional structure by employing alternative machines, based on the decision rules developed. Later, unidirectional flow within the cells is achieved and the capacity and budget constraints are satisfied. A medium-sized problem is solved by using both of the approaches, namely, the model integrated with the flow-line design stage of the HA and the complete HA. The results are discussed and the limitations are explained.     

A simplified time-domain design and implementation of cascaded PI-sliding mode controller for dc–dc converters used in off-grid photovoltaic applications with field test results

A time-domain design methodology for voltage regulation control of dc–dc boost and buck-boost converters based on a multi-loop controller with PI regulator for the outer loop and an inner loop with sliding mode current controller has been developed for renewable energy applications such as photovoltaic (PV)-fed dc–dc converters. This paper proposes a new method for the design of PI regulators in such multi-loop control scheme. The proposed design presents a simple analytical method for selecting controller gains and has been validated by simulation as well as hardware implementation. Also, this paper presents an illustrative example based on the proposed design for the voltage regulation control of PV-fed boost converters for off-grid applications. The simulation results for varying irradiation, temperature and load along with stability analysis have been presented in this paper. The proposed controller is implemented in hardware for a 1.1 kW PV-array-fed boost converter. Performance analysis based on field test results using real-time weather data validates the proposed design. Therefore the proposed controller could be considered as an attractive solution for off-grid renewable energy applications like PV- or fuel-cell-fed dc–dc converter, where the variations are stochastic in nature.     

A phase I multi-modelling approach for profile monitoring of signal data

Many industrial processes exhibit multiple in-control signatures, where signal data vary over time without affecting the final product quality. They are known as multimode processes. With regard to profile monitoring methodologies, the existence of multiple in-control patterns entails the study and development of novel monitoring schemes. We propose a method based on coupling curve classification and monitoring that inherits the so-called ‘multi-modelling framework’. The goal is to design a monitoring tool that is able to automatically adapt the control chart parameters to the current operating mode. The proposed approach allows assessing which mode new data belong to before applying a control chart to determine if they are actually in control or not. Contrary to mainstream multi-modelling techniques, we propose extending the classification step to include a novelty detection capability, in order to deal with the possible occurrence of in-control operating modes during the design phase that were not observed previously. The functional data depth paradigm is proposed to design both the curve classification and the novelty detection algorithm. A simulation study is presented to demonstrate the performances of the proposed methodology, which is compared against benchmark methods. A real case study is presented too, which consists of a multimode end-milling process, where different operating conditions yield different cutting force profile patterns.     

Detection and classification mean-shifts in multi-attribute processes by artificial neural networks

To monitor the quality of a multi-attribute process, some issues arise. One of them being the occurrence of a high number of false alarms (type I error) and the other an increase in the probability of not detecting defects when the process is monitored by a set of independent uni-attribute control charts. In this paper, based upon the artificial neural network capabilities we develop a new methodology to overcome this problem. We design a perceptron neural network to monitor either the proportions of several types of product nonconformities (instead of using several np charts) or the number of different types of defects (instead of using several c charts) in a product. Moreover, while the proposed method possesses the ability to be applied for small sample sizes, it is also able to diagnose the mean shift online. We present two simulation experiments in which the proportions of several types of nonconformities are monitored. In addition, we present one more simulation experiment in which the number of different types of defect is controlled. We also compare the performance of the proposed methodology with the ones from the Mnp and T ² charts for multi-attribute processes. The results of the simulation studies are encouraging.     

可供性视域下博物馆非遗虚拟仿真系统设计研究

目的 探究可供性视域下博物馆非遗虚拟仿真系统设计方法。方法 首先概述了博物馆场景下,非遗虚拟仿真系统的现状,并对可供性理论及其应用进行梳理和提炼,提出可供性应用于博物馆非遗虚拟仿真系统设计的意义;其次从可供性视角分析博物馆非遗虚拟仿真系统设计层面存在的问题,进一步提出将可供性引入非遗虚拟仿真系统设计的机会和意义;最后通过分析非遗虚拟仿真系统的可供性设计节点特性,并结合前期相关研究,构建基于可供性理论的博物馆非遗虚拟仿真系统设计方法,并以广彩瓷虚拟仿真系统为例进行设计实践与可行性验证。结论 研究结合可供性理论,提出可供性视角下博物馆非遗虚拟仿真系统设计可分为功能结构层、场景交互层、信息设计层与文化分为层,并分别提出显性知识数据库构建与隐性知识可视化教学、空间仿真、实体仿真与结构仿真、表征引导信息与情境反馈信息、视觉元素非遗化与听觉媒介沉浸化设计原则,形成面向博物馆非遗虚拟仿真系统的设计方法,为构建自然交互体验的非遗虚拟仿真系统设计提供参考。     

Management systems and program concepts for an integrated CAD process

A new model for the process of machine design is proposed. The model consists of the following three components: PDM, product-defining models; PDD, product-defining data; and OP, operational principles. Using these main components, the complete design process can be presented in an operation structure (OS). Any system for integrated and flexible CAD that is based on this model must support all steps of the design process.     

A method of rapid identification of heat fluxes

In design, development, and operation of crucial engineering systemssubjected to high heat fluxes, it is often necessary to observe the thermal state of the object in real time. The authors suggest an approach that is based on the methodology of solution of inverse heat-conduction problems (IHCP) and is a special adaptation of these methods for solution of observation problems. The approach is based on the idea of the possibility of identifying the current thermal state of the object with the use of measurements that are chronologically close to the current time, which leads to formulation of the retrospective boundary-value IHCP in a local time interval. A solution to this problem is considered, and results and estimates of the accuracy of simulation are presented. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 1, pp. 30–40, January–February, 1998.     

Hamilton's law of variable mass system and time finite element formulations for time‐varying structures based on the law

Traditional principles of mechanics are primarily conceived for constant mass systems, which are only valid if mass is gained or lost at null velocity with respect to an inertial reference frame for variable mass systems, thus the numerical algorithms for time‐varying structures based on these principles are only suitable for this special case. In this paper, Hamilton's law of variable mass system is derived based on Meshchersky's fundamental equation, and two classes of novel time finite element formulations for linear systems with arbitrary continuous time‐varying parameters are developed based on the previous law. The formulations are verified extensively through numerical examples in which the convergence and effectiveness of algorithms are evaluated. Numerical examples demonstrate that compared with the algorithms for time‐varying structures that developed based on traditional principles of mechanics, the proposed algorithms provide extended capabilities in both time‐varying mass problems that mass is gained or lost at any velocity (such as rocket problem) and moving‐mass problems (such as vehicle‐bridge interaction problem) besides the time‐varying stiffness and damping problems, the proposed algorithms have a wider range of application. In particular, Hamilton's law of variable mass system provides a solid theoretical foundation for further research on the algorithm design for time‐varying structures. Copyright © 2014 John Wiley & Sons, Ltd.     

脉冲调宽乘法器在交流应用下的误差及标准功率、电压、电流测量仪的研制

本文讨论了脉冲调宽乘法器用于交流测量时交直流变换误差与时分割频率的关系，提出了一种新的准确计算方法，并对相移误差等因素作了分析，给出了减小误差的措施。最后介绍了基于上述分析而设计研制的标准功率、电压、电流测量仪，其测量功率、电压、电流的误差均小于００１％     

Variational multiscale enrichment for modeling coupled mechano‐diffusion problems

In this paper, a new multiscale–multiphysics computational methodology is devised for the analysis of coupled diffusion–deformation problems. The proposed methodology is based on the variational multiscale principles. The basic premise of the approach is accurate fine‐scale representation at a small subdomain where it is known a priori that important physical phenomena are likely to occur. The response within the remainder of the problem domain is idealized on the basis of coarse‐scale representation. We apply this idea to evaluate a coupled mechano‐diffusion problem that idealizes the response of titanium structures subjected to a thermo–chemo–mechanical environment. The proposed methodology is used to devise a multiscale model in which the transport of oxygen into titanium is modeled as a diffusion process, whereas the mechanical response is idealized using concentration‐dependent elasticity equations. A coupled solution strategy based on operator split is formulated to evaluate the coupled multiphysics and multiscale problem. Numerical experiments are conducted to assess the accuracy and computational performance of the proposed methodology. Numerical simulations indicate that the variational multiscale enrichment has reasonable accuracy and is computationally efficient in modeling the coupled mechano‐diffusion response. Copyright © 2011 John Wiley & Sons, Ltd.     

Process-oriented tolerancing for multi-station assembly systems

In multi-station manufacturing systems, the quality of final products is significantly affected by both product design as well as process variables. Historically, however, tolerance research has primarily focused on allocating tolerances based on the product design characteristics of each component. Currently, there are no analytical approaches to optimally allocate tolerances to integrate product and process variables in multi-station manufacturing processes at minimum costs. The concept of process-oriented tolerancing expands the current tolerancing practices, which bound errors related to product variables, to explicitly include process variables. The resulting methodology extends the concept of “part interchangeability” into “process interchangeability,” which is critical due to increasing requirements related to the selection of suppliers and benchmarking. The proposed methodology is based on the development and integration of three models: (i) the tolerance-variation relation; (ii) variation propagation; and (iii) process degradation. The tolerance-variation model is based on a pin-hole fixture mechanism in multi-station assembly processes. The variation propagation model utilizes a state space representation but uses a station index instead of a time index. Dynamic process effects such as tool wear are also incorporated into the framework of process-oriented tolerancing, which provides the capability to design tolerances for the whole life-cycle of a production system. The tolerances of process variables are optimally allocated through solving a nonlinear constrained optimization problem. An industry case study is used to illustrate the proposed approach.     

Multiscale coupling using a finite element framework at finite temperature

This paper presents the formulation and application of a multiscale methodology that couples three domains using a finite element framework. The proposed method efficiently models atomistic systems by decomposing the system into continuum, bridging, and atomistic domains. The atomistic and bridging domains are solved using a combined finite element–molecular mechanics simulation where the system is discretized into atom/nodal centric elements based on the atomic scale finite element method. Coupling between the atomistic domain and continuum domain is performed through the bridging cells, which contain locally formulated atoms whose displacements are mapped to the nodes of the bridging cell elements. The method implements a temperature‐dependent potential for finite temperature simulations. Validation and demonstration of the methodology are provided through three case studies: displacement in a one‐dimensional chain, stress around nanoscale voids, and fracture. From these studies differences between multiscale and fully atomistic simulations were very small with the simulation time of the proposed methodology being approximately a tenth of the time of the fully atomistic model. Copyright © 2012 John Wiley & Sons, Ltd.     

Cryogenic transistor measurement and modeling for engineering applications

This article deals with the methodology of an electronic system design at liquid-helium temperatures. This technique includes the active device selection, characterization and simulation. Based on certain engineering criteria one commercial reference of SiGe heterojunction bipolar transistors is selected. Then, the technique of device characterization and measurement is considered. Typical output characteristics are given for this reference. All the tested devices of this reference are classified into three groups according to the presence of different low-temperature phenomena. An accurate and easy-to-use neural network model based on their experimental DC characteristics is proposed. This model is implemented in Agilent ADS Software, and the simulation results are compared with measurements in the course of the cryogenic amplifier design.     

USB多路数据采集器

针对目前大多数采集系统无法实现多通道高分辨率采样及携带不方便等情况,提出了一种基于USB的多路数据采集系统的设计方法。系统利用ARM+FPGA+AD7656的系统组合实现16路通道同步信号采样,FPGA用于实现对A/D转换的逻辑控制,通过ARM7处理器对A/D转换数据进行处理,再由USB接口与计算机进行数据通信。测试结果表明,基于FPGA与ARM的多通道数据采集系统结构简单、控制方便、设计成本较低,能够准确快速地对16路信号同时进行采集。     

An option generation and selection methodology for process equipment selection

The option generation and selection (OGS) methodology forms part of a general approach for the design of agile chemical plants based on business, product and process knowledge, with support from information models. This paper describes an equipment OGS tool that encompasses the principles of combinatorial process and plant design. The main components of the methodology are: an equipment option generation model described as a set of objects, and the net relationships between them, and an equipment option selection model which consists of procedures for equipment selection. The two models are supported by databases containing information specific to each equipment type, the concept on which the equipment is based, and relationships with other equipment types. Robust, systematic and complete forms of these models can be used as the basis of an expert system for process equipment design, with equipment selected using these tools satisfying the requirements of both specific processes and families of processes (that contain common features, similar functional groups or similar raw material requirements for process operations). Application of the methodology also allows the evaluation of options for reconfiguring existing plant.     

Towards automating the discovery of certain innovative design principles through a clustering-based optimization technique

In this article, a methodology is proposed for automatically extracting innovative design principles which make a system or process (subject to conflicting objectives) optimal using its Pareto-optimal dataset. Such ‘higher knowledge’ would not only help designers to execute the system better, but also enable them to predict how changes in one variable would affect other variables if the system has to retain its optimal behaviour. This in turn would help solve other similar systems with different parameter settings easily without the need to perform a fresh optimization task. The proposed methodology uses a clustering-based optimization technique and is capable of discovering hidden functional relationships between the variables, objective and constraint functions and any other function that the designer wishes to include as a ‘basis function’. A number of engineering design problems are considered for which the mathematical structure of these explicit relationships exists and has been revealed by a previous study. A comparison with the multivariate adaptive regression splines (MARS) approach reveals the practicality of the proposed approach due to its ability to find meaningful design principles. The success of this procedure for automated innovization is highly encouraging and indicates its suitability for further development in tackling more complex design scenarios.     

中国主流家庭生活形态下的卫浴设计研究

目的 通过对中国主流家庭生活形态的认识,深入分析三代人的生理需求、心理需求以及体验需求,探索卫浴产品更加贴近使用者的设计形式。方法 针对目前卫浴市场的繁荣景象,就其不同的用户身心特点及需求进行深挖与总结,是促进卫浴设计创新的有效尝试。本文立足于这一论点,分别从卫浴产品在安全性、独立性、简易性等层面的表现总结基本的设计原则,提出基于几项原则的改进设计,在中国主流家庭生活形态下从最主要的儿童、老人和户主夫妻三方面的现实需求展开各种关联性探索,探讨当前卫浴产品设计的缺失,总结科学化的设计思路与基本方法,尝试完成系统化的设计方案。结论 卫浴产品与当前我国主流家庭生活形态的契合式发展,无疑是卫浴产品获得更大发展价值的有益探索,是使用者获得身心愉悦的良好支撑,有利于在未来为人们提供更加舒适的体验,使多层次需求得到极大满足。     

Generalized methodology for modeling and simulating optical interconnection networks using diffraction analysis

Research in the field of free-space optical interconnection networks has reached a point where simulators and other design tools are desirable for reducing development costs and for improving design time. Previously proposed methodologies have only been applicable to simple systems. Our goal was to develop a simulation methodology capable of evaluating the performance characteristics for a variety of different free-space networks under a range of different configurations and operating states. The proposed methodology operates by first establishing the optical signal powers at various locations in the network. These powers are developed through the simulation by diffraction analysis of the light propagation through the network. After this evaluation, characteristics such as bit-error rate, signal-to-noise ratio, and system bandwidth are calculated. Further, the simultaneous evaluation of this process for a set of component misalignments provides a measure of the alignment tolerance of a design. We discuss this simulation process in detail as well as provide models for different optical interconnection network components.     

A fuzzy QFD program modelling approach using the method of imprecision

The use of quality function deployment (QFD) to aid decision making in product planning has gained extensive international attention, but current QFD approaches are unable to cope with complex product planning (CPP) characterized by involving multiple engineering characteristics (ECs) associated with significant uncertainty. To tackle this difficulty, in this paper, fuzzy set theory is embedded into a QFD framework and a novel fuzzy QFD program modelling approach to CPP is proposed to optimize the values of ECs by taking the design uncertainty and financial considerations into account. In the proposed methodology, fuzzy set theory is used to account for design uncertainty, and the method of imprecision (MoI) is employed to perform multiple-attribute synthesis to generate a family of synthesis strategies by varying the value of s, which indicates the different compensation levels among ECs. The proposed methodology will allow QFD practitioners to control the distribution of their development budget by presetting the value of s to determine the compensation levels among ECs. An illustrative example of the quality improvement of the design of a motor car is provided to demonstrate the application and performance of the modelling approach.     

Optimized Eddy Current Detection of Small Cracks in Steam Generator Tubing

A complete, computer based design methodology is described, aiming to develop an eddy current sensor with increased sensitivity to flaws, and reduced sensitivity to probe lift-off. The first part of the paper contains an analysis performed in order to establish detailed criteria for an effective design. Numerical investigations have been carried out and their results are discussed, regarding various problems of detectability and lift-off noise level. Based on these results, in the second part two probe arrangements are proposed, and it is shown how their performance parameters could be further improved.