A practical control system for optimizing production schedules

This paper describes a, general model for planning work flow through a multiprocess production system and proposes a new practical scheme of control for scheduling. The features of the model are based on experience of a wide variety of industries and a means is considered for resolving the conflicts between different objectives such as meeting due dates and reducing work in progress. The control system presumes that only the inlet times of the jobs into the production system can actually be decided and managed by a production planner, and not the subsequent internal operation start times, as previous studies have often assumed. A method for optimizing the schedule is developed on the basis of this form of control and it is illustrated on a small example. Finally implementation factors and extensions are discussed.     

Estimations of production yields for selection of a practical optimal optical coating design

Modern design approaches enable one to construct a series of theoretical designs with excellent spectral properties for almost all optical coating design problems. Selection of a practical optimal design among a variety of possible theoretical designs becomes a key issue. We demonstrate how preproduction estimations of expected production yields can be used for selection of a practical optimal design. The question of reliability of such estimations is also addressed.     

A practical fab design procedure for wafer fabrication plants

Facility design is crucial to the performance of wafer fabs in the semiconductor industry. This research proposes a practical Fab Design Procedure (FDP) to conduct quick calculations to develop and evaluate initial fab design alternatives. A series of practical formulae are presented to sequentially determine the following design parameters from an interbay point of view: the required number of machines; machine grouping and allocation; interbay flow matrix; bay dimension and location; interbay distance matrix; the required number of vehicles in an interbay material handling system; and the average wafer moving distance. Rules-of-thumb for wafer fab design on the basis of FDP are also suggested. A case study is used to demonstrate the effectiveness and efficiency of FDP. Results indicate that FDP is able to quickly calculate the required number of machines and related fab design parameters. With this tool, fab designers would be able to evaluate design alternatives and conduct what-if analysis in the initial phase of fab design.     

A primal decomposition method for the integrated design of multi-period production–distribution systems

We study the integrated design of strategic supply chain networks and the determination of tactical production-distribution allocations in the case of customer demands with seasonal variations. Given a set of potential suppliers, potential manufacturing facilities and distribution centers with multiple possible configurations, and customers with seasonal demands, the goal is to determine the configuration of the production-distribution system with the lowest sum of supply, production, transportation, inventory, and facility costs such that seasonal customer demands are met. We develop a mixed integer programming formulation and an integrated design methodology based on primal (Benders) decomposition. For a case study in the packaging industry, specialized acceleration techniques reduced the running times by a factor of 480. The company projects savings of 2% or $8.3 million by using the integrated rather than the optimal hierarchical configuration.     

A practical method for uniaxial tension test of concrete

A test method for uniaxial tension test of concrete to obtain tension softening curves has not been established yet, because there are several difficulties in performing the test. In the past 40 years, many different test conditions, sometimes even completely opposite conditions have been adopted. In order to show which conditions should be selected and why the conditions should be selected, theoretical and experimental investigation was carried out. For the experiment, prismatic specimens with notches and an originally designed gear system preventing secondary flexure were adopted. It was shown that the tension softening curves were successfully monitored by the present procedure with a high success ratio. A practical test procedure of uniaxial tension test of concrete was proposed based on the investigation.     

实用干涉合成孔径声纳复图像配准法

海底地貌测绘的最新技术是利用干涉合成孔径声纳(InSAS)进行三维立体成像,其信号处理的关键在于成像之后的图像配准、干涉成像等步骤。图像配准的精度直接影响相位图的质量,从而影响所求目标区域高度的准确性。在分析InSAS复图像数据特点的基础上给出一种实用的基于最大干涉频谱法的复图像配准方法,缩减了配准搜索范围,在一定程度上提高了配准速度和精度。利用该方法对湖试测得的湖底地貌数据进行配准,用复图像相干系数和干涉相位图的残余点数对配准效果进行评估,通过配准前后的参数比较,证实了最大干涉频谱法用于InSAS复图像配准能够取得较好的配准效果。     

A practical design of a cylindrical tissue-equivalent proportional counter for microdosimetry

A 12 mm tissue-equivalent proportional counter (TEPC) was designed, constructed and successfully tested. This detector achieves features common to others TEPCs, but it does not use field shaping electrodes and it is able to work at higher bias voltages which makes it capable of measuring the whole range of energy deposition events for gamma rays. The following approach was used to design the detector: first of all the use of a cylindrical shape detector featured as simple as possible but keeping its performance as well, the next point is to avoid the use of field shaping tubes and the last one is to make the preamplifier small and as close as possible to the detector. Its construction is based on a cylindrical proportional counter with A-150 tissue-equivalent material as cathode, TE-methane gas as a proportional gas and a 20 microns diameter wire as anode.     

A practical method for accurate quantification of large fault trees

This paper describes a practical method to accurately quantify top event probability and importance measures from incomplete minimal cut sets (MCS) of a large fault tree. The MCS-based fault tree method is extensively used in probabilistic safety assessments. Several sources of uncertainties exist in MCS-based fault tree analysis. The paper is focused on quantification of the following two sources of uncertainties: (1) the truncation neglecting low-probability cut sets and (2) the approximation in quantifying MCSs. The method proposed in this paper is based on a Monte Carlo simulation technique to estimate probability of the discarded MCSs and the sum of disjoint products (SDP) approach complemented by the correction factor approach (CFA). The method provides capability to accurately quantify the two uncertainties and estimate the top event probability and importance measures of large coherent fault trees. The proposed fault tree quantification method has been implemented in the CUTREE code package and is tested on the two example fault trees.     

Optical design of hybrid-type attenuated phase-shift masks for extreme-ultraviolet lithography by use of a Fabry-Perot interference filter

We have designed what we believe to be new hybrid-type attenuated phase-shift masks for extreme-ultraviolet optical lithography by use of a Fabry-Perot interference filter. The designs for the attenuated phase-shift masks show a smaller step height for less geometric shadow effects than additive- and subtractive-type attenuated phase-shift masks, a contrast higher than 94% for both deep-ultraviolet and extreme-ultraviolet wavelength regimes, and a 180 degrees phase-shift in the extreme-ultraviolet wavelength regime.     

An applied model for the facilities design problem

A model ia described which can be used to assist in the design of a facility, where the facilities design includes the selection of the materials handling system and the placement of departments within the facility. The model is entitled COFAD, an acronym representing Computerized FAcilities Design. COFAD selects the facilities design which approaches the minimal materials handling system cost. The input requirements and the utilization of COFAD are demonstrated via an example problem. Although it is shown that the model results in good solutions, due to the complexity of the design problem, no claim of optimality can be made.     

Analytic design of monitoring facilities for integrated circuit inspection

A method is proposed for the analytic design of monitoring facilities that enables one to choose the characteristics on the basis of user optimality: maximum performance in using the facilities. That method does not require any additional data over and above those that a designer normally disposes of. Translated from Izmeritel’naya Tekhnika, No. 1, pp. 12–14, January, 2009.     

The production switching heuristic: A practical revision

Production Switching Heuristics (PSH) have been suggested as realistic, practical alternatives to more sophisticated aggregate planning and scheduling models. A modified, two-level heuristic is presented and its properties investigated by use of the classical paint factory data (Linear Decision Rule). Even under relatively extreme circumstances, its cost performance is promising when compared with the LDR, LP and the original PSH.     

Computer-based FMS facilities design tool

FMS layout design is a complex process, involving a large number of alternatives, which contributes generously to the usual two-year FMS planning lead time. The need for a comprehensive, yet easy-to-use methodology or tool which can reduce this large number of alternatives to a more reasonable figure has motivated this research. A survey of existing FMSs was undertaken with the intention of identifying some of the more common (dominant) types of layouts, and to develop, if possible, a methodology for the selection of such layouts. However, almost every FMS was found to have a unique layout. For a given FMS under consideration, the capabilities with respect to the parts which can be manufactured is essentially given. The determining features of the resultant design of the FMS, therefore, are primarily based upon the design of the material handling system which integrates the FMS. However, as the number of machines in a FMS increase, the number of part sequences and alternate configurations increase at a dramatic rate. To assist in the preliminary design process, an interactive computer-based program has been developed to aid the search for non-inferior layouts to suit the exact part sequence needs of each FMS. Six criteria-three related to the distances parts travel during manufacturing and three related to the capital costs of the FMS-are provided to assist the user in selecting an appropriate arrangement. The program is described and its use is demonstrated in developing improved arrangements over an example FMS which was published in the literature. Although the reader is cautioned that the results were developed using only static measures, the results do indicate that significantly improved designs are possible using the proposed methodology     

A practical engineering method for fuzzy reliability analysis of mechanical structures

The fuzzy sets theory in reliability analyses is studied. The structure stress is related to several other variables, such as structure sizes, material properties, external loads; in most cases, it is difficult to be expressed in a mathematical formula, and the related variables are not random variables, but fuzzy variables or other uncertain variables which have not only randomness but also fuzziness. In this paper, a novel approach is presented to use the finite element analysis as a “numerical experiment” tool, and to find directly, by fuzzy linear regression method, the statistical property of the structure stress. Based on the fuzzy stress–random strength interference model proposed in this paper, the fuzzy reliability of the mechanical structure can be evaluated. The compressor blade of a given turbocharger is then introduced as a realistic example to illustrate the approach.     

A practical method for singular integral equations of the second kind

A convenient and efficient numerical method is presented for the treatment of Cauchy type singular integral equations of the second kind. The solution is achieved by splitting the Cauchy singular term into two parts, allowing one of the parts to be determined in a closed-form while the other part is evaluated by standard Gauss-Jacobi mechanical quadrature. Since the Cauchy singularity is removed after this manipulation, the quadrature abscissas and weights may be readily available and the placement of the collocation points is flexible in the present method. The method is exact when the unknown function can be expressed as the product of a fundamental function and a polynomial of degree less than the number of the integration points. The proposed algorithm can also be extended to the case where the singularities are complex and is found equally effective. The proposed algorithm is easy to implement and provides a shortcut for programming the numerical solution to the singular integral equation of the second kind.     

Client-server model of integrated production facilities

The objective of the reported research is to develop a new design-model of distributed facilities, where production is integrated and operates under computer supported collaboration. The main innovation has been the exploitation of the analogy of the highly effective client-server computing environment for the benefit of production facilities design. As a variant of flexible manufacturing systems, the challenge is to manage the distributed material and information flow. The solution approach developed here is by protocols. The goal is to explain the design of the client-server production model and its coordination protocols, including functions of synchronization and resource allocation. An implementation of the model in an assembly and test facility and its application over the last three years serve to explain the model and illustrate its significance. Time-out and priority assignment protocols are defined and analysed in the context of the model to demonstrate its specific benefits.     

A better method for verifying production reliability

Various schemes have been created for verifying that reliability is not degraded during production. These include the periodic performance of reliability tests during production, three versions of an all-equipment reliability test plan and Bayesian approaches. Each method has its drawbacks. The purpose of all of these is to verify that the production process is continuing to produce products of acceptable reliability, for which the long-existing tools of statistical process control are directly applicable and advantageous. A method of verifying production reliability based on the use of a control chart for failure rate is proposed as a better way than the current standards and alternatives discussed in this paper.     

A simple method for SC-cut resonator design

Presents a design method utilizing simple semi-empirical equations for round, plano-convex SC-cut resonators. These equations were developed on the basis of experimental results, collected over a long period, relating SC-cut resonator design and performance covering a wide range of frequencies, radii of curvature, and plate diameters. The equations make possible the design of fundamental, third overtone, and fifth overtone resonators. An example calculation of resonator parameters and comparison with experimental results are also presented     

A note on 'Maximally weighted graph theoretic facilities design planning'

This note explores the significance of John and Hammond contributions in solving the facilities design problem using graph theory concepts. The note suggests arranging vertices of the constructed graph in a one-dimensional array referred to as a spinal graph to reduce the sensitivity of graph theoretic procedures to the vertex's replacement.