The design and validation of a digital simulation model for job shop control decision making

A previous paper (Browne et al. 1981) identified the decision making problems associated with job shop control and presented an objective function for measuring its performance. Given that definition of job shop control and cost-based objective function, simulation modelling offers the best prospect of a solution of the problem of providing a management tool to aid in the decision making associated with job shop control. This paper provides a detailed analysis of the design of such a model. The model, written in the GASP fV simulation language and running on a CDC 7600 computer, is based on the job shop of a major machine tool manufacturer and has been validated against actual job shop performance.     

Experiments with stock control policies and leadtime setting rules,using an aggregate planning evaluation model of a make-for-stock shop

A simulation model, driven by real order time series, of an actual make-for-stock shop is described. A broad spectrum of different sets of decision rules has been incorporated in the model in an attempt to represent as many as possible of the production controls which might be utilized by a production manager. Experiments designed to determine the impact on a production cost function of changes in decision rules can be conducted over a wide range of conditions, with the objective of assessing the robustness of rule changes.

To illustrate the use of the model, the results of experiments in two areas of production control are presented. Changing the stock control policy used by the host company to a re-order level policy type was shown to lead to significant improvements in performance across the range of conditions examined, in the case of a low marginal cost of stock review. In experiments with leadtime setting rules, improvements in performance were obtained across the spectrum of experimental conditions when the leadtime distribution was altered to one based on batch work content and number of operations and the tightness of the mean leadtime was simultaneously increased.     

The setting up of a search system for patents at the Polytechnische Patentbibliothek of the Technische Hochschule,Ilmenau (Ilmenau Technical University)

The decentralized polytechnical patent library of the Technische Hochschule Ilmenau (GDR) is from the point of view of its structure and the nature of its services characterized by: a stock of documents limited in volume and optimized as far as contents and access are concerned and a computerized search system through which state-of-the-art searches and preliminary novelty and infringement searches can be carried out rapidly and in a cost-efficient way.The criteria for selecting the documents stocked, the approach to computerized analysis of documents and the search strategy are explained in detail. At present the system is being tested in the area of information technology.     

NEWFIT,a computer program for the analysis of alpha,X-ray and gamma-ray spectra

The computer program NEWFIT has been developed for analysis of gamma-ray, X-ray and alpha spectra. The general shape used for the analysis of activity peaks is a Gaussian function. An exponential tail can be added for use in alpha spectra analysis. The algorithms to analyze the peak shapes and the program operation are presented. Special features include the ability to create realistic peak shapes based on the systematic deviations of the real peaks from the theoretical Gaussian shape, as well as the option to constrain the calculated areas of peaks from a given alpha emitting nuclide to their relative branching ratios. The program is available from the authors.     

面向事务处理的容错计算机系统结构设计与实现

提出了一种面向事务处理的容错计算机体系结构,设计了基于三模冗余的仲裁器和仲裁算法。在集群中,利用中心结点故障检测机制,采用仲裁器得到了一个逻辑上高可靠的管理态结点,通过该结点可以实现系统快速故障诊断和故障恢复。实验结果表明：节点间故障检测时间小于2s,故障节点切换时间小于5s,该系统的故障检测、故障节点切换可以满足事务处理系统对可靠性的要求。     

A comparison of ideal and real moist air models for calculating humidity ratio and relative humidity in the 213.15 to 473.15 K range and up to a pressure of 1 MPa

This study evaluates how the ideal mixture model of moist air approximates a real mixture model when determining both humidity ratio and relative humidity for the 0.1- to 1-MPa pressure range and the -60 to 200°C temperature range. The relevant thermodynamic properties are calculated using, among others, a specific algorithm based on the relationships proposed by Hyland and Wexler corrected for the new ITS-90 temperature scale.     

The electrical conductivities of steel and other candidatematerials for shrouds in a beam-waveguide antenna system

This article presents the results of electrical conductivity measurements made at 8.420 GHz on samples of the structural steel material used to fabricate shrouds on a Deep Space Network (DSN) 34-m-diameter beam-waveguide (BWG) antenna. Test results show that the structural steel samples at this microwave frequency had effective conductivities that were about 50 times worse than published dc values and also 230 times worse than the measured conductivities of aluminum test samples. Conductivity data are also presented for other candidate materials that could be used to fabricate BWG shrouds. Of interest are the improvements or degradations that were observed after some of the metal test samples were surface treated, plated, or painted     

The performance of a microchannel plate at cryogenic temperatures and in high magnetic fields, and the detection efficiency for low energy positive hydrogen ions

We have conducted a systematic study of the performance of a microchannel plate at cryogenic temperatures, and in a magnetic field perpendicular to the plate surface of up to 2.5 T. We observe no change in the characteristic pulse height distribution down to temperatures near 4 K if the count rate is kept sufficiently low. With increasing count rates the onset of saturation effects can be observed to be temperature dependent. For the specific plate used, this occurs around 1 kHz at the lowest temperature. This behavior is in good agreement with calculations based on a widely used model for the gain function of microchannel plates, if the plate resistance is allowed to be temperature dependent. Additionally we have studied the detection efficiency for low energy hydrogen ions of a chevron type microchannel plate under a variety of operating conditions at room temperature, and find the detection efficiency to level off around 60% at energies above 1 keV, if the plate is operated in a saturated gain mode.     

The prevalence and reliability of visibility aid and other risk factor data for uninjured cyclists and pedestrians in Edmonton, Alberta, Canada

This study was conducted to determine the prevalence and reliability of risk factors collected on uninjured cyclists-pedestrians in Edmonton, Alberta, and what characteristics predict cyclist-pedestrian visibility. At randomly selected locations from July 2004 to August 2004, two independent observers recorded cyclist-pedestrian characteristics such as age, sex, clothing color, use of reflectors, flags, helmets, and a subjective impression of visibility. Data were collected on 836 individuals; most were either walking/jogging (approximately 63%) or cycling (approximately 33%). For non-cyclists, the prevalence of bright colored clothing on the trunk ranged from 12.7 to 14.7%. Few people used any kind of reflective strips. Inter-observer agreement (Kappa) ranged from 0.37 (visibility assessment) to 0.99 (sex). For cyclists, 17-19% of headgear was brightly colored, and 13-14% was white. Approximately one-fourth had a front light; half had a rear reflector. Few cyclists used a flag and just over half used spoke reflectors. Kappa ranged from 0.35 (observer assessed speed) to 0.95 (head gear and sex). A major trunk color of orange, red, yellow or white resulted in a higher visibility rating for both cyclists and pedestrians. The results indicate a low prevalence of visibility aid use among cyclists and pedestrians, but there appears to be acceptable inter-observer reliability for most data collected. Further work is required before an overall visibility rating can be used in place of component scores.     

Characterization and simulation of an open piston compressor for application on automotive air-conditioning systems operating with R134a,R1234yf and R290

A semi-empirical characterization and simulation model for automotive air-conditioning open piston compressor is developed. The model is based on fundamental conservation principles and takes into account pressure drop and heat transfer in suction and discharge passages. Fundamental conservation principles equations, as well as volumetric and isentropic efficiencies, pressure drop, heat transfer and property equations are combined to form a system of non-linear algebraic equations. They are worked out so as to identify constants that are sole characteristics of the compressor and should not vary with different operating conditions or refrigerants. A numerical method determines such constants from existing experimental data, thus characterizing the compressor. Experimental data were obtained from tests carried out by Navarro et al. (2013) for an open piston compressor running with fluids R134a, R1234yf and R290. First, the experimental data were employed to determine the characterization parameters of the compressor. Then, the simulation model, with the R134a-based parameters, was applied to simulate the compressor operation with R1234yf and R290. Good agreement was obtained between predicted and experimental values, proving the suitability of the model for the study of new refrigerants.     

Procedure and test unit for studying the operating capacity of gas turbine engine blades under the combined action of mechanical and thermal loads,and atmosphere in a gas-dynamic test bed

A procedure and a gas-dynamic test bed are described for testing gas turbine engine blades with programmed mechanical and thermal loading. The test bed provides fatigue and heat resistance tests for GTE blades under conditions of the corrosive action of a high-temperature gas stream including variable thermodynamic parameters as well as other corrosive components, for example sea water salts injected into the stream in order to simulate GTE marine operating conditions.Deceased.Translated from Problemy Prochnosti, No. 6, pp. 71–77, June, 1993.     

The effect of frequent hemodialysis on matrix metalloproteinases,their tissue inhibitors,and FGF23: Implications for blood pressure and left ventricular mass modification in the Frequent Hemodialysis Network trials

Background: Frequent hemodialysis modifies serum phosphorus, blood pressure, and left ventricular mass (LVM). We ascertained whether frequent hemodialysis is associated with specific changes in biomarker profile among patients enrolled in the frequent hemodialysis network (FHN) trials. Methods: This was a post hoc analysis of biomarkers among patients enrolled to the FHN trials. In particular, we hypothesized that frequent hemodialysis is associated with changes in a specific set of biomarkers which are linked with changes in blood pressure or LVM. Results: Among 332 randomized patients, 243 had biomarker data available. Of these, 124 patients were assigned to 3‐times‐a‐week hemodialysis (94 [Daily Trial] and 30 [Nocturnal Trial]) and 119 patients were assigned to 6‐times‐a‐week hemodialysis (87 [Daily Trial] and 32 [Nocturnal Trial]). Frequent hemodialysis lowered phosphate, blood pressures, LVM, log fibroblast growth factor (FGF)23, and tissue inhibitors of metalloproteinase (TIMP)—2 levels. The fall in phosphate was associated with changes in FGF23 (r = 0.48, P < 0.001) [Daily Trial] and (r = 0.55, P < 0.001) [Nocturnal Trial]) and tended to be associated with changes in systolic blood pressure (r = 0.18, P = 0.057) [Daily Trial] and (r = 0.31, P = 0.04) [Nocturnal Trial]. Within the Daily Trial, changes in MMP2 (r = 0.20, P = 0.034) were associated with changes in LVM. In the Nocturnal Trial, changes in TIMP‐1 (r = 0.37, P = 0.029) and MMP 9 (r = ?0.38, P = 0.01) were associated with LVM changes. MMP2 changes were associated with changes in systolic blood pressure. Conclusions: Reduction of serum phosphate by frequent hemodialysis may modulate FGF23 levels and systolic blood pressure. Markers of matrix turnover are associated with LVM changes. Frequent hemodialysis may affect pathological mediators of chronic kidney disease‐mineral bone‐metabolism disorder.     

Accident versus near miss causation: a critical review of the literature, an empirical test in the UK railway domain, and their implications for other sectors

An essential assumption for the usefulness of basing accident prevention measures on minor incidents is the common cause hypothesis: that causal pathways of near misses are similar to those of actual accidents (such as injuries and damages). The idea of a common cause hypothesis was originally proposed by Heinrich in his seminal book "Industrial Accident Prevention" [McGraw-Hill, New York]. In this paper, it is argued that the hypothesis of similarity of causes for major and minor accidents has become confounded with the interdependence of the ratio relationship between severity and frequency. This confounded view of the hypothesis has led to invalid tests of the hypothesis and erroneous conclusions. The evidence from various studies is examined and it is concluded that the hypothesis has not been properly understood or tested. Consequently, such a proper test was carried out using data from the UK railways which were analysed using the confidential incident reporting and analysis system (CIRAS) 21 cause taxonomy. The results provide qualified support for the common cause hypothesis with only three out of the 21 types of causes having significantly different proportions for the three consequence levels investigated: 'injury & fatality', 'damage' and 'near miss'.     

The use of X-ray diffraction, microscopy, and magnetic measurements for analysing microstructural features of a duplex stainless steel

X-ray diffraction, light optical microscopy, and magnetization saturation measurements were employed to analyse the microstructural features of a UNS S31803 duplex stainless steel modified by high-temperature treatments. The samples were heated to 1300 °C and cooled by different ways to produce five different microstructures. Solution treatments at 1000 °C were also employed to produce another five conditions. Three methods were employed to determine the austenite/ferrite proportions. X-ray diffraction gave higher austenite values than the other methods, due to the influence of texture, but can be successfully used to determine the microstrain level in each phase. Magnetic saturation measurement is a very simple and precise method for quantification of austenite and ferrite volume fractions in samples that were fast-cooled and slow-cooled. Light microscopy can give a fast and precise measurement of the phase proportions and reveals important features related to the morphology of the phases, but in the samples where the austenite content is low, quantification becomes difficult and imprecise.     

The attachment, modification and release of gold nanoparticles from a photolabile solid phase synthesis resin, a new methodology for nanoparticle surface modification

Gold nanoparticles were synthesis by a two-phase method (water/toluene) and attached to a solid phase synthesis (SPS) resins. The average diameter of the nanoparticles determined by TEM image analysis was 3.9 ± 0.3 nm. The SPS resin used was an o-nitrobenzyl based photolabile system. This was first loaded with Fmoc-Cys(Trt)-OH following standard PyBOP protocols. UV-Vis spectroscopy was used to monitor the reaction of the nanoparticle solution with the SPS resin. The bound nanoparticles were released from the SPS resin by exposure to UV light, (λ = 350 nm, intensity = 10 000 μW cm^− 2) and shown to reform a stable solution. The nanoparticles were further modified into clusters on the surface of the SPS resin by the addition of pentanedithiol or assembled into nanoparticle dimers by the addition of a 1,3-propanediamine post photolytic release.     

The resistivity, temperature coefficient of resistivity and thermoelectric power of thin continuous metal films II: A methodology for computer processing of thin film data to extract parameters with associated error estimates

A straightforward computer-based general methodology is presented which will enable parameter values and associated error estimates to be extracted from experimental thin film data points. The methodology operates on exact thin film relationships and overcomes problems in interpreting results, such as having to resort to the use of approximate thin film relationships.

The methodology is presented within the framework of the well-known Fuchs-Sondheimer model for conduction in thin continuous metal films. However, its general nature means that it is equally applicable to other theoretical thin film models. An illustration of the methodology's use is given by applying it to a set of thin film resistive, temperature coefficient of resistivity and thermoelectric power data obtained from measurements on thin continuous copper films.     

The generation, use and disposal of waste crankcase oil in developing countries: a case for Kampala district, Uganda

Waste crankcase oil (WCO), the oil that is removed from motor engines during an oil change, is frequently discarded into the environment, resulting in pollution of both aquatic and terrestrial ecosystems. In some developing countries, this common hazardous material is not properly managed. In Uganda little is known about its generation, utilization, and disposal. These factors were investigated using in-depth interviews of a sample of mechanics from 379 motor repair garages and 109 fuel stations in the Kampala district. Most garages (94%) and fuel stations (96%) in the study area offered oil-changing services. On average, each garage produced 62 l, and each fuel station produced 134 l of WCO per week. In garages 35% was sold, 16% poured on the ground, 18% taken by vehicle owners and 31% given away for free. At fuel stations, 49% was picked by private collectors, 27% sold, 4% poured on the ground, 2% burnt, 13% taken by vehicle owners, and 6% given away for free. Uses of WCO included coating roofing timber and fencing posts, use in timber cutting, marking play grounds, and pest control in animals. Its disposal involved burning, and pouring in the environment. Lack of policy and information for proper handling of WCO contributed to the poor management of WCO exhibited.     

The Normal Probability Plot as a Tool for Understanding Data: A Shape Analysis from the Perspective of Skewness,Kurtosis, and Variability

Continuous quality improvement is an effort to improve the quality of products, processes, or services. A program intended to effectively implement such efforts begins with the collection and analysis of data. The primary purpose of the normal probability plot, which is one of the most frequently used graphical tools by quality practitioners and researchers, is for normality testing; however, the plot offers other valuable insights into data analysis that have rarely been addressed in the research community. This article provides an overview of distributional characteristics in the context of the four sample moments and investigates how variations in these moments affect the normal probability plot, focusing primarily on the presence of skewness and kurtosis and the effects of variability. This article then lays out a comprehensive analysis of how various statistical characteristics within a data set can influence the shape and corresponding properties of a normal probability plot, demonstrating how variations in the characteristics of the data can reveal or mask the degree of concavity, convexity, or the S shape in the plot, as well as the spread of the data about the mean and in the tails. This can provide engineers with a better understanding of the ways in which data “communicate” through the plot, thereby providing a better basis for initial assumptions, as well as facilitating more accurate model estimation and optimization results thereafter. Copyright © 2011 John Wiley & Sons, Ltd.