A queueing network based system to model capacity and cycle time for semiconductor fabrication

In today's competitive semiconductor business environment, wafer manufacturers are facing continuous pressure to accurately predict cycle time and tool utilization, gauge the impact of changes in capacity available, assess the impact of changes in product mix and quantity, and determine action plans to improve operational performance. Discrete event simulation (DES) is a widely used approach to perform such an analysis. However, DES has some inherent shortcomings for these planning tasks. Analytical models, like queueing networks, have much shorter response times and additional advantages compared to DES. But due to the complexity of semiconductor manufacturing systems (SMS) queueing models were not able to model all the peculiarities of those. This paper provides an overview of the main features of the IBM Enterprise Production planning and Optimization System (EPOS), a queueing network based system, which closes this gap. EPOS has been in use in the 300 mm fabrication of IBM in Fishkill for more than 2 years and has turned out to be an invaluable tool to analyze the trade-offs of cycle time and capacity within this complex environment.

We present an in-depth decompositionanalysis using physical indicators oftrends in Carbon dioxide (CO2) emissions in the cementindustry in Brazil, China, South Korea andthe United States. Physical indicatorsallow a detailed analysis of intra-sectoraltrends, in contrast to the often usedmonetary indicators. We assess thecontribution of different factors affectingCO2 emissions in the cement industry,including change in product mix, efficiencyof power generation, changes in fuel mixand changes in energy efficiency. Thedecomposition results show that in allexamined countries, increased productionwas the main contributor to the increase intotal CO2 emissions. Energy-efficiencyimprovement is the most important factorthat led to the reduction of emissionintensities for all countries except Korea.For Korea, structural change in the productmix is the most important factorcontributing to the emission intensityreduction.

Hybrid ant systems for the dynamic facility layout problem

It is now widely accepted that predictions of such key quantities as imports, final demands, gross domestic output and employment depend crucially on a knowledge of the technology of an economy, and in particular of the input coefficients of the technology matrix. However, many investigations have pointed out that these coefficients change over time owing to alterations in the product mix at a sectoral level, changes in production techniques, relative price changes and economies of scale. Some econometric analysts have concentrated on relative price effects (Theil and Tilanus, 1964), and very few studies have considered the impact of product mix changes or economies of scale. Any analysis of the intertemporal behaviour of input-output coefficients requires a great deal of data, both on a time-series basis and with a uniform classification scheme. Such data are obviously very scarce, and as a consequence the attention of forecasters has shifted towards the incorporation of specialist technical information into the estimation of future coefficients. In common with earlier studies, this paper concentrates on the R.A.S. method of forecasting and examines an updating of the 1959 absorption flow matrices of nine European countries to the 1965 level of technology. The updated matrices, along with various derived quantities, are compared with the corresponding figures based on the actual 1965 tables at a 19-sector level of disaggregation. The data are prepared in a standardized framework by the Economic Commission for Europe (ECE) (1971) for twelve European countries for the year around 1959 and by the ECE data tape (1977) for nine European countries. The purpose of the ECE research programme was to make structural comparisons between various European countries. Data are obviously reduced from national tables to standardized tables following a homogeneous 19-sector scheme.

Discrete-event simulation is a common tool for the analysis of semiconductor manufacturing systems. With the aid of a simulation model, and in conjunction with sensitivity analysis and metamodeling techniques, robust design can be performed to optimize a system. Robust design problems often include integer decision variables. This paper shows a graphical approach to robust design that is effective in the presence of discrete or qualitative variables. The graphical robust design methodology was applied to a backend semiconductor manufacturing process. Changes in specific resource capacities and product mix were examined to determine their effect on the level and variance of cycle time and work in process.

Long-term tool elimination planning for a wafer fab

During the 1950s and 1960s American higher education underwent a major change in size and structure, with a vast expansion in enrollments and increased emphasis on graduate training and research, relative to undergraduate teaching. This chapter explores the implications of this changing product mix for our understanding of costs, subsidies, financing methods, and decision-making structures in higher education. We ask the following questions: . . . 1. How did universities finance their production of graduate training and research (G and R), which usually do not bring in enough revenues to cover their costs? 2. What differences, if any, were there in the behavior of public and private universities regarding the shift toward G and R? 3. How did this change in product mix affect relative costs in universities versus two- and four-year colleges, which still specialize in undergraduate teaching? 4. What are the implications of this analysis for our understanding of the costs and benefits of education and for future public policy? For example, to what degree do state legislators and private donors control the product mix in higher education and who ultimately gains from the resources they provide?. . . Specifically, I characterize universities as multiproduct nonprofit organizations (NPOs) engaging in the teaching of undergraduates as a profitable activity, in order to subsidize graduate training and research, which are loss-making but yield direct utility to them. Cross-subsidization by NPOs, then, is an alternative to direct government funding of socially beneficial goods such as research, under certain circumstances. With certain differences that we shall note, this characterization applies to public and private institutions, and the term NPO is used for both in this chapter. At private universities, during the 1950s and 1960s, profits were generated mainly by huge tuition increases, made possible by rapidly rising demand, as we shall see below. State universities, too, engaged in cross-subsidization to finance G and R. However, since state universities often do not control or retain tuition revenue, their main device was a decrease in teaching cost per student.

Investment Opportunity Set, Product Mix, and the Relationship between Bank CEO Compensation and Risk-Taking

Cluster tools are closed mini production environments that are especially used in the semiconductor industry. They consist of multiple processing chambers. In contrast to single processing tools they can handle multiple lots with different process characteristics at the same time. The major challenge for scheduling cluster tools is the hard to predict process times of even comparable lots as they strongly depend on a changing product mix over the tool. In this paper a mathematical model for the external scheduling of a cluster tool workstation is presented. The goal is to minimize the weighted cycle time by accounting for the changing cycle times of each lot. A MIP model assigns lots to tools of a workstation and determines for each lot the chambers, which are used during the processing steps inside the cluster tool. Finally the developed method is compared with a simulation that uses dispatching strategies.

This article analyzes changes in the product mix by Chilean manufacturing plants in the period 1996–2003. Three quarters of the surviving plants changed the set of products produced and more than three quarters of the exporting plants changed the mix of products they exported during the sample period. Plants that changed their product mix contributed 85% of the aggregate growth in real sales of surviving plants between 1996 and 2003. Finally, and in contrast to the US evidence, there is a negative correlation between revenue per product and the number of products. Apart from this, new evidence consistent with recent models of multi-product heterogeneous firms and trade is provided.

Purpose – In a complex semiconductor manufacturing system (SMS) environment, the implementation of dynamic production scheduling and dispatching strategies is critical for SMS distributed collaborative manufacturing events to make quick and correct decisions. The purpose of this paper is to assist manufacturers in achieving the real time dispatching and obtaining integrated optimization for shop floor production scheduling. Design/methodology/approach – In this paper, an integrated model is designed under assemble to order environment and a framework of a real time dispatching (IRTD) system for production scheduling control is presented accordingly. Both of the scheduling and ordering performances are integrated into the days of inventory based dispatching algorithm, which can deal with the multiple indicators of dynamic scheduling and ordering in this system to generate the “optimal” dispatching policies. Subsequently, the platform of IRTD system is realized with four modules function embedded. Findings – The proposed IRTD system is designed to compare the previous constant work in process method in the experiment, which shows the better performance achievement of the IRTD system for shop floor production dynamic scheduling and order control. The presented framework and algorithm can facilitate real time dispatching information integration to obtain performance metrics in terms of reliability, availability, and maintainability. Research limitations/implications – The presented system can be further developed to generic factory manufacturing with the presented logic and architecture proliferation. Originality/value – The IRTD system can integrate the real time customer demand and work in process information, based on which manufacturers can make correct and timely decisions in solving dispatching strategies and ordering selection within an integrated information system.

Although it is widely acknowledged that protocol design plays a crucial role in the success of clinical research studies, how protocols have changed over time and the impact of these changes on clinical trial performance have never been quantified. To measure protocol design trends, the Tufts Center for the Study of Drug Development analyzed data on 10,038 unique phase 1-4 protocols conducted between 1999 and 2005. Tufts Center for the Study of Drug Development analyzed study conduct performance data on 57 individual phase 2 and 3 protocols administered at US-based investigative sites. The results of this study indicate that the number of unique procedures and the frequency of procedures per protocol have increased at the annual rate of 6.5% and 8.7%, respectively, during the time period measured. Investigative site work burden to administer each protocol increased at an even faster rate of 10.5% between 1999 and 2005. Additionally, during this time period, study conduct performance--that is, cycle time and patient recruitment and retention rates--worsened; and the number of protocol amendments, observed serious adverse events, and length of case report forms increased substantially. Implications of these results for simplifying protocol designs and minimizing negative effects on study conduct performance are discussed.

Modelling complex manufacturing systems using discrete event simulation

In the competitive landscape of furniture manufacturing, the cutting process remains a critical determinant of production lead time and overall operational efficiency. Traditional lot sizing decisions often fail to account for dynamic shop-floor variables, leading to inefficiencies and unpredictable delivery timelines and lead to customer dissatisfaction. This study aims to enhance productivity in furniture manufacturing SMEs by reducing lead time inconsistency and improving on-time delivery performance by optimising cutting operations using discrete-event simulation. The specific objectives include conducting time and motion studies on current cutting processes in SME furniture manufacturing to identify operational inefficiencies and their impact on lead time. To develop a discrete-event simulation model of the existing cutting process, incorporating identified bottlenecks to analyse their contribution to extended lead times. To compare the performance of the optimised simulation model with the baseline process using productivity metrics such as cycle time and throughput. A mixed-methods approach was adopted, combining time studies conducted to pinpoint specific areas of inefficiency, value stream mapping VSM is utilized to map out the production process, and discrete-event simulation using Anylogic software to validate the proposed improvements. Empirical data were collected from a South African SME furniture manufacturing facility. Regression analysis was applied to evaluate the influence of variables such as number of panels, cut length, layout wastage, and operator adjustments on cutting duration. Findings revealed that operator adjustments had the most significant impact on cutting time, with a 32% reduction in adjustments achieved through the proposed optimization model. Simulation results demonstrated a 25% reduction in average cycle time, from 957 seconds to 714 seconds per cut list, validating the model's effectiveness. The linear regression model also enabled accurate forecasting of future demand trends, supporting proactive resource planning.The integration of lean principles with statistical and simulation tools offers a robust framework for optimizing cutting operations in furniture manufacturing. The study recommends the development of an intelligent software system that automates lot sizing and cutting process decisions, thereby reducing lead time and enhancing productivity. This approach holds significant potential for broader application across manufacturing sectors seeking agile and sustainable production systems.

The author studies the specifics of lace in the territory of the South Black Earth Russia in the 19th - early 20th centuries. The author has analyzed the history of lace crafts in the Yelets and Mtsensk districts of the Orlovsk province, and in the Zadonsk district of the Voronezh province. Based on archive materials the article determines such features of lace crafts development as the uniqueness of lace; the dependence of the growth of the influence of buyers on the pace of industry development; presence of the qualitative indicators of the manufacturing process inversely proportional to the quantitative; expanding the range of manufactured lace; the expansion of the sales area of lace; activation of the attention of individuals and public institutions to revive the specificity and individuality of local products lace. It was concluded that the impact of identified features on the pace of development of the lace industry in the South Black Earth Russia and on the development of Russian business in general. Analyzing the history of lace crafts, the author describes the conditions of industrial activity lace, which showed the formation of the capitalist forms of lace makers' work. The features of the capitalist forms of labour which characterized crafts activity are pointed out. The peculiarities of lace sales organization in local and distant markets are studied. In addition to interprovince and interdistrict markets the author investigates the material on exporting goods abroad. The main reasons for the expansion of sales geography determine the change in product mix. The author raises the issue related to the history of the preservation of unique lace made following the traditions of Russian folk art of their ancestors. The problem consisted in the fact that the buyers were not interested in the originality and identity of the goods. As a result, this led to the reduction of the original performance by increasing the amount of work on the standard models.