Aspects of design for a spare parts provisioning system

This thesis describes an investigation by the author into the spares operation of compare BroomWade Ltd. Whilst the complete system, including the warehousing and distribution functions, was investigated, the thesis concentrates on the provisioning aspect of the spares supply problem. Analysis of the historical data showed the presence of significant fluctuations in all the measures of system performance. Two Industrial Dynamics simulation models were developed to study this phenomena. The models showed that any fluctuation in end customer demand would be amplified as it passed through the distributor and warehouse stock control systems. The evidence from the historical data available supported this view of the system's operation. The models were utilised to determine which parts of the total system could be expected to exert a critical influence on its performance. The lead time parameters of the supply sector were found to be critical and further study showed that the manner in which the lead time changed with work in progress levels was also an important factor. The problem therefore resolved into the design of a spares manufacturing system. Which exhibited the appropriate dynamic performance characteristics. The gross level of entity presentation, inherent in the Industrial Dynamics methodology, was found to limit the value of these models in the development of detail design proposals. Accordingly, an interacting job shop simulation package was developed to allow detailed evaluation of organisational factors on the performance characteristics of a manufacturing system. The package was used to develop a design for a pilot spares production unit. The need for a manufacturing system to perform successfully under conditions of fluctuating demand is not limited to the spares field. Thus, although the spares exercise provides an example of the approach, the concepts and techniques developed can be considered to have broad application throughout batch manufacturing industry.

Automation, rationalisation and concentration : a case study in the British chemical industry

This thesis is based upon a case study of the adoption of digital, electronic, microprocessor-based control systems by Albright & Wilson Limited - a UK chemical producer. It offers an explanation of the company's changing technology policy between 1978 and 1981, by examining its past development, internal features and industrial environment. Part One of the thesis gives an industry-level analysis which relates the development of process control technology to changes in the economic requirements of production . The rapid diffusion of microcomputers and other microelectronic equipment in the chemical industry is found to be a response to general need to raise the efficiency of all processes, imposed by the economic recession following 1973. Part Two examines the impaot of these technical and eoonomic ohanges upon Albright & Wilson Limited. The company's slowness in adopting new control technology is explained by its long history in which trends are identified whlich produced theconservatism of the 1970s. By contrast, a study of Tenneco Incorporated, a much more successful adoptor of automating technology, is offered with an analysis of the new technology policy of adoption of such equipment which it imposed upon Albright & Wilson, following the latter's takeover by Tenneco in 1978. Some indications of the consequences by this new policy of widespread adoptions of microprocessor-based control equipment are derived from a study of the first Albright & Wilson plant to use such equipment. The thesis concludes that companies which fail to adopt rapidly the new control technology may not survive in the recessionary environment, the long- established British companies may lack the flexibility to make such necessary changes and that multi-national companies may have an important role jn the planned transfer and adoption of new production technology through their subsidiaries in the UK.

A contingency theory perspective on the risk management control system within Birmingham City Council

In recent years the topic of risk management has moved up the agenda of both government and industry, and private sector initiatives to improve risk and internal control systems have been mirrored by similar promptings for change in the public sector. Both regulators and practitioners now view risk management as an integral part of the process of corporate governance, and an aid to the achievement of strategic objectives. The paper uses case study material on the risk management control system at Birmingham City Council to extend existing theory by developing a contingency theory for the public sector. The case demonstrates that whilst the structure of the control system fits a generic model, the operational details indicate that controls are contingent upon three core variables—central government policies, information and communication technology and organisational size. All three contingent variables are suitable for testing the theory across the broader public sector arena.

Logical Models of Composite Dynamic Objects Control

The questions of designing multicriteria control systems on the basis of logic models of composite dynamic objects are considered.

The Complex Unified Evolutionary Approach to the Creation of the Multilevel Distributed Control System of a Gas-transport Company

The objects of a large-scale gas-transport company (GTC) suggest a complex unified evolutionary approach, which covers basic building concepts, up-to-date technologies, models, methods and means that are used in the phases of design, adoption, maintenance and development of the multilevel automated distributed control systems (ADCS).. As a single methodological basis of the suggested approach three basic Concepts, which contain the basic methodological principles and conceptual provisions on the creation of distributed control systems, were worked out: systems of the lower level (ACS of the technological processes based on up-to-date SCADA), of the middle level (ACS of the operative-dispatch production control based on MES-systems) and of the high level (business process control on the basis of complex automated systems ERP).

A mixture density network approach to modelling and exploiting uncertainty in nonlinear control problems

In nonlinear and stochastic control problems, learning an efficient feed-forward controller is not amenable to conventional neurocontrol methods. For these approaches, estimating and then incorporating uncertainty in the controller and feed-forward models can produce more robust control results. Here, we introduce a novel inversion-based neurocontroller for solving control problems involving uncertain nonlinear systems which could also compensate for multi-valued systems. The approach uses recent developments in neural networks, especially in the context of modelling statistical distributions, which are applied to forward and inverse plant models. Provided that certain conditions are met, an estimate of the intrinsic uncertainty for the outputs of neural networks can be obtained using the statistical properties of networks. More generally, multicomponent distributions can be modelled by the mixture density network. Based on importance sampling from these distributions a novel robust inverse control approach is obtained. This importance sampling provides a structured and principled approach to constrain the complexity of the search space for the ideal control law. The developed methodology circumvents the dynamic programming problem by using the predicted neural network uncertainty to localise the possible control solutions to consider. A nonlinear multi-variable system with different delays between the input-output pairs is used to demonstrate the successful application of the developed control algorithm. The proposed method is suitable for redundant control systems and allows us to model strongly non-Gaussian distributions of control signal as well as processes with hysteresis. © 2004 Elsevier Ltd. All rights reserved.

High-Order Control Variations and Small-Time Local Controllability

The importance of “control variations” for obtaining local approximations of the reachable set of nonlinear control systems is well known. Heuristically, if one can construct control variations in all possible directions, then the considered control system is small-time locally controllable (STLC). Two concepts of control variations of higher order are introduced for the case of smooth control systems. The relation between these variations and the small-time local controllability is studied and a new sufficient STLC condition is proved.

Large volume metrology technologies for the light controlled factory

In the Light Controlled Factory part-to-part assembly and reduced weight will be enabled through the use of predictive fitting processes; low cost high accuracy reconfigurable tooling will be made possible by active compensation; improved control will allow accurate robotic machining; and quality will be improved through the use of traceable uncertainty based quality control throughout the production system. A number of challenges must be overcome before this vision will be realized; 1) controlling industrial robots for accurate machining; 2) compensation of measurements for thermal expansion; 3) Compensation of measurements for refractive index changes; 4) development of Embedded Metrology Tooling for in-tooling measurement and active tooling compensation; and 5) development of Software for the Planning and Control of Integrated Metrology Networks based on Quality Control with Uncertainty Evaluation and control systems for predictive processes. This paper describes how these challenges are being addressed, in particular the central challenge of developing large volume measurement process models within an integrated dimensional variation management (IDVM) system.

Experimental comparison of dynamic tracking performance of iGPS and laser tracker

External metrology systems are increasingly being integrated with traditional industrial articulated robots, especially in the aerospace industries, to improve their absolute accuracy for precision operations such as drilling, machining and jigless assembly. While currently most of the metrology assisted robotics control systems are limited in their position update rate, such that the robot has to be stopped in order to receive a metrology coordinate update, some recent efforts are addressed toward controlling robots using real-time metrology data. The indoor GPS is one of the metrology systems that may be used to provide real-time 6DOF data to a robot controller. Even if there is a noteworthy literature dealing with the evaluation of iGPS performance, there is, however, a lack of literature on how well the iGPS performs under dynamic conditions. This paper presents an experimental evaluation of the dynamic measurement performance of the iGPS, tracking the trajectories of an industrial robot. The same experiment is also repeated using a laser tracker. Besides the experiment results presented, this paper also proposes a novel method for dynamic repeatability comparisons of tracking instruments. © 2011 Springer-Verlag London Limited.

Optimization of adaptive traffic signal control with transit signal priority at isolated intersections using parallel genetic algorithms

Optimization of adaptive traffic signal timing is one of the most complex problems in traffic control systems. This dissertation presents a new method that applies the parallel genetic algorithm (PGA) to optimize adaptive traffic signal control in the presence of transit signal priority (TSP). The method can optimize the phase plan, cycle length, and green splits at isolated intersections with consideration for the performance of both the transit and the general vehicles. Unlike the simple genetic algorithm (GA), PGA can provide better and faster solutions needed for real-time optimization of adaptive traffic signal control. ^ An important component in the proposed method involves the development of a microscopic delay estimation model that was designed specifically to optimize adaptive traffic signal with TSP. Macroscopic delay models such as the Highway Capacity Manual (HCM) delay model are unable to accurately consider the effect of phase combination and phase sequence in delay calculations. In addition, because the number of phases and the phase sequence of adaptive traffic signal may vary from cycle to cycle, the phase splits cannot be optimized when the phase sequence is also a decision variable. A "flex-phase" concept was introduced in the proposed microscopic delay estimation model to overcome these limitations. ^ The performance of PGA was first evaluated against the simple GA. The results show that PGA achieved both faster convergence and lower delay for both under- or over-saturated traffic conditions. A VISSIM simulation testbed was then developed to evaluate the performance of the proposed PGA-based adaptive traffic signal control with TSP. The simulation results show that the PGA-based optimizer for adaptive TSP outperformed the fully actuated NEMA control in all test cases. The results also show that the PGA-based optimizer was able to produce TSP timing plans that benefit the transit vehicles while minimizing the impact of TSP on the general vehicles. The VISSIM testbed developed in this research provides a powerful tool to design and evaluate different TSP strategies under both actuated and adaptive signal control. ^

Manufacturing Performance Reporting For Continuous Quality Improvement

Recently many plants have implemented the new manufacturing strategy of continuous quality improvement. The central hypothesis in this paper is that the implementation of a policy of continuous quality improvement results in a shift in the management control system. This article tests this hypothesis by examining the shop floor reporting policies of forty-two plants located in the United States. The paper documents that the extent of information concerning the current status of manufacturing, such as charts on defect rates or schedule compliance and productivity information, provided to workers on the shop floor is positively related to the implementation of continuous quality improvement programs.

Systems Modeling of Lung Cancer Screening Programs to Improve Quality

Thesis (Master's)--University of Washington, 2016-08

Iluminação em ambientes fabris: otimização e análise técnica-e-económica

Esta Dissertação aborda a temática da eficiência energética em sistemas de iluminação fabris. Desde os primórdios da história da humanidade que a iluminação tem representado um papel importante. Não só garante condições de segurança, como começou por ser o intuito primordial das fogueiras pré-históricas, traduzindo-se num elemento de conforto. Atualmente seria impensável conceber as mais diversas atividades económicas e produtivas de um país sem iluminação. Nesse sentido a iluminação representa também um elemento fomentador de produtividade. Não é bem conhecido o impacto que a iluminação tem nos custos operacionais de uma unidade fabril. Principalmente por ser difícil de quantificar separadamente na fatura de eletricidade qual a percentagem correspondente à iluminação. Tipicamente estes custos podem ascender a 20% do orçamento global da autarquia em países desenvolvidos. Por esse motivo, o sector da iluminação tem investido esforço no sentido de promover melhores soluções de iluminação capazes de por um lado de satisfazer os requisitos do espaço a iluminar, e por outro propiciar soluções eficientes do ponto de vista energético. Estas soluções assentam essencialmente no uso de dispositivos mais eficientes (como por exemplo os LED´s ou as lâmpadas compactas fluorescentes) bem como em estratégias de controlo eficientes baseadas em dados sensoriais (como por exemplo deteção de movimento/presença). A combinação destas estratégias permite reduzir os consumos em cerca de 80% quando comparadas com soluções passivas. A empresa Amorim Cork Research Lda. é uma empresa prestadora de serviços ao universo das empresas da Corticeira Amorim, uma das maiores multinacionais de origem portuguesa. Teve origem no negócio da cortiça, em 1870, sendo hoje líder destacada no sector a nível mundial. Dada a dimensão da empresa e a sua subdivisão em várias Unidades Industriais com requisitos individuais, será expectável que a iluminação represente uma parte significativa da fatura de eletricidade. Atualmente, os vários setores encontram-se equipados com soluções de iluminação diferentes, na sua maioria empregando tecnologias passivas, noutros casos com dispositivos eficientes. Há algum interesse em migrar para soluções mais eficientes, em parte suportadas em DALI (com interface de comunicação PLC ou Zigbee).

Sistema de emulação de aerogeradores para aplicação em geração distribuída de energia elétrica

Power generation from alternative sources is at present the subject of numerous research and development in science and industry. Wind energy stands out in this scenario as one of the most prominent alternative in the generation of electricity, by its numerous advantages. In research works, computer reproduction and experimental behavior of a wind turbine are very suitable tools for the development and study of new technologies and the use of wind potential of a given region. These tools generally are desired to include simulation of mechanical and electrical parameters that directly affect the energy conversion. This work presents the energy conversion process in wind systems for power generation, in order to develop a tool for wind turbine emulation testing experimental, using LabVIEW® software. The purpose of this tool is to emulate the torque developed in an axis wind turbine. The physical setup consists of a three phase induction motor and a permanent magnet synchronous generator, which are evaluated under different wind speed conditions. This tool has the objective to be flexible to other laboratory arrangements, and can be used in other wind power generation structures in real time. A modeling of the wind power system is presented, from the turbine to the electrical generator. A simulation tool is developed using Matlab/Simulink® with the purpose to pre-validate the experiment setup. Finally, the design is implemented in a laboratory setup.

Pressure management in water distribution systems: current status, proposals, and future trends

Pressure management (PM) is commonly used in water distribution systems (WDSs). In the last decade, a strategic objective in the field has been the development of new scientific and technical methods for its implementation. However, due to a lack of systematic analysis of the results obtained in practical cases, progress has not always been reflected in practical actions. To address this problem, this paper provides a comprehensive analysis of the most innovative issues related to PM. The methodology proposed is based on a case-study comparison of qualitative concepts that involves published work from 140 sources. The results include a qualitative analysis covering four aspects: (1) the objectives yielded by PM; (2) types of regulation, including advanced control systems through electronic controllers; (3) new methods for designing districts; and (4) development of optimization models associated with PM. The evolution of the aforementioned four aspects is examined and discussed. Conclusions regarding the current status of each factor are drawn and proposals for future research outlined