944 resultados para control system
Resumo:
Esta dissertação trata da importância da Governança Corporativa e da Gestão de Risco para as empresas brasileiras que tem suas ações negociadas nas Bolsas de Valores de Nova York e de São Paulo. Tem como principais objetivos: a avaliação do atual estágio de adequação dessas empresas brasileiras às normas da Lei Sarbanes & Oxley, a confirmação da importância do gerenciamento de risco para a Governança Corporativa, buscando fazer uma associação da ocorrência de perdas patrimoniais com as ferramentas da gestão de risco e das fraudes com a fragilidade de normas de controle interno e com as normas emanadas dos órgãos externos regulatórios. O trabalho acadêmico, um estudo exploratório, teve como ponto de partida uma pesquisa bibliográfica de livros e artigos técnicos versando sobre Governança Corporativa com foco na gestão de riscos. A pesquisa foi feita através da leitura dos relatórios de administração das empresas selecionadas e a aplicabilidade das normas da Lei Sarbanes Oxley. Como conclusão foi possível confirmar com razoável certeza que as grandes perdas, que levaram empresas internacionais a quebra, ocorreram pela falta de uma eficaz gestão de risco ou por um deficiente sistema de controle interno associada a falta de ações preventivas. Por outro lado, apesar dos esforços das empresas brasileiras em se adequar às novas exigências para poder atuar no mercado financeiro do Brasil e dos Estados Unidos da América, parte das empresas pesquisadas ainda se encontra em fase de implementação dos Comitês de Auditoria, de Normas e Procedimentos de Controle Interno e das demais práticas de Gestão Corporativa. Novas pesquisas sobre o tema central deste estudo poderão ensejar no aprofundamento da questão da relação custo x benefício da implantação das práticas de Governança Corporativa e na questão da eficácia dos sistemas corporativos de gerenciamento e controle considerando os custos incorridos em sua implantação e manutenção e os benefícios obtidos. Propõe-se ainda um estudo que busque a revisão das responsabilidades das autoridades reguladoras no que tange ao controle ante e pós-fato. Um dilema a ser resolvido e que deve instigar futuros pesquisadores.(AU)
Resumo:
The application of any e-Solution promises significant returns. In particular, using internet technologies both within enterprises and across the supply (value) chain provides real opportunity, not only for operational improvement but also for innovative strategic positioning. However, significant questions obscure potential investment; how any value will actually be created and, importantly, how this value will be shared across the value chain is not clear. This paper will describe a programme of research that is developing an enterprise simulator that will provide a more fundamental understanding of the impact of e-Solutions across operational supply chains, in terms of both standard operational and financial measures of performance. An efficient supply chain reduces total costs of operations by sharing accurate real-time information and coordinating inter-organizational business processes. This form of electronic link between organizations is known as business-to-business (B2B) e-Business. The financial measures go beyond simple cost calculations to real bottom-line performance by modelling the financial transactions that business processes generate. The paper will show how this enterprise simulator allows for a complete supply chain to be modelled in this way across four key applications: control system design, virtual enterprises, pan-supply-chain performance metrics and supporting e-Supply-chain design methodology.
Resumo:
This article presents some evidence on an aspect of the design of a strategic control system, at the microlevel, within a single organization. The research we report used an ethnographic approach to provide an understanding of strategy formulation. Our aim is to contribute to an area of literature which is of increasing significance, but relatively underdeveloped in terms of the application of in-depth, field-research techniques. We take an intensive look at the manner in which performance measures are formulated, at the microlevel, within a single organization. The article presents, as an in-depth case analysis, the experience of a fisheries holding company in New Zealand. The article recounts the experiences of managers within the organization of the process of identification of such things as critical success factors and key performance indicators (KPIs) and, more broadly, the formulation of a strategic performance measurement system.
Resumo:
This paper is based upon the initial findings of a CIMA research project into the way in which corporate performance measurement systems are influenced by the use of shareholder value management techniques. It compares and contrasts the techniques in use in a sample of 10 companies that either explicitly use shareholder value techniques also known as Value-Based Management (VBM), or explicitly do not use such techniques. The analysis undertaken is based upon the finding of semi-structured interviews with company representatives which formed the first part of the data collection process of the project. The analysis traces the interactions between corporate objectives, decision making criteria, performance measurement systems and executive incentive schemes in order to develop an understanding of the effects of such shareholder value techniques upon corporate behaviour. The literature reviewed suggests that the other aspects of the planning and control system should be aligned with the corporate objectives whether a company has adopted VBM or not. Therefore this research contributes new evidence on the use of VBM techniques in the UK and also more generally on whether VBM and non-VBM companies internal planning and control systems are aligned.
Resumo:
Modern distributed control systems comprise of a set of processors which are interconnected using a suitable communication network. For use in real-time control environments, such systems must be deterministic and generate specified responses within critical timing constraints. Also, they should be sufficiently robust to survive predictable events such as communication or processor faults. This thesis considers the problem of coordinating and synchronizing a distributed real-time control system under normal and abnormal conditions. Distributed control systems need to periodically coordinate the actions of several autonomous sites. Often the type of coordination required is the all or nothing property of an atomic action. Atomic commit protocols have been used to achieve this atomicity in distributed database systems which are not subject to deadlines. This thesis addresses the problem of applying time constraints to atomic commit protocols so that decisions can be made within a deadline. A modified protocol is proposed which is suitable for real-time applications. The thesis also addresses the problem of ensuring that atomicity is provided even if processor or communication failures occur. Previous work has considered the design of atomic commit protocols for use in non time critical distributed database systems. However, in a distributed real-time control system a fault must not allow stringent timing constraints to be violated. This thesis proposes commit protocols using synchronous communications which can be made resilient to a single processor or communication failure and still satisfy deadlines. Previous formal models used to design commit protocols have had adequate state coverability but have omitted timing properties. They also assumed that sites communicated asynchronously and omitted the communications from the model. Timed Petri nets are used in this thesis to specify and design the proposed protocols which are analysed for consistency and timeliness. Also the communication system is mcxielled within the Petri net specifications so that communication failures can be included in the analysis. Analysis of the Timed Petri net and the associated reachability tree is used to show the proposed protocols always terminate consistently and satisfy timing constraints. Finally the applications of this work are described. Two different types of applications are considered, real-time databases and real-time control systems. It is shown that it may be advantageous to use synchronous communications in distributed database systems, especially if predictable response times are required. Emphasis is given to the application of the developed commit protocols to real-time control systems. Using the same analysis techniques as those used for the design of the protocols it can be shown that the overall system performs as expected both functionally and temporally.
Resumo:
This thesis is concerned with various aspects of Air Pollution due to smell, the impact it has on communities exposed to it, the means by which it may be controlled and the manner in which a local authority may investigate the problems it causes. The approach is a practical one drawing on examples occurring within a Local Authority's experience and for that reason the research is anecdotal and is not a comprehensive treatise on the full range of options available. Odour Pollution is not yet a well organised discipline and might be considered esoteric as it is necessary to incorporate elements of science and the humanities. It has been necessary to range widely across a number of aspects of the subject so that discussion is often restricted but many references have been included to enable a reader to pursue a particular point in greater depth. In a `fuzzy' subject there is often a yawning gap separating theory and practice, thus case studies have been used to illustrate the interplay of various disciplines in resolution of a problem. The essence of any science is observation and measurement. Observation has been made of the spread of odour pollution through a community and also of relevant meterological data so that a mathematical model could be constructed and its predictions checked. It has been used to explore the results of some options for odour control. Measurements of odour perception and human behaviour seldom have the precision and accuracy of the physical sciences. However methods of social research enabled individual perception of odour pollution to be quantified and an insight gained into reaction of a community exposed to it. Odours have four attributes that can be measured and together provide a complete description of its perception. No objective techniques of measurement have yet been developed but in this thesis simple, structured procedures of subjective assessment have been improvised and their use enabled the functioning of the components of an odour control system to be assessed. Such data enabled the action of the system to be communicated using terms that are understood by a non specialist audience.
Resumo:
A small lathe has been modified to work under microprocessor control to enhance the facilities which the lathe offers and provide a wider operating range with relevant economic gains. The result of these modifications give better operating system characteristics. A system of electronic circuits have been developed, utilising the latest technology, to replace the pegboard with the associated obsolete electrical components. Software for the system includes control programmes for the implementation of the original pegboard operation and several sample machine code programmes are included, covering a wide spectrum of applications, including diagnostic testing of the control system. It is concluded that it is possible to carry out a low cost retrofit on existing machine tools to enhance their range of capabilities.
Resumo:
This thesis is a theoretical study of the accuracy and usability of models that attempt to represent the environmental control system of buildings in order to improve environmental design. These models have evolved from crude representations of a building and its environment through to an accurate representation of the dynamic characteristics of the environmental stimuli on buildings. Each generation of models has had its own particular influence on built form. This thesis analyses the theory, structure and data of such models in terms of their accuracy of simulation and therefore their validity in influencing built form. The models are also analysed in terms of their compatability with the design process and hence their ability to aid designers. The conclusions are that such models are unlikely to improve environmental performance since: a the models can only be applied to a limited number of building types, b they can only be applied to a restricted number of the characteristics of a design, c they can only be employed after many major environmental decisions have been made, d the data used in models is inadequate and unrepresentative, e models do not account for occupant interaction in environmental control. It is argued that further improvements in the accuracy of simulation of environmental control will not significantly improve environmental design. This is based on the premise that strategic environmental decisions are made at the conceptual stages of design whereas models influence the detailed stages of design. It is hypothesised that if models are to improve environmental design it must be through the analysis of building typologies which provides a method of feedback between models and the conceptual stages of design. Field studies are presented to describe a method by which typologies can be analysed and a theoretical framework is described which provides a basis for further research into the implications of the morphology of buildings on environmental design.
Resumo:
A survey of the existing state-of-the-art of turbine blade manufacture highlights two operations that have not been automated namely that of loading of a turbine blade into an encapsulation die, and that of removing a machined blade from the encapsulation block. The automation of blade decapsulation has not been pursued. In order to develop a system to automate the loading of an encapsulation die a prototype mechanical handling robot has been designed together with a computer controlled encapsulation die. The robot has been designed as a mechanical handling robot of cylindrical geometry, suitable for use in a circular work cell. It is the prototype for a production model to be called `The Cybermate'. The prototype robot is mechanically complete but due to unforeseen circumstances the robot control system is not available (the development of the control system did not form a part of this project), hence it has not been possible to fully test and assess the robot mechanical design. Robot loading of the encapsulation die has thus been simulated. The research work with regard to the encapsulation die has focused on the development of computer controlled, hydraulically actuated, location pins. Such pins compensate for the inherent positional inaccuracy of the loading robot and reproduce the dexterity of the human operator. Each pin comprises a miniature hydraulic cylinder, controlled by a standard bidirectional flow control valve. The precision positional control is obtained through pulsing of the valves under software control, with positional feedback from an 8-bit transducer. A test-rig comprising one hydraulic location pin together with an opposing spring loaded pin has demonstrated that such a pin arrangement can be controlled with a repeatability of +/-.00045'. In addition this test-rig has demonstrated that such a pin arrangement can be used to gauge and compensate for the dimensional error of the component held between the pins, by offsetting the pin datum positions to allow for the component error. A gauging repeatability of +/- 0.00015' was demonstrated. This work has led to the design and manufacture of an encapsulation die comprising ten such pins and the associated computer software. All aspects of the control software except blade gauging and positional data storage have been demonstrated. Work is now required to achieve the accuracy of control demonstrated by the single pin test-rig, with each of the ten pins in the encapsulation die. This would allow trials of the complete loading cycle to take place.
Resumo:
Purpose: The purpose of this paper is to investigate the relations between perceived business uncertainty (PBU), use of external risk management (RM) consultants, formalisation of RM, magnitude of RM methods and perceived organisational outcomes. Design/methodology/approach: This paper is based on a questionnaire survey of members of the Chartered Institute of Management Accountants in the UK. Using AMOS 17.0, the paper tests the strength of the direct and indirect effects among the variables and explores the fit of the overall path model. Findings: The results indicate significant and positive associations exist between the extent of PBU and the level ofRMformalisation, as well as between the level ofRMformalisation and the magnitude of RMmethods adopted. The use of externalRMconsultants is also found to have a significant and positive impact on the magnitude of RM methods adopted. Finally, both the extent of RM formalisation and the magnitude of RM methods adopted are seen to be significantly associated with overall improvement in organisational outcomes. Research limitations/implications: The study uses perceptual measures of the level of business uncertainty, usage of RM and organisational outcomes. Further, the respondents are members of a management accounting professional body and the views of other managers, such as risk managers, who are also important to the governance process are not incorporated. Originality/value: This study provides empirical evidence on the impact ofRMdesign and usage on improvements in organisational outcomes. It contributes to the RM literature where empirical research is needed in order to be comparable with the traditional management control system literature.
Resumo:
Definitions and perceptions of the role and styles of risk management, and performance management/strategic control systems have evolved over time, but it can be argued that risk management is primarily concerned with ensuring the achievement of strategic objectives. This paper shows the extent of overlap between a broad-based view of risk management, namely Enterprise Risk Management (ERM), and the balanced scorecard, which is a widely used strategic control system. A case study of one of the UK's largest retailers, Tesco plc, is used to show how ERM can be introduced as part of an existing strategic control system. The case demonstrates that, despite some differences in lines of communications, the strategic controls and risk controls can be used to achieve a common objective. Adoption of such an integrated approach, however, has implications for the profile of risk and the overall risk culture within an organisation.
Resumo:
Purpose: Evidence exists for an additional inhibitory accommodative control system mediated by the sympathetic branch of the autonomic nervous system (ANS). This work aims to show the relative prevalence of sympathetic inhibition in young emmetropic and myopic adults, and to evaluate the effect of sympathetic facility on accommodative and oculomotor function. Methods: Profiling of ciliary muscle innervation was carried out in 58 young adult subjects (30 emmetropes, 14 early onset myopes, 14 late onset myopes) by examining post-task open-loop accommodation responses, recorded continuously by a modified open-view infrared optometer. Measurements of amplitude of accommodation, tonic accommodation, accommodative lag at near, AC/A ratio, and heterophoria at distance and near were made to establish a profile of oculomotor function. Results: Evidence of sympathetic inhibitory facility in ciliary smooth muscle was observed in 27% of emmetropes, 21% of early-onset myopes and 29% of late-onset myopes. Twenty-six percent of all subjects demonstrated access to sympathetic facility. Closed-loop oculomotor function did not differ significantly between subjects with sympathetic facility, and those with sympathetic deficit. Conclusions: Emmetropic and myopic groups cannot be distinguished in terms of the relative proportions having access to sympathetic inhibition. Presence of sympathetic innervation does not have a significant effect on accommodative function under closed-loop viewing conditions. © 2005 Elsevier Ltd. All rights reserved.
Resumo:
In recent years the science of risk management has developed substantially, and many large companies and public sector organisations have established separate risk functions employing specialist staff. The reasons behind such developments are varied but they denote an increasing consciousness of a need to actively manage risks and, in compliance with regulations on corporate governance, ensure that an effective internal control system is in operation.
Resumo:
Swallowable capsule endoscopy is used for non-invasive diagnosis of some gastrointestinal (GI) organs. However, control over the position of the capsule is a major unresolved issue. This study presents a design for steering the capsule based on magnetic levitation. The levitation is stabilized with the aid of a computer-aided feedback control system and diamagnetism. Peristaltic and gravitational forces to be overcome were calculated. A levitation setup was built to analyze the feasibility of using Hall Effect sensors to locate the in- vivo capsule. CAD software Maxwell 3D (Ansoft, Pittsburgh, PA) was used to determine the dimensions of the resistive electromagnets required for levitation and the feasibility of building them was examined. Comparison based on design complexity was made between positioning the patient supinely and upright.
Resumo:
The sheer volume of citizen weather data collected and uploaded to online data hubs is immense. However as with any citizen data it is difficult to assess the accuracy of the measurements. Within this project we quantify just how much data is available, where it comes from, the frequency at which it is collected, and the types of automatic weather stations being used. We also list the numerous possible sources of error and uncertainty within citizen weather observations before showing evidence of such effects in real data. A thorough intercomparison field study was conducted, testing popular models of citizen weather stations. From this study we were able to parameterise key sources of bias. Most significantly the project develops a complete quality control system through which citizen air temperature observations can be passed. The structure of this system was heavily informed by the results of the field study. Using a Bayesian framework the system learns and updates its estimates of the calibration and radiation-induced biases inherent to each station. We then show the benefit of correcting for these learnt biases over using the original uncorrected data. The system also attaches an uncertainty estimate to each observation, which would provide real world applications that choose to incorporate such observations with a measure on which they may base their confidence in the data. The system relies on interpolated temperature and radiation observations from neighbouring professional weather stations for which a Bayesian regression model is used. We recognise some of the assumptions and flaws of the developed system and suggest further work that needs to be done to bring it to an operational setting. Such a system will hopefully allow applications to leverage the additional value citizen weather data brings to longstanding professional observing networks.