884 resultados para Planning and control
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Texas State Department of Highways and Public Transportation, Transportation Planning Division, Austin
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Vol. 7: second ed., 1975.
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This research explores the links between the strategies adopted by companies and the mechanisms used to control the organisation. This is not seen as a one way process with the control system following from the strategy but rather as an interactive process between the control systems, the environment and the business strategy. The main proposition of the research, derived from a review of the relevant literature, is that the dimensions of Business Pro-Activity and Environmental Change provide a plausible explanation of the reasons why companies need to adopt different strategies in order to be successful in different markets. A model is proposed which links these dimensions with the business strategy, organisational structure, strategic planning system and management control systems. The model is used as a framework for analysing four companies in order to further our understanding of these interactions and the mechanisms which act to both promote and resist change. Whilst it is not suggested that the model in its present form is a perfect instrument it has, during the course of this research, proved to be an appropriate framework for analysing the various mechanisms used by four companies to formulate and implement their strategies. The research reveals that these should not be viewed independently but as a balanced system.
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Computerised production control developments have concentrated on Manufacturing Resources Planning (MRP II) systems. The literature suggests however, that despite the massive investment in hardware, software and management education, successful implementation of such systems in manufacturing industries has proved difficult. This thesis reviews the development of production planning and control systems, in particular, investigates the causes of failures in implementing MRP/MRP II systems in industrial environments and argues that the centralised and top-down planning structure, as well as the routine operational methodology of such systems, is inherently prone to failure. The thesis reviews the control benefits of cellular manufacturing systems but concludes that in more dynamic manufacturing environments, techniques such as Kanban are inappropriate. The basic shortcomings of MRP II systems are highlighted and a new enhanced operational methodology based on distributed planning and control principles is introduced. Distributed Manufacturing Resources Planning (DMRP), was developed as a capacity sensitive production planning and control solution for cellular manufacturing environments. The system utilises cell based, independently operated MRP II systems, integrated into a plant-wide control system through a Local Area Network. The potential benefits of adopting the system in industrial environments is discussed and the results of computer simulation experiments to compare the performance of the DMRP system against the conventional MRP II systems presented. DMRP methodology is shown to offer significant potential advantages which include ease of implementation, cost effectiveness, capacity sensitivity, shorter manufacturing lead times, lower working in progress levels and improved customer service.
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This paper presents a new, dynamic feature representation method for high value parts consisting of complex and intersecting features. The method first extracts features from the CAD model of a complex part. Then the dynamic status of each feature is established between various operations to be carried out during the whole manufacturing process. Each manufacturing and verification operation can be planned and optimized using the real conditions of a feature, thus enhancing accuracy, traceability and process control. The dynamic feature representation is complementary to the design models used as underlining basis in current CAD/CAM and decision support systems. © 2012 CIRP.
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A dolgozat a visszutas logisztikát, az újrahasznosítást igyekszik beilleszteni a vállalati termeléstervezés keretei közé. A szükséglettervezési rendszerek (material requirements planning, MRP) célja a készletek és beszerzendő anyagok, alkatrészek időben ütemezett gyártásának és beszerzésének megtervezése. A klasszikus MRP rendszereket az utóbbi időben próbálja a tudomány az újrahasznosítással kibővíteni. Mivel ebben az esetben az új, és újrafelhasználható anyagokat külön kell nyilvántartani, ezért az MRP-táblák és készletek növekednek. A rendelési tételnagyságok meghatározása is nehezebb, összetettebb tételnagysághoz vezet. A dolgozatban egy visszutas logisztikai készletmodellt ismertetünk, valamint annak dinamikus kiterjesztését, amely alapja lehet az SAP-ba beépíthető rendelés állomány meghatározó heurisztikának. ____ The aim of the paper is to extend production planning with reverse logistics and reuse. Material requirements planning (MRP) systems plan and control invetory levels and purchasing activities of the firm. In the last decade scientists on this field try to involve reverse logistics activities in MRP systems. Size of MRP-tables is growing in this case because of the alternative use of newly purchased products and reusable old items. Determination of order quantities will be more complex with these two modes of material supplies. An EOQ-type reverse logistics model is presented in the paper with a dynamic lot size generalization. The generalized model can be seen as a basic model to build in production planning and control system like SAP.
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In compliance with the economic internationalization movement and the development of Asia-Pacific Regional Operation Center (APROC) in Taiwan, international business has become more and more important. To sustain favorable trade balances every year and the promotion of APROC in Taiwan, more and more talent with knowledge and skills of Business English are needed. As a consequence, it is necessary to make Business English curriculum appropriate to meet the emerging needs.^ Two groups, experimental and control, received the revised or traditional Business English course to answer the question, "Does the Business English curriculum at Tainan Woman's College of Arts & Technology (TWCAT) meet the needs of students?" Ninety-five subjects were randomly selected from the commercial departments at TWCAT and then randomly assigned to the two groups. In addition, the Business English scores of the subjects' previous semester were collected and analyzed to justify the random selection and assignment. The finding was that their initial equivalence was proved.^ A questionnaire for students and another one for the business community were administered to facilitate data collection and analysis. The results of the questionnaires were used to modify the curriculum content of Business English.^ A final-term examination was given to the subjects at the end of the pilot study of Business English in early May of 1998. The resulting scores of the examination were used to determine if there was a significant difference in learning achievement between the students of the two groups.^ Using Independent Samples Test, significant results indicated that the experimental group had higher level of learning Business English than the control group. The finding supports the hypothesis of this study.^ Recommendations based on these results are that the revised curriculum be adapted and used by TWCAT because it better meets student needs. ^
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Introduction: Seeking preconception care is recognized as an important health behavior for women with preexisting diabetes. Yet many women with diabetes do not seek care or advice until after they are pregnant, and many enter pregnancy with suboptimal glycemic control. This study explored the attitudes about pregnancy and preconception care seeking in a group of nonpregnant women with type 1 diabetes mellitus. Methods: In-depth semistructured interviews were completed with 14 nonpregnant women with type 1 diabetes. Results: Analysis of the interview data revealed 4 main themes: 1) the emotional complexity of childbearing decisions, 2) preferences for information related to pregnancy, 3) the importance of being known by your health professional, and 4) frustrations with the medical model of care. Discussion: These findings raise questions about how preconception care should be provided to women with diabetes and highlight the pivotal importance of supportive, familiar relationships between health professionals and women with diabetes in the provision of individualized care and advice. By improving the quality of relationships and communication between health care providers and patients, we will be better able to provide care and advice that is perceived as relevant to the individual, whatever her stage of family planning. © 2012 by the American College of Nurse-Midwives.
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Motion planning, or trajectory planning, commonly refers to a process of converting high-level task specifications into low-level control commands that can be executed on the system of interest. For different applications, the system will be different. It can be an autonomous vehicle, an Unmanned Aerial Vehicle(UAV), a humanoid robot, or an industrial robotic arm. As human machine interaction is essential in many of these systems, safety is fundamental and crucial. Many of the applications also involve performing a task in an optimal manner within a given time constraint. Therefore, in this thesis, we focus on two aspects of the motion planning problem. One is the verification and synthesis of the safe controls for autonomous ground and air vehicles in collision avoidance scenarios. The other part focuses on the high-level planning for the autonomous vehicles with the timed temporal constraints. In the first aspect of our work, we first propose a verification method to prove the safety and robustness of a path planner and the path following controls based on reachable sets. We demonstrate the method on quadrotor and automobile applications. Secondly, we propose a reachable set based collision avoidance algorithm for UAVs. Instead of the traditional approaches of collision avoidance between trajectories, we propose a collision avoidance scheme based on reachable sets and tubes. We then formulate the problem as a convex optimization problem seeking control set design for the aircraft to avoid collision. We apply our approach to collision avoidance scenarios of quadrotors and fixed-wing aircraft. In the second aspect of our work, we address the high level planning problems with timed temporal logic constraints. Firstly, we present an optimization based method for path planning of a mobile robot subject to timed temporal constraints, in a dynamic environment. Temporal logic (TL) can address very complex task specifications such as safety, coverage, motion sequencing etc. We use metric temporal logic (MTL) to encode the task specifications with timing constraints. We then translate the MTL formulae into mixed integer linear constraints and solve the associated optimization problem using a mixed integer linear program solver. We have applied our approach on several case studies in complex dynamical environments subjected to timed temporal specifications. Secondly, we also present a timed automaton based method for planning under the given timed temporal logic specifications. We use metric interval temporal logic (MITL), a member of the MTL family, to represent the task specification, and provide a constructive way to generate a timed automaton and methods to look for accepting runs on the automaton to find an optimal motion (or path) sequence for the robot to complete the task.
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Despite the extensive implementation of Superstreets on congested arterials, reliable methodologies for such designs remain unavailable. The purpose of this research is to fill the information gap by offering reliable tools to assist traffic professionals in the design of Superstreets with and without signal control. The entire tool developed in this thesis consists of three models. The first model is used to determine the minimum U-turn offset length for an Un-signalized Superstreet, given the arterial headway distribution of the traffic flows and the distribution of critical gaps among drivers. The second model is designed to estimate the queue size and its variation on each critical link in a signalized Superstreet, based on the given signal plan and the range of observed volumes. Recognizing that the operational performance of a Superstreet cannot be achieved without an effective signal plan, the third model is developed to produce a signal optimization method that can generate progression offsets for heavy arterial flows moving into and out of such an intersection design.
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In the globalizing world, knowledge and information (and the social and technological settings for their production and communication) are now seen as keys to economic prosperity. The economy of a knowledge city creates value-added products using research, technology, and brainpower. The social benefit of knowledge-based urban development (KBUD); however, extends beyond aggregate economic growth.
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Information and communication technologies (ICTs) had occupied their position on knowledge management and are now evolving towards the era of self-intelligence (Klosterman, 2001). In the 21st century ICTs for urban development and planning are imperative to improve the quality of life and place. This includes the management of traffic, waste, electricity, sewerage and water quality, monitoring fire and crime, conserving renewable resources, and coordinating urban policies and programs for urban planners, civil engineers, and government officers and administrators. The handling of tasks in the field of urban management often requires complex, interdisciplinary knowledge as well as profound technical information. Most of the information has been compiled during the last few years in the form of manuals, reports, databases, and programs. However frequently, the existence of these information and services are either not known or they are not readily available to the people who need them. To provide urban administrators and the public with comprehensive information and services, various ICTs are being developed. In early 1990s Mark Weiser (1993) proposed Ubiquitous Computing project at the Xerox Palo Alto Research Centre in the US. He provides a vision of a built environment which digital networks link individual residents not only to other people but also to goods and services whenever and wherever they need (Mitchell, 1999). Since then the Republic of Korea (ROK) has been continuously developed national strategies for knowledge based urban development (KBUD) through the agenda of Cyber Korea, E-Korea and U-Korea. Among abovementioned agendas particularly the U-Korea agenda aims the convergence of ICTs and urban space for a prosperous urban and economic development. U-Korea strategies create a series of U-cities based on ubiquitous computing and ICTs by a means of providing ubiquitous city (U-city) infrastructure and services in urban space. The goals of U-city development is not only boosting the national economy but also creating value in knowledge based communities. It provides opportunity for both the central and local governments collaborate to U-city project, optimize information utilization, and minimize regional disparities. This chapter introduces the Korean-led U-city concept, planning, design schemes and management policies and discusses the implications of U-city concept in planning for KBUD.