684 research outputs found

    An intelligent knowledge based cost modelling system for innovative product development

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    This research work aims to develop an intelligent knowledge-based system for product cost modelling and design for automation at an early design stage of the product development cycle, that would enable designers/manufacturing planners to make more accurate estimates of the product cost. Consequently, a quicker response to customers’ expectations. The main objectives of the research are to: (1) develop a prototype system that assists an inexperienced designer to estimate the manufacturing cost of the product, (2) advise designers on how to eliminate design and manufacturing related conflicts that may arise during the product development process, (3) recommend the most economic assembly technique for the product in order to consider this technique during the design process and provide design improvement suggestions to simplify the assembly operations (i.e. to provide an opportunity for designers to design for assembly (DFA)), (4) apply a fuzzy logic approach to certain cases, and (5) evaluate the developed prototype system through five case studies. The developed system for cost modelling comprises of a CAD solid modelling system, a material selection module, knowledge-based system (KBS), process optimisation module, design for assembly module, cost estimation technique module, and a user interface. In addition, the system encompasses two types of databases, permanent (static) and temporary (dynamic). These databases are categorised into five separate groups of database, Feature database, Material database, Machinability database, Machine database, and Mould database. The system development process has passed through four major steps: firstly, constructing the knowledge-based and process optimisation system, secondly developing a design for assembly module. Thirdly, integrating the KBS with both material selection database and a CAD system. Finally, developing and implementing a ii fuzzy logic approach to generate reliable estimation of cost and to handle the uncertainty in cost estimation model that cannot be addressed by traditional analytical methods. The developed system has, besides estimating the total cost of a product, the capability to: (1) select a material as well as the machining processes, their sequence and machining parameters based on a set of design and production parameters that the user provides to the system, and (2) recommend the most economic assembly technique for a product and provide design improvement suggestion, in the early stages of the design process, based on a design feasibility technique. It provides recommendations when a design cannot be manufactured with the available manufacturing resources and capabilities. In addition, a feature-by-feature cost estimation report was generated using the system to highlight the features of high manufacturing cost. The system can be applied without the need for detailed design information, so that it can be implemented at an early design stage and consequently cost redesign, and longer lead-time can be avoided. One of the tangible advantages of this system is that it warns users of features that are costly and difficult to manufacture. In addition, the system is developed in such a way that, users can modify the product design at any stage of the design processes. This research dealt with cost modelling of both machined components and injection moulded components. The developed cost effective design environment was evaluated on real products, including a scientific calculator, a telephone handset, and two machined components. Conclusions drawn from the system indicated that the developed prototype system could help companies reducing product cost and lead time by estimating the total product cost throughout the entire product development cycle including assembly cost. Case studies demonstrated that designing a product using the developed system is more cost effective than using traditional systems. The cost estimated for a number of products used in the case studies was almost 10 to 15% less than cost estimated by the traditional system since the latter does not take into consideration process optimisation, design alternatives, nor design for assembly issue

    Wide-Area Time-Synchronized Closed-Loop Control of Power Systems And Decentralized Active Distribution Networks

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    The rapidly expanding power system grid infrastructure and the need to reduce the occurrence of major blackouts and prevention or hardening of systems against cyber-attacks, have led to increased interest in the improved resilience of the electrical grid. Distributed and decentralized control have been widely applied to computer science research. However, for power system applications, the real-time application of decentralized and distributed control algorithms introduce several challenges. In this dissertation, new algorithms and methods for decentralized control, protection and energy management of Wide Area Monitoring, Protection and Control (WAMPAC) and the Active Distribution Network (ADN) are developed to improve the resiliency of the power system. To evaluate the findings of this dissertation, a laboratory-scale integrated Wide WAMPAC and ADN control platform was designed and implemented. The developed platform consists of phasor measurement units (PMU), intelligent electronic devices (IED) and programmable logic controllers (PLC). On top of the designed hardware control platform, a multi-agent cyber-physical interoperability viii framework was developed for real-time verification of the developed decentralized and distributed algorithms using local wireless and Internet-based cloud communication. A novel real-time multiagent system interoperability testbed was developed to enable utility independent private microgrids standardized interoperability framework and define behavioral models for expandability and plug-and-play operation. The state-of-theart power system multiagent framework is improved by providing specific attributes and a deliberative behavior modeling capability. The proposed multi-agent framework is validated in a laboratory based testbed involving developed intelligent electronic device prototypes and actual microgrid setups. Experimental results are demonstrated for both decentralized and distributed control approaches. A new adaptive real-time protection and remedial action scheme (RAS) method using agent-based distributed communication was developed for autonomous hybrid AC/DC microgrids to increase resiliency and continuous operability after fault conditions. Unlike the conventional consecutive time delay-based overcurrent protection schemes, the developed technique defines a selectivity mechanism considering the RAS of the microgrid after fault instant based on feeder characteristics and the location of the IEDs. The experimental results showed a significant improvement in terms of resiliency of microgrids through protection using agent-based distributed communication

    Flexibility of Electric Power Systems by Network Planning and Service Provision: Challenges for Energy Transition

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    In recent years, the electric power system is meeting a radical evolution due to the increasing penetration of Renewable Energy Sources (RESs). These have a relevant impact on most of the applications concerning the electrical network, such as the electricity markets, regulation services provision and the grid management and protection. However, the deep RESs deployment is the answer that countries all over the world are pursuing to fight climate change according to the Sustainable Development Goals (SDGs) adopted by the United Nations (UN). This evolution requires a great development of the network, that has to host a large quantity of new RESs, and the establishment of new strategies to deal with new challenges. More and more reserves for regulation services are pursued by units that couldn’t provide dispatching services until now, namely small-sized plants and RESs, but also load and storage systems. The demand has become increasingly more active since it has made possible a contribution to instability issues by varying their power profile for a certain amount of time without compromising the final user’s comfort, which means being flexible. As a result, a huge amount of new generation units and load units have started to provide dispatching services by participating to the electricity markets. This condition has led to the need of the improvement of the communication systems among all the actors in the process of power transmission alongside grid balancing, including the Transmission System Operator (TSO), the Distribution System Operators (DSOs), generation, load units and other data aggregators. The observability of the system is essential to forecast load and generation profiles in order to provide a suitable balancing service and to guarantee the reliability, safety and power quality of the electrical network through state estimation methods which are going to be widely used in modern systems. Observability is also important in making decisions for the planning of the network development by giving access to information about the grid operating conditions. Therefore it suggests how to focus the efforts to improve the electric power system performance according to the objectives established to reduce the impact of fossil fuels in the climate change. In sight of this, it can be concluded that the key to deal with climate change is a suitable coordination of such factors: the development of the network, the arrangement of flexibility resources and the communication systems improvement. During the Doctorate (Ph.D.), the author has worked on several research projects related to the topic of the evolution of the electric system. The project are listed in the Appendices. This thesis gathers the work done by underlining the importance of the three factors mentioned before in the context of the power system evolution. The developed applications will be presented as particular approaches that can be applied to a general power system and take place in one or more aspects of the ecological transition. In Chapter 1, the UN strategies to deal with climate change are introduced as well as the main consequences they led to and the new needs of the electric system are described. An introduction to regulation services and their purpose is given. In Chapter 2 the Italian context, as part of the European and Global plan to reduce emissions, is described. The main tools used by the Italian TSO to plan the network development are introduced and the study case of the network of Sicily is explained in the contest of the project ”Assessments of Battery Energy Storage Systems Potential in Improving the Working Condition of the Grid of Sicily”. As a continuation of this work, the method developed in the project ”Optimal Storage Allocation for Transmission Network Development Planning” is applied to the Sicilian network model and its possible contribution to network infrastructure planning is described. In Chapter 3 the impact that the installation of several RESs have on the grid stability is described. The consequent evolution process of the electricity market in order to cope with the increased need of regulation services is explained. In such context, pilot projects have been established by the TSO to encourage research of flexibility resources with reference to the projects concerning regulation service provision from loads and RESs. In Chapter 4, in project ”Flexibility Evaluation of an Aggregate of Thermal Load Units”, a definition of flexibility resources is given and a flexibility analysis of aggregates of thermal loads intended for domestic hot water heating, such as domestic electric water heaters or heat pumps, has been carried out during the research activity. A Monte Carlo approach is adopted for the methodology applied to the study case of Italy and Sicily. Chapter 5 describes and presents the results of the project ”Model Predictive Control for frequency regulation services provision” where the fast frequency reserve service is explored according to the related pilot project by using Model Predictive Control (MPC) based techniques applied on systems with RESs and Battery Energy Storage Systems (BESSs). Such service is meant to replace the beneficial effect of inertia from the traditional generating units which is progressively decreasing because of the implementation of RESs units in the power system. The decrease of inertia leads to more significant frequency variations after fault events that must be solved within extremely high speed actions, even faster than primary frequency regulation service. To complete the thesis, the Conclusions are presented together with some last comments. Finally, the publications produced during the Ph.D. and the projects to which contribution was given, collaborations and attended courses are listed, while references cited in this thesis end the dissertation

    Improvement of product development cycle time and cost by applying concurrent integrated design and assembly planning : executive summary

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    Sonca is a manufacturing operation producing torches and lanterns. In order for the Company to be competitive, one of the key factors is to introduce new products to market quicker and at a lower total product cost. A system titled "concurrent integrated design and assembly planning (CIDAP)" is developed to aid this process. It is identified that methods proposed by other researchers using different algorithms are not interactive enough and need too much space to store the representation of assembly sequences and time to process the assembly operations for a complex assembly. Besides, the commercially available systems and software are not integrated and are too universal. The data used is not compatible with the company's data file. The CIDAP framework focuses on concurrent and integration, in that the different processes in the whole product development cycle are carried out concurrently and are integrated. In the framework two techniques, namely KALG (Knowledge-based Assembly Liaison Graph) and KPN (Knowledge-based Petri Net) and four expert systems for selection of assembly system, feeder, gripper, and sensing technology are developed. Commercially available software such as Boothroyd and Dewhurst's DFMA (Design For Manufacture and Assembly) software, Rapid Prototyping and Quick Tooling are also applied in the framework. The frame work and the systems are applied to an actual case in designing a series of torches within the Company. Results show that the product development cycle time is improved by 25%, rework cost reduced by 20%, and final product cost reduced by 11 %. The Company has adopted the new framework. The developed systems and data files are not only applicable to the Company, but also to other small and medium size companies in Hong Kong and China with a similar scale and nature of operation

    Parallel and Distributed Computing

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    The 14 chapters presented in this book cover a wide variety of representative works ranging from hardware design to application development. Particularly, the topics that are addressed are programmable and reconfigurable devices and systems, dependability of GPUs (General Purpose Units), network topologies, cache coherence protocols, resource allocation, scheduling algorithms, peertopeer networks, largescale network simulation, and parallel routines and algorithms. In this way, the articles included in this book constitute an excellent reference for engineers and researchers who have particular interests in each of these topics in parallel and distributed computing

    COMPLEXITY OF PRODUCTS AND THEIR ASSEMBLY SYSTEMS

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    Many manufacturing and assembly challenges emerged due to the increased demand for products variety. Increased product variety caused by product evolution, customization and changes in their manufacturing systems. Variety allows manufacturers to satisfy a wide range of customer requirements, but it can also be a major contributing factor to complexity of assembly. Complexity is generally believed to be one of the main causes of the present challenges in manufacturing systems. Complex assembly systems are costly to implement, run, control and maintain. Complexity of assembly is an important characteristic worth exploring and modeling in the early design stage. Assessing complexity of a product is essential in being able to predict the cost and time needed to implement it. There is a relationship between the complexity of assembled products and the complexity of their assembly equipment and systems. The main objective of this research is to the complexity of assembly by: (1) Assessing the complexity of assembled products, (2) Assessing the complexity of their assembly systems, and (3) Derive the relationship between products and assembly systems complexities. First, a product complexity model has been developed by incorporating the information amount, content and diversity as well as the Design for Ease of Assembly (DFA) principles for assembled products. The new product complexity model assesses the total product assembly complexity using aggregated index for individual parts complexity. The new measure accounts for the different parts\u27 assembly attributes as well as their number and variety. Second, a structural classification coding (SCC) scheme has been extended to measure assembly systems complexity. It considers the inherent structural complexity of typical assembly equipment. The derived assembly system\u27s complexity accounts for the number, diversity and information content within each class of assembly system modules. Third, a dependency matrix which represents the interactions between parts assembly attributes and assembly system functions has been developed. It is used to predict the complexity of corresponding assembly equipment used for a certain product. A relationship between parts complexity and assembly equipment complexity has been developed using regression analysis. This research is applicable to the mechanical assembly of medium size products. An automobile piston, a domestic appliance drive, a car fan motor and a family of three-pin electric power plugs and their assembly systems were used as case studies to demonstrate the proposed approach and complexity assessment tools. The significance and importance of these research contributions is that: the developed complexity metrics can be used as decision support tools for products and systems designers to compare and rationalize various alternatives and select the design that meets the requirements while reducing potential assembly complexity and associated cost. Assessing complexity of assembly helps and guides designers in creating assembly-oriented product designs and following steps to reduce and manage sources of assembly complexity. On the other hand, reducing complexity of assembly helps lower assembly cost and time, improve productivity and quality, and increase profitability an

    Grid-Connected Renewable Energy Sources

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    The use of renewable energy sources (RESs) is a need of global society. This editorial, and its associated Special Issue “Grid-Connected Renewable Energy Sources”, offers a compilation of some of the recent advances in the analysis of current power systems that are composed after the high penetration of distributed generation (DG) with different RESs. The focus is on both new control configurations and on novel methodologies for the optimal placement and sizing of DG. The eleven accepted papers certainly provide a good contribution to control deployments and methodologies for the allocation and sizing of DG
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