37,927 research outputs found

    Logistics outsourcing and 3PL selection: A Case study in an automotive supply chain

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    Outsourcing logistics functions to third-party logistics (3PL) providers has been a source of competitive advantage for most companies. Companies cite greater flexibility, operational efficiency, improved customer service levels, and a better focus on their core businesses as part of the advantages of engaging the services of 3PL providers. There are few complete and structured methodologies for selecting a 3PL provider. This paper discusses how one such methodology, namely the Analytic Hierarchy Process (AHP), is used in an automotive supply chain for export parts to redesign the logistics operations and to select a global logistics service provider

    Application of optimization techniques to vehicle design: A review

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    The work that has been done in the last decade or so in the application of optimization techniques to vehicle design is discussed. Much of the work reviewed deals with the design of body or suspension (chassis) components for reduced weight. Also reviewed are studies dealing with system optimization problems for improved functional performance, such as ride or handling. In reviewing the work on the use of optimization techniques, one notes the transition from the rare mention of the methods in the 70's to an increased effort in the early 80's. Efficient and convenient optimization and analysis tools still need to be developed so that they can be regularly applied in the early design stage of the vehicle development cycle to be most effective. Based on the reported applications, an attempt is made to assess the potential for automotive application of optimization techniques. The major issue involved remains the creation of quantifiable means of analysis to be used in vehicle design. The conventional process of vehicle design still contains much experience-based input because it has not yet proven possible to quantify all important constraints. This restraint on the part of the analysis will continue to be a major limiting factor in application of optimization to vehicle design

    Performance of Sensitivity based NMPC Updates in Automotive Applications

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    In this work we consider a half car model which is subject to unknown but measurable disturbances. To control this system, we impose a combination of model predictive control without stabilizing terminal constraints or cost to generate a nominal solution and sensitivity updates to handle the disturbances. For this approach, stability of the resulting closed loop can be guaranteed using a relaxed Lyapunov argument on the nominal system and Lipschitz conditions on the open loop change of the optimal value function and the stage costs. For the considered example, the proposed approach is realtime applicable and corresponding results show significant performance improvements of the updated solution with respect to comfort and handling properties.Comment: 6 pages, 2 figure

    Economic optimization of component sizing for residential battery storage systems

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    Battery energy storage systems (BESS) coupled with rooftop-mounted residential photovoltaic (PV) generation, designated as PV-BESS, draw increasing attention and market penetration as more and more such systems become available. The manifold BESS deployed to date rely on a variety of different battery technologies, show a great variation of battery size, and power electronics dimensioning. However, given today's high investment costs of BESS, a well-matched design and adequate sizing of the storage systems are prerequisites to allow profitability for the end-user. The economic viability of a PV-BESS depends also on the battery operation, storage technology, and aging of the system. In this paper, a general method for comprehensive PV-BESS techno-economic analysis and optimization is presented and applied to the state-of-art PV-BESS to determine its optimal parameters. Using a linear optimization method, a cost-optimal sizing of the battery and power electronics is derived based on solar energy availability and local demand. At the same time, the power flow optimization reveals the best storage operation patterns considering a trade-off between energy purchase, feed-in remuneration, and battery aging. Using up to date technology-specific aging information and the investment cost of battery and inverter systems, three mature battery chemistries are compared; a lead-acid (PbA) system and two lithium-ion systems, one with lithium-iron-phosphate (LFP) and another with lithium-nickel-manganese-cobalt (NMC) cathode. The results show that different storage technology and component sizing provide the best economic performances, depending on the scenario of load demand and PV generation.Web of Science107art. no. 83

    A Nomographic Methodology for Use in Performance Trade-Off Studies of Parabolic Dish Solar Power Modules

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    A simple graphical method was developed to undertake technical design trade-off studies for individual parabolic dish models comprising a two-axis tracking parabolic dish with a cavity receiver and power conversion assembly at the focal point. The results of these technical studies are then used in performing the techno-economic analyses required for determining appropriate subsystem sizing. Selected graphs that characterize the performance of subsystems within the module were arranged in the form of a nomogram that would enable an investigator to carry out several design trade-off studies. Key performance parameters encompassed in the nomogram include receiver losses, intercept factor, engine rating, and engine efficiency. Design and operation parameters such as concentrator size, receiver type (open or windowed aperture), receiver aperture size, operating temperature of the receiver and engine, engine partial load characteristics, concentrator slope error, and the type of reflector surface, are also included in the graphical solution. Cost considerations are not included

    Effect of the matrix behavior on the damage of ethylene–propylene glass fiber reinforced composite subjected to high strain rate tension

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    This study investigates the origin of the strain rate effect on the mechanical behavior of a discontinuous glass fiber reinforced ethylene–propylene copolymer (EPC) matrix composite. This kind of composite materials are commonly used for automotive functional and structural applications. To this aim, a multi-scale experimental approach is developed. The deformation processes and the damage mechanisms observed at the microscopic scale are related to the material mechanical properties at the macroscopic scale. Tensile tests up to failure and specific interrupted tensile tests have been optimized and performed for high strain rates up to 200 s 1 to quantify the strain rate effect at different scales. High speed tensile tests have also been performed on the pure copolymer matrix. The threshold and the kinetic of damage have been quantified at both microscopic and macroscopic scales. Experimental results show that the composite behavior is strongly strain-rate dependent. The multi-scale analysis leads to the conclusion that the strain rate effect on the damage behavior of the EPC matrix composite is mainly due to the viscous behavior of the EPC matrix. SEM observations and analysis show that a localized deformation in the interface zone around fibers occurs at high strain rates and directly affects the visco-damage behavior. It is established that when the strain rate increases, the local deformation zone around the fibers behaves like a dissipation zone. Consequently, the damage initiation is delayed and the related kinetic is reduced with respect to the quasi-static loading case

    Shape optimization of three-dimensional stamped and solid automotive components

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    The shape optimization of realistic, 3-D automotive components is discussed. The integration of the major parts of the total process: modeling, mesh generation, finite element and sensitivity analysis, and optimization are stressed. Stamped components and solid components are treated separately. For stamped parts a highly automated capability was developed. The problem description is based upon a parameterized boundary design element concept for the definition of the geometry. Automatic triangulation and adaptive mesh refinement are used to provide an automated analysis capability which requires only boundary data and takes into account sensitivity of the solution accuracy to boundary shape. For solid components a general extension of the 2-D boundary design element concept has not been achieved. In this case, the parameterized surface shape is provided using a generic modeling concept based upon isoparametric mapping patches which also serves as the mesh generator. Emphasis is placed upon the coupling of optimization with a commercially available finite element program. To do this it is necessary to modularize the program architecture and obtain shape design sensitivities using the material derivative approach so that only boundary solution data is needed

    Effect of the matrix behavior on the damage of ethylene–propylene glass fiber reinforced composite subjected to high strain rate tension

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    This study investigates the origin of the strain rate effect on the mechanical behavior of a discontinuous glass fiber reinforced ethylene–propylene copolymer (EPC) matrix composite. This kind of composite materials are commonly used for automotive functional and structural applications. To this aim, a multi-scale experimental approach is developed. The deformation processes and the damage mechanisms observed at the microscopic scale are related to the material mechanical properties at the macroscopic scale. Tensile tests up to failure and specific interrupted tensile tests have been optimized and performed for high strain rates up to 200 s 1 to quantify the strain rate effect at different scales. High speed tensile tests have also been performed on the pure copolymer matrix. The threshold and the kinetic of damage have been quantified at both microscopic and macroscopic scales. Experimental results show that the composite behavior is strongly strain-rate dependent. The multi-scale analysis leads to the conclusion that the strain rate effect on the damage behavior of the EPC matrix composite is mainly due to the viscous behavior of the EPC matrix. SEM observations and analysis show that a localized deformation in the interface zone around fibers occurs at high strain rates and directly affects the visco-damage behavior. It is established that when the strain rate increases, the local deformation zone around the fibers behaves like a dissipation zone. Consequently, the damage initiation is delayed and the related kinetic is reduced with respect to the quasi-static loading case

    WiFi Hot Spot Service Business for the Automotive and Oil Industries: A Competitive Analysis

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    While you refuel for gas, why not refuel for information or upload vehicle data, using a cheap wireless technology as WiFi? This paper analyzes in extensive detail the user segmentation by vehicle usage, service offering, and full business models from WiFi hot spot services delivered to and from vehicles (private, professional, public) around gas stations. Are also analyzed the parties which play a role in such services: authorization, provisioning and delivery, with all the dependencies modelled by attributed digraphs. Account is made of WiFi base station technical capabilities and costs. Five year financial models (CAPEX, OPEX), and data pertain to two possible service suppliers: multi-service oil companies, and mobile service operators (or MVNOs). Model optimization on the return-on-investment (R.O.I.) is carried out for different deployment scenarios, geographical coverage assumptions, as well as tariff structures. Comparison is also being made with public GPRS and 3G data services, as precursors to HSPA/LTE, and the effect of WiFi roaming is analyzed. Regulatory implications, including those dealing with public safety, are addressed. Analysis shows that due to manpower costs and marketing costs, suitable R.O.I. will not be achieved unless externalities are accounted for and innovative tariff structures are introduced. Open issues and further research are outlined. Further work is currently carried out with automotive electronics sector, wireless systems providers, wireless terminals platform suppliers, and vehicle manufacturers. Future relevance of this work is also discussed for the emerging electrical reloading grids for electrical vehicles.WiFi, Fuel Stations, Business Models, Oil Company, Mobile Operator, WiFi Services, Regulations, Professional Vehicles

    Design oriented simulation of contact-friction instabilities in application to realistic brake assemblies

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    This paper presents advances in non-linear simulations for systems with contact-friction, with an application to brake squeal. A method is proposed to orient component structural modifications from brake assembly simulations in the frequency and time domains. A reduction method implementing explicitly component-wise degrees of freedom at the system level allows quick parametric analyses giving modification clues. The effect of the modification is then validated in the time domain where non-linearities can be fully considered. A reduction method adapted for models showing local non-linearities is purposely presented along with an optimization of a modified non linear Newmark scheme to make such computation possible for industrial models. The paper then illustrates the importance of structural effects in brake squeal, and suggests solutions
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