888 resultados para physically-based simulation


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许多基于物理机制的水文和作物模型需要日序列气象数据来驱动,CLIGEN是为WEPP等模型产生气候输入文件的天气发生器,可以产生10个日序列气象变量来满足这种需要,但是其在中国的适用性需要进行评估。研究的目标是利用黄土高原陕西长武1957~2001年的气象数据评估CLIGEN产生非降水要素(最高温度、最低温度、露点温度、太阳辐射和风速)的能力。结果表明,CLIGEN对最高温度、最低温度和露点温度的模拟效果较好,对太阳辐射和极端气候事件的模拟效果较差,对风速的模拟效果最差。相关性检验表明CLIGEN很好地保持了气象要素的季节性,这对模拟农业生产是非常重要的;但是没有保留气象要素逐日的自相关和互相关性,进而导致产生的温度变化不符合连续渐变的规律。

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作为空间环境效应之一的单粒子效应对航天器在轨道中的安全运行有着严重的威胁。为了清楚地认识这一效应的机制、机理,可以采用重离子加速器地面模拟的方法来研究这一效应。为此建立和完善了国内第一套基于重离子加速器的单粒子效应地面模拟实验装置,并在此装置上进行了Xe离子辐照IDT71256的单粒了效应实验。建立的基于兰州重离子加速器的单粒子效应地面模拟实验装置包括真空靶室系统和束流监测系统。实验用兰州重离子加速器提供的~(40)Ar完成了对整个装置的性能测试。结果表明:该装置能很好的满足单粒子效应研究的需求,真空靶室系统允许在不破坏真空的条件下更换器件,改变倾角,改变离子入射能量等。注量探测器实现了对弱束流非拦截式测量;能量探测器对Ar离子测量的偏差小于2%;束流均匀度探测器的位置分辨好于0.34mm。在这一实验装置上,用兰州重离子加速器提供的~(136)Xe对两片IDT71256的单粒子效应情况进行了模拟研究。结果发现:在两片器件中均观察到单粒子翻转和单粒子闭锁,而且两片器件均表现出明显的翻转不对称性,其中1→0的翻转约占总翻转数的90%。探讨了离子入射角、有效LET、和离子射程对翻转和闭锁截面的影响,发现除离子的有效LET以外,离子在器件中的射程也将在很大程度上影响器件的翻转和闭锁截面。

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“仿真是一种基于模型的活动”,任何仿真系统都不能离开模型的支持,如果每次开发新的系统都要重新建立模型,费时费力。随着仿真系统的日益复杂,导致仿真模型的结构也日趋复杂,模型管理亦日趋繁琐。因此,研究一种有效的模型管理方法,对于方便模型重用,提高开发效率有着重要的意义。实现对模型的有效管理,首先需要明确管理对象,然后把模型有条理的分类并且规范的描述出来,最后把模型存储在数据库中,供用户重用。论文首先在HLA联邦开发执行过程的基础上,分析和完善了HLA仿真建模体系,明确了HLA仿真中模型的层次;然后总结了现有的模型分类方法,从方便模型统一管理的角度,提出了一种可扩展的模型分类方法;引入了元数据和XML技术,实现了对模型的规范化描述;根据课题研究目的,提出了仿真模型管理系统的设计目标,并设计了系统的体系结构、功能模块和数据结构;最后,综合应用数据库、VC++等技术,实现了模型存储、模型的增、删、改、查以及用户管理等功能,实现了对于模型的统一管理。

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某些流程行业由于采用按配方进行分组加工的模式组织生产,在排产时存在多条路径调度优化的问题,应用一般的优化算法对于现场在线调度难以给出满意结果,而基于Agent的过程仿真在解决离散、非线性系统模拟方面有显著的优势,本文采用Agent的方法对生产过程建模,然后对方案组内的备选方案进行仿真,通过对比各方案的仿真结果找到最优的方案作为执行方案,为现场的优化排产提供决策支持。

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The purpose of this paper is to demonstrate the potential of the EXODUS evacuation model in building environments. The latest PC/workstation version of EXODUS is described and is also applied to a large hypothetical supermarket/restaurant complex measuring 50 m x 40 m. A range of scenarios is presented where population characteristics (such as size, individual travel speeds, and individual response times), and enclosure configuration characteristics (such as number of exits, size of exits, and opening times of exits) are varied. The results demonstrate a wide range of occupant behavior including overtaking, queuing, redirection, and conflict avoidance. Evacuation performance is measured by a number of model predicted parameters including individual exit flow rates, overall evacuation flow rates, total evacuation time, average evacuation time per occupant, average travel distance, and average wait time. The simulations highlight the profound impact that variations in individual travel speeds and occupant response times have in determining the overall evacuation performance. 1. Jin, T., and Yamada T., "Experimental Study of Human Behavior in Smoke Filled Corridors," Proceedings of The Second International Symposium on Fire Safety Science, 1988, pp. 511-519. 2. Galea, E.R., and Galparsoro, J.M.P., "EXODUS: An Evacuation Model for Mass Transport Vehicles," UK CAA Paper 93006 ISBN 086039 543X, CAA London, 1993. 3. Galea, E.R., and Galparsoro, J.M.P., "A Computer Based Simulation Model for the Prediction of Evacuation from Mass Transport Vehicles," Fire Safety Journal, Vol. 22, 1994, pp. 341-366. 4. Galea, E.R., Owen, M., and Lawrence, P., "Computer Modeling of Human Be havior in Aircraft Fire Accidents," to appear in the Proceedings of Combus tion Toxicology Symposium, CAMI, Oklahoma City, OK, 1995. 5. Kisko, T.M. and Francis, R.L., "EVACNET+: A Computer Program to Determine Optimal Building Evacuation Plans," Fire Safety Journal, Vol. 9, 1985, pp. 211-220. 6. Levin, B., "EXITT, A Simulation Model of Occupant Decisions and Actions in Residential Fires," Proceedings of The Second International Symposium on Fire Safety Science, 1988, pp. 561-570. 7. Fahy, R.F., "EXIT89: An Evacuation Model for High-Rise Buildings," Pro ceedings of The Third International Sym posium on Fire Safety Science, 1991, pp. 815-823. 8. Thompson, P.A., and Marchant, E.W., "A Computer Model for the Evacuation of Large Building Populations," Fire Safety Journal, Vol. 24, 1995, pp. 131-148. 9. Still, K., "New Computer System Can Predict Human Behavior Response to Building Fires," FIRE 84, 1993, pp. 40-41. 10. Ketchell, N., Cole, S.S., Webber, D.M., et.al., "The Egress Code for Human Move ment and Behavior in Emergency Evacu ations," Engineering for Crowd Safety (Smith, R.A., and Dickie, J.F., Eds.), Elsevier, 1993, pp. 361-370. 11. Takahashi, K., Tanaka, T. and Kose, S., "An Evacuation Model for Use in Fire Safety Design of Buildings," Proceedings of The Second International Symposium on Fire Safety Science, 1988, pp. 551- 560. 12. G2 Reference Manual, Version 3.0, Gensym Corporation, Cambridge, MA. 13. XVT Reference Manual, Version 3.0 XVT Software Inc., Boulder, CO. 14. Galea, E.R., "On the Field Modeling Approach to the Simulation of Enclosure Fires, Journal of Fire Protection Engineering, Vol. 1, No. 1, 1989, pp. 11-22. 15. Purser, D.A., "Toxicity Assessment of Combustion Products," SFPE Handbook of Fire Protection Engineering, National Fire Protection Association, Quincy, MA, pp. 1-200 - 1-245, 1988. 16. Hankin, B.D., and Wright, R.A., "Pas senger Flows in Subways," Operational Research Quarterly, Vol. 9, 1958, pp. 81-88. 17. HMSO, The Building Regulations 1991 - Approved Document B, section B 1 (1992 edition), HMSO publications, London, pp. 9-40. 18. Polus A., Schofer, J.L., and Ushpiz, A., "Pedestrian Flow and Level of Service," Journal of Transportation Engineering, Vol. 109, 1983, pp. 46-47. 19. Muir, H., Marrison, C., and Evans, A., "Aircraft Evacuations: the Effect of Passenger Motivation and Cabin Con figuration Adjacent to the Exit," CAA Paper 89019, ISBN 0 86039 406 9, 1989. 20. Muir, H., Private communication to appear as a CAA report, 1996.

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Evacuation analysis of passenger and commercial shipping can be undertaken using computer-based simulation tools such as maritimeEXODUS. These tools emulate human shipboard behaviour during emergency scenarios; however it is largely based around the behaviour of civilian passengers and fixtures and fittings of merchant vessels. If these tools and procedures are to be applied to naval vessels there is a clear requirement to understand the behaviour of well-trained naval personnel interacting with the fixtures and fittings that are exclusive to warships. Human factor trials using Royal Navy training facilities were recently undertaken to collect data to improve our understanding of the performance of naval personnel in warship environments. The trials were designed and conducted by staff from the Fire Safety Engineering Group (FSEG) of the University of Greenwich on behalf of the Sea Technology Group (STG), Defence Procurement Agency. The trials involved a selection of RN volunteers with sea-going experience in warships, operating and traversing structural components under different angles of heel. This paper describes the trials and some of the collected data.

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This study presents a fully coupled temperature–displacement finite element modelling of the injection stretch-blow moulding (ISBM) process of polyethylene terephthalate (PET) bottles using ABAQUS with a view to optimising the process conditions. A physically-based material model (Buckley model) was used to predict the mechanical behaviour of PET at temperatures slightly above its glass transition temperature. A model incorporating heat transfer between the stretch rod, the preform and the mould was built using axisymmetric solid elements. Extensive finite element analyses were carried out to predict the deformation, the distribution and history of strain and temperature during ISBM of a 20 g–330 ml bottle, which was made in an in situ test on a Sidel SB06 machine. Comparisons of numerical results with the measurements demonstrate that the model can satisfactorily model the sidewall thickness and material distributions. It is also shown that significant non-linear differentials exist in temperature and strain in both bottle thickness and length directions during the process. This justifies the employment of a volume approach to accurately predict the final mechanical properties of the bottles governed by the orientation and crystallinity which are highly temperature and strain dependent.

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The contribution of electron-phonon scattering and grain boundary scattering to the mid-IR (lambda = 3.392 mum) properties of An has been assessed by examining both bulk, single crystal samples-Au(1 1 1) and Au(1 1 0)-and thin film, polycrystalline An samples at 300 K and 100 K by means of surface plasmon polariton excitation. The investigation constitutes a stringent test for the in-vacuo Otto-configuration prism coupler used to perform the measurements, illustrating its strengths and limitations. Analysis of the optical response is guided by a physically based interpretation of the Drude model. Relative to the reference case of single crystal Au at 100 K (epsilon = - 568 + i17.5), raising the temperature to 300 K causes increased electron-phonon scattering that accounts for a reduction of similar to40 nm in the electron mean free path. Comparison of a polycrystalline sample to the reference case determines a mean free path due to grain boundary scattering of similar to 17 nm, corresponding to about half the mean grain size as determined from atomic force microscopy and indicating a high reflectance coefficient for the An grain boundaries. An analysis combining consideration of grain boundary scattering and the inclusion of a small percentage of voids in the polycrystalline film by means of an effective medium model indicates a value for the grain boundary reflection coefficient in the range 0.55-0.71. (C) 2005 Elsevier B.V. All rights reserved.

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This paper describes a collaborative practice, between an architect (the author) and a textile designer; its outcomes and the critical theoretical and feminist contexts from which the practice evolved and to which it still responds. The practice advocates the interweaving of more than the yarns, material and cultures on which it is physically based, but also the intertwining of theory and technology as a means to advance architectural practice. This is done in response to Ahrentzen’s charge to feminist scholars and practitioners to ‘embrace not only the abstract conceptual nature of much postmodernist theorizing but also that derived from the serious “hanging out”, looking at, listening to, scrutinising and theorizing lived experiences of the everyday’, in this instance the everyday practice of combining concrete and textiles.

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Low-velocity impact damage can drastically reduce the residual strength of a composite structure even when the damage is barely visible. The ability to computationally predict the extent of damage and compression-after-impact (CAI) strength of a composite structure can potentially lead to the exploration of a larger design space without incurring significant time and cost penalties. A high-fidelity three-dimensional composite damage model, to predict both low-velocity impact damage and CAI strength of composite laminates, has been developed and implemented as a user material subroutine in the commercial finite element package, ABAQUS/Explicit. The intralaminar damage model component accounts for physically-based tensile and compressive failure mechanisms, of the fibres and matrix, when subjected to a three-dimensional stress state. Cohesive behaviour was employed to model the interlaminar failure between plies with a bi-linear traction–separation law for capturing damage onset and subsequent damage evolution. The virtual tests, set up in ABAQUS/Explicit, were executed in three steps, one to capture the impact damage, the second to stabilize the specimen by imposing new boundary conditions required for compression testing, and the third to predict the CAI strength. The observed intralaminar damage features, delamination damage area as well as residual strength are discussed. It is shown that the predicted results for impact damage and CAI strength correlated well with experimental testing without the need of model calibration which is often required with other damage models.

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Tese de doutoramento, Geografia (Geografia Física), Universidade de Lisboa, Instituto de Geografia e Ordenamento do Território, 2014

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Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Meteorologia), Universidade de Lisboa, Faculdade de Ciências, 2015

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Although originally an academic and research product, the WS-PGRADE/gUSE framework is increasingly applied by commercial institutions too. Within the SCI-BUS project, several commercial gateways have been developed by various companies. WS-PGRADE/gUSE is also intensively used within another European research project, CloudSME (Cloud-based Simulation Platform for Manufacturing and Engineering). This chapter provides an overview and de-scribes in detail some commercial WS-PGRADE/gUSE based gateway implemen-tations. Two representative case studies from the SCI-BUS project, the Build and Test portal and the eDOX Archiver Gateway are introduced. An overview of WS-PGRADE/gUSE based gateways for running simulation applications in the cloud within the CloudSME project is also provided.

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Dissertação para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Vias de Comunicação e Transportes

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Energy systems worldwide are complex and challenging environments. Multi-agent based simulation platforms are increasing at a high rate, as they show to be a good option to study many issues related to these systems, as well as the involved players at act in this domain. In this scope the authors’ research group has developed a multi-agent system: MASCEM (Multi-Agent System for Competitive Electricity Markets), which simulates the electricity markets. MASCEM is integrated with ALBidS (Adaptive Learning Strategic Bidding System) that works as a decision support system for market players. The ALBidS system allows MASCEM market negotiating players to take the best possible advantages from the market context. However, it is still necessary to adequately optimize the player’s portfolio investment. For this purpose, this paper proposes a market portfolio optimization method, based on particle swarm optimization, which provides the best investment profile for a market player, considering the different markets the player is acting on in each moment, and depending on different contexts of negotiation, such as the peak and offpeak periods of the day, and the type of day (business day, weekend, holiday, etc.). The proposed approach is tested and validated using real electricity markets data from the Iberian operator – OMIE.