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In the present work, the derivation of two surrogate models (SMs) for modelling the flow around a propeller for small aircrafts is presented. Both methodologies use derived functions based on computations with the detailed propeller geometry. The computations were performed using k–ω shear stress transport for modelling turbulence. In the SMs, the modelling of the propeller was performed in a computational domain of disk-like geometry, where source terms were introduced in the momentum equations. In the first SM, the source terms were polynomial functions of swirl and thrust, mainly related to the propeller radius. In the second SM, regression analysis was used to correlate the source terms with the velocity distribution through the propeller. The proposed SMs achieved faster convergence, in relation to the detail model, by providing also results closer to the available operational data. The regression-based model was the most accurate and required less computational time for convergence. 相似文献
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目的:用全自动凯氏定氮仪测定蛋白质(以N计)不确定度进行分析与探讨。方法 :采用GB 5009.5-2016第一法凯氏定氮法测定蛋白质(以N计)含量,建立数学模型,通过对各个不确定度分量的计算合成,找出影响测量不确定度的因素,最终得出样品中蛋白质(以N计)含量的扩展不确定度与合成标准不确定度。结果:蛋白质(以N计)含量测定的扩展不确定度为(20.93±0.25)%,k=2。结论:采用JJF 1059.1-2012《测量不确定度评定与表示》,对不确定度进行评定,确保蛋白质(以N计)含量结果的准确性。 相似文献
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城市规划设计条件是关系房地产开发经营成本和收益的关键因素,本文从剖析房地产开发领域规划设计条件实施存在的问题和原因入手,着眼维护公开、公平、公正的房地产市场秩序,提出了解决问题的对策,对维护规划管理严肃性、促进房地产业健康有序发展具有积极意义。 相似文献
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就施工企业当前面临的风险 ,从订单风险、低价中标的效益风险、全面履行合同的责任风险、工程结算不及时的诉讼风险、提升企业经营层次的投资风险等方面进行了论证 ,以引起施工企业在市场竞争中如何赢得主动的思考。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(5):476-487
If an accident resulting in an emergency occurs at a nuclear facility, the emergency technical advisory body (ETAB) is asked to make technical advice to the national government for emergency response. In order for the ETAB to carry out its role, a significant amount of materials containing information on nuclear power plants is prepared in the ETAB. These materials are all paper copies and very voluminous. Therefore it is required that they should be computerized for more effective use. Further, methods should be developed which aid the ETAB to understand the status of the affected facility and to predict potential radioactivity release to the environment. To support the ETAB's activities in an emergency, the materials have been computerized as databases for more effective and quick use of them, and an expert system has been developed to quickly predict accident progression and environmental fission product release with the multivariate analysis method. The databases and the expert system have been unified to be a system of COSTA. The first phase of developing COSTA has been completed in FY1992. This paper describes the present status of development of COSTA. 相似文献
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AbstractThis article is meant as a gentle introduction to the topological terms that often play a decisive role in effective theories describing topological quantum effects in condensed matter systems. We first take up several prominent examples, mainly from the area of quantum magnetism and superfluids/superconductors. We then briefly discuss how these ideas are now finding incarnations in the studies of symmetry-protected topological phases, which are in a sense a generalization of the concept of topological insulators to a wider range of materials, including magnets and cold atoms. 相似文献
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基于分部求和(Summation By Parts)方法和同时逼近项(Simultaneous Approximation Terms)技术建立的有限差分方法,具有更高的精度和稳定性。同时在介质几何不连续、参数突变条件具有较大的优势。国内对SBP-SAT方法的相关研究目前较少,论文对该方法的研究背景,方法发展过程进行了介绍并基于SBP-SAT方法和弹性波动理论,结合初边值条件,推导出曲线网格条件下的弹性波动SBP-SAT离散方程。最后,通过数值模拟实现地震波传播过程,介绍该方法在地震数值模拟领域中的应用价值和前景。 相似文献
10.
This article is meant as a gentle introduction to the topological terms that often play a decisive role in effective theories describing topological quantum effects in condensed matter systems. We first take up several prominent examples, mainly from the area of quantum magnetism and superfluids/superconductors. We then briefly discuss how these ideas are now finding incarnations in the studies of symmetry-protected topological phases, which are in a sense a generalization of the concept of topological insulators to a wider range of materials, including magnets and cold atoms. 相似文献