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numerical and Experimental Study on Vibration and Noise of Embedded Rail System

Journal of Applied Mathematics and Physics 2017年第9期5卷 1629-1637页

作者： Fangyao Yeh Xiaoting Chang Yuchi Sung Bridge Engineering Division National Center for Research on Earthquake Engineering Taiwan Department of Civil Engineering National Taipei University of Technology Taiwan

The Kaohsiung light rail transit (LRT) system first introduced embedded rail system in Taiwan. However, domestic engineering consultants are still lacking in experience of analysis, design and construction of embedded rail systems. Noise and vibration of the mass rapid transit system is an important environmental issue in an urban environment. In order to understand the environmental impact of noise due to structural vibrations caused by a train running on the rail system, this paper establishes a numerical analysis procedure to perform a simulation. There are two fundamental parts to the numerical simulation: 1) vibration response due to a moving load and 2) radiation propagation of noise induced by structural vibration. The Kaohsiung LRT is used as a case study. The real embedded rail track system is modeled using ANSYS software with finite element analysis and the dynamic time history of the vibration response of the rail caused by a moving load is obtained. Secondly, the dynamic vibration response of the rail outputted by ANSYS is then imported into the software LMS *** to obtain the external radiation and sound field pressure distribution transferred from the rail to a specific monitoring point, based on the boundary element method. This paper also conducts field measurements of vibration velocity and sound pressure as a train passes. Both the experimental and analytical results for noise at specific points are compared and discussed. The proposed procedure promises to be suitable for practical vibration and noise analyses for rail systems.

关键词： Embedded Rail System Noise and Vibration Analysis Finite Element Method Boundary Element Method

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Seasonal prediction of Spring Dust Weather Frequency in Beijing

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Acta meteorologica Sinica 2011年第5期25卷 682-690页

作者：郎咸梅 International center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences

In this paper, seasonal prediction of spring dust weather frequency （DWF） in Beijing during 1982–2008 has been performed. First, correlation analyses are conducted to identify antecedent climate signals during last winter that are statistically significantly related to spring DWF in Beijing. Then, a seasonal prediction model of spring DWF in Beijing is established through multivariate linear regression analysis, in which the systematic error between the result of original prediction model and the observation, averaged over the last 10 years, is corrected. In addition, it is found that climate signals occurring synchronously with spring dust weather, particularly meridional wind at 850 hPa over western Mongolian Plateau, are also linked closely to spring DWF in Beijing. As such, statistical and dynamic prediction approaches should be combined to include these synchronous predictors into the prediction model in the real-time operational prediction, so as to further improve the prediction accuracy of spring DWF in Beijing, even over North China. However, realizing such a prediction idea in practice depends essentially on the ability of climate models in predicting key climate signals associated with spring DWF in Beijing.

关键词： spring dust weather frequency in Beijing prediction model systematic error climate model

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Landing noise of aircraft based on the fly-over measurements with a planar microphone array

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Chinese Journal of Acoustics 2002年第1期21卷 9-22页

作者： QIAO Weiyang (Aero-engine Department of Northwestern Polytechnical University Xi’an 710072) Ulf Michel (Turbulence research Department, German Aerospace center (DLR) Berlin 10623) Aero-engine Department of Northwestern Polytechnical University Xi'an 710072 Turbulence research Department German Aerospace Center DLR Berlin 10623

A large planar microphone array, which consists of 111 microphones, was successfully developed. The positions of 111 microphones in the array were determined by a random optimization procedure for the largest possible amplification and dynamic range. The beam pattern of planar array was obtained by numerical calculation. This planar array was applied to measure a two-dimensional mapping of the sound sources on landing aircraft. It is shown that important airframe noise sources can be identified. The spectra and directivity of any interested noise source can also be obtained by this measurement.

关键词： Landing noise of aircraft based on the fly-over measurements with a planar microphone array over

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Finite element method for one-dimensional rill erosion simulation on a curved slope

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International Soil and Water Conservation research 2015年第1期3卷 28-41页

作者： Lijuan Yan Tingwu Lei Jing Zhang Qingwen Zhang Liqin Qu Bureau of Comprehensive Development Ministry of Water ResourcesBeijing 100053PR China Key Laboratory of Modern Precision Agriculture Integration research College of Hydraulic and Civil EngineeringChina Agricultural UniversityBeijing 100083PR China Institute of Environment and Sustainable Development in Agriculture CAASBeijing 100081PR China International research and Training center on Erosion and Sedimentation Beijing 100048PR China

Rill erosion models are important to hillslope soil erosion prediction and to land use *** development of rill erosion models and their use has become increasingly of great *** purpose of this research was to develop mathematic models with computer simulation procedures to simulate and predict rill *** finite element method is known as an efficient tool in many other applications than in rill soil *** this study,the hydrodynamic and sediment continuity model equations for a rill erosion system were solved by the Galerkin finite element method and Visual Cþþ*** simulated results are compared with the data for spatially and temporally measured processes for rill erosion under different *** results indicate that the one-dimensional linear finite element method produced excellent predictions of rill erosion ***,this study supplies a tool for further development of a dynamic soil erosion prediction model.

关键词： Finite element method Simulation Rill erosion Dynamics Galerkin

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A comparative study of interface reconstruction algorithms in molten metal flow

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China Foundry 2013年第1期10卷 50-56页

作者： Young-Sim Choi Jun-Ho Hong Ho-Young Hwang e-Design center Korea Institute of Industrial TechnologyIncheon 406-840Korea

In the present research,two numerical schemes for improving the accuracy of the solution in the flow simulation of molten metal were *** method is the Piecewise Linear Interface Calculation(PLIC) method and the other is the Donor-Acceptor(D-A) *** verify the module of the interface reconstruction algorithms,simple problems were *** these validations,the accuracy and efficiency of these two methods were compared by simulating various real *** the numerical simulation of free surface flow,it is possible for the PLIC method to track very accurately the interface between *** PLIC method,however,has the weak point in that a lot of computational time is required,though it shows the more accurate interface *** Donor-Acceptor method has enough effectiveness in the macro-observation of a mold filling sequence though it shows inferior ***,for the problems that need the accurate solution,PLIC is more appropriate than *** accuracy may cause less efficiency in numerical *** method between D-A method and PLIC method should be chosen depends on the product.

关键词： interface reconstruction DA PLIC molten metal flow accuracy volume of fluid method

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Experimental and numerical Investigation on the Flow Characteristics around a Cross-Flow Wind Turbine

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Energy and Power Engineering 2016年第4期8卷 173-182页

作者： Takaaki Kono Akira Yamagishi Takahiro Kiwata Shigeo Kimura Nobuyoshi Komatsu research center for Sustainable Energy & Technology Kanazawa University Kanazawa Japan Division of Mechanical Science and Engineering Kanazawa University Kanazawa Japan

This study investigated the flow characteristics around a cross-flow wind turbine. A wind tunnel experiment (WTE) was performed to measure the flow characteristics past the wind turbine when operating at the optimal tip-speed ratio of λ = 0.4. In addition, computational fluid dynamics (CFD) simulations were performed for the flow field around the wind turbine that was operating at tip-speed ratios of λ = 0.1, 0.4, and 0.7. The CFD approach was validated against the WTE measurements. CFD results confirmed that with an increase in λ, the velocity deficit was generally increased in the leeward of the return side of the wind turbine, while it was generally decreased in the leeward of the drive side of the wind turbine. It was also confirmed that with an increase in λ, the turbulence kinetic energy was generally increased in the leeward of the return side of the wind turbine, while it generally decreased in the leeward of the drive side of the wind turbine.

关键词： Cross-Flow Wind Turbine Wind Tunnel Experiment CFD

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Preliminary Study on the Application of GPS Observations to a Mesoscale numerical Model

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Acta meteorologica Sinica 2005年第3期19卷 332-344页

作者：袁招洪丁金才陈敏 Shanghai Meteorological Bureau Nanjing University of Information Science and Technology Nanjing 210044 Shanghai Weather center Shanghai Pudong District Weather center

Based on observations from 11 stations inside the GPS (global positioningsystem) observation network, study is performed both on adjustment of the MM5 initial humidity fieldby means of, and nudging assimilations of, G-PW (short for GPS-sensed atmospheric precipitablewater) for a rainfall event happening in the Yangtze delta during June 23-24, 2002. Results showthat adjusting the initial moisture field through G-PW will enhance pronouncedly the ability of theinitial field to depict vapor distribution, thereby harnessing errors of atmospheric PW predictionat an early stage of model integration to improve more markedly the prediction of 6-h rainfall and,in contrast, nudging assimilations of G-PW show insignificant amelioration of model prediction, withless effect on the result by using a bigger nudging coefficient. On the whole, compared tosuccessive nudging assimilations of G-PW into the MM5, greater amelioration occurs in 6-h rainfallprediction from the G-PW adjusted initial moisture field. Also, evidence suggests that theimprovement of 6-h rainfall prediction with G-PW in correcting the initial humidity field isrealized mainly through the amelioration of the ability of grid-scale rainfall prediction while thenudging scheme achieves the improvement largely by bettering sub-grid scale rainfall prediction.

关键词： GPS (global positioning system) precipitable water assimilation mesoscale numerical model

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Mobility prediction Based Tracking of Moving Objects in Wireless Sensor Networks

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Chinese Journal of Electronics 2023年第4期32卷 793-805页

作者： TANG Chao XIA Yinqiu DOU Lihua School of Automation Beijing Institute of Technology Beijing Institute of Technology Chongqing Innovation center

This paper investigates the multi-sensor fused localization of moving targets in a wireless sensor network. Each ultra-wide band(UWB) sensor is assigned a stability weight according to its survival time prediction. The measurement accuracy of each sensor into the constraints of the weight distribution based on the interactive multi-model method, a double weight distribution algorithm that considers measurement accuracy and stability is proposed. Based on the double weight algorithm,the measurement information of each UWB sensor, the inertial measurement unit(IMU)-based state vector and the UWB-based state vector by federated Kalman filter are integrated to realize the correction of the IMU. Finally, several numerical simulations are performed to show that the proposed algorithm can effectively suppress the measurement dropout when tracking moving targets in a wireless sensor network, and it can also automatically adjust the weight of each sensor based on the measurement error covariance to improve the tracking accuracy.

关键词： Weight measurement Wireless communication Wireless sensor networks Measurement errors Target tracking Heuristic algorithms Measurement uncertainty

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Impact Factors on Fracturing Results of Coal Seams and Appropriate Countermeasures

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Journal of Energy and Power Engineering 2010年第6期4卷 16-26页

作者： X. Wang Y.H. Ding Y. Xu Y.Y. Duan Fracturing ＆ Acidizing Technical Service center Research Institute of Petroleum Exploration and Development China NationalPetroleum Corp. Langfang 065007 China

Hydraulic fracturing is one of the efficient means for the abundant low-permeability CBM （coal-bed methane） reserves in China, however, due to the unique features of coal seams （i.e., low temperature, strong adsorption and abnormal development of natural fracture systems） as compared with the conventional reservoirs, the fractures propagate is difficult and the risk of damage to coal seam itself and the hydraulic fractures would be extremely high in the course of fracturing. As a result, losses would be suffered on the post-frac production of CBM *** the mean of numerical simulation, in this paper, the main factors have impact on the post-frac results as well as the extent to which the impact is brought were researched, and the technical solutions for the improvement of the fracturing performance was put forwards.

关键词： Coal-seam fracturing hazard factors yield loss rate technical solutions.

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Measurement of the In-Plane Thermal Conductivity of Long Fiber Composites by Inverse Analysis

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Open Journal of Composite Materials 2017年第2期7卷 85-98页

作者： Bassam Assaf Vincent Sobotka Francois Trochu Applied research center on Polymer(CRASP) Department of Mechanical EngineeringEcole Polytechnique de MontrealStation“Centre-Ville”MontrealCanada

In the present work, inverse thermal analysis of heat conduction is carried out to estimate the in-plane thermal conductivity of composites. numerical simulations were performed to determine the optimal configuration of the heating system to ensure a unidirectional heat transfer in the composite sample. Composite plates made of unsaturated polyester resin and unidirectional glass fibers were fabricated by injection to validate the methodology. A heating and cooling cycle is applied at the bottom and top surfaces of the sample. The thermal conductivity can be deduced from transient temperature measurements given by thermocouples positioned at three chosen locations along the fibers direction. The inverse analysis algorithm is initiated by solving the direct problem defined by the one-dimensional transient heat conduction equation using a first estimate of thermal conductivity. The integral in time of the square distance between the measured and predicted values is the criterion minimized in the inverse analysis algorithm. Finally, the evolution of the in-plane composite thermal conductivity can be deduced from the experimental results by the rule of mixture.

关键词： Inverse Analysis In-Plane Thermal Conductivity Mold Design

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