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Physical modeling based on hydrodynamic simulation for the design of InGaAs/InP double heterojunction bipolar transistors

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Chinese Physics B 2012年第5期21卷 669-674页

作者：葛霁刘洪刚苏永波曹玉雄金智 Key Laboratory of Microelectronics Device&Integrated Technology Institute of MicroelectronicsChinese Academy of Sciences

A physical model for scaling and optimizing InGaAs/InP double heterojunction bipolar transistors（DHBTs） based on hydrodynamic simulation is developed.The model is based on the hydrodynamic equation,which can accurately describe non-equilibrium conditions such as quasi-ballistic transport in the thin base and the velocity overshoot effect in the depleted collector.In addition,the model accounts for several physical effects such as bandgap narrowing,variable effective mass,and doping-dependent mobility at high fields.Good agreement between the measured and simulated values of cutoff frequency,f t,and maximum oscillation frequency,f max,are achieved for lateral and vertical device scalings.It is shown that the model in this paper is appropriate for downscaling and designing InGaAs/InP DHBTs.

关键词： InGaAs/InP double heterojunction bipolar transistors hydrodynamic simulation lateraland vertical scalable model

Exploring impact of street layout on urban flood risk of people and vehicles under extreme rainfall based on numerical experiments

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中国科学:技术科学英文版 2023年第9期66卷 2561-2574页

作者： MEI Chao LIU JiaHong SHI HongYuan WANG Hao WANG Jia DONG LiRong SONG TianXu ZHANG HaiJia State Key Laboratory of simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China Key Laboratory of River Basin Digital Twinning of Ministry of Water Resources(Preparation) Beijing 100038China Beijing Key Laboratory of Urban Water Cycle and Sponge City Technology Beijing Normal UniversityBeijing 100875China

Urban street layout is an important factor in the formation process, characteristics, and risk level of urban flooding;therefore, this study numerically investigates the impact of street layout on urban flood risk to people and vehicles. Four typical street-layout scenarios with areas of 3 km × 3 km are established based on a block-scale investigation. The layout types are regular grid,irregular grid, radial, and annular. Urban inundation models are then constructed for these typical street layouts based on the twodimensional(2D) hydrodynamic method. Two historic, extreme rainfall events, which occurred in Beijing on July 21, 2012 and in Zhengzhou on July 20, 2021, are used as rainstorm scenarios for urban inundation modelling. The flood risks to people and vehicles are then calculated. Results show that, for an extreme rainstorm on the block scale, the street layout impacts the spatial and temporal distributions of the inundation variables, which include the water depth, flow velocity, flood volume, and inundated area. Moreover, for the same extreme-rainfall scenario, the greatest differences in the total flood volume, maximum street-water depth, and maximum street-flow velocity caused by street-layout differences are 17.22%, 60.25%, and 61.50%, respectively.Among the four street layouts considered in this study, the annular street layout exhibits the lowest degrees of inundation and flood risk. For the same extreme-rainfall scenario, the proportions of high-risk road sections for adults and children in this layout are 58.89% and 62.28% smaller than those for the layout with the largest proportion of high-risk road sections, respectively;the proportions of high-risk road sections for the Honda Accord and Audi Q7 were 55.31% and 53.04% smaller, respectively. The findings of this study may aid scientific understanding and development of “flood-sensitive” block-scale street layouts and urban planning in the context of the changing environment.

关键词： urban inundation street layout urban form flood risk hydrodynamic simulation

Design,hydrodynamic Analysis,and Testing of a Bio-inspired Movable Bow Mechanism for the Hybrid-driven Underwater Glider

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Journal of Bionic Engineering 2023年第4期20卷 1493-1513页

作者： Yanhui Wang Yudong Guo Shaoqiong Yang Tongshuai Sun Xi Wang Huihui Zhou Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin UniversityTianjin300072China The Joint Laboratory of Ocean Observing and Detection Laoshan LaboratoryQingdao266237China

Hybrid-driven Underwater Glider(HUG)is a new type of underwater vehicle which integrates the functions of an Autonomous Underwater Glider(AUG)and an Autonomous Unmanned Vehicle(AUV).Although HUG has the characteristics of long endurance distance,its maneuverability still has room to be improved.This work introduces a new movement form of the neck of the underwater creature into HUG and proposes a parallel mechanism to adjust the attitude angle and displacement of the HUG’s bow,which can improve the steering maneuverability.Firstly,the influence of bow movement and rotation on the hydrodynamic force and flow field of the whole machine is analyzed by using the Computational Fluid Dynamics(CFD)method.The degree of freedom,attitude control range and movement amount of the Movable Bow Mechanism(MBM)are obtained,and then the design of MBM is completed based on these constraints.Secondly,the kinematic and dynamic models of MBM are established based on the closed vector method and the Lagrange equation,respectively,which are fully verified by comparing the results of simulation in Matlab and Adams software,then a Radial Basis Function(RBF)neural network adaptive sliding mode controller is designed to improve the dynamic response effect of the output parameters of MBM.Finally,a prototype of MBM is manufactured and assembled.The kinematic,dynamics model and controller are verified by experiments,which provides a basis for applying MBM in HUGs.

关键词： Underwater glider Movable bow mechanism hydrodynamic simulation Steering maneuverability

An AMR Capable Finite Element Diffusion Solver for ALE Hydrocodes

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Plasma Science and Technology 2015年第2期17卷 109-116页

作者： A.C.FISHER D.S.BAILEY T.B.KAISER D.C.EDER B.T.N.GUNNEY N.D.MASTERS A.E.KONIGES R.W.ANDERSON Lawrence Livermore National Laboratory Lawrence Berkeley National Laboratory

We present a novel method for the solution of the diffusion equation on a composite AMR mesh. This approach is suitable for including diffusion based physics modules to hydrocodes that support ALE and AMR capabilities. To illustrate, we proffer our implementations of diffu- sion based radiation transport and heat conduction in a hydrocode called ALE-AMR. Numerical experiments conducted with the diffusion solver and associated physics packages yield 2nd order convergence in the L2 norm.

关键词： hydrodynamic simulation heat conduction thermal radiation adaptive meshrefinement finite element method

Clinical value of intravesical prostatic protrusion in the evaluation and management of prostatic and other lower urinary tract diseases

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Asian Journal of Urology 2017年第3期4卷 174-180页

作者： Darab Mehraban Tehran University of Medical Sciences TehranIran

Intravesical prostatic protrusion(IPP)has emerged as a new prostatic morphometric parameter of significance to aid the clinicians in various aspects of managing the patients with some diseases of the lower urinary tract and the prostate.These include but may not be limited to its role in such conditions as:bladder outlet obstruction,trial without catheter,medical treatment effect,progression of lower urinary tract symptoms related to benign prostatic hypertrophy(LUTS/BPH),risk factor for bladder stone in BPH,overactive bladder,prostate carcinoma,and early urinary continence recovery after laparoscopic radical prostatectomy.In this review,I will try to summarize the different researchers’efforts on the potential practical application of this clinical tool.Technology is ever evolving to help us in the diagnosis and management of our patients.However,we as clinicians should contemplate their cost and possible suffering for the patient by wise and judicious utilization based on our clinical experience and tools.IPP seems to be one such promising clinical tool.

关键词： Intravesical prostatic protrusion Benign prostatic hypertrophy Diagnosis Treatment Prognosis Complications Prostatic adenocarcinoma hydrodynamic simulation Fluid structural interaction

Calculating buoy response for a wave energy converter-A comparison of two computational methods and experimental results

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Theoretical & Applied Mechanics Letters 2017年第3期7卷 164-168页

作者： Linnea Sjokvist Malin Goteman Magnus Rahm Rafael Waters Olle Svensson Erland Stromstedt Mats Leijon Division of Electricity Department of Engineering Science The Angstrom Laboratory Uppsala University Box 534 75121 Uppsala Sweden Center for Natural Disaster science (CNDS) Villavagen 16 SE-7S2 36 Uppsala Sweden

When designing a wave power plant, reliable and fast simulation tools are required. Computational fluid dynamics （CFD） software provides high accuracy but with a very high computational cost, and in operational, moderate sea states, linear potential flow theories may be sufficient to model the hydrodynamics. In this paper, a model is built in COMSOL Multiphysics to solve for the hydrodynamic parameters of a point-absorbing wave energy device. The results are compared with a linear model where the hydrodynamical parameters are computed using WAMIT, and to experimental results from the Lysekil research site. The agreement with experimental data is good for both numerical models.

关键词： hydrodynamic simulation Linear potential flow theory Experiments Wave energy Lysekil research site

NUMERICAL STUDY ON ENVIRONMENTAL IMPACTS OF THE THIRD SHANGHAI SEWERAGE PROJECT

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International Journal of Sediment Research 2002年第2期17卷 165-173页

作者： Cheng LIU1, Yun HE2, Joseph Hun-Wei LEE3 and Zhao-Yin WANG4 1 Dr., Asso. Prof., International Research and Training Center on Erosion and Sedimentation, Beijing, 100044, China & Anhui Institu Dr. Asso. Prof. International Research and Training Center on Erosion and Sedimentation Beijing 100044 China & Anhui Institute of Architecture Hefei 230022 China Lecturer Anhui Institute of Architecture Hefei 230022 China Prof. The University of Hong Kong Hong Kong China Prof. Dept. of Hydraulic Engineering Tsinghua University & International Research and Training Center on Erosion and Sedimentation Beijing 100084 China

Two-dimensional hydrodynamic simulation for the Yangtze Estuary is performed by using the Delft3D model adopting the shallow water equations and the finite volume method on a curvilinear body-fitted grid. The model is calibrated and validated using available tidal data and field measurements. The velocity vector fields, the tidal levels, the trajectories of drogues and the far field sewage dilution from the existing and proposed outfalls are studied for the spring/neap tide and the dry/wet season. The results show that the tidal currents and the runoff flow are able to dilute and disperse the sewage from the outfalls to the outer sea. The sewage dilution contours under various hydrodynamic conditions indicate that the discharged effluent at present have relatively minor impact on the water environment of the Yangtze Estuary; whereas the planned sewage plan would significantly deteriorate the water quality of the estuary in the absence of any treatment, especially during the neap tide of dry season. The drogue tracking shows that the effluent from the four outfalls will be transported downstream to the Hangzhou Bay. A study on the pollution due to the project and the self-purification capacity of Hangzhou Bay is proposed in addition to that of the Yangtze Estuary.

关键词： hydrodynamic simulation Outfall Far field sewage dilution Drogue tracking

A Combined Multi-Site and Multi-Device Decision Support System for Tidal In-Stream Energy

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A Combined Multi-Site and Multi-Device Decision Support Syst...