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Effect of cavity flow control on high-speed train pantograph and roof aerodynamic noise

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Railway Engineering Science 2020年第1期28卷 54-74页

作者： Hogun Kim Zhiwei Hu David thompson Aerodynamics and Flight Mechanics Research Group University of SouthamptonSouthampton SO171BJUK Institute of Sound and Vibration Research Dynamics Group University of SouthamptonSouthampton SO171BJUK

The pantograph and its recess on the train roof are major aerodynamic noise sources on high-speed *** this noise is particularly important because conventional noise barriers usually do not shield the ***,less attention has been paid to the pantograph recess compared with the *** this paper,the flow features and noise contribution of two types of noise reduction treatments rounded and chamfered edges are studied for a simplified high-speed train pantograph recess,which is represented as a rectangular cavity and numerically investigated at 1/10 *** delayed detached-eddy simulations are performed for the near-field turbulent flow simulation,and the Ffowcs Williams and Hawkings aeroacoustic analogy is used for far-field noise *** highly unsteady flow over the cavity is significantly reduced by the cavity edge modifications,and consequently,the noise radiated from the cavity is ***,effects of the rounded cavity edges on the flow and noise of the pantographs(one raised and one folded)are investigated by comparing the flow features and noise contributions from the cases with and without rounding of the cavity *** train running directions are also *** analysis shows that the highly unsteady flow within the cavity is reduced by rounding the cavity edges and a slightly lower flow speed occurs around the upper parts of the raised pantograph,whereas the flow velocity in the cavity is slightly increased by the *** pressure fluctuations occur on the folded pantograph and the lower parts of the raised pantograph,whereas weaker fluctuations are found on the panhead of the raised *** study shows that by rounding the cavity edges,a reduction in radiated noise at the side and the top receiver positions can be *** reductions in the other directions can also be found.

关键词： High-speed train Aeroacoustics Pantograph Pantograph recess Cavity flow Noise control

Using a fluvial archive to place extreme flood sediment(dis)connectivity dynamics in context of a longer-term record

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International Journal of Sediment Research 2022年第4期37卷 447-456页

作者： Kirstie Fryirs Chris thompson Damian Gore School of Natural Sciences Macquarie University Seqwater

The aim of this study was to establish the source and provenance of sediments deposited in a large floodplain sink during extreme floods in the Lockyer Creek catchment, Australia, in 2011 and 2013. We place the sediment source patterns in context of the longer-term record to determine whether coarsegrained sediment sources(i.e., very fine sand to very coarse sand) and the spatio-temporal pattern of(dis)connectivity have changed over time. We do this by matching the geochemical properties and age structure of a sediment profile located in a downstream floodplain sink to the elemental composition of source sediments. One hundred and fifty-seven sediment samples from 20 sites across the catchment are analysed using X-ray fluorescence(XRF) spectrometry to compare the elemental ratio composition of the downstream floodplain sink to its source materials. We use Optically Stimulated Luminescence(OSL)dating to determine the age structure of the sediments in the floodplain sink. The northern tributaries and parts of the Lockyer River trunk stream are the primary sources of coarse sediment. These areas are connected(coupled) to the lower trunk stream and floodplain sediment sink. Southern tributaries are largely disconnected(decoupled) and supply little sediment to the floodplain sediment sink. This pattern of sediment source contribution has remained similar over the last 6.8 ka at least. Sediment sources as observed in the 2011 flood have predominated over the mid-late Holocene whilst those in the 2013 flood are rare.

关键词： Sediment provenance Geomorphology Sediment source Sediment sink Lockyer Valley

Comparison between wave generation methods for numerical simulation of bimodal seas

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Water Science and Engineering 2016年第1期9卷 3-13页

作者： Daniel A.thompson Harshinie Karunarathna Dominic Reeve Energy & Environment Research Group Zienkiewicz Centre for Computational Engineering Swansea UniversityBay Campus

This paper describes an investigation of the generation of desired sea states in a numerical wave model. Bimodal sea states containing energetic swell components can be coastal hazards along coastlines exposed to large oceanic fetches. Investigating the effects of long-period bimodal seas requires large computational domains and increased running time to ensure the development of the desired sea state. Long computational runs can cause mass stability issues due to the Stokes drift and wave reflection, which in turn affect results through the variation of the water level. A numerical wave flume, NEWRANS, was used to investigate two wave generation methods： the wave paddle method, allowing for a smaller domain; and the internal mass source function method, providing an open boundary allowing reflected waves to leave the domain. The two wave generation methods were validated against experimental data by comparing the wave generation accuracy and the variance of mass in the model during simulations. Results show that the wave paddle method not only accurately generates the desired sea state but also provides a more stable simulation, in which mass fluctuation has less of an effect on the water depth during the long-duration simulations. As a result, it is suggested that the wave paddle method with active wave absorption is preferable to the internal wave maker option when investigating intermediate-depth long-period bimodal seas for long-duration simulations.

关键词： Wave modeling Wave generation RANS Swell wave Bimodal sea Long-period waves

A semi-analytical approach for calculating the equilibrium structure and radial breathing mode frequency of single-walled carbon nanotubes

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Acta Mechanica Sinica 2016年第6期32卷 1075-1087页

作者： J.Gong L.thompson G.Li Department of Mechanical Engineering Clemson University

A semi-analytical model for determining the equilibrium configuration and the radial breathing mode (RBM) frequency of single-wall carbon nanotubes (CNTs) is presented. By taking advantage of the symmetry characteristics, a CNT structure is represented by five independent variables. A line search optimization procedure is employed to determine the equilibrium values of these variables by minimizing the potential energy. With the equilibrium configuration obtained, the semi-analytical model enables an efficient calculation of the RBM frequency of the CNTs. The radius and radial breathing mode frequency results obtained from the semi-analytical approach are compared with those from molecular dynamics (MD) and ab initio calculations. The results demonstrate that the semi-analytical approach offers an efficient and accurate way to determine the equilibrium structure and radial breathing mode frequency of CNTs.

关键词： Carbon nanotubes Equilibrium structure Radial breathing mode frequency

An efficient method for unfolding kinetic pressure driven VISAR data

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High Power Laser Science and Engineering 2015年第3期3卷 50-58页

作者： M.Hess K.Peterson A.Harvey-thompson Sandia National Laboratories

Velocity Interferometer System for Any Reflector(VISAR) [Barker and Hollenbach, J. Appl. Phys. 43, 4669(1972)]is a well-known diagnostic that is employed on many shock physics and pulsed-power experiments. With the VISAR diagnostic, the velocity on the surface of any metal flyer can be found. For most experiments employing VISAR, either a kinetic pressure [Grady, Mech. Mater. 29, 181(1998)] or a magnetic pressure [Lemke et al., Intl J. Impact Eng. 38,480(2011)] drives the motion of the flyer. Moreover, reliable prediction of the time-dependent pressure is often a critical component to understanding the physics of these experiments. Although VISAR can provide a precise measurement of a flyer's surface velocity, the real challenge of this diagnostic implementation is using this velocity to unfold the timedependent pressure. The purpose of this paper is to elucidate a new method for quickly and reliably unfolding VISAR data.

关键词： laser driven blast wave pulsed-power VISAR

Resilience-Driven Road Network Retrofit Optimization Subject to Tropical Cyclones Induced Roadside Tree Blowdown

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International Journal of Disaster Risk Science 2021年第1期12卷 72-89页

作者： Fuyu Hu Saini Yang Russell G.thompson Theoretical Division Los Alamos National LaboratoryLos AlamosNM 87545USA Key Laboratory of Environmental Change and Natural Disaster Ministry of EducationBeijing Normal UniversityBeijing 100875China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Academy of Disaster Reduction and Emergency Management Ministry of Civil Affairs&Ministry of EducationBeijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China School of Engineering The University of MelbourneMelbourne 3052Australia

This article focuses on decision making for retrofit investment of road networks in order to alleviate severe consequences of roadside tree blowdown during tropical *** consequences include both the physical damage associated with roadside trees and the functional degradation associated with road networks.A trilevel,two-stage,and multiobjective stochastic mathematical model was developed to dispatch limited resources to retrofit the roadside trees of a road *** the model,a new metric was designed to evaluate the performance of a road network;resilience was considered from robustness and recovery efficiency of a road *** proposed model is at least a nondeterministic polynomialtime hardness(NP-hard)problem,which is unlikely to be solved by a polynomial time ***-optimal solutions for this problem can be obtained by a proposed trilevel *** random forest method was employed to transform the trilevel algorithm into a singlelevel algorithm in order to decrease the computation *** tree retrofit of a provincial highway network on Hainan Island,China was selected as a case area because it suffers severely from tropical cyclones every year,where there is an urgency to upgrade roadside trees against tropical *** found that roadside tree retrofit investment significantly alleviates the expected economic losses of roadside tree blowdown,at the same time that it promotes robustness and expected recovery efficiency of the road network.

关键词： Hainan Island Nondominated sorting genetic algorithm II(NSGA II) Random forest method Road network resilience Roadside tree retrofit Tropical cyclones

Esterified cellulose nanocrystals for reinforced epoxy nanocomposites

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Progress in Natural Science:Materials International 2022年第3期32卷 328-333页

作者： Lachlan thompson Mostafa Nikzad Igor Sbarski Aimin Yu Department of Chemistry and Biotechnology Swinburne University of Technology

The surface of cellulose nanocrystals(CNCs) was successfully modified with methacryloyl chloride to create esterified CNCs(M/CNCs). The modification was confirmed by Fourier Transfer Infra-Red Spectroscopy, X-ray Photoelectron Spectroscopy and Zeta potential measurement. With increased surface hydrophobicity, this modified CNC material exhibited improved compatibility with organic network. When used as a filler to be incorporated into a model epoxy resin, TEM results indicated that M/CNCs particles dispersed well in the epoxy network. It was observed that the inclusion of the M/CNCs had an impact upon the heat flow for the curing of the epoxy nanocomposite, leading to an improvement in the storage modulus when tested via dynamic mechanical analysis.

关键词： Cellulose nanocrystals Epoxy nanocomposites Surface modification

Experimental Analysis of Atypically Long Finned Oscillating Heat Pipe for Ventilation Waste Heat Recovery Application

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Journal of Thermal Science 2020年第3期29卷 667-675页

作者： MAHAJAN Govinda CHO Heejin SMITH Aaron thompson Scott M. Rheem Manufacturing MontgomeryAL 36109USA Department of Mechanical Engineering Mississippi State UniversityMsissippi StateMS 39762USA Department of Mechanical Engineering Auburn UniversityAubumnAL 36849USA

Oscillating heat pipes(OHP)which are constructed from a serpentine-arranged capillary tube possess a desirable aerodynamic form factor and provide for relatively high heat transfer rates via cyclic evaporation and condensation of an encapsulated working fluid with no internal wicking structure *** last two decades,OHP has been extensively investigated for its potential application in thermal management of various *** study presents an experimental investigation on the heat transfer performance of an atypically long finned *** heat transfer performance of the proposed OHP was analyzed and compared with a bare tube OHP with similar overall *** show that a unit row of finned OHP filled with n-pentane with fill ratio of 70%can recover up to(400±40)W of heat from a typical waste exhaust air *** additional pressure drop due to fins was estimated to be(6.8±2)Pa resulting in an increase of 1–2 W of fan power *** average heat recovery rate via finned OHP was found to be almost 80%more than bare tube OHP filled with same working fluid with same fill ratio.

关键词： oscillating heat pipe waste heat recovery ventilation

DNA Damage Response Inhibitor and Anti-PD-L1 Therapy for Prostate Cancer: Development of Predictive Biomarkers

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Engineering 2022年第5期8卷 12-15页

作者： Chuandong Geng Timothy C.thompson Department of Genitourinary Medical Oncology The University of Texas MD Anderson Cancer CenterHoustonTX 77030USA

*** Although androgen receptor biosynthesis and signaling inhibi-tors have significantly improved outcomes in patients with castra-tion-resistant prostate cancer(CRPC),there is still a dearth of effective treatment op... 详细信息

关键词： Cancer Therapy patients