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The effect of downstream resistance on flow diverter treatment of a cerebral aneurysm at a bifurcation: A joint computational-experimental study

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Journal of Hydrodynamics 2018年第5期30卷 803-814页

作者： ANDerson C.O.Tsang Billy Y.S.Yiu Abraham Y.S.Tang w.C.Chung Gilberto k.k.Leung AlexANDer k.k.Poon Alfred C.H.Yu Simon S.M.Lai k.w.chow Department of Surgery Li Ka Shing Faculty of Medicine University of Hong Kong Department of Electrical and Computer Engineering University of Waterloo Department of Mechanical Engineering University of Hong Kong Department of Electrical and Electronic Engineering University of Hong Kong

Intracranial aneurysm can lead to hemorrhagic stroke upon rupture. Deployment of flow diverters can restrict the blood flow into aneurysm and mitigate the rupture risk. Computational fluid dynamics（CFD） and ultrasonography with pulse-wave and color Doppler ultrasound measurements were employed jointly to investigate the complex flow pattern in cerebral aneurysms, both before and after the deployment of flow diverters. Patient-specific configurations of both bifurcation and side-wall aneurysms were selected. The effect of downstream flow resistance was investigated by adjusting the volume flow rate and pressure at the outlet vessels computationally and experimentally. Velocity profiles in the aneurysm measured from ultrasonography showed good agreement with those from computer simulations. The discrepancy in velocity between the computational and experimental sets of data is less than 10%. The downstream resistance can alter the volume flux into a bifurcation aneurysm with a flow diverter deployed by 236%, while the corresponding value of a side-wall aneurysm is negligible. The vorticity of the aneurysmal flow was reduced by more than 80% in both cases after stenting. This study demonstrated that careful investigation of downstream flow resistance of a bifurcation aneurysm is essential to provide an accurate assessment of the aneurysmal flow dynamics after flow diverter deployment.

关键词： Intracranial aneurysms computational fluid dynamics (CFD) doppler ultrasound

Computational Fluid Dynamics Study of a Cardiovascular Disease:Thoracic Aortic Dissection

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Computational Fluid Dynamics Study of a Cardiovascular Disea...

The 16th Annual Conference of Hong kong Society of Theoretical and Applied Mechanics 2012、The 1st Mainland-Hong kong Youth Forum on Mechanics 2012、The 8th Shanghai-Hong kong Forum on Mechanics and Its Application 2012

作者： Y.S.Tang S.k.Lai Stephen w.k.Cheng k.w.chow Department of Mechanical Engineering the University of Hong Kong Department of Surgery the University of Hong Kong

An aortic dissection occurs when blood intrudes into the layers of the vascular wall, creating an artificial *** is a severe pathological situation,since the weakened vessel wall may expand and be subject to the risk of rupture and massive internal bleeding,resulting in high *** is believed that biomechanical factors would play a role in this disease condition. Endovascular repair has now become a frequently employed practice in the clinical treatment and management.A stent graft is deployed to cover the tears and restrict the flow from entering the artificial *** this study,computational fluid dynamics analysis is performed to study the hemodynamics of a dissected aorta(Fig.1).Simplified aortic geometries with realistic dimensions are *** velocity and pressure waveforms are prescribed at the inlet and outlet respectively. Blood flow configuration and biomechanical forces are ***-operation and post-operation conditions are also *** quantitative analysis can provide valuable information for clinicians to making therapeutic decision.

关键词： Computational Fluid Dynamics Study of a Cardiovascular Disease:Thoracic Aortic Dissection

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鱼类配合饵料生产中的质量控制

国外水产 1985年第1期 28-30页

作者： k.w.chow 梁亚全

配合饵料工业中的质量控制不仅包括每一饵料成分经过加工过程变成贮藏品时对质量标准进行的检验,而且包括在整个贮藏期间对各种成分的质量进行严密的监测.质量控制还包括:在混合过程中各种组分的均匀化以及使它们最终变成贮藏品形式的... 详细信息

配合饵料工业中的质量控制不仅包括每一饵料成分经过加工过程变成贮藏品时对质量标准进行的检验,而且包括在整个贮藏期间对各种成分的质量进行严密的监测.质量控制还包括:在混合过程中各种组分的均匀化以及使它们最终变成贮藏品形式的配合饵料.质量控制程序应包括原料、产品和贮藏三个方面.原料发展中国家的食品业比起发达国家来是

关键词：配合饵料最终产品鱼类水生动物质量控制质量管理

A Computational Fluid Dynamics Study on the Endovascular Treatment of Intracranial Aneurysms

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A Computational Fluid Dynamics Study on the Endovascular Tre...

Renormalization Group Theory and Its Application to Thermally-Induced Turbulence

作者： S.k.Lai Abraham Y.S.Tang k.M.Leung Gilberto k.k.Leung k.w.chow Department of Mechanical Engineering University of Hong Kong Division of Neurosurgery Department of SurgeryLi Ka Shing Faculty of MedicineUniversity of Hong KongQueen Mary Hospital

Intracranial aneurysm,a localized dilation of arterial blood vessels in the brain,is a severe cerebrovascular *** appropriate medical treatment,the rupture of intracranial aneurysms will result in high mortality rate due to excessive bleeding into the cavity surrounding the *** modern technological advances,endovascular stenting technique has now proven to be one effective technique in the clinical management of intracranial *** prime advantage of endovascular intervention over traditional open surgery is that the former procedure is less invasive,and thus a shorter recovery time will *** a mechanical point of view,a metallic stent,serving as a flow diverter,can be deployed to cover the entire aneurysm *** the blood flow inside the aneurysmal sac becomes stagnant,and thrombus formation is likely to *** is expected that a larger extent of thrombosis is capable of reducing the risk of growth and rupture of *** assess this clinical objective quantitatively,we construct a three-dimensional(3D) aneurysm model (see Fig.1) to investigate the blood flow patterns in stented and non-stented *** many idealized models with straight or curved parent blood vessel,the aneurysm of the current model is placed at the bifurcation point of cerebral arteries,a geometric configuration occurring frequently for many *** fluid dynamics techniques are applied to perform the blood flow *** inlet and outlet boundary conditions of this model are subjected to pulsatile velocity and pressure waveforms *** on the present study,the impact of hemodynamic and biomechanical factors on the aneurysm can be *** quantitative findings can also provide valuable information for clinical practitioners to understand and predict the hemodynamic behaviour in patient-specific cases.

关键词： A Computational Fluid Dynamics Study on the Endovascular Treatment of Intracranial Aneurysms

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Communications in Theoretical Physics 2004年第4期41卷 599-604页

作者： CAOYi-Gang w.k.chow DepartmentofBuildingServicesEngineering TheHongKongPolytechnicUniversityHongKongChina

Renormalization group theory applied to turbulence will be reviewed in this *** associated are used for analyzing thermally-induced *** properties such as effective viscosity and thermal diffusivity are derived.

关键词： renormalization group turbulence

Periodic waves of a Discrete Higher Order Nonlinear SchrSdinger Equation

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Communications in Theoretical Physics 2006年第6X期46卷 961-965页

作者： Robert Conte k.w. chow Service de physique de Pétat condensé (URA 2464) CEA-Saclay F-91191 Gif-sur-Yvette Cedex France Department of Mechanical Engineering University of Hong Kong Pokfulam Hong Kong China

The Hirota equation is a higher order extension of the nonlinear Schr6dinger equation by incorporating third order dispersion and one form of self steepening effect, New periodic waves for the discrete Hirota equation are given in terms of elliptic functions. The continuum limit converges to the analogous result for the continuous Hirota equation, while the long wave limit of these discrete periodic patterns reproduces the known resulr of the integrable Ablowitz-Ladik system.

关键词： discrete higher-order nonlinear SchrSdinger equation discrete Hirota equation elliptic function solutions

Numerical Study on Depinning Dynamics of Fluids Interacting with Disorder

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Communications in Theoretical Physics 2004年第4X期42卷 619-622页

作者： CAOYi-Gang w.k.chow DepartmentofBuildingServicesEngineering TheHongKongPolytechnicUniversityHongKongChina

we investigate the depinning of two-dimensional fluids interacting with quenched disorder, based on Langevin simulations. For weak disorder the fluids depin elastically and flow in an ordered state. A power-law scaling lit between velocity and driving force can be obtained for the onset of motion in the elastic regime. This is in good agreement with that of colloid, charge density wave, and superconducting vortex systems. with an increasing strength of the disorder, we find a sharp crossover to plastic de. Pinning, accompanied by a substantial increase in the depinning force. The scaling fit obtained in the elastic regime becomes invalid when plastic flow occurs. In the plastic regime, the fluids flow in channels and the hexatic order decays exponentially with drives.

关键词：流体力学数值模拟弹性去阻塞牛顿流体流体-固体界面分子动力学模拟

Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography

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Journal of Environmental Sciences 2016年第4期28卷 236-245页

作者： Huiping Huang Christopher w.k.chow Bo Jin School of Chemical Engineering The University of Adelaide School of Earth and Environmental Sciences The University of Adelaide Australian water Quality Centre SA Water Corporation

Understanding the complexity of dissolved organic matter（DOM）in stormwater has drawn a lot of interest,since DOM from stormwater causes not only environmental impacts,but also worsens downstream aquatic quality associated with water supply and *** study introduced and employed high-performance size exclusion chromatography（HPSEC）coupled with an ultraviolet–visible（UV–vis）diode array detector to assess changes in stormwater-associated DOM *** DOM was also analysed in relation to storm event characteristics,water quality and spectroscopic *** tools were used to determine the correlations within DOM and water quality *** showed that dissolved organic carbon（DOC）and UV absorbance at 254 nm（UV（254））as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events *** detector wavelengths（210and 254 nm）and their ratio（A（210）/A（254））were found to provide additional information on the physiochemical properties of stormwater-associated *** study indicated that A（210）/A（254） is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon *** study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters,and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences.

关键词： Stormwater Dissolved organic matter HPSEC

Hydrolyzed Al(Ⅲ) clusters:Speciation stability of nano-Al_(13)

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Journal of Environmental Sciences 2011年第5期23卷 705-710页

作者： Shuifeng wang Chihpin Huang Christopher w k. chow Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. E-mail: wgds@*** Institute of Environmental Engineering National Chiao Tung University Hsinchu Taiwan China Australian water Quality Centre SA Water Corporation 250 Victoria Square Adelaide SA 5000 South Australia

Pure nano-All3 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27Al-NMR, photo correlation spectroscopy （PCS）, and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al13. The quantity of Alb species analyzed by ferron assay in the initial aging period corresponded well with that of Al13, which has been confirmed in a dimension range of 1-2 nm by PCS. Al13 solutions at high concentrations （0.5-2.11 tool/L） were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al13 basis on the eTA1-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, All3 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90~C.

关键词： nano-All3 clusters inorganic polymer flocculant speciation stability