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Numerical study on Rayleigh-Taylor effect on cylindrically converging Richtmyer-Meshkov instability

Science China(Physics,Mechanics & Astronomy) 2019年第12期62卷 68-77页

作者： ZhiGang Zhai Fu Zhang ZhangBo Zhou JuChun Ding Chih-yung Wen Department of Modern Mechanics University of Science and Technology of ChinaHefei 230026China Beijing Institute of Space Long March Vehicle Beijing 100076China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

Evolution of a two-dimensional air/SF6 single-mode interface is numerically investigated by an upwind CE/SE method under a cylindrically converging circumstance. The Rayleigh-Taylor effect caused by the flow deceleration on the phase inversion(RTPI)is highlighted. The RTPI was firstly observed in our previous experiment, but the related mechanism remains unclear. By isolating the three-dimensional effect, it is found here that the initial amplitude(a0), the azimuthal mode number(k0) and the re-shocking moment are the three major parameters which determine the RTPI occurrence. In the variable space of(k0, a0), a critical a0 for the RTPI occurrence is solved for each k0, and there exists a threshold value of k0 below which the RTPI will not occur no matter what a0 is. There exists a special k0 corresponding to the largest critical a0, and the reduction rule of critical a0 with k0 can be well described by an exponential decay function. The results show that the occurrence of the RTPI requires a small a0 which should be less than a critical value, a large k0 which should exceed a threshold, and a right impinging moment of the re-shock which should be later than the RTPI occurrence. Finally, the effects of the incident shock strength, the density ratio and the initial position of the interface on the threshold value of k0 and on the maximum critical a0 are examined. These new findings would facilitate the understanding of the converging Richtmyer-Meshkov instability and would be helpful for designing an optimal structure of the inertia confinement fusion capsule.

关键词： converging shock wave Rayleigh-Taylor effect Richtmyer-Meshkov instability

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Optimal duration of dual antiplatelet therapy after drugeluting stent implantation:Meta-analysis of randomized controlled trials

Optimal duration of dual antiplatelet therapy after drugelut...

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第十一届海峡两岸心血管科学研讨会、2017年全国心脑血管药理学术会议、中国卒中学会第一次新药研讨会

作者： Fei Yue Tsoi man-Fung Cheung Tommy Tsang Cheung Bernard man yung The University of hong Kong

Objective:After implantation of drug-eluting stents(DES),patients usually receive 6-12 months of dual antiplatelet therapy(DAPT).However,the optimal duration of DAPT is ***,we performed a meta-analysis of randomized controlled trials to assess the risks and benefits of different DAPT ***:We searched the literature using MEDLINE,Scopus,EMBASE,ISI Web of Science,

关键词： Optimal duration of dual antiplatelet therapy after drugeluting stent implantation:Meta-analysis of randomized controlled trials

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Adrenomedullin and diabetes

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World Journal of Diabetes 2014年第3期5卷 364-371页

作者： Hoi Kin Wong Fai Tang Tsang Tommy Cheung Bernard man yung Cheung Department of Pharmacology and Pharmacy University of Hong Kong Department of Physiology University of Hong Kong Department of Medicine University of Hong Kong Department of Medicine Queen Mary Hospital

Adrenomedullin(ADM) is a peptide hormone widely expressed in different tissues, especially in the vasculature. Apart from its vasodilatatory and hypotensive effect, it plays multiple roles in the regulation of hormonal secretion, glucose metabolism and inflammatory response. ADM regulates insulin balance and may participate in the development of diabetes. The plasma level of ADM is increased in people with diabetes, while in healthy individuals the plasma ADM concentration remains low. Plasma ADM levels are further increased in patients with diabetic complications. In type 1 diabetes, plasma ADM level is correlated with renal failure and retinopathy, while in type 2 diabetes its level is linked with a wider range of complications. The elevation of ADM level in diabetes may be due to hyperinsulinemia, oxidative stress and endothelial injury. At the same time, a rise in plasma ADM level can trigger the onset of diabetes. Strategies to reduce ADM level should be explored so as to reduce diabetic complications.

关键词： Adrenomedullin Diabetes Diabetic complications Hyperglycemia Therapeutics

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Semi-Probabilistic Evaluation of System Redundancy for Existing Offshore Structures

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China Ocean Engineering 1995年第1期10卷 1-8页

作者： Zhang, Shengkum Chen, Kaisheng Mu, yung

In this paper, a new definition of structure system redundancy is proposed in view of the various measures for structure redundancy. By introducing the terms of structure system failure at the mechanism level and equivalent reliability index, the safety for existing offshore platforms can be evaluated by the semi-probabilistic method presented in this paper. Some numerical examples are given and satisfactory results have been obtained.

关键词： residual strength semi-probabilistic method damaged structure redundancy reliability index critical value

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Flow management Mechanism in Software-Defined Network

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Computers, Materials & Continua 2022年第1期70卷 1437-1459页

作者： Eugene Tan yung-Wey Chong Mohammed F.R.Anbar National Advanced IPv6 Centre Universiti Sains MalaysiaUSMPenangMalaysia

Software-defined networking(SDN)is a paradigm shift in modern ***,centralised controller architecture in SDNimposed flow setup overhead issue as the control plane handles all flows regardless of size and *** frameworks strictly reduce control plane overhead and it does not focus on rule placement of the flows ***,existing frameworks do not focus on managing elephant flows like ***,the proposed mechanism will use the flow statistics gathering method such as random packet sampling to determine elephant flow and microflow via a predefined *** mechanism will ensure that the control plane works at an optimum workload because the controller only manages elephant flows via reactive routing and rule placement *** routing has reduced link bandwidth usage below the pre-defined ***,rule placement has increased average throughput and total transfer to 238%.Meanwhile,the data plane switches will be able to forward microflows via multipath wildcard routing without invoking controller in greater responding time by 85 ms faster in two Transmission Control Protocol(TCP)traffic and achieved 11%and 12%higher total transfer size and throughput ***,the controller’s workload reduced significantly to 48%in two TCP traffic.

关键词： Software-defined network controller flow management

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Probe-assisted NMR:Recent progress on the surface study of crystalline metal oxides with various terminated facets

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Magnetic Resonance Letters 2022年第1期2卷 9-16,I0002页

作者： yung-Kang Peng Shik-chi Edman Tsang Department of Chemistry City University of Hong KongKowloon TongHong Kong SAR0000China The Wolfson Catalysis Centre Department of ChemistryUniversity of OxfordOxfordOX13QRUK

The development of metal oxides with specific facet exposure for better catalytic performance in targeted applications has been ***,the understanding of surface structure-activity correlation is severely hindered by the current poor resolution of conventional surface characterization *** this mini-review,some of the latest research developments on the characterization of the surface structure and properties of faceted ZnO and TiO_(2)by probe-assisted nuclear magnetic resonance spectroscopy(NMR)are discussed.

关键词： Probe-assisted nuclear magnetic resonance Surface structure-property relationship ZnO TiO_(2)

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Fuzzy Logic Controller-based Synchronverter in Grid-connected Solar Power System with Adaptive Damping Factor

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Chinese Journal of Electrical Engineering 2021年第2期7卷 37-49页

作者： Kah yung Yap Chee Ming Beh Charles R.Sarimuthu Department of Electrical and Computer Systems Engineering(ECSE) School of EngineeringMonash University MalaysiaSubang Jaya 47500Malaysia

In recent years,renewable energy sources,specifically solar power systems,have developed rapidly owing to their technological maturity and cost ***,its grid integration deteriorates frequency stability because of insufficient rotating masses and inertial ***,a synchronverter,which is an inverter that mimics the operation of a synchronous generator,is crucial to interface solar power in a power *** stabilizes the power grid by emulating a virtual ***,a conventional proportional-integral(PI)-based synchronverter is not equipped with an adaptive damping factor(Dp)or a digitalized smart controller to manage fast-responding solar ***,a novel fuzzy logic controller(FLC)framework is proposed such that the synchronverter can operate in a grid-connected solar power *** this study,Dp is controlled in real time using an FLC to achieve balance between speed and stability for frequency error correction based on frequency *** of four case studies performed in Matlab/Simulink show that the proposed FLC-based synchronverter can stabilize the grid frequency by reducing the frequency deviation by at least 0.2 Hz(0.4%),as compared with the conventional PI-based synchronverter.

关键词： Fuzzy logic controller(FLC) synchronverter renewable energy system(RES) grid stability solar power system

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Mathematical Modeling of the Actual Infiltration Process for the Preparation of C/C Composites

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Engineering（科研） 2012年第12期4卷 921-927页

作者： Gui yung Chung Dong Geun Hwang Sung Soo hong Department of Chemical Engineering Hong-Ik University Seoul Korea

The mathematical modeling for the preparation of C/C composites from propane by F-CVI (Forced-flow Chemical Vapor Infiltration) was studied. The modeling for the actual processes including overturning the preform in the middle of the deposition process was carried out. Effects of the interval and the number of overturning processes on the time changes of porosity distribution were observed. The actual deposition process could be continued longer by overturning the preform. Furthermore, the total amount of deposition increased twice when several times of overturning were applied. It was confirmed that a low concentration and a slow reaction rate are necessary for a uniform infiltration even when the preform is overturned in the middle of the process.

关键词： Numerical Modeling C/C Composites CVI Overturning Propane

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Effects of common prebiotics on iron status and production of colonic short-chain fatty acids in anemic rats

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Food Science and Human Wellness 2021年第3期10卷 327-334页

作者： Fan Zhang Ken K.L.yung Chi KongYeung Division of Science and Technology BNU-HKBU United International CollegeZhuhaiGuangdongChina Department of Biology Hong Kong Baptist UniversityHong KongChina Animal Science Department California Polytechnic State UniversitySan Luis ObispoCaliforniaUSA

Prebiotics may enhance iron absorption,and one plausible mechanism involves the production of shortchain fatty acids(SCFA)in the colon by intestinal *** objectives of this study were to determine the effects of common commercially-available prebiotics including fructooligosaccharide(FOS),inulin,FOS-inulin mixture,galactooligosaccharide(GOS),and lactulose on the iron status of anemic rats,and to monitor changes in the production of colonic *** Sprague-Dawley rats receiving a lowiron diet(12μg Fe/g diet)were supplemented with or without prebiotics(5%m/V in drinking water)for 5 *** concentration in rats supplemented with GOS after 3 weeks(4.3 g/dL)was significantly higher than rats without supplementation(3.7 g/dL),while FOS also significantly increased hemoglobin concentration after 4 weeks(4.1 g/dL vs.3.7 g/dL).All other prebiotics showed no *** rats showed lower overall SCFA production in the colon than normal rats,and only FOS signifi cantly increased the production of the three main SCFA(acetic acid,propionic acid and isobutyric acid)identifi ed in anemic rats,with other prebiotics showing no noticeable *** results suggest that GOS and FOS may slightly improve iron status of anemic rats,but the role of SCFA in the colon is not clear.

关键词： Iron Non-digestible oligosaccharides Short-chain fatty acids Prebiotics Rat

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Adaptive Path Selection Scheme with Combining for Multiple Relaying Cooperative Communications Networks

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Journal of Electronic Science and Technology 2020年第1期18卷 83-92页

作者： yung-Fa Huang John Jenq Cing-Chia Lai Jyu-Wei Wang Department of Information and Communication Engineering Chaoyang University of TechnologyTaichung 41368 Department of Computer Science Montclair State UniversityMontclair 07043 Zyxel Communications Hsinchu 300 Department of Photonics and Communication Engineering Asia UniversityTaichung 41354

In future communications, cooperative communications with relay networks will be one of the most effective schemes to enlarge the coverage area and to boost the data rate. In the recent research results, the path selection, power allocation, and relay protocols on relay networks are the most important factors to improve the system performance. However, the channel quality of the direct transmission path and the relaying path has an influential effect on the performance of relay networks. Therefore, in this paper, we propose a best relaying path selection(BRPS) scheme to obtain the path diversity to improve the system capacity and data rate for cooperative networks(CNs). Simulation results show that the more the relay nodes are selected, the lower the bit error rate(BER) is. The proposed BRPS scheme obtains a high concession between both BER and system capacity for CNs.

关键词： Bit error rate(BER) cooperative communications diversity path selection relay networks

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