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An Exact Anisotropic Quark Star Model

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Chinese Journal of Astronomy and Astrophysics 2002年第3期2卷 248-259页

作者： M.K.Mak T.Harko DepartmentofPhysics TheHongKongUniversityofScienceandTechnologyClearWaterBayHongKong DepartmentofPhysics TheUniversityofHongKongPokfulamHongKong

We present an exact analytical solution of the gravitational field equations describing a static spherically symmetric anisotropic quark matter distribution. The radial pressure inside the star is assumed to obey a linear equation of state, while the tangential pressure is a complicated function of the radial coordinate. In order to obtain the general solution of the field equations a particular density profile inside the star is also assumed. The anisotropic pressure distribution leads to an increase in the maximum radius and mass of the quark star, which in the present model is around three solar masses.

关键词： Stars - quark: interior solution: anisotropy

Impact of window and air-conditioner operation behaviour on cooling load in high-rise residential buildings

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Building Simulation 2022年第11期15卷 1955-1975页

作者： Cong Yu Jia Du Wei Pan Department of Civil Engineering The University of Hong KongPokfulamHong KongChina

Space cooling is an important building energy end-use that was found in recent years to be significantly impacted by occupant ***,the majority of previous studies ignored the interplay between the operation of windows and air conditioners(ACs)on cooling load,particularly in building energy *** addition,studies on the analysis of cooling load characteristics regarding high-rise buildings are *** vertical effect of high-rise buildings on cooling load remains *** study thus aims to examine how window and AC operation behaviours impact the cooling load of high-rise buildings in an urban context demonstrated by a real-life typical 40-floor residential building in Hong *** study investigates window and AC operation behaviours jointly and examines the vertical effect on cooling load by using agent-based building energy modelling(BEM)techniques and initiating stochastic and diverse behaviour modes.A carefully designed questionnaire survey was conducted to help build behaviour modes and validate energy *** building energy models were established integrating meteorological parameters generated by the computational fluid dynamics(CFD)programme for ten typical floors and nine combinations of window and AC behaviour *** results show that comfort-based AC modes and schedule-based window modes yielded the lowest cooling *** the combined effect of AC and window uses,the maximum difference in cooling loads could be 26.8%.Behaviour modes and building height induce up to 32.4%differences in cooling ***,a deviation between the behaviour modes and height on the cooling load was *** findings will help develop a thorough energy model inferring occupants’window and AC behaviour modes along with the building height in high-rise residential *** findings indicate that the interaction impact of window and AC behaviour modes and height should be jointly considered in future high-rise buildin

关键词： occupant behaviour air conditioning natural ventilation high-rise residential building building energy use

Analysis of COVID-19 clusters involving vertical transmission in residential buildings in Hong Kong region

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Building Simulation 2023年第5期16卷 701-711页

作者： Pengcheng Zhao Department of Mechanical Engineering The University of Hong KongPokfulamHong KongChina

Multiple clusters of coronavirus disease 2019(COVID-19)in Hong Kong have involved vertical transmissions in residential buildings,wherein the flats of confirmed cases were often vertically *** on the buildings and cases associated with 19 such clusters were retrieved and compared with the corresponding data on the entirety of Hong Kong *** transmissions usually occurred in old high-rise buildings with small flat areas and low estate prices during *** addition,infection occurred frequently among the elderly and among upstairs neighbours of index ***-laden aerosols may have been transmitted between flats mostly via shared drainpipes,and the vertical distribution of the confirmed cases in a building varied by its drainage system *** buildings with their entire drainpipes installed indoors,both the upstairs and downstairs neighbours of the index case flats could be *** comparison,buildings with their drainage stacks installed outdoors had lower infection risks and demonstrated a clearer pattern of vertical transmission:most infected cases resided upstairs from the index case flats,indicating that the virus spread could be dominated by the stack *** study provides valuable data and analysis for developing epidemic control strategies for residential buildings.

关键词： drainage system high-rise building infection SARS-CoV-2 stack effect ventilation

Experimental investigation of the effect of flow turbulence and sediment transport patterns on the adsorption of cadmium ions onto sediment particles

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Journal of Environmental Sciences 2007年第6期19卷 696-703页

作者： HUANG Sui-liang NG Chiu-on GUO Qi-zhong Numerical Simulation Group for Water Environment College of Environmental Science and Engineering Nankai University Tianjin 300071 China Deptartment of Mechanical Engineering The University of Hong Kong Pokfulam Road Hong Kong Department of Civil and Environmental Engineering Rutgers State University of New Jersey 623 Bowser Road Piscataway NJ 08854 USA

The mechanism of flow turbulence, sediment supply conditions, and sediment transport patterns that affect the adsorption of cadmium ions onto sediment particles in natural waters are experimentally simulated and studied both in batch reactors and in a turbulence simulation tank. By changing the agitation conditions, the sediment transport in batch reactors can be categorized into bottom sediment-dominated sediment and suspended sediment-dominated sediment. It is found that the adsorption rate of bottom sediment is much less than that of suspended sediment, but the sediment transport pattern does not affect the final （equilibrium） concentration of dissolved cadmium. This result indicates that the parameters of an adsorption isotherm are the same regardless of the sediment transport pattern. In the turbulence simulation tank, the turbulence is generated by harmonic grid-stirred motions, and the turbulence intensity is quantified in terms of eddy diffusivity, which is equal to 9.84F （F is the harmonic vibration frequency） and is comparable to natural surface water conditions. When the turbulence intensity of flow is low and sediment particles stay as bottom sediment, the adsorption rate is significantly low, and the adsorption quantity compared with that of suspended sediment is negligible in the 6 h duration of the experiment. This result greatly favors the simplification of the numerical modeling of heavy metal pollutant transformation in natural rivers. When the turbulence intensity is high but bottom sediment persists, the rate and extent of descent of the dissolved cadmium concentration in the tank noticeably increase, and the time that is required to reach adsorption equilibrium also increases considerably due to the continuous exchange that occurs between the suspended sediment and the bottom sediment. A comparison of the results of the experiments in the batch reactor and those in the turbulence simulation tank reveals that the adsorption ability of the sedimen

关键词： water flow sediment transport pollutant interactions turbulence, adsorption

Asymptotic Results for Tail Probabilities of Sums of Dependent and Heavy-Tailed Random Variables

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Chinese Annals of Mathematics,Series B 2012年第4期33卷 557-568页

作者： Kam Chuen YUEN Chuancun YIN Department of Statistics and Actuarial Science The University of Hong Kong Pokfulam Road HongKong China. Corresponding author. School of Mathematical Sciences Qufu Normal University Qufu 273165 Shan- dong China

Abstract Let X1, X2,... be a sequence of dependent and heavy-tailed random variables with distributions F1, F2,.. on （-∞,∞）, and let T be a nonnegative integer-valued random variable independent of the sequence {Xk, k 〉 1}. In this framework, the asymptotic behavior of the tail probabilities of the quantities Sn = fi Xk and S（n） =∑ k=1 n 〉 1, and their randomized versions ST and S（τ） are studied. Some risk theory are presented. max Sk for 1〈k〈n applications to the

关键词： Asymptotic tail probability Copula Heavy-tailed distribution Partialsum Risk process

Application and reliability analysis of DPM system in site investigation of HK weathered granite

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Journal of University of Science and Technology Beijing 2005年第6期12卷 481-488页

作者： Zhuoying Tan Meifeng Cai Zhongqi Yue L.G. Tham C.F. Lee State Key Laboratory of High-Efficient Mining and Safety of Metal Mines （University of Science and Technology Beijing） Ministry of Education Beijing 100083 China Department of Civil Engineering University of Hong Kong Pokfulam Road Hong Kong China

A drilling process monitor （DPM） for ground characterization of weathered granite is presented. The monitor is portable and can be mounted on a hydraulic rotary drilling rig to record various drilling parameters in real time during normal subsurface investigation. The identification method for dominative and subsidiary interfaces has been established. The study reveals that the monitored drilling parameters are dependent on geotechnical materials and can be further applied to characterize ground interfaces. The t-test between manual logging and DPM logging has been carried out. The results show that the DPM has high accuracy in interfaces detection and well agreement with the manual logging. The findings show that the device and data analysis method are of potential application in subsurface drilling exploration in weathered granites. It also seems to have prospective uses in the determination of orebody boundary as well as in the detection of geohazards.

关键词： drilling process monitoring hydraulic rotary drill instrumented borehole drilling geotechnical engineering weathered granite

DYNAMIC RESPONSE OF PLATES DUE TO MOVING VEHICLES USING FINITE STRIP METHOD

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Applied Mathematics and Mechanics(English Edition) 2002年第5期23卷 507-513页

作者：程远胜张佑啟区达光 Faculty of Traffic Science and Engineering Huazhong University of Science and Technology Wuhan 430074 P R China Department of Civil Engineering The University of Hong KongPokfulam Road Hong Kong P R China

Dynamic response of beam-like structures to moving vehicles has been extensively studied. However, the study on dynamic response of plates to moving vehicles has so far received but scant attention. A plate-vehicle strip for simulating the interaction between a rectangular plate and moving vehicles was described. For the portion of strips that are in direct contact with the moving vehicles, the plate-vehicle strips were employed. Conventional plate finite strips were used to model the portion of strips that are not directly under the action of moving vehicles. In the analysis, each moving vehicle is idealized as a one-foot dynamic system with tire unsprung mass and sprund mass interconnected by a spring and a dashpot. The numerical results obtained from the proposed method agree well with available results.

关键词： plate moving vehicle dynamic response finite strip method

Three-stage aged refuse biofilter for the treatment of landfill leachate

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Journal of Environmental Sciences 2009年第1期21卷 70-75页

作者： LI Hongjiang ZHAO Youcai SHI Lei GU Yingying State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science and Engineering Tonggji University Shanghai 200092 China. Department of Civil Engineering The University of Hong Kong Pokfulam Road 999077 Hong Kong China

A field-scale aged refuse （AR） biofilter constructed in Shanghai Refuse Landfill, containing about 7000 m^3 aged refuse inside, was evaluated for its performance in the treatment of landfill leachate. This AR biofilter can be divided into three stages and can manage 50 m^3 landfill leachate per day. The physical, chemical, and biological characteristics of AR were analyzed for evaluating the AR biofilter as leachate treatment host. The results revealed that over 87.8%-96.2% of COD and 96.9%-99.4% of ammonia nitrogen were removed by the three-stage AR biofilter when the infiuent leachate COD and ammonia nitrogen concentration were in the range 5478-10842 mg/L and 811-1582 mg/L, respectively. The final effluent was inodorous and pale yellow with COD and ammonia nitrogen below 267-1020 mg/L and 6-45 mg/L, respectively. The three-stage AR biofilter had efficient nitrification but relative poor denitrification capacity with a total nitrogen （TN） removal of 58%-73%. The external temperature of AR biofilter did not influence the total ammonia nitrogen removal significantly. It was concluded that the scale-up AR biofilter can work very well and can be a promising technology for the treatment of landfill leachate.

关键词： aged refuse biofilter landfill leachate COD ammonia nitrogen

δ13C-δ18O Covariance:An Effective Indicator of Hydrological Closure for Lakes?

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Acta Geologica Sinica(English Edition) 2008年第5期82卷 975-981页

作者： CHEN Jing＇an WANG Fushun WAN Guojiang TANG Degui David Dian ZHANG HUNAG Ronggui LI Jian XIAO Tangfu State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang550002 Guizhou Department of Geography University of Hong Kong Pokfulam Road Hong Kong

The correlation between the δ^13C and δ^13C-δ^18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity. The influence of these factors on the δ^13C-δ^18O correlation may be different on different time scales. In this paper, two different-type lakes in southwestern China, Lake Erhai and Lake Chenghai, are selected to investigate the influence of climatic pattern on the δ^13C-δ^18O correlation and to evaluate the reliability of the δ^13C-δ^18O covariance as an indicator of hydrological closure. The results show that there exists good correlation between the δ^13C and δ^18O in Lake Erhai （overflowing open lake） and in Lake Chenghai （closed lake）. This suggests that the δ^13C-δ^18O covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant δ^13C and δ^18O as a result of climatic influence. The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of the δ^13C-δ^18O covariance in Lake Erhai and Lake Chenghai. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between δ^13C and δ^18O because of the buffering effect of high CO2 concentration on the δ^13C shift in hyper-alkaline lakes. We should be prudent when we use the covariance between δ^13C and δ^18O to judge the hydrological closure of lake.

关键词： carbonates δ^13C-δ^18O covariance hydrological closure climatic pattern