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Effects of localized impurity on a dark soliton in a Bose-Einstein condensate with an external magnetic trap

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Chinese Physics B 2009年第7期18卷 2659-2666页

作者：李宏王东宁 School of Physics and electronic Science Hubei Normal University School of Mechanical and electronic engineering Huangshi Institute of Technology department of Electrical engineering The Hong Kong Polytechnic UniversityHung HomKowloon

The dynamics of a dark soliton has been investigated in a Bose Einstein condensate with an external magnetic trap, and the effects of localized impurity on the dynamics are discussed by the variational approach based on the renormalized integrals of motion. The reciprocal movement of the dark soliton is discussed by performing a standard linear analysis, and it is found that the effects of the localized impurity depend strictly on the positive or negative value of the impurity strength corresponding to the repulsive or attractive impurity. The numerical results confirm the theoretical analysis, and show that the effects also depend on the effective nonlinear coefficient and the harmonic frequency.

关键词： Bose-Einstein condensate dark soliton the variational approach impurity

Chemical characteristics of aerosols at coastal station in hong kong.Ⅱ. Environmental behavior of trace elements during the April 1995 to April 1996

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Journal of Environmental Sciences 2004年第2期16卷 212-221页

作者： K.S.Lam Z.L.Cheng S.C.Kot C.W.Tsang department of Civil and Structural engineering the Hong Kong Polytechnic UniversityResearch Center for Eco-Environmental Sciences Chinese Academy of SciencesDepartment of Mechanical Engineering The Hong Kong University of Science & Technology Clear Water BayDepartment of Applied Biology and Chemical Technology the Hong Kong Polytechnic University Hung Hom Hong Kong ChinaBeijing 100085 ChinaHong Kong ChinaHung Hom Hong Kong China

An one-year of sampling aerosol program was carried out during the period of April 1995 to April 1996 at coastal region, Cape D′Aguilar, in hong kong. The trace element composition of aerosol particles(TSP and PM 10 ) were measured and analyzed by using the Instrumental Neutron Activation Analysis(INAA) and Inductive Couple Plasma-Mass Spectrometry(ICP-MS) techniques. The results showed that the polluted elements such as: V, Zn, As, Pb, Cd, Sb, I, Se, Bi, with high enrichment factor(E.F) values, are derived from anthropogenic sources, while Sc, Al, Fe, Mn, Sm, La, Sr are less than 10 in E.F, these elements are related the crust and soil. The concentration of the trace elements are present seasonal variation i.e. summer low and winter high, whereas the V or noncrustal V(V *) present summer high and winter low, this phenomenon might be explained by local or regional oil combustion sources. Use three type of elemental ratio, e.g. La/Sm, Mn */V * and Bi/Al indicate that both TSP and PM 10 of La/Sm ratios are mainly related to soil and dust, Mn */V * are probably represent fossil combustion and Bi/Al are possibly associated with refuse incineration, ferromanganese alloys and aluminum production. The varimax rotation factor analysis for trace elements was performed. By means of the absolute principal component analysis(APCA) and multiple regression, the contribution of trace elements to possible sources and overall means of trace elements were estimated. The results showed that the present station is impacted by the anthropogenic species, although the quantities are different during the summertime and wintertime.

关键词： TSP PM 10 trace elements enhancement factor element ratios seasonal variation factor analysis

Dynamic performance of cable-stayed bridge tower with multi-stage pendulum mass damper under wind excitations——I:Theory

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Earthquake engineering and engineering Vibration 2007年第4期6卷 295-306页

作者：郭安薪徐幼麟李惠 School of Civil engineering Harbin Institute of Technology Harbin 150090 China department of Civil and Structural engineering The Hong Kong Polytechnic University Hung Hom Hong Kong China

In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.

关键词： multi-stage pendulum mass damper cable-stayed bridge single column tower wind-induced vibration

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Bidding Strategy for Coordinated Operation of Wind Power Plants and NGG-P2G Units in Electricity Market

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CSEE Journal of Power and Energy Systems 2022年第1期8卷 212-224页

作者： Xiang Gao Ka Wing Chan Shiwei Xia Xian Zhang Guibin Wang Shenzhen polytechnic ShenzhenChina and also with the department of Electrical engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina department of Electrical engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina School of Electrical and electronic engineering North China Electric Power UniversityBeijing 102206China School of Mechanical engineering and Automation Harbin Institute of TechnologyShenzhen 518055China College of Mechatronics and Control engineering Shenzhen UniversityShenzhen 518060China

The synergies between electricity and other energy resources could promote energy utilization efficiency in electricity *** this context,this paper proposes a bi-level stochastic optimization model for the joint operation of a coordinated wind power plant(WPP)and natural gas generating(NGG)-power to gas(P2G)suppliers participating in the day-ahead(DA)market and real-time(RT)market as well as providing real-time auxiliary *** coordinated supplier’s payoff is maximized in the upper level with consideration of the uncertainties of WPP output capacity and RT electricity price,while the social welfare of the grid is maximized in the lower *** results demonstrate the effectiveness of the proposed bidding model of the coordinated WPPs and NGG-P2G suppliers by examining its bidding behaviors and benefits with comparisons of four other bidding models.

关键词： Bi-level model bidding strategy WPP NGGP2G uncertainties

Heterogeneous MXene-based films with graded electrical conductivity towards highly efficient EMI shielding and electrothermal heating

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Nano Research 2024年第8期17卷 7264-7274页

作者： Yu Zhang Guangcheng Zhang Zhonglei Ma Jianbin Qin Xi Shen department of Aeronautical and Aviation engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Research Institute for Sports Science and Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

The increasing need for electromagnetic interference(EMI)shielding of electronics in cold environments such as those in aircraft,space exploration,and wearable heaters to avoid hazardous icing conditions or hypothermia requires the development of thin and lightweight EMI shielding materials preferably by absorbing rather than reflecting electromagnetic(EM)waves while also generating heat through energy-efficient electrothermal ***,it is challenging to achieve absorption-dominant EMI shielding and energy-efficient electrothermal heating simultaneously in a thin and lightweight ***,we develop a heterogeneous composite film comprising a porous multi-walled carbon nanotubes(MWCNTs)/bacterial cellulose(BC)film and an aligned MXene/Ag nanowires(NWs)backing via a sequential vacuum filtration *** porous film contains random conductive networks of MWCNTs with moderate conductivity while the aligned MXene sheets atop Ag NWs network affords high conductivity in the backing,giving rise to graded electrical conductivity for absorption-dominant EMI *** increasing Ag NW coverage leads to significantly increased electrical conductivity without increasing the EM wave reflection as well as the density and thickness of the film,yielding excellent specific EMI shielding effectiveness(>8500 dB/(g·cm^(2))),low driving voltage for energy-efficient electrothermal heating(163℃at 2.5 V),and fast response time(60 s)at a low areal density of 0.015 mg/cm^(2).Combining EMI shielding and electrothermal heating,the heterogeneous film developed here are promising contenders for the protection of electronic equipment in low-temperature environment.

关键词： heterogenous composite film MXene electromagnetic interference(EMI)shielding thermal management

Review of analytical methods for stress and deformation analysis of buried water pipes considering pipe-soil interaction

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Underground Space 2023年第6期13卷 205-227页

作者： Yingxu Huo Sherif Mohsen Mohamed Hassan Gomaa Tarek Zayed Mohamed Meguid department of Civil and Environmental engineering The Hong Kong Polytechnic UniversityHung HomHong Kong 999077China department of Building and Real Estate The Hong Kong Polytechnic UniversityHung HomHong Kong 999077China Structural engineering department Faculty of EngineeringMansoura UniversityMansoura 35516Egypt department of Civil engineering McGill UniversityMontrealQuebec H3A 0G4Canada

Buried water pipelines are vulnerable to fail or break due to excessive loading or ground *** evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil interactions(PSI).Analytical methods are important approaches to studying ***,a systematic and thorough literature review to analyze the existing research trends,technological achievements and future research opportunities is not *** work investigates analytical methods that analyze the stress and deformation of pipes in terms of cross-sectional,transverse and longitudinal PSI ***,scientometric analysis is performed to acquire relevant research works from online databases and analyze the existing data of influential authors,productive research sources and frequent key word occurrence in the fields of ***,a qualitative discussion is performed in the three categories of PSI:(1)cross-sectional,including ovalization and circumferential behaviours;(2)transverse,including seismic fault crossing,weak soil zones,ground settlement and pipe uplift;and(3)***,six research opportunities are discussed,including the role of friction in cross-sectional deformation,combined effects of bending and compression,choice of soil reaction models and calibration of key parameters,effect of pipe flaws,soil spatial variability and behaviours of curved *** study helps beginners familiarize themselves with PSI analytical methods and provides experienced researchers with ideas for future research directions.

关键词： Pipeline Analytical methods Pipe-soil interactions Seismic fault Settlement Uplift Buckling Tunnelling

Condition assessment of structures under unknown support excitation

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Earthquake engineering and engineering Vibration 2009年第1期8卷 103-114页

作者： Zhang Kun S. S. Law Duan Zhongdong School of Civil engineering Harbin Institute of Technology Harbin 150090 China Civil and Structural engineering department Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong China

A new method is proposed to assess the condition of structures under unknown support excitation by simultaneously detecting local damage and identifying the support excitation from several structural dynamic responses. The support excitation acting on a structure is modeled by orthogonal polynomial approximations, and the sensitivities of structural dynamic response with respect to its physical parameters and orthogonal coefficients are derived. The identification equation is based on Taylor＇s first order approximation, and is solved with the damped least-squares method in an iterative procedure. A fifteen-story shear building model and a five-story three-dimensional steel frame structure are studied to validate the proposed method. Numerical simulations with noisy measured accelerations show that the proposed method can accurately detect local damage and identify unknown support excitation from only several responses of the structure. This method provides a new approach for detecting structural damage and updating models with unknown input and incomplete measured output information.

关键词： condition assessment damage detection support excitation identification dynamic response sensitivity

Direct synthesis of L10-FePt nanopartides from single-source bimetallic complex and their electrocatalytic applications in oxygen reduction and hydrogen evolution reactions

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Nano Research 2019年第12期12卷 2954-2959页

作者： Zhengong Meng Fei Xiao Zhuoxun Wei Xuyun Guo Ye Zhu Yurong Liu Guijun Li Zhen-Qiang Yu Minhua Shao Wai-Yeung Wong College of Chemistry and Environmental engineering and Institute of Low-dimensional Materials Genome Initiative Shenzhen UniversityShenzhen 518060China department of Chemical and Biological engineering Hong Kong University of Science and TechnologyClear Water BayKowloon 999077Hong KongChina department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityHung HomHong KongChina department of Applied Physics The Hong Kong Polytechnic UniversityHung HomHong Kong China State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomHong KongChina The hong kong polytechnic University Shenzhen Research Institute Shenzhen 518057China

L10-FePt nan oparticles(NPs)with high chemical ordering represent effective electrocatalysts to reduce the cost and enhance theircatalytic performanee in fuel cells.A molecular strategy of preparing highly ordered FePt NPs was used by direct pyrolysis of a Fe,Pt-containing bimetallic *** resultant L10-FePt NPs had very high crystallinity as reflected by the obvious diffractionpatterns,clear lattice fringes and characteristic X-ray diffraction peaks,***,the strong ferromagnetism with room temperaturecoercivity of 27 kOe further confirmed the face-centered tetrag on al(fet)phase in good agreement with the ordered nano *** NPs can be used as electrocatalysts to catalyze oxygen reduction reaction(ORR)in an O2·saturated 0.1 M HClO4 solution andhydrogen evolution reaction(HER)in the 0.5 M H2SO4 electrolyte with much better performance than commercial Pt/C,and showedquite high stability after 10,000 *** strategy utilizing orga no metallic precursors to prepare metal alloy NPs was dem on strated tobe a reliable approach for improving the catalytic efficiency in fuel cells.

关键词： bimetallic complex single-source precursor FePt nanoparticle oxygen reduction reaction hydrogen evolution reaction

Degradation of methotrexate by UV/peroxymonosulfate:Kinetics,effect of operational parameters and mechanism

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Chinese Journal of Chemical engineering 2020年第10期28卷 2658-2667页

作者： Muhammad Imran Kanjal Majid Muneer Amal Abdelhaleem Wei Chu department of Civil and Environmental engineering The Hong Kong Polytechnic UniversityHung HomKowloon 999077Hong KongChina department of Chemistry Government College UniversityFaisalabad 38000Pakistan

Methotrexate(MTX)is one of the most consumed anti-cancer drugs in the pharmaceutical market around the *** widespread occurrence of MTX in aquatic environment through hospital effluent has attracted increasing concern due to its potential to induce water *** the present study,the degradation of MTX in aqueous medium was investigated by UV-activated peroxymonosulfate(PMS).A significant improvement in degradation rate by increasing UV intensity and PMS concentration while the decrease in degradation efficiency with the increase of solution p H and initial concentration of MTX was *** proposed UV/PMS process could achieve more than 90%MTX degradation in 30 min with a good mineralization degree(65%).A pseudofirst order kinetic model was employed and successfully predicted the degradation of *** effect of other operational parameters such as the initial concentration of the targeted compound,dosage of oxidant(PMS),solution p H and UV intensity on the degradation rate were *** the last,the main transform intermediates were identified using LC–MS and possible degradation pathways were *** results show that UV/PMS can be used as an efficient technology to treat pharmaceuticals such as methotrexate containing water and wastewater.

关键词： Peroxymonosulfate UV radiation Advanced oxidation process Methotrexate