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Intraseasonal Variation of Visibility in Hong Kong

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Advances in Atmospheric Sciences 2017年第1期34卷 26-38页

作者： Wen ZHOU Richard c.y.LI Eric c.H.cHOW Guy carpenter Asia-Pacific climate Impact center School of Energy and EnvironmentCity University of Hong KongHong KongChina city University of Hong Kong Shenzhen Research Institute Shenzhen518057China

Visibility is one of the parameters for indicating air pollution. In this study, visibility variation in Hong Kong during summer and winter is investigated. Visibility in Hong Kong has clear intraseasonai variation. Examination of different environmental parameters suggests that the intraseasonal component dominates the overall circulation anomalies in both summer and winter. Associated with the intraseasonal variation of environmental parameters, obvious variation in visibility impair- ment is found in both summer and winter. In summer, local visibility and air quality are found to be significantly affected by the （MJO） and the 10-30-day intraseasonal oscillation （ISO） through modulation of associated atmospheric circulations. In winter, the modulation effects appear to be weaker due to the southward shift of the associated convection. The results in this study highlight the importance of the ISO in contributing to the overall variation in visibility in Hong Kong, and provide useful implications for the development of possible mitigation strategies associated with visibility impairment and air pollution in Hong Kong.

关键词： visibility intraseasonal oscillation air quality Hong Kong

Mechanistic study of vacuum UV catalytic oxidation for toluene degradation over ceO_(2) nanorods

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Green Energy & Environment 2022年第3期7卷 533-544页

作者： Muyan Wu yingguang Zhang Haibao Huang Dennis y.c.Leung Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou510275China

The present study specifically investigates vacuum ultraviolet (VUV) catalytic oxidation for toluene degradation over ceO_(2) *** effects of ultraviolet photocatalytic oxidation (UV-PcO) and ozone catalytic oxidation (OZcO) were manifested in the results of toluene removal and cOx generation,while the combination of UV-PcO andOZcO (UV-OZcO) did not lead to improvement of *** the processes contribute to ozone decomposition,but no obvious synergetic effects of the different processes can be *** analysis results indicated that more toluene was oxidized into by-products,such as benzyl alcohol and benzaldehyde,by UV-OZcO rather than forming *** hydroxyl radical (·OH) and superoxide radical (·O_(2)^(-)) were found in all the processes of the VUV-PcO-OZcO system(combination of VUV photolysis,UV-PcO,OZcO and UV-OZcO processes).In the UV-OZcO process,the formation of hydroxyl radical was promoted,while that of superoxide radical was impeded,resulting in lower mineralization level of *** mechanistic study of toluene degradation over ceO_(2) nanorods in the VUV-PcO-OZcO system revealed that with the formation of·O_(2)^(-)and·OH,toluene is first oxidized to intermediates,followed by further ring–opening reaction and,finally,degradation into cO_(2) and H_(2)***_(2) nanorods function as both ozonation catalyst and photocatalyst,and the redox pair of ce^(3+)and ce^(4+)are interconvertible and can keep a balance.

关键词： toluene catalytic vacuum

Uncertainty propagation analysis by an extended sparse grid technique

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Frontiers of Mechanical Engineering 2019年第1期14卷 33-46页

作者： X.y.JIA c.JIANG c.M.FU B.y.NI c.S.WANG M.H.PING State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China Key Laboratory of Electronic Equipment Structure Design ofMinistry of Education School of Electro-Mechanical EngineeringXidian UniversityXi'an 710071China

In this paper,an uncertainty propagation analysis method is developed based on an extended sparse grid technique and maximum entropy principle,aiming at improving the solving accuracy of the high-order moments and hence the fitting accuracy of the probability density function(PDF)of the system *** proposed method incorporates the extended Gauss integration into the uncertainty propagation ***,assisted by the Rosenblatt transformation,the various types of extended integration points are transformed into the extended Gauss-Hermite integration points,which makes the method suitable for any type of continuous ***,within the sparse grid numerical integration framework,the statistical moments of the system response are obtained based on the transformed ***,based on the maximum entropy principle,the obtained first four-order statistical moments are used to fit the PDF of the system ***,three numerical examples are investigated to demonstrate the effectiveness of the proposed method,which includes two mathematical problems with explicit expressions and an engineering application with a black-box model.

关键词： uncertainty propagation analysis extended sparse grid maximum entropy principle extended Gauss integration Rosenblatt transformation high-order moments analysis

3D bare-hand interactions enabling ubiquitous interactions with smart objects

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Advances in Manufacturing 2020年第2期8卷 133-143页

作者： S.K.Ong X.Wang A.y.c.Nee Department of Mechanical Engineering Faculty of EngineeringNational University of SingaporeSingapore

Ubiquitous augmented reality(UAR)implementation can benefit smart shop floor operations *** from a user's first-person view can support and provide the user with suitable and comprehensive information without him/her being distracted from ongoing tasks.A natural hand-based interaction interface,namely,a mobile bare-hand interface(MBHI),is proposed to assist a user in exploring and navigating a large amount of information for a task in the user's first-person *** integration of a smart shop floor and UAR-based MBHI is particularly challenging.A real shop floor environment is composed of challenging conditions for the implementation of UAR,e.g.,messy backgrounds and significant changes in illumination ***,the MBHI is required to provide precise and quick responses to minimize the dificulty of a user's *** this study,a wearable UAR system integrated with an MBH is proposed to augment the shop floor environment with smart information.A case study is implemented to demonstrate the practicality and effectiveness of the proposed UAR and MBHI system.

关键词： Augmented reality(AR) Mobile bare-hand interaction(MBH) Smart objects(SOs) Manufacturing shop-floor

characterization of face-centered cubic structure and deformation mechanisms in high energy shot peening process of Tc17

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Journal of Materials Science & Technology 2022年第15期110卷 136-151页

作者： c.y.ng M.Q.Li y.G.Liu School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China

The face-centered cubic structure(fcc)and its deformation behaviors,as well as the distinctive role of fcc-Ti in nanoc.y.tallization in Tc17 subjected to high energy shot peening(HESP),were investigated by using comprehensive high-resolution transmission electron microscopy(HRTEM).The results showed that there was a stress-induced fcc-Ti in Tc17 with a lattice constant of 0.420–0.433 nm and the B-type orientation relationship between the hcp-Ti and the fcc-Ti as[2-1-10]_(hcp)//[-110]_(fcc)and(0001)_(hcp)//(111)_(fcc),which was accomplished by the gliding of Shockley partial dislocations with Burgers vector of 1/3[01-10]on the basal *** deformation twinning dominated the subsequent deformation of fcc-Ti,producing two types of{111}twins with different *** them,the I-type twin with complete structure was generated by successive gliding of Shockley partial dislocations with the same Burgers vector of 1/6[11-2].In contrast,the cooperative slip of three Shockley partials,whose sum of Burgers vectors was equal to zero,produced the II-type twin with zero net macroscopic *** then,the emission of Shockley partial with the Burgers vector of 1/6[11-2]on every three(111)fccplanes resulted in the formation of a 9R *** to the dissociation effect of lamellar fcc-Ti and the superior deformation ability of fcc structure,the occurrence of fcc-Ti effectively promoted surface nanoc.y.tallization of Tc17.

关键词： Tc17 Severe plastic deformation Stress-induced phase transformation Deformation twinning Nanoc.y.tallization

Effect of terrain and building structures on the airflow in an airport

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第6期13卷 461-468页

作者： Dennis y. c. LEUNG W. y. LO W. y. cHOW P. W. cHAN Department of Mechanical Engineering The University of Hong Kong Hong Kong China Hong Kong Observatory Hong Kong China

The aim of this study was to perform computational fluid dynamics (cFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on flying aircraft, especially during landing. The cFD simulation showed that significant differences in wind speeds may occur between the north and the south runways on the western part of the HKIA under typhoon conditions with a strong north to northwesterly wind. Simulation also showed that the hanger buildings between the two runways on the western side and the nearby terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may affect the operation of landing aircraft. The cFD results for a typical typhoon case were analyzed and found to match the wind data recorded by an aircraft landing that day.

关键词： computational fluid dynamics (cFD) Hong Kong International Airport (HKIA) Low-level wind effect Hangars Terrain

Influence of Tropical cyclones on Hong Kong Air Quality

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Advances in Atmospheric Sciences 2018年第9期35卷 1177-1188页

作者： Eric c.H.cHOW Richard c.y.LI Wen ZHOU city University of Hong Kong(Shenzhen)Research Institute Shenzhen 518057China Guy carpenter Asia-Pacific climate Impact center School of Energy and Environment City University of Hong KongHong KongChina

Tropical cyclones（Tcs） constitute one of the major atmospheric activities affecting the air quality of the Pearl River Delta region. In this study, the impact of Tcs on air quality in Hong Kong during the Tc active season（July–October） from 2000 to 2015 is investigated. It is found that 57.5% of days with concentration of particulate matter with an aerodynamic diameter 10 μm（PM（10）） above the 90th percentile are related to Tc activity. Tcs in three regions, located to the east, southeast, and southwest of Hong Kong, have obvious impacts on pollutant concentration. When Tcs are located east of Hong Kong near Taiwan, 65.5%/38.7% of the days have high or extremely high PM（10）/ozone（O3） levels, which are associated with northerly wind, sinking motion, and relatively low precipitation. When Tcs are located southeast of Hong Kong, 48.1%/58.2% of the days have high pollution levels, associated mainly with continental air mass transport. When Tcs are south or west of Hong Kong, only 20.8%/16.9% of the days have high PM（10）/O3 levels, and the air quality in Hong Kong is generally good or normal due to Tc-associated precipitation, oceanic air mass transport, and an enhanced rising motion. The higher chance of high O3 days when Tcs are present between Hong Kong and Taiwan, possibly due to lower-than-normal precipitation along the east coast of china under Tc circulation. The results in this study highlight the important influence of Tc position and associated atmospheric circulations on the air quality in Hong Kong.

关键词： PM10 03 air quality HK Tc

Mathematical Simulation of Evaporating Brine by Solar Radiation for the Production of Salt

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Journal of Thermal Science 1993年第2期2卷 143-151页

作者： y.Z.Zhang c.D.Li 等 Dept.ofEngineeringThermophysics UniversityofScienceandTechnologyofCHinaHefeiAnhui230026china Scien

A computer simulation model of salt pan is *** transient behavior and the effects of various parameters of the salt pans,such as the depth of the brine layer,the absorptance of the soil surface,the thermal properties of the soil beneath the brine layer and the depth of the underground water table,on the evaporation process of salt pans are *** effects of extra insulation layer and the intensity of solar radiation are also examined.

关键词： salt pan solar radiation simulation

Thermal stress analysis method considering geometric effect of risers in sand mold casting process

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china Foundry 2014年第6期11卷 531-536页

作者： S.y.Kwak H.y.Hwang c.cho e-Design R&D Group Korea Institute of Industrial Technology (KITECH) Department of Virtual Engineering Korea University of Science and Technology(UST) Department of Mechanical Engineering Inha University

Solidif ication and f luid f low analysis using computer simulation is a current common practice. There is also a high demand for thermal stress analysis in the casting process because casting engineers want to control the defects related to thermal stresses, such as large deformation and crack generation during casting. The riser system is an essential part of preventing the shrinkage defects in the casting process, and it has a great inf luence on thermal phenomena. The analysis domain is dramatically expanded by attaching the riser system to a casting product due to its large volume, and it makes FEM mesh generation diff icult. However, it is diff icult to study and solve the above proposed problem caused by riser system using traditional analysis methods which use single numerical method such as FEM or FDM. In this paper, some research information is presented on the effects of the riser system on thermal stress analysis using a FDM/FEM hybrid method in the casting process simulation. The results show the optimal conditions for stress analysis of the riser model in order to save computation time and memory resources.

关键词： thermal stress sand mold casting riser numerical analysis hybrid method simulation