检索结果-南通市图书馆

Impacts of environmental factors on urban heating

Journal of Environmental Sciences 2010年第12期22卷 1903-1909页

作者： Rizwan Ahmed Memon dennis y.c.leung Department of Mechanical Engineering Mehran University of Engineering & Technology Department of Mechanical Engineering The University of Hong Kong School of Energy and Environment City University of Hong Kong

This study investigated the impact of important environmental variables （i.e., wind speed, solar radiation and cloud cover） on urban heating. Meteorological parameters for fifteen years （from 1990 to 2005）, collected at a well developed and densely populated commercial area （Tsim Sha Tsui, Hong Kong）, were analyzed in details. Urban heat island intensity （UHII）, a well known indicator of urban heating, has been determined as the spatially averaged air-temperature difference between Tsim Sha Tsui and Ta Kwu Ling （a thinly populated rural area with lush vegetation）. Results showed that the UHII and cloud cover have increased by around 9.3% and 4%, respectively, whereas the wind speed and solar radiation have decreased by around 24% and 8.5%, respectively. The month of December experienced the highest UHII （10.2℃） but the lowest wind speed （2.6 m/sec） and cloud cover （3.8 oktas）. conversely, the month of April observed the highest increases in the UHII （over 100%） and the highest decreases in wind speed （over 40 %） over fifteen years. Notably, the increases in the UHII and reductions in the wind speed were the highest during the night-time and early morning. conversely, the intensity of solar radiation reduced while the intensity of urban cool island （UcII） increased during solar noon-time. Results demonstrated strong negative correlation between the UHII and wind speed （coefficient of determination, R^2 = 0.8） but no negative correlation between UcII and solar radiation attenuation. A possible negative correlation between UHII and cloud cover was investigated but could not be substantiated.

关键词： urban heat island urban cool island wind speed cloud cover

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical study on the ozone formation inside street canyons using a chemistry box model

引用

Journal of Environmental Sciences 2008年第7期20卷 832-837页

作者： chun-Ho Liu dennis y.c.leung Department of Mechanical Engineering The University of Hong KongHong Kong.

Tropospheric ozone is a secondary air pollutant produced in the presence of nitrogen oxides (NO_x),volatile organic compounds (VOcs),and solar *** an urban environment,ground-level vehicular exhaust is the major anthropogenic source of ozone *** the cases of street canyons,pollutant dilution is weakened by the surrounding buildings that creates localized high concentration of NO_x and VOcs,and thus leads to high potential of ozone *** considering the major physical and chemical p...

关键词： volatile organic compounds VOcs-to-NO_x ratio air quality vehicular emission chemistry box model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of building aspect ratio,diurnal heating scenario,and wind speed on reactive pollutant dispersion in urban street canyons

引用

Journal of Environmental Sciences 2012年第12期24卷 2091-2103页

作者： Nelson y.O.Tong dennis y.c.leung Department of Mechanical Engineering The University of Hong Kong

A photochemistry coupled computational fluid dynamics （cFD） based numerical model has been developed to model the reactive pollutant dispersion within urban street canyons, particularly integrating the interrelationship among diurnal heating scenario （solar radiation affections in nighttime, daytime, and sun-rise/set）, wind speed, building aspect ratio （building-height-to-street-width）, and dispersion of reactive gases, specifically nitric oxide （NO）, nitrogen dioxide （NO2） and ozone （O3） such that a higher standard of air quality in metropolitan cities can be achieved. Validation has been done with both experimental and numerical results on flow and temperature fields in a street canyon with bottom heating, which justifies the accuracy of the current model. The model was applied to idealized street canyons of different aspect ratios from 0.5 to 8 with two different ambient wind speeds under different diurnal heating scenarios to estimate the influences of different aforementioned parameters on the chemical evolution of NO, NO2 and 03. Detailed analyses of vertical profiles of pollutant concentrations showed that different diurnal heating scenarios could substantially affect the reactive gases exchange between the street canyon and air aloft, followed by respective dispersion and reaction. Higher building aspect ratio and stronger ambient wind speed were revealed to be, in general, responsible for enhanced entrainment of 03 concentrations into the street canyons along windward walls under all diurnal heating scenarios. comparatively, particular attention can be paid on the windward wall heating and nighttime uniform surface heating scenarios.

关键词： photochemistry reactive pollutant dispersion building aspect ratio diurnal heating scenario wind speed urban streetcanyon

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

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

引用

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

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Aluminum-air battery with cotton substrate:controlling the discharge capacity by electrolyte pre-deposition

引用

Green Energy & Environment 2023年第3期8卷 757-766页

作者： Wending Pan yifei Wang Holly y.H.Kwok dennis y.c.leung Department of Mechanical Engineering The University of Hong KongHong KongChina

conventional Al-air battery has many disadvantages for miniwatt applications,such as the complex water management,bulky electrolyte storage and potential leakage ***,the self-corrosion of Al anode continues even when the electrolyte flow is stopped,leading to great Al *** tackle these issues,an innovative cotton-based aluminum-air battery is developed in this *** of flowing alkaline solution,cotton substrate pre-deposited with solid alkaline is used,together with a small water reservoir to continuously wet the cotton and dissolve the alkaline *** this manner,the battery can be mechanically recharged by replacing the cotton substrate and refilling the water reservoir,while the thick aluminum anode can be reused for tens of times until complete *** cotton substrate shows excellent ability for the storage and transportation of alkaline electrolyte,leading to a high peak power density of 73 mW cm^(-2) and a high specific energy of 930 mW h g^(-1).Moreover,the battery discharge capacity is found to be linear to the loading of pre-deposited alkaline,so that it can be precisely controlled according to the mission profile to avoid Al ***,a two-cell battery pack with common water reservoir is developed,which can provide a voltage of 2.7 V and a power output of 223.8 *** further scaling-up and stacking,this cotton-based Al-air battery system with low cost and high energy density is very promising for recharging miniwatt electronics in the outdoor environment.

关键词： Al-air battery cotton-based Electrolyte pre-deposition capacity control Miniwatt electronics

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Low-cost and efficient Mn/ceO_(2) catalyst for photocatalytic VOcs degradation via scalable colloidal solution combustion synthesis method

引用

Journal of Materials Science & Technology 2022年第21期116卷 169-179页

作者： yingguang Zhang Muyan Wu yifei Wang Xiaolong Zhao dennis y.c.leung Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen 518000China

colloidal solution combustion synthesis(cScS)is a simple and easy method for mass-production of crystalline nanomaterials with tunable pore *** this work,mesoporous Mn/ceO_(2) catalysts were fabricated via cScS method coupled with a dip-coating process and used for photocatalytic oxidation(PcO)of *** vacuum ultraviolet(VUV)irradiation,a high toluene removal efficiency of about 92%was achieved with a toluene reaction rate of about 118μmol/g/h in a continuous flow reactor.A possible degradation pathway was proposed based on the analysis of intermediates by Fourier transform infrared photoluminescence spectra(FTIR)and *** temperature-programmed reduction(H_(2)-TPR),Brunauer-Emmett-Teller(BET)surface areas,photoluminescence spectra(PL)spectra and X-ray photoelectron spectroscopy(XPS)were carried out to analyze physical and chemical properties of the *** with Mn_(x)ce_(1-x)O_(2) catalysts synthesized by one step cScS method,Mn/ceO_(2) has a higher photocatalytic activity,which is attributed to the presence of higher contents of ce^(3+),Mn^(2+)and Mn^(3+)*** presence of higher contents of these species plays a key role in the activity enhancement of toluene oxidation and ozone *** method is facile,efficient and scalable,and it may become a promising industrial application technology for catalyst synthesis in the near future.

关键词： Mesoporous ceO_(2) Manganese modification Scalable synthesis Photocatalysis VOcs abatement

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

GO-modified flexible polymer nanocomposites fabricated via 3D stereolithography

引用

Frontiers of chemical Science and Engineering 2019年第4期13卷 736-743页

作者： chi Him Alpha Tsang Adilet Zhakeyev dennis y.c.leung Jin Xuan School of Environmental Sciences and Engineering Sun Yat-Sen UniversityGuangzhou 510006China Department of Mechanical Engineering The University of Hong KongHong KongChina Department of chemical Engineering Loughborough UniversityLoughboroughLE113TUUK

Graphene oxide(GO)induced enhancement of elastomer properties showed a great deal of potential in recent years,but it is still limited by the barrier of the complicated synthesis ***(SLA),used in fabrication of thermosets and very recently in“flexible”polymers with elastomeric properties,presents itself as simple and user-friendly method for integration of GO into *** this work,it was first time demonstrated that GO loadings can be incorporated into commercial flexible photopolymer resins to successfully fabricate GO/elastomer nanocomposites via readily accessible,consumer-oriented SLA *** material properties of the resulting polymer was characterized and *** mechanical strength,stiffness,and the elongation of the resulting polymer decreased with the addition of *** thermal properties were also adversely affected upon the increase in the GO content based on differential scanning calorimetry and thermogravimetric analysis *** was proposed that the GO agglomerates within the 3D printed composites,can result in significant change in both mechanical and thermal properties of the resulting *** study demonstrated the possibility for the development of the GO/elastomer nanocomposites after the optimization of the GO/“Hexible”photoreactive resin formulation for SLA with suitable annealing process of the composite in future.

关键词： graphene oxide polymer flexible 3D printing stereolithography

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Solid-state Al-air battery with an ethanol gel electrolyte

引用

Green Energy & Environment 2023年第4期8卷 1117-1127页

作者： yifei Wang Wending Pan Kee Wah Leong Shijing Luo Xiaolong Zhao dennis y.c.leung School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhenChina Department of Mechanical Engineering The University of Hong KongHong KongChina

Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm^(-2), *** studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.

关键词： Al-air battery Gel electrolyte Ethanol gel Al corrosion Polyethylene oxide

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

computational fluid dynamics simulation of the wind flow over an airport terminal building

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第6期11卷 389-401页

作者： chun-ho LIU dennis y.c.leung Alex c.S.MAN P.W.cHAN Department of Mechanical Engineering The University of Hong Kong Hong Kong Observatory

Turbulence in the wake generated by wind flow over buildings or obstacles may produce complex flow patterns in downstream *** include the recirculating flow and wind deficit areas behind an airport terminal building and their potential impacts on the aircraft landing on nearby runways.A computational fluid dynamics(cFD) simulation of the wind flow over an airport terminal building was performed in this study of the effect of the building wake on landing *** normal meteorological conditions,the studied airport terminal building causes limited effects on landing aircraft because most of the aircraft have already landed before entering the turbulent wake *** simulating the approach of a tropical cyclone,additional cFD sensitivity tests were performed to study the impacts of building wake under extreme meteorological *** was found that,in a narrow range of prevalent wind directions with wind speeds larger than a certain threshold value,a substantial drop in wind speed(>3.6 m/s) along the glide path of aircraft was observed in the building *** cFD results also showed that under the most critical situation,a drop in wind speed as large as 6.4 m/s occurred right at the touchdown point of landing aircraft on the runway,an effect which may have a significant impact on aircraft *** study indicated that a comprehensive analysis of the potential impacts of building wake on aircraft operations should be carried out for airport terminals and associated buildings in airfields to ensure safe aviation operation under all meteorological conditions and to facilitate implementation of precautionary measures.

关键词： Aviation safety Building aerodynamics computational fluid dynamics (cFD) k-e turbulence model Tropicalcyclone

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Paper-based aqueous Al ion battery with water-in-salt electrolyte

引用

Green Energy & Environment 2023年第5期8卷 1380-1388页

作者： yifei Wang Wending Pan Kee Wah Leong yingguang Zhang Xiaolong Zhao Shijing Luo dennis y.c.leung School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen518055China Department of Mechanical Engineering The University of Hong KongHong KongChina

Low-cost,flexible and safe battery technology is the key to the widespread usage of wearable electronics,among which the aqueous Al ion battery with water-in-salt electrolyte is a promising *** this work,a flexible aqueous Al ion battery is developed using cellulose paper as *** water-in-salt electrolyte is stored inside the paper,while the electrodes are either printed or attached on the paper surface,leading to a lightweight and thin-film battery ***,this battery can tolerate a charge and discharge rate as high as 4 A g^(-1) without losing its storage *** charge voltage is around 2.2 V,while the discharge plateau of 1.6–1.8 V is among the highest in reported aqueous Al ion batteries,together with a high discharge specific capacity of~140 mAh g^(-1).However,due to the water electrolysis side reaction,the faradaic efficiency can only reach 85%with a cycle life of 250 due to the dry out of *** from using flexible materials and aqueous electrolyte,this paper-based Al ion battery can tolerate various deformations such as bending,rolling and even puncturing without losing its *** two single cells are connected in series,the battery pack can provide a charge voltage of 4.3 V and a discharge plateau as high as 3–3.6 V,which are very close to commercial Li ion *** a cheap,flexible and safe battery technology may be widely applied in low-cost and large-quantity applications,such as RFID tags,smart packages and wearable biosensors in the future.

关键词： Al ion battery Aqueous electrolyte Water-in-salt Paper battery Flexible battery

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：