检索结果-南通市图书馆

The recirculation flow after different cross-section shaped high-rise buildings with applications to ventilation assessment and drag parameterization

引用

Building Simulation 2024年第4期17卷 509-524页

作者： keyi chen Ziwei Mo Jian Hang School of Atmospheric Sciences Sun Yat-sen University&Southern Marine Science and Engineering Guangdong LaboratoryZhuhai519082China Key Laboratory of Tropical Atmosphere-Ocean System Ministry of EducationZhuhai519000China

The building cross-section shape significantly affects the flow characteristics around buildings,especially the recirculation region behind the high-rise building.Eight generic building shapes including square,triangle,octagon,T-shaped,cross-shaped,#-shaped,H-shaped and L-shaped are examined to elucidate their effects on the flow patterns,recirculation length L and areas A using computational fluid dynamics(CFD)simulations with Reynolds-averaged Navier-Stokes(RANS)approach.The sizes and positions of the vortexes behind the buildings are found to be substantially affected by the building shapes and subsequently changing the recirculation flows.The recirculation length L is in the range of 1.6b-2.6b with an average of 2b.The maximum L is found for L-shaped building(2.6b)while the shortest behind octagon building(1.6b).The vertical recirculation area Av is in the range of 1.5b^(2)-3.2b^(2)and horizontal area Ah in 0.9b^(2)-2.2b^(2).The L,Av and Ah generally increase with increasing approaching frontal area when the wind direction changes but subject to the dent structures of the#-shaped and cross-shaped buildings.The area-averaged wind velocity ratio(AVR),which is proposed to assess the ventilation performance,is in the range of 0.05 and 0.14,which is around a three-fold difference among the different building shapes.The drag coefficient parameterized by Ah varies significantly,suggesting that previous models without accounting for building shape effect could result in large uncertainty in the drag predictions.These findings provide important reference for improving pedestrian wind environment and shed some light on refining the urban canopy parameterization by considering the building shape effect.

关键词： recirculation region cross-section shape ventilation assessment drag parameterization computational fluid dynamics

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

Polymer electrolytes reinforced by 2D fluorinated filler for all-solidstate Li-Fe-F conversion-type lithium metal batteries

引用

Nano Research 2023年第6期16卷 8469-8477页

作者： Meng Lei Xiaoxue Wu Yangyang Liu keyi chen Jiulin Hu Chilin Li State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201899China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory of Materials for Energy Conversion Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201899China Frontiers Science Center for Transformative Molecules School of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The polyethylene oxide(PEO)based solid-state batteries are considered as promising candidates for the next-generation Li metal batteries with high energy density and safety.However,the low Li-ion conductivity and high-voltage endurability hinder the further applications of PEO-based electrolytes.To overcome these issues,herein two-dimensional(2D)CeF_(3)nanoplates with maximally exposed[001]crystal faces are introduced into the PEO matrix to expand the electrochemical window and improve Liion conduction and transport.The optimized crystal shape and crystal face anisotropy of CeF_(3)nanoplate filler reduce the crystallinity of composite solid polymer electrolyte(CSPE)via its Lewis acid-base interaction with ether oxygen of PEO.The Liaffinity[100]and Li-repellent[001]crystal faces of CeF_(3)nanoplates synergistically realize the dissociation of lithium bis(trifluoromethanesulfonyl)imide(LiTFSI),fast Li-adsorption/desorption,and Li+migration.The optimized CSPE-0.1CeF_(3)membrane enables the achievement of Li metal batteries with high endurability and stability,from the kinetically favorable Li/Li symmetric cells with long-term cycling over 8000 h.The highly reversible Li/LiFePO_(4) cells exhibit a capacity retention of 109.2 mAh·g^(−1)after 1000 cycles at 1 C,corresponding to a low capacity fading rate of 0.026%per cycle.The conversion-type allsolid-state Li/CSPE-0.1CeF_(3)/FeF_(3)cells show a high reversible capacity of 201.9 mAh·g^(−1)after long-term 600 cycles and of 231.1 mAh·g^(−1)at an ultra-high rate of 5 C.

关键词： Polymer electrolytes 2D fluoride filler solid-state batteries Li-Fe-F conversion cathodes Li metal anodes

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

Tailored deep-eutectic solvent method to enable 3D porous iron fluoride bricks for conversion-type lithium batteries

引用

Journal of Energy Chemistry 2023年第3期78卷 178-187,I0006页

作者： Chuanzhong Lai keyi chen Yongjian Zheng Junwei Meng Jiulin Hu Chilin Li CAS Key Laboratory of Materials for Energy Conversion Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201899China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of High Performance Ceramics and Superﬁne Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201899China

Conversion-type fluoride cathode can provide considerable energy density for Li batteries,however its scalable and facile synthesis strategies are still lacking.Here,a novel Fe-based deep eutectic solvent composed of nitrite and methylsulfonylmethane is proposed as both the reaction medium and precursor to synthesize O-doped FeF3porous bricks.This method is cheaper,safe,mildly operable,environmentally friendly and recyclable for non-fluorinated metal cations.The homogenization of charge and mass transport in cathode network effectively mitigates the volume extrusion and electrode coarsening even for the micro-sized monolithic particles.The Co-solvation modulated fluoride cathode delivers high reversible capacity in a wide temperature range(486 and 235 mA h g^(-1)at 25℃ and-20℃ respectively),excellent rate performance(312 mA h g^(-1)at 1000 mA g^(-1)),corresponding to an energy density as high as672.1 W h kg^(-1)under a power density of 2154.3 W kg^(-1).The successful operation of fluoride pouchcell with a capacity exceeding 450 mA h g^(-1)(even under thin Li foil and lean electrolyte conditions) indicates its potentiality of commercial application.

关键词： Ironﬂuoride Deep-Eutectic solvent Conversion cathode Li batteries Porous brick structure

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

Nanodiamonds decorated yolk-shell ZnFe_(2)O_(4) sphere as magnetically separable and recyclable composite for boosting antibiotic degradation performance

引用

Chinese Journal of Chemical Engineering 2023年第2期54卷 162-172页

作者： Jingjing Pan Haoran Sun keyi chen Yuhao Zhang Pengnian Shan Weilong Shi Feng Guo School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003China School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China College of Chemistry Zhengzhou UniversityZhengzhou 450001China

Photocatalysis is an environmentally friendly and energy-saving technology, which can effectively remove persistent dangerous pollutants in the water. Pitifully, optical absorption capacity and carrier separation have become major bottlenecks for marvelous photocatalytic performance of photocatalysts.Herein, to address these issue, Nanodiamonds/yolk-shell ZnFe_(2)O_(4) spheres(NDs/ZFO) nanocomposites were successfully constructed via a facile two-step of solvothermal and calcination methods. The synthesized optimal NDs/ZFO-10 nanocomposite exhibits superior photocatalytic degradation activity of antibiotic under visible light, approximately 85% of the total tetracycline(TC) is degraded, and this photocatalyst shows durable cycling stability. This stems from two aspects of refinement: improvement of light absorption capacity and photo-induced charges migration and separation. In addition, the NDs/ZFO composite photocatalyst features excellent magnetic recovery capability, facilitating the recovery of photocatalyst in industry. This study opens a new chapter in the combination of NDs with magnetic materials, and deepens the understanding of the application of NDs modified composite photocatalysts.

关键词： Nanodiamonds ZnFe_(2)O_(4) Photocatalytic Heterojunction Antibiotic degradation

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

中国城市人口规模分布研究

引用

现代经济探讨 2024年第7期 1-16页

作者：张莉陈可怡中山大学国际金融学院珠海519085 中观经济学与区域产业协同发展重点实验室广州510275

城市规模是人口流动的结果和表现,城市规模分布是否合理,关键在于不同规模城市之间能否形成分工与区域协调发展,这需要对城市规模的分布、变化进行准确度量,并探究背后的驱动因素。为此,运用中国296个地级以上城市的六普与七普人口数据... 详细信息

城市规模是人口流动的结果和表现,城市规模分布是否合理,关键在于不同规模城市之间能否形成分工与区域协调发展,这需要对城市规模的分布、变化进行准确度量,并探究背后的驱动因素。为此,运用中国296个地级以上城市的六普与七普人口数据,检验Zipf定律和Gibrat定律在中国城市规模分布上的适用性,并比较中国城市人口规模分布在2010至2020年的变化情况。基于人口普查数据的研究表明:从全国层面来看,296个地级以上城市总体不满足Gibrat定律,而Zipf定律的适用度在提高,从十年间的对比来看,人口进一步向大城市集聚,城市间规模差距变大;从中国十九个城市群内城市规模分布的情况来看,十年间绝大多数城市群内城市集中度上升,城市间规模差距变大。第一档城市群的中心城市体量突出,第二档城市群的规模体系较为平均,第三档城市群建设初见雏形。

关键词：城市规模分布 Zipf定律 Gibrat定律城市群

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

Evaluation of All-Sky Assimilation of FY-3C/MWHS-2 on Mei-yu Precipitation Forecasts over the Yangtze-Huaihe River Basin

引用

Advances in Atmospheric Sciences 2021年第8期38卷 1397-1414页

作者： Yu LI keyi chen Zhipeng XIAN School of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610025China International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

All-sky (i.e., clear, cloudy, and precipitating conditions) assimilation of microwave observations shows potentially positive impacts on the improvement of the forecasts of cloud-associated weather processes. In this study, a typical mei-yu heavy precipitation event that occurred in 2017 was investigated, and the Weather Research and Forecasting data assimilation (WRFDA) as well as its 3D-Var assimilation scheme (excluding cloud and precipitation control variables) were applied to assimilate the Fengyun-3C (FY-3C) Microwave Humidity Sounder-2 (MWHS-2) observations under clear- sky (excluding the observations that are strongly affected by ice clouds and precipitation) and all-sky conditions. Three experiments including a control experiment without assimilating any observations, clear-sky, and all-sky experiments with only FY-3C/MWHS-2 observations assimilated were carried out. The results show that the all-sky assimilation approach that provides more cloud and precipitation information and increased more than 10% of the satellite data usage than the clear-sky experiment. Meanwhile, as compared with the control experiment, the all-sky assimilation reduced nearly 0.5% of the root mean square errors in the humidity fields, leading to more accurate forecast performances regarding the distribution and intensity of heavy rainfall;but it exhibited a neutral to negative impacts on the wind and temperature. Although the system used to conduct all-sky assimilation is only able to adjust control variables for moisture-, wind-, and temperature- related variables in the presence of cloud and does not benefit directly from cloud or precipitation information, the positive effects on heavy rainfall forecasts achieved in this study indicate a potential future benefit regarding disaster prevention and mitigation.

关键词： all-sky assimilation FY-3C MWHS-2 mei-yu rainfall

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

基于GA-ELM的锂电池SOC估计及主动均衡

引用

电气工程学报 2024年第1期19卷 326-333页

作者：于仲安张军令陈可怡江西理工大学电气工程与自动化学院赣州341000

锂电池的状态估计和主动均衡是提高电池性能和延长使用寿命的关键技术,针对参数模型的荷电状态(State of charge,SOC)估计方法忽略电动汽车实际工况而导致的估计偏差较大的问题,提出一种基于遗传算法的极限学习机(GA-ELM)神经网络算法... 详细信息

锂电池的状态估计和主动均衡是提高电池性能和延长使用寿命的关键技术,针对参数模型的荷电状态(State of charge,SOC)估计方法忽略电动汽车实际工况而导致的估计偏差较大的问题,提出一种基于遗传算法的极限学习机(GA-ELM)神经网络算法来估计电池的荷电状态SOC,通过遗传算法优化了ELM的参数,提高估计精度和泛化能力,并在UDDS工况数据下进行训练与测试。同时采用双向Buck-Boost均衡拓扑结构,该拓扑结构能够快速实现电池间的能量传递,同时又降低了传递路径的复杂性。通过遗传算法的极限学习机估计出的SOC作为均衡变量,利用Matlab/Simulink仿真平台进行试验。结果表明,提出的GA-ELM神经网络平均误差为0.15%,而传统的ELM神经网络平均误差为0.56%,因此提出的神经网络能够更精确地估计SOC;同时电池组之间能够快速完成能量均衡,证明了所提方案的可行性。

关键词：遗传算法 Buck-Boost电路 SOC估计极限学习机电池均衡

来源：

维普期刊数据库

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Electrochemically driven conversion reaction in fluoride electrodes for energy storage devices

引用

npj Computational Materials 2018年第1期4卷 462-476页

作者： Chilin Li keyi chen Xuejun Zhou Joachim Maier State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050China University of Chinese Academy of Sciences Beijing 100039China Max Planck Institute for Solid State Research Heisenbergstraße 1D-70569 StuttgartGermany

Exploring electrochemically driven conversion reactions for the development of novel energy storage materials is an important topic as they can deliver higher energy densities than current Li-ion battery electrodes.Conversion-type fluorides promise particularly high energy densities by involving the light and small fluoride anion,and bond breaking can occur at relatively low Li activity(i.e.,high cell voltage).Cells based on such electrodes may become competitors to other envisaged alternatives such as Lisulfur or Li-air systems with their many unsolved thermodynamic and kinetic problems.Relevant conversion reactions are typically multiphase redox reactions characterized by nucleation and growth processes along with pronounced interfacial and mass transport phenomena.Hence significant overpotentials and nonequilibrium reaction pathways are involved.In this review,we summarize recent findings in terms of phase evolution phenomena and mechanistic features of(oxy)fluorides at different redox stages during the conversion process,enabled by advanced characterization technologies and simulation methods.It can be concluded that well-designed nanostructured architectures are helpful in mitigating kinetic problems such as the usually pronounced voltage hysteresis.In this context,doping and open-framework strategies are useful.By these tools,simple materials that are unable to allow for substantial Li nonstoichiometry(e.g.,by Li-insertable channels)may be turned into electroactive materials.

关键词： fluoride energy breaking

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

Assimilation of Feng-Yun-3B Satellite Microwave Humidity Sounder Data over Land

引用

Advances in Atmospheric Sciences 2018年第3期35卷 268-275页

作者： keyi chen Niels BORMANN Stephen ENGLISH Jiang ZHU School of Atmospheric Sciences Chengdu University of Information & Technology Chengdu Sichuan 610225 China International Centre for Climate and Environment Sciences Institute of Atmospheric Physics China Beijing 100029 China European Centre for Medium-Range Weather Forecasts Reading RG2 9AX UK

The ECMWF has been assimilating Feng-Yun-3B （FY-3B） satellite microwave humidity sounder （MWHS） data over ocean in an operational forecasting system since 24 September 2014, It is more difficult, however, to assimilate microwave observations over land and sea ice than over the open ocean due to higher uncertainties in land surface temperature, surface emissivity and less effective cloud screening. We compare approaches in which the emissivity is retrieved dynamically from MWHS channel l [150 GHz （vertical polarization）] with the use of an evolving emissivity atlas from 89 GHz observations from the MWHS onboard NOAA and EUMETSAT satellites. The assimilation of the additional data over land improves the fit of short-range forecasts to other observations, notably ATMS （Advanced Technology Microwave Sounder） humidity channels, and the forecast impacts are mainly neutral to slightly positive over the first five days. The forecast impacts are better in boreal summer and the Southern Hemisphere. These results suggest that the techniques tested allow for effective assimilation of MWHS/FY-3B data over land.

关键词： data assimilation over land Chinese satellite FY-3B Microwave Humidity Sounder

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

Growing Operational Use of FY-3 Data in the ECMWF System

引用

Advances in Atmospheric Sciences 2021年第8期38卷 1285-1298页

作者： Niels BORMANN David DUNCAN Stephen ENGLISH Sean HEALY Katrin LONITZ keyi chen Heather LAWRENCE Qifeng LU European Centre for Medium-range Weather Forecasts Reading RG29AXUnited Kingdom International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of the Chinese Academy of Sciences Beijing 100049China Department of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610225China National Satellite Meteorological Centre China Meteorological AdministrationBeijing 10081China

This paper reviews the data quality and impact of observations from the FY-3 satellite series used operationally in the ECMWF system. This includes data from the passive microwave radiometers MWHS-1, MWHS-2 and MWRI, as well as observations from the radio occultation receiver GNOS. Evaluations against background equivalents show that the quality of the observations is broadly comparable to that of similar instruments on other polar-orbiting satellites, even though biases for the passive microwave observations can be somewhat larger and more complex for some channels. An observing system experiment shows that the FY-3 instruments jointly contribute significantly to the forecast skill in the ECMWF system. Positive impact of up to 2% is seen for most variables out to the day-2 forecasts over hemispheric scales, with significant benefits for total column water vapor or for temperature and wind in the stratosphere out to day 4.

关键词： FY-3 satellite series assimilation forecast impact calibration/validation

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：