检索结果-南通市图书馆

Theoretical and Empidcal Study on Urban Population Carrying Capacity:Case of Haidian District in Beijing

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

Chinese Journal of Population,Resources and Environment 2008年第2期6卷 25-30页

作者： Zhang Lihua Chert Gang Xu Xiaoxin Liu Huiwu Institute of Policy and Management Chinese Academy of Sciences Beijing 100080 China CClD consulting Co. Ltd Beijing 100044 China

The measurement of urban population carrying capac- ity is the basis for cities' sustainable ***,the traditional study on population carrying capacity which was based on food supply is not applicable to the single urban *** paper built a model for the analysis of urban carrying capacity, and took Haidian District in Beijing as an example to calculate the urban carrying capacity of Haidian District in the future,which was the basis for the improvement of the population carrying *** study would also provide a reference to the meas- urement of the urban population carrying capacity for other cities and districts in China.

关键词： population carrying capacity sustainable development case study

Vertical shaking table tests on the structure with viscoelastic multi-dimensional earthquake isolation and mitigation devices

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第10期52卷 2869-2876页

作者： XU ZhaoDong SHI BenQiang WU KeYi ZENG Xiao RC&PC Key Laboratory of Education Ministry Southeast UniversityNanjing 210096China Shun De Country Garden Holdings Co.ltd Shunde 528312China Huaxin Past&Telecom consulting and Designing Institute Co.ltd Hangzhou 310014China

The viscoelastic multi-dimensional earthquake isolation and mitigation device is a new kind of passive control device, which can perform its "name-giving" task of earthquake isolation and earthquake mitigation simultaneously. In order to quantify its vertical earthquake isolation and mitigation effect on structures, firstly, shaking table tests on steel frame structures with and without the devices were carried out; secondly, analysis on dynamic characteristics and dynamic responses of the structures was also performed; furthermore, the finite element analytical results and the experimental results were compared. It can be shown from the analytical and experimental results that the devices have noticeable earthquake isolation and mitigation effect in the vertical direction.

关键词： earthquake isolation and mitigation shaking table test finite element dynamic response

Preparation of reverse osmosis membrane with high permselectivity and anti-biofouling properties for desalination

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2022年第7期16卷 73-86页

作者： Xinxia Tian Hui Yu Jun Yang Xiaotai Zhang Man Zhao Yang Yang Wei Sun Yangyang Wei Yin Zhang Jian Wang Zhun Ma The Institute of Seawater Desalination and Multipurpose Utilization MNR(Tianjin)Tianjin300192China Tianjin Huanke Environment consulting CO. LTDTianjin300191China College of Chemical and Biological Engineering Shandong University of Science and TechnologyQingdao266590China

High performance is essential for the polyamide(PA)reverse osmosis(RO)membranes during the desalination ***,RO membranes with high permselectivity and anti-biofouling properties were fabricated by nanoparticles incorporation and anti-biofouling ***(HT)incorporation was performed with a dual role,enhancing water flux and acting as grafting *** HT incorporation increased the water flux without sacrificing the salt rejection,compensating for the loss caused by the following grafting *** exposed surface of HT acted as grafting sites for anti-biofouling agent dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride(DMOTPAC).The combination of HT incorporation and DMOTPAC grafting endowed RO membranes with high permselectivity and anti-biofouling *** water flux of the modified membrane PA-HT-0.06 was 49.8 L/m^(2)·h,which was 16.4%higher than that of the pristine *** salt rejection of PA-HT-0.06 was 99.1%,which was comparable to that of the pristine *** to the fouling of negatively charged lysozyme,the modified membrane’s water flux recovery was superior to that of the pristine membrane(e.g.86.8%of PA-HT-0.06 compared to 78.2%of PA-pristine).The sterilization rates of PA-HT-0.06 for *** and *** were 97.3%and 98.7%,much higher than those of the pristine membrane(24.0%for *** and 26.7%for ***).

关键词： Anti-biofouling grafting Nanoparticle incorporation Sterilization rates Water flux Water flux recovery

Field and laboratory experimental studies on hard-rock tunnel excavation based on disc cutter coupled with high-pressure waterjet

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2023年第9期17卷 1370-1386页

作者： He FEI Yiqiang LU Jinliang ZHANG Xingchen LUO Yimin XIA College of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China China Railway Engineering Equipment Group Co. Ltd.Zhengzhou 450016China College of Civil Engineering Tongji UniversityShanghai 200092China Yellow River Engineering consulting Co. Ltd.Zhengzhou 450003China

The tunnel boring machine(TBM)is typically used in hard-rock tunnel *** to the unsatisfactory adaptability of TBM to the surrounding rock,when crossing high-strength and high-wear strata,the TBM can easily cause defects,such as abnormal wear on cutters and overload damage to bearings,thus affecting the construction efficiency and ***,high-pressure waterjet technology should be applied to assist in rock breaking for efficient TBM *** this study,the effects of water pressure,nozzle diameter,and nozzle speed on cutting are investigated via laboratory experiments of cutting hard rock using high-pressure *** penetration performance of the TBM under different water pressures is investigated via a field industrial penetration *** results show that high-pressure waterjets are highly efficient for rock breaking and are suitable for industrial applications,as they can accommodate the advancing speed of the TBM and achieve high-efficiency rock ***,during the operation of high-pressure waterjets,the ambient temperature and waterjet temperature in the tunnel increase significantly,which weakens the cooling effect of the cutterhead and decreases the construction efficiency of the ***,temperature control and cooling measures for high-pressure waterjets during their long-term operation must be *** study provides a useful reference for the design and construction of high-pressure water-jet-assisted cutterheads for breaking road headers.

关键词： tunnel boring machine hard-rock cutting free face disc cutter rock-cutting efficiency

A Wind Power Prediction Framework for Distributed Power Grids

在线全文

学校读者我要写书评

暂无评论

Energy Engineering 2024年第5期121卷 1291-1307页

作者： Bin Chen Ziyang Li Shipeng Li Qingzhou Zhao Xingdou Liu Power Grid Design Institute Shandong Electric Power Engineering Consulting Institute Co.Ltd.Jinan250013China School of Electrical Engineering Shandong UniversityJinan250012China

To reduce carbon emissions,clean energy is being integrated into the power *** power is connected to the grid in a distributed form,but its high variability poses a challenge to grid *** article combines wind turbine monitoring data with numerical weather prediction(NWP)data to create a suitable wind power prediction framework for distributed ***,high-precision NWP of the turbine range is achieved using weather research and forecasting models(WRF),and Kriging interpolation locates predicted meteorological data at the turbine ***,a preliminary predicted power series is obtained based on the fan’s wind speed-power conversion curve,and historical power is reconstructed using variational mode decomposition(VMD)filtering to form input variables in chronological ***,input variables of a single turbine enter the temporal convolutional network(TCN)to complete initial feature extraction,and then integrate the outputs of all TCN layers using Long Short Term Memory Networks(LSTM)to obtain power prediction sequences for all turbine *** proposed method was tested on a wind farm connected to a distributed power grid,and the results showed it to be superior to existing typical methods.

关键词： Wind power prediction distributed power grid WRF mode deep learning variational mode decomposition

Study on Key Technology of Using Shell Sand as Backfill for Sea Reclamation

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

China Ocean Engineering 2005年第4期19卷 647-658页

作者：郦能惠瞿亦容何文钦陈晖 Nanjing Hydraulic Research Institute Nanjing210029China CTE Guangzhou Design & consulting Corp. Guangzhou 510230China CNOOC Fujian LNG Co. ltd. Fuzhou350001China

The results of a study on the key technology of using shell sand, a kind of sea sand, as backfill for sea reclamation are described briefly. Iaboratory tests show that the physical and mechanical properties of shell sand are as good as normal quartz sand. Based on the chemical test and durability test of shell sand it could be concluded that the influence of corrosion of shell sand by acid rain and sea water might be ignored in the evaluation of the safety and durability of the engineering project. The results of field improvement tests show that the bearing capacity of shell sand backfill foundation is more than 200 kPa after vibmflotation improvement or dynamic compaction improvement. The shell sand is a good backfill material for sea reclamation.

关键词： sea reclamation backfill shell sand durability earthquake response ground improvement

Non-symmetrical levee breaching processes in a channel bend due to overtopping

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2018年第2期33卷 208-215页

作者： Songbai Wu Minghui Yu Hongyan Wei Yanjie Liang Jing Zeng State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Institute of Earth Surface System and Hazards Northwest University Yellow River Engineering consulting Co. Ltd.

A series of experiments were done to reveal the overtopping breaching process of non-cohesive and cohesive levees in a U-bend flume. The flood hydrograph and breaching geometry were measured and analyzed in detail. The results show that the levee breaching processes can be briefly divided into four stages: slope erosion, longitudinal headward gully-cutting, lateral erosion, and relative stabilization. For non-cohesive levees, non-symmetrical lateral development of the breach occurs throughout the four stages, and the final non-symmetrical coefficient is approximately 2.2-2.6. Larger flow discharge or higher water level can accelerate the breaching process, while coarser sands tend to accelerate the process initially but depress the process at the end. The fluvial erosion rate of a non-cohesive breach shows a power-function relation with the excess wall shear stress. For cohesive levees, a plateau forms in the breach partially blocking the flow in the first two stages. The breach flow is approximately perpendicular to the levee body, and, thus, the erosion rates of the two breach sides are almost the ***-symmetrical lateral development mainly occurs in the third stage when the deep gully forms. The final non-symmetrical coefficient is approximately 2.7-3.3. It is expected that these findings can provide a valuable experimental dataset and a theoretical basis for breach closure and flood alleviation.

关键词： Overtopping Levee breach Hydrodynamic model Flume experiment

Spatiotemporal variations in climatic factors， catchment characteristic induced runoff changes with multi-time scales across the contiguous United States

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Earth Science 2021年

作者： Xinglong Gong Shuping Du Fengyu Li Yibo Ding School of Water Conservancy & Civil Engineering， Northeast Agricultural University Yellow River Engineering consulting Co.， ltd.

Previous works were mainly concentrated on long-term average runoff alterations， and extreme temperatures and watershed conditions are little analyzed. In this study， we collected gauged river flow and meteorological data time series from 1916 to 2015 and 1941 to 2015 across the contiguous United States （CONUS） for 188 catchments to investigate the temporal trends and spatial features of runoff changes at multi-time scales. We also analyzed the relationships between runoff changes and climatic factors. Median descriptive statistics and Budyko coupled climate elasticity methods were used to calculate runoff elasticity in each time scale. The original Mann-Kendall trend test was used to test their trend significance in four times-cales （11， 20， 40， and 60 a）， respectively. The results show that the trend of runoff changes is more significant in high time scales; Total changes are heterogeneous over CONUS. After the 1970s， increases of up to 27% decade;were mainly concentrated in the mid-northern regions. Maximum temperature and catchment characteristics are vital factors for runoff alteration; runoff changes are independent of rainfall， and wet regions tend to have lower changes. These findings could help develop better regional water resource planning and management.

关键词：

MULTI-CHANNEL TRANSMISSION STRATEGY FOR DYNAMIC SPECTRUM ACCESS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Electronics(China) 2010年第3期27卷 345-352页

作者： Wu Yingxiao Yang Zhen Huaxin consulting Co. Ltd Hangzhou 310014 China Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China

Cognitive radio is a promising technology that deals with the scarcity of radio spectrum. In this paper, we propose a new multi-channel transmission strategy for dynamic spectrum access in cognitive radio network. Starting with the model of spectrum activities, we present the multi-channel transmission strategy which has primary user's protection mechanism to improve the spectrum efficiency and study its performance under perfect and imperfect sensing. Numerical example results reveal that the performance of the proposed strategy has the superiority with respect to capacity performance of cognitive users and the protection of primary users.

关键词： Transmission strategy Dynamic spectrum access Multiple channels