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1.
1Basic Types and Characteristics ofUrban Public Security Incidents[1,2]1·1Concept of Urban Public SecurityIncidentsUrban public security incident is a generalreference to the urban public security incidentscaused by artificially created factors,variousurban public security incidents caused by naturalfactors,and the incidents caused by the inter-acted performance of artificially created factorsand natural factors.The development andprogressive course of modern society is also thecourse of …  相似文献   

2.
The dispersion of chlorine gas in urban street canyons was numerically simulated using the fire dynamics simulator, a code developed by the National Institute of Standards and Technology of USA, which uses large eddy simulation coupled with the Smagorinsky sub-grid scale model. The unsteady flow fields were computed by solving the filtered incompressible Navier-Stokes equations under low Mach number ap-proximation by the finite difference method. The studies analyzed the influence of different street canyon configurations and aspect ratios on the flow and chlorine gas dispersion. The geometric configuration and aspect ratio both affect the vortices and the local concentration distributions in street canyons.  相似文献   

3.
In this paper, combining the technologies of Computer Supported Cooperative Work (CSCW), Workflow and Network, the authors aim to organize virtual distributed cooperative work environment (VDCWE) and expound the running mechanism of cooperative workflow and design its algorithm for monitoring of urban subway construction. And then a prototype system was built based on the above,capable of supporting user analyzing, dealing with and managing data of monitoring, and real-timely releasing corresponding information, providing interactive virtual and distributed coordination meet-environment, dynami-cally and transparently, in favor of clients' interoperaiility and solving practicing problems, and so on.  相似文献   

4.
IntroductionForexperienceefficiency ,healthyexpansion ,andgrowthratetoacity ,areasonablyimplementationofurbanplanisessen tial.Whenthedevelopmentofacityfollowsitsplan ,andresultsintheimplementationofsuchadesign ,itisnotonlythebasicre quirementofanurbanplan ,…  相似文献   

5.
1Patternselectionandver ificationoftheTGPpen stock TheYangtzeRiverWaterResourcesCommission (CWRC)submittedASub jectReportonthePatternSelectionofthePenstockinthePowerStationoftheThreeGorgesProjectinDecember,1 993,inwhichthearrangementofthepenstockswasdefinitelystated ,twotypesofstructures (internalhydraulicpressurebornesolelybypenstockandinternalhydraulicpressurejointlybornebysteellinerandreinforcedconcrete)proposed ,acomparisonbetweenthetwooptionscomprehensivelyperformed ,andsuggesti…  相似文献   

6.
Changsha was one of the most affected areas during the 2009 A (H 1N 1) influenza pandemic in China. Here, we analyze the spatial-temporal dynamics of the 2009 pan- demic across Changsha municipal districts, evaluate the relationship between case incidence and the local urban spatial structure and predict high-risk areas of influenza A (H1NI). We obtained epidemiological data on all cases of influenza A (H1NI) reported across municipal districts in Changsha dur- ing period May 2009-December 2010 and data on population density and basic geographic characteristics for 239 primary schools, 97 middle schools, 347 universities, 96 mails and markets, 674 business districts and 121 hospitals. Spatial- temporal K functions, proximity models and logistic regres- sion were used to analyze the spatial distribution pattern of influenza A (H1N1) incidence and the association between influenza A (HINI) cases and spatial risk factors and predict the infection risks. We found that the 2009 influenza A (H 1N 1 ) was driven by a transmission wave from the center of the study area to surrounding areas and reported cases increased significantly after September 2009. We also found that the distribution of influenza A (H 1N1) cases was associ- ated with population density and the presence of nearest public places, especially universities (OR = 10.166). The final pre- dictive risk map based on the multivariate logistic analysis showed high-risk areas concentrated in the center areas of the study area associated with high population density. Our find- ings support the identification of spatial risk factors and high- risk areas to guide the prioritization of preventive and miti- gation efforts against future influenza pandemics.  相似文献   

7.
Motor bikes (m-bike) and electric bikes (e-bike) are widely used in urban areas of China. Life cycle assessment of m-bike and e-bike are presented to compare their energy use and environmental emission in a life cycle span. An m-bike and an e-bike are disassembled to collect material composition data for the life cycle assessment. The results show that e-bike consumes less energy and has less global warming potential (GWP), biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), dissolved solids (DS), hydrocarbons (HC) than m-bike during life cycle. But e-bike generates more solid wastes, and more acidification potential (AP), heavy metal (HM) than m-bike. Advanced batteries and clean coal fired power plant technologies are recommended to promote e-bike use in urban area.  相似文献   

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10.
<正>The dynamical-wave routing model of the urban unsteady and non-pressure rain pipe flow was established by conservation of mass,momentum and energy,and it was solved by applying the four point implicit difference method and the pursuit method.It was obtained from the experiment checking and comparative analysis that the dynamical-wave routing model can reflect influence like attenuate and backwater when flood peak propagate in pipeline with high calculation precision and vast application scope,and it can be applied in routing of urban rain pipe flow of different slopes and inflow conditions.The routing model supplies a scientific foundation for the town rainfall piping design or checking,disaster administration of storm runoff,and so on.  相似文献   

11.
Chang’E-3 landed on the east of Sinus Iridum area on December 14, 2013, performing China’s first successful soft landing on the lunar surface. We present the results on precision orbit determination and positioning of the lander and the rover. We describe the data, modeling, and methods used to achieve position knowledge over the period December 2–21, 2014. In addition to the radiometric X-band range and Doppler tracking data, delta differential one-way ranging data are also used in the calculation, which show that they strongly improve the accuracy of the orbit reconstruction. Total position overlap differences are about 20 and 30 m for the 100 km × 100 km and 100 km× 15 km lunar orbit, respectively, increased by ~50 % with respect to CE-2 and at the same level as other lunar spacecrafts of recent era such as SELENE and lunar reconnaissance orbiter (LRO). The position error of the soft landing trajectory is less than 100 m. A kinematic statistical method is applied to determine the position of the lander and relative position of the rover with respect to the lander. The position difference of the lander is better than 50 m compared to LRO photograph result. Compared with the delta very long baseline interferometry (VLBI) group delay between the lander and the rover, the delta VLBI phase delay can improve the relative position of the rover from ~1,000 to ~1 m.  相似文献   

12.
<正>The journal of Progress in Natural.Science:Materials International sponsored and organized by both Chinese Materials Research Society(C-MRS)and International Union of Materials Research Societies(IUMRS)started to publish its first issue in November.2010.The Progress in Natural Science:Materials International provides scientists and engineers throughout the world with a central  相似文献   

13.
Flow Simulation of Urban Sewer Networks   总被引:1,自引:0,他引:1  
佘云童  茅泽育 《清华大学学报》2003,8(6):719-725,733
Flow in an urban drainage network is usually unsteady with backwater near junctions. The routing of hydrographs through a network is an important aspect of the design and analysis of urban drainage networks. Various numerical methods to analyze flow in urban drainage networks were compared and a new hybrid interpolation scheme was developed which combined time-line reachback interpolation, implicit interpolation and space-line interpolation. Numerical simulations show that the improved method more accurately models flows in urban drainage networks.  相似文献   

14.
A portable 3-component broadband digital seismic array was deployed across the Tianshan orogenic belt (TOB) to investigate the lithospheric structure. Based on receiver function analysis of the teleseismic P-wave data, a 2-D S-wave velocity profile of the boundary area of the TOB and the Tarim Basin was obtained at the depths of 0--80 km.Our results reveal a vertical and lateral inhomogeneity in the crust and uppermost mantle. Four velocity interfaces divide the crystalline crust into the upper, middle and lower crust. A low velocity zone is widely observed in the upper-middle crust. The depth of Moho varies between 42 and 52 km. At the north end of the profile the Moho dips northward with a vertical offset of 4--6 km, which implies a subduction front of the Tarim Basin into the TOB. The Moho generally appears as a velocity transitional zone except beneath two stations in the northern Tarim Basin, where the Moho is characterized by a typical velocity discontinuity. The fine velocity structure and the deep contact deformation of the crust and upper most mantle delineate the north-south lithospheric shortening and thickening in the boundary area of the TOB and the Tarim Basin, which would be helpful to constructing the geodynamical model of the intracontinental mountain-basin-coupling system.  相似文献   

15.
Chang'E-3 landed on the east of Sinus Iridum area on December 14, 2013, performing China's first successful soft landing on the lunar surface. We present the results on precision orbit determination and positioning of the lander and the rover. We and methods used to achieve period December 2-21, 2014. describe the data, modeling, position knowledge over the In addition to the radiometric X-band range and Doppler tracking data, delta differential one-way ranging data are also used in the calculation, which show that they strongly improve the accuracy of the orbit reconstruction. Total position overlap differences are about 20 and 30m for the 100km × 100km and 100 kmx 15 km lunar orbit, respectively, increased by ,- 50 % with respect to CE-2 and at the same level as other lunar spacecrafts of recent era such as SELENE and lunar reconnaissance orbiter (LRO). The position error of the soft landing trajectory is less than 100 m. A kinematic statistical method is applied to determine the position of the lander and relative position of the rover with respect to the lander. The position difference of the lander is better than 50 m compared to LRO photograph result. Compared with the delta very long baseline interferometry (VLBI) group delay between the lander and the rover, the delta VLBI phase delay can improve the relative position of the rover from ~ 1,000 to ~1 m.  相似文献   

16.
Making rural settlements of Mountainous Regions in Western Sichuan as the study objects and using symbolic statistical methods, then combining the case study of Daofu County, the paper analyzes the negative impact of the scattered rural settlements on infrastructure construction, farmers' income increase and mountain ecological reconstruction in mountainous regions of western Sichuan. The results indicate that economic density is positively related to both rural settlements density (R^2=0.73) and rural population density (R^2=0.77), and it is the same for relationship between towns density and rural settlements density (R^2=0.88) and between towns density and economic density (R^2=0.71), and the scattered distribution pattern of the rural settlements and shortage of economic centers is a major factor to the lagged socioeconomic development. On the eco-economic zoning to Daofu County, the paper indicates the spatial distribution model and the industrial development model of the rural settlements need to be changed, and rural population should be concentrated in larger rural settlements with development of off-farm industries while infrastructure construction is to reinforced.  相似文献   

17.
irectly the development of regional economy,forefront production and common life of the people.Its education focuses more or less on the teaching,training and research on t  相似文献   

18.
The research of the paleoflood remains from archaeological sites is one of the most important jobs in the environmental archaeology.Based on the traditional archaeological methods and the archaeological finds from the Yuxi site,Fengdu County of Chongqing,the paper analyzes the difference between the cultural layers and the possible paleoflood layers from various angles,such as contents,shapes of gravels,pottery,etc.,identifies the possible paleoflood deposit layers,i.e.the paleoflood remains of the Yangtze River,and discusses the periodicity of the floods.  相似文献   

19.
老人与海是海明威的著名著作,通过它我们可以看到海明威对象征主义的运用。当然,他同时运用了现实主义,比喻意义以及冰山理论等。但是这里仅着重研究象征主义,特别是圣地亚哥的宗教意义以及马洛林的象征意义。  相似文献   

20.
于润梅 《科技信息》2007,(3):128-128
Speaking is a productive skill and it is acknowledged to be hard for learners to master.Certain elements related to phonetics in discourse analysis,which play a significant role in EFL teaching of speaking,seem to be neglected.This paper analyses three of these elements:pause,intonation and tonic syllable,and their application in the teaching of speaking.  相似文献   

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