Swelter in the city: Urban greenery and its effects on temperature in Guwahati,India     

Monjit Borthakur  Anup Saikia  Kiran Sharma 《Singapore journal of tropical geography》2020,41(3):341-366

Changing urban landscape with multistoried high rises, roads and pavements is continuously reducing urban green space. These structures result in high surface temperature variation within cities. To explore the relationship between surface temperature and normalized difference vegetation index (NDVI), this study estimates two models—geographically weighted regression (GWR) and a fixed effect panel data model in relation to the Guwahati Metropolitan Area (GMA), a secondary city in north east India. The results indicate the superiority of GWR regression in presence of spatial dependence. Panel data analysis shows that the densely populated urban areas in the GMA with less than 10 per cent greenery are 1°C warmer than the sub-urban areas with 50 per cent greenery.  相似文献   

Numerical analysis and validation of weakly nonlinear ship motions and structural loads on a modern containership     

Myung-Jae Song  Kyong-Hwan Kim 《Ocean Engineering》2011,38(1):77-87

This paper aims to validate a numerical seakeeping code based on a 3D Rankine panel method by comparing its results with experimental data. Particularly, the motion response and hull-girder loads on a real modern ship, a 6500 TEU containership, are considered in this validation study. The method of solution is a 3D Rankine panel method which adopts B-spline basis function in the time domain. The numerical code is based on the weakly nonlinear scheme which considers nonlinear Froude-Krylov and restoring forces. The main focus of this study is given to investigate the nonlinear characteristics of wave-induced loads, and to validate this present scheme for industrial use in the range of low Froude number. The comparisons show that the nonlinear motions and hull-girder loads, computed by the present numerical code, have good overall agreements with experimental results. It is found that, for the better accuracy of computational results, particularly at extreme waves in oblique seas, the careful treatment of soft-spring (or compatible) system is recommended to the control of non-restoring motions such as surge, sway, and yaw.  相似文献   

中国经济增长与制度变迁的空间面板数据分析     

季民河  武占云  苏海龙  姜磊 《地域研究与开发》2011,30(6):1-5

以North的体制经济学为理论依据,将新古典经济学的Solow增长模型扩展为一个包含制度变量的计量经济学模型,并结合空间面板数据分析方法,使用1997—2005年中国省区的社会经济数据实证检验了经济制度环境对经济增长的影响。研究结果表明:该时期的制度变迁对中国的经济增长具有显著贡献力,证实了North的制度经济学理论假设。此外,空间面板数据的分析方法深入地揭示了省域经济活动之间存在的空间自相关性,即地区之间通过技术扩散、要素转移以及社会文化交流等在地理空间上发生相互影响。  相似文献   

城镇化、郊区化与中国城市空间扩张     

龙茂乾  孟晓晨 《地域研究与开发》2015,(3)

城市经济学的理论表明,城市人口增长和交通改善等因素都会导致城市的空间扩张,但其作用的机理不同。结合中国的情况,将城市空间扩张的影响因素分为城镇化和郊区化2个市场化动力,二者都会推动城市空间扩张,导致城市边界向外延伸。历年截面数据和面板数据分析结果都表明,在中国城市空间扩张进程中,城镇化动力和郊区化动力都在起作用,城镇化动力占主导地位,与此同时,郊区化动力也有增强的趋势。人口增长和交通改善推动城市空间扩张,城市建成区面积扩张的推动力远大于阻力。作为城市空间扩张速度变化的分水岭以及市场作用下收入水平显著性改变的分界点,1998年的住房制度改革对于中国城市空间扩张进程有着里程碑式的意义。  相似文献   

水力插板在海港工程中的应用     

刘爱霞  何富荣 《海岸工程》2010,29(3):74-78

水力插板技术具有安全稳定性高、施工速度快等优点,经过长期的现场试验逐步形成了水力插板与抛石防护相结合这样一种工程建设模式,将此项技术应用到海港工程中具有其特殊优势,值得推广应用。  相似文献   

A B-spline based higher order panel method for analysis of steady flow around marine propellers     

G.-D. Kim  C.-S. Lee  J.E. Kerwin 《Ocean Engineering》2007,34(14-15):2045-2060

A higher order panel method based on B-spline representation for both the geometry and the solution is developed for the analysis of steady flow around marine propellers. The self-influence functions due to the normal dipole and the source are desingularized through the quadratic transformation, and then shown to be evaluated using conventional numerical quadrature. By selecting a proper order for numerical quadrature, the accuracy of the present method can be increased to the machine limit. The far- and near-field influences are shown to be evaluated based on the same far-field approximation, but the near-field solution requires subdividing the panels into smaller subpanels continuously, which can be effectively implemented due to the B-spline representation of the geometry. A null pressure jump Kutta condition at the trailing edge is found to be effective in stabilizing the solution process and in predicting the correct solution. Numerical experiments indicate that the present method is robust and predicts the pressure distribution on the blade surface, including very close to the tip and trailing edge regions, with far fewer panels than existing low-order panel methods.  相似文献   

仿鱼尾潜器推进系统的水动力分析   总被引：21，自引：3，他引：21  

苏玉民  黄胜等 《海洋工程》2002,20(2):54-59

以开发适用于小型潜器的仿生操纵与推进系统为研究背景 ,对金枪鱼的月牙形尾鳍进行水动力分析。文中将金枪鱼的尾鳍处理为在做横移和摇摆的耦合运动的同时 ,以某一匀速向前运动的月牙形刚性尾翼。计算中应用了双曲面元和压力库塔条件 ,利用面元法计算分析该三维尾翼的非定常水动力性能。探讨了前进速度、横荡和摇首的幅度、频率及其相位差对推进性能的影响  相似文献   

Separating species using a horizontal panel in the Scottish North Sea whitefish trawl fishery     

Ferro  R. S. T.; Jones  E. G.; Kynoch  R. J.; Fryer  R. J.; Buckett  B-E. 《ICES Journal of Marine Science》2007,64(8):1543-1550

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Design of ship's bow form by potential-based panel method     

Jaehoon Yoo   《Ocean Engineering》2007,34(8-9):1089-1095

A surface panel method treating a boundary-value problem of the Dirichlet type with the free surface is presented to design a three-dimensional body corresponding to a prescribed pressure distribution. The free surface boundary condition is linearized with respect to the oncoming flow, and computed by four-point finite difference scheme. Sample designs for submerged spheroids and Wigley hull are carried out to demonstrate the stable convergence, the effectiveness and the robustness of the method. The design of a 5500TEU container carrier is performed with respect to reduction of the wave resistance. To reduce the wave resistance, calculated pressure on the hull surface is modified to have the lower fluctuation, and is applied as a Dirichlet type dynamic boundary condition on the hull surface. The designed hull form is verified to have the lower wave resistance than the initial one not only by computation but also by experiment.  相似文献   

Modelling the size selectivities of a trawl codend and an associated square mesh panel   总被引：8，自引：1，他引：8  

Zuur  G.; Fryer  R. J.; Ferro  R. S. T.; Tokai  T. 《ICES Journal of Marine Science》2001,58(3):657-671

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