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481.
根据施工的实践,用CASIO-4800P计算器编制出一个程序,在采用全站仪任意点坐标法放样时,计算出待求点的坐标。达到放样多个单交点平曲线道路中、边桩的简便计算目的。 相似文献
482.
483.
研究基于某地铁停车场出入段线基坑支护方案的优化设计,利用比选排除法得出适合该研究区基坑支护方案并对每个方案进行支护设计,进而利用数学模糊评判方法对所有适用方案进行综合评分,选出最优方案。对基坑设计进行验算,ADINA软件进行模拟,验证了最终方案的可行性,对基坑支护方案选型及设计有一定的参考意义。 相似文献
484.
岩浆的分离结晶作用和地壳同化混染作用是造成硫饱和的重要因素。本文以金平-Song Da地区二叠纪低钛苦橄岩为原生岩浆,使用MELTS程序模拟了岩浆在分离结晶和围岩同化混染作用的控制下达到硫饱和,发生硫化物熔体的熔离。模拟结果表明,低钛苦橄质岩浆从源区上升到浅部岩浆房的过程中发生了约10%的橄榄石的分离结晶,形成高镁的玄武质岩浆。高镁玄武质岩浆在浅部岩浆房内同化混染>18%的围岩,并经历约27%硅酸盐矿物的分离结晶后达到硫饱和。熔离的硫化物熔体在岩浆通道内聚集形成了白马寨铜镍硫化物矿。经历硫化物熔体熔离后的残余岩浆喷出地表形成了金平地区亏损Ni和Cu并具有强烈地壳混染特征的低钛玄武岩。 相似文献
485.
将3维GIS引入到建设方案的分析与审查过程中,通过建立真实的3维场景,将建设方案纳入到3维场景中,借助GIS的空间分析工具,从不同的角度和视点对建设方案进行了分析,模拟了不同建设方案建成后对周围景观的影响,从而有力地支撑了方案的审查。 相似文献
486.
对林业地理实体时空演变过程进行分析,认为林业地理实体的演变总体上是渐变和突变交替的时空过程,而且各专题属性和空间分布的演变类型和演变频率不尽相同。在此基础上,提出由序列快照和事件方法组合而成的序列状态时空表达方法,以状态集表达时空对象在生命周期内的演化历程,并针对林业数据的特点,采用面向对象的数据组织方式设计了林业资源时空数据模型。模型可对不同演变类型进行组合,并实现了对渐变和突变的统一表达,另外,模型也允许采用不确定数据以加强对渐变过程的表达。通过原型系统验证了模型的可行性。 相似文献
487.
488.
This paper presents a substructure online hybrid test system that is extensible for geographically distributed tests.This system consists of a set of devices conventionally used for cyclic tests to load the tested substructures onto the target displacement or the target force.Due to their robustness and portability,individual sets of conventional loading devices can be transported and reconfigured to realize physical loading in geographically remote laboratories.Another appealing feature is the flexible displacement-force mixed control that is particularly suitable for specimens having large disparities in stiffness during various performance stages.To conduct a substructure online hybrid test,an extensible framework is developed,which is equipped with a generalized interface to encapsulate each substructure.Multiple tested substructures and analyzed substructures using various structural program codes can be accommodated within the single framework,simply interfaced with the boundary displacements and forces.A coordinator program is developed to keep the boundaries among all substructures compatible and equilibrated.An Internet-based data exchange scheme is also devised to transfer data among computers equipped with different software environments.A series of online hybrid tests are introduced,and the portability,flexibility,and extensibility of the online hybrid test system are demonstrated. 相似文献
489.
Rural governance has drawn considerable attention from both local government officials and scholars in the United States since the early 1990s. It is touted as a way to mitigate the limitations of the traditional government unit‐based approaches to problem solving and decision making and to foster partnerships across both jurisdictional boundaries and sectors (public, private, and nonprofit). Established in 1962, the Resource Conservation and Development (rc&d ) program of the U.S. Department of Agriculture provides a unique model of rural regional governance. Acting as a coalition of governments, private businesses, individuals, and interest groups, the rc&d program provides the flexibility needed to deal with issues at the appropriate spatial scale. It incorporates aspects of both grassroots and governmental organizations and can bring together local interests and expertise with governmental policy and support in service provision, problem solving, and economic development. The approach does not necessarily entail loss of power on the part of the state, but it does provide a mechanism for local people to exercise their agency, to tackle their problems, and to decide which elements of their lives they want to sustain. 相似文献
490.
《The Professional geographer》2013,65(3):271-277
The concentration of poor, service-dependent groups in aging central cities results both from suburbanization of the affluent and from the reliance of the service-dependent population upon place-specific human services provided by the public sector. Such concentration of services and their users in deteriorating inner-city sites may be functional for the larger society, but it has adverse impacts upon those who are service dependent. This paper argues that the implications of locational interdependence between such groups and their support services demand a paradigm for urban geography that centers upon the fundamental structure and impacts of population/service-provision linkages. 相似文献