执行2009版《全球定位系统(GPS)测量规范》若干问题的研究

结合技术人员在执行《全球定位系统(GPS)测量规范》(GB/T18314—2009)时的不同理解和认识,通过对基线测量中误差、环闭合差、相邻点基线分量中误差和GPS网平差技术指标等的计算与实现,进行了理论分析和实践探讨,得出规范可以得到较好执行的结论。     

不同分布模式电离层对星载InSAR测高精度的影响及校正

电离层总电子含量(TEC)会使合成孔径雷达干涉测量(In SAR)信号产生相位延迟,进而影响生成DEM的精度,特别是对L和P等长波段信号的影响不可忽略。因此,针对不同TEC分布模式的电离层开展研究,构建了电离层对星载In SAR测高精度的影响模型,提出了相应的校正方法,并进行了仿真实验。实验表明对于特定波长的In SAR信号,不同TEC分布模式对In SAR测高精度的影响不同:TEC均匀分布的电离层模型对In SAR测高精度的影响较小,并可通过相位解缠、基线估计等环节进行很好的补偿;而TEC不均匀分布的电离层模型对In SAR精度的影响较大,仅靠相位解缠等过程不能较好地消除,必须通过向干涉图中加入电离层影响模型予以纠正。     

基于SBAS时序分析的大同地面沉降与地下水活动研究

大同盆地是汾渭盆地北端一个地面沉降较严重的区域,地下水开采是该区域地面沉降发生的一个重要原因。然而地下水活动与地面沉降在空间和时间的相关性却鲜有研究。为了掌握该地区地下水活动与地面沉降的内在联系,该文基于Envisat ASAR数据,利用短基线集(small baseline subset,SBAS)-In SAR技术对大同盆地地面沉降形变特征进行监测;同时利用地下水位监测数据,研究地面沉降中心与地下水位漏斗在空间和时间上的对应关系,定量分析2处地下水位波动与地表形变的关系。研究表明,地下水开采是大同盆地水源地地面沉降的主要原因,但并非所有的地下水位漏斗都存在地面沉降。该研究成果对指导该地区地下水开采及控制地面沉降有一定参考价值。     

基于DEM-CFD耦合的气吸式排种器仿真研究

为提高大白菜等小粒径精密播种机的机械化水平,设计了一种小粒径气吸式排种器.首先利用JPS-12排种器性能检测试验台对排种器进行测试,得到不同参数组合下的性能指标与最优参数组合.然后使用计算流体力学方法（CFD）,借助FLUENT软件分析了吸种器内部流场的分布,得到了吸种器内部压力分布云图和吸种孔截面云图.最后基于离散元法（DEM）建立大白菜种子颗粒模型,对排种器仿真模型进行简化和网格划分,完成了小粒径气吸式排种器DEM-CFD耦合仿真实验.对比台架与仿真试验结果,得出如下的结论：当排种盘转速为20 r/min,真空度为2.2 kPa时,排种性能最佳.     

Standardization of baseline and additionality determination under the CDM

Clean Development Mechanism (CDM) project developers have long complained about the complexities of project-specific baseline setting and the vagaries of additionality determination. In response to this, the CDM Executive Board took bold steps towards the standardization of CDM methodologies, culminating in the approval of guidelines for the establishment of performance standards in November 2011. The guidelines specify a performance standard stringency level for both baseline and additionality of 80% for several priority sectors and 90% for all other sectors. However, an analysis of 14 large-scale CDM methodologies that use performance standard approaches challenges this top-down approach to the performance standard design. An appropriate performance standard stringency level strongly depends on sector and technology characteristics. A single stringency level for baseline and additionality determination is appropriate only for greenfield projects, but not for retrofit ones. Overly simple, highly aggregated performance standards are unlikely to ensure high environmental integrity, and difficult questions regarding stringency and updating frequency will eventually have to be addressed on a rather disaggregated level. A careful balance between data requirements and the practicability of performance standards is essential because the heavy data requirements of the existing performance standard methodologies have been the key barrier to their actual implementation.

Policy relevance

CDM regulators have been pushed by many stakeholders to standardize baseline setting and eliminate project-specific additionality determination. At first glance, performance standards seem to provide the perfect solution for both tasks. However, a one-size-fits-all political decision – e.g. the average of the top 20% performers as enshrined in the Marrakech Accords – is inappropriate. Substantial disaggregation of performance standards is required both technologically and geographically in order to limit over- and under-crediting and close loopholes for non-additional projects. As a lack of reliable and complete data has been and will be a key bottleneck for the development of performance standards, international support for data collection will be indispensable, but costly, and time-consuming. Empirically driven, techno-economic assessments of performance standard stringency levels must be the central task of the future work on standardized methodologies, and should not be sidelined by perceived needs of policy makers to take bold decisions under time pressures.     

BOOK REVIEWS

Books reviewed in this article: Aerial Photography and Remote Sensing. Terrain Analysis and Remote Sensing . JOHN R. G. TOWNSHEND , ed. Environmental Data Use in Computer-assisted Data Handling Systems: The Results of a Survey of Applications in the Pacific Northwest States . KENNETH E. GORDON . Applied Land Use: A Spatial Approach . JOHN F. LOUNSBURY , LAWRENCE M. SOMMERS , AND EDWARD A. FERNALD , eds. The Second Battle of New Orleans: A History of the Vieux Carre Riverfront-Expressway Controversy . RICHARD O. BAUMBACH , JR. AND WILLIAM E. BORAH . Cultural Environmental Archaeology . MYRA SHACKLEY . The Immoral landscape: Female Prostitution in Western Societies . RICHARD SYMANSKI . life Among the Poor in Cairo . UNNI WIKAN , translated by Ann Henning. Women, Work and Property in Northwest India . URSULA SHARMA . The Domestication of Women: Discrimination in Developing Societies . BARBARA ROGERS Economic Optimization in Locational and Transport Analysis . A. G. WILSON , J. D. COELHO , S. M. MACGILL , H. C. W. L. WILLIAMS . New Tools for Economic Development: The Enterprise Zone, Development Bank, and RFC . GEORGE STERNLIEB AND DAVID LISTOKIN , eds. Regional Wage Inflation . R. L. MARTIN , ed. Finding A Place For Energy-Siting Coal Conversion Facilities . FRANK J. CALZONETTI WITH MARK S. ECKERT . Environmental Management, Resources, and Systems Environmentalism. Second Edition . T. O'RIORDAN . Countryside Conservation . BRYN GREEN . Medical Spatial Diffusion: An Historical Geography of Epidemics in an Island Community . A. D. CLIFF , P. HAGGETT , J. K. ORD , AND G. R. VERSEY . Philosophy and Geographic Thought Order and Skepticism: Human Geography and the Dialectic of Science . RICHARD SZYMANSKI AND JOHN A. AGNEW . Measurement of Subjective Phenomena . D. F. JOHNSTON , ed. Conceptions of Space in Social Thought: A Geographic Perspective . ROBERT DAVID SACK . The Association of American Geographers: The First Seventy-five Years: 1904-1979 . PRESTON E. JAMES AND GEOFFREY J. MARTIN . The Life and Thought of Isaiah Bowman . GEOFFREY J. MARTIN . Physical River Basin Planning: Theory and Practice . SURANJIT K. SAHA AND CHRISTOPHER J. BARROW , eds. Soils and landforms: An Integration of Ceomorphology and Pedology . A. I. GERRARD Climatic Change and Society. Consequences of Increasing Atmospheric Carbon Dioxide . WILLIAM W. KELLOGG AND ROBERT SCHWARE . Political Political Redistrictings and Geographic Theory . RICHARD L. MORRILL . Population Studies in Spanish American Population History: Dell Plain Latin American Studies NO. 8 . DAVID J. ROBINSON , ed. Population Redistribution in the Midwest . CURTIS C. ROSEMAN , ANDREW J. SOFRANKO , AND JAMES D. WILLIAMS , eds. Geographical Perspectives on the Elderly . A. M. WARNES , ed. Regional Perspective On the American South . MERLE BLACK AND JOHN SHELTON REED , eds. The Prairies and Plains: Prospects for the 80s . JOHN R. ROGGE , ed. Rural Rural Settlement in an Urban World . MICHAEL BUNCE . Social Accident at Three Mile Island: The Human Dimensions . DAVID L. SILLS , C. P. WOLF , AND VIVIEN B. SHELANSKI , eds. The American Small Town: Twentieth-Century Place Images . JOHN JAKLE . Urban A House of My Own . SUSAN LOBO . The City: Patterns and Processes in the Urban Ecosystem . CHRISTOPHER H. EXLINE , GARY L. PETERS , AND ROBERT P. LARKIN . Movement in Cities . P. W. DANIELS AND A. M. WARNES . Urbanization and Urban Planning in Capitalist Society . MICHAEL DEAR AND ALLEN J. SCOT , eds.     

一种快速获取GPS控制网精确WGS-84坐标方法

详细介绍了一种快速求取GPS控制网的精确WGS-84坐标的方法。首先选择三个天空通视条件较好、分布合理的控制网点,与附近的IGS跟踪站进行长基线相对定位或者直接进行静态精密单点定位,求得三点精确的WGS-84坐标,然后将这三个点作为已知点在WGS-84坐标系下进行三维约束平差,可求得控制网其它点精确的WGS-84坐标,这样求得网点的WGS-84坐标具有厘米级精度。     

小区域景观的三维可视化

现实世界的复杂性决定了其在计算机中表达的复杂性,三维模型的构建成为3DGIS中亟待解决的一个核心问题。探讨了三维建模思想以及建模方法,并以ArcGIS和SketchUp交互建模方法为例,论述了三维建模流程以及注意事项,通过模型库的构建,提高了该方法在小区域内景观的三维快速构建效率,所得的模型为3DGIS提供了数据源。实践表明,在有限的经济、技术等条件下,该方法具有较强的可行性和实用性。     

Excel在GPS基线解算精度统计中的应用

GPS基线解算就是利用GPS观测值,通过数据处理,得到测站间的基线向量值。基线解算是GPS网平差的基础和关键,基线解算精度直接关系着GPS网的精度,所以,基线解算精度统计是一项很有必要的工作。Excel中大量的公式函数可以应用选择,主要用来进行有繁重计算任务的预算、财务、数据处理等工作,借助于Excel的数据筛选和条件格式功能,可以方便、高效、准确无误地进行GPS精度统计,这在GPS广泛大量使用的今天,有一定的现实意义。