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891.
云会才  李启高 《北京测绘》2012,(4):49-51,78
阐述了极坐标法在山体边坡爆破测量中的应用。包括在杭甬高速公路拓宽工程中306标段施工边界线、坡顶线、坡底线和坡的开挖线的放样,炮孔深度的测算等。极坐标法在山体边坡爆破测量中对工程的施工既起到了保障和检校的作用,又起到了对工程施工降低成本费用的作用。  相似文献   
892.
分析了运河船闸检修期变形监测的必要性和紧迫性,研究了船闸变形监测控制网与监测点的布设方法,并讨论了监测周期和精度的确定方法。工程应用表明,该种监测方法有效可靠,对类似工程具有一定的借鉴意义。  相似文献   
893.
海洋石油支持船的船舶特性及其作业任务的特殊性,决定了不能照搬照抄航运企业的经验,必须探索出一条自己的节能减排路径.在分析各种影响船舶油耗的因素的基础上,筛选出海洋石油支持船节油空间较大以及可控的影响因素,提出节能减排的实施思路.  相似文献   
894.
波浪作用下带月池结构船体运动数值预报   总被引:2,自引:0,他引:2  
流体在月池内发生共振时,有可能给船舶带来多种危险。建立基于N-S方程和VOF法的三维数值波浪水池,通过实现船体与波浪的耦合运动,对月池内流体发生活塞运动共振情况下的船体运动做出了数值预报,研究了船体运动和月池内流体运动的相互影响。通过与无月池结构船体运动对比,得到了共振情况下月池内流体活塞运动会增大船体垂荡运动的结论;通过与船体静止情况下月池内流体运动的对比,得到了船体运动会增大月池内流体活塞运动的结论。另外还研究了月池内的流场变化,以研究月池振荡的机理。  相似文献   
895.
This study takes cognizance of the fact that the TIOMIN (TIOMIN Resources Inc. of Canada) project has resulted in controversy over its handling of environmental issues and especially the Environmental Impact Assessment (EIA). The authors address many of the protracted issues that have slowed the development of the mining project in Kwale. The main emphasis is on the impacts of the mining and mineral separation processes on the environment, including the governing legislation, the role of consultation and public participation, and socioeconomic issues. In their public documents TIOMIN has specified neither the type of minerals it wants to extract from the area nor their chemical composition. It is well known, however that the titanium minerals and zircon targeted have impurities of iron, thorium and uranium. In the absence of an Environmental Management Plan, the effects of stockpiling radioactive wastes and other impurities that could possibly lead to environmental degradation in both the terrestrial and marine environments have not been publically addressed. The measures proposed to mitigate ecological damage as a result of the establishment of a minerals processing plant in the area seem inadequate. Pollution resulting from accidental spillage or breakage could have significant impact on marine life and residents living near the mining site. Other issues that have not been addressed satisfactorily pertain to the use of surface and underground water. The area already faces a huge water deficit and the calculations presented on aquifer recharge and stream flow rates do not indicate the large quantities of water that would be required in the mineral processing plant. The project, if approved in its present state, risks violation of international conventions. Furthermore, it could cause a conflict between Kenya and Tanzania in the event of an oil spill at the proposed ship loading facility at Shimoni. The proposed mining area includes the district's most fertile land, is home to many fisherfolk and is a major tourist destination. An analysis of the effects of this project on other available opportunities must be thoroughly understood to ascertain the economic and environmental benefits and costs of the mining venture. The proposed compensation rate of $1,000 per acre, for resettlement for example, appears to be grossly inadequate. Compensation should take into account family size and structure family assets and the cost of relocation.  相似文献   
896.
A fretted valley system on Mars located at the northern mid-latitude dichotomy boundary contains lineated valley fill (LVF) with extensive flow-like features interpreted to be glacial in origin. We have modeled this deposit using glacial flow models linked to atmospheric general circulation models (GCM) for conditions consistent with the deposition of snow and ice in amounts sufficient to explain the interpreted glaciation. In the first glacial flow model simulation, sources were modeled in the alcoves only and were found to be consistent with the alpine valley glaciation interpretation for various environments of flow in the system. These results supported the interpretation of the observed LVF deposits as resulting from initial ice accumulation in the alcoves, accompanied by debris cover that led to advancing alpine glacial landsystems to the extent observed today, with preservation of their flow texture and the underlying ice during downwasting in the waning stages of glaciation. In the second glacial flow model simulation, the regional accumulation patterns predicted by a GCM linked to simulation of a glacial period were used. This glacial flow model simulation produced a much wider region of thick ice accumulation, and significant glaciation on the plateaus and in the regional plains surrounding the dichotomy boundary. Deglaciation produced decreasing ice thicknesses, with flow centered on the fretted valleys. As plateaus lost ice, scarps and cliffs of the valley and dichotomy boundary walls were exposed, providing considerable potential for the production of a rock debris cover that could preserve the underlying ice and the surface flow patterns seen today. In this model, the lineated valley fill and lobate debris aprons were the product of final retreat and downwasting of a much larger, regional glacial landsystem, rather than representing the maximum extent of an alpine valley glacial landsystem. These results favor the interpretation that periods of mid-latitude glaciation were characterized by extensive plateau and plains ice cover, rather than being restricted to alcoves and adjacent valleys, and that the observed lineated valley fill and lobate debris aprons represent debris-covered residual remnants of a once more extensive glaciation.  相似文献   
897.
王慧  刘涛  尹尽勇 《气象科技》2009,37(4):503-507
利用多个卫星高度计融合资料,分析了南海冬季(1月)3年(2006~2008年)平均的风场特征和海况条件。结果显示:南海东北部和台湾海峡、巴士海峡的风力和浪高都最大,其次是南海西南部海域的风力和浪高较大,其余海域的风力和浪高较小。根据这些特点,从船舶航行的安全性和经济性上考虑,设计了南海冬季北行的4条航线:从马六甲海峡直接行驶到台湾海峡的最短航线、躲避南海西南部大风大浪区和台湾以南的大浪区的航线、躲避台湾海峡的大风而绕行台湾以东的航线以及比较安全但是航线很长的航线。船长可以根据南海冬季大风大浪的情况选择避风航行的最佳航线。H轮在2005年1月行驶到南海时躲避大风大浪的实例说明大风大浪对船舶安全性的影响非常显著。  相似文献   
898.
南半球10 hPa极地涡旋的多尺度变化特征分析   总被引:1,自引:1,他引:0       下载免费PDF全文
利用NCEP/NCAR 10 hPa月平均高度场资料, 计算了1948\_2007年南半球10 hPa极地涡旋的强度指数P、 面积指数S和中心位置指数(λc, φc)。用它们分析了南半球10 hPa极地涡旋的季节变化、 年际异常及其可能成因, 分析了10 hPa极地涡旋强度与南极涛动的关系。结果表明: (1) 南半球10 hPa极区12月~1月受反气旋控制, 3~10月受气旋控制, 2月、 11月为环流转换季节。(2) 1(7)月反气旋(气旋)指数P\, S均在1970年代后期发生了显著的跃变; 跃变前反气旋(气旋)由极弱(极强)振荡地增强(减弱)至接近气候均值, 跃变后反气旋由极强振荡趋于气候均值, 气旋在偏弱的状态下振荡。(3) 1月反气旋中心位置存在显著的年代际变化, 而7月气旋中心位置的年际变化明显。(4) 臭氧异常可引起南半球10 hPa 1月极地反气旋年际异常(正相关), 但与7月极地气旋异常无关。(5) 1月、 7月极地涡旋强度指数P与南极涛动指数(AAOI)呈显著的负相关, 可由P来表征AAOI。  相似文献   
899.
David Horne  Michael D. Smith 《Icarus》2009,200(1):118-128
The Mars Global Surveyor Thermal Emission Spectrometer (TES) instrument has returned over 200 million thermal infrared spectra of Mars taken between March 1999 and August 2004. This represents one of the most complete records of spatial and temporal changes of the martian atmosphere ever recorded by an orbiting spacecraft. Previous reports of the standard TES retrieval of aerosol optical depth have been limited to those observations taken over surfaces with temperatures above 210 K, limiting the spatiotemporal coverage of Polar Regions with TES. Here, we present an extension to the standard TES retrieval that better models the effects of cold surfaces below 200 K. This modification allows aerosol optical depth to be retrieved from TES spectra over a greater spatiotemporal range than was previously possible, specifically in Polar Regions. This new algorithm is applied to the Polar Regions to show the seasonal variability in dust and ice optical depth for the complete temporal range of the TES database (Mars Year 24, Ls=104°, 1 March 1999 to Mars Year 24, Ls=82°, 31 August 2004).  相似文献   
900.
Polar regions on Mars are the most suitable places to observe water vapor daily variability because in any observation crossing the Pole we can observe very different local time and because the poles are considered to be the main permanent and seasonal water reservoir of the planet. We report on a daily variability of water vapor in the South Pole Region (SPR), observed by OMEGA/Mars Express during the south spring-summer period (Ls∼250°-270°) outside the CO2 ice cap, that has never been observed before by other instruments. We have been able to estimate an increase of few precipitable microns during the day. A possible scenario includes the presence of regolith, or another component that could gather water from the atmosphere, adsorbing the water into the surface during the night time and desorbing it as soon as the Sun reaches sufficient height to heat the ground. This hypothesis is even more plausible considering the presence of observed local enhancements in the morning sections associated with the illumination of the Sun and the total absence in the data for water ice.  相似文献   
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