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151.
The Moon 35 years after Apollo: What's left to learn?   总被引:1,自引:0,他引:1  
With the cancellation of the Apollo program after Apollo 17 returned from the Moon in 1972, the focus of NASA switched to other areas of the Solar System. Study of the Moon did continue through analysis of the returned samples and remotely sensed data sets (both orbital and surface), as well as through Earth-based telescopic studies. In the 1990s, new orbital data were obtained from several missions (fly-by and orbital), the first being Galileo that allowed the lunar farside to be mapped, followed by global mapping by the Clementine and Lunar Prospector missions.Interest in the Moon started to increase at the beginning of the 21st century as other nations focused their space exploration programs on the Moon. The speech by President Bush in January 2004 put the Moon back into the critical exploration path for NASA, paving the way for humans to return to the lunar surface by 2020. This return will be critical for developing technologies and protocols for the eventual human exploration of other parts of the solar system. At the time of writing (June 2008), the SELENE/Kaguya mission (Japan and Chang’e-1 (China) are orbiting the Moon, with Chandrayaan-1 (India) and Lunar Reconnaissance Orbiter (USA) being scheduled to launch later in 2008.The past (and present) exploration of the Moon begs the question “what's left to be done?” With the renewed focus on the Moon, now that it is on the pathway for the exploration of Mars (and beyond) a similar question has been raised - what should the astronauts do on the Moon? The publication of the New Views of the Moon book [Jolliff et al., 2006. New Views of the Moon, Reviews in Mineralogy, vol. 60. American Mineralogical Society, 721pp] highlighted a number of important scientific questions that remain unanswered as well as posing many more on the basis of the currently available data. These questions resonated in three Lunar Exploration Analysis Group (LEAG) reports pertinent to this discussion, which were also published (on line) during 2006 (http://www.lpi.usra.edu/leag), and in the National Research Council of the National Academies [2007. The Scientific Context for Exploration of the Moon. National Academies Press, Washington, DC, 112pp] report entitled “The Scientific Context for Exploration of the Moon”. This paper synthesizes these recent studies, along with those from the 1980s and 1990s, to emphasize the lunar science questions that remain unanswered. In addition, it summarizes the missions already flown to the Moon along with those that are planned in order to give the reader an idea of exactly what lunar science has been and will be conducted in the hope that it will inspire proposals for missions to address the outstanding science questions.  相似文献   
152.
Pyrometallurgical relics from smelting of iron as well as base metal ores are mineralogically and chemically investigated and dated using the radiocarbon method and optically stimulated luminescence. This study addresses the question whether these pyrometallurgical remains may be used as an exploration tool enabling geologists to discriminate between false and true gossans. Moreover, these investigations make a historical contribution and demonstrate how mining and smelting activities spread across NE Bavaria, Germany.  相似文献   
153.
大庆油田勘探50年:陆相生油理论的伟大实践   总被引:4,自引:0,他引:4       下载免费PDF全文
文章系统分析了陆相生油理论和大庆油田的勘探实践,总结了大庆油田的勘探历程并划分为三大阶段:构造油藏勘探阶段,岩性油藏勘探的探索阶段,岩性油藏勘探大发展阶段。详细阐述了“十五”以来,大庆油田依靠创新理论与技术,丰富完善了大型陆相坳陷盆地岩性油藏勘探理论与配套技术,深层火山岩气藏勘探理论与配套技术,复杂断陷盆地油气勘探理论与配套技术,从而带来了松辽盆地北部中一浅层、深层和海拉尔盆地油气勘探的大发展,大庆油田再次进入油气储量增长高峰期。在详细分析大庆探区的勘探实际和资源潜力的基础上,提出了“百年油田”勘探的工作思路,通过扎实推进科学勘探,努力为油田可持续发展提供有力资源保障的勘探战略。  相似文献   
154.
基于人文地理视角下的城市创意产业图像可视化分析对城市深层次空间综合和区域创新发展具有重大意义。但Swarm群智能动态时空建模难以满足创意产业空间集聚的可视化发展。本文研究目标是,从城市区域创意产业空间聚类影响因素指标出发,创新性地提出区域空间动态集聚轨迹算法(Density-Based Interest Spatial Clustering of Path,DBICP),并与计算机浏览器共建聚类可视化图像,为城市管理提供决策依据。首先,根据影响因素指标体系,利用2014—2018年空间卡口流量数据和产业指标数据进行预处理,构建空间标准聚类算法DBSCAN。然后,对其进行聚类密度分级优化形成全新DBICP算法并得出初步轨迹图像。最后,通过源码转译实现了浏览器界面下空间动态集聚轨迹图像的输出。结果表明:以上海市为例,普陀区、浦东新区、徐汇地区的创意产业空间分布形成了3种不同的聚类模式,并相应提出了分摊、均布、虹吸的管控策略。此方法克服了传统图像的聚类分级和轨迹测量的缺失,可以有效地从指标数据中发现图像轨迹聚类信息,体现了地理信息科学和人文社会学科的交叉融合。也为大数据动态图像的集聚方法提供了全新视角和借鉴价值。  相似文献   
155.
传统的缓存置换策略未充分考虑数据访问的空间特征,也不适用于基于矢量瓦片的替换。该文根据矢量瓦片的空间数据结构,提出一种适用于矢量瓦片缓存替换的视点相关预测区域算法:首先根据瓦片存储中多分辨率金字塔结构进行空间单元划分,并根据用户操作类型求解矢量瓦片及空间单元热度,从而构建用户视点位置相关的预测区域;然后综合考虑瓦片层级、空间单元热度及距离等因素进行预测区域分析,获得瓦片缓存价值并进行瓦片置换。通过与传统的FIFO、LRU和LFU缓存策略相比较,该算法的瓦片命中率比FIFO和LRU分别提高了近50%和20%,瓦片的请求耗时分别缩短了50%和30%左右,相比LFU也有明显优势。该研究为WebGIS提供了一种更具潜力的瓦片缓存方法。  相似文献   
156.
走向伟大复兴的中国地缘战略:国家周边论   总被引:1,自引:0,他引:1  
伴随批判地缘政治学的兴起,围绕古典地缘战略理论的争论一度成为学术研究的焦点,而“一带一路”倡议的提出更是激起有关“一带一路”是否是中国当前全球地缘战略的讨论。2019年新冠疫情叠加中美大脱钩使得中国适时调整和制定符合当前整体地缘环境态势的地缘战略迫在眉睫,这关系到“两个一百年”目标和民族复兴能否实现。本文借鉴哲学中的主体间性概念重新解读了古典的地缘战略理论。在归纳总结古典地缘战略理论所具有的固有特征后,反驳了“一带一路”倡议为中国地缘战略的观点。借用古典地缘战略隐含的构建方式,在分析全球地缘环境、中美地缘关系和中国地缘环境后,提出了到21世纪中叶前中国的地缘战略——国家周边论。但是,我们应该承认,无论对中国还是对美国而言,继续围绕中国周边地区的对抗甚至全球尺度的冲突对于双方甚至全球都是不利的。中美必须走出过去历史长河中形成的强国必霸的主体间性的共识,在对话、交流的基础上,实现中美互动实践的良性循环,以此结束当今世界的种种冲突,走向和平发展,构建人类命运共同体。  相似文献   
157.
研究《宁夏空间发展战略规划》的实施对策,对落实规划总体战略、促进宁夏协调发展具有重要的战略意义。实施"一主三副"战略,推进区域协调发展,重点破解区域发展中差别化不明显的问题;实施"两带两轴"战略,推进城乡协调发展,重点破解城乡二元结构问题;实施"产业集群"战略,推进经济社会协调发展,重点破解产业支撑能力弱的问题;实施"山河为脉"战略,推进人与自然协调发展,重点破解发展的粗放低效和资源约束问题;实施"内陆开放"战略,推进区内开发与对外开放协调发展,重点破解国内开放与国外开放程度较低的问题。  相似文献   
158.
During the last quarter-century, global demand for energy has increased by more than 60%, and a similar increase is anticipated to occur by 2030 (Raymond, Deming, & Nichols, 2007). In the U.S., oil and gas development is projected to continue across western states within sage-grouse habitat. Greater sage-grouse, recently a candidate species for protection under the Endangered Species Act (ESA), have well documented negative responses to oil and gas disturbance. In this study, we create spatially-explicit oil and gas future development scenarios, baseline and high, and link them to sage-grouse population and habitat maps to quantify future exposure risk within Western Association of Fish and Wildlife Agencies (WAFWA) sage-grouse management zones (MZ) I and II. We then analyze recent land use decisions from the Bureau of Land Management (BLM) along with enacted policy from the State of Wyoming to estimate how these management actions might minimize the exposure risk of sage-grouse to oil and gas development into the future. Our results show that BLM and Wyoming conservation plans could reduce the exposure of sage-grouse to oil and gas development from 15-27% to 11–17% (31–37% reduction) in MZ I and from 15-27% to 5–9% (64–68% reduction) in MZ II. Our estimates of exposure to future oil and gas development, and conservation measures designed to ameliorate those threats, represent the upper and lower extents of potential impacts within scenarios. Our work demonstrates how spatial modeling and GIS visualization can be used by managers to assess likely outcomes of conservation decisions.  相似文献   
159.
Sustainable management of communal grazing lands in Ethiopia is crucial to sustain livestock productivity and reduce land degradation. This study was conducted in Dera district, Ethiopia, to assess local communities’ perceptions of the degradation and their attitudes on the management of communal grazing lands. Household surveys, group discussions, and the contingent valuation method were used to gather data. Results indicated that local communities are aware of the degradation and are willing to participate in the management of communal grazing lands by contributing labor and cash. Labor contribution is positively and significantly correlated to total livestock units (TLU) and credit, and negatively correlated with household size and extension service. Significant correlation between the willingness to contribute cash and TLU was also detected. Community participation and discussions, demarcation of boundaries, equity in benefit sharing, and engaging both formal and informal institutions are crucial to sustain and enhance the effectiveness of grazing land management.  相似文献   
160.
The introduction of productive gardens on public building roofs is an active way to use urban idle space. It has ecological, economic, and social values and helps alleviate many urban problems caused by the rapid advancement of land urbanization. This paper takes the productive rooftop garden of an urban commercial complex as an example, and assesses its development status based on methods including ArcGIS, field research, and questionnaire interviews, combined with the overall aspects of the country and key case analysis. The results indicate several key aspects of the current status of such gardens in China. (1) As affected by natural and social factors, the current spatial distribution of productive rooftop gardens of commercial complexes in Chinese mainland is uneven, with 84.21% located in the southeast coast and the Sichuan region. (2) The operation and development of this type of productive landscape is in good shape. The number of rooftop gardens has continued to increase since 2013, and the scale is generally greater. Currently, the business model which combines nature education and parent-child amusement experience activities is the most stable. (3) Cases in good operating condition tend to have relatively related characteristics in layouts, traffic functions, landscape elements, and space design. (4) Questionnaire interviews show that citizens are highly willing to participate in rooftop productive landscapes, while operators still experience challenges in policies, funds, and planting knowledge in practice. This paper analyses the existing problems in the development status and strategy of the rooftop productive landscape. It proposes complementary optimization strategies to serve as a reference for the rooftop design of commercial complexes and the utilization of a significant amount of idle space on the roofs.  相似文献   
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