关于金属矿床深部找矿关键技术发展战略的思考

把已知矿床的深部、覆盖区的找矿皆纳入深部矿找矿的范畴。由于传统方法和思路对深部找矿难以奏效,迫切需要研究和开发新理论、新方法和新技术。当前,深部矿产勘查正处在建立新一代地质勘查技术体系的关键时期,新技术体系的显著特点是以信息技术为核心,加大探测深度,加强综合集成,增强快捷有效。金属矿床深部找矿关键技术发展的战略方针是：优先实用性,突出原创性,推动集成性,提高总效益。重视加强技术创新、技术集成、技术引进和消化,实现中央与地方、政府与企业、公益性地质调查与商业性矿产勘查互动,提高对成矿区（带）深部调查的能力、对深部矿床预测选区的能力、对深部矿床发现和矿床（体）定位的能力,增强多种技术融合的能力,促进 “速度引进型”技术发展战略转向“效益创新型”技术发展战略。据此,在征求广大专家意见的基础上筛选出了20项深部找矿关键技术领域。     

北京城市增长边界预测

为了遏制北京”摊大饼”式的城市发展模式,促进土地资源的集约、高效利用,引导国土空间合理布局,划定北京城市增长边界成为重要举措。本研究从城市内生发展动力角度,将遗传神经网络嵌入CA模型,建立北京城市增长边界预测模型,选定了自然、人口经济、区位、邻域、土地利用类型和政策规划6类因素共18个影响因子,预测北京市城市增长弹性边界。同时,从土地自身生态承载能力角度,用建设用地适宜性评价方法,选定了地形、地貌、公园水域、土地利用现状、自然保护区、城市用地距离为影响因子,划定北京市城市增长刚性边界。结果表明,利用该模型预测北京市2025年城市增长边界,总的面积匹配值为96%,模型精度较高;2025年北京市弹性增长边界总面积为1738.98 km²,刚性增长边界总面积为3297.01 km²。基于GANN-CA模型的城市增长边界划定方法对确定城市未来扩张方向有指导作用,可为城市规划和发展政策的制定提供依据。     

“数字城市”及其关键技术

“数字地球”是一个可以嵌入海量地理数据的、多分辨率的、真实地球的三维表示。自美国前副总统戈尔提出“数字地球”概念以来 ,世界上许多国家都在探讨如何实施本国的“数字地球”战略 ,力争在当今科技制高点上占据一席之地。在实施“数字地球”战略时 ,作为地球表面人口、资源、环境、信息最密集的地区 ,城市必然成为主要切入点之一。“数字城市”研究是当前地理信息科学研究的一个热点。与“数字地球”不同 ,“数字城市”是在城市数字化基础上建立的一个能够实现城市综合管理与决策支持的、虚拟的、具有开放性的城市模型。     

Ellipticity corrections for seismic phases

The advent of broad-band seismology has meant that use is being made of a wide range of seismic phases, for many of which ellipticity corrections have not been readily available. In particular, when many seismic phases are used in location schemes, it is important that the systematic effects of ellipticity are included for each phase.
An efficient and effective procedure for constructing ellipticity corrections is to make use of the ray-based approach of Dziewonksi & Gilbert (1976), as reformulated by Doornbos (1988), in conjunction with the rapid evaluation of traveltimes and slownesses for a given range using the tauspline procedure of Buland & Chapman (1983).
Ellipticity coefficients have been tabulated for a wide range of seismic phases and are available in electronic form. The ellipticity correction procedures have been extended to include an allowance for diffraction phenomena, for example P _diff, S _diff diffracted along the core-mantle boundary. Corrections for additional phases can be generated by building the ellipticity coefficients from suitable combinations of the coefficients for different phase segments.     

Regional Comparisons of Metropolitan and Nonmetropolitan Migration in the 1970s and 1980s: Age and Place Implications*

Over the last thirty years, nonmetropolitan regions across the United States have experienced volatile population shifts ranging from rapid growth to persistent decline. Several authors have suggested that the age structure of the population may contribute to these population trends. In the 1970s, the older baby boomers were entering labor and housing markets, while the younger boomers were enrolling in nonmetropolitan colleges and universities. By the 1980s, this large cohort was aging into a different stage in the life course. This article examines metropolitan and nonmetropolitan population shifts during the 1970s and 1980s within an age‐cohort framework. Using Public Use Microsample data from 1980 and 1990, the analysis explores relationships between housing market, labor market, place characteristics, and the migration flows of different age cohorts. The analysis focuses on cohort‐specific in‐migration to two regions: New England and the Four Corners states of Utah, Colorado, Arizona, and New Mexico. The results are consistent with a life‐course understanding of migration behavior, especially during the late 1970s, with older cohort shifts directed towards nonmetropolitan destinations and younger cohort shifts more influenced by labor and housing‐market variables. The results further demonstrate a large potential for future nonmetropolitan population growth, yet these growth experiences are likely to be regionally differentiated. These results have important policy implications for nonmetropolitan regions.     

一种特殊的实时图象处理—图环图象展开

作者在文中给出了一种将圆环域图象展开成矩形图象的方法，这种方法主要采用八分之一圆扫描方法，快速找出某个圆的所有象素，然后通过双线性插值或抽值将其变为展开图中对应的象素。