西秦岭温泉混浆花岗岩的微量与稀土元素地球化学特征

西秦岭温泉岩体是壳、幔岩浆混浆的产物。寄主岩石高Mo、Sn、Bi、W等高温热液成矿元素及Co、Ni、Cr等亲铁元素。而基性端元的暗色微细粒镁铁质包体及基性岩墙则异常富集轻稀土和Ba、Rb、Sr、Zr、Th、Hf、Nb等大离子亲石元素，贫Co、Ni、Cr等亲铁元素，微量元素的反常分布，指示了两个端元元素演化的显著依从性和交换性。LREE／HREE值在寄主岩石中为10～15，受岩浆混合作用影响在基性端元为9．98～13．5，异常富轻稀土。δEu值及(La／Sm)N、(Gd／Yb)N、(La／Yb)N等比值，显示该岩体为混浆花岗岩。岩浆混合作用强烈的混浆暗色花岗岩具有显著的壳慢过渡性质。     

Pore Fractal Dimensions of Bituminous Coal Reservoirs in North China and Their Impact on Gas Adsorption Capacity

Natural Resources Research - Coal pores not only serve as the storage space for coalbed methane but also provide channels for gas migration. The accurate characterization of coal pore structures is...     

基于均一化资料的西安极端气温变化特征研究

基于1960~2015年西安气象站点逐日最高温、最低温数据,采用RHtest软件对非均一化气温序列进行订正,进而选取16项极端气温指数,对西安极端气温变化特征进行分析。结果表明：① 由于气象站点迁移,西安气温资料存在非均一性,导致极端气温变化趋势被低估;② 全球变暖背景下,西安极端气温变化表现出：“快速增温与平稳波动并存,冷暖变化趋势相反,夜晚增暖趋势比白天明显,白天波动变化明显于夜晚,持续性高温事件变化不大,持续性低温事件大幅下降”的变化特征;③ 通过不同区域趋势变化对比、冷暖、昼夜变化关系对比发现,受城市热岛影响,西安极端低温事件减少更为突出,远高于中国其他对比区域（秦岭南北、黄土高原、东北地区等）;④ 在昼夜变化上,西安极端气温变化与中国、全球变化具有一致性,但是通过冷暖指标对比发现,西安极端气温变化具有区域性,表现为冷昼日数下降高于暖昼日数上升,冷夜日数下降高于暖夜日数上升,冷持续日数和暖持续日数共同表现为下降趋势。     

浙江陆路交通对区域旅游空间结构及发展的影响研究

基于加权平均出行时间、“板块旅游”空间结构理论、空间计量模型等方法,探讨1996~2016年浙江陆路交通对区域旅游空间结构及发展影响。研究表明：① 交通路网建设带来城市可达性提升,其地理过程、格局呈现围绕“四大都市区”轴带放射状“Π型”演变特征。② 交通网络效应下,新增景区密集分布于邻近中心城市主要对外交通要道两侧,耦合于可达性时空演变,且“板块”旅游地域结构特征显著。③ 空间计量结果发现,交通区位、经济基础、资源禀赋等因素不同程度影响地域旅游经济发展。     

辽东半岛的环境地质问题与防治对策研究

辽东半岛集中了辽宁省90%的大中型骨干企业、近70%的城市人口和固定资产,创造了辽宁省85%的经济总量,是辽宁省经济发展的龙头地带.本文根据辽东半岛地区地质环境背景条件,研究了不同地区、不同工程活动的环境地质问题,分析了其发育规律与特征,提出了防治环境地质问题的4条举措,即合理开采地下水,可持续利用地区水资源;采取工程...     

鲁西南大气降水与农田需水的供求状况及变化趋势

应用彭曼(Penman)法,并考虑对不同作物发育阶段的订正,估算了鲁西南地区的农田需水量。通过农田需水量与有效降水量差值分析,对二者的供求状况进行了评估。同时还分析了1961～2002年降水量和农田需水量的历史资料序列,发现二者都呈递减趋势,且递减的速度较为接近。     

Vulnerability of reinforced concrete frames in low seismic region,when designed according to BS 8110

The overstrength and ductility due to redistribution of internal forces are being investigated for three bay multi-storey reinforced concrete plane frames, using non-linear push-over analysis. These frames are designed to resist gravity loads, wind loads and a notional horizontal load in accordance with the British code BS 8110, which does not have any special provision for seismic loads. The results show that the overstrength factors for the three-, six- and ten-storey frames are respectively, 7·5, 5·6 and 2·2 times the design lateral loads, whereas, the ductility factors for the three frames are similar, and slightly greater than 2. These values yield a response modification factor of 18·0, 12·2 and 4·7 for the three-, six- and ten-storey frames, respectively. The effect of infill walls on the response modification factor is also being investigated, and a suitable response modification factor for assessing the vulnerability of reinforced concrete frames of about 10 storeys high is recommended. Copyright © 1999 John Wiley & Sons, Ltd.     

干冷空气活动对2008年梅雨降水的作用

利用NCEP/NCAR再分析资料,分析了2008年梅汛期暴雨过程中干冷空气侵入对暴雨发生、发展和维持的作用.结果表明:梅雨期中高纬度环流的演变和调整与暴雨过程密切相关,亚洲北部阻塞高压(高压脊)的建立和维持,使得500hPa高度上西风锋区南压,导致干冷空气南下,极涡活动的异常偏东和加强有助于冷空气向江淮流域输送,有利于江淮流域暴雨的发展.在江淮流域梅雨期间,干冷空气的活跃与暴雨过程相对应.干冷空气来源于中高纬度和中高层.干冷空气侵入有利于对流层中高层干层的形成和维持.而且,干冷空气侵入是梅雨湿度锋形成和维持的一个重要动力和热力原因.在此研究基础上,归纳出中期预报着眼点,供实际业务预报参考使用.     

基于数字高程模型的水系自动生成

为从数字高程模型(DEM)中自动提取区域水流特征,分析了DEM中地形的形态特征,并进行洼地填充和平地抬升的预处理,应用坡面流模拟方法进行了水流方向的确定及水流方向数字阵列的生成,最后根据水流方向阵列和河流栅格网络图生成需要的水系,其结果与手工数字化的水系基本一致,证明该方法是有效的。     

A center-based modeling approach to solve the districting problem

This article deals with the districting problem arising in applications such as political districting, police patrol area delineation and sales territory design. The aim of districting is to group basic areal units into geographic districts such that some set of criteria are satisfied, with basic criteria being district balance, compactness and contiguity. This article proposes a center-based mixed-integer linear programming model to solve the districting problem. Given the central units of districts, the model optimizes weighted objectives of district balance and compactness while satisfying contiguous constraints on districts. The performance of the model was tested using three study areas with 297, 324 and 1297 areal units, respectively. Experimentation shows that, using the district centers identified by a multistart weighted K-medoids algorithm, the model instances can be solved optimally or near-optimally. Compared with local search-based algorithms, the center-based approach outperforms metaheuristics such as simulated annealing, variable neighborhood descent, iterative local search and old bachelor acceptance search in terms of solution quality.