世界能源贸易网络的演化特征与能源竞合关系

详尽地探讨全球能源贸易网络的演化特征及国际贸易的竞合关系,可为中国能源贸易政策的制定提供科学支撑。论文运用复杂网络方法,从整体格局出发研究了世界能源贸易网络的演化特征,并重点从供给与需求两方面分析了贸易集团演化与供需大国的能源竞合关系。研究结果表明：20世纪90年代以来,世界能源贸易关系不断趋于复杂化。近年来,能源贸易主体数量基本保持稳定,当前占世界总数近80%的国家/地区均参与能源贸易;世界能源贸易网络同时具有小世界特性与无标度特性;世界能源的进出口格局已发生重塑,能源的出口重心逐渐由东亚、中东、澳洲和欧洲转向了东欧、中东、北美、澳洲和西非等地区,进口重心由东亚、西欧和澳洲向北美、东亚和西欧转移;世界能源贸易网络存在四大集团,分别是以美国为首的贸易集团、欧洲-俄罗斯等国家贸易集团、东亚-东南亚贸易集团和澳大利亚-印度-非洲贸易集团等。地理距离、制度差异、历史文化及政治关系等是贸易集团演化的重要原因;贸易集团内,核心国家间的贸易依赖存在着非对称性,能源需求国进口来源的多元化现象更为突出,东亚、东南亚市场是供给国共同争夺的对象。     

Large wood retention in river channels: the case of the Fiume Tagliamento,Italy

After more than 300 years of widespread and intensive river management, few examples of complex, unmanaged river systems remain within Europe. An exception is the Fiume Tagliamento, Italy, which retains a riparian woodland margin and unconfined river channel system throughout almost the entire 170 km length of its river corridor. A research programme is underway focusing on a range of related aspects of the hydrology, fluvial geomorphology and ecology of the Tagliamento. This paper contributes to that programme by focusing on large wood retention. The paper adopts a simple force:resistance approach at the scale of the entire river corridor in order to identify reaches of the river with a high wood retention potential. Information on the character of the river corridor is derived from 1:10 000 scale topographic maps. A range of indices measured at 330 transects across the river corridor supports a classification of the geomorphological style of the river which reflects the presence and abundance of properties previously identified in the literature as large wood retention sites. This classification provides a qualitative representation of the ‘resistance’ of the corridor to wood movement and thus its overall wood‐retention potential. The map‐derived indices are also used to extrapolate estimates of the ten year return period flood to each of the 330 transects so that the downstream pattern of unit stream power can be quantified as an index representing ‘force’ in the analysis. Although input of wood is an important factor in many river systems, it is assumed not to be a limiting factor along the Tagliamento, where riparian woodland is abundant. Field observations of large wood storage illustrate that wood retention at eight sites along the river reflects the presence and abundance of the features incorporated in the classification of geomorphological style, including the complexity of the channel network, the availability of exposed gravel areas, and the presence of islands. In general at the time of survey in August 1998, open gravel areas were estimated to store approximately 1 t ha⁻¹ of wood in single‐thread reaches and 6 t ha⁻¹ in multiple‐thread reaches. Established islands were estimated to store an average of 80 t ha⁻¹ of wood. Nevertheless, there was considerable variability between sites, and pioneer islands, which are not represented on maps or readily identified from air photographs because of their small size, were estimated to store an order of magnitude more wood than established islands. Furthermore, the wood storage from this sample of eight sites did not reflect variability in estimated unit stream power. A series of areas for further research are identified, which can be explored using field data, and which will throw more light on the processes of wood retention in this extremely dynamic fluvial environment. Copyright © 2000 John Wiley & Sons, Ltd.     

Power law or power flaw?

Since its introduction by Svensson in 1959, the power law curve y = ax^b (where x and y are horizontal and vertical direction, respectively) has been widely used in morphological analysis of glacial trough cross-profiles. The numerical constants a and b are obtained by a linear regression analysis of the logarithmic form of the power law curve (ln y = ln a + b ln x). The value b then gives a measure for the form of the cross-section. However, over the years this form of the power law has endured a lot of criticism. This criticism is well founded, since this particular form of the power law is not suitable for curve fitting in morphological analyses. In this paper a general power law is proposed, of the form y − y₀ = a|x − x₀|^b (where x₀, y₀ are the coordinates of the origin of the cross-profile). A unique and unbiased solution for this equation is obtained with a general least-squares method, thereby minimizing the error between the cross-profile data and the curve, and not between the logarithmic transform of the data and its regression line. This provides a robust way to characterize trough cross-section forms. © 1998 John Wiley & Sons, Ltd.     

大功率激电在铅锌矿勘查中的应用--以辽宁省岫岩县王家堡子铅锌多金属矿为例

辽宁省岫岩县王家堡子铅锌多金属矿位于青城子-许屯铅锌矿带上,通过大功率激电测量查明工作区激电异常特征,综合地质、化探信息,笔者认为矿区侵入岩区带状极化率异常是铅锌矿的找矿标志,沉积岩中石墨矿化引起区域性高极化,根据激电剖面异常特征有利于区分矿与非矿。     

新疆哈尔里克地区主要地层单元含矿性分析

哈尔里克成矿带属铜、金、钨、锡、钼、铁、锰、镍、钴多金属成矿有利地段。为进一步研究成矿带内各地层的含矿性,以天山哈密地区1:5万水系沉积物测量为基础,分析了17种元素及氧化物的特征参数、分布规律及演化特征,对7个地层单元的含矿性进行了分析。结果显示: 哈尔里克地区Au、Sb、Bi呈极不均匀分布(变异系数C_v≥1.5),As、Hg、W为不均匀分布(1.0≤C_v<1.5); 区内元素有对称、正偏、负偏和双峰4种分布类型。各地层单元元素及氧化物浓集系数均表现为波浪形曲折变化。铁族元素主要富集于大柳沟组和头苏泉组; 钨、钼族元素主要富集于头苏泉组; Au主要富集在大柳沟组、大南湖组; 综合分析认为Au、Cu、W、Bi、Fe、Mn、Zn为研究区优势矿种,主成矿元素为Au、Cu、Fe,最佳富集地质时代为奥陶纪,泥盆纪次之,奥陶系大柳沟组为主要含矿地层。     

吉林省浑江市幅1∶50 000水系沉积物测量原始数据集

吉林省浑江市幅1∶50 000水系沉积物测量共采集1961件水系沉积物样品, 采样粒级为-10目~+80目, 平均采样密度为5.1个/km²。采用发射光谱法(AES)、泡沫塑料吸附石墨炉原子吸收分光光谱法(GFAAS)、原子荧光法(AFS)及等离子体质谱法(ICP-MS)分析了Au、Ag、Cu、Pb、Zn、As、Sb、Bi、Hg、W、Sn、Mo、Cd、Co、Cr、Ni 等16种元素, 形成吉林省1∶50 000浑江市幅水系沉积物测量原始数据集。数据集包含有1961件样品以及其16元素的原始数据表1个(Excel), MapGIS格式图集1套(含有1张矿产地质图、1张采样点位图、16张单元素地球化学图、16张单元素异常图)。通过本数据集新发现单元素地球化学异常403处, 综合异常24处, 结合地质、物探、化探、遥感及已有成矿线索圈定金矿找矿靶区3处、铜及多金属找矿靶区2处。本文数据集为该区域提供了一套基础性的数据资源, 为基础地质及其他领域应用提供基础地球化学依据。     

海岛核电厂址的设计基准洪水位研究

随着滨海核电厂址的开发利用日趋饱和,选取海岛作为核电厂址成为一种新思路。针对海岛厂址易受台风灾害影响的问题,本文通过对天文高潮位、海平面上升、可能最大风暴潮增水和最大台风浪四个增水因子的研究来确定厂址的设计基准洪水位。结果表明:该区域10%超越概率的天文高潮位为3.14 m,未来80 a海平面上升幅度为0.31 m。基于MIKE21数值模型,以可能最大热带气旋参数为基础构建了多种假想台风路径,发现:当台风移动方向为NW向,距离厂址中心左侧0.5R(R为台风最大风速半径)时,风暴潮增水达到最大,增水最大值为2.99 m;当台风移动方向为W向,且距离厂址左侧R处时,台风浪波高达到最大,厂址前沿H_1/100波高最大值达到了8.02 m;岛屿东侧遭受的风暴潮和波浪威胁较其他方向更为严重。各水位影响因子组合叠加后海岛核电厂址设计基准洪水位可达11.25 m。相对于其他滨海厂址,海岛厂址的风暴潮增水相对偏小,但受波浪的影响更为显著。     

一种基于滨海核电站海上γ辐射剂量率的智能化自动监测系统研究与设计

基于滨海核电站海上γ辐射剂量率的智能化自动监测系统是一种无人值守的辐射监测装备,可全天候、长时间、在线组网、连续自动测量水面和空气中的γ剂量率、获取水中γ能谱数据并进行核素识别和计算活度浓度,并实时地将监测数据通过无线通信链路和北斗短报文两种形式上传至地面数据服务中心。在非事故情况下,该系统是对核电厂监督性监测系统的重要补充和完善;在发生重大核安全事故或放射性物质泄漏的情况下,能够有效解决传统的派船巡测时方法不标准、数据不及时不连续、人员受照风险大、船只易受污染和行动代价高等问题;在恶劣的极端气象条件下,无人值守的自动监测系统能够为核电站提供实时有效的水体和空气中的γ剂量率、气象、海水温度等监测数据,有效地提升了核电站在极端气象条件下的监测能力,对滨海核电站整体的安全性和可靠性具有一定积极意义。     

Evolutionary investment network and the emerging energy power in Central Asia: From the perspective of cross-border mergers and acquisitions

Journal of Geographical Sciences - Central Asia is emerging as an important pole of global economic and political power, thanks to its unique location at the heart of Eurasia and its abundance in...