小比例尺地图投影设计方法研究

针对地图投影的设计通常只能由具有数学与制图专业知识的专家完成的不足,该文对Robinson完全视觉化的地图投影方法进行扩展,提出一种基于软件方法的小比例尺世界地图投影设计方法,使普通用户能够快速创建新的地图投影或是修改一个已存在的投影:利用纬线长、纬线与赤道的距离、纬线弯曲度、经线弯曲度四个参数描述一种投影,并通过对比例变形、面积变形、角度变形、可接受的变形度等变形指标的视觉化展示向用户直观反映新投影的变形程度;同时通过可结构化的指数从整体上评估区域和角度变形。最后以Aitoff投影为例验证了方法的正确性。     

基于风廓线雷达的湖北梅雨期暴雨中小尺度特征

针对2016年湖北梅雨期3次(“6·19”、“7·5”和“7·19”)暴雨过程,首先对比了汉口站探空数据与汉口、咸宁两个风廓线雷达站水平风速、风向,发现“6·19”和“7·5”过程汉口风廓线雷达站3 km以下水平风速和探空数据较为接近,而3次过程中咸宁风廓线雷达站8 km以下水平风向、风速和汉口站探空数据基本吻合。在此基础上利用风廓线雷达资料并结合常规、加密自动气象站资料,对3次过程中水平风场、平均垂直速度及其变率、水平风速垂直切变、大气折射率结构常数(C■)等进行分析。结果表明：(1)降水开始前西南风速明显增大,中层干冷空气入侵和地面冷池形成的中尺度偏东气流是“6·19”过程50站出现大于等于17.2 m·s^-1大风的主要原因,“7·5”和“7·19”过程西南急流长时间维持及1 km以下的偏东气流则是短时强降水持续时间较长的诱因;(2)梅雨期暴雨期间风廓线雷达观测的水平风速垂直切变、平均垂直速度及其变率随高度变化较小,较强上升运动区域主要集中在4 km高度以下;(3)C■显示强降水发生前大气水汽含量有一增加过程,且整层水汽含量深厚,C■大值区的消失对应降水结束。     

太阳大气中的光球亮点

首先是对太阳光球亮点近年来研究工作的总结。光球亮点是一种发生在太阳光球上宁静区域的的小尺度和短寿命增亮现象,平均直径在100～300knm之间,平均寿命约为几分钟。光球亮点的研究对于光球辐射和磁场性质的认识具有重要意义。过去的观测显示,绝大多数光球亮点的产生和演化与磁场,特别是光球上的小尺度磁场的演化密切相关,比如,两个同极性磁场的合并,或者反极性磁场的对消,或者一个同极性磁场的分裂,均可以促使光球亮点产生或消失。基于这样的观测结果,统计研究了2722个光球亮点(1600A)与光球上偶极磁元的关系,发现大约有1/3的光球亮点出现在偶极磁元中心附近。     

智利小规模金属采矿（SSM）业对环境影响与运营方式

智利小规模采选业因分布分散且缺乏相应的环保技术与资金投入,其对环境造成了一定的影响。在智利法律系统监管和支持下,该小规模采选业得到有序发展。同时,小规模金属采选业与智利法律规定的大中型矿产开发项目须完成试验性工业开采(即小规模开发实验)存在一定联系。本文通过调查智利中北部第三、第四和第六区小型开采规模的铜、金和银矿山,分析其生产经营过程中对环境的潜在影响因素,剖析小规模金属选场对智利环境带来的影响,总结金属矿小规模采选业的规范性运营方式,找出法律规定与产业运营的内在联系。建议我国企业在智利进行矿产勘探和可行性研究中重视小规模采选试验与规模性勘查工作的合理有序结合。     

Generation of resonance transition emissions in the solar atmosphere

We derive formulas for the radio flux generated in solar flares by the resonance transition mechanism. This mechanism is shown to produce the observed decimeter-wave emission in continuum radio bursts at a level of small-scale irregularities of ～10^?6–10^?7. Thus, an analysis of continuum decimeter emission offers a unique opportunity to study small-scale turbulence in solar flares.     

钢悬链线立管与海床相互作用小尺寸三维试验研究

围绕钢悬链线立管(SCR)与海床的相互作用,在水箱内开展三维试验研究,研究在不同模拟运动激励下SCR触地点的应力状态。针对当前模拟试验中,全尺寸试验耗资巨大,且试验环境难以控制,缩尺试验大多模拟立管二维运动等现状,提出一套简单易行的三维管土作用试验装置,通过横向、纵向、垂向三个方向轨道位置的合理布置,使得立管可在单向、二维耦合和三个方向同时运动,对模型立管的顶端、底端的边界条件进行处理,通过驱动器在顶端施加位移,模拟在周期运动作用下,立管触地区与土的相互作用,在三维空间内研究立管的力学特性。由此指导立管的整体设计与分析,对保证SCR在深水油气开采中的安全可靠性,具有非常重要的意义。     

Artisanal and small-scale mining (ASM) in sub-Saharan Africa: Re-conceptualizing formalization and ‘illegal’ activity

This article contributes to the debate on the formalization of artisanal and small-scale mining (ASM) – low-tech, labour-intensive mineral extraction and processing – in developing countries. A unique sector populated by an eclectic group of individuals, ASM has expanded rapidly in all corners of the world in recent years. Most of its activities, however, are informal, scattered across lands which are not officially titled. But growing recognition of the sector's economic importance, particularly in sub-Saharan Africa, has forced donors, and to some extent, policymakers, to ‘rethink’ development strategies for ASM. As part of broader moves to improve the regulation of, and occasionally intensify the delivery of assistance to, the sector, many are now searching frantically for fresh ideas on how to bring operations into the legal domain, where, it is believed, they can be regulated, monitored and supported more effectively. A challenging exercise, this entails first determining, with some degree of precision, why people choose to operate informally in this sector. Drawing on analysis from the literature and findings from research conducted in Ghana and Niger, it is argued that the legalist school (on informality) in part explains how governments across sub-Saharan Africa are ‘creating’ bureaucracies which are stifling the formalization of ASM activities in the region. A more nuanced development strategy grounded in local realities is needed if formalization is to have a transformative effect on the livelihoods of those engaged in ASM in the region and elsewhere in the developing world.     

SMALL‐SCALE INDUSTRY AS A SPONGE? EMPIRICAL SURVEY IN THE CENTRAL REGION,GHANA

It has been posited that small‐scale industry – businesses with less than 30 workers – provides a large share of employment and income in Ghana. This paper examines the proposition that while such enterprises in the informal sector are said to act as a sponge to soak up surplus labour in marginal activities, they are unprofitable. Using data from a survey in 1998 of 175 micro and small‐scale enterprises in the Central Region of Ghana, the paper also confirms problematic aspects of employment in this sector including the lack of formal contracts, irregular pay, low remuneration, non‐existent social protection and only marginal employment growth. The implication is that the small‐scale industry sector is not economically sustainable in its present form in Ghana.     

In-channel woody vegetation controls on sedimentary processes and the sedimentary record within alluvial environments: a modern example of an anabranch of the River Loire, France

A multidisciplinary approach was used to analyse the role of pioneer trees (Populus nigra) on bar formation in the modern fluvial system of the River Loire (France). Data were collected on seven plots located on a secondary channel, chosen for their vegetation cover and their sedimentary context. Physical features of vegetation, topographical evolution, sediment grain size and flow velocity were investigated during and after floods between 2001 and 2003. Woody vegetation responds morphologically to fast‐flowing waters and sediment deposition. These adaptations influence the role played by trees on local sedimentary processes. Some morphological types of trees exert a strong influence during flood events by deflecting, reducing or increasing the flow energy. As a consequence, the evolution of bedforms, distribution of sediment grain size and slopes are controlled by the flood type, the morphological context (i.e. high‐ or low‐energy zones), the morphology of the vegetated bar and the characteristics of vegetation. Conceptual models are proposed to account for local processes and evolution of tree groves. The first model, which describes the behaviour of groves during a single flood, underlines the sediment deposition downstream of the trees and the trapping of bedload sediments. During the falling stage of the flood, the reorientation of current streams, constrained by both local bed topography and woody vegetation, induces transverse sediment fluxes. For these water levels, the control exerted by trees on small‐scale sedimentary processes becomes significant. The second model shows the evolution of vegetation bands over several flood events. In particular, it describes the influence of vegetation on the fixing and reworking of bedload sediments during the falling limb of the hydrograph. The coalescence of vegetation‐induced bedforms and the resulting morphological changes increase the deflection power of the vegetated bar, inducing the deposition of finer sediments.