敦煌莫高窟风沙危害综合防护体系探讨

通过对敦煌莫高窟防沙历史的综合总结和分析,认为莫高窟作为我国乃至世界古代灿烂文化艺术的瑰宝,是甘肃对外交流的主要窗口之一,也是我国重要的旅游地之一。单纯的消极人工清沙已远远不能适应现代社会对生态环境质量的需要和旅游业作为该地区经济发展基本点的要求。那么,创造一个良好的旅游生态环境及文物保护工作环境,不仅有利于整个窟区生态环境的改善,且其示范效应将带动本地区乃至整个河西地区的荒漠化治理。根据风沙环境特征,提出了莫高窟防护体系建立的主导思想是:以防治西北、西南主害风为主,根据鸣沙山、砂(砾)质戈壁、窟顶崖面等不同地带的具体风沙运动规律,采取以固为主,固、阻、输、导相结合的防护原则,以切断或削弱鸣沙山沙源和固定流沙,并消除沙砾质戈壁面的就地起沙为目的,建立一个由工程、生物、化学措施组成的多层次、多功能的综合防护体系,从根本上消除风沙活动对莫高窟的危害。同时对莫高窟综合防护体系建设的总体布局及防护宽度、砾石铺压的基本原理作了一个初步的探讨。     

基于重力模型的中国城市体系空间联系与层域划分

新中国成立以来,中国大陆城市体系空间格局发生了深刻的变化。传统的城市体系空间联系主要从人流、物流、技术流、信息流、金融流进行数据的收集和分析,也有运用图论原理进行Rd链分析。近来,随着社会主义市场经济的迅速发展,城市之间的联系变得异常复杂、数据不易得到。本文试图运用重力模型方法对中国城市间的空间联系强度进行定量计算,据此刻画中国城市体系的空间联系状态和结节区结构。从研究结果看,所得结论与实际情况基本吻合。     

Assistance networks in seafood trade – A means to assess benefit distribution in small-scale fisheries

This article addresses the connections between value chain actors in the tropical-marine small-scale fisheries of Zanzibar, Tanzania, to contribute to a better understanding of the fisher-trader link and how connections in general might feed into livelihood security. A sample of 168 fishers and 130 traders was taken across 8 sites through questionnaires and observations. The small-scale fishery system is mapped using a value chain framework both traditionally and from a less economic point of view where the assistance-exchange networks between fishery actors add another layer of complexity. Auxiliary actors previously disregarded emerge from the latter method thus shedding light on the poorly understood distribution of benefits from seafood trade. Female actors participate quite differently, relative to males in the market system, detached from high-value links such as the tourist industry, and access to predetermined or secured sales deals. Data shows that the fisher-trader link is not as one-sided as previously presented. In fact it has a more symbiotic exchange deeply nested in a broader trading and social system. Expanding the analysis from this link by taking a further step downstream highlights traders’ own sales arrangements and the social pressures they are under in realizing them. A complex picture, inclusive of diversified perspectives, on interactions in the market place is presented, as well as a reflection on the remaining critical question: how to integrate this type of data into decisions about future fisheries governance.     

基于LMS滤波的地基增强系统电离层异常检测

针对地基增强系统(GBAS)中传统电离层异常检测方法无法同时兼顾检测精度与灵敏度的问题,通过构造单通道变步长最小均方(LMS)自适应滤波器以抑制伪码-载波偏离度高频噪声。单通道LMS自适应滤波器是在标准双通道LMS自适应滤波器的基础上,利用被检测信号短时相关性及其量化噪声的非相关性,构造一个采用被检测信号延时量作为参考输入的自适应滤波器,同时对Sigmoid函数进行改进,使得自适应滤波器在前期收敛速度快,且待滤波器收敛后保持较高稳定性。实验结果表明,在相同卫星仰角与电离层时间梯度值下,采用LMS自适应滤波器后电离层异常检测时间缩短,且当电离层时间梯度较小时,该方法也能够实现异常检测,验证了其有效性。     

TMI、AMSR-E全球海表温度与Argo近海表温度的比较

本文将TMI（Tropical Rainfall Measuring Mission （TRMM）Microwave Imager）和AMSR-E（Advanced Microwave Scanning Radiometer for the Earth Observing System）卫星观测的全球海表温度与Argo浮标观测的近海表温度进行了比较。并检验了影响海温变化的因素,包括风速、水汽含量、液态云和地理位置。结果显示,TMI、AMSR-E海表温度与Argo近海表温度均明显相关。在低风速时,TMI、AMSR-E海表温度整体比Argo近海表温度高。在低风速时,TMI比AMSR-E海表温度更接近Argo近海表温度,但TMI海表温度在高纬可能没有经过良好校正。温度差异显示,在低水汽含量时,TMI和AMSR-E海表温度显示出暖的差异,代表TMI和AMSR-E海表温度在高纬均没有经过良好校正。黑潮延伸区的海表温度变化要比海潮区明显。春季在黑潮延伸区,卫星观测的海表温度与Argo近海表温度差异较小。在低风速时,TMI和AMSR-E海表温度均经过了良好校正,而TMI比AMSR-E效果更好。     

A study on one-dimensional consolidation of layered structured aquitard soils in a leakage system

Analytical solutions expressed using the hydraulic head for the one-dimensional consolidation of layered structured aquitard soils in a leakage system are deduced by transforming the n-layered structured soils into n + i (i = 1,2,…, n)-layered soils with gradually changing thicknesses, therein considering the behaviors of structured aquitard soils. The solutions are given in the case of instantaneous and linear decreasing confined aquifer water levels. By comparing three different examples, the effects of the structured behaviors on the consolidation characteristics are analyzed for the instantaneous decline of the confined aquifer water level.     

面向“未来地球”计划的区域可持续发展系统解决方案研究——对人文—经济地理学发展导向的讨论

“未来地球”计划旨在提出系统解决可持续发展问题方案的学术思想、顶层设计、核心内容、研究方法等,为人文—经济地理学研究区域可持续发展的未来走向提供了较好的借鉴意义。在分析“未来地球”核心理念的基础上,阐述了人文—经济地理学面临的发展机遇和发展定位,并探索“未来地球”计划的5 个优先事项对面向全球可持续发展问题的系统解决方案。并对区域可持续发展系统研究的目标、视角和路径进行了讨论,在此基础上,从应用基础研究和应用实践两个层次探讨了针对区域可持续发展问题的系统解决方案的学术思路。以“未来地球”研究计划为参照标尺,按照区域可持续发展系统解决方案研究的逻辑架构,从提高预测能力和评估水平、调控过程和管制模式的应用研究以及体制机制设计等3个方面,讨论了面向“未来地球”的中国人文—经济地理学发展导向。     

交通网络内生产要素集散机理及模式研究--以沈大高速公路为例

文章以交通网络环境下生产要素的集聚与扩散作为研究对象,以"点-轴系统"理论作为生产要素集聚与扩散的理论基础,分析了高速公路占据突出重要地位的交通网络的生产要素集聚与扩散的模式,并以沈大高速公路为例进行实地论证。     

近年来强沙尘暴天气气候特征的分析研究

2000～2002年春季(3～5月)中国北方有12次强沙尘暴天气过程发生,其中11次与蒙古气旋有关.作者从干旱气候背景、环流状况、沙尘源、沙尘路径及天气系统等方面进行了分析,并集中对引发强沙尘暴的蒙古气旋进行了诊断分析.结果表明:在这3年中,春季我国北方强沙尘暴天气主要与蒙古气旋的发展移动有关,气旋冷锋后的大风是强沙尘暴天气发生的主要动力因子;蒙古国南部、巴丹吉林沙漠、腾格里沙漠、乌兰布和沙漠和毛乌素沙地是强沙尘暴过程的主要沙尘源地;影响我国的强沙尘暴的沙尘路径至少可分为3种类型,即偏西路径、西北路径和南疆盆地型,以西北路径居多;我国北方春季的连续干旱、气温偏高及冷空气活跃是强沙尘暴天气形成的重要气候背景.     

Global distributions of storm-time ionospheric currents as seen in geomagnetic field variations

To investigate temporal and spatial evolution of global geomagnetic field variations from high-latitude to the equator during geomagnetic storms, we analyzed ground geomagnetic field disturbances from high latitudes to the magnetic equator. The daytime ionospheric equivalent current during the storm main phase showed that twin-vortex ionospheric currents driven by the Region 1 field-aligned currents （R1 FACs） are intensified significantly and expand to the low-latitude region of-30~ magnetic latitude. Centers of the currents were located around 70~ and 65~ in the morning and afternoon, respectively. Corresponding to intensification of the R1 FACs, an enhancement of the eastward/westward equatorial electrojet occurred at the daytime/nighttime dip equator. This signature suggests that the enhanced convection electric field penetrates to both the daytime and nighttime equa- tor. During the recovery phase, the daytime equivalent current showed that two new pairs of twin vortices, which are different from two-cell ionospheric currents driven by the R1 FACs, appear in the polar cap and mid latitude. The former led to enhanced north- ward Bz （NBZ） FACs driven by lobe reconnection tailward of the cusps, owing to the northward interplanetary magnetic field （IMF）. The latter was generated by enhanced Region 2 field-aligned currents （R2 FACs）. Associated with these magnetic field variations in the mid-latitudes and polar cap, the equatorial magnetic field variation showed a strongly negative signature, produced by the westward equatorial electrojet current caused by the dusk-to-dawn electric field.