钢弹簧浮置板道床在西安地铁中减振效果分析

西安地铁二号线绕行通过西安钟楼,为降低地铁长期运营对钟楼的振动影响,在钟楼段采用钢弹簧浮置板道床进行减振。主要以地铁二号线运行影响下对钟楼的振动监测数据为基础,通过对钢弹簧浮置板道床段和普通道床段的振动实测值比较与分析,得出隧道内减振段和普通段的振动差异,以此评价钢弹簧浮置板道床在地铁应用中的减振效果。     

山西太原盆地全新世地貌演化及其对古人类聚落分布的影响*

人地关系是现代地理学重要的研究课题,其中地貌是影响古人类文化进程的重要因素。基于研究区野外地貌考察和沉积物的光释光年代测定,并利用地理信息系统分析技术,探讨山西省太原盆地全新世地貌演化过程、人类聚落分布变化规律及两者之间的关系。研究结果表明: 从仰韶到夏商时期,太原盆地平原区一直是不适宜人类居住的河流和湖泊环境,而在盆地边缘有一圈环绕盆地的黄土台地,所以人类文化遗址一直呈环状分布于太原盆地边缘。晚更新世,盆地边缘以洪积过程为主,盆地中部以河流过程为主,形成了盆地边缘高、中间低的地势;晚更新世末期到全新世早期,由于盆地中部构造下陷与气候转变为暖湿的共同影响,盆地边缘地带下切形成黄土丘陵或台地。此时,太原盆地的仰韶文化遗址就分布在环盆地边缘的黄土台地和黄土丘陵上。到了龙山早期,盆地东侧中部陷落平原边缘地势稍高的地区,由于河流进一步下切而高出洪水水位,龙山早期先民开始进入这些地势稍高的平原地区活动;盆地西侧清徐—文水一带也转为下切,形成低台地,开始有人类在此台地上活动。到了龙山晚期,盆地平原区及各河流均发生向上加积,导致盆地平原区水位上升,洪水影响扩大到平原边缘地区,太谷—介休一带,龙山晚期先民开始退出平原地区。夏商时期,先民也从清徐—文水一带低台地上退出。约距今3,ka之后,随着灵石隆起段汾河干流的下切,太原盆地边缘地带及中部平原区河流均有不同程度的下切,人类聚落才又开始向平原地区扩展。全新世太原盆地的地貌演化是影响古人类聚落分布的主要因素。     

青海省贵德扎仓寺地热成因机理及开发利用建议

本文通过卫星热遥感影像及航磁、重力异常的宏观性解译热异常空间分布特征,野外实地调查温泉的出露条件和水化学特征,分析研究青海省贵德扎仓寺温泉的热源通道、入渗通道,从而讨论其成因机理和开发利用前景。研究结果表明:扎仓寺温泉泉口温度为93.5℃,与当地气压有关;大气降水和热水沟上游沟谷水为补给源,近东西向张裂为入渗通道,中三叠统砂板岩与印支期花岗闪长岩(γδ₅²)接触变质带为径流通道(热储层),中三叠统砂板岩为盖层,北北西向热光断裂(F₁)为热源通道,属断裂-深循环地热类系统类型;径流通道(热储层)温度可达136.0℃,具备蒸汽发电示范背景条件,而F₁断裂带附近2000 m深度温度可达195.0℃,具备干热岩开发利用前景。     

放牧强度对科尔沁沙地沙质草地植被的影响

为了研究科尔沁沙地沙质草地在不同放牧强度下植被特征的变化规律,比较了围封、中度放牧、重度放牧3种条件下的植被盖度、群落组成、物种多样性、地上/地下生物量和凋落物量等植被特征的变化特征。结果表明:(1)围封、中度放牧和重度放牧沙质草地的优势植物均为一年生植物,但围封和中度放牧中多年生禾本科植物优势度高于重度放牧,重度放牧沙质草地一年生植物所占优势度最大;(2)放牧强度对沙质草地植被盖度、地上生物量及凋落物量有显著影响。随着放牧强度的增加,植被盖度、地上生物量和凋落物量均降低;(3)围封、中度放牧和重度放牧沙质草地物种丰富度及多样性差异均不显著;(4)放牧强度和土壤深度及其交互作用均能影响地下生物量。随着放牧强度的增加,总的地下根系生物量减小。而重度放牧草地中, 3个土壤深度间地下根系生物量差异不显著。放牧改变了沙质草地植物群落的组成、极大降低了植被盖度和生产力;尤其是重度放牧急剧增加了一年生植物的优势、且对浅层根分布的减少影响最大。     

广义S变换地震信号时频分析

广义S变换继承和发展了S变换的优点,其引入了λ、p两个参数,对S变换中固定的基本小波进行了推广和扩展,使得其时窗更灵活多变,在一定程度上提高了非平稳信号分析处理的时频分辨率。通过线性调频信号模拟测试对比,证实了广义S变换的信号聚焦能力明显优于S变换,能够更好地刻画信号的局部特性。最后,以某区二维单炮地震数据为例进行了地震信号的广义S变换时频分析,取得了良好效果。     

Urban expansion in China and its effect on cultivated land before and after initiating “Reform and Open Policy”

Urbanization in China has expanded at an unprecedented speed since the declaration of "Reform and Open Policy"and presented many challenges. Unbalanced regional development, appearance of super megacities and concomitant problems,and conflicts between urbanization and cultivated land protection are three critical problems that Chinese urbanization has to face. To develop new plans for foreseeable future urbanization in China, it is critical to understand the evolving history of cities across China. This study maps urban expansion of 60 typical Chinese cities based on large amount of remote sensing data and the labor-intensive image interpretation method, in order to understand the history of urban expansion from the 1970 s to 2013.Results showed that area of cities expanded 5.23 times compared to their area in the 1970 s. Urban expansion in China accelerated three times(1988–1996, 1999–2006, and 2009–2011) and decelerated three times(1997–1998, 2007–2008, and 2012–2013) over the 40 years. The urban area of South China expanded most significantly 9.42 times, while the urban area in Northeast China expanded only 2.37 times. The disparity among different administrative ranks of cities was even greater than(3.81 times) the differences among different regions. Super megacities have been continuously expanding at a fast rate(8.60-fold), and have not shown obvious signs of slowing down. The proportion of cultivated land among the land sources for urban expansion decreased to a small extent in the 1990 s, but cultivated land continues to be the major land source for urban expansion. Effective future urbanization needs controlling the expansion scale of large cities and reasonably developing medium and small cities, as well as balancing regional development.     

A comparative study of fuzzy weights of evidence and random forests for mapping mineral prospectivity for skarn-type Fe deposits in the southwestern Fujian metallogenic belt,China

Recent studies have pointed out that the widespread iron deposits in southwestern Fujian metallogenic belt (SFMB) (China) are skarn-type deposits associated with the Yanshanian granites. There is still excellent potential for mineral exploration because large areas in this belt are covered by forest. A new predictive model for mapping skarn-type Fe deposit prospectivity in this belt was developed and focused on in this study, using five criteria as evidence: (1) the contact zones of Yanshanian granites (GRANITE); (2) the contact zones within the late Paleozoic marine sedimentary rocks and the carbonate formations (FORMATION); (3) the NE-NNE-trending faults (FAULT); (4) the zones of skarn alterations (SKARN); and (5) the aeromagnetic anomaly (AEROMAGNETIC). The fuzzy weights of evidence (FWofE) method, developed from the classical weights of evidence (WofE) and based on fuzzy sets and fuzzy probabilities, could provide smaller variances and more accurate posterior probabilities and could effectively minimize the uncertainty caused by omitted or wrongly assigned data and be more flexible than the WofE. It is an efficient and widely used method for mineral potential mapping. Random forests (RF) is a new and useful method for data-driven predictive mapping of mineral prospectivity method, and needs further scrutiny. Both prospectivity results respectively using the FWofE and RF methods reveal that the prediction model for the skarn-type Fe deposits in the SFMB is successful and efficient. Both methods suggested that the GRANITE and FORMATION are the most valuable evidence maps, followed by SKARN, AEROMAGNETIC, and FAULT. This is coincident with the skarn-type Fe deposit mineral model in the SFMB. The unstable performance experienced when FORMATION was omitted might indicate that the highest uncertainty and risk in follow-up exploration is related to the sequences. In addition, the performance of the RF method for the skarn-type Fe deposits prospectivity in the SFMB is better than the FWofE; therefore, it could be used to guide further exploration of skarn-type Fe prospects in the SFMB.     

中国古代风景名胜地图艺术性探讨

中国古代风景名胜地图脱胎于中国山水画,因此与中国山水画有着千丝万缕的关系。同时,由于受时代条件的限制,古人更多将关注点放在地图的艺术特征层面上。古代风景名胜地图是中国特有艺术与文化的产物,集中国传统思想、文化、书法、绘画等多种艺术于一身,具有重要的文化与艺术价值,值得探寻与传承。本文从地图学的符号设计、制图综合、比例尺、方位与色彩、注记与文字、传统思想等多种角度对中国古代风景名胜地图的艺术特征进行了探讨,并以图的形式对相应特征作了阐述。这些艺术特征是中国传统文化的代表与结晶,有博大精深的思想内涵,尤其是儒家、道家、佛家的思想从根源上无形有形地影响古代风景名胜地图的艺术性的发展。古代风景名胜地图的艺术性能为当代以二维居多、艺术性严重不足的现代地图发展提供重要的借鉴意义,并且对于弘扬中国传统文化的今天,具有重要的文化战略意义与传承价值。     

科尔沁沙地中南部34种植物叶功能性状及其相互关系

以科尔沁沙地中南部34种主要植物为研究对象,分别测定叶片鲜重(FW)、干重(DW)、干物质含量(LDMC)、面积(LA)和比叶面积(SLA),比较不同生活型(一二年生草本、多年生草本、灌木)和功能型(C₃、C₄植物)的叶片性状的差异性,探讨沙地植物叶片性状相互之间的内在联系及其对环境的适应性。结果表明:一二年生草本的LDMC(0.23 g·g^-1)显著小于多年生草本(0.31 g·g^-1)和灌木(0.32 g·g^-1);而一二年生草本的SLA(22.14 m²·kg^-1)显著大于多年生草本(17.18 m²·kg^-1)和灌木(13.41 m²·kg^-1)。一二年生和多年生C₄植物的LDMC显著大于C₃植物;多年生C₄植物SLA显著大于C₃植物;C₃植物的LDMC表现为一二年生草本<多年生<灌木。沙地植物的叶鲜重、叶干重和叶面积三者间极显著正相关,植物叶干重与SLA显著负相关;C₄植物和多年生植物叶干重与SLA显著负相关。沙地不同生活型、功能型植物叶片的功能性状差异明显,沙地灌木和多年生植物能够较强的适应干旱环境,一二年生草本则具有较强的保持体内营养和获取土壤资源的能力。     

微小位移测量装置设计

微小位移测量装置的设计是以51单片机为控制核心,采用DDS芯片产生稳定的100 kHz的正弦波信号,使用差分输出来驱动差动变压器输入极,通过检测变压器两个次级线圈的电压,并对两电压进行计算处理,从而得出位移量。经过巧妙的选取直流电机和电机驱动电路,很好地完成了磁棒的精确闭环控制,控制精度能够达到0.5 mm。