新疆S214公路台特玛湖干涸湖盆段风沙危害及防治

新疆S214（考干-米兰,考米线）公路位于库鲁克塔格沙漠东南缘,穿越台特玛湖干涸湖盆。由于该区气候干旱,风力强劲,沙源丰富,流动沙丘广布且快速移动,风沙危害对公路运输构成严重威胁。通过对风沙环境和风沙危害定位观测和土壤水盐特征系统调查,确定了风沙危害极为严重的公路区段,提出了合理的风沙防护措施及防沙体系结构。结果表明：该区具有明显的单风向风况,主要盛行ENE和NE风,偶有反向风沙活动,起沙风频率、输沙势、输沙率极高,属于高能-大比率风能环境;受土壤水分、盐分含量影响,地表紧实度差异较大,部分地段为极疏松的沙层,部分地段为紧实的盐壳;S214公路风沙危害防护区段为K4+900~K18+200,设计建造的阻-固-输相结合的机械-植物复合防沙体系,防沙效果明显,保障了道路安全运营。这一强风沙、高盐区公路防沙体系建设模式可为类似环境地区工程防沙提供借鉴。     

Automated threshold selection methods for extreme wave analysis

The study of the extreme values of a variable such as wave height is very important in flood risk assessment and coastal design. Often values above a sufficiently large threshold can be modelled using the Generalized Pareto Distribution, the parameters of which are estimated using maximum likelihood. There are several popular empirical techniques for choosing a suitable threshold, but these require the subjective interpretation of plots by the user.In this paper we present a pragmatic automated, simple and computationally inexpensive threshold selection method based on the distribution of the difference of parameter estimates when the threshold is changed, and apply it to a published rainfall and a new wave height data set. We assess the effect of the uncertainty associated with our threshold selection technique on return level estimation by using the bootstrap procedure. We illustrate the effectiveness of our methodology by a simulation study and compare it with the approach used in the JOINSEA software. In addition, we present an extension that allows the threshold selected to depend on the value of a covariate such as the cosine of wave direction.     

海洋动物体石油烃污染评价标准参考值的探讨

目前,国内外尚无颁布任何海洋生物石油污染评价标准,为了满足海洋生物石油污染评价的需要,本文采用综合分析与毒理学分析相结合的方法,探讨和提出了海洋动物石油污染评价标准参考值,海洋鱼类、贝类和甲壳类的石油污染评价标准参考值（干重）分别为１５、７０ 和２５ ｍ ｇ／ｋｇ。     

中国"互联网+"发展的空间关联网络及其影响因素——基于社会网络分析视角的实证研究

借助社会网络分析方法研究“互联网+”发展的空间关联网络特征,并利用QAP方法探究中国“互联网+”空间关联网络的影响因素。研究发现,“互联网+”发展的空间关联呈现显著网络特征,可划分为“净溢出”“经纪人”“主受益”以及“双向溢出”四大类型板块,并且板块内部具有较明显的“等级”属性。技术创新、基础设施、人力资本、市场发展、对外开放对“互联网+”发展的空间关联网络存在正向影响。地理距离对“互联网+”空间关联网络存在抑制作用,随着地理距离的不断增大,“互联网+”的知识溢出和流动效应逐步衰减。     

乌兰布和沙漠东南缘湖泊群消涨与驱动因素

湖泊是对环境变化响应敏感的地理单元,湖泊消长与响应机制研究对维持区域生态系统稳定具有重要意义。基于1999—2018年Landsat、气象、水文和农业种植面积等多种数据,在ArcGIS平台中利用改进归一化差异水体指数(MNDWI)及目视修正方法提取了乌兰布和沙漠东南缘湖泊群空间信息,运用统计学方法对主要驱动因子与湖泊消涨的关系进行了分析。结果表明:1999—2018年乌兰布和沙漠东南缘大湖泊(面积大于100 hm²)在面积上占优势,小湖泊(面积小于100 hm²)在数量占优势。趋势分析表明大湖泊面积和数量呈显著性减少趋势(相关系数分别为R=0.624 > R_18,0.01=0.561和R=0.648 > R_18,0.01=0.561);小湖泊减少趋势不显著。在空间分布格局上,研究区中部是大湖泊稳定分布区,大湖泊数量11~23个,面积2 208~4 581 hm²。研究区湖泊消长主要受到年实际引黄水量、农田面积和地下水埋深的影响。其中,实际引黄(河)水量影响所有湖泊(P≤0.01),而农田面积和地下水埋深分别对大湖泊(P≤0.01)和小湖泊(P≤0.05)影响显著。用这3个因子分别构建的多元回归模型显示,在大、小湖泊面积和数量预测方面,精度分别达到75.7%和60.5%以上。     

以流动看世界——基于彼得·阿迪《流动性》的研究述评

“流动”正改变着人们的生存、生活和生产方式。流动性经历了从学科间独立的分散研究,到以地理学和社会学为主导的多学科研究,再转向新流动性范式下的跨学科研究。其中,彼得·阿迪（Peter Adey）的《流动性》（Mobility）（第二版）是一部梳理流动性演变脉络、解读理论并联系案例和方法的力作。因此,文章从流动性研究产生的背景、主要内容、研究方法与运用3个方面凝练该书观点,指出未来研究要跳出以二元对立看问题的思维方式,用一种网络化、关系式和辩证的思维洞察世界,在深度理解流动的意义、政治、实践和媒介基础上进行流动性研究。最后,文章基于国内研究现状,提出未来可以从流动性政治、流动性时空维度、旅游与流动性、流动主体的多元化、流动性研究方法等几个方面展开深入研究。     

中国经济地理学发展困境与对策刍议

探讨了当前中国经济地理学发展中出现的哲学、分支体系、理论、方法论、研究方向和高等教育等6方面问题,并从中国经济地理学学科建设角度,分别对中国经济地理学的哲学、学科分支、理论体系、方法论和研究领域进行了梳理,对各自发展作了展望。     

“雪龙”号科考船在冰区航行的船体振动测量研究

船舶在冰区航行时,船体会受到多种类型激振力的作用而产生不同程度的结构振动。船体振动会对船体结构安全以及船上人员的正常工作产生不利影响。船体结构振动的现场测量可较为准确地分析船体振动的基本特性,确定船体振动与外界荷载因素的对应关系。在2015—2016年中国第32次南极科学考察过程中,对"雪龙"号极地科学考察船的冰激振动开展了现场测量。本研究对比了船体在无冰区和冰区航行过程中的船体振动变化,分析了船体在不同航速、冰厚以及不同破冰航行方式下的振动规律。测量结果表明:船体冰激振动随着航速和冰厚的增加而显著增大;在船体采用冲撞式破冰时横向振动最为明显,而在连续式破冰时,垂向振动最为明显。以上研究可为冰区航行中船体振动的现场监测技术提供有益参考,并有助于分析海冰对船体振动规律的影响。     

土地利用变化对喀纳斯自然保护区生态系统服务价值的影响

应用喀纳斯自然保护区1980,2005年两个时期的LandsatTM影像解译数据,采用Costanza生态系统服务价值计算公式,参照中国单位面积生态服务价值系统,确定了喀纳斯自然保护区生态系统单位面积生态服务价值系数,分析了保护区土地利用变化对其生态系统服务价值的影响.结果表明,保护区林地面积在减少,草地,水域、建设用地面积有所增加;研究期内生态系统服务价值从26.79亿元减少到26.02亿元,天然有林地和高覆盖度草地的减少是生态服务价值降低的主要原因;保持土壤、维持生物多样性、气候调节等各单项功能服务价值均呈现不同程度的减少,说明保护区生态环境不断趋向恶化.     

Sequence architecture and depositional evolution of the Ordovician carbonate platform margins in the Tarim Basin and its response to tectonism and sea‐level change

The sequence architecture and depositional evolution of the Ordovician carbonate platform margins in the Tarim Basin, China, were formed in response to the interplay of tectonism and sea‐level change, their history being documented by the integrated analysis of many seismic lines, drilling and outcrop data. The Ordovician carbonate system in the basin is divided into four composite sequences defined by major unconformities. Each sequence consists of a regional depositional cycle from transgression with an onlapping transgressive systems tract (TST) to regression with a prograding highstand systems tract (HST), and can be further subdivided into 10 third‐order sequences based on subordinate discontinuous boundaries at the carbonate platform marginal zones. Constrained by the marginal slope of the early‐rifted Manjiaer aulacogen, the carbonate platform margins of the Lower and Middle Ordovician that prograded eastward in an arcuate belt extending generally north‐south across the northern part of the basin. The development of the Tazhong uplift due to compression resulted in an extensive paleokarst hiatus between the Middle and the Upper Ordovician in the south‐central basin, and subsequently constrained the formation of a peninsula‐shaped carbonate platform whose margins were controlled by marginal thrust‐fault belts of the paleo‐uplift during the Late Ordovician. In the northern basin, the Late Ordovician carbonate platform margin developed around the marginal slope of the Tabei paleouplift. The transgressive–regressive cycles of the carbonate system are comparable and seem to have occurred simultaneously across the entire basin, suggesting that the cyclic sequence architecture was fundamentally controlled by eustatic fluctuations. Stacking patterns of the composite sequences varied due to the interplay between the accommodation produced by tectonism and sea‐level change, and the carbonate production rate. The reef–shoal facies complexes that developed along the platform margins, with paleokarst development at unconformities, constitute the major reservoir of large petroleum reserves in the basin.