基于Matcom 平台的VC + + 与Matlab 混合编程地震正演模拟

正演模拟是地震勘探的重要方法之一。为解决基于Matcom 4. 5 的VC + + 与Matlab 接口程序的地震正演模拟问题,通过用Matcom 4. 5 与VC + + 结合编程的新方法实现EDA 介质中的地震波正演模拟的实例,结果显示Matcom 实现VC + + 与Matlab 混合编程并提高了编程效率。     

深层搅拌桩桩体强度和单桩承载力的影响因素及分析

深层搅拌法作为软土地基处理的一种方法在我国已经得到广泛应用。但在其施工过程中，常会由于冒浆、复搅深度、土体搅拌不均和外加剂选择不当等问题影响桩体强度和单桩承载力。在深层搅拌法施工过程中可以采用复搅法、喷搅法或合理选择外加剂来避免上述情况的发生，以提高桩体强度和单桩承载力。     

时间异质性视角下对中国城市形态多中心性演化的探究

针对现有文献对于城市内部多中心空间结构演化过程中的时间异质性探讨不足的问题,本研究基于1 km格网人口数据,采用相对最小阈值法测度2005—2015年全国地级市城市内部形态多中心性,使用系统聚类算法对其时序演化模式进行归纳,并通过混合效应模型将时间异质性纳入到城市多中心性演化相关因素的探索中。研究发现：① 中国城市多中心结构在2010年前后基本形成;② 共识别了五种多中心的演化模式;③ 多中心性与区位特征、人口特征、经济水平、基础设施和城市规模显著相关;④ 中国城市多中心性演化在时间序列上呈现出差异性,符合扩散-聚合的规律,与经典城市结构理论相契合。研究发现及使用的相应方法有助于推进对于城市多中心性发展规律的进一步理解。     

Evolution of a mixed siliciclastic‐carbonate deep‐marine system on an unstable margin: The Cretaceous of the Eastern Greater Caucasus,Azerbaijan

Mixed siliciclastic‐carbonate deep‐marine systems (mixed systems) are less documented in the geological record than pure siliciclastic systems. The similarities and differences between these systems are, therefore, poorly understood. A well‐exposed Late Cretaceous mixed system on the northern side of the Eastern Greater Caucasus, Azerbaijan, provides an opportunity to study the interaction between contemporaneous siliciclastic and carbonate deep‐marine deposition. Facies analysis reveals a Cenomanian–early Turonian siliciclastic submarine channel complex that abruptly transitions into a Mid Turonian–Maastrichtian mixed lobe‐dominated succession. The channels are entrenched in lows on the palaeo‐seafloor but are absent 10 km towards the west where an Early Cretaceous submarine landslide complex acted as a topographic barrier to deposition. By the Campanian, this topography was largely healed allowing extensive deposition of the mixed lobe‐dominated succession. Evidence for irregular bathymetry is recorded by opposing palaeoflow indicators and frequent submarine landslides. The overall sequence is interpreted to represent the abrupt transition from Cenomanian–early Turonian siliciclastic progradation to c. Mid Turonian retrogradation, followed by a gradual return to progradation in the Santonian–Maastrichtian. The siliciclastic systems periodically punctuate a more widely extensive calcareous system from the Mid Turonian onwards, resulting in a mixed deep‐marine system. Mixed lobes differ from their siliciclastic counterparts in that they contain both siliciclastic and calcareous depositional elements making determining distal and proximal environments challenging using conventional terminology and complicate palaeogeographic interpretations. Modulation and remobilisation also occur between the two contemporaneous systems making stacking patterns difficult to decipher. The results provide insight into the behaviour of multiple contemporaneous deep‐marine fans, an aspect that is challenging to decipher in non‐mixed systems. The study area is comparable in terms of facies, architectures and the presence of widespread instability to offshore The Gambia, NW Africa, and could form a suitable analogue for mixed deep‐marine systems observed elsewhere.     

基于谐波分析和线性混合模型的河北平原区土地覆被分类研究

土地覆被分类是研究土地利用/覆被变化的基础数据和关键环节。以16d合成MODIS-EVI时间序列数据为主要数据源,采用谐波分析方法分析不同土地覆被类型的季节性变化规律和物候特征差异,引入谐波特征值构建线性混合模型,提取不同端元的丰度值。从土地覆被类型较齐全、谐波特征具有代表性的石家庄地区高空间分辨率影像上选择训练样本,确定MODIS纯净像元和混合像元的划分阈值,对河北平原区进行土地覆被分类制图。结果表明,与河北省县级土地调查统计数据对比,一年两熟耕地、一年一熟耕地、园地及有林地、自然陆地表面的总量精度分别为90.19%、86.17%、85.96%和77.82%,平均总量精度为85.03%;与石家庄地区9个县(市)一年两熟耕地和一年一熟耕地基于TM的分类结果对比,平均面积相对误差分别为10.25%、13.98%。受粗空间分辨率和合成周期、水热条件以及种植模式破碎化限制,混合像元主要集中在河北平原中东部地区,一年两熟耕地、一年一熟耕地、园地及有林地混合面积比重较大。     

基于小波变换和混合熵编码的山区格网DEM数据压缩

用信息论的观点对山区格网DEM数据进行了分析,发现山区DEM数据具有信息熵高、冗余度低的特点,从而导致了无损压缩方法——熵编码对其进行压缩的压缩比低。为了实现对DEM数据高效、高精度的压缩,笔者提出利用具有线性相位的双正交小波变换以及混合熵编码方法(Huffman编码加游程编码)对山区格网DEM数据进行压缩。实验结果表明,该方法在基本不损失DEM数据精度的情况下,可获得比无损压缩方法高得多的压缩比。     

Soil degradation assessment in mixed farming systems of southern Africa: use of nutrient balance studies for participatory degradation monitoring

Soil degradation assessments for mixed farming systems of the Molopo Basin (North West Province, South Africa and Southern District, Botswana) are provided from farmer–based research, designed to quantify nutrient fluxes across the farming system and to analyze the social, economic, political and environmental factors affecting nutrient management practices. This paper discusses the practical difficulties of how to use participatory farmer–led studies to assess soil degradation extent and its causes, and of then disseminating this information to farming communities and policymakers. Nutrient balance studies show that land degradation is evident on arable fields as soil nutrient depletion (the main threat to poorer manure–reliant farmers) and soil acidification (the main threat to wealthier farmers who have become dependent on inorganic fertilizer additions). Integrated nutrient management strategies involving both compound fertilizer additions and regular manure inputs can mitigate most soil degradation even on the sandy infertile Kalahari soils, but remain infrequently practised. The need to retain nutrient flows through the livestock sector from rangeland to arable land is thus vital to environmental sustainability and offers an applicable entry point for agricultural development initiatives and support. Factors identified as threatening the flow of nutrients from rangelands to arable lands include policy settings in terms of the different support programmes offered to communal farmers, village–level extension advice, household poverty levels and labour constraints.     

THE NEED FOR PHYSICAL GEOGRAPHY

As a viable intellectual and professional pursuit with well defined goals, physical geography is alive and kicking but demands greater commitment from the geography profession generally. In particular, physical geographers are exhorted to be thoroughly trained in the subject matter and methodology of their own and related disciplines, to be integrative in the acquisition, analysis and interpretation of data, to be predictive in their work, and to be proud of the role that they can play in serving society's environmental needs.     

九寨沟旅游劳工迁移微观驱动力分析

以九寨沟为案例地,运用混合研究方法探讨了九寨沟旅游劳工入迁的微观驱动力结构、过程和强度。研究发现:①入移动力呈前后动态变化。劳工移民初始入迁受职业收益、职业特性、旅游地吸引、社会资本和生活方式5种动力驱动,职业收益居首位,旅游地吸引其次;后继居留受职业收益、职业特性、旅游地吸引和社会资本4种动力驱动,旅游地吸引居首位,职业收益其次;②不同类型旅游劳工的迁移动力具有差异。初始入迁管理人员受事业发展和收入驱动显著,一线工作人员较多追求生活方式,个体业主和出租车司机更关注收入,景区人员更多受旅游地吸引。后继居留大企业员工首先被旅游地吸引,而个体业主和出租车司机更强调事业发展前景,旅游地吸引其次。     

Monitoring Controversial Environmental/Natural Resource Issues: Differential Effects of Telephone and Mail Surveys

Monitoring public opinion, especially about controversial environmental/natural resource issues, through various survey modes remains an important social science tool used by scholars, advocates, newspaper reporters, and policymakers alike. However, with this use there has been a concomitant decline in response rates. To address this problem, increased use of mixed modes of surveys has occurred. The degree to which results of different modes can be combined remains a basic question. Can findings be compared to assess changes in public views across time or differences among various regions when different modes of data collection are used? We addressed this question by assessing how two comparable samples of residents' responses to the same questions differed depending upon survey mode (telephone or mail) while controlling for sampling procedures and survey content.