Searching for ancient gold mines in Filippoi area,Macedonia, Greece,using Worldview-2 satellite imagery

The study area is located near the town of Filippoi, north of the city of Kavala in northern Greece, known from ancient times for its rich gold mines, situated inside hydrothermal alteration zones (Fe–Mn oxide minerals). A Very High-Resolution (0.5 m pixel size) image of Worldview-2 satellite was digitally enhanced, yielding target areas of potential ore existence and lineaments. Ground-truth that followed digital image processing, revealed abandoned ancient mines, slags and ore occurrences. Also, a number of lineaments delineated on the satellite image were verified as faults.     

A filtering approach for estimating lake water quality from remote sensing data

In this paper we consider the estimation of lake water quality constituent distributions from hyperspectral remote sensing data. We present a computational approach that can be used to assimilate information from mathematical evolution models into data processing. The method is based on a reduced order iterated extended Kalman filter, and a convection–diffusion model is used to describe the movement of the water quality constituents. The performance of the technique is evaluated in a simulation study. The results show that the filter approach with an appropriate evolution model yields estimates that have better spatial and temporal resolutions than those obtained with conventional methods. Furthermore, the use of a feasible evolution model may make it possible to obtain information also on the concentrations in the lower parts of the lake.     

Cartographic Symbol Design Considerations for the Space–Time Cube

The cartographic representation of geographic phenomena in the space–time cube comes with special challenges and opportunities when compared with two-dimensional maps. While the added dimension allows the display of attributes that vary with time, it is difficult to display rapidly varying temporal data given the limited display height. In this study, we adapt 2D cyclic point symbols to construct 3D surfaces designed along a helical path for the space–time cube. We demonstrate how these complex?3D helical surfaces can display detailed data, including data reported daily over 100 years and data reported in four-hour intervals over a year. To create the point symbols, each value is plotted along the curve of a helix, with each turn of the helix representing one year or week, respectively. The model is modified by varying the radii from the time axis to all points using the attribute value, in these cases maximum daily temperature and four-hourly ridership, and then creating a triangulated surface from the resulting points. Using techniques common to terrain representation, we apply hue and saturation to the surface based on attribute values, and lightness based on relief shading. Multiple surfaces can be displayed in a space–time cube with a consistent time interval facing the viewer, and the surfaces or viewer perspective can be rotated to display synchronized variations. We see this method as one example of how cartographic design can refine or enhance operations in the space–time cube.     

Re-examining urban region and inferring regional function based on spatial–temporal interaction

Urban system is shaped by the interactions between different regions and regions planned by the government, then reshaped by human activities and residents’ needs. Understanding the changes of regional structure and dynamics of city function based on the residents’ movement demand are important to evaluate and adjust the planning and management of urban services and internal structures. This paper constructed a probabilistic factor model on the basis of probabilistic latent semantic analysis and tensor decomposition, for purpose of understanding the higher order interactive population mobility and its impact on urban structure changes. First, a four-dimensional tensor of time (T)?×?week (W)?×?origin (O)?×?destination (D) was constructed to identify the day-to-day activities in three time modes and weekly regularity of weekday/weekend pattern. Then we reclassified the urban regions based on the space clustering formed by the space factor matrix and core tensor. Finally, we further analysed the space–time interaction on different time scales to deduce the actual function and connection strength of each region. Our research shows that the application of individual-based spatial–temporal data in human mobility and space–time interaction study can help to analyse urban spatial structure and understand the actual regional function from a new perspective.     

横向受荷桩的最轻重量设计

尝试建立变截面桩的挠曲线微分方程,继而提出了变截面优化桩的概念,并给出了端承桩的一种优化算法。还以圆截面大孔径挖孔灌注桩为例,在桩顶受竖向荷载、水平横向力及弯矩作用时,进行了最轻重量设计。通过计算表明,使用变截面优化桩可使桩的体积减少30%以上。     

Multiple statistical approaches for the discrimination of mangrove species of Rhizophoraceae using transformed field and laboratory hyperspectral data

This study aims at discriminating eight mangrove species of Rhizophoraceae family of Indian east coast using field and laboratory spectra in spectral range (350–2500 nm). Parametric and non-parametric statistical analyses were applied on spectral data in four spectral modes: (i) reflectance (ii) continuum removed, (iii) additive inverse and (iv) continuum removed additive inverse. We introduced continuum removal of inverse spectra to utilize the advantage of continuum removal in reflectance region. Non-parametric test gave better separability than parametric test. Principal component analysis and stepwise discriminant analysis were applied for feature reduction and to identify optimal wavelengths for species discrimination. To quantify the separability, Jeffries–Matusita distance measure was derived. Green (550 nm), red edge (680–720 nm) and water absorption region (1470 and 1850 nm) were found to be optimal wavelengths for species discrimination. The continuum removal of additive inverse spectra gave better separability than the continuum removed spectra.     

托换桩-土钉墙组合支护结构的工作机制初探

针对新型托换桩-土钉墙组合支护结构,假定沉降大于托换桩沉降范围内的坡顶建筑物荷载全部转移至托换桩,阐述托换桩-土钉墙组合支护的工作机制,对支护结构的变形协调机制和荷载传递路径进行探讨,提出支护结构侧向变形、坡顶沉降以及托换桩沉降及内力的计算方法。参数及对比分析表明,相对传统的复合土钉墙支护,新型托换桩-土钉墙组合支护结构可以很明显地减小支护结构的变形和内力,随坡顶荷载的增加托换支护法中支护结构的内力和变形的增速明显小于复合土钉墙的内力和变形增速,随微型桩水平间距的增加支护结构的变形和内力都增加,微型桩嵌固深度的增加对支护结构的内力和变形影响较小。     

基坑悬臂支护桩双参数弹性地基杆系有限元法

对地基抗力双参数法在基坑悬臂支护桩位移和内力计算方面进行了探讨,即采用地基土抗力系数随深度按双参数非线性变化的假设,以弹性地基杆系单元模拟,支护桩则按弹性梁单元模拟。对某基坑悬臂支护桩进行数值模拟反分析表明,通过试算调整可获得适合于实际设计计算的地基抗力双参数,该法应用到福州市某基坑悬臂桩的实际分析和设计中获得了较为满意的结果,可供悬臂支护桩设计计算时参考。     

既有建筑物地下室增层开挖桩基屈曲稳定研究

既有建筑物地下室增层开挖可有效利用地下空间,是目前改善停车难问题的主要手段之一。既有建筑地下室增层开挖将改变原有桩基础的受力性状,从而可能引起原有桩基础屈曲失稳。提出一种预测地下室增层开挖既有桩基失稳的临界荷载及稳定计算长度的理论解法。首先,结合浙江饭店地下室增层开挖工程,简单介绍增层开挖方案。之后,通过Winkler弹性地基梁理论建立增层开挖工况下单桩基础桩-土体系总势能方程。最后,利用最小势能原理导得增层开挖工况下单桩基础屈曲失稳的临界荷载及稳定计算长度的表达式。在此基础上,研究了桩身临界荷载的影响因素。计算结果表明：随着半波数n的增加,既有桩基的临界荷载逐渐收敛;既有桩基的临界荷载随开挖深度的增大而急剧减小。分析结果可为类似地下室增层开挖工程的设计提供依据,减少开挖引起既有桩基础失稳隐患。     

软土路基深层搅拌桩检测方法的探讨

根据长江路三期软土路基的工程地质条件及道路工程的施工特征，分析与探讨了适用于道路工程中深层搅拌桩质量的检测方法和桩身质量的综合评价方法，通过对此道路工程中深层搅拌桩质量的检测，总结出了适合道路工程的，轻便触探结合钻探取心的，快捷、方便、可靠、经济合理的较为理想的检测方法。