Landsat digital enhancements for lineament detection

Identification of lineaments has important ramifications in geology because lineaments can signify zones of both hazardous potential and economically valuable environments The synoptic view of local and regional lineament patterns by Landsat is a useful mapping technique in areas considered to be well mapped as well as in poorly mapped areas Image enhancement of digitally constructed Landsat images increases contrast and sharpness between geologic features and improves the recognition of subtle differences Five enhancement techniques are applied to Landsat digital data for lineament detection (1) mean value of all four bands, (2) principal components, (3) band ratio, (4) histogram equalization, and (5) high-pass digital filtering Of the five enhancement techniques evaluated, the principal components analysis identified the greatest number of lineaments and the greatest total length of the lineaments. All five techniques identified a significant amount of unique lineaments, which were not found by any other technique. Unique lineaments identified by each technique are combined through a composite process yielding a lineament interpretation which exceeds the detection capability of the principal components interpretation     

Magnetic evidence of anthropogenic dust deposition in urban soils of Shanghai,China

The magnetic particulates from anthropogenic activities can be detected by magnetic methods rapidly and cost-effectively. This study focused on the investigation of vertical variations in magnetic properties in soil profiles and magnetic enhancement originating in Baoshan, Shanghai. Also the feasibility of using arable and urban park soils as a new context for magnetic monitoring was explored. A combination of magnetic and scanning electron microscopic (SEM) techniques was applied to three soil profiles. Non-pedogenic magnetic enhancement in topsoil was recorded at all three sites accompanied by coarsening of magnetic grain size. The dominant magnetic properties reflect multi-domain (MD) and pseudo-stable single domain (PSD) ferrimagnetic minerals. Both of magnetic concentrations and grain size decrease with the depth, depending on the pollutant input, soil type and degree of vertical mixing. SEM images confirmed the presence of anthropogenic particulates fly-ash. It was concluded from this study that topsoil magnetic enhancement arising from atmospheric contaminants was readily identifiable in both arable fields and urban parks, thus broadening the scope of magnetic research on urban and industrial pollution.     

Optimisation of deep mixing technique by artificial neural network based on laboratory and field experiments

ABSTRACT

Ground improvement techniques are inevitable for weak soils that cannot endure the design load imposed by superstructures. Deep mixing technique (DMT) as one of these methods is promising and effective when a deep soil layer with low bearing capacity is encountered. Such deposits are quite common in the South-west of Iran where the studied site is located. In order to validate the influence of DMT on the enhancement of strength, both in-situ and laboratory tests were conducted. Afterwards, a parametric study was carried out to investigate the influence of key factors including cement content, water–cement ratio, curing time and plasticity index (PI) on the performance of DMT. In summary, a total of 192 different conditions were examined in this study by using two methods of 3D plotting and artificial neural networks (ANNs) as the optimisation tool. Results proved the importance of water–cement ratio as a key parameter in DMT. Based on the trained networks, ANN was revealed to give satisfactory predictions on the strength of an improved soil with different admixture conditions. More important, the optimisation made by ANN could determine the specific values for selected key admixture factors to reach a desired strength level with the coefficient of determination higher than 0.85.     

测井数据小波变换用于准层序研究

层序界面的识别及其内部特征是层序地层学研究的关键问题。准层序地层单元的分界面上物理性质变化明显,测井曲线表现为突变,测井数据小波变换能够表征这种突变。以东营凹陷某井为例,选取高斯小波对SP测井数据进行小波变换,得到时频色谱图和不同尺度上的小波系数曲线。选定最佳分解尺度后,依据该尺度下小波系数模极值的位置能准确识别出准层序界面。并利用测井多尺度分析方法对不同井段GR测井曲线进行分析,得到不同尺度下的低频和高频信息能够识别出准层序内部的沉积旋回类型,建立了相应的频谱响应特征。这些探索为层序界面的定量划分及其内部特征研究提供了一种新的思路。     

动高压冲击下岩石破裂机理及相变研究

用高压气体炮作为原动力,在不同的冲击应力加载条件下,加速平板飞片撞击角闪岩样品。对回收样品应用SEM、XRD及RAM谱仪进行了宏观和微观研究,确定了样品出现的破裂起始阶段应力强度以及其裂纹的扩展形态,从而对岩石样的破坏过程进行了量化研究,并阐释了裂纹形成的机理和相变的存在。实验表明,动高压冲击下岩石破裂机理及相变的研究,可为矿山开采、建筑工程等爆破及应用提供相关的理论依据。     

An improved fast level set method initialized with a combination of k-means clustering and Otsu thresholding for unsupervised change detection from SAR images

Detection of changes in synthetic aperture radar (SAR) images is an important challenge due to the effects of speckle noise on these images. In recent years, appropriate methods for SAR-based-change detection have been developed based on the level set methods (LSM). These methods need to set parameters for defining a proper initial contour. Moreover, the gradient information is only employed in the total energy of these methods for segmentation of the difference image. In this study, a novel method has been proposed for unsupervised change detection of multitemporal SAR images based on the improved fast level set method (IFLSM) initialized with a combination of k-means and Otsu techniques. The proposed method utilizes the discrete wavelet transform (DWT) fusion strategy and edge enhancement to achieve a noise-resistant difference image from the mean-ratio and log-ratio images. Afterward, the generated binary change map (CM) by applying a combination of k-means and Otsu techniques on the difference image is used as the initial contour to achieve a final CM on difference image using the IFLSM. To check advantages of the proposed method, experiments are applied on two sets of multitemporal SAR images corresponding to artificial Chitgar Lake (under reconstruction) in Tehran (Iran) taken by TerraSAR-X satellite in 2011 and 2012, and corresponding to San Pablo and Briones reservoirs in California (USA) acquired by ERS-2 satellite in 2003 and 2004. Results of proposed method were compared with results of some well-known unsupervised change detection methods. Experimental results prove the sufficiency of the proposed method in unsupervised change detection in terms of accuracy, implementation time, and computational complexity.     

小波结合幂次变换方法在边界识别中的应用

在位场数据边界识别传统方法理论的基础上,前人研究了各种场源边界增强技术来提高信噪比和定位精度,但仍然存在受噪声影响大、场源边界不够收敛等问题。本文在传统边界识别方法的基础上进行改进,利用小波变换与传统方法相结合来增强对噪声的压制能力,并且提出了幂次变换法对识别出的边界进行有效收敛。将改进方法与传统方法应用于地质体的边界识别;同时选取3种传统数值计算方法,结合模型数据、四川盆地重力异常数据及朱日和地区磁异常数据进行对比分析。结果表明：小波结合幂次变换法能够有效识别出研究区域内地质体的边界,能很好地起到压制噪声的作用;并且识别出的边界收敛,提高了边界识别的精度,在边界识别中取得了良好的效果。     

Extracts of impact breccia samples from Sudbury, Gardnos, and Ries impact craters and the effects of aggregation on C60 detection

Fullerenes have been detected in carbonaceous chondrite meteorites and in breccia samples from meteorite impact craters, but questions have been raised about contradictory results from similar samples and the sensitivities and accuracies of different analytical methods. We analyzed samples from three impact craters and detected C₆₀ in samples from several locations; we also observed differences in the detection capabilities of various analytical techniques used in the search for fullerenes. The presence of C₆₀ in rocks from the Onaping Formation of the Sudbury impact crater was confirmed. Low levels of C₆₀ were also detected for the first time in samples from the Gardnos (Norway) and Ries (Germany) impact structures.We detected C₆₀ in these samples using surface-enhanced laser desorption/ ionization (SELDI), but the related technique of microprobe laser-desorption, laser-ionization mass spectrometry (μL²MS) did not observe C₆₀ above detection limits. We attribute the absence of μL²MS signal to aggregate formation caused by phthalic acid esters, which appear to easily contaminate samples either during storage or demineralization in plastic containers. The μL²MS technique is incapable of detecting aggregated C₆₀, but aggregation does not suppress detection in SELDI. Phthalate-induced aggregation did, however, enhance SELDI detection of C₆₀ in some cases, and we suggest that this enhancement may help explain previously reported differences in C₆₀ detection from natural samples between laser desorption mass spectrometry (LDMS, a technique analogous to SELDI that has detected fullerenes in meteorite and impact breccia samples) and high-pressure liquid chromatography (HPLC). This work highlights the effects of phthalates and other indigenous compounds or contaminants on certain mass spectrometric techniques and lends support to the idea that several complementary analytical methods should be employed to investigate complex natural samples.     

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

Recent advances in borehole geophysical techniques have improved characterization of cross-hole fracture flow. The direct detection of preferential flow paths in fractured rock, however, remains to be resolved. In this study, a novel approach using nanoscale zero-valent iron (nZVI or ‘nano-iron’) as a tracer was developed for detecting fracture flow paths directly. Generally, only a few rock fractures are permeable while most are much less permeable. A heat-pulse flowmeter can be used to detect changes in flow velocity for delineating permeable fracture zones in the borehole and providing the design basis for the tracer test. When nano-iron particles are released in an injection well, they can migrate through the connecting permeable fracture and be attracted to a magnet array when arriving in an observation well. Such an attraction of incoming iron nanoparticles by the magnet can provide quantitative information for locating the position of the tracer inlet. A series of field experiments were conducted in two wells in fractured rock at a hydrogeological research station in Taiwan, to test the cross-hole migration of the nano-iron tracer through permeable connected fractures. The fluid conductivity recorded in the observation well confirmed the arrival of the injected nano-iron slurry. All of the iron nanoparticles attracted to the magnet array in the observation well were found at the depth of a permeable fracture zone delineated by the flowmeter. This study has demonstrated that integrating the nano-iron tracer test with flowmeter measurement has the potential to characterize preferential flow paths in fractured rock.     

Retrogression characteristics of landslides in fine-grained permafrost soils, Mackenzie Valley, Canada

Thirteen landslides (retrogressive thaw flows) were investigated to study the behavior of thaw retrogression in permafrost in the Mackenzie Valley, Northwest Territories (NWT), Canada. Those landslides are all in fine-grained ice-rich permafrost soils. Such landslides usually start from small-scale slope failures followed by retrogressive thaw flows when ice-rich permafrost soils are exposed to the atmosphere. The landslides were marked with survey stakes to measure their retreat rates for the thawing season of 2007. Two correlations are presented: one is between scarp wall height and retreat rate; another is between overall slope angle and retreat rate. It was found that thaw flow retrogression rate increases with increase in scarp wall height and slope angle up to a certain limit. It was also confirmed that thaw flow retrogression is not influenced by slope orientation.     

黑龙江省荣华立井壁后空洞破坏及注浆有限元分析

井壁溃沙、壁后空洞对立井的影响一直威胁着煤矿安全生产,对破坏的立井稳定性规律研究分析及处理方法备受关注。本文应用大型有限元分析软件ADINA,采用莫尔-库仑准则和拉伸破坏准则的组合并结合现场仪器原位检测模拟井壁后空洞破坏以及注浆,对荣华立井壁溃沙、壁后空洞对立井稳定性的影响和壁后注浆治理时不同注浆压力对井壁稳定性影响的基本规律进行研究,并依据分析结果制定了注浆方案。数值仿真分析表明:溃沙、空洞对井筒稳定有不利影响,并造成地表沉降;注浆压力对井筒稳定性有直接影响,当注浆压力达到一定值时,井壁竖向应力可出现拉压力,水平应力增大易导致井壁破裂。     

An investigation into contaminant transport processes through single-phase cement–bentonite slurry walls

Cement–bentonite walls are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in more conventional construction. The results from an investigation of an in situ single-phase cement–bentonite slurry wall are detailed, with particular attention paid to the role of advective and diffusive fluxes in contaminant transport.

The wall under investigation was installed, using standard methods and with a normal mix design, in August 1995 in order to contain leachates arising from ‘piggy-backing’ of an existing ‘dilute and disperse’ landfill site. In September 1998, the wall was investigated during which the top of the wall was exposed at adjacent locations allowing the drilling of three boreholes using rotary coring techniques. Core recovery and quality were high and samples obtained during coring were retained for testing in the laboratory.

The material recovered was quite strong and not treatable by conventional soil testing and preparation techniques. In addition, the material was susceptible to drying upon exposure to the atmosphere, with an accompanying loss of structure. In spite of this, meaningful laboratory tests were undertaken. Hydraulic conductivity of the samples was measured using constant flow-rate methods and the relative importance of the diffusive flux was investigated using a variety of simple techniques. The advective flux was found to be the dominant contaminant transport process. The results of the laboratory test programme are presented and placed in the context of the long-term performance of cement–bentonite slurry walls.     

基于图像融合和改进阈值的管道机器人探测图像增强方法

管道机器人探测能快速、准确和直观地识别管道结构性和功能性隐患,受管道内环境限制,探测的图像存在光照不均、对比度低和细节模糊等问题。为此,提出了一种管道机器人探测图像的增强技术。首先采用限制对比度自适应直方图均化（Contrast Limited Adaptive Histogram Equali-zation,CLAHE）和同态滤波（Homomorphic Filtering,HF）处理光照不均匀和对比度低的问题,并将2种方法结果进行融合。而后将融合的图像进行非下采样轮廓波变换（Nonsubsampled Contourlet Transform,NSCT）,并采用改进的Bayes-Shrink阈值对高频系数进行噪声去除。最后采用非线性映射函数对细节进行增强,并进行NSCT逆变换得到最终增强图像。选取5幅典型管道机器人探测图像进行增强处理,并与4种常见的图像增强技术进行对比。结果表明,基于图像融合和改进阈值的管道机器人探测图像增强技术可有效提高图像的整体和局部对比度,并有效增强图像的细节,能有效解决管道机器人探测图像存在的主要问题。      

Pure cross-anisotropy for geotechnical elastic potentials

The pure cross-anisotropy is understood as a special scaling of strain (or stress). The scaled tensor is used as an argument in the elastic stiffness (or compliance). Such anisotropy can be overlaid on the top of any elastic stiffness, in particular on one obtained from an elastic potential with its own stress-induced anisotropy. This superposition does not violate the Second Law. The method can be also applied to other functions like plastic potentials or yield surfaces, wherever some cross-anisotropy is desired. The pure cross-anisotropy is described by the sedimentation vector and at most two constants. Scaling with more than two purely anisotropic constants is shown impossible. The formulation was compared with experiments and alternative approaches. Static and dynamic calibration of the pure anisotropy is also discussed. Graphic representation of stiffness with the popular response envelopes requires some enhancement for anisotropy. Several examples are presented. All derivations and examples were accomplished using the algebra program Mathematica.

     

Masters of mudbrick: Geoarchaeological analysis of Iron Age earthen public buildings at Ashdod-Yam (Israel)

Excavations at Ashdod-Yam exposed a fortification system that features a massive mudbrick wall with large earthen ramparts laid on either side. This fortified horseshoe-shaped enclosure once surrounded what was likely a human-made harbor and an adjacent acropolis with complex earthen architecture, constructed and active during Iron Age IIB–C (eighth–seventh centuries B.C.E.). These Iron Age public structures are at the center of the current research. In this paper, we present the geoarchaeological analyses of Ashdod-Yam's earthen architecture. We applied a multidisciplinary methodology to new evidence for mudbrick manufacture with the goal of understanding the relationship between governing bodies and craftsmen. The analyses combine X-ray fluorescence, loss on ignition, environmental scanning electron microscopy, and thin-section petrography to investigate raw material procurement, manufacturing choices, and labor organization at Ashdod-Yam during Iron IIB–C. Construction techniques and the standardization of the mudbrick recipe point to a local enterprise regarding the site's public earthen architecture. Furthermore, the degree of labor organization must have been closely observed and supervised by a central political power. Thus, it is argued here that construction and maintenance of the site was carried out by the kingdom of Ashdod, either as a part of its own local initiative or on behalf of the Neo-Assyrian empire.     

基于DTS的地下连续墙接头处渗漏预测

地下连续墙作为深基坑的支护墙体,具有良好的强度和安全稳定性。但墙体的不完整性会引起渗漏问题的发生,严重影响墙体的功能。针对地下连续墙的渗漏问题,设计模型试验探索了不同加压功率、不同加压时长下不同含泥量混凝土的温升稳定情况,通过温升曲线中的异常点,可分析墙体的完整性及发生墙体渗漏情况,提出了基于分布式光纤温度感测(Distributed Temperature Sensing,DTS)技术的地下连续墙混凝土浇筑完整性检测方法及对地下连续墙接头处渗漏的预测方法。以昆明地铁四号线的深基坑地下连续墙项目为例,介绍了利用DTS监测地下连续墙渗漏的感测光缆及其布设方法,对比检测结果及现场实际渗漏情况,验证了这一方法的可行性和有效性。     

微生物无固相钻井液体系构建及其固壁作用机理研究

钻探过程中,常遇到破碎性地层,容易发生井壁失稳而诱发井下复杂事故。增强破碎块之间的胶结力,提升井壁围岩力学强度,是解决该类地层井壁失稳的有效途径之一,微生物诱导碳酸钙沉淀(MICP)技术为实现这一途径提供了很好的借鉴。为此,通过实验研究,分析了巴氏芽孢杆菌在无固相钻井液体系中的生长情况,得到适合巴氏芽孢杆菌生长的无固相钻井液,由此构建微生物无固相钻井液体系。利用岩心浸泡实验和扫描电镜(SEM)分析方法,探讨了微生物无固相钻井液体系的固壁效果及其作用机理。结果表明：巴氏芽孢杆菌在由植物胶、聚丙烯酰胺(PAM)、羧甲基纤维素钠(CMC)组成且含有培养基的无固相钻井液中的生长情况最好,经过24 h的生长,600 nm波长处的吸光值(OD600)达到1.54。故确定微生物无固相钻井液体系的配方为：0.1%植物胶+0.1%PAM+0.1%CMC+巴氏芽孢杆菌(OD600=0.8)+0.25%氯化钠+1%尿素+0.75%酪蛋白胨+0.25%大豆蛋白胨。在微生物无固相钻井液体系中添加钙源,可以获得更好的固壁效果,固结后试样的抗压强度达到0.183 MPa。该体系的固壁机理是微生物在松散颗粒间诱导生成...     

Effectiveness of deep cement mixing walls with top-down construction for deep excavations in soft clay: case study and 3D simulation

This paper presents the observed and simulated effectiveness of deep cement mixing walls created using top-down (DCM-TD) construction techniques for a deep excavation in soft Bangkok clay. The wall system consisted of four rows of 0.7-m-diameter DCM columns, and the bracing system consisted of two 0.25-m-thick basement slabs and seven temporary struts. The effectiveness of the wall system compared to that of other wall systems was evaluated using the measured results of previous case studies. A 3D numerical analysis was performed to calculate forces in the basement slabs and bending moments in the DCM wall. Finally, series of parametric analyses of both DCM-TD and deep cement mixing walls created using bottom-up (DCM-BU) construction techniques were carried out, and their results were compared to highlight the effectiveness of DCM-TD and its applicability to excavations at greater depths. The field and numerical results show that DCM-TD is more effective than DCM-BU in terms of the limitations of lateral wall movement, the bending moment in a DCM wall and the thickness of a DCM wall for various depths because of a larger system stiffness. Therefore, DCM-TD is very effective and suitable for use in potential future deep excavations in urban areas.

     

基于COSMIC数据电离层电子密度空间分布变化

天基GPS探测可以提供分布全球、高精度、高垂直分辨率的电离层观测资料, 弥补地基GPS探测受地域限制、垂直分辨率低的问题.利用COSMIC掩星2008—2011年数据,网格化统计分析了太阳活动处于不同水平下的电子密度空间分布变化,以期为分析电离层电子密度的空间扰动变化提供参考背景.研究表明,电子密度存在明显赤道异常和威德尔海异常现象,并发现随太阳活动性增强,在250~350 km高度范围电子密度赤道异常现象扩展到中纬地区,在300~500 km高度范围威德尔海异常现象不仅发生在南半球夏季,春秋季电子密度夜间值比白天也显著增强;在250~500 km高度范围,电子密度存在明显的威德尔海异常现象,并随着太阳活动性增强,异常区域地理范围扩宽.      

夯土建筑遗址表面温度变化特征及预报模型

在国内首次把红外热像仪应用于交河故城土遗址保护中,解决了土遗址表面温度测量的难题。通过对夯土建筑遗址墙体表面温度的监测,得出墙体表面温度随时间、空间的分布及变化规律。监测结果显示,太阳辐射、墙体朝向、风化程度等是影响土遗址墙体表面温度的重要因素。监测期间墙体的最高日温差达35?C,若在极端条件下则会更高,剧烈的温度变化减弱了土体强度,加剧了土遗址的劣化。在上述分析的基础上,利用回归拟合的方法,建立了夯土建筑遗址表面温度预报模型,通过气温即可计算出土遗址墙体表面的日温差,为土遗址的水热研究、盐分运移研究及其他相关研究提供数据支持。