轮胎与软路面相互作用导致有效不平度形成机理的探讨

该文通过理论分析与试验证提出了轮胎刚度随接地印迹不同而变化的观点，分析了在轮胎与软路面相互作用过程中，路面刚度，轮胎刚度的变化对有效不平度形成的影响。论述了有效不平度的形成机理，经试验证，所提出的软面有效不平度形成理论是基本正确的。     

路面不平度对车辆制动过程中轮胎动态性能影响的仿真分析

采用作者建立的非线性时变轮胎模型,仿真分析了路面不平度幅值及路面空间频率变化对地面附着性能的影响。得出路面不平度增大时,使路面对车轮的附着能力下降,因而使制动距离增长的结论。同时说明非线性时变轮胎模型能较真实地体现路面不平度的影响,对不平路面上车辆制动性能仿真是一个有效的轮胎力学模型     

基于优化模糊C均值聚类算法的路面不平度识别

模糊C均值(fuzzy C-mean,FCM)聚类算法具有良好的抗噪声性能,但FCM是一种局部搜索算法,易陷入局部最优,而遗传算法则具有全局优化搜索的优点。基于此该文提出了一种改进的FCM算法与遗传算法结合的聚类方法,先运用遗传算法得到聚类中心,然后用改进的FCM聚类算法得到最优解。并基于真实采集的道路谱数据,利用该算法对路面不平度进行识别。试验结果表明,改进的FCM算法与遗传算法结合的聚类算法路面识别率为94.54%,比FCM聚类算法高出4.98个百分点,比改进FCM算法高出4.67个百分点,具有更好的处理噪声数据的能力,提高了聚类的准确率和路面的识别率。     

昆山市农业土壤基本性质与重金属含量及二者的关系

研究了昆山市农业土壤基本性质和土壤中的重金属含量,并对二者的相关关系进行了分析。结果表明:昆山市农业土壤基本全为壤土,土壤pH值平均为6.50,土壤有机质平均含量为30.53g/kg,土壤CEC平均值为17.51cmol/kg,且各区之间变幅不大;昆山市主要污染重金属Cd、Pb和Hg全量大小排序基本为黄泥土>青泥土>青紫土>乌栅土;土壤重金属含量和土壤理化性质间的关系复杂,如全量As与pH值、有机质含量和全N含量呈极显著负相关,而全量Hg与土壤中有机质含量、全N含量、碱解N含量、CEC呈极显著正相关。     

区域土壤有机碳空间分布特征与尺度效应

结合当前土壤属性空间分布特征及其尺度效应研究进展和不足,综合采用变异函数理论、空间自相关理论、多重分形理论等方法从土壤有机碳(soil organic carbon,SOC)空间变异性、相关性和结构性等不同层面深入揭示不同尺度下SOC空间分布特征及其尺度效应。研究结果表明:除了15 km尺度外,基于变异函数分析的其他尺度块基比均小于50%,结构性因素占主导,结构性因素主要包括土壤亚类、土地质地、土地类型等,随机部分带来的空间变异性随着尺度的增加呈现减少趋势;不同尺度下的莫兰指数随着分离距离的增加由完全正值逐渐变小,过渡到正负交替出现的格局,最后完全变为负值,标准化统计量均大于1.96,每个尺度均具有良好的空间结构;不论是瑞利谱图,还是多重分形谱,随着尺度的增加,图谱越来越接近,研究区不同尺度下的SOC在空间上的分布是典型的分维数体;无论何种尺度,基于多重分形克里格法的实测值与预测值特异值空间吻合程度较高,特异值覆盖比率均在85%以上。联合了变异函数、空间自相关、多重分形和多重分形克里格等方法能够从空间变异性、空间相关性、空间结构性等更加深入全面地揭示研究区SOC空间分布特征。研究成果可为相对平坦农业区域土壤有机碳空间分布特征研究提供方法支撑。     

果化示范区土壤pH值的空间自相关及其主导因子

[目的]探索空间异质性较大的岩溶区的土壤pH值空间自相关尺度及其空间结构,分析影响典型岩溶区土壤pH值空间结构的主要环境因子。[方法]应用经典统计学方法与"3S"技术。[结果]不同深度土壤pH值的空间分布均存在高度的正向全局空间自相关和明显的空间聚集区,各深度土壤pH值的空间孤立区分布较少;影响不同深度土壤pH值空间分异的环境因子排序为:植被覆盖度石漠化程度地质背景。[结论]土壤pH值的空间分异受到了不同植被覆盖条件下酸性物质含量的影响。石漠化程度和地质背景对土壤pH值的影响,实质上是典型岩溶环境的综合反映。     

土壤表面灰度值与表层土壤含水量关系研究

快速准确获取表层土壤水分是土壤学、生态学及相关学科研究的基础。该研究在室内条件下,研究了5种不同土壤表面灰度值与含水量之间的关系,以期为利用土壤表面灰度值反演表层土壤含水量建立试验基础。研究结果表明:土壤在烘干过程中,含水量的变化受孔隙结构的影响;对于不同类型的土壤,土壤表面灰度值受矿物质组成和有机质含量的影响,随着土壤有机质含量的增加,同一含水量下的土壤表面灰度值降低;土壤表面灰度值与表层土壤含水量呈指数负相关关系。     

基于分形插值的三维路面重构与分析

原始精细的路面谱是研究车辆与路面耦合的重要基础,对车辆的通过性和噪声、振动及不平顺性NVH(noise,vibration and harshness)分析有重要的应用价值。为了构建与原始路面相同或相近的路面谱,利用非接触式激光路面不平度仪测量沥青路面、水泥路面、比利时路面和砂石路面的三维路面不平度;基于分形理论,采用迭代函数法重构这四种路面谱;结合路面不平度的统计特性评价指标和分形维数对四种路面的原始谱和重构谱进行评价。研究结果表明:重构前、后路面谱的平均值、标准差、峰度系数以及分形维数变化范围在±5%以内,除水泥路面的偏态系数变化范围均在±9%以内,重构路面谱与原始谱具有一致性;重构路面谱保持了原始路面的结构特性,并具有路面的细微结构。     

原子吸收测定土壤镍的测量不确定度评定研究

本文评定了火焰原子吸收测定土壤中镍含量的测量不确定度。以标准土壤样品(GSW 17401)为测试对象,通过应用火焰原子吸收法测定土壤镍含量,对其测量不确定度的来源、计算和结果表示等问题进行探讨。样品消解前处理产生的不确定度最大,标准曲线拟合测定溶液产生的不确定度其次。在测定中前处理和标准曲线拟合测定溶液应给予足够重视,以减小测量不确定度。     

暗管排水条件下土壤特性和作物产量的空间变异性分析

土壤水盐及作物参数空间结构的研究是改善农田管理水平的基础。该文对暗管排水条件下玉米试验田不同深度的土壤含水率、盐碱度及作物植株高度和产量的空间结构进行了计算和分析。试验结果显示,土壤含水率的自相关距离除在0.3～0.6 m土层为20 m外,其它深度均小于5 m。土壤电导率和钠吸附比的自相关距离随土壤深度的增加而增大,但随玉米的生长而减小,一般都小于40 m。玉米植株高度、干物质量和籽粒产量的自相关距离分别为20～25,10和22～42 m。玉米高度和产量与土壤含水率正相关而与土壤含盐量负相关。土壤盐分对玉     

Evaluating the influence of surface soil moisture and soil surface roughness on optical directional reflectance factors

Fine‐scale information on soil surface roughness (SSR) is needed for calculating heat budgets, monitoring soil degradation and parameterizing surface runoff and sediment transfer models. Previous work has demonstrated the potential of using hyperspectral, hemispherical conical reflectance factors (HCRFs) to retrieve the SSR of different soil crusting states. However, this was achieved by using dry soil surfaces, generated in controlled laboratory conditions. The primary aim of this study was therefore to test the impact that in situ variations in surface soil moisture (SSM) content had on the ability of directional reflectance factors to characterize SSR conditions. Five soil plots (20 cm × 20 cm in area) representing different agricultural conditions were subjected to different durations of natural rainfall to produce a range of different levels of SSR. The values of SSM varied from 8.7 to 20.1% across all soil plots. Point laser data (4‐mm sample spacing) were geostatistically analysed to give a spatially‐distributed measure of SSR, giving sill variance values from 3.2 to 23.0. The HCRFs from each soil state were measured using a ground‐based hyperspectral spectroradiometer for a range of viewing zenith angles from extreme forward‐scatter (θ_r = ?60°) to extreme back‐scatter (θ_r = +60°) at a 10° sampling resolution in the solar principal plane. The results showed that despite a large range of SSM values, forward‐scattered reflectance factors exhibited a very strong relationship with SSR (R² = 0.84 at θ_r = ?60°). Our findings demonstrate the operational potential of HCRFs for providing spatially‐distributed SSR measurements, across spatial extents containing spatio‐temporal variations in SSM content.     

不同地表状况耕地的田面糙率研究

田面糙率是影响田面水流运动的重要参数之一.该文针对裸地、翻耕地和作物地3种不同地表状况耕地的田面糙率进行研究.分析确定了裸地和翻耕地田面糙率的主要影响因素为田面凹凸程度,作物地田面糙率的主要影响因素还包括根茎宽度和根茎高度;进行了3种地表状况的田面凹凸程度、根茎宽度和根茎高度的田间实测及田面水流运动试验;将零惯量模型与优化方法相结合,建立了田面糙率求解的优化模型;根据田面实测资料,利用优化模型求得3种耕地的田面糙率值,据此,建立了裸地、翻耕地和作物地3种耕地田面糙率与其主要影响因素之间的关系式,验证试验结果表明,所建立的关系式正确.这对合理设计田面灌溉系统,提高灌水质量具有重要参考价值.     

激光微地貌扫描仪测定侵蚀过程中地表糙度

为研究激光微地貌扫描仪用于测定南方红壤地区地表微地貌的演变特征和规律的可行性,该研究应用亚毫米级高精度激光扫描和计算机数字图像处理相结合的方法,在野外原位研究了鄂南3个典型红壤(泥质页岩发育红壤、第四纪红黏土发育红壤1和第四纪红黏土发育红壤2)模拟降雨条件下坡面侵蚀过程中的地表糙度变化过程,初步探讨了降雨和径流对红壤坡面微地貌形态演变作用。结果表明:1)随着降雨进行,雨滴打击和径流搬运的联合作用导致地表糙度降低,间歇式降雨后,供试土壤泥质页岩发育红壤、第四纪红黏土发育红壤1和第四纪红黏土发育红壤2的地表糙度分别降低了18.2%、18.4%和11.8%;2)地表糙度变化主要发生在降雨初期,第1场降雨前后,泥质页岩发育红壤、第四纪红黏土发育红壤1和第四纪红黏土发育红壤2的地表糙度降低幅度分别为16.1%、19.7%和9.6%,均达到显著水平。采用亚毫米级高精度激光扫描和计算机数字图像处理相结合的方法,能很好地定量化研究坡面水蚀过程中地表糙度的演变特征和规律。研究为南方红壤区坡面水蚀过程中地表微地貌的研究提供一定的参考,对土壤侵蚀过程模拟与预测模型的研究具有一定的参考价值。     

Impact of Collembola and Enchytraeidae on soil surface roughness and properties

The aim of the study was to quantify the alteration of soil surface roughness caused by the casting activity of mesofauna. Undisturbed soil monoliths with a surface area of 5000mm² were taken from the upper 4cm of the Ap-horizon in agricultural land. Two tillage systems were studied: conventional tillage (CT) and conservation tillage (CS). The sampling plots were mechanically compacted by wheeling with graded loads. Sampling occurred in spring after compaction and before seeding. The soil monoliths were defaunated before inoculating one half of the monoliths with 150 individuals of Collembola (Folsomia candida) and the other half with 100 individuals of Enchytraeidae (90% Enchytraeus minutus and 10% E. lacteus). Soil surface roughness was measured using a noncontact laser scanner: before inoculation and 6 months later. Photographs show the soil surface covered with casts. Results from laser scanning show that in most cases the surface roughness increased due to mesofaunal activity. However, roughness decreased when cracks were filled with casts. The casting activity and surface roughness changes are highest in uncompacted soil. A high degree of soil compaction significantly reduced the activity at the surface. In most cases the soil surface is more altered in CT than in CS. When the content of carbon and nitrogen were determined, both elements were accumulated in the casts but more by Collembola than Enchytraeidae. The results are discussed in the context of the hemiedaphic (F. candida) and the euedaphic (Enchytraeus spp.) mode of living. Received: 6 December 1996     

近景摄影测量提高裸露地表粗糙度测量精度

微波遥感观测量对地表参数敏感,可用于对土壤水分、地表粗糙度和植被信息的定量提取。地表粗糙度参数实测值,是遥感反演结果验证、精度评价,以及各类遥感反演算法中的重要参量,但一直缺少一种简便、快捷、高精度的获取手段。该研究将近景摄影测量方法和微波遥感领域传统地表粗糙度测量的针板法进行对比,分析2种方法均方根高度及相关长度的测量结果,表明近景摄影测量法可以有效提高粗糙度实地测量精度;以近景摄影测量法全角度粗糙度参数的均值作为实测真实值,表明传统针板法测量的均方根高度误差达到12%~35.1%,相关长度误差最大能达到19.6%~62.4%;分析了采样间隔和采样数目对粗糙度测量的影响,表明针板法采用1 cm的间隔是实际地表较好的选择,但仅采用2个方向均值的测量方法必然带来很大误差,同时得出测量次数大于12时,测量结果趋于稳定并可认定为真值的结论;此外,研究表明,在一些传统针板法无法提取粗糙度的情况,近景摄影测量法依然有效。该研究表明,近景摄影测量法的非接触式、高精度、采样间隔及采样频率可调节等特征,为微波遥感工作提供了有效的地表粗糙度地面实测手段。     

Spatiotemporal variations of soil surface roughness from in-situ laser scanning

Microtopography and roughness are highly dynamic properties of the soil surface and important factors governing surface runoff and erosion processes. While various remote sensing technologies were successfully applied for topography measurements at different spatial scales, there is a lack of field studies that collected systematically microtopography data over long observation periods. In this paper an approach to measure and quantify surface roughness in the field based on laser scanning technologies is presented. Between June 2004 and November 2005 97 in-situ measurements were conducted in a test site with two different sandy substrates in vegetation-free conditions. Two-dimensional high-resolution (1 mm) datasets where generated for eight micro erosion plots of 0.25 to 2.9 m² in size. Dynamics and pattern formation were quantified for surface roughness and surface height changes. Roughness patterns at different scales were analyzed by local roughness indices using sliding windows of 3 to 55 mm in size. Results show strong spatial and temporal dynamics in surface roughness as well as substrate-specific variations. Temporal roughness variations could be detected and were linked to precipitation patterns. The methods presented in this paper are considered suitable to generate high-resolution datasets on spatiotemporal and multi-scale microtopography patterns and to advance the understanding of surface processes at small scales in natural environments.     

Characterizing soil surface roughness using a combined structural and spectral approach

The ability to quantitatively and spatially assess soil surface roughness is important in geomorphology and land degradation studies. This paper describes the results of an experiment designed to investigate whether hyperspectral directional reflectance factors can describe fine‐scale variations in soil surface roughness. A Canadian silt loam soil was sieved to an aggregate size range of 1–4.75 mm and exposed to five different artificial rainfall durations to produce soils displaying progressively decreasing levels of surface roughness. Each soil state was measured using a point laser profiling instrument at 2 mm spatial resolution, in order to provide information on the structure and spatial arrangement of soil particles. Hyperspectral directional reflectance factors were measured using an Analytical Spectral Devices FieldSpec Pro Spectroradiometer (range 350–2500 nm), at a range of measurement angles (θ_r=?60° to +60°) and illumination angle conditions (θ_i= 28°–74°). Directional reflectance factors varied with illumination and view angles, and with soil structure. Geostatistically‐derived indicators of soil surface roughness (sill variance) were regressed with directional reflectance factors. The results showed a strong relationship between directional reflectance and surface roughness (R²= 0.94 where θ_r=?60°, θ_i= 67°–74°). This fine‐scale quasi‐natural experiment allowed the control of slope, initial aggregate size and rainfall exposure, permitting an investigation into factors affecting a soil’s bidirectional reflectance response. This has highlighted the relationship between fine‐scale variations in surface roughness, illumination angle and reflectance response. The results show how the technique could provide a quantitative measure of surface roughness at fine spatial scales.     

油菜机械直播作业厢面地表粗糙度测量与分析

油菜机械直播后种床整理质量是影响油菜成苗率的关键要素。针对目前油菜机械直播种床厢面粗糙度测量和数据处理方法不能完全反映地表真实情况的现实问题,该文提出一种基于激光雷达扫描技术的区域地表粗糙度现场测量和量化方法,通过测量装置可快速获取油菜直播厢面幅宽内的地表高程三维数据。基于油菜机械直播作业特性,对采集的作业厢面高程数据进行去倾斜趋势和去边坡趋势处理,降低了厢面倾斜和边坡特征对粗糙度计算的影响。对不同空间采样间隔和不同采样角度截面数据的粗糙度统计结果表明:170 mm采样间隔下的平均均方根高度和均方根高度平均误差均高于5 mm采样间隔下的计算结果;在垂直机组前进方向0°、45°和90°三个方向上地表截面高程数据的均方根高度最大差值和相关长度最大差值分别为7.69 mm和25.14 mm,且带有种沟等结构化特征的油菜种床厢面存在明显的各向异性。以不同大小区域的滑动取样窗口进行局部粗糙度量化的统计结果表明:当窗口宽度为厢面幅宽和0.5倍时,窗口长度大小不低于1.2 m可使均方根高度的标准差稳定在0.27 mm以内,而通过对每个取样窗口进行单独去倾斜趋势处理可消除地表局部倾斜对粗糙度计算的影响。研究结果可为油菜机械直播作业厢面粗糙度测量和量化方法提供参考依据。     

A combination of laser technology and fractals to analyse soil surface roughness

Laboratory experiments were conducted on artificially weathered mudrocks (i) to measure changes in the roughness following cycles of freezing and thawing, and (ii) to find a simple method to calculate roughness as an alternative method to standard deviation methods. Surface roughness was measured with a laser profile meter and the resulting measurements were analysed by a program written for the purpose. The analysis is based on calculation of the fractal dimension of the profile for selected ranges of scale, and estimated by linear regression. Results revealed distinct micro- and macrotopographic variations of artificially weathered surface samples.     

Soil surface roughness as influenced by selected soil physical properties

Soil surface roughness affects infiltration, the storage of water in depressions on the soil surface, runoff and other processess. Roughness of soil after tillage or cultivation is affected by soil factors such as soil type, soil aggregation, water content and others. Specific soil properties that determine a soil's physical reaction to tillage should be identified, so that mechanistic relationships between those properties and the resultant roughness can be developed. The objective of this study was to determine relationships between soil surface roughness, measured using an MIF parameter (the product of a microrelief index and peak frequency), and water content, bulk density, soil texture, wet and dry aggregate size distributions, aggregate stability, organic matter content and other soil properties, measured after each of3 cultivations throughout a growing season. During the summer of 1984, soil physical properties at depths of 10.8 and 30.5 cm were measured prior to primary tillage, and at the surface immediately before 3 cultivations of soya beans, Glycine max (L.) Merr. An automated, non-contact profiler measured surface profiles along transects, 5 cm apart, of 1 × 1 m plots after each cultivation. With water content and dry bulk density at the soil surface ranging from 0.06 to 0.21 kg kg⁻¹ and from 1.05 to 1.26 Mg m⁻³, respectively, roughness, as the common logarithm of MIF, ranged from −0.758 to −0.788. Dry and wet bulk density were found to account for 64 and 52% of the variation in the MIF parameter, respectively. Water content at cultivation, and at −33 kPa, accounted for 21 and 22%, respectively, of the variation in surface roughness.