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31.
Land degradation is a global problem. Best management of degraded land can be done by evaluating the spatial variability of soil properties including chemical properties of degraded land and mapping such variations. Since, a significant portion of arable land in India is chemically degraded due to soil acidity; the present study was conducted to study the spatial variability of soil acidity (pH), electrical conductivity (EC), soil organic carbon (OC) content, exchangeable potassium (K+), calcium (Ca2+) and magnesium (Mg2+) contents in some cropped acid soils of India. A total of four hundred (one hundred from each series) representative surface (0–0.15 m depth) soil samples were collected from arable soils representing four soil series namely Hariharapur, Debatoli, Rajpora and Neeleswaram situated in Orissa, Jharkhand, Himachal Pradesh and Kerala states of India, respectively, and were analyzed. Soil acidity (pH between 3.90 and 6.45) showed a low variability, in contrast to other soil properties, which showed moderate variability. The coefficients of variation varied from 32.4 to 74.3, 31.2 to 50.9, 45.6 to 100, 71.9 to 93.0 and 59.0 to 79.8% for EC (mean between 0.05 and 0.09 dS m−1), OC (mean between 0.29 to 1.86%), exchangeable K+ (mean between 39.1 and 77.7 mg kg−1), Ca2+ (mean between 148 and 293 mg kg−1) and Mg2+ (mean between 111 and 191 mg kg−1), respectively. Soil pH and OC content were positively and significantly correlated with exchangeable K+, Ca2+ and Mg2+ content. Geostatistical analysis revealed that the best fit models were gaussian, exponential and spherical for different soil properties with moderate to strong spatial dependency. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
32.
李晨阳  蒙凤群 《植物保护》2023,49(4):108-114
了解我国松毛虫发生的空间分布格局及其驱动因子, 对松毛虫暴发的预防?控制和治理具有重要意义?本研究基于我国各行政区2004年-2012年间每年松毛虫发生面积及其寄主植物面积, 使用一般线性模型分析气候因子是否以及如何驱动我国松毛虫发生的空间分布格局?结果表明:在全国尺度上, 最暖季降水量是松毛虫发生的主要气候驱动因子, 松毛虫平均发生率与最暖季降水量显著正相关?在最暖季降水量的作用下, 我国松毛虫的发生呈现明显的空间分布格局, 最暖季降水量较高的南方和北方部分地区松毛虫发生率较高, 而降水量较低的西北和青藏地区松毛虫发生率较低?我们的研究结果可为松毛虫暴发的预防和管理工作提供指导?  相似文献   
33.
Phenotypic variation in organisms depends on the genotype and the environmental constraints of the habitat that they exploit. Therefore, for marine species inhabiting contrasting aquatic conditions, it is expected to find covariation between the shape and its spatial distribution. We studied the morphology of the head and cephalic sensory canals of the eelpout Austrolycus depressiceps (4.5–22.5 cm TL) across its latitudinal distribution in South Pacific (45°S–55°S). Geometric morphometric analyses show that the shape varied from individuals with larger snout and an extended suborbital canal to individuals with shorter snouts and frontally compressed suborbital canal. There was size variation across the sampled populations, but that size does not have a clear latitudinal gradient. Only 8% of the shape variation relates to this size variation (allometry), represented by a decrease in the relative size of the eye, and a depression of the posterior margin of the head. There were spatial differences in the shape of the head, but these differences were probably caused by allometric effects. Additionally, 2 of the canals of the cephalic lateralis pores and the head shape showed modularity in its development. This study shows that the morphology of marine fish with a shallow distribution varies across distances of hundreds of kilometers (i.e., phenotypic modulation).  相似文献   
34.
SVG based on XML is a kind of language describing 2D vector graphics.It is usability and applicability to set up WebGIS.The paper puts forward a system structure of WebGIS based on SVG,which has been applied to campus electronic map system of Chongqing University.It has been proved the method is feasibility and practicability.The paper sets forth some key techniques of implement of the system in detail: coding method of organizing SVG spatial data;generation of SVG electronic map;storage of SVG spatial data and implement of client.  相似文献   
35.
Today the information globalization is the trend of society development. The information technology has great influence not only on the mode of life and production, but also on the urban social and economic structure. In order to fit in with the change in this regard, the urban land-use distribution, residential mode, traffic pattern and so on should be changed correspondingly. Therefore, this change will lead to the development and evolution of whole urban spatial structure. In this paper, the development tendency of urban spatial structure in the information age is analyzed and some proposals on city planning and construction are put forward.  相似文献   
36.
Spatial load forecasting is a process distributing the total forecasted load to all partitioned area, and involving more spatial information and more factor influencing application of the future small area, which need a great deal of memory space and longer operation time. Rough set is new method of data analysis. It need not be provided with any advanced information except data set. But attribute reduct is its main algorithms. Division matrix approach on rough set used to reduce the attribute related to land - use decision in order to remove redundancy attribute and then the rules of small area land - use decision is distilled. The method obtained better effect and enhanced the total load forecasting efficiency.  相似文献   
37.
Aiming at the problem of representation of regions in the process of image processing, the paper presents a method applied to representation of spatial uncertain area in image based on Cloud-model. In two-dimension universe of discourse of image, the linguistic term of the polygons, which have uncertain edge, can be accomplished by relaxation iteration. The linguistic term of the polygons can be considered Cloud-core of Cloud-model. Based on the characteristics of pixels of transition region of fuzzy edge, Object-clouds of polygons can be constructed by Backward-cloud-generator. So Object-cloud can be representation model of spatial uncertain area and spatial uncertain area in image can be represented by digital characteristics of Object-cloud. Experiments testify the method. It enriches the cloud theory, and proposes a new idea for image comprehending and analyzing, especially remote sensing image.  相似文献   
38.
由于对边坡强度参数统计特性考虑不全面,使得边坡可靠性指标计算值偏小,对应的失效概率偏大,常常超过10%,设计中难以采纳,造成地基可靠度规范的制定和执行进展缓慢。以某高速公路全风化花岗岩土质高边坡为工程背景,在分析土质参数统计特性的基础上,采用极限平衡理论和蒙特卡罗模拟法,系统地分析了土质强度参数的均值不定性、变异性、相关性、区间特性和空间变化性等对边坡稳定可靠性的影响。结果表明:土性参数的各种统计特性对边坡稳定可靠性均具有不同程度的影响。可靠性指标计算值随抽样距离的减小而增加,随c或φ均值的增大而增加,随c和φ的变异系数的增大而减小,随c和φ相关系数绝对值的增大而增加,考虑区间性后可靠性指标计算值也明显变大。即变异性对边坡稳定不利,而相关性、区间性和空间变化性对边坡稳定有利。因此,准确而全面地考虑土质参数的统计特性,尤其是在参数变异性和相关性的基础上加以考虑土性参数空间变化性和区间性会更加符合工程实际,且计算结果趋于安全,有利于地基可靠度规范的推广运用和边坡工程的安全评价。  相似文献   
39.
本文通过聚集度指标(如:C、K、C_A、I、I_δ、)测定,以及Iwao’线性回归、Taylor’sS ̄2一回归和格局纹理分析,结果表明,棉花烂铃空间格而在一切密度下都呈聚集型,且聚集强度随烂铃密度的升高而增加,其空间格局的基本成分是疏松的个体群,其大小约为2~5株棉花,平均约含2.84个烂铃个体,且个体群内的个体呈随机分布,经μ检验和方差分析,双对角线5点式、棋盘式和平行跳跃式等3种取样方法均适用于棉花烂铃田间调查,尤以双对角线5点式为佳,用双对角线5点式应样法调查的最适抽样数:一般病情普查至少10个样方(每样方系5株棉花),系统测报和科研调查为20~30个样方。最后给出了棉花烂铃平均密度的零频率简易估计模型。  相似文献   
40.
为解决活体黄羽鸡表皮层黑色素分级方法成本高、效率低下、分级环境易受环境光干扰等问题,该研究探索一种基于ConvNeXt模型的黄羽鸡表皮层黑色素智能分级方法 ConvNeXt-WPCA,用于实现活体黄羽鸡表皮层黑色素智能分级。ConvNeXt-WPCA模型通过以下3点改进提高模型对黄羽鸡黑色素的识别效果:1)针对黄羽鸡黑色素图像RGB三通道内黑色素信息分布不均衡问题,改变输入图片通道权重来增强模型对黑色素特征的提取能力;2)使用部分卷积代替深度可分离卷积,减少模型计算量和内存访问次数提高对计算资源的利用率;3)引入坐标注意力机制,引导模型关注黄羽鸡胸腹部及肛门附近皮肤提升模型精度。同时,该研究还设计一种双光源图像获取装置,分别在自然光和偏振光条件下拍摄黄羽鸡样本,以减小分级结果受环境光干扰的影响,并探索偏振光在黑色素分级任务中的应用潜力。结果表明ConvNeXt-WPCA模型相较标准ConvNeXt模型,针对自然光下黄羽鸡黑色素图像数据集分级准确率提升9.68个百分点,最终达到89.03%的识别准确率,针对偏振光下黄羽鸡黑色素图像数据集分级准确率提升15.26个百分点,最终达到98.87...  相似文献   
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