ASD地面光谱仪在新疆白杨河铀矿床蚀变信息研究中的应用

新疆白杨河铀矿床是我国目前已探明的中型矿床,矿床蚀变特征的研究有助于对白杨河矿床外围及深部找矿提出更好的找矿认识。使用ASD可见光-短波红外地面光谱仪对白杨河矿床地表以及钻孔岩心进行光谱测量,发现了矿床中蚀变矿物主要有高铝绢云母、中铝绢云母、低铝绢云母、绿泥石、蒙脱石、赤铁矿、褐铁矿等。矿床地表铀矿化异常地段主要发育高铝绢云母蚀变;钻孔岩心中铀矿化富集部位蚀变矿物组合为高铝绢云母、绿泥石、赤铁矿。研究结果可为矿床外围及深部铀矿勘探提供参考与借鉴。     

Reliability analysis of soil nail internal limit states using default FHWA load and resistance models

Abstract

Reliability analyses of nail pullout, nail-in-tension, and system reliability of internal limit states are presented for both permanent and temporary soil nails that are designed using default Federal Highway Administration nail load and resistance models within traditional deterministic allowable stress design (ASD) framework. The model uncertainty, correlations between soil strength parameters, between model factor, and nominal load term, and between the two internal limit states, and influence of model factor fittings are all addressed in the analyses. This study provides a general idea of the reliability that is implicitly embedded in current ASD-based soil nail internal limit state designs.     

基于ASD地物光谱仪的两种天空光测量方法比较分析

基于AsD地物光谱仪最常用的两种天空光测量方法--标准灰板反演测量法和直接测量法同时观测广州市天空光辐亮度,采用灰色系统理论进行了两种测量结果的灰关联系数计算;分别对两种测量方法获取的辐亮度值进行直接比较和两种测量结果的灰关联系数定量比较分析.结果表明:标准板反演的天空光和不同方位、不同观测天顶角的天空光的灰关联系数有...     

中华绒螯蟹颤抖病组织病理学研究

采用常规石蜡切片技术、以正常样品作对照,对患颤抖病的中华绒整蟹不同组织进行病理学观察,旨在为颤抖病病原的确定及诊断等提供参考,同时期望加深对河蟹发病机制及死亡过程的认识。结果表明,患病河蟹的鳃、心脏、肝胰腺、腹节神经等组织器官发生了不同程度的病变,其病理特征主要表现为：细胞浊肿、变性、坏死,某些细胞的细胞核固缩、碎裂或崩解;结合前人的研究,推测鳃、心脏、肝胰腺、腹节神经是病原体感染河蟹的主要靶组织器官;河蟹具有重要生理功能的鳃、心脏、肝胰腺组织发生了严重病变,使其功能遭到破坏,这可能是导致河蟹发病死亡的病理学基础。     

Research on Bulbous Bow Optimization Based on the Improved PSO Algorithm

In order to reduce the total resistance of a hull, an optimization framework for the bulbous bow optimization was presented. The total resistance in calm water was selected as the objective function, and the overset mesh technique was used for mesh generation. RANS method was used to calculate the total resistance of the hull. In order to improve the efficiency and smoothness of the geometric reconstruction, the arbitrary shape deformation (ASD) technique was introduced to change the shape of the bulbous bow. To improve the global search ability of the particle swarm optimization (PSO) algorithm, an improved particle swarm optimization (IPSO) algorithm was proposed to set up the optimization model. After a series of optimization analyses, the optimal hull form was found. It can be concluded that the simulation based design framework built in this paper is a promising method for bulbous bow optimization.     

A spectral index for land degradation mapping using ASTER data: Application to a semi-arid Mediterranean catchment

Flagrant soil erosion in Morocco is an alarming sign of soil degradation. Due to the considerable costs of detailed ground surveys of this phenomenon, remote sensing is an appropriate alternative for analyzing and evaluating the risks of the expansion of soil degradation. In this paper, we characterize the state of land degradation in a small Mediterranean watershed using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and ground-based spectroradiometric measurements. The two visible, the near-infrared and six shortwave infrared bands of the above sensor were calibrated using ground measurements of the spectral reflectance. Field measurements were carried out in the Saboun experimental basin located in the marl soil region of the Moroccan western Rif. The study leads to the development and evaluation of a new spectral approach to express land degradation. This index called Land degradation index (LDI) is based on the concept of the soil line derived from spectroradiometric ground measurements. In this study, we compare LDI and the spectral angle mapping (SAM) approaches to assess and map land degradation. Results show that LDI provides more accurate results for mapping land degradation (Kappa = 0.79) when compared to the SAM method (Kappa = 0.61). Validation and evaluation of the results are based on the thematic maps derived from the ground data (organic matter, clay, silt and sand) by kriging, DEM, slope gradient and photointerpretation.