基于选权迭代法的GPS/北斗组合单点定位

介绍了GPS/北斗组合单点定位的数学模型,采用IGG-Ⅲ方案对单/双系统单点定位进行定权,并将结果与等权处理结果作比较。分析表明,对于单系统而言,GPS/北斗组合可以显著增加可用卫星数,降低pDop值,提高定位精度;无论是单系统还是组合系统,使用选权迭代法均能在一定程度上改善定位精度,提高解算成功率,且对组合定位效果更佳。     

Rock slope stability assessment using finite element based modelling – examples from the Indian Himalayas

Numerical modelling of rock slides is a versatile approach to understand the failure mechanism and the dynamics of rock slopes. Finite element slope stability analysis of three rock slopes in Garhwal Himalaya, India has been carried out using a two dimensional plane strain approach. Two different modelling techniques have been attempted for this study. Firstly, the slope is represented as a continuum in which the effect of discontinuities is considered by reducing the properties and strength of intact rock to those of rock mass. The equivalent Mohr-Coulomb shear strength parameters of generalised Hoek-Brown (GHB) criterion and modified Mohr-Coulomb (MMC) criterion has been used for this continuum approach. Secondly, a combined continuum-interface numerical method has been attempted in which the discontinuities are represented as interface elements in between the rock walls. Two different joint shear strength models such as Barton-Bandis and Patton’s model are used for the interface elements. Shear strength reduction (SSR) analysis has been carried out using a finite element formulation provided in the PHASE². For blocky or very blocky rock mass structure combined continuum-interface model is found to be the most suitable one, as this model is capable of simulating the actual field scenario.     

微型组合抗滑桩在青海西久公路某滑坡防治中的应用

使用微型组合抗滑桩结合其它工程措施治理滑坡是目前滑坡治理领域的一个新趋势,因其施工便利、压力注浆提高滑坡自身稳定性显著以及治理费用较低等优点,目前已大量应用于工程实践。以青海省西久公路某滑坡为例,在分析滑坡存在浅层和深层2个滑动带的基础上,提出采用微型组合抗滑桩结合锚拉式框架梁加固并使用仰斜排水孔的综合治理措施,通过治理后的稳定性验算和雨季暴雨的考验,证明了微型组合抗滑桩的综合措施的可行性和有效性。     

“大村庄制”合并村庄脆弱性评估——以宁夏永宁县试验区为个案

宁夏永宁县试验区内各合并村庄受到外部扰动时会表现出一定程度的脆弱性,并通过敏感性与适应力状况表达出来。基于结构方程模型原理构建合并村庄测量模型、一阶脆弱性SEM,运算处理试验区内8个合并村庄1600份有效问卷的调查数据,优化出合并村庄脆弱性评估指标,估算评估指标权重;依据优化出的脆弱性评估指标及评估指标权重构建灰色定权聚类模型,从扰动、敏感性、适应力3个维度评估合并村庄的脆弱性。结果表明:试验区内合并村庄整体上扰动效果差、敏感性较强、适应力一般。脆弱性规律为扰动效果好则敏感性弱、适应力强、脆弱性程度低,扰动效果差则敏感性较强或强、适应力一般、脆弱性程度高或较高。     

The effects of partial rootzone drying on root, trunk sap flow and water balance in an irrigated pear (Pyrus communis L.) orchard

Partial rootzone drying (PRD) means that part of the root system is watered as in full irrigation while the rest is exposed to soil drying. This practice is predicted to influence field hydrological circle. We studied the effect of this practice on soil water distribution, root and trunk sap flow, water consumption of pear trees, and capillary contribution from ground water table and water balance for three months in an irrigated orchard with a shallow ground water table. The irrigation treatments included: (a) conventional flooded irrigation (CFI), (b) fixed partial rootzone drying (FPRD), and (c) alternate partial rootzone drying (APRD). Root and trunk sap flows were monitored using a heat-pulse sap flow meter. The results showed that there were significant differences of soil water content in both sides of rootzone under partial drying. The capillary contribution from ground water table was significantly increased in APRD and FPRD when compared with CFI. More significantly, the total irrigation amount was greatly reduced, by 43.64 and 45.84%, respectively, for APRD and FPRD. The two PRD treatments used more soil-stored water while CFI had more drainage. The root sap flow on the wet side was substantially enhanced as a result of PRD, and was greater than that from same side in CFI. The trunk sap flow in FPRD and APRD was smaller than that in CFI. On average, both APRD and FPRD reduced plant daily water consumption by about 9.96 and 17.97%, respectively, when compared to CFI during the PRD period. Daily root water flow was a significant function of the reference evapotranspiration. The daily trunk water flow was also related to the reference evapotranspiration but the CFI carried more water than APRD and FPRD under the same evaporation demand, suggesting a restriction of transpirational water loss in the PRD trees. CFI needed a higher soil water content to carry the same amount of trunk flow than the PRD trees, suggesting the hydraulic conductance of roots in PRD trees enhanced, and the roots had a greater water uptake capacity than in CFI when the average soil water content in the rootzone was the same.     

北斗与GPS组合伪距单点定位精度分析

主要介绍了北斗与G PS组合单点定位时的原理和模型,根据自编程序,利用同济大学TJA站的数据进行计算及分析比较GPS伪距、北斗伪距、北斗/GPS组合伪距单点定位的精度。结果表明：北斗伪距单点定位的精度平面方向上达到3m以内,高程方向优于8 m ,满足普通导航定位的需求。北斗/G PS组合伪距单点定位精度明显优于单系统。在单系统观测条件差时,组合系统可以减少对单一系统的依赖性,而且还可以增强卫星定位的稳定性和可靠性。     

全国铀矿资源潜力评价航放数据处理与研究

全国铀矿资源潜力评价航放数据处理与研究通过对各铀成矿区带航空放射性特征分析研究,提取了与铀矿化密切相关的航放铀含量异常及高场和航放多元信息异常,总结了花岗岩型、火山岩型、碳硅泥岩型和砂岩型等4大类型铀矿的航空放射性特征及预测要素组合模式。该组合模式在铀资源潜力评价中应用效果十分显著。航放异常信息的合理组合,能有效地加强和突出与铀矿化相关的放射性异常信息及成矿环境信息,对全国铀矿资源潜力评价和铀矿普查找矿具有重要意义。     

中药治疗便秘型肠易激综合征SD大鼠的实验研究

目的：研究柴胡疏肝散合济川煎对肝郁气滞合并阳虚型便秘型肠易激综合征（IBS-C）模型大鼠的治疗效果及作用机制。方法：将56只SPF级雄性SD大鼠随机分为正常组（8只）和模型组（48只）,模型组采用冰水灌胃、限制饮水结合慢性束缚应激的方法制备肝郁气滞合并阳虚型IBS-C大鼠模型。将造模成功的大鼠随机分为模型对照组、复方聚乙二醇电解质散（PEG-EP)组、黛力新组及中药低、中、高剂量组,每组各8只。各组进行药物干预14 d。观察指标包括大鼠一般状态、糖水偏好率、旷场实验评分、内脏敏感性、小肠推进率、结肠黏膜HE染色及血清5-羟色胺( 5-HT) 、生长抑素(SS) 、血管活性肠肽（VIP）含量测定。结果：与模型对照组相比,柴胡疏肝散合济川煎能使模型大鼠的粪便粒数、粪便含水量、Bristol 分值、内脏敏感性、旷场试验评分、糖水偏好百分比、小肠推进率增加(P<0.01 或P<0.05),血清5-HT、SS含量降低(P<0.05),血清VIP含量升高（P<0.05）;与PEG-EP组、黛力新组相比,中药高剂量组大鼠血清5-HT、SS均降低(P<0.05),VIP水平升高(P<0.05)。结论：大鼠肝郁气滞合并阳虚型IBS-C模型制备成功,柴胡疏肝散合济川煎可改善模型大鼠肝郁和便秘症状,其作用机制可能与降低大鼠血清5-HT、SS含量和升高大鼠血清VIP含量有关。     

干燥箱烘焙加热法测定土壤有机质的方法改进

对土壤有机质的测定方法从消煮方式、消煮温度、消煮时间、干扰因子的去除等方面进行了改进和探讨。用土壤国家标准物质GBW07406、GBW07427、GBW07428、GBW07430和自制二级土壤参考标准物质GRD40-13验证改进后的方法,测定值与标准值吻合。对GBW07402、GBW07424各进行12次测定,相对标准偏差(RSD,n=12)分别为:2.02%;0.73%。本法的氧化校正系数=1.00,且准确度高、重现性好、无污染、操作简便,已成功应用于诸多土壤样品分析中,结果完全能达到测试质量要求,适用于测定有机质含量在15%以下的土壤样品。     

多源SAR影像区域网平差的比较研究

本文将有理函数模型(RFM)引入多源SAR遥感影像区域网平差中,并采用多种地面控制点布设方案,对基于严格几何处理模型和带像方仿射变换补偿的RFM区域网平差精度进行了对比分析.试验表明,对于多源SAR影像,在地面控制点较多且分布良好的情况下,基于严格几何处理模型的区域网平差可以获得较好的目标定位结果;基于RFM的区域网平差可以获得与基于严格几何处理模型的区域网平差几乎相当的目标定位精度,且受地面控制点分布和数量影响较小,非常适合稀疏地面控制点情况下的SAR遥感影像几何定位.