对于分级布设的变形监测网其灵敏度的分析与改善     

王娟  刘水 《四川测绘》1994,17(2):51-53

本文主要就分级布设的变形监测网的灵敏度问题进行讨论，并就在实际工作中如何直接、有效地改善监测网的灵敏度提出了有益的建议．  相似文献   

温纳偏置电测深法压制表层电性不均匀体影响的研究   总被引：4，自引：1，他引：4  

岳建华  刘树才 《煤田地质与勘探》1994,22(6):51-56

巷道底板浮煤等电性不均匀体及厚度变化是造成煤矿井下电测深曲线畸变的主要因素。通过模型实验研究了温纳偏置电测保法压制浮煤等表层电性不均匀体影响的能力。用感度分析法讨论了表层电性不均匀体产生地电干扰的机制。实测结果表明，该方法改善了电测深曲线质量，有效地提高了电测深法地质应用效果。  相似文献   

Hydraulics of runoff and loess loam deposition     

J. De Ploey 《地球表面变化过程与地形》1984,9(6):533-539

On many more or less loamy soils, rill erosion is reported to start on slopes that are equal to or steeper than 2–3°; critical Froude numbers for the start of rill wash on these slopes vary between 2·0 and 3·0. This explains why colluvial deposition often occurs on slopes below 2–3°, when water spreads out at the downslope extremities of the rills. The critical hydraulic conditions for loess loam deposition were tested in the laboratory for slopes of 0·5° and 2°, applying unit-discharges (q) up to 10 cm²/s. It appeared from these experiments that for afterflow, without raindrop impact, deposition starts for critical load concentrations (c_cr) varying between several g/1 and about 60 g/l. Under rain c_cr amounts to a minimum value of 100–125 g/l and it increases when the runoff film becomes thinner. Nevertheless, deposition in pluvial runoff is also possible, as was the case during the Weichselian, according to data from quarries in Belgium and in The Netherlands. A modified Kalinske equation is proposed for c_cr prediction, with the introduction of a typical empirical coefficient C_r and considering such factors as shear stress and mean particle size. Massive sedimentation may occur when it stops raining and afterflow starts, since c_cr values are then much lower. It is shown from the Shields' diagram that loamy suspensions are more sensitive to sedimentation than sands in clear water.  相似文献   

Measurements of tropospheric OH concentrations: A comparison of field data with model predictions     

D. Perner  U. Platt  M. Trainer  G. Hübler  J. Drummond  W. Junkermann  J. Rudolph  B. Schubert  A. Volz  D. H. Ehhalt  K. J. Rumpel  G. Helas 《Journal of Atmospheric Chemistry》1987,5(2):185-216

Using long path UV absorption spectroscopy we have measured OH concentrations close to the earth's surface. The OH values observed at two locations in Germany during 1980 through 1983 range from 0.7×10⁶ to 3.2×10⁶ cm^-3. Simultaneously we measured the concentrations of O₃, H₂O, NO, NO₂, CH₄, CO, and the light non methane hydrocarbons. We also determined the photolysis rates of O₃ and NO₂. This allows calculations of OH using a zero dimensional time depdendent model. The modelled OH concentrations significantly exceed the measured values for low NO _x concentrations. It is argued that additional, so far unidentified. HO _x loss reactions must be responsible for that discrepancy.  相似文献   

变形监测网的灵敏度分析     

张正禄 《武汉大学学报(信息科学版)》1986,(3)

与一般的测量控制网相比较,变形监测网具有其自身的特点。它要求对于所要监测的变形向量具有尽可能高的灵敏度,这就导致了在变形监测网的设计中,除了考虑精度、可靠性等准则外,还要分析和考虑网的灵敏度。本文通过对变形监测网的灵敏度分析,说明监测网设计的一般方法和原则。  相似文献   

均质土坡的安全系数     

徐金明  陈文才 《上海国土资源》1995,(3):43-48

本文用变分法的基本理论的方法，推导出了均质土坡稳定性在平面应变情况下的基本方程，将简单边坡无粘性土（Ｃ＝０）与纯粘性土ψ＝０）的情况作为特例导出了相应的计算方法与计算公式，并对传统的条分法与土坡临界高度计算方法进行了讨论。  相似文献   

涡流地震检波器的理论研究     

王宝昌  董连芝  董世学 《吉林大学学报(地球科学版)》1995,(4)

根据严格的数学推演给出涡流地震检波器电压的频率响应特性、阻尼因数、位相等的正确公式；定义表征其某些基本特征的物理量；讨论了文献［１］中某些严重错误，简介了我们研制的新型涡流地震检波器的某些性能。  相似文献   

地球物理非线性反演模拟退火法的改进   总被引：33，自引：9，他引：33       下载免费PDF全文

姚姚 《地球物理学报》1995,38(5):643-650

在地球物理非线性反演方法中，模拟退火法是一种较先进的启发式蒙特卡洛（ＭｏｎｔｅＣａｒｌｏ）方法．但是，在处理实际资料时，该方法存在着计算效率不够高的缺点，有时还会失效．为此，从模拟退少法的关键问题──最低温度的选择入手，根据模拟退火法与统计力学的吉布斯－马尔柯夫（Ｇｉｂｂｓ－Ｍａｒｋｏｖ）模型之间的关系导出临界温度的近似表达式；用此式分析目标函数超曲面形状对模拟退火法计算的影响；提出利用模糊先验信息确定最低温度、改造目标函数等改进措施．  相似文献   

NUMERICAL EXPERIMENTS ON THE FORMATION OF THE EASTERN PACIFIC SUMMER MONSOON          下载免费PDF全文

Gao Lei  Li Weiliang  Wang Bin 《Acta Meteorologica Sinica》1995,9(3):257-266

In this paper,we use a two-dimensional primary equation model which contains (1) heating ofradiation,(2) heating of condensation,and (3) transfers of sensible and latent heat between air andthe underlying surface.To investigate the causes for the formation of the eastern North Pacific sum-mer monsoon,the data at 110°W are obtained and winds at underlying surface and at 200 hPa aremodified under the conditions (1) removing topography and (2) changing meridional sea surface tem-perature (SST) gradient.In the numerical modification,we find that by removing the topography,the center's location ofthe eastern North Pacific summer monsoon does not change,but the intensity of the summer monsoonis weakened.Also the onset of the summer monsoon is delayed to the end of May.The tropical east-erly jet is weakened obviously,even changes to westerly wind.On the other hand,we find that theSST gradient along 110°W influences the eastern North Pacific summer monsoon distinctly.If theSST gradient is decreased,the center of the southwest wind near 12°N does not exist any more.theintensity of the whole summer monsoon becomes very weak and the circulation pattern of the summermonsoon also changes a lot.Finally,we indicate that both topography and meridional SST gradient play important roles inthe occurrence of the eastern North Pacific summer monsoon.The meridional SST gradient is themost important factor that triggers the summer monsoon and the topography along 110°W influencesthe intensity and the onset time of the summer monsoon there mostly.  相似文献   

细颗粒石英光释光测年:简单多片再生法   总被引：30，自引：13，他引：30       下载免费PDF全文

王旭龙  卢演俦  李晓妮 《地震地质》2005,27(4):615-623

文中报道了细颗粒石英光释光测年中测量等效剂量的一种可靠技术——简单多片再生法。该技术的核心是引入单片再生法中试验剂量校正感量变化的功能,即在天然和再生多测片光释光信号测量后,再对各测片辐照以试验剂量,利用试验剂量的光释光信号响应对各测片归一化,同时校正可能发生的感量变化。从方法学上,这一技术具有以下优点1)试验剂量可以校正各测片的感量变化;2)对各测片归一化,克服了实验数据分散度的问题;3)通过对比简单多片再生法与单片再生法在测年中的表现,证实简单多片再生法可以克服单片再生法中可能发生的光释光信号的积累问题。最后,文中通过测定参考年龄样品,即洛川剖面末次冰期马兰黄土(L1)的开始堆积年龄,验证了简单多片再生法的可靠性,即在提高测量准确度和精度的同时,更节约时间  相似文献