水平定向钻岩石层穿越套管安装工艺     

宋龙进  刘保站 《岩土钻凿工程》2011,(6):9-11

在水平定向钻穿越长距离、复杂地质条件施工中,为保证穿越导向孔钻进工程的顺利进行,避免或减少钻杆在传递推力时在钻孔内产生“蛇行”弯曲、不能有效传递推力、钻进方向不易控制等不利因素,通常采用在钻机侧沿钻进方向的钻杆上加装部分套管技术。本文详细阐述了水平定向钻岩石层穿越套管安装的施工流程、安装技术措施,同时对套管的钻进、润滑、回抽等环节进行了分析,并对套管施工过程中安全注意事项提出了几点建议。  相似文献   

A numerical study on local characteristics of predetermined irregular wave trains     

Xiufeng Liang  Jianmin Yang  Jun Li 《Ocean Engineering》2011,38(4):651-657

In actual sea states, damage to offshore floating structures is usually caused by a few extreme waves or wave groups in an irregular wave train. Accurate simulation of the irregular wave trains can lay a solid foundation for understanding the local flow field and impact loads that would potentially cause such damage. This paper describes how the generation of a single extreme wave was investigated. Determination of the wave-maker motion for generating specified irregular wave trains is the key to this work. First, an experimental irregular wave train was decomposed into a certain number of small-amplitude waves. Fourier series expansion was performed to determine the amplitude and the initial phase angle of each wave component. Then a hydrodynamic transfer function was used to calculate the amplitude of the wave-maker motion associated with each wave component. Superposition was made on all the wave components to get the final wave-maker motion. During the numerical simulation, calculated horizontal velocity profiles of the extreme wave at different moments were analyzed and compared with experimental results, and a satisfactory agreement was obtained. In the simulation, VOF method was employed to capture the free surface, and a dissipation zone was used to deal with wave reflection.  相似文献   

A SF6 tracer study of horizontal mixing in Lake Constance   总被引：1，自引：1，他引：0  

Manfred Maiss  Johann Ilmberger  Axel Zenger  Karl Otto Münnich 《Aquatic Sciences - Research Across Boundaries》1994,56(4):307-328

Horizontal mixing processes in the hypolimnion of the western part of Lake Constance are studied by measuring the dispersion of a sulfur hexafluoride (SF₆) tracer plume. Only 1 liter gaseous SF₆ (STP) was released at a central hypolimnic depth of 60 m in August 1990. Over a period of 3 months the horizontal dispersion of the tracer plume was measured by 19 surveys using a new, vertically integrating sampling device. The observed horizontal dispersion is marked by strong storm-induced stirring events. Nevertheless mean turbulent diffusion coefficients for the whole period can be computed. They rise about linear from 0.7 10⁵ cm²/s to 3.0 10⁵ cm²/s with the distance from the western end of the lake. For the hypolimnion of Überlingersee, a sill-separated basin in the western part of Lake Constance, a simple budget model gives an exchange time of 67 ± 6 days with the main basin (Obersee).  相似文献   

Horizontal magnetic dipole over an inhomogeneous earth model with exponential variation of conductivity   总被引：1，自引：0，他引：1  

Nagendra P. Singh  T. Lal 《Pure and Applied Geophysics》1995,144(1):135-153

The paper outlines the formulation of the problem of calculating the electromagnetic field components due to a horizontal magnetic dipole placed over a multilayered earth model with one of the layers having exponential variation of conductivity with depth. Analytical solutions and numerical computations are performed for three-layered earth models possessing the described conductivity variation in the transition layer. It is assumed that the conduction currents dominate the displacement currents. Results presented here show the influence of the transition layer thickness and the conductivity contrast between the top and the bottom layers on electric and magnetic field components. The results show a characteristic dependence on the conductivity inhomogeneity.  相似文献   

日、月对孕震区的水平引潮力与震源机制的关系   总被引：10，自引：2，他引：10  

李延兴  许力生  胡新康  帅平  耿洪  张中伏 《地震》2001,21(1):1-6

根据计算日、月对孕震区水平引潮力方位角的表达式及美国哈佛大学提供的全球 Mw≥7.0的矩张量地震目录 ,选取了 1 980年 1月至 1 999年 1 2月全球发生的 (Mw≥ 7.0 ) 2 4 2次地震。利用地震目录中提供的地震矩张量参数 ,计算了每次地震发震应力场 P轴、T轴的方位角。同时计算了每次地震时日、月对震中区水平引潮力的方位角。将此方位角与 P轴、T轴以及二组断层面的走向进行对比分析。结果表明 ,日、月对震中区的水平引潮力方向与 P轴、T轴的方位角及二组断层面的走向互相平行或互相垂直 ,其平行或垂直的一致性非常好。平行或垂直相差在1 0°、2 0°、30°之内的发震概率分别达到了 0 .41 4、0 .736、0 .945。这个结果表明 ,日、月对孕震区的水平引潮力与大地震的发生密切相关。并进一步讨论了日、月对孕震区的水平引潮力对大地震发生的调制作用  相似文献   

用组合观测法提高γ因子精度的初步研究     

彭自正 《华南地震》1992,12(1):44-51

水平摆倾斜仪偏离起始平衡面工作时,存在有交互影响,它给观测记录带来误差,从而影响γ因子的精度。本文从理论上论证了交互影响的存在,推导出交互影响的计算公式,总结出消除交互影响的修正方法—组合观测法,并用组合观测法对南昌台倾斜固体潮γ因子的计算进行修正,得到提高γ因子精度的有意义的初步结果。  相似文献   

航空重力仪的试验   总被引：5，自引：0，他引：5  

张善言  周东明  宗杰  方明  王建弟  申建华  周百力  缪红 《地球物理学报》1990,33(1):70-76

CHZ海洋重力仪1988年装在国产Z-8直升飞机上进行了重力测量试验.在地面上空6个不同的高度上悬停进行重力测量,半小时测定6个高度上的重力.不考虑只悬停一分钟的测点1,则测量精度为±2.3mGal,5个不同高度悬停的归算重力平均值的精度为±1.1mGal,与地面重力值的偏差为-0.4mGal.  相似文献   

位涡倾向在Muifa台风路径转折中的应用   总被引：1，自引：0，他引：1  

袁敏  平凡  李国平 《大气科学》2018,42(2):281-291

利用ECMWF资料诊断分析了位涡倾向方程中的水平平流项和非绝热加热项分别在Muifa台风两次路径转折中的作用。结果表明:第一次路径转折过程中,非绝热加热项的量级比水平平流项小一个量级,水平平流项所表征的外部大尺度环流因素是第一次路径转折的主要原因;第二次路径转向过程由水平平流项和非绝热加热项共同控制,其中水平平流项控制台风的移向,非绝热加热项表征的内部非对称结构对台风转向有抑制作用。  相似文献   

大跨度连续梁CPⅢ点平面坐标修正方法探讨     

帅明明  王文庆 《北京测绘》2013,(3):19-21

使用大跨度连续梁上CPⅢ平面坐标时,应尽量与CPⅢ测量时环境条件一致。要满足环境条件尽量一致难以实现,为此需要探讨大跨度连续梁上CPⅢ点平面坐标受环境影响变化的规律,建立大跨度连续梁上CPⅢ点平面坐标受环境影响变化的数学模型,对平面坐标进行修正,从而减少测量次数。  相似文献   

Geostatistical modelling of spatial uncertainty using p -field simulation with conditional probability fields     

P. Goovaerts 《International journal of geographical information science》2013,27(2):167-178

This paper presents a variant of p-field simulation that allows generation of spatial realizations through sampling of a set of conditional probability distribution functions (ccdf) by sets of probability values, called p-fields. Whereas in the common implementation of the algorithm the p-fields are nonconditional realizations of random functions with uniform marginal distributions, they are here conditional to 0.5 probability values at data locations, which entails a preferential sampling of the central part of the ccdf around these locations. The approach is illustrated using a randomly sampled (200 observations of the NIR channel) SPOT scene of a semi-deciduous tropical forest. Results indicate that the use of conditional probability fields improves the reproduction of statistics such as histogram and semivariogram, while yielding more accurate predictions of reflectance values than the common p-field implementation or the more CPU-intensive sequential indicator simulation. Pixel values are then classified as forest or savannah depending on whether the simulated reflectance value exceeds a given threshold value. In this case study, the proposed approach leads to a more precise and accurate prediction of the size of contiguous areas covered by savannah than the two other simulation algorithms.  相似文献