晨阳路景观桥高斜度索塔施工工艺研究

桥梁工程的施工质量关系着项目整体的运行效果,因此,应重视桥梁施工质量。文章从实例出发,对高斜度索塔施工方案进行概述,分析下段现浇、上段预制、中段连接的先分段现浇和预制,再连接成整体的施工要点,旨在借助该论述,让更多人了解此技术,减少了高空作业时间,降低了施工安全风险,确保索塔混凝土外观施工质量,保证整体的施工效果,促进路桥行业的进一步发展。

高斜度井射孔配套技术研究及应用

随着油田主力油层产能逐年递减,近两年,为满足外围油田上产需求,陆续开辟了大批薄差油层开发试验区,受构造和地面条件等因素的影响,井型多以高斜度井为主;高斜度井电缆输送射孔配套技术,使枪串下速大幅提高,能够全部到达大斜度射孔井段;大斜度井管输射孔油管内泵送校深测量技术,使测量仪器全部到达大斜度测量位置;利用该技术可有效提高射孔效率,减小工人劳动强度。

激光二极管抽运单块高斜度效率环形腔单频固体激光器

对于单块结构非平面环形腔单频固体激光器,谐振腔尺寸和输出耦合面偏振膜反射系数的选取是其获得单频、高效率、高功率输出的关键。采用琼斯矩阵的方法讨论了单块激光器获得单频输出的工作原理。通过对谐振腔回路琼斯矩阵特征值的平方及特征值平方差的计算,提出了在晶体尺寸、磁场及抽运功率一定的情况下,通过对单块非平面环形腔输出耦合面偏振膜反射系数的设计来提高激光器的单频输出功率及斜度效率的方法。实验采用光纤耦合输出激光二极管(LD)纵向抽运单块激光器,当抽运功率最高用到 2 .83 W时,获得了最大 1 .20 W的1064 nm单频激光输出,斜度效率达47 .4%。

高功率全光纤光载微波信号功率放大器

为获得可应用于光载微波雷达系统的高功率双频激光源,用1 064nm窄线宽Nd∶YAG单块非平面环形腔激光器作为单频种子源,其输出分为两路,一路直接耦合入光纤,另一路经声光移频,与未移频的光束合束后获得中心频差为150 MHz、功率为20mW的双频激光.利用以半导体激光泵浦和掺Yb3+石英光纤为增益介质的3级主振荡功率放大系统对双频固体激光器输出的双频激光进行放大,获得50.3W的双频放大输出,光束质量因子为1.30,第三级主放大斜效率为74%.双频成分的幅度比、频差在放大过程中得到保持,拍频调制深度及信噪比等特性也未有恶化.双频光纤功率放大器在频差稳定和高功率输出等方面均有良好的表现.

Study on the simulation of acoustic logging measurements in horizontal and deviated wells

The conventional acoustic logging interpretation method, which is based on vertical wells that penetrate isotropic formations, is not suitable for horizontal and deviated wells penetrating anisotropic formations. This unsuitability is because during horizontal and deviated well drilling, cuttings will splash on the well wall or fall into the borehole bottom and form a thin bed of cuttings. In addition, the high velocity layers at different depths and intrinsic anisotropy may affect acoustic logging measurements. In this study, we examine how these factors affect the acoustic wave slowness measured in horizontal and deviated wells that are surrounded by an anisotropic medium using numerical simulation. We use the staggered-grid finite difference method in time domain （FDTD） combined with hybrid-PML. First, we acquire the acoustic slowness using a simulated array logging system, and then, we analyze how various factors affect acoustic slowness measurements and the differences between the effects of these factors. The factors considered are high-velocity layers, thin beds of cuttings, dipping angle, formation thickness, and anisotropy. The simulation results show that these factors affect acoustic wave slowness measurements differently. We observe that when the wavelength is much smaller than the distance between the borehole wall and high velocity layer, the true slowness of the formation could be acquired. When the wavelengths are of the same order （i.e., in the near-field scenarios）, the geometrical acoustics theory is no longer applicable. Furthermore, when a thin bed of cuttings exists at the bottom of the borehole, Fermat＇s principle is still applicable, and true slowness can be acquired. In anisotropic formations, the measured slowness changes with increments in the dipping angle. Finally, for a measurement system with specific spacing, the slowness of a thin target layer can be acquired when the distance covered by the logging tool is sufficiently long. Based on systematical simulations with different dipping angles and anisotropy in homogenous TI media, slowness estimation charts are established to quantitatively determine the slowness at any dipping angle and for any value of the anisotropic ratio. Synthetic examples with different acoustic logging tools and different elastic parameters demonstrate that the acoustic slowness estimation method can be conveniently applied to horizontal and deviated wells in TI formations with high accuracy.

随钻测量技术的发展现状和前景研究

为了拓宽随钻测量技术应用范畴,以该技术为对象展开分析。文章首先对随钻测量技术进行介绍,了解该技术的应用特点与原理,阐述其在化工领域的使用效果。其次介绍随钻测量技术发展与应用现状,明确当前国内外随钻测量技术研究成果。再次总结随钻测量技术参数设置、随钻测量技术多元化应用两个方面需要注意的要点,并且对今后技术发展方向做出展望。以随钻测量技术现有研究成果、应用经验为基础,为今后技术研发与创新奠定基础。

Configuration Optimization of Two-Rail Sliders on Dynamic Characteristic

An optimal design methodology for the configuration of two rail slider was proposed to get better dynamic performance. The taper length, taper height and the rail width of the reading/writing head are considered as design variables. The complex geometry method is utilized as the search scheme in the optimization process. Optimization results show that the new slider has better dynamic characteristics and is more stable than the original designed slider. The optimization process also demonstrates that the optimum model and optimum method is effective.

Research on High-Accuracy Programmable Timer Used in Acquiring UWB Signals

UWB signal digitization depends, to a large extent, on the accuracy of sampling time. A highaccuracy programmable timer is therefore the key to implementing UWB signal data acquisition. A high-accuracy programmable timer based on the principle of ramp generators is described in this paper. The counting range of the timer is up to 16 bits, the timing precision is 8 ps, and the equivalent sampling rate is up to 50G Hz. No other identical product has been reported so far. This timer was successfully used in the data acquisition system for geological radar signals developed by us.

Plant Species Diversity along an Altitudinal Gradient of Bhabha Valley in Western Himalaya

The present study highlights the rich species diversity of higher plants in the Bhabha Valley of western Himalaya in India. The analysis of species diversity revealed that a total of 313 species of higher plants inhabit the valley with a characteristic of moist alpine shrub vegetation. The herbaceous life forms dominate and increase with increasing altitude. The major representations are from the families Asteraceae, Rosaceae, Lamiaceae and Poaceae, suggesting thereby the alpine meadow nature of the study area. The effect of altitude on species diversity displays a hump-shaped curve which may be attributed to increase in habitat diversity at the median ranges and relatively less habitat diversity at higher altitudes. The anthropogenic pressure at lower altitudes results in low plant diversity towards the bottom of the valley with most of the species being exotic in nature. Though the plant diversity is less at higher altitudinal ranges, the uniqueness is relatively high with high species replacement rates. More than 90 % of variability in the species diversity could be explained using appropriate quantitative and statistical analysis along the altitudinal gradient. The valley harbours 18 threatened and 41 endemic species, most of which occur at higher altitudinal gradients due to habitat specificity.

Theoretical study of the effect of topographic height and width on generation of internal tides

Internal tides generated upon two-dimensional Gaussian topographies of different sizes and steepness are investigated theoretically in a numerical methodology.Compared with previous theoretical works,this model is not restricted by weak topography,but provides an opportunity to examine the influence of topography.Ten typical cases are studied using different values of height and/or width of topography.By analyzing the baroclinic velocity fields,as well as their first eight baroclinic modes,it is found that the magnitude of baroclinic velocity increases and the vertical structure becomes increasingly complex as height increases or width decreases.However,when both height and width vary,while parameter s(the ratio of the topographic slope to the characteristic slope of the internal wave ray) remains invariant,the final pattern is influenced primarily by width.The conversion rate is studied and the results indicate that width determines where the conversion rate reaches a peak,and where it is positive or negative,whereas height affects only the magnitude.High and narrow topography is considerably more beneficial to converting energy from barotropic to baroclinic fields than low and wide topography.Furthermore,parameter s,which is an important non-dimensional parameter for internal tide generation,is not the sole parameter by which the baroclinic velocity fields and conversion rate are determined.

Study on the climbing height of double solitary waves along an oblique embankment around Shantou city

Tsunamis have a severe impact on marine coastal structures.Tsunami is generally simplified as solitary wave as they propagate,and the presence of the aftermath of Tsunami is similar to a second solitary wave.Waveform evolution occurs as solitary wave propagate down a gentle slope.This paper reveals the propagation of double solitary waves and slope climbing by numerical simulation where the prototype of the embankment is around Shantou city in the Guangdong Province,China.It not only enriches the theory of solitary wave,but also has important implications for the analysis of tsunami disaster mechanism and the hydrodynamic load characteristics of structures.Based on the average Navier-Stokes equation and the VOF approach,numerical simulation results are given,including changes in the velocity field of the climbing and falling process species.The results show that the double solitary waves produce a strong reflux effect,which results in the second solitary wave climbing significantly less than the height of the first solitary wave without the influence of the current.At the same time,double solitary waves can have a much stronger effect on the embankment.