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121.
管桩因承载力高、稳定性强等优点得到了广泛应用,而在各领域服役过程中出现了竖向裂缝问题。为充分阐明管桩竖向裂缝产生的原因,并基于裂缝产生机理提供有效防治措施,提高管桩在不同环境下的使用寿命,解决由管桩开裂产生的各种工程问题。通过总结分析现有研究成果,对不同使用领域的管桩竖向裂缝的产生机理、裂缝危害、裂缝防治措施及裂缝检测技术进行综述,为管桩工程裂缝处理提供参考。  相似文献   
122.
为改善住宅小区居住环境,正确化解用地紧张与管线相互排斥的矛盾,保证管线运行安全,节约能源,首先必须搞好综合管线设计.本文从设计和施工的角度阐述了综合管线工程设计的要点及其作用.  相似文献   
123.
A new method to detect leakage in a water-filled plastic pipe is proposed. In this method, a leakage signal-signature in time domain is first captured by monitoring the Short Time Fourier Transforms (STFT) of AE (Acoustic Emission) signals over a relatively long time-interval. The captured signal is then used to find a mother wavelet (tuned wavelet) for the best signal localization in time and frequency domains. The technique for AE signal detection using tuned wavelet is then described. Practical application of the method proposed herein is then presented using a water-filled plastic pipe as a case study. Signals generated from this experimental setup are collected to identify leakage signal-signatures from other interfering signals (background, pipe natural frequency, splash and environmental noise). The results of the experiment prove that using tuned wavelet, AE events can be detected and identified precisely in time. In addition, sources of signals due to leakage and their respective energy levels can also be recognized.  相似文献   
124.
姜黎  张军  陈哲  余谦  王京华 《光谱实验室》2010,27(3):1208-1212
为了实现对输油管道上顺序输送不同牌号汽油(90#,93#,97#)时汽油间界面的区分,根据近红外光谱分析的基本原理,采用主成分分析-马氏距离(PCA-MD)模式识别方法,分析了700—1100nm波段和1100—1700nm波段3种不同牌号成品汽油的近红外光谱,并根据分析结果对汽油进行了分类。结果表明,使用1100—1700nm波段的汽油光谱分类结果较好,该方法可进一步鉴别汽油的质量。  相似文献   
125.
采用一体化安全分析程序,建立了ITER装置第一壁/包层及其主热传输系统、抑压系统的事故分析模型。对真空室内第一壁冷却剂管道双端断裂的失水事故进行计算,并选取单根冷却剂管道双端断裂和多根冷却剂管道双端断裂导致的失水事故工况进行热工水力行为的研究,分析相关系统的热力响应。分析表明,在发生第一壁冷却剂管道断裂事故后,由于冷却剂向真空室内释放,导致真空室内压力升高,之后由于抑压系统爆破盘的开启,可以有效缓解真空室内压力的升高,能够保障真空室系统满足设计限值。  相似文献   
126.
A perturbation solution of the fully developed flow through a pipe of circular cross-section, which rotates uniformly around an axis oriented perpendicularly to its own, is considered. The perturbation parameter is given by R = 2Ωa2/ν in terms of the angular velocity Ω, the pipe radius a and the kinematic viscosity ν of the fluid. The two coupled non-linear equations for the axial velocity ω and the streamfunction ? of the transverse (secondary) flow lead to an infinite system of linear equations. This system allows first the computation of a given order ?n, n ? 1, of the perturbation expansion ? = ∑ Rn?n in terms of ωn-1, the (n-1)-th order of the expansion ω = ∑ Rnωn, and of the lower orders ?1,…,?n ? 1. Then it permits the computation of ωn from ω0,…,ωn ? 1 and ?1,…,?;n. The computation starts from the Hagen–Poiseuille flow ω0, i.e. the perturbation is around this flow. The computations are performed analytically by computer, with the REDUCE and MAPLE systems. The essential elements for this are the appropriate co-ordinates: in the complex co-ordinates chosen the two-dimensional harmonic (Laplace, Δ) and biharmonic (Δ2) operators are ideally suited for (symbolic) quadratures. Symmetry considerations as well as analysis of the equations for ωn, ?n and of the boundary conditions lead to general (polynomial) formulae for these functions, with coeffcients to be determined. Their determination, order by order, implies, in complex co-ordinates, only (symbolic) differentiation and quadratures. The coefficients themselves are polynomials in the Reynolds number c of the (unperturbed) Hagen–Poiseuille flow. They are tabulated in the paper for the orders n ? 6 of the perturbation expansion.  相似文献   
127.
We develop improved correlations for two-phase flow friction factor that consider the effect of the relative velocity of the phases, based on a database that includes 2560 gas–liquid flow experiments in horizontal pipes. The database includes a wide range of operational conditions and fluid properties for two-phase friction factor correlations. We classify the experiments by liquid holdup ranges to obtain composite analytical expressions for two-phase friction factor vs. the Reynolds number by fitting logistic dose curves to the experimental data with. We compute the liquid holdup values used to classify the experimental data using correlations proposed previously. The Reynolds number is based on the mixture velocity and the liquid kinematic viscosity. The Fanning friction factor for gas–liquid is defined in term of the mixture velocity and density. Additionally, we sort the experimental data by flow regime and obtain the two-phase friction factor improved correlations for dispersed bubble, slug, stratified and annular flow for different holdup ranges. We report error estimates for the predicted vs. measured friction factor together with standard deviation for each correlation. The accuracy of the correlations developed in this study is compared with that of other 21 correlations and models widely available in the specialized literature. Since different authors use different definitions for friction factors and Reynolds numbers, we present comparisons of the predicted pressure drop for each and every data point in the database. In most cases our correlations predict the pressure drop with much greater accuracy than those presented by previous authors.  相似文献   
128.
Offshore pipelines subjected to accidental loads, such as impacts from trawl gear or anchors, may experience large global displacements from its initial position and large local strains. The axial forces set up during deformation move the pipeline back towards its initial position, thereby creating a complex local stress and strain history that may lead to fracture in the pipeline. In this study, material and component tests have been carried out on an X65 offshore pipeline material to investigate the behaviour during impact, and to observe if fracture occurs. Pipes were first impacted in a pendulum accelerator at varying velocities before they were pulled straight in a tension machine. Fracture was found in the impacted area of all the pipes. Material tests were carried out to determine the characteristics of the X65 pipeline material. A metallurgical investigation was also conducted, revealing that fracture initiated both inside the pipe wall and on the surface.  相似文献   
129.
李志国  张汝松 《科技信息》2011,(1):I0333-I0333,I0339
本文根据石灰石一石膏法湿式脱硫的特点,结合从事化工及电力行业管道设计工作经验,对脱硫管道设计标准的选择做比较。以此来推荐采用更合理的设计标准。  相似文献   
130.
在输气管线设计中,为了调整压缩机站之间的距离和增加管线的输量,常需要在管线中敷设一定长度的副管或变径管。本文从投资最省的角度出发,论述了输气管线中所需副管与变径管的投资与其直径之间的变化关系,建立了相应的数学模型。然后根据数学模型,给出了计算输气管线中所需副管与变径管最优技术参数(直径,壁厚和长度)的计算公式和方法。  相似文献   
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