应用曲线积分的地震勘探多缆定位算法

拖缆定位是海上拖缆地震勘探的一个关键环节,而准确的拖缆模型与定位算法是实现高精度拖缆定位的核心。现有的拖缆定位算法在多缆作业场景下存在数学模型不严密、定位网络观测值利用不充分的问题。为此,提出了一种基于曲线积分的海上地震勘探多缆定位算法。首先,利用曲线积分构建严密的拖缆数学模型;然后,推导了该模型下不同类型观测值的误差方程;最后,通过仿真和实测数据对算法进行有效性验证。实验结果表明,该算法解获得的拖缆缆形与检波点位置精度优于传统算法,其中沿测线方向定位精度优于1m,垂直测线方向精度优于3m,可满足海上地震勘探作业及后续地震波数据分析的需求。     

海洋拖缆数据检波器移动时差校正

在海洋拖缆地震数据采集中,当震源激发后,检波器不是固定的,而是随着拖缆一直在运动,检波器位置的移动会造成地震反射旅行时误差,影响后续地震数据处理的可靠性,同时降低时移地震资料匹配精度。为此,提出了一种校正检波器移动引起的旅行时误差的方法。该方法利用炮检距、船速和叠加速度计算检波器移动造成的旅行时误差,得到的校正时差是时变的,与炮检距和船速成正比,与叠加速度的平方成反比。实际资料处理结果表明,检波器移动时差校正可以改善动校正后CMP道集的拉平程度,提高速度谱的聚焦度,同时为后续地震数据处理提供高质量的数据。     

海洋地震勘探电缆断点检测器简介

海洋地震勘探电缆断点检测器的研制成功,有效地解决了海洋地震勘探电缆维修工作中不易查找断点的问题,本文简要介绍了该检测器的原理及应用。     

鸟粪影响下的紧凑型塔窗-导线空气间隙交流放电特性研究

查明鸟粪引起的紧凑型塔窗横担-导线空气间隙的放电原理,减少鸟害故障的发生,提高电力系统的安全运行。根据鸟粪电导率、粘度等各种参数,对紧凑型塔窗-导线空气间隙交流放电特性进行了模拟试验研究。结果表明:鸟粪污染引起塔窗-导线间隙的击穿电压降低约80%。为降低鸟害故障率,提出防治鸟害的有效措施。     

Influence of molecular structure on propagation of positive streamer discharge in dielectric liquids

In this paper, streamer discharges in dielectric liquids which have various molecular structures, such as a double bond or a triple bond in the molecular formula, are observed in detail for positive point polarity under the application of an impulse voltage to the point electrode. As test liquids, four straight‐chain hydrocarbon liquids—n‐hexane, n‐heptane, n‐octane, and n‐decane—are selected and in addition the influence of a double or triple bond included in their molecular formula on the propagation of positive streamers is investigated in detail by simultaneously using a high‐speed schlieren method and an LED current measurement system. Some differences in the mean propagation velocity and the propagation shape of positive streamers are evident. Their shape is mainly filamentary in test liquids including a double or triple bond. Also, positive streamer propagation is promoted in these liquids. It is thought that this is due to the effect of π bonds which have smaller bond energies than σ bonds. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 15–21, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10366     

针板缺陷下局部放电的严重程度分析

高压开关柜在输配电系统的开关控制中起着至关重要的作用,通过状态监测识别其缺陷严重程度具有重要的工程意义。根据开关柜的常见放电情形,设计了模拟尖刺放电的针板缺陷模型,通过逐步升压法研究了局部放电图谱随缺陷严重程度的变化规律,并通过简化模型定量分析了局部放电发展过程中的电荷运动和电场分布规律。结果表明,该模型可有效刻画缺陷严重程度演变的本质,并提供了一种基于局部放电图谱的判别依据。研究成果可应用于实际工程中。     

均匀场中负流注放电形成过程粒子模拟

为研究均匀场中负流注放电的形成过程,采用粒子模拟方法对平行平板间隙中均匀场作用下高电压流注放电通道的形成和发展进行模拟,获取流注形成发展过程的瞬态物理图像和流注通道中心场强的变化图像。模拟结果表明:电子崩向阳极发展过程中,头部呈辐射状发展,尾部细长,电子集中在电子崩头部,当电子崩转变为流注后,流注通道中形成非平衡等离子体,通道头部和尾部局部场强增大,流注头部存在高能电子;在流注通道内的电子数密度分布图中观察到流注通道存在明显的分叉现象,不同气压和场强下通道分叉现象存在差异;场强一定时,流注发展速度受气压影响较小;气压一定时,随着场强增大,高能电子出现时间缩短,流注发展速度明显提高,通道中电子数密度显著增大,电离程度加深。     

On-Line Measurement of Ion Density in Atmospheric Nitrogen Discharge Filaments via Radiation Signals from Plasma Oscillation

Diagnosis of the particle number density of plasma plays an important role in the understanding of plasma sources and processing.Regular radiation signals from plasma oscillation in filaments of atmospheric nitrogen discharge,which were excited by the injection of secondary electron beams during the propagation of the streamer,are employed to determine the ion density of plasma and its evolution in the filaments.Results show that the density of N_4~+ in a filament of atmospheric nitrogen discharge is of the order of 10~(13) cm~(-3).It is also found that the recombination processes play a dominant role in plasma decay,and that the ion density decreases non-monotonically with time during streamer propagation.     

Plasma propagation in single-particle packed dielectric barrier discharges: joint effects of particle shape and discharge gap

In this work, a single Al₂O₃ particle packed dielectric barrier discharge (DBD) reactor with adjustable discharge gap is built, and the influences of the particle shape (ball and column) and the residual gap between the top electrode and particle on the electrical and optical characteristics of plasma are studied. Our research confirms that streamer discharge and surface discharge are the two main discharge patterns in the single-particle packed DBD reactor. The strong electric field distortion at the top of the ball or column caused by the dielectric polarization effect is an important reason for the formation of streamer discharge. The length of streamer discharge is proportional to the size of the residual gap, but the number of discharge times of a single voltage cycle shows an opposite trend. Compared to the column, a smooth spherical surface is more conducive to the formation of large and uniform surface discharges. The surface discharge area and the discharge intensity reach a maximum when the gap is equal to the diameter of the ball. All in all, the results of this study will provide important theoretical support for the establishment of the synergistic characteristics of discharge and catalysis in plasma catalysis.