全极化探地雷达地下管道分类识别技术   总被引：1，自引：0，他引：1  

冯晅  梁帅帅  恩和得力海  张明贺  董泽君  周皓秋  齐嘉慧  赵玮昌 《吉林大学学报(地球科学版)》2018,48(2):364-372

常规探地雷达大多数是单极化雷达,单极化雷达只能获得单极化数据,对复杂环境中管道准确快速地识别比较困难。为了解决此问题,本文采用了全极化探地雷达识别管道的方法,提取了单一管道目标、多个管道目标中任何一个管道目标和受其他目标影响的管道目标的极化属性。结果表明,全极化探地雷达技术对处于极化属性受到影响环境下的管道目标均能较好地识别。因此,全极化探地雷达能够获得更加全面的目标体极化信息,有效地解决了复杂环境中管道准确快速识别比较困难的问题。  相似文献   

Floc size variability under strong turbulence: Observations and artificial neural network modeling     

《Applied Ocean Research》2017

The flocculation of cohesive sediment in the presence of waves is investigated using high-resolution field observations and a newly-developed flocculation model based on artificial neural networks. Vertical profiles of suspended sediment concentration and turbulent intensity are estimated using measurements of current profile and acoustic backscatter. The vertical distribution of floc size is estimated using an artificial neural network (ANN) that is trained and validated using floc size measurements at one vertical level. Data analysis suggests a linear correlation between suspended sediment concentration and turbulence intensity. Observations and numerical simulations show that floc size is inversely related to sediment concentration, turbulence intensity and water temperature. The numerical results indicate that floc growth is supported by low concentration and low turbulence. In the vertical direction, mean size of flocs decreases toward the bottom, suggesting floc breakage due to increasing turbulence intensity toward the bed. A significant decrease in turbulent shear could occur within the bottom few-cm, related to increased damping of turbulence by sediment induced density stratification. The results of the numerical simulations presented here are consistent with the concept of a cohesive sediment particle undergoing aggregation-fragmentation processes, and suggest that the ANN can be a precise tool to study flocculation processes.  相似文献   

Application of advanced system identification technique to extract roll damping from model tests in order to accurately predict roll motions     

《Applied Ocean Research》2017

In this paper our previously developed advanced system identification technique [1] has been applied to extract the frequency dependent roll damping from a series of model tests run in irregular (random) waves. It is shown that this methodology accurately models the roll damping which can then be used to produce accurate predictions of the ships roll motion. These roll motion predictions are not only more accurate than the potential flow predictions but more accurate than potential flow models corrected using either empirical prediction methods [2] and even those corrected using roll damping obtained from free decay sallying experiments. This methodology has the potential to significantly improve roll motion prediction during full scale at sea trails of vessels in order to dramatically improve safety of critical operations such as helicopter landing or ship to ship cargo transfer.  相似文献   

风浪流中半潜式风机系统动力响应特性研究     

毛莹  范菊  张新曙  尤云祥 《海洋工程》2017,35(1):60-70

以三浮筒(Tri-floater)型半潜式风机系统为对象,采用时域方法,考虑垂荡板的黏性阻尼效应,研究系泊缆直径、长度、预张力和布置方式等参数对其在风浪流中动力响应特性的影响规律,提出了一种系泊参数优化方法。在此基础上,根据东海和南海三个不同水深区域百年一遇海洋环境条件,通过调整Tri-floater型浮式基础的吃水和垂荡板等参数,有效地提高了其运动响应周期,减小了其运动响应幅值。同时,根据风机浮式基础运动幅值的设计规范要求,针对三个不同水深区域特点,设计了Tri-floater型浮式基础的系泊系统。计算结果表明,改进后的Tri-floater型半潜式风机系统能满足百年一遇极端环境下的作业要求,适合于东海和南海海洋环境下海上风能资源的开发。  相似文献   

FSRU码头系泊模型实验与数值模拟研究   总被引：1，自引：0，他引：1  

周宏康  李欣  杨建民  罗勇 《海洋工程》2017,35(1):12-20

FSRU在恶劣环境条件下的作业和安全停靠性能与系泊缆张力、靠垫挤压应力、船体6自由度运动等参数有关。针对FSRU码头处海洋环境条件,进行FSRU不同装载状况的模型实验,获得FSRU的6自由度运动及其系泊载荷的动力特性。基于三维辐射和绕射理论,使用Sesam软件进行频域计算,以此为基础在相应海洋环境条件下进行时域耦合分析,获得FSRU 6自由度运动、系泊载荷、靠垫应力等参数的响应时历。结果表明:30%装载、横浪条件下FSRU的运动响应最大,系泊缆张力未达到破断值,靠垫压力超过其压缩60%时的载荷;模型实验对FSRU运动响应和系泊缆张力的预测结果可信,靠垫受力情况需要数值仿真进行辅助研究。  相似文献   

Motion and Dynamic Responses of A Semisubmersible in Freak Waves     

LI Xin  DENG Yan-fei  LI Lei  TIAN Xin-liang  LI Jun 《海洋工程》2017,(6):754-763

The present research aims at clarifying the effects of freak wave on the motion and dynamic responses of a semisubmersible. To reveal the effects of mooring stiffness, two mooring systems were employed in the model tests and time-domain simulations. The 6-DOF motion responses and mooring tensions have been measured and the 3-DOF motions of fairleads were calculated as well. From the time series, trajectories and statistics information, the interactions between the freak wave and the semisubmersible have been demonstrated and the effects of mooring stiffness have been identified. The shortage of numerical simulations based on 3D potential flow theory is presented. Results show that the freak wave is likely to cause large horizontal motions for soft mooring system and to result in extremely large mooring tensions for tight mooring system. Therefore, the freak wave is a real threat for the marine structure, which needs to be carefully considered at design stage.  相似文献   

江苏徐州城市规划区浅层地温能潜力评价及环境效益分析     

刘爱斌  翟如伟  景家俊  陶文杰 《地质与资源》2017,26(3):296-302

浅层地温能属于清洁、安全、可再生的地热资源,是国家重点支持开发利用的能源方向.徐州城市规划区总面积3157km²,主城区面积641km².通过调查规划区水文地质-工程地质钻探、热物性试验、施工钻孔热响应试验等工作手段,大致查明了规划区浅层地温能赋存的地质背景、形成条件、分布规律及地温场特征,进行浅层地温能开发利用适宜性分区,进而进行浅层地温能资源潜力评价及环境效益分析.根据评价分析结果,若徐州市城市规划区的浅层地温能资源全部开发利用,节能减排效益十分可观.  相似文献   

石膏矿区采空地面塌陷易发性分区与监测预警研究          下载免费PDF全文

刘爱斌  景佳俊  周丹  管祯  翟如伟 《中国地质调查》2017,4(6):76-82

邳州市邳北石膏矿区采空地面塌陷日益严重,为防治地质灾害,市政府于2016年进行了石膏矿区采空地面塌陷专项地质灾害防治规划。通过分析矿区已有资料、分析已发塌陷点和现场调查,阐述了采空区地面塌陷的特点与危害,并采用模糊综合评判方法对地面塌陷的易发性进行了分区。根据分区结果,结合人员密集程度,提出了区域采空区综合治理和地面塌陷地质灾害防治监测预警的措施和方法,为地质灾害防治工作提供依据。  相似文献   

华北地区水位下降是否会减缓气温上升——浅部地温影响的数值模拟分析          下载免费PDF全文

尹凤玲  张怀  石耀霖 《地球物理学报》2015,58(10):3649-3659

华北地区由于长期持续的地下水过量开采,导致了大面积地下水位大幅下降,引发地面塌陷、地下水质污染等一系列地质环境问题,这些现象早已为人们所熟知和关注.然而地下水位下降还会造成百米量级浅部地温及其梯度的变化,因此即使来自地球深部的大地热流密度没有变化,年度平均的从表浅部位通过地表实际传导进入大气的热流密度会减小,这是中外文献中尚未见讨论过的问题.我们通过数值模拟发现假定大地热流密度不变的条件下,华北数万平方公里地下水位下降会造成百米尺度内的地温降低,从而传入大气的热流密度降低40%以上,且会持续数百年以上的时间.这种长时间大范围的传导入大气的热流密度变化对环境会造成什么影响是一个十分值得关注的问题.这一预测在一定程度上得到了气象站地温观测数据的支持,但由于目前气象观测站只有3.2m深度范围内的地温资料,累计不超过5、60年,中间还有10余年的间断,而且表浅深度地温受地表多种因素的影响也较大,这些资料难以对我们关心的地下水位下降引起流入大气的热流密度变化这一问题提供直接确凿的数据来进行分析,因此今后有必要开展对地下数十乃至数百米地温进行持续精确的监测工作.  相似文献   

地震动参数速报仪的研制          下载免费PDF全文

胡星星  高孟潭  滕云田  王喜珍  李彩华  卢红娅  张旸 《地球物理学报》2015,58(3):1024-1034

在出现区域大震后,为了迅速展开有效的应急救援行动,需要及时准确了解烈度分布.目前震动图的获得有震后人工调查、震源参数计算、地震监测台网、地震烈度速报台网等几种方式,其中最有效的是在重点监护区建立烈度速报台网.但烈度速报台网建设往往沿用地震监测台网的模式,建设成本高、台站密度有限、实时数据传输量大.本文研制的地震动参数速报仪采用MEMS加速度计为测震传感器和ARM+Linux嵌入式计算机技术,具有体积小、成本小、功耗低、一体化、智能化的特点;其内置地震信息实时处理算法,能够自动判别地震事件并计算地震动参数;在实际应用中安装简便.通过大量密集布设这种小型仪器而组建的地震动参数速报网络,具有数据传输量小、分布式计算、组成的速报网络可靠性高、能够快速产出高分辨率的精细震动图等特点.  相似文献