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针对电液伺服振动台单纯的以位移控制为基础存在着使用频率狭窄和系统阻尼小的缺陷而不能很好地实现波形复现的问题,本文根据地震模拟振动台振动控制系统的工作性能,在对液压系统进行一定线性化处理的基础之上,搭建了系统的数学模型.在单纯位移控制的基础上,增加了加速度和速度环节设计三参量控制器,分别用PID控制和三参量控制的方法对电液振动台进行仿真研究,比较了PID控制和三参量控制的优缺点.仿真结果表明,三参量的方法能有效地增大系统阻尼防止共振破坏,增强了系统的稳定性. 相似文献
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为了解四川德阳地下水位动态，进而分析地震前兆动态，本文设计了一个基于BP神经网络的地下水位预测系统。采用SWY-Ⅱ数字式水位仪对德阳地下水位数据进行采集。根据采集的2015年水位数据，利用BP神经网络对地下水位变化进行预测，以一年的采集数据进行训练和测试，采用3个输入节点、1个输出节点设计了BP神经网络结构。为了进一步验证本预测系统，本文对2017年7月1日—10月26日地下水位情况进行了预测。实验表明:该方案能有效实现地下水位的预测，为地震前兆工作提供可靠数据。 相似文献
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控制路基沉降是公路工程中的一个关键技术问题,而路基沉降与其影响因素之间存在着线性、非线性关系。当输入自变量较多时,用传统神经网络建模容易出现过拟合现象,导致网络模型预测精度较低。针对此问题,本文用遗传算法对神经网络模型的权值和阈值进行优化,同时讨论遗传参数的设定对输出结果的影响。通过对成南高速的实测数据进行仿真,试验结果表明:优化后的BP神经网络具有较高的预测精度,预测效果明显优于传统神经网络模型的输出结果,该预测方法可作为高速公路路基长期沉降预测的一种有效辅助手段。 相似文献
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地震模拟振动台控制系统的控制参数较多,其参数手动整定费时费力,尤其对于多振动台台阵系统,其手动整定难度很大.基于上述问题,根据专家进行系统调试的经验,提出了一种振动台控制参数自整定策略,分析了手动整定中各参数对系统性能的影响,给出了自整定算法的整定规则,并通过Matlab仿真进行振动台的控制参数自动整定.通过比较自整定参数和理论计算参数下的时频域特性,验证了本文所给出的自整定算法.结果表明,该方法具有简单实用及较好的实用价值,可供振动台参数自整定研究参考和借鉴. 相似文献
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利用神经网络算法挖掘海量数据的规律已成为科技发展的一种趋势，本文针对卫星信号的天顶对流层延迟进行建模.对流层延迟是影响卫星定位精度的重要因素之一，建立精密区域对流层模型对高精度定位有着重要的意义.对区域测站对流层延迟数据的分析，考虑到实时建模中传统BP（Back Propagation）神经网络计算量大，易出现"过拟合"现象、不稳定等因素，通过改进的BP神经网络建立了区域精密对流层模型.详细介绍了新模型的建立过程，并与常用的对流层区域实时模型进行了对比.还讨论了建模测站数目对预报精度的影响.相比现有的其他对流层延迟模型，基于改进的BP神经网络构建的区域精密对流层延迟模型无论在拟合和预报方面都有较好的精度，且随着测站数目的增加模型精度趋于平稳.改进的模型参数较少，可以进行实时的区域精密对流层延迟改正；需要播发的信息量小，适用于连续运行参考站系统（Continuously Operating Reference Stations，CORS）的应用.研究表明：改进的BP神经网络模型能够更好的充分利用大规模历史数据描述卫星信号对流层延迟的空间分布情况，适用于实时大区域精密对流层建模.基于日本地区2005年近1000多个测站的NCAR（National Center Atmospheric Research）对流层数据进行区域对流层延迟建模，结果表明改进的BP神经网络模型在拟合和预报精度上都有较大提升，RMSE（Root Mean Square Error）分别为：7.83 mm和8.52 mm，而四参数模型拟合、预报RMSE分别18.03 mm和16.60 mm. 相似文献
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地震防灾减灾能力是国家的重点需求，针对当前城市抗震应急存在的灵活性差问题，在过去研究的基础上，将GIS系统应用至城市抗震救灾应急响应中，建立的GIS系统利用地震灾害评估模块、数据库管理模块、地震应急响应和指挥决策模块构成城市抗震救灾应急响应框架，完成城市GIS系统的应用分析。地震灾害评估模块中计算震害总体损失、经济损失和生命损失，实现地震灾害评估信息数据的精确性采集；数据库管理模块中的抗灾救灾应急响应数据库主要利用矢量数据、数字正射影像数据和其他专题数据构成，完成一致性访问各种类型数据，提高城市抗震救灾应急响应灵活性；在响应与决策模块中利用核心服务器实现数据信息的上传下达，实现快速救援响应。研究中对这套GIS系统与当前方法做对比，进行抗震救灾过程灵活性、救援数据精准性的比较实验。实验对比结果表明，所提研究成果提供的救援数据精确性强，且运行过程中灵活系数等部分指标高于当前研究。 相似文献
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无人机遥感技术系统作为新时期应急救援装备是震后快速获取灾情信息的重要手段,随着无人机的智能化、轻量化的影像处理软件的迅猛发展,无人机领域的应用也越来越广泛。本文选取了辽宁大连城岭村作为实验地点,以大疆精灵4pro无人机获取的1个架次308张照片作为实验数据,选取Pix4D、smart3D、photoscan三款无人机影像处理软件,以处理流程、耗时、正射精度、三维建模等指标作为测试指标对三款软件开展对比研究工作。研究结果表明,小型消费级无人机在飞控系统下的测量精度可达厘米级,处理流程方面从简到难依次为Pix4D、photoscan、smart3D,耗时方面从短到长依次为Pix4D、photoscan、smart3D,正射(dom)精度从高到低依次为Pix4D、smart3D、photoscan,三维建模精度从高到低依次为smart3D、Pix4D、photoscan,该实验结果不仅为搭建地震应急前后方指挥部数据处理平台建设提供技术支撑,同时还对使用此类无人机做行业应用及飞行参数设置提供参考意义。 相似文献
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无人机地震灾情监测系统主要由无人机飞行平台、飞行控制系统、遥感系统、软件系统和无线电遥控系统等几部分组成,具有运行成本低、执行任务灵活性高等特点,是快速获取震后灾情信息的重要手段。结合四川高原山区的自然地理和气象条件,对无人机地震灾情监测系统在四川高原山区的应用进行了研究。该系统在高原山区的应用将在提升地震灾情现场勘查能力,迅速获取灾情信息,增加救灾工作的时效性,及为后期科学考察提供辅助信息等方面提供重要的技术支撑。 相似文献
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This paper presents a novel intelligent fuzzy weighted input estimation method which effiviently and robustly estimates the unknown ground motion accelerations. The new input estimation method includes the Kalman Filter (KF) and the recursive least square estimator (RLSE), which is weighted by the fuzzy weighting factor proposed based on the fuzzy logic inference system. By directly synthesizing the Kalman filter with the estimator, this work presents an efficient robust forgetting zone, which is capable of providing a reasonable compromise between the tracking capability and the flexibility against noises. The excellent performace of this inverse method is demonstrated by solving the earthquake-excitation estimation problem, and the proposed algorithm is compared by alternating between the constant and adaptive weighting factors. The results reveal that this method has the properties of better target tracking capability and more effective noise reduction. 相似文献
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Seismic response analysis of an interacting curved bridge–train system under frequent earthquakes 
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下载免费PDF全文 This paper establishes a scheme for the seismic analysis of interacting vehicle–bridge systems. The focus is on (horizontally) curved continuous railway bridges and frequent earthquakes. Main features of the proposed scheme are (i) the treatment of the dynamics in all three dimensions (3D), employing an additional rotating system of reference to describe the dynamics of the vehicles and a realistic 3D bridge model; (ii) the simulation of the creep interaction forces generated by the rolling contact between the wheel and the rail; and (iii) the integration of the proposed scheme with powerful commercial finite element software, during the pre‐processing and post‐processing phases of the analysis. The study brings forward the dynamics of a realistic vehicle–bridge (interacting) system during seismic shaking. For the (vehicle–bridge) case examined, the results verify the favorable damping effect the running vehicles have on the vibration of the deck. By contrast, the study stresses the adverse influence of the earthquake‐induced bridge vibration on the riding comfort but, more importantly, on the safety of the running vehicles. In this context, the paper unveils also a vehicle–bridge–earthquake timing problem, behind the most critical vehicle response, and underlines the need for a probabilistic treatment. Among the 20 sets of historic records examined, the most crucial for the safety of the vehicles are near‐fault ground motions. Finally, the study shows that even frequent earthquakes, of moderate intensity, can threaten the safety of vehicles running on bridges during the ground motion excitation, in accordance with recorded accidents. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Narutoshi Nakata 《地震工程与结构动力学》2013,42(2):261-275
Effective force testing (EFT) is one of the force‐based experimental methods used for performance evaluation of structures that incorporate dynamic force control using hydraulic actuators. Although previous studies have shown successful implementations of force control, controllable frequency ranges are limited to low frequencies (10 Hz). This study presents the EFT method using a robust loop shaping force feedback controller that can extend the frequency range up to 25 Hz or even higher. Unlike the conventional PID controllers, loop shaping controllers can provide robustness for a high level of force measurement noise. This study investigates the dynamic properties of hydraulic actuators and the design of a loop shaping controller that compensates for control–structure interaction and suppresses the effect of oil‐column resonance. The designed loop shaping controller was successfully implemented into an EFT setup at the Johns Hopkins University. An experimental investigation of the loop shaping controller was performed under step, random, and earthquake force loadings. Experimental results showed that the loop shaping controller provided excellent force tracking performance and robustness for dynamic force loadings. It was also shown that the loop shaping controller had the gain margin of 9.54 dB at the frequency of 28 Hz. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Development of high‐performance shake tables using the hierarchical control strategy and nonlinear control techniques 下载免费PDF全文
下载免费PDF全文 Conventional shake tables employ linear controllers such as proportional‐integral‐derivative or loop shaping to regulate the movement. However, it is difficult to tune a linear controller to achieve accurate and robust tracking of different reference signals under payloads. The challenges are mainly due to the nonlinearity in hydraulic actuator dynamics and specimen behavior. Moreover, tracking a high‐frequency reference signal using a linear controller tends to cause actuator saturation and instability. In this paper, a hierarchical control strategy is proposed to develop a high‐performance shake table. A unidirectional shake table is constructed at the University of British Columbia to implement and evaluate the proposed control framework, which consists of a high‐level controller and one or multiple low‐level controller(s). The high‐level controller utilizes the sliding mode control (SMC) technique to provide robustness to compensate for model nonlinearity and uncertainties experienced in experimental tests. The performance of the proposed controller is compared with a state‐of‐the‐art loop‐shaping displacement‐based controller. The experimental results show that the proposed hierarchical shake table control system with SMC can provide superior displacement, velocity and acceleration tracking performance and improved robustness against modeling uncertainty and nonlinearities. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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为适应新时期科技人员和管理人员对陆海联测指挥部技术系统的自动化、智能化监控要求，以提升指挥部技术系统监控和管理水平为目标，在历年陆海联测的基础上，设计并实现基于ONVIF协议的可移动监控系统。利用视频编码器将指挥部技术系统的输出信号转换为ONVIF协议的标准视频流，通过局域网接入硬盘录像机，最终在移动终端上安装硬盘录像机客户端，进而实现对指挥部技术系统的可移动监控。在实际灾害应急救援过程中，可为应急指挥与辅助决策人员，特别是前方决策人员提供各类技术系统信息，便于采取高效准确的救援措施，提高灾害处置能力，最大限度地减轻灾害造成的人员伤亡和经济损失。 相似文献
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Anti-ram bollard systems, which are installed around buildings and infrastructure, can prevent unauthorized vehicles from entering, maintain distance from vehicle-borne improvised explosive devices (VBIED) and reduce the corresponding damage. Compared with a fixed bollard system, a removable bollard system provides more flexibility as it can be removed when needed. This paper first proposes a new type of K4-rated removable anti-ram bollard system. To simulate the collision of a vehicle hitting the bollard system, a finite element model was then built and verified through comparison of numerical simulation results and existing experimental results. Based on the orthogonal design method, the factors influencing the safety and economy of this proposed system were examined and sorted according to their importance. An optimal design scheme was then produced. Finally, to validate the effectiveness of the proposed design scheme, four dynamic impact tests, including two front impact tests and two side impact tests, have been conducted according to BSI Specifications. The residual rotation angles of the specimen are smaller than 30º and satisfy the requirements of the BSI Specification. 相似文献
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地震是群灾之首。基层是发挥政府职能、加强危机管理、大力推进地震应急救援能力建设、防范化解地震灾害风险的重要基础。本文结合我国地震应急救援发展与基层地震应急救援管理工作，阐述了凉山州地震应急救援管理工作实践。四川凉山，立足“防大震、抢大险、救大灾”，开展地震灾害风险管理，提高地震应急救援能力，初步形成了以法制体制机制建设促进地震应急救援管理，以地震应急救援管理振兴防震减灾事业，全面推进民族团结进步的新格局。 相似文献