Wave energy conversion under constrained wave-by-wave impedance matching with amplitude and phase-match limits     

《Applied Ocean Research》2019

This paper investigates an approach to limit the fullness of ‘tuning’ provided by wave-by-wave impedance matching control of wave energy devices in irregular waves. A single analytical formulation based on the Lagrange multiplier approach of Evans [1] is used to limit the velocity amplitude while also limiting the closeness of the phase match between velocity and exciting force. The paper studies the effect of the present technique in concurrently limiting the device velocity and the required control/actuation force. Time domain application requires wave-profile prediction, which here is based on a deterministic propagation model. Also examined in the time domain is the effect of possible violation of the displacement constraint, which for many designs implies impacts at hard stops within the power take-off mechanism. Time domain simulations are carried out for a 2-body axisymmetric converter (with physical end-stops) in sea states reported for a site off the US east coast. It is found that the approach leads to effective power conversion in the less energetic sea states, while as desired, considerable muting of the optimal response is found in the larger sea states. Under the assumptions of this work, the end-stop collisions are found to have a minor effect on the power conversion. The present approach could be used to guide the design of power take-off systems so that their displacement stroke, maximum force, and resistive and reactive power limits are well-matched to the achievable performance of a given controlled primary energy converter.  相似文献   

日照市露天开采矿山地质环境问题及恢复治理措施          下载免费PDF全文

汪继学  尹俊凯  陈鹏  张承斌 《山东国土资源》2018,34(12)

通过1∶5万矿山地质环境调查和遥感解译手段,对日照市矿山进行了全面的调查,查明各类矿山546处,主要集中在莒县和五莲县境内。除莒县刘官庄煤矿外,其余全部为露天开采矿山,主要选用直接开挖的方式,不仅破坏了地表环境,而且矿山生产活动产生的固体废弃物占用了大面积的土地。该文根据矿山地理位置及开采方式的不同,将相同类型的多个矿山划分为同一治理区,针对不同治理区的特点,采取科学有效的治理方法,建立健全矿山地质环境监督管理机制,切实解决矿山地质环境问题,改善生态环境。  相似文献   

海底底质声学原位测量电路控制系统研究     

吕斌  祁国梁  李官保  王景强  刘杰 《海洋科学》2018,42(5):32-39

介绍了一种液压驱动贯入式海底沉积声学原位测量系统的电路控制单元的研究实现过程,以及该控制单元在南海北部海底沉积声学调查中的应用。该电路控制单元以Cortex-A8处理器为核心,集成大容量FLASH存储器,与单片机接口控制板进行串口通讯,实现对声学发射采集单元和机械液压贯入单元的可视化控制和监测。基于该电路控制单元,海底底质声学原位测量系统兼具自容式和在线式两种工作模式,可自容记录或实时采集声学原位测量单元在海底的工作状态数据、海底沉积物声速和声衰减系数等声学特性数据。该声学原位测量系统的实验室联调及南海海试结果表明,使用该电路控制单元对海底底质声学测量过程的监测与控制是有效的,对精确获取海底底质的原位声学特性有重要作用,可以促进海底底质声学原位测量系统的产品化。  相似文献   

An approach for shake table performance evaluation during repair and retrofit actions     

Christopher Trautner  Yewei Zheng  John S. McCartney  Tara Hutchinson 《地震工程与结构动力学》2018,47(1):131-146

Large‐scale, servo‐hydraulic shake tables are a central fixture of many earthquake engineering and structural dynamics laboratories. Wear and component failure from frequent use may lead to control problems resulting in reduced motion fidelity, necessitating repairs and replacement of major components. This paper presents a methodology to evaluate shake table performance pre‐ and post‐repair, including the definition of important performance metrics. The strategy suggested is presented in the context of the rebuilding of a 4.9 × 3.1 m, 350‐kN‐capacity uniaxial shake table. In this case, the rebuild consisted of characterization of wear to table components, replacement of worn bearing surfaces, and replacement of hydraulic accumulators. To assess the effectiveness of the repair actions, sinusoidal and triangular waves, white noise, and earthquake histories were run on the table before and after the rebuild. The repair actions were successful in reducing the position and velocity dependence of friction, improving the ability of control algorithms to accurately reproduce earthquake motions. The maximum and average response spectral misfits in the period range of 0.1–2 seconds were reduced from approximately 50% to 15%, and from 5% to less than 2.5%, respectively.  相似文献   

基于分布式控制力矩陀螺的水下航行器轨迹跟踪控制   总被引：2，自引：0，他引：2  

黄道敏  徐瑞昆  唐国元  冯雷  刘智  徐国华 《海洋工程》2018,36(6):69-76

基于控制力矩陀螺群(CMGs)的水下航行器具有低速或零速机动的能力。采用基于分布式CMGs的水下航行器方案,并研究其水平面的轨迹跟踪控制问题。通过全局微分同胚变换将非完全对称的动力学模型解耦成标准欠驱动控制模型,并根据简化的模型构建其轨迹跟踪的误差动力学模型,将轨迹跟踪控制问题转化为误差模型镇定问题。基于一种分流神经元模型和反步法设计了系统的轨迹跟踪控制律,该控制器不需要对任何虚拟控制输入进行求导计算,且能确保跟踪误差的最终一致有界性。仿真结果表明该控制器能够实现在不依赖动力学参数先验知识的情况下对光滑轨迹的有效跟踪。  相似文献   

磁流变阻尼器的半主动控制及实时混合模拟试验研究          下载免费PDF全文

李歆  吕西林  Shirley Dyke 《世界地震工程》2018,34(4):130-135

磁流变阻尼器作为一种比较典型的半主动控制元件，具有构造简单、响应速度快、耐久性好、阻尼力大且连续可调等优点。即使地震中能源中断，磁流变阻尼器仍可以作为被动耗能装置继续工作发挥作用，可靠性高。设计合理有效的磁流变阻尼器半主动控制方法，对于整体结构的减震效果尤其重要。提出一种改进的磁流变阻尼器的半主动控制策略-改进的Bang-Bang控制策略，对装有磁流变阻尼器的减震控制3层框架结构进行了一系列的实时混合模拟试验，对多种半主动控制方法下的振动控制效果进行试验分析。试验结果表明:磁流变阻尼器对框架结构的减震效果显著，并验证了提出的磁流变阻尼器半主动控制策略的有效性。  相似文献   

基于SPE与SPATT的水体中麻痹性贝类毒素检测方法构建与应用   总被引：1，自引：0，他引：1  

张亚亚  闫国旺  吴海燕  谭志军  张志华  江涛  李玉 《海洋与湖沼》2020,51(2):298-306

为实现麻痹性贝类毒素(paralytic shellfish poisoning,PSP)的实时监控与提前预警,本研究构建了基于固相萃取技术(solid phase extraction,SPE)与固相吸附毒素跟踪技术(solid phase adsorption toxin tracking,SPATT)的水体中PSP检测方法,重点优化了吸附材料及前处理方法,评价了回收率、检出限等指标,并将方法应用于2019年春季秦皇岛山海关海域PSP消长过程的监测中,比较评估了两种方法的监控预警效果。结果表明:SPE方法选用ENVI-Carb 500mg/6mL固相萃取柱,过样体积为50mL,13种PSP组分的平均回收率为82.2%±10.0%、检出限为4.0-20.0ng/L;SPATT方法选用SP207大孔吸附树脂,洗脱时间为静置Id最佳,整体回收率约为9.2%;在实际应用中,结合产毒藻密度及贻贝富集毒素含量的变化,发现SPE方法的检测结果可实时表征海域PSP风险状况,对于贻贝中PSP的预警效果也显著优于SAPTT方法,后者不仅因监控方式相对滞后一个监测周期,且灵敏度及准确性均较差。对于秦皇岛海域,当SPE方法检测结果达到100ng STX eq/L时,该海域贻贝中PSP残留将具有潜在的食用安全风险,跟踪过程表明这一阈值可提前两周预警贻贝富集毒素含量超出我国限量标准(800μg STX eq/kg),这对于强化风险警示并制定防范措施具有积极作用。  相似文献   

无人船运动控制方法综述   总被引：1，自引：1，他引：0  

裴志远  戴永寿  李立刚  金久才  邵峰 《海洋科学》2020,44(3):153-162

为实现无人船海上自主作业,无人船运动控制的快速性、准确性以及鲁棒性亟待提高。首先从全驱动控制和欠驱动控制角度,分别概括了国内外无人船航向控制、航速控制、轨迹跟踪控制以及路径跟踪控制的主流控制方法。其次,归纳总结了处理海洋环境不确定扰动的研究进展,包括扰动的建模和消除、抑制扰动的主流方法。最后,总结了无人船运动控制现状与存在的问题,并从工程应用和理论研究两个角度对未来的研究方向进行了展望。  相似文献   

高层建筑坍塌墙体修复施工安全管理定量化控制模型研究          下载免费PDF全文

张新梁  杨顺生  孟昊杰 《地震工程学报》2019,41(4):1072-1078

为了确保震后高层建筑坍塌墙体修复工程的安全性,提出一种高层建筑震后坍塌墙体修复施工安全管理方法。结合主成分分析法与信息熵法对震后高层建筑坍塌墙体修复施工管理的控制特征量进行提取,确定模型评价指标权重;根据加权学习法对坍塌墙体修复的施工进行量化控制;通过灰阶量化评估进行约束参量分析,构建安全管理控制模型;采用管理因素模糊调度算法实现施工安全管理控制,并完成优化决策。通过仿真实验验证坍塌墙体修复施工管理控制的管理效益与累积评价百分率。分析结果表明,采用该方法进行震后高层建筑坍塌墙体修复施工管理控制的管理效益最高可达83.32%,累积管理效果回报率较高,累积评价百分率平均约为75%,能够有效提高施工过程的安全管理效能,确保施工安全。  相似文献   

Partition-coordinated control of soil and water loss for chestnut forests in the Yanshan Mountain Region,China   总被引：1，自引：0，他引：1  

Xinhui Ding  Guangquan Liu  Xiaoying Liu  Yongsheng Xie  Zhichun Yue 《国际泥沙研究》2019,34(1):58-64

Soil erosion from chestnut forests is one of the most important factors causing land degradation in the Yanshan Mountain Region. A 2-year field study was done to compare the effects on erosion of a control plot (CP), a repaired and maintained horizontal ditch built with an engineering baffle every 6?m (MP 1), and a repaired and maintained horizontal ditch built with an engineering baffle every 8?m (MP 2). The results showed that the slope runoff of chestnut forests was influenced by rainfall characteristic factors. No single rainfall characteristic factor showed dominance for hill slope runoff. The runoff reduction effect of the partition-coordinated erosion control measures (MP 1 and MP 2) was substantial for chestnut forests under high rainfall intensity conditions. However, the runoff reduction efficiency was higher under the conditions of heavy rainfall and low average rainfall intensity than for storms with higher intensity and lower total rainfall. The reduction effect of the partition-coordinated erosion control measures on the runoff and sediment yield of chestnut forest slopes was MP 2 > MP 1 > CP. The runoff reduction rate and erosion reduction rate of MP 2 reached 61.70% and 97.41%, respectively, and that for MP 1 was 54.15% and 85.31%, respectively. Therefore, after a comprehensive comparison, MP 2 was determined to be more effective for soil erosion control for a sloping chestnut forest.  相似文献