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31.
The Archimedes Wave Swing (AWS) pilot plant, rated at 2 MW, was tested offshore at Póvoa de Varzim in northern Portugal in 2004, gathering a large team of engineers and scientists. The Mechanical Engineering Department of Instituto Superior Técnico was involved, following previous work done for the project. The present paper describes one of the studies conducted. It aims to characterise the sea state at the actual location of the pilot plant using the available pressure sensors. Two approaches were performed: a first one purely based in linear wave theory, neglecting the presence of the device, and a second one, based on the results from a Boundary Element Method (BEM) code named AQUADYN, originally developed at École Centrale de Nantes (France), which allowed a detailed quantification of the effects of the presence of the plant on the wave profile directly above it. Comparisons with a Datawell Waverider buoy located at a certain distance from the plant also played an important role in the current study. 相似文献
32.
Eyal Levenberg 《国际地质力学数值与分析法杂志》2013,37(9):1016-1033
The paper deals with inferring the mechanical layer properties of pavement systems by way of inverse analysis. The proposed scheme is based on the availability of sensory gear embedded within the system ‐ collecting different types of response traces resulting from moving wheel loads. The inverse analysis task simultaneously exploits the readings from all available sensors and therefore formulated as a multicriterion optimization problem. Data from an experimental asphalt pavement are employed to demonstrate the scheme. A versatile and computationally efficient layered viscoelastic pavement model is offered and implemented as a forward solver. Recoverable layer properties, elastic and viscoelastic, are derived and also compared with laboratory values. Results and possible future uses of the work are discussed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
33.
本文对容性支节加载的小型化超表面天线进行了分析与设计.通过在方形贴片上引入一对容性负载支节,可以有效地降低超表面单元的工作频率,从而将传统方形贴片超表面单元的尺寸减小55%.在单元设计的基础上,设计了一款4×4阵列的超表面天线,并采用特征模分析(CMA)解释了超表面天线的辐射机制.为了验证设计思路,对天线进行了加工和测试,测量的-10 dB阻抗带宽为21.7%,并在工作频带内保持6 dBi的辐射增益. 相似文献
34.
TIAN Qiguo JIANG Peng WU Xiaoqing JIN Xinmiao LU Shan JI Tuo CHAI Bo ZHANG Shaohua ZHOU Hongyan 《极地研究(英文版)》2015,(2)
This is the second paper of a series devoted to atmospheric optical turbulence Cn2 observation using a mobile polar atmospheric parameter measurement system. We present the initial results of Cn2 measu... 相似文献
35.
Elizabeth A. Bagshaw Stephen Burrow Jemma L. Wadham James Bowden Ben Lishman Mike Salter Richard Barnes Peter Nienow 《水文研究》2012,26(20):3157-3160
This briefing describes the first deployment of a new electronic tracer (E‐tracer) for obtaining along‐flowpath measurements in subsurface hydrological systems. These low‐cost, wireless sensor platforms were deployed into moulins on the Greenland Ice Sheet. After descending into the moulin, the tracers travelled through the subglacial drainage system before emerging at the glacier portal. They are capable of collecting along‐flowpath data from the point of injection until detection. The E‐tracers emit a radio frequency signal, which enables sensor identification, location and recovery from the proglacial plain. The second generation of prototype E‐tracers recorded water pressure, but the robust sensor design provides a versatile platform for measuring a range of parameters, including temperature and electrical conductivity, in hydrological environments that are challenging to monitor using tethered sensors. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
36.
GPS车载导航系统中的航位推算技术 总被引:3,自引:0,他引:3
在车载导航系统中,相对准确地定位是实现导航的基础和前提。DR系统可以有效补充GPS的不足,是最为常用的定位系统之一。讨论了如何合理地选取DR的传感器件,并在此基础上,研究传感器件的噪声特性和组合导航的原理和方式,为自主车载导航系统的设计提供指导。 相似文献
37.
M. P. Limongelli 《地震工程与结构动力学》2003,32(7):1055-1074
In this paper, a criterion is proposed for the choice of the optimal location of a limited number of recording sensors for reconstruction of seismic responses of multistorey frames. Reconstruction of unknown responses is performed by modelling through a spline shape function the evolution of the relative acceleration along the height of the building. The coefficients of the spline function are determined by interpolating available responses in terms of absolute accelerations taking into account boundary conditions. The optimal location for a given number of recording sensors is defined as the one corresponding to the minimum value of the global error evaluated on the whole set of reconstructed responses. The criterion has been verified by using simulated responses of numerical models of multistorey frames and responses recorded on real buildings during the Northridge earthquake. A physical characterization of the location of available sensors leading to the minimum global error between calculated and real responses is proposed in terms of effective modal participation factors relevant to the principal modes of the structure. This characterization allows for frames of known modal characteristics the definition of a criterion for the choice of the location of a limited number of sensors for monitoring or vibration control purposes. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
38.
An algorithm to calculate direct velocity feedback gain with limited number of sensors is developed in a simple way such that a certain performance index is minimized according to QN control method. If a limited number of velocity outputs can be measured, full velocity responses of the whole structure can be interpolated based on the mode shapes. By defining the performance index function as a combination of the structure's velocity responses and control forces only, feedback gain can be determined according to QN control method with the external excitation being taken into account throughout the entire algorithm. Control forces are then regulated by the time‐invariant feedback gain matrix. The effective location of the active control devices for a building structure subjected to intermediate‐storey excitation has been determined to be in the three floors adjacent to the vibration source. Hence for the purpose of this paper, only the optimal placement of sensors is verified. It is shown in this paper that if the dynamic behaviour of the structure is well described by a mathematical model, sufficient response reduction effect can be achieved according to the new DVFC algorithm, and the degradation of control performance due to time delay can also be verified. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
39.
在水平分量的炮集记录中,数字三分量检波器直达波的椭圆率明显呈现出线性偏振的形态,并具有较高的分辨率,而模拟三分量检波器直达波的线性偏振不清晰,抗干扰能力差.在频谱分析和能量曲线分析的对比中,数字检波器的性能也高于模拟检波器.在PP波弱波阻抗界面的沙河组沙三12段,PS波表现出强反射界面,而且构造幅度比PP波剖面明显.在PS波剖面上,剖面深处两边的构造联系清晰可见,而在PP波剖面上很难解释剖面两边构造之间的关系,表明PS波资料对深层界面的成像能力有时不比PP波能力差,多分量资料在构造勘探上具有互补性.在沙四层底钻遇气层的马62井和马11井的测线CDP位置上,PP波和PS波的振幅比剖面上表现出低振幅比异常区,与钻井结果吻合.用多分量衰减系数或衰减比剖面,能够识别砂岩含气/水产生所产生的高频衰减异常.多分量地震属性及其比值剖面是储层含气异常指示的有效参数. 相似文献
40.