检索结果-内蒙古大学图书馆

smart structures and materials 1994 Conference - smart structures and Intelligent Systems

作者： WASHABAUGH, PD PETERS, KJ UNIV MICHIGAN ANN ARBORMI 48109

ISBN: (纸本)0819414859

Frequently in designing a structure to incorporate integrated sensors the stiffness of the system is sacrificed to improve sensitivity. By incorporating finite length measurement paths that tessellate throughout the volume of a structure, a measurement's sensitivity can be optimized while retaining structural rigidity. Thus the transducer element can be utilized as a critical load-bearing structure. Within the framework of linear elastostatics, the normal, transverse, and shear components of strain along a path can be integrated over a finite length to separate and yield external loading components. These measurements over a long distance accommodate the use of fiber- optic displacement sensors. The use of interferometric sensors in contrast with electrical strain gauges allows the precision and range of the component measurements to scale with the geometry of the device rather than the maximum strain in the structure. It becomes possible by virtue of these scaling properties to construct a stiff yet sensitive device. The design of stiff structures that measure all six resultant-load-components using both piezo-resistive and interferometric sensors is described. An advanced torsion sensor and a linear acceleration transducer are also discussed. In addition, invariant paths have been found that allow the in-situ integrity of a structural volume to be monitored with a single pair of displacement sensors. Finally, practical considerations in the design of finite length sensor path transducers are noted.

关键词： Sensors Transducers Fiber optics sensors Fiber optics Silicon 3D vision Interferometry Optical sensors Solids Structural design

来源：评论

学校读者我要写书评

暂无评论

GROUND-TESTING OF A MICROGRAVITY ISOLATION SYSTEM

GROUND-TESTING OF A MICROGRAVITY ISOLATION SYSTEM

引用

smart structures and materials 1994 Conference - smart structures and Intelligent Systems

作者： EDBERG, D VONFLOTOW, A CHA, P FISHER, B GANN, L ROE, A SOBERG, J MCDONNELL DOUGLAS AEROSP SYST PERFORMANCE & DYNAM ANALHUNTINGTON BEACHCA 92647

ISBN: (纸本)0819414859

This paper describes the results of current research being carried out at McDonnell Douglas Aerospace (MDA) to develop a flight-ready vibration isolation system for possible use on shuttle or space station. Measurements and predictions indicate that the natural vibration modes of these vehicles may be excited by on-board equipment and astronaut activities. These disturbances may be enough to upset the desired levels of microgravity. The MDA system consists of a very low frequency, flexible interface between a scientific payload and the orbiting host platform augmented by active acceleration feedback. The design of a system that will accommodate materials and biological experiments must take into account predicted input vibration levels, experiment services requirements, and logistic considerations. It must accommodate all these requirements while consuming the absolute minimum of the space available to the payload itself. The MDA isolator concept has been demonstrated in 3-axis testing in the laboratory and nearly meets the desired space station specifications. However, the design needs on-orbit testing to verify its performance in true space environment. This paper discusses some of the practical aspects of the design and operation of the system. NASA has notified MDA that a Phase A award for the development of a flight demonstration of our experiment will be made under its IN-Space Technology Experiment Program (IN-STEP).

关键词： Actuators Space operations Optical isolators control systems Electronics Vibration isolation Electrodes Aerospace engineering Data acquisition Signal attenuation

来源：评论

学校读者我要写书评

暂无评论

APPLICATION OF FUZZY LOGIC TO ACTIVE STRUCTURAL control 2

APPLICATION OF FUZZY LOGIC TO ACTIVE STRUCTURAL CONTROL

引用

2nd European Conference on smart structures and materials

作者： CASCIATI, F FARAVELLI, L YAO, T UNIV PAVIA DEPT STRUCT MECHI-27100 PAVIAITALY

ISBN: (纸本)0819417009

Severe environmental loads acting upon civil engineering structures can provide a significant hazard. Structural control, first formalized by Yao [10], is one tool that engineers today can use, especially in the retrofit of older existing structures that have been found to be deficient. Few active control strategies, however, can deal adequately with a lack of exact knowledge of system parameter values or nonlinear behavior. One strategy that appears to be effective is fuzzy logic control. Imprecise linguistic descriptions of system conditions (e.g., the velocity is slightly negative and the displacement is somewhat positive, so apply a small force in the negative direction) can be used as the basis for activating control forces through the mathematical rules created by Zadeh [11]. In this paper, we discuss some aspects of the application of fuzzy control to civil engineering problems and we present results from the control of linear, two-degree-of- freedom systems that are subjected to simulated seismic excitation.

关键词： Fuzzy logic control systems Civil engineering Actuators Sensors smart materials Complex systems Device simulation Earthquakes Mechanics

来源：评论

学校读者我要写书评

暂无评论

NEURAL-NETWORK-BASED SIGNAL MONITORING IN A smart STRUCTURAL SYSTEM

NEURAL-NETWORK-BASED SIGNAL MONITORING IN A SMART STRUCTURAL...

引用

Conference on smart Sensing, Processing, and Instrumentation

作者： CHEN, SS KIM, SK SUNY BUFFALO DEPT CIVIL ENGNBUFFALONY 14260

ISBN: (纸本)0819414867

This paper focuses on the signal processing aspect of a smart structure computational support environment for health monitoring, investigating the use of neural networks to identify and locate structural damage in a steel truss structure instrumented with accelerometers and strain gauges. Cracking damage is simulated by introducing sawcuts into the main members of the structure. Results using accelerometer data alone indicate that Quickprop backpropagation neural networks constitute a promising tool for these purposes, although network performance in locating damage should be improved by use of strain data as well.

关键词： Neural networks Signal processing Sensors Data acquisition Signal detection Diagnostics Structural health monitoring Data modeling Instrument modeling smart structures

来源：评论

学校读者我要写书评

暂无评论

GAUSSIAN-BEAM DISPLACEMENT SENSOR FOR MONITORING INTERSTORY DRIFT IN smart BUILDINGS

GAUSSIAN-BEAM DISPLACEMENT SENSOR FOR MONITORING INTERSTORY ...

引用

Conference on smart Sensing, Processing, and Instrumentation

作者： BENNETT, KD HOOVER, CW CHEN, RZ PLONE, MD LAFAYETTE COLL DEPT ELECT ENGNPHOTON TECHNOL LABEASTONPA 18042

ISBN: (纸本)0819414867

A method for measuring lateral displacements in structures is proposed based on the motion of a Gaussian optical beam. A sensor is designed and constructed using the free space output of a single mode optical fiber, which well approximates the Gaussian intensity distribution, and is tested in both quasi-static and dynamic displacement modes. Good agreement between the experimental data and the predicted output is obtained for small displacements of the size expected in real buildings. It is envisioned that this sensor could serve as the input to an active control system used to stabilize smart buildings experiencing earthquake and wind loads.

关键词： Sensors Buildings Gaussian beams Photodetectors Single mode fibers Calibration Earthquakes Optical fibers Free space Structural engineering

来源：评论

学校读者我要写书评

暂无评论

RESULTS ON A DYNAMIC MODEL OF PHASE TRANSITIONS IN SHAPE MEMORY ALLOYS WITH NON-CONVEX LANDAU-GINZBURG FREE ENERGY 2

RESULTS ON A DYNAMIC MODEL OF PHASE TRANSITIONS IN SHAPE MEM...

引用

2nd European Conference on smart structures and materials

作者： SPIES, RD UNIV NACL LITORAL CONICETINTECPEMARA-3000 SANTA FEARGENTINA

Abstract not available.

ISBN: (纸本)0819417009

Abstract not available.

关键词： Shape memory alloys Mathematical modeling Information operations smart materials Chemical elements Data modeling mathematics Partial differential equations Scientific research Iron

来源：评论

学校读者我要写书评

暂无评论

OPTIMAL-control OF INFINITE-ORDER smart COMPOSITE STRUCTURAL SYSTEMS USING DISTRIBUTED SENSORS

引用

COMPOSITES ENGINEERING 1994年第6期4卷 577-589页

作者： BUTLER, R RAO, V UNIV MISSOURI CTR INTELLIGENT SYSTROLLAMO 65401

In recent years there has been considerable interest in the design of spatially shaped distributed sensors for the control of infinite-order structural systems. The smart materials polyvinylidene fluoride (PVDF) and shape-memory alloys can be utilized in the development of customized distributed sensors. Sensor shape-optimization techniques are needed for the implementation of optimal control strategies. In this paper, a method for generating the shapes of distributed sensors using finite-dimensional approximations to desired curvature and curvature rate kernels is examined. The output of these spatially distributed sensors is utilized directly as the control signal for suppressing vibrations in infinite-order structural systems. This paper shows that the desired kernels can be generated directly from finite element models of distributed structures without generating displacement and displacement-rate kernels. The curvature and curvature-rate kernels are the desired kernels in the development of shape functions for PVDF sensors for the implementation Of controllers. This procedure requires covering the entire structure with a customized sensor for each kernel. To alleviate this problem, a sensor is proposed which covers a portion of the structure with spatially distributed material and uses an observer for the estimation of the states. The original control algorithm is implemented by using the proposed sensor and observer. The usefulness of a single, relatively small customized PVDF film sensor along with an observer to provide full state-feedback information for the entire structure is examined. The complexity and performance of the proposed control scheme are compared with the original distributed sensor implementation.

关键词：

来源：评论

学校读者我要写书评

暂无评论

smart structures and materials 1994: Passive Damping

Smart Structures and Materials 1994: Passive Damping

引用

smart structures and materials 1994: Passive Damping

The proceedings contain 30 papers. The topics discussed include: integrated active and passive control design methodology for the NASA LaRC CSI evolutionary model;actuator with built-in viscous damping for isolation and structural control;Adaptable passive viscous damper: an adaptable D-StrutTM;actuator with built-in viscous damping for isolation and structural control;bending vibration control of composite plate structures through intelligent constrained-layer treatments;and initial studies into the use of active constrained-layer damping for controlling resonant vibration.

关键词：

来源：评论

学校读者我要写书评

暂无评论

ENERGY EVALUATION ON BOUNDED NONLINEAR control LAWS FOR CIVIL ENGINEERING APPLICATIONS 2

ENERGY EVALUATION ON BOUNDED NONLINEAR CONTROL LAWS FOR CIVI...

引用

2nd European Conference on smart structures and materials

作者： GATTULLI, V UNIV ROMA LA SAPIENZA DIPARTIMENTO INGN STRUTTURALE & GEOTECNI-00185 ROMEITALY

ISBN: (纸本)0819417009

In the last decades researchers in the field of structural engineering have challenged the idea of facing natural hazard mitigation problems by adding to structures particular systems which are designed to protect buildings, bridges and other facilities from the damaging effects of destructive environmental actions. Among most protective systems and devices, active structural control, although having already reached the stage of full-implemented systems, still need theoretical investigation to achieve a complete exploitation of its capacity in reducing structural vibrations. In most of the operating systems (e.g. Soong and Reinhorn, 1993), linear control laws based on some quadratic performance function criteria are used since the design process for these linear strategies are fully developed and investigated. Moreover, the performances of structural systems controlled by linear techniques bring about some question concerning the complete and wise utilization of the capacity of control devices. Indeed, some of these inefficiencies are evident such as the inability to produce a significant peak response reduction in the first cycles of recorded or simulated time histories. (e.g. Reinhorn et al., 1993). Realizing that the expected maximum value for the required control force is a fundamental parameter in all processes to design the complete control system, in this paper it is shown that appropriate nonlinear control laws can significantly enhance the reduction of the system response under the same constraints imposed on the control force. Energy evaluation on the performance of different kinds of nonlinearities are reported such that a common base is built to perform comparative studies. These techniques have been successfully experimented on a structural model with ground excitations supplied by shaking table (e.g. Gattulli et al., 1994).

关键词： Nonlinear control control systems Complex systems Civil engineering control systems design Bridges Buildings Pollution control smart materials Structural engineering

来源：评论

学校读者我要写书评

暂无评论

FEEDBACK controlLERS FOR BROADBAND ACTIVE NOISE REDUCTION 2

FEEDBACK CONTROLLERS FOR BROADBAND ACTIVE NOISE REDUCTION

引用

2nd European Conference on smart structures and materials

作者： PETITJEAN, B LEGRAIN, I OFF NATL ETUD & RECH AEROSP F-92322 CHATILLONFRANCE

ISBN: (纸本)0819417009

The aim of the present paper is to demonstrate the efficiency of an LQG-based controller for the active control of the acoustic field radiated by a rectangular panel. This topic has been of interest for numerous researchers in the past 10 or 15 years, but very little attention has been paid to broadband disturbances occurring in a relatively high frequency range. These are unfortunately common features of noise perturbations in realistic structures such as airplanes or helicopters. The few articles that deal with this problem provide very scarce experimental results and are related to frequency bands where the structure dynamics is rather poor. From the outset, the problem at hand involves numerous difficulties, such as the modeling of the active structure itself and the possible large size of the controller. In the following, the experimental setup is described, then the controller design procedure is developed and finally some experimental results are shown that prove the efficiency of the method.

关键词： Acoustics Sensors Digital signal processing Actuators Denoising Feedback control Ferroelectric polymers Linear filtering Device simulation smart materials

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：