检索结果-内蒙古大学图书馆

Ultrasonic imaging of defects in concrete pipelines

AIP Conference Proceedings 2002年第1期615卷 1254-1260页

作者： Michael Ciocco Jeremy Neyhart Shreekanth Mandayam Kauser Jahan Douglas B. Cleary 1Department of Electrical and Computer Engineering Rowan University Glassboro New Jersey 08028 2Department of Civil and Environmental Engineering Rowan University Glassboro New Jersey 08028

This paper describes the first stage of a research project to develop an automated vehicle for inspecting the structural integrity of concrete sewer pipelines. We have developed an innovative interrogation and signal processing algorithm for detecting and sizing defects in concrete media, irrespective of the composition of the concrete—a crucial factor for realizing an in-line inspection process for concrete pipes. We have simulated concrete pipeline inspection by fabricating concrete specimens of diverse compositions embedded with rectangular defects of varying depths immersed in synthetic wastewater of varying density. We present ultrasonic C-scans and their corresponding defect characterization profiles.

关键词：

来源：评论

学校读者我要写书评

暂无评论

A Fokker-Planck model for a two-body problem

引用

AIP Conference Proceedings 2002年第1期617卷 340-371页

作者： M. M. Bierbaum R. I. Joseph R. L. Fry J. B. Nelson 1The Johns Hopkins University/Applied Physics Laboratory Laurel Maryland 20723 2Department of Electrical and Computer Engineering The Johns Hopkins University Baltimore Maryland 21218

The evolution of the state-of-knowledge of system regarding the time-varying state of a particle in the two-body problem is deterministically treated in classical mechanics where no uncertainties in initial conditions or acting forces are assumed. When such uncertainties exist, a Fokker-Planck equation can be formulated that describes the propagation in time of the probability density of possible positions and velocities of a particle. Both dissipative and dispersive forces can be present. This approach allows one to infer the coordinates of a particle in phase space as a function of time (both past and future) subject to acknowledged uncertainties. The Fokker-Planck equation is derived from knowledge of both the deterministic equations of motion and the probability distributions of acting forces. In the absence of uncertainties in acting forces, there are three conserved quantities that correspond to energy, total angular momentum, and the component of angular momentum in the direction of the rotation of the larger body (taken as the earth). The solutions for several cases are discussed. In the first case, gravity is absent while dispersive forces are present. An exact solution of the Fokker-Planck equation is given for this case. In a second case, gravity is present while dispersive forces are not. Here, the solution is time-independent, i.e., a conserved quantity and hence can be normalized. In a third case, both gravity and dispersive effects are present. A solution is derived through a perturbation of the functional corresponding to the exponentiated system energy. The perturbation solution is about the first-order moments of the energy function and thus is a temporal perturbation of the maximum entropy equilibrium distribution.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Enhancing accuracy of data acquired by a laser vibrometer in a field setting

引用

AIP Conference Proceedings 2002年第1期615卷 2013-2019页

作者： E. S. Sazonov P. Klinkhachorn H. V. S. GangaRao U. B. Halabe 1Lane Department of Computer Science and Electrical Engineering West Virginia University Morgantown West Virginia 26506 2Department of Civil and Environmental Engineering Constructed Facilities Center West Virginia University Morgantown West Virginia 26506

The Laser Doppler Vibrometers (LDVs) have gained increased popularity among researchers and practitioners. However, LDVs suffer from their dependency on the optical properties of the surface and sensitivity to external interference that may be easily controlled in the laboratory environment. Applying an LDV to large structures in field setting poses new challenges. This paper considers the problems that were encountered during the design of an automated damage detection system for the Armored Vehicle Launched Bridge and solutions that were applied to enhance the accuracy of the acquired data.

关键词：

来源：评论

学校读者我要写书评

暂无评论

An automated damage detection system for armored vehicle launched bridge

引用

AIP Conference Proceedings 2002年第1期615卷 1326-1333页

This paper presents an overview of an automated damage detection system for the Armored Vehicle Launched Bridge (AVLB). The system utilizes a non-contact laser vibrometer mounted on a computer-controlled robotic gantry as the measurement sensor. Acquired data is automatically processed to obtain strain energy mode shapes, which are used as the damage indicator. The analysis of the strain energy mode shapes is performed by a fuzzy expert system. This system was successfully tested on a full-scale AVLB with different damage scenarios.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Evaluation of plane bending fatigue damage in metallic plates using the thin-film flux-gate magnetic sensor

引用

AIP Conference Proceedings 2002年第1期615卷 1553-1560页

作者： M. Oka T. Yakushiji Y. Tsuchida M. Enokizono 1Department of Computer and Control Engineering Oita National College of Technology 1666 Maki Oita 870-0152 Japan 2Department of Mechanical Engineering Oita National College of Technology 1666 Maki Oita 870-0152 Japan 3Faculty of Engineering Oita University 700 Dannoharu Oita 870-1192 Japan

To estimate the amount of fatigue damage in metallic plates such as steel and stainless steel, we have investigated the relationship between the amount of plane bending fatigue damage and residual magnetization. The magnetic flux density in the Z component (Bz) at 1 mm above a specimen caused by residual magnetization is measured by using a thin-film flux-gate magnetic sensor. From the results of our experiment, the magnetic flux density has clear dependence on the increase of bending stress and the number of stress cycles in austenitic stainless steel. The distribution of Bz on steel plates is changed by the amount of plane bending fatigue damage. But, the relationship between the change of Bz and the number of stress cycles is not clear in the case of steel plates. In this paper, the relationship between the amount of plane bending fatigue damage and residual magnetization in metallic plates is discussed.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Electron-phonon relaxation in hot-electron detectors below 1 K

引用

AIP Conference Proceedings 2002年第1期605卷 75-78页

作者： Boris S. Karasik Andrew V. Sergeev Michael E. Gershenson 1Jet Propulsion Laboratory California Institute of Technology Pasadena California 91109 2Department of Electrical and Computer Engineering Wayne State University Detroit Michigan 48202 3Department of Physics and Astronomy Rutgers University Piscataway New Jersey 08854

Recently proposed submillimeter hot-electron direct detectors rely on a weak thermal coupling between electrons and phonons. According to the theory, this should occur in impure films. So far, the experimental situation has been somewhat confusing. A number of works have shown a cubic temperature dependence of the electron-phonon relaxation rate below 1 K. In contrast to the traditional explanation, we show that it was not a clean limit behavior but rather an intermediate temperature asymptotics. In this case, an electron scattering from transversal phonons mediated by vibrating impurities/boundaries dominates. In our recent experiments we reached the dirty limit predicted by the theory in Hf and Ti films. A measured electron-phonon relaxation time followed the T−4 dependence and was a record-long (25 ms) at 40 mK.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Studies on the effects of pulsed-magnetic field treatment on magnetic materials

引用

AIP Conference Proceedings 2002年第1期615卷 1569-1576页

作者： M. J. Johnson L. C. Kerdus C. C. H. Lo J. E. Snyder J. Leib S. J. Lee M. Mina D. C. Jiles 1Center for NDE Iowa State University Ames Iowa 50011 2Department of Materials Science and Engineering Iowa State University Ames Iowa 50011 3Ames Laboratory USDoE Ames Iowa 50011 4Department of Electrical and Computer Engineering Iowa State University Ames Iowa 50011

We have carried out systematic studies to investigate the effects of pulsed-magnetic field treatment on the residual stresses of carbon steels, nickel and magnetic thin film samples. A test bed was constructed for complete control of the magnetic field profile. The magnetic properties and stress states of the samples were measured before and after the treatment. Results indicate that the magnetic treatment does not have any detectable effects on the stress state of the samples.

关键词：

来源：评论

学校读者我要写书评

暂无评论

MEMS loop heat pipe based on coherent porous silicon technology

引用

AIP Conference Proceedings 2002年第1期608卷 220-232页

作者： Debra Cytrynowicz Mohammed Hamdan Praveen Medis Ahmed Shuja H. Thurman Henderson Frank M. Gerner Eric Golliher 1Center for Microelectronic Sensors and MEMS Department of Electrical Computer Engineering and Computer Science University of Cincinnati Post Office Box 210030 Cincinnati Ohio 45221-0030 2Department of Mechanical Industrial and Nuclear Engineering University of Cincinnati Post Office Box 210030 Cincinnati Ohio 45221-0030 3Spacecraft Thermal Systems NASA John H. Glenn Research Center at Lewis Field 21000 Brookpark Road Mail-Stop 301-2 Cleveland Ohio 44135-3191

This paper discusses the theory, modeling, design, fabrication and preliminary test results of the MEMS loop heat pipe being developed at the Center for Microelectronic Sensors and MEMS at the University of Cincinnati. The emphasis is placed upon the silicon micro wick and its production through a novel technique known as Coherent Porous Silicon (CPS) Technology.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Control of microwave-propelled sails using delayed measurements

引用

AIP Conference Proceedings 2002年第1期608卷 452-456页

作者： E. Schamiloglu C. T. Abdallah D. Georgiev J. Benford G. Benford 1Department of Electrical and Computer Engineering University of New Mexico Albuquerque New Mexico 87131 2Department of Mechanical Engineering University of New Mexico Albuquerque New Mexico 87131 3Microwave Sciences Inc. 1041 Los Arabis Lane Lafayette California 94549 4Department of Physics and Astronomy University of California Irvine 4129 Frederick Reines Hall Irvine California 92697-4575

This paper is concerned with the control of carbon fiber sail structures that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) and at the University of California, Irvine. The passive dynamic stability in the one-dimensional (1-D) case was studied in an earlier paper in terms of the fixed points of the trajectories for the governing equations of motion. The simple 1-D model introduced the possibility of controlling a microwave-propelled sail using various nonlinear control strategies, using both position and velocity measurements. In the current paper, we assume that velocity measurements are unavailable, and that the position measurements are delayed (due to the finite speed of light). We then use a novel feedback that employs delayed position measurements only to stabilize the sail about an equilibrium position. The paper will also contain preliminary results on studying the stability of the full 3-D sail model, and potential control strategies.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Spatial Coherence of Currently Available EUV/Soft X‐Ray Sources

引用

AIP Conference Proceedings 2002年第1期641卷 607-612页

作者： Yanwei Liu David T. Attwood Jorge J. Rocca Henry C. Kapteyn Margaret M. Murnane 1Applied Science and Technology Graduate Group University of California Berkeley CA 94720 1aCenter for X‐Ray Optics Lawrence Berkeley National Lab Berkeley CA 94720 2Department of Electrical and Computer Engineering Colorado State University Fort Collins CO 80523 3Department of Physics University of Colorado Boulder CO 80309 3aJILA University of Colorado Boulder CO 80309 3bNIST Boulder CO 80309

Spatial coherence properties of 3 different kinds of coherent sources in extreme ultraviolet/soft x‐ray wavelength region, namely undulator, x‐ray laser and high harmonic generation source, are introduced. Advantage...

关键词：

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：