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Electrothermal Defect Detection in Powder Metallurgy Compacts

AIP Conference Proceedings 2006年第1期820卷 1201-1208页

作者： Souheil Benzerrouk Reinhold Ludwig Diran Apelian 1Powder Metallurgy Research Center Metal Processing Institute Worcester Polytechnic Institute Worcester MA 01609 2Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA 01609

Faced with increasing market pressures, metal part manufacturers have turned to new processes and fabrication technologies. One of these processes is powder metallurgy (P/M), which is employed for low‐cost, high‐volume precision part manufacturing. Despite many advantages, the P/M process has created a number of challenges, including the need for high‐speed quality assessment and control, ideally for each compact. Consequently, sophisticated quality assurance is needed to rapidly detect flaws early in the manufacturing cycle and at minimal cost. In this paper we will discuss our progress made in designing and refining an active infrared (IR) detection system for P/M compacts. After discussing the theoretical background in terms of underlying equations and boundary conditions, analytical and numerical solutions are presented that are capable of predicting temperature responses for various defect sizes and orientations of a dynamic IR testing system. Preliminary measurements with controlled and industrial samples have shown that this active IR methodology can successfully be employed to test both green‐state and sintered P/M compacts. The developed system can overcome many limitations observed with a standard IR testing methodology such as emissivity, background calibration, and contact resistance.

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Acoustic Backscatter Features Associated with Production of Tissue Homogenate using Pulsed Cavitational Ultrasound Therapy

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AIP Conference Proceedings 2006年第1期829卷 323-327页

作者： Jessica E. Parsons Charles A. Cain J. Brian Fowlkes 1Department of Biomedical Engineering University of Michigan Ann Arbor MI 48109 2Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109 3Department of Radiology University of Michigan Ann Arbor MI 48109

The use of a spatial variability criterion for acoustic backscatter is investigated as a potential method to assess lesion morphology and size in pulsed cavitational ultrasound therapy (PCUT). Backscatter signals were recorded during varied acoustic exposures that produced lesions in which tissue homogenate was either present or absent. Spatial variability was quantified by tracking changes in cross‐correlation sequences of A‐lines received during each exposure. Distributions of mean spatial variability are observed to be significantly higher for mechanically homogenized lesions than for those in which no homogenate is observed. A threshold spatial variability criterion is defined based on these distributions and is shown to be highly correlated (> 95%) with damage morphology. Furthermore, backscatter associated with the formation of homogenized lesions is characteristically observed to migrate away from the transducer during insonation. The magnitude of this backscatter shift is related to the axial dimension of the resultant lesion.

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Development of the Non‐Destructive Evaluation System Using an Eddy Current Probe for Detection of Fatigue Damage in a Stainless Steel

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AIP Conference Proceedings 2006年第1期820卷 323-329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

The non‐destructive evaluation system which is developed using an eddy current probe to evaluate fatigue damage in an austenitic stainless steel is reported in this paper. This probe is composed of the ferrite core and two pick‐up coils connected differentially. The eddy current induced by the excitation coil is disarranged by nonuniform distribution of electromagnetic characteristics due to fatigue damage. The structural function of the eddy current probe proposed, enable to detect the eddy current disarrangement by fatigue damage. This probe detects the change of electromagnetic characteristics in the direction of X. In this paper, SUS304, a austenitic stainless steel was used as the sample. The experimental results show that the output voltage of the probe clearly depends on the number of stress cycles.

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Investigation and complexity analysis of a spatial audio codec based on a programmable media-processor

Investigation and complexity analysis of a spatial audio cod...

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IEEE International Conference on Consumer Electronics (ICCE)

作者： Chia-Hao Chang Jin-Hau Kuo Chi-Hao Wu Ja-Lin Wu The Communications and Multimedia Laboratory 'Graduated Institute of Networking and Multimedia National Taiwan University Taipei Taiwan The Communications and Multimedia Laboratory 2Department of Computer Science and Information Engineering National Taiwan University Taipei Taiwan

This paper presents a complexity analysis of a spatial audio coding scheme (known as MPEG surrounding) based on a commercially available programmable device. The analysis mainly focuses on the complexity of spatial audio cue analysis and synthesis, especially for the additional special tools used during the spatial cue synthesis stage. The analysis results can be a reference during building up a SAC codec on a DSP

关键词： Codecs Audio coding Multimedia systems Proposals High definition video Streaming media Motion pictures Digital audio players Multimedia communication Laboratories

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High Velocity Particle Cloud Generation by Pulse Laser Ablation of Ground Glass Surface

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AIP Conference Proceedings 2006年第1期830卷 268-271页

作者： Kunihito Nagayama Yuriko Kotuska Motonao Nakahara Shiro Kubota 1Department of Aeronautics and Astronautics Faculty of Engineering Kyushu University Fukuoka 812‐8581 Japan 2Department of Computer and Communication Faculty of Engineering Fukuoka Institute of Technology Fukuoka 811‐0295 Japan 3Research Center for Explosion Safety National Institute of Advanced Industrial Science and Technology AIST Tsukuba 305‐8569 Japan

Enhancement of laser energy absorption has been demonstrated by pulse laser ablation of solid target whose surface was intentionally roughened. We have studied pulse laser ablation of roughened surface of ground glass surface by focusing a laser pulse through transparent plate from rear side. Ablation process has been observed by high speed framing camera. Burst of small fragments of glass has been observed in the present experiment. By using ns‐duration Nd:YAG laser of around 100 mJ per pulse, observed peak velocity of glass particle cloud ranges 0.5 km/s to 1.5 km/s. SEM observation of the ground glass surface revealed that virgin glass surface is covered with plenty of micro cracks, while cleavage surface structure has been evidenced in the damaged surface area.

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A Study of Effects of Tissue Inhomogeneity on HIFU Beam

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AIP Conference Proceedings 2006年第1期829卷 201-205页

作者： Viren Amin Ron Roberts Tao Long R. B. Thompson Timothy Ryken 1Center for Nondestructive Evaluation Iowa State University Ames Iowa 2Department of Electrical and Computer Engineering Iowa State University Ames Iowa 3Department of Neurosurgery University of Iowa Iowa City Iowa 3aDepartment of Radiation Oncology University of Iowa Iowa City Iowa

The potential of high‐intensity focused ultrasound (HIFU) will not be realized unless the effects of overlaying tissues are understood in such a way that allows for estimation of HIFU dose distribution at a target tissue. We employ computational models to examine the impact of phase aberration on tissue ablation. Thompson and Roberts have recently studied the effects of phase aberration on ultrasound focusing in aerospace engine materials such as titanium alloy, and have developed a computational model to examine these effects. The ultrasound beam observed after transmission through the fused quartz (homogeneous) and that observed after transmission through the titanium (inhomogeneous) demonstrate the severe beam wavefield amplitude distortion introduced by the velocity inhomogeneity‐induced phase aberration. We study applicability of this approach to model phase aberration in inhomogeneous tissues and its effect on HIFU dose distribution around the focus. It is hypothesized that the ill‐effects of phase aberration accumulate during propagation through intervening tissue in which field intensities are substantially lower than that in the focal zone, and it is therefore appropriate to use a linear acoustic model to describe the transport of energy from the transducer to the volume targeted for ablation. We present initial results of the simulation and experiments of beam measurements under water without and with different tissue layers.

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HIFU Therapy Planning Using Pre‐treatment Imaging and Simulation

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AIP Conference Proceedings 2006年第1期829卷 206-210页

作者： Viren Amin Liangshou Wu Ron Roberts R. B. Thompson Timothy Ryken 1Center for Nondestructive Evaluation Iowa State University Ames Iowa 2Department of Electrical and Computer Engineering Iowa State University Ames Iowa 3Department of Neurosurgery University of Iowa Iowa City Iowa 3aDepartment of Radiation Oncology University of Iowa Iowa City Iowa

Current HIFU challenges include amount of tissue that can be destroyed by a single exposure, the inability to treat through bone, difficulty in monitoring therapy in real‐time, and difficulty in planning the strategy before therapy. Technological advances such as multi‐transducer or array beam generator, instrumentation and image‐based guidance of HIFU treatment promise to overcome many of these problems. However, there is limited work toward HIFU dosimetry and therapy planning. We present a systematic approach for developing pre‐treatment planning and HIFU dose calculations for specific target location using simulations and imaging data. We also present initial techniques and tools towards HIFU treatment planning (targeted for open‐skull brain tumor therapy) using patient‐specific pre‐therapy imaging (e.g., CT or MRI) similar to dosimetry and planning for radiation therapy. This work has potential to aid development of optimized high‐precision HIFU dosimetry and patient‐specific planning strategies for complex and sensitive applications such as in brain tumor HIFU therapy. If successful, it potentially could reduce the guess work on dosage parameters and thereby reducing the overall treatment duration and reduced exposure to non‐target tissues.

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Piezoelectric‐Crystal‐Resonator High‐Frequency Gravitational Wave Generation and Synchro‐Resonance Detection

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AIP Conference Proceedings 2006年第1期813卷 1280-1289页

作者： Robert M. L. Baker, Jr. R. Clive Woods Fangyu Li 1GRAVWAVE LLC 8123 Tuscany Avenue Playa del Rey CA 90293 2Department of Electrical and Computer Engineering 2128 Coover Hall Iowa State University Ames Iowa 50011‐3060 2aMicroelectronics Research Center 2128 Coover Hall Iowa State University Ames Iowa 50011‐3060 3Department of Physics Chongqing University Chongqing 400044 P.R. CHINA

Here we show the generation of high‐frequency‐gravitational‐waves (HFGWs) utilizing piezoelectric elements such as the ubiquitous Film‐Bulk‐Acoustic‐Resonators (FBARs), found in cell phones, as energized by inexpensive magnetrons, found in microwave ovens, generating GWs having a frequency of about 4.9GHz and their detection by means of new synchro‐resonance techniques developed in China. In the 1960s Weber suggested piezoelectric crystals for gravitational‐wave (GW) generation. Since then researchers have proposed specific designs. The major obstacle has been the cost of procuring, installing, and energizing a sufficient number of such resonators to generate sufficiently powerful GWs to allow for detection. Recent mass‐production techniques, spurred on by the production of cell phones, have driven the cost of resonators down. The new Chinese detector for detecting the 4.9×109Hz HFGW is a coupling‐system of fractal membranes‐beam‐splitters and a narrow, 6.1 cm‐radius, pulsed‐Gaussian‐laser or continuous‐Gaussian detection beam passing through a static 15T‐magnetic field. The detector is sensitive to GW amplitudes of ∼10−30 to be generated with signal‐to‐noise ratios greater than one. It is concluded that a cost‐effective HFGW generation and detection apparatus can now be fabricated and operated in the laboratory. If the two groups or clusters of magnetrons and FBARs were space borne and at lunar distance (e.g., at the Moon and at the lunar L3 libration point) and the quadrupole formalism approximately holds for GW radiators (the FBAR clusters) many GW wavelengths apart, then the HFGW power would be about 420 W and the flux about 2×105 Wm−2 (or more than one hundred times greater than the solar radiation flux at the Earth) focused at the focal spot, or remote‐HFGW‐emitter, anywhere in the Earth’s environs — on or below the Earth’s surface.

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A study of load allocation with equipment capability and dedication for wafer fab

A study of load allocation with equipment capability and ded...

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35th International Conference on computers and Industrial engineering, ICC and IE 2005

作者： Chen, J.C. Chen, C.W. Shiau, J.Y. Chiang, C.-S. Department of Industrial Engineering Chung-Yuan University Chung-Li Taiwan 2Department of Computer and Information Science Soochow University Taipei Taiwan

ISBN: (纸本)9755612653

Process specifications in wafer fabrication need precise definition. Moreover, concerns for quality are such that different steps requiring the same capabilities should be processed on the same equipment with these capabilities. This paper develops a Loading Allocation algorithm considering equipment Capability and Dedication (LACD) for wafer fab. Simulation results demonstrate that LACD obtains the best performance among the compared three loading allocation methods in terms of standard deviation of machine loading. This finding indicates that LACD can effectively balance the loading among different machines with the same capability on the planning horizon by taking into account the order's process requirements as well as the machine's capacity and capability.

关键词： Loading

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Nanoscale Characterization of Metal/Semiconductor Nanocontacts

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AIP Conference Proceedings 2005年第1期788卷 280-284页

作者： C. Tivarus K.‐B. Park M. K. Hudait S. A. Ringel J. P. Pelz 1Department of Physics The Ohio State University Columbus OH 2Department of Electrical and Computer Engineering The Ohio State University Columbus OH

Ballistic Electron Emission Microscopy (BEEM) and finite‐element electrostatic modeling were used to quantify how “small‐size” effects modify the energy barrier at metal/semiconductor nanostructure nanocontacts, formed by making Schottky contacts to cleaved edges of GaAs quantum wells (QWs). The Schottky barrier height over the QWs was found to systematically increase with decreasing QW width, by up to ∼140 meV for a 1nm QW. This is mostly due to a large quantum‐confinement increase (∼200 meV for a 1nm QW), modified by smaller decreases due to “environmental” electric field effects. Our modeling gives excellent quantitative agreement with measurements for a wide range of QW widths when both quantum confinement and environmental electric fields are considered.

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