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AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference

作者： Kodys, A.D. Murray, R. Cassady, L. Choueiri, E.Y. Electric Propulsion and Plasma Dynamics Laboratory Mechanical and Aerospace Engineering Department Princeton University Princeton NJ 08511 United States NASA Graduate Student Research Program Princeton Plasma Science and Technology Program United States EPPDyL United States Applied Physics Group United States AIAA United States

ISBN: (纸本)1563478188

The inverted-pendulum method of thrust measurement for high-power electric thrusters is described analytically and experimentally. Two sources of uncertainty in the thrust measurements are investigated: those due to changes in the sensitivity of the inverted pendulum and those due to tare forces resulting from thermal stresses and electromagnetic forces acting on the flexural elements. An idealized analytical model shows that changes in sensitivity occur due to changes in the mass loading of the inverted pendulum and the temperature of the flexure elements. The sensitivity can be increased only at the expense of more stringent requirements on mass loading and thermal control. The results of the model are validated with measurements made using a carefully calibrated inverted pendulum thrust stand having several advantageous design features including gallium pots for current conduction, an optical two-axis displacement sensor, and careful consideration of flexure shape and cooling requirements. The sensitivity is shown to be constant over a wide range of operating conditions. Measurements show that thermal drifts of the stand are linear on the time scale of the thrust measurements and are less than 0.6% of the expected thrust. The thrust stand operation was demonstrated during experiments with a 30-kW lithium-fed applied-field magnetoplasmadynamic thruster. Under nominal conditions (400 A, 0.1 T, 17.5 mg/s) the thermal and electromagnetic tare forces were measured at less than 9% of the thrust and the total thrust uncertainty at ≤ 10% of the thrust.

关键词： Electric propulsion

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Aspect ratio effect in a thermally-driven rectangular open cavity with an isothermal shrouding wall

Aspect ratio effect in a thermally-driven rectangular open c...

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2006 ASME International mechanical engineering Congress and Exposition, IMECE2006

作者： Franco, Admilson Teixeira Ganzarolli, Marcelo M. Federal Technological University of Paraná Post-graduate Program in Mechanical and Materials Engineering Av. Sete de Setembro 3165 Curitiba Paraná 80230-901 Brazil State University of Campinas Energy Department Campinas São Paulo 13081-970 Brazil

ISBN: (纸本)0791837904

Natural convection in a rectangular open cavity with the presence of an isothermal shrouding wall is investigated. The horizontal walls of the cavity are adiabatic. One vertical wall is heated uniformly and another is open to a fluid reservoir. The isothermal shrouding wall is placed in front of this opening forming a vertical channel. Laminar and two-dimensional flow is assumed for a Rayleigh number ranging from 103 - 106. The numerical solution is carried out with the Finite Volume-SOLA method. The cavity aspect ratios considered are B = L/H = 0.5, 3.0 e 6.0, where L and H are the cavity width and cavity height, respectively. The distance b/H between the isothermal shrouding wall and the cavity opening is considered as 0.5 and 0.2. The effects of the Rayleigh number Ra, the cavity aspect ratios B and the ratio b/H, on the streamlines, isotherms and average Nusselt number are reported. Copyright © 2006 by ASME.

关键词： Heat sinks

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Numerical simulation of a thermally- driven open cavity with a shrouding wall

Numerical simulation of a thermally- driven open cavity with...

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2006 ASME International mechanical engineering Congress and Exposition, IMECE2006

ISBN: (纸本)0791837904

Natural convection in a square open cavity with and without the presence of a shrouding wall is analyzed. One vertical wall is heated and the horizontal walls are adiabatic. The other vertical wall is open to the ambient or a fluid reservoir. A shrouding wall is placed in front of this open wall forming a vertical open channel. Laminar and two-dimensional flow is assumed for the Rayleigh number ranging from 103 to 107 and the problem is solved numerically by using the Finite Volume-SOLA method. The average Nusselt number is reported for different values of the Rayleigh number and the distance of the shrouding wall to the open cavity. Copyright © 2006 by ASME.

关键词： Natural convection

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A weekend STEM enrichment program for tribal high school teachers and students

A weekend STEM enrichment program for tribal high school tea...

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113th Annual ASEE Conference and Exposition, 2006

作者： Padmanabhan, G. Lin, Wei Pieri, Robert Patterson, Floyd Khan, Eakalak North Dakota State University United States Department of Civil Engineering North Dakota State University United States North Dakota Water Resources Research Institute United States ASEE American Society of Civil Engineers United States Department of Environmental Engineering North Dakota State University United States Interdisciplinary Environmental and Conservation Sciences Graduate Program United States NDSU United States Department of Mechanical Engineering North Dakota State University United States Department of Electrical Engineering North Dakota State University United States

Attracting high school students to college engineering programs has been recognized as a challenge by several engineering organizations. One of the reasons for the low percentage enrolment of high school graduates into engineering programs is that many math/science teachers and counselors lack understanding of engineering applications within the subjects they teach and prospects associated with engineering careers. The instruction at the school level is often criticized for not adequately emphasizing science and mathematics, especially connections with engineering applications. Many students have difficulty connecting math and science courses to common phenomena seen all around and to future careers. This problem is further aggravated on Indian reservations in North Dakota because of their isolated locations and distance from industries. The authors developed a weekend academic program, "Sunday Academy", carried out on four North Dakota Indian reservations, to stimulate Native American students' interest in science, technology, engineering, and mathematics (STEM), to attract to engineering programs, and to engage high school teachers and tribal college instructors in the process of developing engineering and applied science lesson plans. The academy consisted of a series of one-day academic sessions presented monthly to junior and senior high school students. The lesson plans for the sessions were developed collaboratively by a group of university and community college faculty and high school teachers. This project provided unique opportunities for engineering professors to work with high school students directly, to familiarize high school teachers and tribal college instructors with engineering concepts and approaches, and to be knowledgeable about and sensitive to Indian culture. To make it a successful program, the authors had to overcome various challenges, including selection of lesson topics and hands-on activities that are interesting and suitable for the st

关键词： engineering education

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Resolution of optical microscope redefined

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Biophotonics International 2006年第7期13卷 42-45页

作者： Ram, Sripad Ward, E. Sally Ober, Raimund J. Joint Biomedical Engineering Graduate Program University of Texas Arlington University of Texas Southwestern Medical Center Dallas Center for Immunology Southwestern Medical Center Department of Electrical Engineering University of Texas Dallas Center for Immunology

A resolution measure that overcomes the limitations of Rayleigh's criterion was proposed that predicted the resolution of an optical microscope was not limited and that it can be improved by increasing the number of detected photons. An interdisciplinary approach was used to obtain the new resolution measure in which tools of advanced statistical image processing address a classical problem in optical microscopy. Single-molecule imaging experiments have verified that distances between single molecules that are well below Rayleigh's criterion can be measured with an accuracy in accordance with that prediction. An analytical expression for the fundamental resolution measure (FREM) was obtained by assuming imaging conditions analogous to those of Rayleigh's criterion. The proposed resolution measure shows that certain single-molecule experiments can be performed that were once unfeasible with optical microscope.

关键词： Optical microscopy

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Simultaneous monitoring tumor vascular and tissue oxygen tension under hyperbaric oxygen exposure

Simultaneous monitoring tumor vascular and tissue oxygen ten...

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biomedical Topical Meeting, BIO 2006

作者： Xia, Mengna Liu, Hanli Ren, Ya Mason, Ralph Levine, Benjamin Biomedical Engineering Graduate Program University of Texas at Arlington Arlington TX 76013 United States Department of Radiology UT Southwestern Medical Center at Dallas Dallas TX United States Institute of Exercise and Environmental medicine UT Southwestern Medical Center at Dallas Dallas TX United States

We demonstrate the ability to simultaneously investigate breast tumor oxygen dynamics by Steady-state diffuse reflectance spectroscopy and FOXY oxygen sensor in response to hyperbaric oxygen intervention. © 2006 ...

ISBN: (纸本)1557528071

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An Implantable Multifunctional Needle Type Biosensor with Integrated RF Capability

An Implantable Multifunctional Needle Type Biosensor with In...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Nan-Fu Chiu Jmin-Min Wang Lung-Jieh Yang Cheng-Wei Liao Chun-Hao Chen Hsiao-Chin Chen Shey-Shi Lu Chii-Wann Lin National Taiwan University Taipei TW Department of Mechanical and Electro-Mechanical Engineering TamKang University Taipei Taiwan Institute of Biomedical Engineering National Taiwan University Taipei Taiwan Graduate Institute of Electronics Engineering National Taiwan University Taipei Taiwan

We report the development of an implantable multifunctional (glucose and cholesterol) needle type biosensor with integrated RF wireless circuitry for continuous in vivo monitoring of metabolites during short term stays in emergency room or intensive care unit. Silicon-based MEMS technologies are used for the fabrication of micro needle sensors. The whole device is covered by a biocompatible Parylene layer with opening structure at the active areas of electrodes. Electropolymerization of active biomolecules and conducting polymer provides in situ nanoscale physical entrapments of various oxidoreductases (glucose oxidase and cholesterol oxidase) and functions as a viable matrix for the construction of micro amperometric biosensors. Hybrid CMOS fabrication processes are used to accomplish the 433 MHz ASK RF transmitter and receiver (0.18 muM CMOS 1P6M process) and the data converter (0.35 mum CMOS 2P4M process). We will present and discuss the detail design and the integrated system performance in this paper

关键词： Needles Biosensors Radio frequency CMOS process Sugar Fabrication Wireless sensor networks Circuits In vivo Monitoring

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SiO2-coated porous anodic alumina membrane for electroosmotic pumping

SiO2-coated porous anodic alumina membrane for electroosmoti...

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2006 ASME International mechanical engineering Congress and Exposition, IMECE2006

作者： Vajandar, Saumitra K. Xu, Dongyan Li, Deyu Markov, Dmitry Wikswo, John Hofmeister, William Interdisciplinary Graduate Program in Materials Science Vanderbilt University Nashville TN 37235 United States Department of Mechanical Engineering Vanderbilt University Nashville TN 37235 United States Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 United States Center for Laser Applications University of Tennessee Space Institute Tullahoma TN 37388 United States

ISBN: (纸本)0791837904

Electroosmotic pumping has been extensively used in biomedical lab-on-a-chip devices and micropumps for critical applications such as microelectronic cooling. In many applications, a high flow rate is a key requirement in desired performance so constant efforts have been made to increase the pumping flow rate through unit area to achieve the compact design. We report here an attempt of using SiO2-coated anodic porous alumina membrane as the material to achieve high electroosmotic pumping flow rate. High quality porous alumina membranes of controllable pore diameter in the range of 20-300 nm and pore length of 60-100 μm have been fabricated with electrochemical anodization. The pores are uniform and hexagonally packed with a high porosity of up to 50% and a tortuosity of a bare minimum of unity. In addition, the inner surface of the pores could be conformally coated with a thin layer (∼ 5 nm) of SiO2 with sol-gel chemistry to achieve a high zeta potential. Scanning electron microscopy of the cross section of the membrane verified these facts. Electroosmotic pumping performance of these membranes has been investigated using standard relevant aqueous electrolyte buffer solutions and results showed that SiO2-coated porous alumina could achieve a higher flow rate compared with other microporous materials such as glass frit and porous silicon reported in the literature. Copyright © 2006 by ASME.

关键词： Membranes

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Statistical Evaluation of The Cleft Lip Nose Deformity Image

Statistical Evaluation of The Cleft Lip Nose Deformity Image

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： D. W. Kim J. T. Kim H. K. Hong K. C. Nam J. H. Park Department of Medical Engineering Yonsei University College of Medicine Seoul Korea Graduate Program in Biomedical Engineering Yonsei University Seoul Korea Siemens Ultrasound Group Korea Division R & D Planning Team Seongnam Korea

Cleft lip is a congenital deformity condition with separation of the two sides of the lip and causes nose deformity. Evaluation of surgical corrections and assessment of prognosis in nose deformity depend mainly on doctor's subjective judgment. Development of an objective assessment tool in evaluation of the cleft lip nose deformity patients will help in advancement and evaluation of surgical techniques. Therefore, our study aimed on quantitative assessment of a cleft lip nose deformity by comparing following parameters gathered from a photographic image of a cleft lip patient: (1) angle difference between two nostril axes, (2) center of the nostril and distance between two centers, (3) overlapped area of two nostrils and (4) the overlapped area ratio of two nostrils. Assessment results of the nose deformity were statistically analyzed with evaluation results from three highly experienced plastic surgeons. In addition, regression model was developed using correlation relationship and factor analysis of parameters from the results of image analysis

关键词： Birth disorders Nose Surgery Image analysis biomedical imaging Medical diagnostic imaging biomedical engineering Cities and towns USA Councils Educational institutions

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A Non-Rigid Image Registration Technique for 3D Ultrasound Carotid Images using a "Twisting and Bending" Model

A Non-Rigid Image Registration Technique for 3D Ultrasound C...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： N.D. Nanayakkara B. Chiu A. Samani J.D. Spence J. Samarabandu A. Fenster Imaging Research Laboratories Robarts Research Institute and Graduate Program in Biomedical Engineering University of Western Ontario London ONT Canada Department of Medical Biophysics and Graduate Program in Biomedical Engineering University of Western Ontario London ONT Canada Departments of Neurology and Clinical Pharmacology Robarts Research Institute University of Western Ontario and Stroke Prevention and Atherosclerosis Research Centre London ONT Canada Department of Electrical & Computer Engineering University of Western Ontario London ONT Canada

Atherosclerosis at the carotid bifurcation resulting in cerebral emboli is a major cause of ischemic stroke. Most strokes associated with carotid atherosclerosis can be prevented by lifestyle/dietary changes and pharmacological treatments if identified early by monitoring carotid plaque changes. Sensitive monitoring of plaque changes in volume and morphology requires that 3D ultrasound (US) images of carotid plaque obtained at different time points be registered and evaluated for change. This registration technique should be non-rigid, since different head positions in image acquisitions cause relative bending and torsion in the neck, producing non-linear deformations between the images. We modeled the movement of the neck using a "twisting and bending model" with only six parameters for non-rigid registration. We used a Mutual Information (MI) based image similarity measure with the Powell optimization method as they have been used effectively in US image registration applications. For evaluation of our algorithm, we acquired 3D US carotid images from three subjects at two different head positions to simulate images acquired at different times. Then, we registered each image set using our "twisting bending model" based non-rigid registration algorithm. We calculated the Mean Registration Error (MRE) between the segmented vessel surfaces in the target image and the registered image using a distance-based error metric. We repeated the experiment with only rigid registration to compare the capabilities of the proposed algorithm in improving registration of 3D carotid US images. The average registration error was 1.03plusmn0.23 mm using our non-rigid registration technique, while it was 1.50plusmn0.50 mm when we applied the rigid registration alone

关键词： Image registration Ultrasonic imaging Atherosclerosis Monitoring Head Neck Bifurcation Morphology Mutual information Optimization methods

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