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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： S.A.P. Haddad J.M.H. Karel R.L.M. Peeters R.L. Westra W.A. Serdijn Electronics Research Laboratory Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technnology Delft Netherlands Department of Mathematics University of Maastricht Maastricht Netherlands

This paper presents an analog implementation of the complex wavelet transform using both the complex first order system (CFOS) and the Pade approximation. The complex wavelet filter design is based on the combination of the real and the imaginary state-space descriptions that implement the respective transfer functions. In other words, a complex filter is implemented by an ordinary state-space structure for the real part and an extra C matrix for the imaginary part. Several complex wavelets, such as Gabor, Gaussian and Morlet complex wavelets, are obtained and simulations demonstrate excellent approximations to the ideal wavelets.

关键词： Wavelet transforms Filters Mathematics Transfer functions Signal analysis Laboratories computer science Signal detection Wavelet analysis Information analysis

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ZnO Nanobelt Based Conductometric H2 and NO2 Gas Sensors

ZnO Nanobelt Based Conductometric H2 and NO2 Gas Sensors

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IEEE SENSORS

作者： A.Z. Sadek W. Wlodarski K. Kalantar-zadeh S. Choopun Sensor Technology Laboratory School of Electrical & Computer Engineering RMIT University Melbourne Australia Department of Physics Faculty of Science Chiang Mai University Chiang Mai Thailand

Conductometric H 2 and NO 2 gas sensors based on single-crystalline ZnO nanobelt sensitive layers have been developed. These layers were deposited using a rf magnetron sputterer. TEM and SEM characterization methods were employed to study the morphology of the nanobelts. These sensors were exposed to H 2 and NO 2 gases at operating temperatures between 225degC and 420degC. Study showed that sensors responded with highest magnitude at above 300degC. The fastest response and recovery times, with greater repeatability occurred at 385degC and 350degC for H 2 and NO 2 gases, respectively. Sensor with ZnO nanobelts has a much lower optimum operational temperature than that of conductometric sensors with other forms of ZnO crystal layers

关键词： Zinc oxide Hydrogen Gas detectors Temperature sensors Nanostructured materials Surface morphology Sensor phenomena and characterization Conducting materials Nanowires Gases

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Small UWB antenna with improved efficiency for pulse radiation

Small UWB antenna with improved efficiency for pulse radiati...

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International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials, iWAT

作者： A.A. Lestari A.B. Suksmono E. Bharata A.G. Yarovoy L.P. Ligthart International Research Centre for Telecommunications and Ra&r (IRCTR) Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technnology Delft Netherlands Department of Electrical Engineering Bandung Institute of Technology Microwave and Radio Telecommunication Laboratory Bandung Indonesia

The paper describes an ultra-wideband (UWB) antenna developed for impulse ground penetrating radar (GPR) applications. The antenna is a modified bow-tie antenna designed for short-range GPR applications such as road inspection and non-destructive testing of concrete. For these applications, the transmitted pulses should have minimal ringing to avoid masking of targets. This can be achieved by the application of resistive loading at the expense of radiation efficiency. We have attempted to improve a conventional bow-tie antenna usually used in GPR by reducing the antenna size and minimizing ringing, while at the same time improving the antenna radiation efficiency.

关键词： Ultra wideband antennas Loaded antennas Ground penetrating radar Microwave technology Directive antennas Antenna feeds Wire Dielectric substrates Laboratories Radar antennas

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Influence of frequency compensation on the linearity of negative feedback amplifiers

Influence of frequency compensation on the linearity of nega...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： K. van Hartingsveldt C.J.M. Verhoeven J. Willms Faculty of Electrical Engineering Mathematics and Computer Science Electronics Research Laboratory Delft University of Technnology Delft Netherlands National Semiconductor B. V. Hertogenbosch Netherlands

The paper discussed the impact of frequency compensation on the linearity of 2/sup nd/ and 3/sup rd/ order negative feedback amplifiers from a synthesis point of view. For each compensation method, simple expressions are derived that relate the amount of bandwidth required to get a desired linearity performance up to the end of the information band. The phantom zero technique is concluded to be by far the best compensation method as far as linearity is concerned.

关键词： Linearity Negative feedback Bandwidth Attenuation Negative feedback loops Poles and zeros Writing Frequency synthesizers Signal synthesis Imaging phantoms

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Receiver performance for an enhanced DGPS data channel

Receiver performance for an enhanced DGPS data channel

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18th International Technical Meeting of the Satellite Division of The Institute of Navigation, ION GNSS 2005

作者： Johnson, Gregory Kuhn, Michael Swaszek, Peter F. Hartnett, Richard Enge, Per Alion Science and Technology JJMA Marine Sector University of Rhode Island U.S. Coast Guard Academy Stanford University CT Office New London Institute of Navigation International Loran Association Armed Forces Communications Electronics Association Coast Guard Reserves Electrical and Computer Engineering University of Rhode Island USCGA's Faculty Aeronautics and Astronautics Stanford University School of Engineering GPS Research Laboratory ION IEEE

The Coast Guard currently operates a maritime differential GPS service consisting of two control centers and over 85 remote broadcast sites. This service broadcasts GPS correction information on marine radiobeacon frequencies to improve the accuracy and integrity of GPS. The existing system provides differential corrections over a medium frequency carrier using minimum shift keying (MSK) as the modulation method. MSK is a version of the Continuous Phase Frequency Shift Keying (CPFSK) modulation technique that is "spectrally compact," meaning that it is a narrow band modulation scheme. In a binary signaling channel, the two instantaneous frequencies for this modulation method are chosen in such a way so as to produce orthogonal signaling with a minimum modulation index. Current DGPS corrections are transmitted at a relatively low data rate, with message structures designed in an era when Selective Availability was in full operation. Greater demands for accuracy coupled with current operations in a "post SA" environment have prompted a reexamination of the DGPS data and signal structure, with an eye towards improving information rate while minimizing legacy user impact. A two-phased plan for a new generation of DGPS capability can be envisioned. In the first phase (near-term) new ionospheric messages would be introduced to allow greater DGPS accuracy at larger distances from the beacons. This capability could support both double (LI/L2) and triple (L1/L2/L5) frequency operation. This phase requires only the definition of the new message type(s) and the commitment of receiver manufacturers to implement the usage of the new data. In the second phase (intermediate future) a new signal would come on line to support RTK using two and three frequencies and homeland security messaging. This signal would have the capacity to send 500 bps or so without disrupting the legacy signal or legacy receiver performance. This new signal could be one of the new modulation techniques tha

关键词： Communication channels (information theory)

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Advanced DSP based system for image transmission over GSM/GPRS networks

Advanced DSP based system for image transmission over GSM/GP...

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12th International Workshop on Systems, Signals and Image Processing

作者： Mohorko, J Gleich, D Planinsic, P Ultra Advanced Research Center Ultra D.o.o. Co. Cesta Otona Zupancica 23a Slovenia Faculty of Electrical Engineering and Computer Science University of Maribor 2000 Maribor Gosposvetska ulica 84 Slovenia University of Maribor Slovenia Ultra D.o.o Co. Slovenia IEEE Slovenia Laboratory for Signal Processing and Remote Control University of Maribor Slovenia DLR Institute in Oberpfaffenhofen Germany SPIE

ISBN: (纸本)0907776205

In this article the development of the prototype of complex hierarchical organized sensor/control system that enables the capture and transmission of high quality images through mobile networks is described. Compression methods (codecs) for image information contents are used for effective image transfer through bandwidth limited communication channel. JPEG method is one of the implemented methods. It is the most known standard method on the field of lossy methods, but it gives poor results at high compression rations. The best compression methods are based on Wavelet transformation. In our implementation lifting scheme for a 9/7-filter bank was used to compute wavelet transform and the novel coding process and ordering of bit plane bits is presented which is comparable with a JPEG2000 codec in rate-distortion sense and has lower computational complexity as JPEG2000. A trade-off between a complexity and efficiency has been made to meet the cannel capacity of the GSM/GPPS network. Coder prototype is realized in compact DSP video module with relatively low cornputational power. Usability of the described methods is demonstrated on Internet based application 'Information system for image data collecting and distribution.

关键词： image compression wavelet transform coding internet protocol JPEG GSM GPRS DSP

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Illustrative visualization

Illustrative visualization

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VIS 05: IEEE Visualization 2005, Proceedings

作者： Viola, Ivan Gröller, Meister E. Hadwiger, Markus Bühler, Katja Preim, Bernhard Sousa, Mario Costa Ebert, David S. Stredney, Don Kanitsar, Armin Bruckner, Stefan Grimm, Sören Svakhine, Nikolai A. Jang, Yun Gaithert, Kelly Tietjen, Christian Krüger, Arno Peitgen, Heinz-Otto Isenberg, Tobias Hintze, Jana Hertel, Ilka Strauß, Gero Institute of Computer Graphics and Algorithms Vienna University of Technology Austria VRVis Research Center Vienna Austria Department of Simulation and Graphics University of Magdeburg Germany Department of Computer Science University of Calgary Canada School of Electrical and Computer Engineering Purdue University United States Ohio Supercomputer Center United States Institute of Computer Graphics and Algorithms Vienna University of Technology Austria VRVis Research Center Vienna Austria Electrical and Computer Engineering Purdue University United States IEEE Austria Department of Computer Science University of Calgary Canada Department of Computer Science Computer Graphics Research Lab. University of Calgary Canada Purdue University United States Ohio Supercomputer Center United States University of Texas Austin United States Interface Laboratory United States Biomedical Applications United States Department of Simulation and Graphics Otto-von-Guericke-University of Magdeburg Germany Otto-von-Guericke-University of Magdeburg FIN/ISG Germany Institute for Simulation and Graphics Department for Computer Science Otto-von-Guericke-University of Magdeburg Universitaetsplatz 2 39106 Magdeburg Germany Center for Medical Diagnosic Systems and Visualization Universitaetsallee 29 28359 Bremen Germany Department of Simulation and Graphics Otto-von-Guericke University of Magdeburg Germany ENT Department University Hospital of Leipzig Germany

ISBN: (纸本)0780394623

The tutorial presents state-of-the-art visualization techniques inspired by traditional technical and medical illustrations. Such techniques exploit the perception of the human visual system and provide effective visual abstractions to make the visualization clearly understandable. Visual emphasis and abstraction has been used for expressive presentation from prehistoric paintings to nowadays scientific and medical illustrations. Many of the expressive techniques used in art are adopted in computer graphics, and are denoted as illustrative or non-photorealistic rendering. Different stroke techniques, or brush properties express a particular level of abstraction. Feature emphasis or feature suppression is achieved by combining different abstraction levels in illustrative rendering. Challenges in visualization research are very large data visualization as well as multi-dimensional data visualization. To effectively convey the most important visual information there is a significant need for visual abstraction. For less relevant information the dedicated image space is reduced to enhance more prominent features. The discussed techniques in the context of scientific visualization are based on iso-surfaces and volume rendering. Apart from visual abstraction, i.e., illustrative representation, the visibility of prominent features can be achieved by illustrative visualization techniques such as cut-away views or ghosted views. The structures that occlude the most prominent information are suppressed in order to clearly see more interesting parts. A different smart way to provide information on the data is using exploded views or other types of deformation. Furthermore intuitive feature classification via 3D painting and manipulation with the classified data including label placement is presented. Discussed non-photorealistic and illustrative techniques from visualization and graphics are shown from the perspective as tools for illustrators from medicine, botany, archeology

关键词： Visualization

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Components for focused integrated pMUTs for high-resolution medical imaging

Components for focused integrated pMUTs for high-resolution ...

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IEEE Symposium (IUS) Ultrasonics

作者： A. Fleischman C. Chandrana Jin Fan J. Talman S. Garverick G. Lockwood S. Roy Department of Biomedical Engineering Cleveland Clinic Foundation Cleveland OH USA Department of Chemical and Biomedical Engineering Cleveland State University Cleveland OH USA Department of Electrical Engineering and Computer Science Case Western Reserve University Cleveland OH USA Naval Research Laboratory SFA Inc.orporated Washington D.C. USA Department of Physics Queen's University Belfast Kingston ONT Canada

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Transport of Mars-Crossing Asteroids from the Quasi-Hilda Region

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Physical Review Letters 2005年第23期94卷 231102-231102页

作者： Michael Dellnitz Oliver Junge Martin W. Lo Jerrold E. Marsden Kathrin Padberg Robert Preis Shane D. Ross Bianca Thiere Faculty of Computer Science Electrical Engineering and Mathematics University of Paderborn D-33095 Paderborn Germany Navigation and Mission Design Jet Propulsion Laboratory California Institute of Technology M/S 301-140L 4800 Oak Grove Drive Pasadena California 91109 USA Control and Dynamical Systems California Institute of Technology MC 107-81 Pasadena California 91125 USA Department of Aerospace and Mechanical Engineering University of Southern California Los Angeles California 90089 USA

We employ set oriented methods in combination with graph partitioning algorithms to identify key dynamical regions in the Sun-Jupiter-particle three-body system. Transport rates from a region near the 3∶2 Hilda resonance into the realm of orbits crossing Mars’ orbit are computed. In contrast to common numerical approaches, our technique does not depend on single long term simulations of the underlying model. Thus, our statistical results are particularly reliable since they are not affected by a dynamical behavior which is almost nonergodic (i.e., dominated by strongly almost invariant sets).

关键词： Astrophysics

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Relative output factor measurements of a 5 mm diameter radiosurgical photon beam using polymer gel dosimetry

Relative output factor measurements of a 5 mm diameter radio...

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作者： Pappas, E. Petrokokkinos, L. Angelopoulos, A. Maris, T.G. Kozicki, M. Dalezios, I. Kouloulias, V. Nuclear and Particle Physics Section Physics Department University of Athens Ilisia 157 71 Athens Greece Medical Physics Department MRI Unit University Hospital of Heraklion 711 10 Stavrakia-Heraklion Crete Greece Faculty of Textile Engineering Technical University of Lodz Zeromskiego St 116 90-543 Lodz Poland Institute of Applied Radiation Chemistry Technical University of Lodz Wroblewskiego Street 15 93-590 Lodz Poland Department of Biomedical Engineering University General Hospital Attikon 1 Rimini Street 124 62 Chaidari Athens Greece Department of Electrical Engineering and Computer Science National Technical University of Athens 9 Hroon Polytechniou Street 157 73 Athens Greece Medical Physics Department Anticancer-Oncologic Hospital of Athens Saint Savvas 171 Alexandras Ave. 115 22 Athens Greece Faculty of Medicine University Hospital of Heraklion University of Crete 711 10 Stavrakia-Heraklion Crete Greece

Besides the fine spatial resolution inherent in polymer gel-magnetic resonance imaging (MRI) dosimetry, the method also features the potential for multiple measurements of varying sensitive volume in a single experiment by integrating results in MRI voxels of finite dimensions (i.e., in plane resolution by slice thickness). This work exploits this feature of polymer gel dosimetry to propose an experimental technique for relative output factor (OF) measurements of small radiosurgical beams. Two gel vials were irradiated with a 5 and 30 mm diameter 6 MV radiosurgery beam and MR scanned with the same slice thickness and three different in plane resolutions. Using this experimental data set, 5 mm OF measurements with the PinPoint ion chamber are simulated by integrating results over a sensitive volume equal to that of the chamber. Results are found in agreement within experimental uncertainties with actual PinPoint measurements verifying the validity of the proposed experimental procedure. The polymer gel data set is subsequently utilized for OF measurements of the 5 mm beam with varying sensitive volume to discuss the magnitude of detector volume averaging effects. Seeking to correct for volume averaging, results are extrapolated to zero sensitive volume yielding a 5 mm OF measurement of (0.665%). This result compares reasonably with corresponding ionometric and radiographic film measurements of this work and corresponding, limited, data in the literature. Overall, results suggest that polymer gel dosimetry coupled with the proposed experimental procedure helps overcome not only tissue-equivalence and beam perturbation implications but also volume averaging and positioning uncertainties which constitute the main drawback in small radiosurgical beam dosimetry. © 2005 American Association of Physicists in Medicine.

关键词： Dosimetry

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