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2005 1st IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks, DySPAN 2005

作者： Brown, Timothy X. Interdisciplinary Telecommunication Program Electrical and Computer Engineering Department University of Colorado Boulder CO 80309-0530

ISBN: (纸本)1424400139

Recent FCC proceedings have considered the notion of unlicensed device operation in licensed bands. Licensed users are concerned about harmful interference while unlicensed device manufacturers are concerned that harmful interference is an imprecise design concept. This paper addresses three elements to this debate. First, it advocates for an explicit model of harmful interference to be included in unlicensed device rules. Such a model provides explicit bounded protection to the licensed user while providing assurances and performance goals to the unlicensed device manufacturers. Second, it assesses several proposed methods for unlicensed devices to avoid licensed users and develops variants of each that can achieve the necessary accuracy. Third, it presents an analytic model for assessing harmful interference that not only provides quantitative analysis, but, also provides insight into how factors such as directional antennas, power control, and licensed channel avoidance strategies affect the aggregate interference. Further, it suggests that complex factors such as unlicensed device modulation schemes can be captured in a simple measurement. These ideas are applied to the notice of proposed rulemaking on Unlicensed Operation in the TV Broadcast Bands. © 2005 IEEE.

关键词： Information services

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An analysis of unlicensed device operation in licensed broadcast service bands

An analysis of unlicensed device operation in licensed broad...

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IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks, DySPAN

作者： T.X. Brown Interdisciplinary Telecommunication Program Electrical and Computer Engineering Department University of Colorado Boulder CO USA

关键词： Interference TV broadcasting FCC Protection Investments Telecommunication computing Virtual manufacturing Directional antennas Power control Aggregates

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Transistor characteristics of thermal chemical vapor deposition carbon nanotubes field emission triode

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2005年第2期23卷 868-873页

作者： Y. M. Wong W. P. Kang J. L. Davidson W. Hofmeister S. Wei J. H. Huang Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 37235 Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville Tennessee 37235 Department of Materials Science and Engineering National Tsing Hua University Hsinchu 300 Taiwan Republic of China

A study of thermal chemical vapor deposition (CVD) grown carbon nanotubes (CNTs) field emitters in a triode amplifier configuration is reported. The CNT transistor characteristics were examined by integrating gate and anode with CNT cathode in two structural forms, utilizing a TEM grid (transmission electron microscope specimen holder) as the gate electrode and a micropatterned CNT with self-aligned gate. The TEM-grid CNT triode displayed clearly gate-controlled current modulation behavior with distinct cutoff, linear, and saturation regions, and a reasonable gate turn-on field of ∼5.4V∕μm despite a large cathode-gate spacing of ∼120μm . The field emission result established the basic transistor characteristics of CNTs in a triode configuration. A CNT triode construct with a self-aligned gated fabrication technique was also developed to realize a monolithic triode structure with shorter gate-cathode spacing, lowering gate voltage, and enhancing emission current. The triode exhibited a significantly lower gate turn-on voltage of ∼40V , and gate-controlled modulation of the emission current. An anode current density of ∼30mA∕cm2 was achieved at a gate voltage of ∼80V and an anode voltage of ∼200V . The dc characteristics for both of the CNT triodes were investigated, including Ia versus Va for different Vg . Moreover, dc parameters such as transconductance, amplification factors, and anode resistance of the triode amplifier were determined. The CNT triodes exhibited useful amplification factor and high output impedance.

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Effects of deposition and synthesis parameters on size, density, structure, and field emission properties of Pd-catalyzed carbon nanotubes synthesized by thermal chemical vapor deposition

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2005年第2期23卷 793-799页

作者： S. Wei W. P. Kang W. H. Hofmeister J. L. Davidson Y. M. Wong J. H. Huang Interdisciplinary Program in Materials Science Vanderbilt University Nashville Tennessee 37235 USA Department of Electrical and Computer Engineering Vanderbilt University Box 1661-B Vu Station B Nashville Tennessee 37235 USA Department of Chemical Engineering Vanderbilt University Nashville Tennessee 37235 USA Department of Materials Science and Engineering National Tsing Hua University Hsinchu 300 Taiwan Republic of China

The effects of deposition parameters and NH3 pretreatment on the size and distribution of Pd catalytic particles and subsequently their effects on the characteristics of the synthesized carbon nanotubes (CNTs) were systematically investigated. It was found that the size of Pd particles decreases and the particle density (total number of Pd particles per unit area) increases as the Pd film thickness decreases. Moreover, pretreatment of Pd film in NH3 gas promotes smaller Pd particles and higher particle density which is beneficial for CNT growth. The CNTs were synthesized by thermal chemical vapor deposition at 750 °C using methane (CH4) as the carbon source, and a mixture of Ar/H2 (80 vol %: 20 vol %) as a carrier gas with NH3 serving as a processing reagent. The incorporation of NH3 in CNT synthesis, per the specific pretreatment of catalytic film, has a distinct effect on the size and morphology of CNTs produced. The interrelation between processing, structure and emission behavior of CNTs produced with different synthesis conditions was examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and field emission measurements.

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Carbon nanotube growth from Cu–Co alloys for field emission applications

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2004年第3期22卷 1286-1289页

作者： W. Hofmeister W. P. Kang Y. M. Wong J. L. Davidson Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville Tennessee 37235 Interdisciplinary Graduate Program in Material Science and Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 37235 Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 37235

We have developed a method of catalyst preparation for carbon nanotube (CNT) growth that uses solid-state diffusion to precipitate Co particles in a Cu matrix and control the size and size distribution of catalyst particles. Copper is an excellent electrical and thermal conductor, and has a small or negligible solubility for Co. Cu–Co alloys of approximately 5 atm% Co were formed in bulk by splat quenching the liquid alloy and on Si substrates by e-beam evaporation of the alloy, sputtering of the alloy, and sputter deposition of thin films of pure Cu and Co. The Co easily precipitates from dilute solutions of Cu–Co with heat treatment. These alloys and films were used to generate uniform distributions of Co precipitates, and CNTs were successfully grown by plasma enhanced chemical vapor deposition (PE-CVD) and thermal CVD on the materials. These alloys can be patterned by photolithography and sputtering in order to grow CNTs in defined locations. Therefore, the technique is amenable to very large scale silicon integration for field emission applications. The results of this work and data from field emission studies are presented herein.

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A proposal for an integrated utilities engineering-Management M.S. program

A proposal for an integrated utilities Engineering-Managemen...

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2004 37th Annual Frontiers of Power Conference

作者： Barnes, Frank S. Fuchs, Ewald F. Tietjen, Jill S. Silverstein, Joann Ko, Hon-Yim Lookabaugh, Tom Brown, Timothy X. Sicker, Douglas C. University of Colorado AAAS IEEE International Engineering Consortium National Academy of Engineering Department of Electrical Engineering LLC McNeil Technologies Board for Girl Scouts Mile Hi Council Georgia Transmission Corporation of Tucker GA ABET Inc. National Council of Examiners for Engineering and Surveying SWE IEEE Power Engineering Society Department of Civil Environmental and Architectural Engineering UCB National Water Research Institute Women in Engineering Program Center of the American West College of Engineering Department of Civil Environmental and Archetectural Engineering University of Colorado Jet Propulsion Laboratory Computer Science Department Interdisciplinary Telecommunications Program University of Colorado Boulder University of Colorado Boulder Electrical Engineering and Interdisciplinary Telecommunications University of Colorado Boulder Department of Computer Science University of Colorado Boulder ITP Laboratory ACM Internet Society Faculty of the Progress and Freedom Foundation Institute for Regulatory Law and Economics Aspen Institute Communications and Society Program CU Computer and Communications Security Center Center for Science and Technology Policy Research Research and Engineering Center for Unmanned Vehicles Electrical and Computer Engineering Civil Environmental and Architectural Engineering

Electric, water, gas and transportation utilities face severe challenges associated with security, quality, availability, reliability and profitability issues. They must solve interrelated system problems with respect to generation of electricity, transportation of fuel, and potable as well as waste water. In the future, engineers and managers of utilities must be well versed in the different disciplines of engineering including electrical civil, mechanical and information technology. The University of Colorado at Boulder addresses this educational opportunity by proposing a novel Integrated Utilities Management program for M.S. candidates who have a solid B.S. background or equivalent in a related discipline. The M.S. program will consist of four interdisciplinary paths dealing with business management and legal topics as they relate to federal and state regulatory issues, as well as agency and people-related leadership issues. The electric utilities option of this program will be centered on three core courses related to electric power generation/transmission and distribution, security and availability, quality and reliability, economics and environmental policy, and utility finance;two elective courses from a group of courses that address nuclear power, waste water, solid waste, telecommunications, renewable energies, data communication, fuels and case studies;and one capstone course consisting of either operations research or the investigation and resolution of a pending utility project such as the right-of-way of transmission lines, specification of new power plants, retrofitting of power plants or their impact on the environment. It is expected that candidates for this MS program will come from universities, from utilities, and from private and public agencies. The MS program can be completed by full- or part time students within one or two years of intensive study, respectively. Courses will be taught both on campus and nationwide via the Center for Advanced

关键词： Public utilities

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The effects of process parameters on size, density, structure, and field emission properties of Pd-catalyzed carbon nanotubes synthesized by thermal chemical vapor deposition

The effects of process parameters on size, density, structur...

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International Conference on Vacuum Nanoelectronics (IVNC)

作者： S. Wei W.P. Kang W.H. Hofmeister J.L. Davidson Y.M. Wong J.H. Huang Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville TN USA Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN USA Department of Chemical Engineering Vanderbilt University Nashville TN USA Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan

In this study, various thicknesses of Pd catalytic films were deposited on Ti/Si substrates and pretreated with NH/sub 3/. The effects of catalyst deposition parameters and NH/sub 3/ pretreatment time (0, 1, and 10 minutes) on the size distribution of Pd catalytic particles, and subsequently, on the diameter and density of synthesized carbon nanotubes (CNTs) were investigated. The CNTs were synthesized by thermal CVD at 750/spl deg/C using methane (CH/sub 4/) as the carbon source, and a mixture of Ar/H/sub 2/ (80 vol.%/20 vol.%) as the carrier gas.

关键词： Carbon nanotubes Chemical vapor deposition Argon Hydrogen Scanning electron microscopy Morphology Substrates Materials science and technology Transmission electron microscopy Carbon dioxide

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Carbon nanotube growth from Cu-Co alloys for field emission applications

Carbon nanotube growth from Cu-Co alloys for field emission ...

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IEEE International Conference on Vacuum Microelectronics (IVMC)

作者： W. Hofmeister W.P. Kang Y.M. Wong J.L. Davidson Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville TN USA Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN USA

We have used Cu-Co alloy to generate uniform distribution of Co precipitates, and successfully grown CNTs by CVD on the Cu support.

关键词： Carbon nanotubes Conducting materials Transistors Application software Cobalt alloys Copper alloys Materials science and technology Hydrocarbons Chemical vapor deposition Nanocrystals

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On Classifying Daylight for Design

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International Journal of Architectural Computing 2003年第2期1卷 205-217页

作者： Daniel Glaser James Peng Interdisciplinary Doctoral Program University of California at Berkeley Computer Science Division 387 Soda Hall #1776 Berkeley CA 94720 - 1776 USA Department of Electrical Engineering and Computer Sciences University of California at Berkeley Computer Science Division 387 Soda Hall #1776 Berkeley CA 94720 - 1776 USA

In this paper, we present LiQuID, a tool for clustering lighting simulation data. Photographs are useful vehicles for both describing and making assessments of architectural lighting systems. A significant barrier to using photographs during the design process relates to the sheer volume of renderings that needs to be analyzed. Although there have been efforts to produce novel visualization systems to manage large sets of photographs, this research aims to reduce the complexity by classifying data into representative prototypes. A hypothetical case study is discussed.

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An approach to blind equalization of non-minimum phase systems

An approach to blind equalization of non-minimum phase syste...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： W.A. Sethares R.A. Kennedy Z. Gu Department of Electrical and Computer Engineering University of Wisconsin Madison WI USA Department of System Engineering RSPhysSE and Interdisciplinary Engineering Program Faculty of Science Australian National University Canberra ACT Australia

Blind equalization of systems which contain a nonminimum phase component is a difficult task. Minimizing the energy (l/sub 2/ minimization) of the equalizer output (under a fixed tap constraint) cannot be guaranteed to open the eye (to reliably unscramble the message) because it tends to converge to an equalizer setting that contains a reflection of the unstable zeros inside the unit circle. It is shown that, in at least one simple setup involving a mixture of minimum and nonminimum phase elements, an l/sub infinity / minimization of the equalizer output is the appropriate criterion which should be minimized in order to successfully open the eye. Utilizing a finite impulse response equalizer constrained to have a unity coefficient on the center tap, it is shown that for a large enough dimension (depending on the closeness of the zeros of the channel to the unit circle) the eye will be opened. There is no simple (gradient) scheme to exactly implement the l/sub infinity / minimization. The use of a gradient l/sub p/ scheme for large p is proposed.< >

关键词： Blind equalizers Finite impulse response filter Australia Council Information science Predistortion Distortion Cellular neural networks Quadrature amplitude modulation Stability

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