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NIST Authors in Bold

Displaying 36426 - 36450 of 74045

Contact mechanics and tip shape in afm-based nanomechanical measurements

August 31, 2005
Author(s)
Malgorzata Kopycinska-Mueller, Roy H. Geiss, Donna C. Hurley
Stiffness-load curves obtained in quantitative atomic force acoustic microscopy (AFAM) measurements depend on both the elastic properties of the sample and the geometry of the atomic force microscope (AFM) tip. The geometry of silicon AFM tips changes when

Growth Habits and Defects in ZnO Nanowires Grown on GaN/Sapphire Substrates

August 31, 2005
Author(s)
Igor Levin, Albert Davydov, Babak Nikoobakht, Norman A. Sanford, Pavel Mogilevsky
Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (0001) GaN/sapphire substrate using Vapor-Liquid-Solid (VLS) technique were studied using electron microscopy and X-ray diffraction. The results revealed presence of both

Growth habits and defects in ZnO nanowires grown on GaN/sapphire substrates

August 31, 2005
Author(s)
Igor Levin, Albert Davydov, Babak Nikoobakht, Norman Sanford, Pavel Mogilevsky
Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (00.1) GaN/sapphire substrate using the vapor-liquid-solid (VLS) technique were studied using electron microscopy and x-ray diffraction. The results revealed presence of both

Impedance Control for Critically Coupled Cavities

August 31, 2005
Author(s)
Billy F. Riddle, Craig Nelson
Cavity resonators are often used in low phase noise oscillators that utilize carrier suppression. These oscillators are employed in systems that measure phase noise in frequencies as hight at 100 GHz. In order to achieve the maximum suppression needed in

Protected Elevators and the Disabled

August 31, 2005
Author(s)
Richard W. Bukowski
The NIST investigation into the World Trade Center attacks has renewed interest in the deployment of protected elevators that can be used to facilitate the evacuation of occupants and access by first responders during fires and other emergencies in tall

Relative Permittivity and Loss Tangent Measurement Using the NIST 60 mm Cylindrical Cavity

August 31, 2005
Author(s)
Michael D. Janezic, Jolene D. Splett, Kevin J. Coakley, Raian K. Kaiser, John H. Grosvenor Jr
In order to develop a dielectric Standard Reference Material (SRM), a measurement system for measuring the relative permittivity and loss tangent of dielectric materials is presented. To achieve the necessary level of measurement accuracy, we selected the

RoboCup 2004: Rescue Robot League

August 31, 2005
Author(s)
Adam S. Jacoff, S Tadokoro
This article discusses the RoboCupRescue Robot League competition held this year in Lisbon, Portugal. These annual competitions increase awareness of the challenges involved in urban search and rescue (USAR) applications, provide objective evaluation of

A Comparison of GPS Common-View Time Transfer to All-in-View

August 29, 2005
Author(s)
Marc A. Weiss, G. Petit, Zhiheng Jiang
All-in-view time transfer is being considered to replace common-view for computing the links of International Atomic Time (TAI). Components in all-in-view GPS time transfer that do not cancel as they do in the common-view technique are the satellite clock

A New Microwave Synthesis Chain for the Primary Frequency Standard NIST-F1

August 29, 2005
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Elizabeth A. Donley, F Levi, Thomas E. Parker
We present the design and measurements of the microwave synthesis chain presently used in NIST-F1, the laser-cooled cesium fountain primary frequency standard in operation at NIST, Boulder, CO. This system has been used in two accuracy evaluations of NIST

Component-Level Demonstration of a Microfabricated Atomic Frequency Reference

August 29, 2005
Author(s)
Vladislav Gerginov, Svenja A. Knappe, P Schwindt, V Shah, Li-Anne Liew, John Moreland, Hugh Robinson, Leo W. Hollberg, John E. Kitching, Alan Brannon, J Breitbarth, Z Popovic
We demonstrate component-level functionality of the three critical subsystems for a chip-scale atomic clock: the physics package, the local oscillator and the control electronics. In addition, we demonstrate that these three components functioning together

Evaluation of Pressure Oscillator Losses

August 29, 2005
Author(s)
Peter E. Bradley, Michael A. Lewis, Ray Radebaugh
Efficiencies of regenerative cryocoolers are influenced by losses within the pressure oscillator (compressor). An evaluation of these losses is important when searching for ways to improve the overall cryocooler efficiency. Typically, compressor efficiency

GerberTranslator: Moving towards new PCB standards

August 29, 2005
Author(s)
Matthew L. Aronoff, John V. Messina
This paper describes the key features of the NIST-developed software tool called ?GerberTranslator?. GerberTranslator is a software translator which automates the majority of the work in converting a printed circuit board (PCB) described in the industry

Impedance Measurements of Inertance Tubes

August 29, 2005
Author(s)
Michael A. Lewis, Peter E. Bradley, Ray Radebaugh
The flow impedance of an inertance tube 5.74 mm inside diameter and 2.36 m long coupled to various reservoir volumes was measured and compared with that predicted by a model based on a transmission line analogy. Though data at other average pressures and

Laser cooling and launching performance in a (1,1,1) -geometry atomic fountain

August 29, 2005
Author(s)
Elizabeth A. Donley, Thomas P. Heavner, John O'Brien, Steven R. Jefferts, F Levi
We have successfully cooled and launched cesium atoms in the (1,1,1) atomic fountain geometry at temperatures as low as 0.8 mK. This corresponds to a mean thermal velocity of 0.7 cm/s, which is two times the photon recoil velocity of 0.35 cm/s. Factors

Noise Properties of Microwave Signals Synthesized with Femtosecond Lasers

August 29, 2005
Author(s)
Eugene N. Ivanov, John J. McFerran, Scott A. Diddams, Leo W. Hollberg
We discuss various aspects of high resolution phase noise measurements at microwave frequencies. This includes methods to achieve thermal noise limited sensitivity and improved immunity to amplitude fluctuations of microwave signals. A few prototype

On the Power Dependence of Extraneous Microwave Fields in Atomic Frequency Standards

August 29, 2005
Author(s)
Steven R. Jefferts, Jon H. Shirley, Neil Ashby, Thomas P. Heavner, Elizabeth A. Donley, F Levi
We show that the frequency bias caused by distributed cavity phase has a strong dependence on microwave power. We also show that frequency biases associated with microwave leakage have distinct signatures in their dependence on microwave power and the

Sources of Instabilities in Two-Way Time Transfer

August 29, 2005
Author(s)
Thomas E. Parker, Victor S. Zhang
Two-Way Satellite Time and Frequency Transfer (TWSTFT) has become an important component in the international system for comparing time and frequency over long distances. In order to make further improvements in the stability of TWSTFT a more complete

The Inter-American Metrology System (SIM) Common-View GPS Comparison Network

August 29, 2005
Author(s)
Michael A. Lombardi, Andrew N. Novick, Jose M. Lopez, Jean-Simon Boulanger, Raymond Pelletier
The Inter-American Metrology System (SIM) consists of national metrology institutes in 34 member nations located throughout North, Central, and South America. Currently, at least ten SIM laboratories pursue time and frequency metrology, and are responsible

W-band dual channel AM/PM noise measurement system - an update

August 29, 2005
Author(s)
Archita Hati, Craig Nelson, J Nava, David A. Howe, Fred L. Walls, Huascar Ascarrunz, Justin Lanfranchi, Bill Riddle
We discuss the performance of a W-band (92-96) GHz amplitude modulated (AM) and phase modulated (PM) noise measurement system. The system uses two nearly identical channels to measure the residual noise in amplifiers in pulsed mode with a duty cycle of 10%
Displaying 36426 - 36450 of 74045
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