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The FAA AWRP oceanic weather program development team

Summary

Remote, oceanic regions have few, if any, high resolution weather products that indicate the current or future locations of aviation hazards such as volcanic ash, convection, turbulence, icing or adverse headwinds. Moreover, oceanic regions present unique challenges due to severely limited data availability, the long duration of transoceanic flights and the difficulty of transmitting critical information into the cockpit. In 2001, the Oceanic Weather Program Development Team (OWPDT; Herzegh et al. 2002) was organized within the Federal Aviation Administration (FAA) Aviation Weather Research Program (AWRP) to focus on resourceful methods for overcoming these limitations through the use of a diverse range of satellite observations, global model results and satellite-based communications. Resulting products focus on the needs of pilots, dispatchers, air traffic managers and forecasters within the oceanic aviation community. The team is a leader in the inflight display of weather products and will continue to develop new displays as products become available.
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Summary

Remote, oceanic regions have few, if any, high resolution weather products that indicate the current or future locations of aviation hazards such as volcanic ash, convection, turbulence, icing or adverse headwinds. Moreover, oceanic regions present unique challenges due to severely limited data availability, the long duration of transoceanic flights and...

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250 mW, 1.5 um monolithic passively mode-locked slab-coupled optical waveguide laser

Published in:
Opt. Lett., Vol. 31, No. 2, January 15, 2006, pp. 223-225.

Summary

We report the demonstration of a 1.5 um InGaAsP mode-locked slab-coupled optical waveguide laser (SCOWL) producing 10 ps pulses with energies of 58 pJ and average output powers of 250 mW at a repetition rate of 4.29 GHz. To the best of our knowledge, this is the first passively mode-locked slab-coupled optical waveguide laser. The large mode and low confinement factor of the SCOWL architecture allows the realization of monolithic mode-locked lasers with high output power and pulse energy. The laser output is nearly diffraction limited with M2 values less than 1.2 in both directions.
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Summary

We report the demonstration of a 1.5 um InGaAsP mode-locked slab-coupled optical waveguide laser (SCOWL) producing 10 ps pulses with energies of 58 pJ and average output powers of 250 mW at a repetition rate of 4.29 GHz. To the best of our knowledge, this is the first passively mode-locked...

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Safety analysis for advanced separatation concepts

Published in:
Air Traffic Control Q., Vol. 14, No. 1, 2006, pp. 5-24.

Summary

Advanced separation assurance concepts involving higher degrees of automation must meet the challenge of maintaining safety in the presence of inevitable subsystem faults, including the complete failure of the supporting automation infrastructure. This paper examines the types of design features and safeguards that might be used to preserve safety in a highly automated environment. The Advanced Airspace Concept (AAC) being developed by NASA is used as the basis for a fault-tree analysis. Multiple layers of protection, with carefully specified fault management strategies, appear to be important to achieving the desired level of safety.
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Summary

Advanced separation assurance concepts involving higher degrees of automation must meet the challenge of maintaining safety in the presence of inevitable subsystem faults, including the complete failure of the supporting automation infrastructure. This paper examines the types of design features and safeguards that might be used to preserve safety in...

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Engineering of the electrocapillary behavior of electrolyte droplets on thin fluoropolymer films

Published in:
Langmuir, Vol. 22, No. 13, 20 June 2006, pp. 5690-5696.

Summary

This study presents methods for engineering the electrocapillary behavior of fluoropolymer surfaces through the use of surfactants and an external insulating liquid. By the scaling of the appropriate surface energies, electrocapillary behavior is obtained at a record low voltage, with contact angle changes in excess of 100[degrees] at 4 V. A consistent description of electrocapillary saturation is presented, identifying three separate regimes: breakdown, thermodynamic instability, and relaxation. Methods for identifying and mitigating some of the saturation behaviors are discussed. Finally, the parameters influencing the observed voltage of zero charge are summarized.
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Summary

This study presents methods for engineering the electrocapillary behavior of fluoropolymer surfaces through the use of surfactants and an external insulating liquid. By the scaling of the appropriate surface energies, electrocapillary behavior is obtained at a record low voltage, with contact angle changes in excess of 100[degrees] at 4 V...

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The identification and verification of hazardous convective cells over oceans using visible and infrared satellite observations

Summary

Three algorithms based on geostationary visible and infrared (IR) observations, are used to identify convective cells that do (or may) present a hazard to aviation over the oceans. The algorithms were developed at the Naval Research Laboratory (NRL), National Center for Atmospheric Research (NCAR), and Aviation Weather Center (AWC). The performance of the algorithms in detecting potentially hazardous cells is determined through verification based upon data from National Aeronautical and Space Administration (NASA) Tropical Rainfall Measuring Mission (TRMM) satellite observations of lightning and radar reflectivity, which provide internal information about the convective cells. The probability of detection of hazardous cells using the satellite algorithms can exceed 90% when lightning is used as a criterion for hazard, but the false alarm ratio with all three algorithms is consistently large (~40%), thereby exaggerating the presence of hazardous conditions. This shortcoming results in part from limitations resulting from the algorithms' dependence upon visible and IR observations, and can be traced to the widespread prevalence of deep cumulonimbi with weak updrafts but without lightning, whose origin is attributed to pronounced departures from non-dilute ascent.
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Summary

Three algorithms based on geostationary visible and infrared (IR) observations, are used to identify convective cells that do (or may) present a hazard to aviation over the oceans. The algorithms were developed at the Naval Research Laboratory (NRL), National Center for Atmospheric Research (NCAR), and Aviation Weather Center (AWC). The...

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pMapper: automatic mapping of parallel Matlab programs

Published in:
Proc. of the HPCM (High Performance Computing Modernization), Users Group Conf., 2005, 27-30 June 2005, pp. 254-261.

Summary

Algorithm implementation efficiency is key to delivering high-performance computing capabilities to demanding, high throughput DoD signal and image processing applications and simulations. Significant progress has been made in compiler optimization of serial programs, but many applications require parallel processing, which brings with it the difficult task of determining efficient mappings of algorithms to multiprocessor computers. The pMapper infrastructure addresses the problem of performance optimization of multistage MATLAB applications on parallel architectures. pMapper is an automatic performance tuning library written as a layer on top of pMatlab. pMatlab is a parallel Matlab toolbox that provides MATLAB users with global array semantics. While pMatlab abstracts the message-passing interface, the responsibility of generating maps for numerical arrays still falls on the user. A processor map for a numerical array is defined as an assignment of blocks of data to processing elements. Choosing the best mapping for a set of numerical arrays in a program is a nontrivial task that requires significant knowledge of programming languages, parallel computing, and processor architecture. pMapper automates the task of map generation, increasing the ease of programming and productivity. In addition to automating the mapping of parallel Matlab programs, pMapper could be used as a mapping tool for embedded systems. This paper addresses the design details of the pMapper infrastructure and presents preliminary results.
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Summary

Algorithm implementation efficiency is key to delivering high-performance computing capabilities to demanding, high throughput DoD signal and image processing applications and simulations. Significant progress has been made in compiler optimization of serial programs, but many applications require parallel processing, which brings with it the difficult task of determining efficient mappings...

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Mach-Zehnder interferometry in a strongly driven superconducting qubit

Published in:
Sci., Vol. 310, No. 5754, 9 December 2005, pp. 1653-1657.

Summary

We demonstrate Mach-Zehnder-type interferometry in a superconducting flux qubit. The qubit is a tunable artificial atom, the ground and excited states of which exhibit an avoided crossing. Strongly driving the qubit with harmonic excitation sweeps it through the avoided crossing two times per period. Because the induced Landau-Zener transitions act as coherent beamsplitters, the accumulated phase between transitions, which varies with microwave amplitude, results in quantum interference fringes for n = 1 to 20 photon transitions. The generalization of optical Mach-Zehnder interferometry, performed in qubit phase space, provides an alternative means to manipulate and characterize the qubit in the strongly driven regime.
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Summary

We demonstrate Mach-Zehnder-type interferometry in a superconducting flux qubit. The qubit is a tunable artificial atom, the ground and excited states of which exhibit an avoided crossing. Strongly driving the qubit with harmonic excitation sweeps it through the avoided crossing two times per period. Because the induced Landau-Zener transitions act...

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Nitride-based UV Geiger-Mode avalanche photodiodes

Published in:
2005 Int. Semiconductor Device Research Symp., 7-9 December 2005.

Summary

III-N materials currently enjoy a predominant role in the formation of solid-state light emitters for [lamda]
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Summary

III-N materials currently enjoy a predominant role in the formation of solid-state light emitters for [lamda]

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CMOS detector technology

Published in:
Exp. Astron., Vol. 19, No. 1-3, 2005, pp. 111-34.
Topic:

Summary

An entry level overview of state-of-the-art CMOS detector technology is presented. Operating principles and system architecture are explained in comparison to the well-established CCD technology, followed by a discussion of important benefits of modern CMOS-based detector arrays. A number of unique CMOS features including different shutter modes and scanning concepts are described. In addition, sub-field stitching is presented as a technique for producing very large imagers. After a brief introduction to the concept of monolithic CMOS sensors, hybrid detectors technology is introduced. A comparison of noise reduction methods for CMOS hybrids is presented. The final sections review CMOS fabrication processes for monolithic and vertically integrated image sensors.
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Summary

An entry level overview of state-of-the-art CMOS detector technology is presented. Operating principles and system architecture are explained in comparison to the well-established CCD technology, followed by a discussion of important benefits of modern CMOS-based detector arrays. A number of unique CMOS features including different shutter modes and scanning concepts...

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A taxonomy of buffer overflows for evaluating static and dynamic software testing tools

Published in:
NIST Workshop on Software Security, Assurance Tools, Techniques, and Metrics, 7-8 November 2005.

Summary

A taxonomy that uses twenty-two attributes to characterize C-program overflows was used to construct 291 small C-program test cases that can be used to diagnostically determine the basic capabilities of static and dynamic analysis buffer overflow detection tools. Attributes in the taxonomy include the buffer location (e.g. stack, heap, data region, BSS, shared memory); scope difference between buffer allocation and access; index, pointer, and alias complexity when addressing buffer elements; complexity of the control flow and loop structure surrounding the overflow; type of container the buffer is within (e.g. structure, union, array); whether the overflow is caused by a signed/unsigned type error; the overflow magnitude and direction; and whether the overflow is discrete or continuous. As an example, the 291 test cases were used to measure the detection, false alarm, and confusion rates of five static analysis tools. They reveal specific strengths and limitations of tools and suggest directions for improvements.
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Summary

A taxonomy that uses twenty-two attributes to characterize C-program overflows was used to construct 291 small C-program test cases that can be used to diagnostically determine the basic capabilities of static and dynamic analysis buffer overflow detection tools. Attributes in the taxonomy include the buffer location (e.g. stack, heap, data...

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