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This study evaluates differences between two-year and four-year schools offering a Federal Aviation Administration (FAA) Part 147 aviation maintenance technician program. The actual average test scores were analyzed to determine whether students from four-year university programs were better prepared for the test than students from two-year college or technical school programs. Test scores can be viewed as a direct indication of the quality of the aviation maintenance programs at these schools. The study found that there was no statistically significant difference in the test scores between two-year college and four-year university students taking the FAA examinations. These results support previous studies that found the learning outcomes of two-year and four-year students on general subjects to be comparable. [ABSTRACT FROM AUTHOR]

Examines trends and developments in industrial relations in the U.S. Aerospace update; Meatpacking developments; Grocery agreements; Utility accords; Pulp and paper contracts.

The article discusses the George Palmer Putnam Collection of the Amelia Earhart Papers located at Purdue University in West Lafayette, Indiana. The article details the relationship between Earhart, a U.S. pilot, and Purdue University. According to the article, Earhart and her husband, George Palmer Putnam, met with Purdue president Edward C. Elliot in 1935 and established The Amelia Earhart Fund for Aeronautical Research at Purdue. The article describes the collection and states that the papers cover a time period between 1785 and 1948, encompassing 16.5 cubic feet of materials. According to the article, the papers are classified into seven series including Earhart's flying career, her personal and family life, and artifacts. The article describes the uses and drawbacks of the collection.

Combining data sets from multiple satellite sensors is a powerful method for studying Earth-atmosphere problems. By fusing data, we can utilize the strengths of the individual sensors that may not be otherwise possible. In this paper, we provide the framework for combining level 2 data products, using data from three sensors aboard the National Aeronautics and Space Administration (NASA)'s Terra satellite. These data include top-of-the-atmosphere (TOA) radiative energy fluxes obtained from the Clouds and the Earth's Radiant Energy System (CERES), aerosol optical thickness from the multispectral Moderate Resolution Imaging Spectroradiometer (MODIS), and aerosol properties from the Multi-angle Imaging SpectroRadiometer (MISR). The CERES Single Scanner Footprint (SSF) contains the pixel level CERES TOA fluxes and the level 2 MODIS aerosol data. We specifically focus upon fusing the CERES SSF with the MISR aerosol products. Although this project was undertaken specifically to address aerosol research, the methods employed for fusing data products can be used for other problems requiring synergistic data sets. We present selected case studies over different aerosol regimes and indicate that multisensor information provides value-added information for aerosol research that is not available from a single sensor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical Engineering / Strojniški Vestnik is the property of University of Ljubljana, Faculty of Mechanical Engineering, Journal of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A design project is one of the effective tools to enhance the learning for undergraduate courses. It increases the students' interest in the subject presented and bridges the barrier between the theory and practice. This paper discusses the use of a design project for a junior level mechanical engineering design course. The paper also addresses the philosophy, purpose, and value of the design review process and how it fits into the engineering education. The role of the design review in relation to the general communication skills of engineering graduates is discussed. The project starts by building on the technical and non-technical skills the students have developed in their first two years. Then it expands their skills by utilizing the concepts that are introduced in the theoretical part of the course. Two models are described that represent typical research and applied projects. The main differences between the two models are discussed in terms of the timeline for the main activities of the project and the interrelationship of these activities to the theoretical part of the course. In the first model, the students designed a balance for automotive testing inside the Langley Full Scale Tunnel (LFST) located in the NASA Langley Research Center. This project was done with the cooperation with the Aerospace Engineering Department at Old Dominion University. The second project is to develop a competitive design for a truck-mounted snow plow that must be suitable for mass production. The uniqueness of the first project made it a suitable research project while the competitive nature of the second project made it a good candidate for an applied project. The paper will be of interest to faculty who teach design courses in engineering and technology where the goal is to incorporate a design project that encompasses both technical and non-technical skills. [ABSTRACT FROM AUTHOR]

There has been much recent interest in synthesis algorithms that generate finite state machines from scenarios of intended system behavior. One of the uses of such algorithms is in the transition from requirements scenarios to design. Despite much theoretical work on the nature of these algorithms, there has been very little work on applying the algorithms to practical applications. In this paper, we apply the Whittle&Schumann synthesis algorithm [32] to a component of an air traffic advisory system under development at NASA Ames Research Center. We not only apply the algorithm to generate state machine designs from scenarios but also show how to generate code from the generated state machines using existing commercial code generation tools. The results demonstrate the possibility of generating application code directly from scenarios of system behavior. [ABSTRACT FROM AUTHOR]

An adequate assessment of crisis management failure (and success) requires a validated causal theoy. Without such a theory, any assessment of crisis management performance amounts to little more than a "just so" story. This is the key argument of this paper, which describes how hindsight biases and selective use of social science theory gave rise to a suggestive and convincing - but not necessarily correct - assessment of NASA's role in the Columbia space shuttle disaster (l February 2003). The Columbia Accident Investigation Board (CAIB) identified NASA's organizational culture and safety system as a primary source of failure. The CAIB report reads as a stunning indictment of organizational incompetence: the organization that thrilled the world with the Apollo project had "lost" its safety culture and failed to prevent a preventable disaster. This paper examines the CAIB findings in light of the two dominant theoretical schools that address organizational disasters (normal accident and high reliability theory). It revisits the Columbia shuttle disaster and concludes that the CAIB findings do not sit well with the insights of these schools. [ABSTRACT FROM AUTHOR]

In an effort to support aviation forecasting, the National Weather Service’s Meteorological Development Laboratory (MDL) has recently redeveloped the Localized Aviation Model Output Statistics (MOS) Program (LAMP) system. LAMP is designed to run hourly in NWS operations and produce short-range aviation forecast guidance at 1-h projections out to 25 h. This paper compares and contrasts LAMP ceiling height and visibility forecasts with forecasts produced by the 20-km Rapid Update Cycle model (RUC20), the Weather Research and Forecasting Nonhydrostatic Mesoscale Model (WRF-NMM), and the Short-Range Ensemble Forecast system (SREF). RUC20 and WRF-NMM forecasts of continuous ceiling height and visibility were interpolated to stations and converted into categorical forecasts. These interpolated forecasts were also categorized into instrument flight rule (IFR) or lower conditions and verified against LAMP forecasts at stations in the contiguous United States. LAMP and SREF probabilistic forecasts of ceiling height and visibility from LAMP and the SREF system were also verified. This study demonstrates that for the 0000 and 1200 UTC cycles over the contiguous United States, LAMP station-based categorical forecasts of ceiling height, visibility, and IFR conditions or lower are more accurate than the RUC20 and WRF-NMM ceiling height and visibility forecasts interpolated to stations. Moreover, for the 0900 and 2100 UTC forecast cycles and verification periods studied here, LAMP ceiling height and visibility probabilities exhibit better reliability and skill than the SREF system. [ABSTRACT FROM AUTHOR]

It is essential to maintain global measurements of the earth radiation budget (ERB) from space, the scattered solar and emitted thermal radiative fluxes leaving the planet. These are required for the purpose of validating current climate model predictions of the planet’s future response to anthropogenic greenhouse gas forcing. The measurement accuracy and calibration stability required to resolve the magnitude of model-suggested cloud–climate feedbacks on the ERB have recently been estimated. The suggestion is for ERB data to strive for a calibration stability of ±0.3% decade-1 for scattered solar, ±0.5% decade-1 for emitted thermal, and an overall absolute accuracy of 1 W m-2. The Clouds and the Earth’s Radiant Energy System (CERES) is currently the only satellite program to make global ERB measurements, beginning in January 1998. However, the new climate calibration standards are beyond those originally specified by the NASA CERES program for its edition 2 data release. Furthermore, the CERES instrument optics have been discovered to undergo substantial in-flight degradation because of contaminant issues. This is not directly detectable by using established calibration methods. Hence, user-applied revisions for edition 2 shortwave (SW) data were derived to compensate for this effect, which is described as “spectral darkening.” Also, an entirely new in-flight calibration protocol has been developed for CERES that uses deep convective cloud albedo as a primary solar wavelength stability metric. This is then combined with a sophisticated contamination mobilization/polymerization model. The intention is to assign spectral coloration to any optical degradation occurring to the different CERES Earth observing telescopes. This paper quantifies the stability of revised edition 2 data. It also calculates stability, which the new protocols could give CERES measurements if used. The conclusion is that the edition 2 revisions restore the originally specified stability of CERES SW data. It is also determined that the climate calibration stability goals are reachable by using the new in-flight methodologies presented in this paper. However, this will require datasets of longer than approximately 10 yr. It will also require obtaining regular raster scans of the Moon by all operational CERES instruments. [ABSTRACT FROM AUTHOR]

This paper provides an overview of rotorcraft crashworthiness research being conducted at the National Aeronautics and Space Administration Langley Research Center under sponsorship of the Subsonic Rotary Wing aeronautics program. The research is focused in two areas: development of an externally deployable energy attenuating concept and improved prediction of rotorcraft crashworthiness. The deployable energy absorber (DEA) is a composite honeycomb structure, with a unique flexible hinge design that allows the honeycomb to be packaged and remain flat until needed for deployment. The capabilities of the DEA have been demonstrated through component crush tests and vertical drop tests of a retrofitted fuselage section onto different surfaces or terrain. The research on improved prediction of rotorcraft crashworthiness is focused in several areas including simulating occupant responses and injury risk assessment, predicting multiterrain impact, and utilizing probabilistic analysis methods. A final task is to perform a system-integrated simulation of a full-scale helicopter crash test onto a rigid surface. A brief description of each research task is provided along with a summary of recent accomplishments. [ABSTRACT FROM AUTHOR]

In an effort to contribute to the identification and mitigation of safety risks on civil use airfields, this paper investigates the occurrence and probable causes of airfield incursions caused specifically by ground vehicle operations. Such operations were found to be responsible for nearly 20 per cent of all reported airfield incursions at airports within the USA. The research described in this paper investigated more than 2,000 individual airfield 'vehicle' incursions, as reported to the US Federal Aviation Administration, in an effort to identify their probable causes. Analysis of the data revealed that such incursions may be the result of four primary root causes: driver distraction, inadequate training, lack of situational awareness, or lack of proper communication. As a result of these findings, the authors suggest the targeted implementation of both improved training programmes and enhanced technologies to improve overall situational awareness while operating ground vehicles on an airfield. Proper implementation of technology and enhanced training programmes may be found to reduce these vehicle incursions and thus lead to improved airfield operational safety. [ABSTRACT FROM AUTHOR]

Tests of up to three simultaneously firing 40-cm NASA's Evolutionary Xenon Thrusters took place at NASA Glenn Research Center. In addition to numerous engineering tests, the experiment was instrumented to measure plasma properties in the interacting plumes, charge exchange return current to the active and dormant thrusters, and current and plasma properties at various locations. This paper describes the use of Nascap-2k to calculate plume potentials and charge exchange ion return currents to active and dormant ion optics and to diagnostic probes. Calculations were performed varying the numbers of active thrusters, thruster power levels, and gimbaling. The results were extrapolated to space conditions. Despite several simplifying assumptions, we obtained good agreement with experimental results. No major problems associated with multiple thruster operation were found. [ABSTRACT FROM AUTHOR]

This paper demonstrates the results from a detailed study of the overvoltage protection of a particular 400/150-kV 400-MVA power transformer. The work presented here is based on a real-life power system substation design and data and initiated by Danish TSO Energinet.dk as a consequence of serious transformer overvoltag damage. A simulation model for the entire system consisting of overhead line, transformer, surge arrester, and earth grid has been created in PSCADIEMTDC. The main focus has been put on the earth grid, which has been submodeled in detail in MATLAB using an electromagnetic transient approach based on the thin-wire program made by J. H. Richmond for NASA in 1974. The earth grid model is verified with excellent agreement compared to already published results. The overvoltage performance of the particular case is analyzed, and it shows that the transformers LIWL have probably been exceeded. It is clearly illustrated that the transient performance of the earth grid plays an important role in the overall overvoltage protection system design. [ABSTRACT FROM AUTHOR]

Tests of arcing and current collection in simulated-space-plasma conditions have been performed at the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) in Cleveland, OH, for over 30 years and at the Marshall Space Flight Center (MSFC) in Huntsville, AL, for almost as long. During this period, proper test conditions for an accurate and meaningful space simulation have been worked out, comparisons with actual space performance in spaceflight tests and with real operational satellites have been made, and NASA has achieved the authors' own internal standards for test protocols. It is the purpose of this paper to communicate the test conditions, test procedures, and types of analysis used at the NASA GRC and MSFC to the space environmental testing community at large, to help with international space-plasma arcing-testing standardization. Discussed herein are the neutral gas conditions, plasma densities and uniformity, vacuum chamber sizes, sample sizes and Debye lengths, biasing samples versus self-generated voltages, floating samples versus grounded samples, test electrical conditions, arc detection, preventing sustained discharges during testing, real samples versus idealized samples, validity of low Earth orbit tests for geosynchronous Earth orbit samples, extracting arc threshold information from an arc rate versus voltage tests, snapover, current collection and glows at the positive sample bias, Kapton pyrolysis, thresholds for trigger arcs, sustained arcs, dielectric breakdown and Paschen discharge, tether arcing and testing in very dense plasmas (i.e., thruster plumes), arc mitigation strategies, charging mitigation strategies, models, and analysis of test results. Finally, the necessity of testing will be emphasized, not to the exclusion of modeling, but as part of a complete strategy for determining when and if arcs will occur, and preventing them from occurring in space. [ABSTRACT FROM AUTHOR]

Increasing the capacity of the very high frequency air/ground (A/G) radio system that supports United States air traffic control is a major reason for upgrading the system to a four-slot time-division multiple-access (TDMA) architecture. Since aviation safety requires a dedicated, immediately accessible AJG circuit for each controller, the thousands of circuits in the nationwide system must have compatible frequency/slot assignments that will allow them all to operate simultaneously if necessary. System capacity may be defined as the size to which the system can grow before it will no longer be feasible to find a compatible assignment for every required new circuit. This paper describes a strategy for combining MG circuits into multislot TDMA ‘bundles’ in a way that will enhance capacity by efficiently using available frequencies and slots. To quantify the resultant capacity gain, the authors have applied the strategy in a series of nationwide system growth simulations, noting the numbers of hypothetical future circuit requirements that were met before frequency denials started to become necessary in some cases. Their results indicate that the capacity of the TDMA version of the system would be 2.8-3.7 times that of the present-day AM analog version. [ABSTRACT FROM AUTHOR]

Ice concentration retrieved from spaceborne passive-microwave observations is a prime input to operational sea-ice-monitoring programs, numerical weather prediction models, and global climate models. Atmospheric Environment Service (AES)-York and the Enhanced National Aeronautics and Space Administration Team (NT2) are two algorithms that calculate ice concentration from Special Sensor Microwave/Imager observations. This paper furnishes a comparison between ice concentrations (total, thin, and thick types) output from NT2 and AES-York algorithms against the corresponding estimates from the operational analysis of Radarsat images in the Canadian Ice Service (CIS). A new data fusion technique, which incorporates the actual sensor's footprint, was developed to facilitate this study. Results have shown that the NT2 and AES-York algorithms underestimate total ice concentration by 18.35% and 9.66% concentration counts on average, with 16.8% and 15.35% standard deviation, respectively. However, the retrieved concentrations of thin and thick ice are in much more discrepancy with the operational CIS estimates when either one of these two types dominates the viewing area. This is more likely to occur when the total ice concentration approaches 100 %. If thin and thick ice types coexist in comparable concentrations, the algorithms' estimates agree with CIS's estimates. In terms of ice concentration retrieval, thin ice is more problematic than thick ice. The concept of using a single tie point to represent a thin ice surface is not realistic and provides the largest error source for retrieval accuracy. While AES-York provides total ice concentration in slightly more agreement with CIS's estimates, NT2 provides better agreement in retrieving thin and thick ice concentrations. [ABSTRACT FROM AUTHOR]

The Federal Aviation Administration's effort to automate air traffic control (ATC) requires that the functionality provided today be captured in future systems. We report the first quantitative naturalistic observation of paper flight progress strip interactions during operational use. Strip use was similar in a variety of situations, but some uses varied as a function of altitude, staffing, or the cooperative style used by controller teams. Design of automation should proceed by prioritizing changes based on frequency of use and importance and should ensure that an effective method of interacting with flight information is incorporated. In addition to applied relevance to the ATC domain, the results touch on several theoretical concerns relevant to dynamic environments. Actual and potential applications of this research include the establishment of a database of strip activity and an arsenal of information valuable to system designers. [ABSTRACT FROM AUTHOR]

The Aviation Weather Center (AWC) is responsible for delivering accurate, consistent, and timely weather information for safe and efficient flight across the United States airspace system along with international obligations. One of the key concerns for forecasters is the prediction and monitoring of convection which directly affects air routes as well as ground operations. Lightning observations are a vital component of available observations helping to confirm the presence of convection and verify forecasts. Up to this time the AWC has relied solely on ground-based cloud-to-ground only detection networks. With the upcoming launch of the Geostationary Lightning Mapper (GLM) aboard GOES-R, the AWC has the opportunity to expand the use of lightning observations by observing total lightning (i.e., the combination of both cloud-to-ground and intra-cloud observations). AWC and NASA's Short-term Prediction Research and Transition Center (SPoRT) have collaborated to assess a demonstration GLM product, the pseudo-GLM, derived from ground-based lightning mapping arrays. This collaboration has focused on the utility of using total lightning in aviation weather forecasting in preparation for the GLM instrument. This paper presents several small cases identified by forecasters using the pseudo-GLM data in operations and discusses the role of GLM data in the future. [ABSTRACT FROM AUTHOR]

In the 1960's a controversy arose regarding the safety of navigation standards of jet aircraft over the North Atlantic Ocean, which led to a confrontation between airline owners and pilots. A systems analysis led to a redesigned and improved system which resolved the controversy by giving each side at least as much as it originally requested, in terms of minimizing cost on the one hand and maximizing safety on the other. This paper describes the problem, the controversy, the model, the data collection and reduction, the solution, and the implementation. [ABSTRACT FROM AUTHOR]

Probabilistic Risk Assessment (PRA) was initially adopted and implemented by NASA in the operational phase of human space flight programs and more recently for the next generation human and robotic space explorations as well as the key operational space missions. Since its first use at NASA, PRA has become recognized throughout the agency as a method of assessing complex mission risks as part of an overall approach to assuring safety and mission success. PRA is now included as a requirement during the design phase of both NASA next generation human space systems as well as high priority robotic/operational missions. This paper presents the application of the first comprehensive PRA during the design phase of the Geostationary Operational Environmental Satellite R-Series (GOES-R). This PRA is also unique in that it includes the first quantitative ground system analysis conducted at NASA. The design and operational changes resulting from the GOES-R PRA are discussed in detail in this paper. [ABSTRACT FROM AUTHOR]

This study examines the growth of Systems-Centric Systems Engineering (SCSE) graduate programs in the United States and the status of full-time non-tenure-track faculty (NTTF) members within these programs. Growth is measured by the number of master's and PhD students who graduated from those programs. The annual production of master's degree graduates has grown by a factor of 5 during the period, increasing from 312 in 2001 to 1535 in 2010. Furthermore, the six largest SE programs accounted for more than half of those graduates. The annual production of PhD degrees has risen as well, though not as dramatically. In spite of such growth, less than 50% of SCSE programs hire NTTF, and, among them, the majority of the programs (65%) have four or fewer NTTF. Only 24% of the total faculty employed by SCSE programs in 2010 are NTTF, and most of them (67%) spend the majority of their time teaching; 65% of the respondents identified industrial experience as the most attractive reason for hiring them. Among SCSE programs that produced a high number of master's degree graduates, the ones that started between 2001 and 2005 employed a higher number of NTTF compared to those that started before 2001. The roles of NTTF are compared to those of tenured and tenure-track faculty (TTTF). This paper concludes with recommendations on how to best use NTTF. ©2013 Wiley Periodicals, Inc. Syst Eng 16 [ABSTRACT FROM AUTHOR]

This paper reviews all engine noise research conducted at the National Aeronautics and Space Administration (NASA) Glenn Research Center over the last 70 years. The review includes a historical perspective of the center and the facilities used to conduct the research. Major NASA noise research programs are highlighted, showing their impact on the industry and on the development of aircraft noise reduction technology. Noise reduction trends are discussed, and future aircraft concepts are presented. Results show that, since the 1960s, the average perceived noise level has been reduced by about 20 dB. Studies show that, depending on the size of the airport, the aircraft fleet mix, and the actual growth in air travel, another 15-17 dB is required to achieve NASA's long-term goal of providing technologies to limit objectionable noise to the boundaries of an average airport. [ABSTRACT FROM AUTHOR]

NASA's Constellation Program, formulated in 2005 to achieve the objectives of maintaining American presence in low Earth orbit, returning to the Moon for purpose of establishing an outpost, and exploring Mars and beyond in the first half of the 21st century, was cancelled in 2010 [US Congress, NASA Authorization Act, Public Law 11-267, 2010]. This paper describes the lessons learned developed by the staff of the Constellation Program to advise future programs, as well as program and system engineering managers of similar national efforts. These lessons learned are offered by those who experienced the day-to-day challenges of managing an effort planned as a multidecade undertaking. This effort spanned all 10 NASA Centers, multiple large-scale acquisitions, and required modernizing an infrastructure designed and sized largely for the Apollo program in the 1960s. Moreover, it required leading a workforce generationally removed from the previous human spacecraft launch and entry development challenges. Key lessons learned from the Constellation Program are addressed and cover program elements in which systems engineers provide leadership and/or assistance to program management, including program planning, requirements development, system design methodology, management structure, decision-making, and communications in a national program. ©2012 Wiley Periodicals, Inc. Syst Eng 16: [ABSTRACT FROM AUTHOR]

Copyright of Gerencia Tecnologica Informatica is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper investigates the outcomes of multimarket competition among U.S. scheduled airlines when the interests and positions of the airlines differ in the mutually contested markets. Asymmetry in territorial interests provides multimarket competitors with footholds in important markets of their rivals, which can be used to deter the behavior of the rivals in other markets. Evidence suggests that airlines use footholds in their rivals' important markets (particularly in their hubs) to reduce the competitive intensity of those rivals in the airlines' own important markets (their hubs), and sustain their dominant positions (or spheres of influence) in those markets. [ABSTRACT FROM AUTHOR]

In March 2009, the Obama administration sent a message to senior Pentagon staff instructing them to refrain from using either of the terms ‘Long War’ or ‘Global War on Terror’ and to replace these terms with ‘Overseas Contingency Operations’. The change in tone and, potentially, substance, from the Obama White House by ending the ‘war on terror’ at the rhetorical level suggests a need to shift our academic attention towards developing more appropriate analytical frameworks for examining alternative strategies for countering terrorism. This paper seeks to explore what it terms an emerging risk-based approach being deployed by states. Our framework proposed here deploys the twin concepts of ‘risk bureaucracies’ and risk regulatory regimes (RRRs) in examining terrorist financing and aviation security regulations. [ABSTRACT FROM PUBLISHER]

This paper reports results from field deployments of the Tempest Unmanned Aircraft System, the first of its kind of unmanned aircraft system designed to perform in situ sampling of supercell thunderstorms, including those that produce tornadoes. A description of the critical system components, consisting of the unmanned aircraft, ground support vehicles, communications network, and custom software, is given. The unique concept of operations and regulatory issues for this type of highly nomadic and dynamic system are summarized, including airspace regulatory decisions from the Federal Aviation Administration to accommodate unmanned aircraft system operations for the study of supercell thunderstorms. A review of the system performance and concept of operations effectiveness during flights conducted for the spring 2010 campaign of the VORTEX2 project is provided. These flights resulted in the first-ever sampling of the rear flank gust front and airmass associated with the rear flank downdraft of a supercell thunderstorm by an unmanned aircraft system. A summary of the lessons learned, future work, and next steps is provided. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The Ocean Surface Topography Mission onboard the Jason-2 satellite represents a transition from the Topex/Poseidon and Jason-1 research altimetry missions, operated by NASA and CNES, to an operational mission that now includes NOAA and EUMETSAT. The near real-time (NRT) data production and distribution is shared by NOAA and EUMETSAT. This paper describes how the Jason-2 data are shared within the United States between NOAA and Navy entities. Differences between the NRT products and offline products are assessed to determine if the NRT products are accurate enough to meet the operational needs of wind/wave and sea surface height applications. [ABSTRACT FROM PUBLISHER]

Abstract: In previous papers, the authors developed an active control scheme based on the linear quadratic regulator (LQR) to maintain the separation distance constraints of the NASA benchmark tetrahedron constellation. Two different active control schemes were used to maintain the separation distance constraints, but one control scheme applied to every eccentricity of the NASA benchmark problem. Through this paper, the digital LQR strategy will be developed with this active control scheme to maintain the separation distance conditions of the tetrahedron constellation. The motion of a pair of satellites in an elliptical orbit about the Earth is defined by the linearized Tschauner–Hempel (TH) equations. These equations will be defined discretely in the true anomaly angle for the development of the digital control scheme. In summary, the digital LQR approach will be implemented and studied to determine how this active control scheme maintains the separation distance constraints for different specific sizes of the NASA benchmark tetrahedron constellation. [Copyright &y& Elsevier]

The paper presents an overview of the fundamental research performed in the US in the field of flight structures under the sponsorship of the Air Force Office of Scientific Research (AFOSR). After presenting a general overview of AFOSR, the paper focuses on the structural mechanics program. Three large applications areas are considered: (a) future flight structures; (b) structural sustainment; (c) structural dynamics and vibration control. These three broad areas are covered at various levels of complexity and detail. Currently supported topics are presented and major funding and results are discussed. The paper ends with summary and conclusions. [ABSTRACT FROM AUTHOR]

Radiance Research M903 nephelometers have been operated at remote Australian Outback sites since April 1998. This paper describes the calibration procedures applied to these instruments and reports on the noise performance and other operational issues. It is found that instrument noise leads to a detection limit of ∼0.2 Mm-1 in scattering coefficient at the 95% confidence interval for a 5-min integration. Changes in ambient temperature cause drift with a coefficient of ∼0.06 Mm-1 K-1, leading to a typical diurnal drift of amplitude ∼0.9 Mm-1. Over the 10-yr deployment at an Outback station, the accuracy of the derived scattering coefficient is compromised by drifts in sensitivity and offset, in part related to gross changes in bandpass filter characteristics resulting from environmental degradation. A method is developed to track these changes. An uncertainty analysis suggests that the typical background scattering coefficient of ∼10 Mm-1 can be measured to within 15% at the 95% confidence level. For events where the scattering coefficient is >100 Mm-1, the uncertainty falls to ∼5%. Correction factors are derived for angular truncation error and inlet efficiency for the particular inlet configuration adopted and illustrated via a case study using size distributions guided by collocated NASA Aerosol Robotic Network (AERONET) data. [ABSTRACT FROM AUTHOR]

In January 2004, NASA's twin Mars Exploration Rovers (MERs), Spirit and Opportunity, began searching the surface of Mars for evidence of past water activity. To localize and approach scientifically interesting targets, the rovers employ an onboard navigation system. Given the latency in sending commands from Earth to the Martian rovers (and in receiving return data), a high level of navigational autonomy is desirable. Autonomous navigation with hazard avoidance (AutoNav) is currently performed using a local path planner called GESTALT (grid-based estimation of surface traversability applied to local terrain) that incorporates terrain and obstacle information generated from stereo cameras. GESTALT works well at guiding the rovers around narrow and isolated hazards; however, it is susceptible to failure when clusters of closely spaced, nontraversable rocks form extended obstacles. In May 2005, a new technology task was initiated at the Jet Propulsion Laboratory to address this limitation. Specifically, a version of the Field D* global path planner was integrated into MER flight software, enabling simultaneous local and global planning during AutoNav. A revised version of AutoNav was then uploaded to the rovers during the summer of 2006. In this paper we describe how this integration of global planning into the MER flight software was performed and provide results from both the MER surface system test bed rover and five fully autonomous runs by Opportunity on Mars. © 2009 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Traffic flow management (TFM) allocates the various airport, airspace, and other resources to maintain an efficient traffic flow consistent with safety. TFM is a complex area of research involving the disciplines of operations research, guidance and control, human factors, and software engineering. Hundreds of human operators make TFM decisions that involve tens of thousands of aircraft, en route air traffic control centers, the Federal Aviation Administration's System Command Center, and many airline operation centers. This paper provides an overview of how TFM decisions are made today and challenges facing the system in the future, and reviews modeling and optimization approaches for facilitating system-wide modeling, performance assessments, and system-level optimization of the national airspace system in the presence of both en route and airport capacity constraints. [ABSTRACT FROM AUTHOR]

The U.S. air transportation system faces substantial challenges in implementing new aviation information systems to meet future demand. These challenges need to be understood and addressed in order to successfully meet future system needs. This paper uses a feedback model to describe the processes by which system change occurs. In addition, key issues in the dynamics of system change, with particular emphasis on stakeholder cost-benefit dynamics, and safety approval processes are identified. Overcoming stakeholder barriers and ensuring efficient safety approval and certification process are key enablers to the successful implementation of aviation information systems into the air transportation system. The implementation of Automatic Dependent Surveillance--Broadcast and integration of unmanned aircraft systems into the air transportation system are discussed as examples of current technology-dependent system changes. [ABSTRACT FROM AUTHOR]