1,491 research outputs found

    A Functional Description of a Digital Flight Test System for Navigation and Guidance Research in the Terminal Area

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    A guidance, navigation, and control system, the Simulated Shuttle Flight Test System (SS-FTS), when interfaced with existing aircraft systems, provides a research facility for studying concepts for landing the space shuttle orbiter and conventional jet aircraft. The SS-FTS, which includes a general-purpose computer, performs all computations for precisely following a prescribed approach trajectory while properly managing the vehicle energy to allow safe arrival at the runway and landing within prescribed dispersions. The system contains hardware and software provisions for navigation with several combinations of possible navigation aids that have been suggested for the shuttle. The SS-FTS can be reconfigured to study different guidance and navigation concepts by changing only the computer software, and adapted to receive different radio navigation information through minimum hardware changes. All control laws, logic, and mode interlocks reside solely in the computer software

    Flight test pilot evaluation of a delayed flap approach procedure

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    Using NASA's CV-990 aircraft, a delayed flap approach procedure was demonstrated to nine guest pilots from the air transport industry. Four demonstration flights and 37 approaches were conducted under VFR weather conditions. A limited pilot evaluation of the delayed flap procedure was obtained from pilot comments and from questionaires they completed. Pilot acceptability, pilot workload, and ATC compatibility were quantitatively rated. The delayed flap procedure was shown to be feasible, and suggestions for further development work were obtained

    Delayed flap approach procedures for noise abatement and fuel conservation

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    The NASA/Ames Research Center is currently investigating the delayed flap approach during which pilot actions are determined and prescribed by an onboard digital computer. The onboard digital computer determines the proper timing for the deployment of the landing gear and flaps based on the existing winds and airplane gross weight. Advisory commands are displayed to the pilot. The approach is flown along the conventional ILS glide slope but is initiated at a higher airspeed and in a clean aircraft configuration that allows for low thrust and results in reduced noise and fuel consumption. Topics discussed include operational procedures, pilot acceptability of these procedures, and fuel/noise benefits resulting from flight tests and simulation

    Flight performance of a navigation, guidance, and control system concept for automatic approach and landing of space shuttle orbiter

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    Unpowered automatic approaches and landings were conducted to study navigation, guidance, and control problems associated with terminal area approach and landing for the space shuttle vehicle. The flight tests were performed in a Convair 990 aircraft equipped with a digital flight control computer connected to the aircraft control system and displays. The tests were designed to evaluate the performance of a navigation and guidance concept that utilized blended radio/inertial navigation with VOR, DME, and ILS as the ground navigation aids. Results from 36 automatic approaches and landings from 11,300 m (37,000 ft) to touchdown are presented. Preliminary results indicate that this concept may provide sufficient accuracy to accomplish automatic landing of the shuttle orbiter without air-breathing engines

    Flight tests of IFR landing approach systems for helicopters

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    Joint NASA/FAA helicopter flight tests were conducted to investigate airborne radar approaches (ARA) and microwave landing system (MLS) approaches. Flight-test results were utilized to prove NASA with a data base to be used as a performance measure for advanced guidance and navigation concepts, and to provide FAA with data for establishment of TERPS criteria. The first flight-test investigation consisted of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico, using weather/mapping radar, operational pilots, and a Bell 212 helicopter. The second flight-test investigation consisted of IFR MLS approaches at Crows Landing (near Ames Research Center), with a Bell UH-1H helicopter, using NASA, FAA, and operational industry pilots. Tests are described and results discussed

    Visuo-spatial ability in colonoscopy simulator training

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    Visuo-spatial ability is associated with a quality of performance in a variety of surgical and medical skills. However, visuo-spatial ability is typically assessed using Visualization tests only, which led to an incomplete understanding of the involvement of visuo-spatial ability in these skills. To remedy this situation, the current study investigated the role of a broad range of visuo-spatial factors in colonoscopy simulator training. Fifteen medical trainees (no clinical experience in colonoscopy) participated in two psycho-metric test sessions to assess four visuo-spatial ability factors. Next, participants trained flexible endoscope manipulation, and navigation to the cecum on the GI Mentor II simulator, for four sessions within 1 week. Visualization, and to a lesser degree Spatial relations were the only visuo-spatial ability factors to correlate with colonoscopy simulator performance. Visualization additionally covaried with learning rate for time on task on both simulator tasks. High Visualization ability indicated faster exercise completion. Similar to other endoscopic procedures, performance in colonoscopy is positively associated with Visualization, a visuo-spatial ability factor characterized by the ability to mentally manipulate complex visuo-spatial stimuli. The complexity of the visuo-spatial mental transformations required to successfully perform colonoscopy is likely responsible for the challenging nature of this technique, and should inform training- and assessment design. Long term training studies, as well as studies investigating the nature of visuo-spatial complexity in this domain are needed to better understand the role of visuo-spatial ability in colonoscopy, and other endoscopic techniques

    Optimum phase noise reduction and repetition rate tuning in quantum-dot mode-locked lasers

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    Competing approaches exist, which allow control of phase noise and frequency tuning in mode-locked lasers, but no judgement of pros and cons based on a comparative analysis was presented yet. Here, we compare results of hybrid mode-locking, hybrid mode-locking with optical injection seeding, and sideband optical injection seeding performed on the same quantum dot laser under identical bias conditions. We achieved the lowest integrated jitter of 121 fs and a record large radio-frequency (RF) tuning range of 342 MHz with sideband injection seeding of the passively mode-locked laser. The combination of hybrid mode-locking together with optical injection-locking resulted in 240 fs integrated jitter and a RF tuning range of 167 MHz. Using conventional hybrid mode-locking, the integrated jitter and the RF tuning range were 620 fs and 10 MHz, respectively. (C) 2014 AIP Publishing LLC

    Detecting genetic regions associated with height in the native ponies of the British Isles by using high density SNP genotyping

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    Height is an important characteristic in the equine industry, although little is known about its genetic control in native British breeds of ponies. This study aimed to map QTL data with the withers height in four pony breeds native to the British Isles, including two different sections within Welsh Cobs. In this study, a genome-wide analysis approach using the Illumina Equine SNP50 Infinium BeadChip was applied to 105 ponies and cobs. Analysis identified 222 highly significant height-associated SNPs (P < 10-5), among which three SNPs on ECA9 have also been previously reported elsewhere. The highest number of significant SNPs associated to height in the native British horses were located on ECA1, ECA8 and ECA16

    Promoting men’s awareness, self-examination, and help-seeking for testicular disorders: a systematic review of interventions

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    Background: Testicular cancer (TC) is commonly diagnosed among men aged 15-40 years. The incidence of TC is on the rise. Benign testicular disorders such as testicular torsion and epididymitis can lead to testicular ischemia, sepsis, and infertility if left untreated. This systematic review aims to evaluate the effectiveness of studies promoting men’s knowledge and awareness of testicular disorders and/or self-examination, behaviours and/or intentions to examine their testes, and help-seeking behaviours and/or intentions for testicular symptoms. / Methods: Academic Search Complete, Medline, CINAHL, PsychINFO, ERIC, the Cochrane Library, the World Health Organisation International Clinical Trials Registry Platform, Clinicaltrials.gov, Grey Literature Report, and Open Grey were searched for studies published between November 2014 and April 2018. The methodological quality and level of evidence per outcome were assessed. / Results: There were five papers included: two were experimental studies, two were systematic reviews, and one was an integrative review. The majority of the reviewed interventions were successful in increasing men’s awareness of TC and self-examination. Examples include a television show featuring a celebrity with TC, a university campaign, and interactive educational sessions. The impact of the reviewed interventions on health beliefs (i.e. perceived susceptibility, severity, benefits, barriers, and self-efficacy) varied across the reviewed literature. Studies promoting help-seeking for testicular symptoms and awareness of benign testicular disorders were lacking. / Conclusions: This review highlights the importance of evaluating educational interventions aimed at younger men, whilst raising their awareness of testicular disorders and increasing their help-seeking intentions for testicular symptoms. Given the lack of consensus around scheduled testicular self-examination among younger men, clinicians are encouraged to instruct men to familiarise themselves with the look and feel of their own testes and to seek timely medical attention for abnormalities. / Registration: The review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) under the registration number CRD42018093671

    Time resolved pattern evolution in a large aperture laser

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    We have measured quasi-instantaneous transverse patterns in a broad aperture laser. Non-ordered patterns yielding to boundary determined regular structures in progressive time-integrated recording are observed. The linear analysis and numerical integration of the full Maxwell-Bloch equations allow us to interpret the features of the experiment. We show that this system being far from threshold cannot be fully understood with a perturbative model.Comment: 7 pages, 5 GIF figures . To be published in Phys. Rev. Let
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