Fault detection, identification and accommodation techniques for unmanned airborne vehicles

Unmanned Airborne Vehicles (UAV) are assuming prominent roles in both the commercial and military aerospace industries. The promise of reduced costs and reduced risk to human life is one of their major attractions, however these low-cost systems are yet to gain acceptance as a safe alternate to manned solutions. The absence of a thinking, observing, reacting and decision making pilot reduces the UAVs capability of managing adverse situations such as faults and failures. This paper presents a review of techniques that can be used to track the system health onboard a UAV. The review is based on a year long literature review aimed at identifying approaches suitable for combating the low reliability and high attrition rates of today’s UAV. This research primarily focuses on real-time, onboard implementations for generating accurate estimations of aircraft health for fault accommodation and mission management (change of mission objectives due to deterioration in aircraft health). The major task of such systems is the process of detection, identification and accommodation of faults and failures (FDIA). A number of approaches exist, of which model-based techniques show particular promise. Model-based approaches use analytical redundancy to generate residuals for the aircraft parameters that can be used to indicate the occurrence of a fault or failure. Actions such as switching between redundant components or modifying control laws can then be taken to accommodate the fault. The paper further describes recent work in evaluating neural-network approaches to sensor failure detection and identification (SFDI). The results of simulations with a variety of sensor failures, based on a Matlab non-linear aircraft model are presented and discussed. Suggestions for improvements are made based on the limitations of this neural network approach with the aim of including a broader range of failures, while still maintaining an accurate model in the presence of these failures

Characterizing and Quantifying Night Sky Brightness in Utah and Arizona

As part of a Research Experience for Undergraduates (REU) program with the National Optical Astronomy Observatory (NOAO), I (with mentor Dr. Constance Walker of NOAO) characterized light pollution in and near Tucson, Arizona using eight Sky Quality Meters (SQMs). In order to analyze the data in a consistent way for comparison, we created a standard procedure for reduction and analysis using python and MATLAB. The series of python scripts and MATLAB codes to remove faulty data and examine specifically anthropogenic light pollution and illustrate how the light pollution changes in relation to time, distance from the city, and airglow. Data are then analyzed by a recently developed sky brightness model created by Dan Duriscoe of the U.S. National Park Service. To quantify the measurements taken by SQMs, we tested the wavelength sensitivity of the devices used for the data collection. The findings from the laboratory testing have prompted innovations for the SQMs as well as given a sense of how data gathered by these devices should be treated. Dr. Shane Larson and I are implementing findings and procedures at Utah State University (USU), along with equipment acquired through the Undergraduate Research and Cre- ative Opportunities (URCO) grant to create a light-map of the university campus and surrounding city. Addi- tionally, the luminosity output of outdoor light fixtures will be analyzed via a Pocket Lux Light Meter. As USU has a sustainability program, Blue Goes Green, that has already implemented lighting codes, the goal of this project is the work with the collegiate administration to renovate old lighting fixtures

A randomized, double-blind, placebo-controlled, crossover study to assess the immediate effect of sublingual glyceryl trinitrate on the ankle brachial pressure index, claudication, and maximum walking distance of patients with intermittent claudication

AbstractPurpose:The goal of the present study was to assess the immediate effect of sublingual glyceryl trinitrate (GTN) in patients with intermittent claudication. Methods: We conducted a randomized, double-blind, placebo-controlled crossover study. Inclusion criteria consisted of history of intermittent claudication, resting ankle brachial pressure index (ABPI) of 1.00 or less, a 20% or greater fall in ABPI after exercise, and maximum walking distance (MWD) of less than 250 m. Patients already receiving nitrates were excluded. In study 1, patients (n = 25) underwent a standard exercise test after randomization to receive either 800 μg of sublingual GTN or placebo. The postexercise ABPI was recorded. Then, the crossover portion of the study was performed. In study 2, patients (n = 22) had their claudication distance and MWD measured. They then were randomized to receive either GTN or placebo spray, and the exercise test was repeated, with the claudication distance and MWD recorded, followed by the crossover portion of the study. Statistical analysis was performed with the Wilcoxon matched pairs signed ranks test and the Mann-Whitney U test. Results:In study 1, the median postexercise ABPIs for placebo and GTN were 0.29 and 0.36 (P = .0001). In study 2, the median claudication distance for both placebo and GTN groups was 70 m (P = .59). The median MWD for the placebo and GTN groups was 105 and 125 m (P = .0084) Conclusion: GTN can decrease the fall in ABPI after exercise and increase the MWD. (J Vasc Surg 1998;28:895-900.

Are three contact efforts really reflective of a repeated high-intensity effort bout?

The use of 3 or more efforts (running and contact), separated by short recovery periods, is widely used to define a 'repeated high-intensity effort' (RHIE) bout in rugby league. It has been suggested that due to fatigue, players become less effective after RHIE bouts; however, there is little evidence to support this. This study determined whether physical performance is reduced after performing 1, 2, or 3 efforts with minimal recovery. Twelve semiprofessional rugby league players (age: 24.5 ± 2.9 years) competed in 3 'off-side' small-sided games (2 × 10-minute halves) with a contact bout performed every 2 minutes. The rules of each game were identical except for the number of contact efforts performed in each bout. Players performed 1, 2, or 3 × 5-second wrestling bouts in the single-, double- and triple-contact game, respectively. Movement demands of each game were monitored using global positioning system units. From the first to the second half, there were trivial reductions in relative distance during the single-contact game (ES -0.13 ± 0.12), small reductions during the double-contact game (ES -0.47 ± 0.24), and moderate reductions during the triple-contact game (ES -0.74 ± 0.27). These data show that running intensity is progressively reduced as the number of contact efforts per bout is increased. Targeting defensive players and forcing them to perform 2 or more consecutive contact efforts is likely to lead to greater reductions in running intensity. Conditioning performing multiple contact efforts while maintaining running intensity should therefore be incorporated into training for contact team sports

SuperCam, a 64-pixel heterodyne imaging array for the 870 micron atmospheric window

We report on the development of SuperCam, a 64 pixel, superheterodyne camera designed for operation in the astrophysically important 870 micron atmospheric window. SuperCam will be used to answer fundamental questions about the physics and chemistry of molecular clouds in the Galaxy and their direct relation to star and planet formation. The advent of such a system will provide an order of magnitude increase in mapping speed over what is now available and revolutionize how observational astronomy is performed in this important wavelength regime. Unlike the situation with bolometric detectors, heterodyne receiver systems are coherent, retaining information about both the amplitude and phase of the incident photon stream. From this information a high resolution spectrum of the incident light can be obtained without multiplexing. SuperCam will be constructed by stacking eight, 1x8 rows of fixed tuned, SIS mixers. The IF output of each mixer will be connected to a low-noise, broadband MMIC amplifier integrated into the mixer block. The instantaneous IF bandwidth of each pixel will be ~2 GHz, with a center frequency of 5 GHz. A spectrum of the central 500 MHz of each IF band will be provided by the array spectrometer. Local oscillator power is provided by a frequency multiplier whose output is divided between the pixels by using a matrix of waveguide power dividers. The mixer array will be cooled to 4K by a closed-cycle refrigeration system. SuperCam will reside at the Cassegrain focus of the 10m Heinrich Hertz telescope (HHT). A prototype single row of the array will be tested on the HHT in 2006, with the first engineering run of the full array in late 2007. The array is designed and constructed so that it may be readily scaled to higher frequencies.Comment: 12 pages, 14 figures, to be published in the Proceedings of SPIE Vol. 6275, "Astronomical Telescopes and Instrumentation, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III

An Experimental Investigation of the Role of Collaboration in the Evolution of Communication Systems

Imitation alone cannot explain language evolution. Two additional ingredients have been proposed that may help explain the evolution of language systems: learning biases and social collaboration. An experimental method was developed that isolated the roles of collaboration and learning biases in the development of novel communication systems. Participants played a Pictionary-like task to develop ad hoc graphical communication systems in one of two conditions: one in which they interacted with a partner (Interaction condition), and one in which they received the same images from a “pseudo-partner” but did not interact (PseudoInteraction condition). Comparison of the resultant communication systems showed that the Interaction condition yielded higher identification accuracy, greater refinement of graphical signs and more alignment on a set of shared graphical signs (in fact, graphical alignment did not occur at all in the Pseudo-Interaction condition). Thus, collaboration plays a crucial role in the evolution of human communication systems

Pharmacists' Perspectives on the Use of My Health Record

Background: My Health Record (MHR) is a relatively new nationwide Australian digitalhealth record system accessible by patients and a range of healthcare professionals. Pharmacists willbe key contributors and users of the MHR system, yet little is known about the perceived barriers andbenefits of use. (2) Objective: To explore pharmacists’ perspectives related to potential benefits andbarriers associated with use of MHR. (3) Methods: An online survey was developed and face-validated.The survey was advertised to Australian pharmacists on pharmacy professional bodies’ websites. Thiswas a cross-sectional study using an anonymous questionnaire. Descriptive statistics were used todescribe the distribution of the data. Chi-square, Kendall’s tau coefficient (tau-c) and Kruskal–Wallistests were used to examine the relationships where appropriate. (4) Results: A total of 63 pharmacistscompleted the survey. The majority of respondents worked in a metropolitan area (74%), and themost common workplace setting was community pharmacy (65%). Perceived benefits identifiedby responders include that the use of MHR would help with continuity of care (90%), and that itwould improve the safety (71%) and quality (75%) of care they provided. Importantly, more thanhalf of pharmacists surveyed agreed that MHR could reduce medication errors during dispensing(57%) and could improve professional relationships with patients (57%) and general practitioners(59%). Potential barriers identified by pharmacists included patients’ concerns about privacy (81%),pharmacists’ own concern about privacy (46%), lack of training, access to and confidence in using thesystem. Sixty six percent of respondents had concerns about the accuracy of information containedwithin MHR, particularly among hospital and general practice pharmacists (p = 0.016) and almosthalf (44%) had concerns about the security of information in the system, mainly pharmacists workingat general practice and providing medication review services (p= 0.007). Overall satisfaction withMHR varied, with 48% satisfied, 33% neither satisfied nor dissatisfied, and 19% dissatisfied, witha higher satisfaction rate among younger pharmacists (p = 0.032). (5) Conclusions: Pharmacistsconsidered that the MHR offered key potential benefits, notably improving the safety and quality ofcare provided. To optimize the use of MHR, there is a need to improve privacy and data securitymeasures, and to ensure adequate provision of user support and education surrounding the ability tointegrate use of MHR with existing workflows and software