Software Tools for Developing and Simulating the NASA LaRC CMF Motion Base

The NASA Langley Research Center (LaRC) Cockpit Motion Facility (CMF) motion base has provided many design and analysis challenges. In the process of addressing these challenges, a comprehensive suite of software tools was developed. The software tools development began with a detailed MATLAB/Simulink model of the motion base which was used primarily for safety loads prediction, design of the closed loop compensator and development of the motion base safety systems1. A Simulink model of the digital control law, from which a portion of the embedded code is directly generated, was later added to this model to form a closed loop system model. Concurrently, software that runs on a PC was created to display and record motion base parameters. It includes a user interface for controlling time history displays, strip chart displays, data storage, and initializing of function generators used during motion base testing. Finally, a software tool was developed for kinematic analysis and prediction of mechanical clearances for the motion system. These tools work together in an integrated package to support normal operations of the motion base, simulate the end to end operation of the motion base system providing facilities for software-in-the-loop testing, mechanical geometry and sensor data visualizations, and function generator setup and evaluation

Evaluating the Performance of the NASA LaRC CMF Motion Base Safety Devices

This paper describes the initial measured performance results of the previously documented NASA Langley Research Center (LaRC) Cockpit Motion Facility (CMF) motion base hardware safety devices. These safety systems are required to prevent excessive accelerations that could injure personnel and damage simulator cockpits or the motion base structure. Excessive accelerations may be caused by erroneous commands or hardware failures driving an actuator to the end of its travel at high velocity, stepping a servo valve, or instantly reversing servo direction. Such commands may result from single order failures of electrical or hydraulic components within the control system itself, or from aggressive or improper cueing commands from the host simulation computer. The safety systems must mitigate these high acceleration events while minimizing the negative performance impacts. The system accomplishes this by controlling the rate of change of valve signals to limit excessive commanded accelerations. It also aids hydraulic cushion performance by limiting valve command authority as the actuator approaches its end of travel. The design takes advantage of inherent motion base hydraulic characteristics to implement all safety features using hardware only solutions

Autonomous Aerobraking Development Software: Phase 2 Summary

NASA has used aerobraking at Mars and Venus to reduce the fuel required to deliver a spacecraft into a desired orbit compared to an all-propulsive solution. Although aerobraking reduces the propellant, it does so at the expense of mission duration, large staff, and DSN coverage. These factors make aerobraking a significant cost element in the mission design. By moving on-board the current ground-based tasks of ephemeris determination, atmospheric density estimation, and maneuver sizing and execution, a flight project would realize significant cost savings. The NASA Engineering and Safety Center (NESC) sponsored Phase 1 and 2 of the Autonomous Aerobraking Development Software (AADS) study, which demonstrated the initial feasibility of moving these current ground-based functions to the spacecraft. This paper highlights key state-of-the-art advancements made in the Phase 2 effort to verify that the AADS algorithms are accurate, robust and ready to be considered for application on future missions that utilize aerobraking. The advancements discussed herein include both model updates and simulation and benchmark testing. Rigorous testing using observed flight atmospheres, operational environments and statistical analysis characterized the AADS operability in a perturbed environment

Le vedute di Pietro Fabris e il collezionismo britannico a Napoli durante il Grand Tour: tempi, modi e formule di un successo

Il lavoro di ricerca condotto nel triennio dottorale è incentrato sul pittore anglo-napoletano Pietro Fabris, attivo a Napoli nella seconda metà del XVIII secolo come autore di vedute e scene di genere. Protetto dall'ambasciatore britannico William Hamilton, Fabris entrò in contatto con i Grand Tourists e con la Corte borbonica, riscuotendo largo consenso a Napoli e in Inghilterra. Esaminando l'evoluzione del fenomeno del Grand Tour a Napoli dal XVII al XVIII secolo, vengono delineate le ragioni e le dinamiche che hanno decretato il successo dei dipinti di Pietro Fabris presso i viaggiatori stranieri, in particolare britannici, mentre attraverso l'analisi di documenti inediti, rinvenuti nell'Archivio Storico del Banco di Napoli e nell'Archivio di Stato di Napoli, sono state ricostruite la vicenda biografica e le relazioni del pittore con acquirenti e collezionisti. La tesi è dunque punto di partenza per studi futuri sul pittore e sul collezionismo di vedute napoletane

Professional Reading

The Swordbearers: Supreme Command in the First World War, and The Theory and Practice of Wa

Saying Goodbye

[ABSTRACT ONLY; NO FULL TEXT] A person lives and then dies, but our memories of a life swim in and out of time and space. In this one-act play I present a family as they prepare for a memorial service. The characters are a matriarch, two adult children, a grandchild and significant other, the deceased, and a delivery person. The visuals are a simple assemblage of tables, chairs and props, and a large video screen upstage. The exploration of characters draws from Ben Highmore's theory of looking at the un-glorious everydayness of a life; we watch as the family members focus on creating the formalities of the memorial to satisfy their own needs. The play ends with a lament that draws from the style of Ben Marcus; the matriarch providing the only emotional memory of the deceased, her utterances stripping away signifiers in language, focusing on her feelings and sensations. The result: a bricolage of what remains of a life: a few objects and conflicting memories.California State University, Northridge. Department of English

Utilising Local Model Neural Network Jacobian Information in Neurocontrol

Student Number : 8315331 - MSc dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built EnvironmentIn this dissertation an efficient algorithm to calculate the differential of the network output with respect to its inputs is derived for axis orthogonal Local Model (LMN) and Radial Basis Function (RBF) Networks. A new recursive Singular Value Decomposition (SVD) adaptation algorithm, which attempts to circumvent many of the problems found in existing recursive adaptation algorithms, is also derived. Code listings and simulations are presented to demonstrate how the algorithms may be used in on-line adaptive neurocontrol systems. Specifically, the control techniques known as series inverse neural control and instantaneous linearization are highlighted. The presented material illustrates how the approach enhances the flexibility of LMN networks making them suitable for use in both direct and indirect adaptive control methods. By incorporating this ability into LMN networks an important characteristic of Multi Layer Perceptron (MLP) networks is obtained whilst retaining the desirable properties of the RBF and LMN approach

Exploration of anogenital distance as a novel fertility phenotype in dairy cattle

Over the last 40 years, there has been an obvious decline in reproductive performance and fertility in dairy cattle, highlighting the importance of genetic improvement in this area. With more recent technological advancements, opportunity arises to identify and incorporate novel fertility traits, with the potential to complement current traits, into breeding objectives in an effort to achieve more substantial genetic gain for fertility. Recently, anogenital distance (AGD), measured as the distance from the centre of the anus to the base of the clitoris, has shown to have an inverse association with measures of fertility in dairy cows. Two studies were conducted to explore the associations between anogenital distance and measures of fertility in a larger population of dairy heifers and cows from Western Canada and the USA. The objectives of the first study (Chapter 3) were to (1) characterize AGD in nulliparous dairy heifers, and (2) determine if an inverse relationship between AGD and fertility, previously found in lactating dairy cows, is also evident in nulliparous heifers. AGD was normally distributed, highly variable, and inversely related with measures of fertility. Heifers with short AGD required fewer services per conception (1.5 ± 0.1 vs. 1.7 ± 0.1; P < 0.01), conceived earlier (14.9 ± 0.2 vs. 15.1 ± 0.2 mo; P < 0.01), and a greater proportion of them became pregnant to first artificial insemination (AI; 58.3 ± 3.0 vs. 49.6 ± 3.1 %; P < 0.001) than their long-AGD counterparts. Moreover, heifers with long AGD had a lower relative risk for pregnancy up to 450 d of life compared with those with short AGD (hazard ratio: 0.59; P < 0.001). This study established that an inverse association between AGD and fertility exists in nulliparous heifers. The second study (Chapter 4) aimed to validate findings that AGD is inversely related to measures of fertility in lactating Holstein cows. A secondary objective of this study was to determine the association between AGD and milk yield. AGD was normally distributed, highly variable, and inversely associated with fertility measures. Cows with short AGD had improved pregnancy to first AI (35.7 ± 2.1 vs. 31.4 ± 2.0 %; P < 0.01) and fewer days open (136.9 ± 4.3 vs. 140.9 ± 4.3 d; P = 0.05) than cows with long AGD. Regardless of parity, cows with short AGD tended to require fewer services per conception (2.3 ± 0.1 vs. 2.4 ± 0.1; P = 0.06) than their long-AGD counterparts, but cumulative pregnancy risks up to 150 and 250 DIM did not differ between AGD categories. Anogenital distance had a weak positive association (r = 0.04; P < 0.01) with 305-d mature equivalent milk yield. The results of this study confirm an inverse relationship between AGD and measures of fertility in lactating cows, validating previous findings, with no evidence of parity effects. Moreover, results indicate that the phenotypic selection for AGD will not cause a substantial decline in milk production. Overall, results from this Master’s thesis research provide further insight into AGD and its associations with fertility on a larger scale, lending further support for AGD to become an indicator of fertility and a possible management tool in future selection programs

Addition of hip exercises to treatment of patellofemoral pain syndrome: A meta-analysis

AIM: To determine if the addition of hip-strengthening exercises decreases pain and improves function in patients with patellofemoral pain syndrome. METHODS: The authors completed a systematic review searching eight databases (i.e. , PubMed, Cochrane, CINHAL, MEDLINE, SportsDiscus, EMBASE, APTA Hooked on Evidence, and PEDro). Two independent reviewers screened and excluded studies if they did not meet the following inclusion criteria: subjects had a primary diagnosis of patellofemoral pain syndrome (PFPS), intervention group included hip-strengthening exercises, control group included a traditional physical therapy intervention, study included outcome measures of pain and/or function, study used a randomized controlled trial design, PEDro score was ≥ 7, and study was published in a peer-reviewed journal. Primary outcome measures were subjective scales of pain and function. These measures were converted to standardized mean difference [effect size (ES)], and a random-effects model was used to calculate the overall ES. RESULTS: Two hundred eighty-three studies were screened for inclusion in our meta-analysis. Nine studies were deemed suitable for data extraction and analysis. A total of 426 subjects were used in the nine studies. Overall, there was a significant positive effect of hip-strengthening exercises on measures of pain and function in subjects with PFPS (ES = 0.94, P = 0.00004). None of the individual studies had a negative ES, with study ES ranging from 0.35 to 2.59. Because of the high degree of between-study variance (I 2 = 76%; Q = 34.0, P \u3c 0.001), subgroup meta-analyses and meta-regressions were performed. None of the potential moderator variables that were investigated (e.g. , outcome type, hip region targeted, duration of treatment) could explain a significant amount of the between-study variance in ES (P ≥ 0.23). CONCLUSION: Overall, the addition of hip-strengthening exercises to traditional physical therapy produced greater improvements in measures of pain and function

Burden of disease resulting from lead exposure at toxic waste sites in Argentina, Mexico and Uruguay

Background: Though lead contaminated waste sites have been widely researched in many high-income countries, their prevalence and associated health outcomes have not been well documented in low- and middle-income countries. Methods: Using the well-established health metric disability-adjusted life year (DALY) and an exposure assessment method developed by Chatham-Stephens et al., we estimated the burden of disease resulting from exposure to lead at toxic waste sites in three Latin American countries in 2012: Argentina, Mexico and Uruguay. Toxic waste sites identified through Pure Earth’s Toxic Sites Identification Program (TSIP) were screened for lead in both biological and environmental sample media. Estimates of cardiovascular disease incidence and other outcomes resulting from exposure to lead were utilized to estimate DALYs for each population at risk. Results: Approximately 316,703 persons in three countries were at risk of exposure to pollutants at 129 unique sites identified through the TSIP database. Exposure to lead was estimated to result in between 51,432 and 115,042 DALYs, depending on the weighting factor used. The estimated burden of disease caused by exposure to lead in this analysis is comparable to that estimated for Parkinson’s disease and bladder cancer in these countries. Conclusions: Lead continues to pose a significant public health risk in Argentina, Mexico, and Uruguay. The burden of disease in these three countries is comparable with other widely recognized public health challenges. Knowledge of the relatively high number of DALYs associated with lead exposure may be used to generate support and funding for the remediation of toxic waste sites in these countries and others