4,232 research outputs found

    Sensor failure detection system

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    Advanced concepts for detecting, isolating, and accommodating sensor failures were studied to determine their applicability to the gas turbine control problem. Five concepts were formulated based upon such techniques as Kalman filters and a screening process led to the selection of one advanced concept for further evaluation. The selected advanced concept uses a Kalman filter to generate residuals, a weighted sum square residuals technique to detect soft failures, likelihood ratio testing of a bank of Kalman filters for isolation, and reconfiguring of the normal mode Kalman filter by eliminating the failed input to accommodate the failure. The advanced concept was compared to a baseline parameter synthesis technique. The advanced concept was shown to be a viable concept for detecting, isolating, and accommodating sensor failures for the gas turbine applications

    Sensor failure detection for jet engines

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    Revisions to the advanced sensor failure detection, isolation, and accommodation (DIA) algorithm, developed under the sensor failure detection system program were studied to eliminate the steady state errors due to estimation filter biases. Three algorithm revisions were formulated and one revision for detailed evaluation was chosen. The selected version modifies the DIA algorithm to feedback the actual sensor outputs to the integral portion of the control for the nofailure case. In case of a failure, the estimates of the failed sensor output is fed back to the integral portion. The estimator outputs are fed back to the linear regulator portion of the control all the time. The revised algorithm is evaluated and compared to the baseline algorithm developed previously

    HYTESS: A hypothetical turbofan engine simplified simulation

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    A users manual for a hypothetical turbofan engine simplified simulation is presented. This digital simulation exists as FORTRAN source code. The program is self-contained and was developed to offer those interested in engine dynamics and controls research an efficient, realistic, and easily used engine simulation. The engine is modeled using a state space formulation. Matrix elements within the linear state space structure are nonlinear functions of various engine variables

    Електронний путівник і координатор (Завдання та функції інформаційного ресурсу Науково-видавничої ради НАН України «Наукові публікації і видавнича діяльність»)

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    Purpose: Physical activity (PA) is an important behavior when it comes to preventing or slowing down disablement caused by aging and chronic diseases. It remains unclear whether PA can directly prevent or reduce disability in activities of daily living (ADL). This article presents a meta-analysis of the association between PA and the incidence and progression of basic ADL disability (BADL). Methods: Electronic literature search and cross-referencing of prospective longitudinal studies of PA and BADL in community dwelling older adults (50+) with baseline and follow-up measurements, multivariate analysis and reporting a point estimate for the association. Results: Compared with a low PA, a medium/high PA level reduced the risk of incident BADL disability by 0.51 (95% CI: 0.38, 0.68; p < 001), based on nine longitudinal studies involving 17,000 participants followed up for 3–10 years. This result was independent of age, length of follow-up, study quality, and differences in demographics, health status, functional limitations, and lifestyle. The risk of progression of BADL disability in older adults with a medium/high PA level compared with those with a low PA level was 0.55 (95% CI: 0.42, 0.71; p < 001), based on four studies involving 8500 participants. Discussion: This is the first meta-analysis to show that being physically active prevents and slows down he disablement process in aging or diseased populations, positioning PA as the most effective preventive trategy in preventing and reducing disability, independence and health care cost in aging societies

    Dyadic influence of hope and optimism on patient marital satisfaction among couples with advanced breast cancer

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    PURPOSE: An estimated 10-40 % of breast cancer (BC) patients report negative changes to their partnered relationships. Literature suggests that for these patients, marital satisfaction is related to depression and other quality of life factors which are associated with survivorship and treatment response. However, existing literature does not provide a clear explanation of the factors that strengthen vs. create strain in couples facing cancer. Given the benefits of a satisfying relationship to patient quality of life, it is important to better understand factors that put patients at greater risk for marital difficulties. This study examined the differential and combined roles of hope and optimism among BC patients and their partners on patient marital satisfaction. METHOD: Fifty-six breast cancer patient-partner dyads completed study questionnaires as part of a larger study. Regression analyses were used to examine the main and interaction effects of patient and partner hope and optimism on patient marital satisfaction. RESULTS AND CONCLUSION: Higher patient and partner hope predicted greater patient marital satisfaction, whereas optimism did not. These results are divergent from the literature on optimism and well-being, which shows the importance of studying these two traits concurrently. Interaction effects suggest certain combinations of patient and partner hope and optimism are more beneficial than others for patient marital satisfaction and suggest a dyadic approach is important for investigation of well-being in breast cancer

    Coping with pain in the hip or knee in relation to physical disability in community-living elderly people

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    __Objective__ To investigate the use of pain coping strategies by community-living older people with pain in the hip or knee and the mediating role of coping with pain in the relationship between the chronicity of pain and physical disability. __Methods__ A group of 157 people with pain 'in the last month' was identified. Coping with pain was assessed with the Pain Coping Inventory, physical disability with the Sickness Impact Profile, and household and sport activities with a validated structured interview method. __Results__ People with chronic pain used relatively more 'resting,' and 'reducing demands' as pain coping strategies. Pain chronicity made a significant contribution to physical disability; however, when corrected for other variables in a regression model, no significant partial correlation was found. __Conclusion__ We conclude that pain coping has a mediating role in the relationship between pain chronicity and physical disability. Less use of 'resting' and a physically active lifestyle are independently associated with less physical disability

    Obesity-Induced Colorectal Cancer Is Driven by Caloric Silencing of the Guanylin-GUCY2C Paracrine Signaling Axis.

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    Obesity is a well-known risk factor for colorectal cancer but precisely how it influences risks of malignancy remains unclear. During colon cancer development in humans or animals, attenuation of the colonic cell surface receptor guanylyl cyclase C (GUCY2C) that occurs due to loss of its paracrine hormone ligand guanylin contributes universally to malignant progression. In this study, we explored a link between obesity and GUCY2C silencing in colorectal cancer. Using genetically engineered mice on different diets, we found that diet-induced obesity caused a loss of guanylin expression in the colon with subsequent GUCY2C silencing, epithelial dysfunction, and tumorigenesis. Mechanistic investigations revealed that obesity reversibly silenced guanylin expression through calorie-dependent induction of endoplasmic reticulum stress and the unfolded protein response in intestinal epithelial cells. In transgenic mice, enforcing specific expression of guanylin in intestinal epithelial cells restored GUCY2C signaling, eliminating intestinal tumors associated with a high calorie diet. Our findings show how caloric suppression of the guanylin-GUCY2C signaling axis links obesity to negation of a universal tumor suppressor pathway in colorectal cancer, suggesting an opportunity to prevent colorectal cancer in obese patients through hormone replacement with the FDA-approved oral GUCY2C ligand linaclotide

    Hyper-X Mach 7 Scramjet Design, Ground Test and Flight Results

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    The successful Mach 7 flight test of the Hyper-X (X-43) research vehicle has provided the major, essential demonstration of the capability of the airframe integrated scramjet engine. This flight was a crucial first step toward realizing the potential for airbreathing hypersonic propulsion for application to space launch vehicles. However, it is not sufficient to have just achieved a successful flight. The more useful knowledge gained from the flight is how well the prediction methods matched the actual test results in order to have confidence that these methods can be applied to the design of other scramjet engines and powered vehicles. The propulsion predictions for the Mach 7 flight test were calculated using the computer code, SRGULL, with input from computational fluid dynamics (CFD) and wind tunnel tests. This paper will discuss the evolution of the Mach 7 Hyper-X engine, ground wind tunnel experiments, propulsion prediction methodology, flight results and validation of design methods

    Response Conversion for Improving Comparability of International Physical Activity Data

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    Background: Many questionnaires for measuring physical activity (PA) exist. This complicates the comparison of outcomes. Methods: In 8 European countries, PA was measured in random samples of 600 persons, using the IPAQ as a 'bridge' to historical sets of country-specific questions. We assume that a unidimensional scale of PA ability exists on which items and respondents can be placed, irrespective of country, culture, background factors, or measurement instrument. Response Conversion (RC) based on Item Response Theory (IRT) was used to estimate such a common PA scale, to compare PA levels between countries, and to create a conversion key. Comparisons were made with Eurobarometer (IPAQ) data. Results: Appropriateness of IRT was supported by the existence of a strong first dimension established by principal component analysis. The IRT analysis resulted in 1 common PA scale with a reasonable fit and face validity. However, evidence for cultural bias (Differential Item Functioning, DIF) was found in all IPAQ items. This result made actual comparison between countries difficult. Conclusions: Response Conversion can improve comparability in the field of PA. RC needs common items that are culturally unbiased. Wide-scale use of RC awaits measures that are more culturally invariant (such as international accelerometer data). © 2012 Human Kinetics, Inc
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