161,869 research outputs found

    Rotary balances: A selected, annotated bibliography

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    This bibliography on rotary balances contains 102 entries. It is part of NASA's support of the AGARD Fluid Dynamics Panel Working Group 11 on Rotary Balances. This bibliography includes works that might be useful to anyone interested in building or using rotor balances. Emphasis is on the rotary balance rigs and testing techniques rather than the aerodynamic data. Also included are some publications of historical interest which relate to key events in the development and use of rotary balances. The arrangement is chronological by date of publication in the case of reports and by presentation in the case of papers

    Rotorcraft aviation icing research requirements: Research review and recommendations

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    The status of rotorcraft icing evaluation techniques and ice protection technology was assessed. Recommendations are made for near and long term icing programs that describe the needs of industry. These recommended programs are based on a consensus of the major U.S. helicopter companies. Specific activities currently planned or underway by NASA, FAA and DOD are reviewed to determine relevance to the overall research requirements. New programs, taking advantage of current activities, are recommended to meet the long term needs for rotorcraft icing certification

    Overview of methods to analyse dynamic data

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    This book gives an overview of existing data analysis methods to analyse the dynamic data obtained from full scale testing, with their advantages and drawbacks. The overview of full scale testing and dynamic data analysis is limited to energy performance characterization of either building components or whole buildings. The methods range from averaging and regression methods to dynamic approaches based on system identification techniques. These methods are discussed in relation to their application in following in situ measurements: -measurement of thermal transmittance of building components based on heat flux meters; -measurement of thermal and solar transmittance of building components tested in outdoor calorimetric test cells; -measurement of heat transfer coefficient and solar aperture of whole buildings based on co-heating or transient heating tests; -characterisation of the energy performance of whole buildings based on energy use monitoring

    Gait analysis methods in rehabilitation

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    Introduction: Brand's four reasons for clinical tests and his analysis of the characteristics of valid biomechanical tests for use in orthopaedics are taken as a basis for determining what methodologies are required for gait analysis in a clinical rehabilitation context. Measurement methods in clinical gait analysis: The state of the art of optical systems capable of measuring the positions of retro-reflective markers placed on the skin is sufficiently advanced that they are probably no longer a significant source of error in clinical gait analysis. Determining the anthropometry of the subject and compensating for soft tissue movement in relation to the under-lying bones are now the principal problems. Techniques for using functional tests to determine joint centres and axes of rotation are starting to be used successfully. Probably the last great challenge for optical systems is in using computational techniques to compensate for soft tissue measurements. In the long term future it is possible that direct imaging of bones and joints in three dimensions (using MRI or fluoroscopy) may replace marker based systems. Methods for interpreting gait analysis data: There is still not an accepted general theory of why we walk the way we do. In the absence of this, many explanations of walking address the mechanisms by which specific movements are achieved by particular muscles. A whole new methodology is developing to determine the functions of individual muscles. This needs further development and validation. A particular requirement is for subject specific models incorporating 3-dimensional imaging data of the musculo-skeletal anatomy with kinematic and kinetic data. Methods for understanding the effects of intervention: Clinical gait analysis is extremely limited if it does not allow clinicians to choose between alternative possible interventions or to predict outcomes. This can be achieved either by rigorously planned clinical trials or using theoretical models. The evidence base is generally poor partly because of the limited number of prospective clinical trials that have been completed and more such studies are essential. Very recent work has started to show the potential of using models of the mechanisms by which people with pathology walk in order to simulate different potential interventions. The development of these models offers considerable promise for new clinical applications of gait analysis

    Fire design in safety engineering: likely fire curve for people’s safety

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    The present study analyses fire design settings according to Fire Safety Engineering (FSE) for the simulation of fire in civil activities and compares these simulations developed using natural and analytic fire curves. The simulated Heat Rate Release (HRR) curve, appropriately linearized, allows for the estimation of a Likely Fire Curve (LFC). The analytic curves have been introduced for the purpose of evaluating the strength and integrity of the structure, and the adoption of these curves in the fire safety engineering was made following the assumption that the phenomena of major intensity ensure the safe approach of fire design. This argument describes the method adopted for determining a likely fire model that guarantees a greater adherence of the virtualized phenomenon with respect to the potential event. The study showed that the analytic curve, adopted in order to verify the structural strength, in the beginning phases of fire produces fields of temperature and toxic concentrations lower than those obtained by simulation of the Likely Fire Curve. The assumption of the Likely Fire Curve model safeguards exposed people during self-rescue and emergency procedure. The programs used since 2011 for the simulation are FDS (Fire Dynamic Simulator v. 5.4.3) and Smokeview (5.4.8). Comparative analysis was developed using thermo-fluid dynamic parameters (temperature and heat release rate) relevant to the safety of the exposed persons; the case study focuses on children and employees of the nursery. The main result shows that the safety criterion, implicitly included in the analytical fire curves - normally used for fire resistance - doesn’t have the same applicability of a performance based approach on safety evaluation involving people. This paper shows that the Likely Fire Curve assumption involves a thermo-chemical stress more relevant to assessing the safety of exposed people

    Aeronautical Engineering: A special bibliography with indexes, supplement 54

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    This bibliography lists 316 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1975

    Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 156)

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    This bibliography lists 170 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1976
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