977 research outputs found

    Control System Optimization for Saturn 5 Launch Vehicles Using Gradient Techniques Final Report

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    Control system optimization for Saturn 5 launch vehicles using gradient technique

    The application of optimal control technqiues to advanced manned missions, volume 1

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    Two problems are presented in the area of optimal control and its application to the design of attitude control systems for advanced complex aerospace vehicles. The problems discussed are specification of performance criteria in terms of structural load minimization and/or maximum orbital payload injection requirements of the controlled vehicle; and formulation and solution of the optimization problem such that practical control systems are obtained

    The application of optimal control techniques to advanced manned missions, volume 2

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    The hybrid optimization techique for attitude control design is described in detail. The technque is capable of optimizing an n-dimensional adjustable parameter vector, but a 1-dimensional vector is used as an example to explain the procedure. This permits an easier explanation as opposed to a multidimensional case. The procedure used to derive the perturbation equations of motion describing the 6-DOF shuttle ascent phase is presented. These equations were programmed on the EAI 8800 analog computer to describe the perturbations of the shuttle vehicle from a nominal zero lift trajectory due to wind disturbances. Included are the control system equations, trim equations, and wind angle of attack equations. Analog wiring diagrams, raw data and time-varying coefficients, and state variable responses during shuttle ascent are also considered

    'Diet and lifestyle' in the management of dyslipidaemia and prevention of CVD - Understanding the level of knowledge and interest of European Atherosclerosis Society members.

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    Abstract To better understand the level of knowledge and interest in 'diet and lifestyle' for cholesterol management and CVD prevention, European Atherosclerosis Society (EAS) members were invited to take part in an online survey. In total, 269 EAS members participated of which 64 (24%) were students/postdocs, 102 (38%) researchers involved with CVD-related research and 103 (38%) doctors and clinicians who directly interact with patients. All (99%) of the participants either agreed or strongly agreed that 'diet and lifestyle' have a role to play in cholesterol management, with 80% indicating that 'diet and lifestyle' is very or extremely important. Of the clinicians, 75% indicated that their patients voluntarily ask for 'diet and lifestyle' advice and over 80% said they continuously provide 'diet and lifestyle advice' to their patients. Of the surveyed clinicians, 91% feel sufficiently educated and confident to provide expert advice and over 90% recommend medication, diet change, frequent exercise and smoking cessation to their patients. In view of more specific dietary advice, clinicians reportedly recommend a 'Mediterranean diet', and advise to avoid high-fat foods, and to increase intake of high-fibre foods. Interestingly, smoking cessation and alcohol avoidance were mentioned less frequently. In view of educational needs, over half of the surveyed EAS members use the internet and 'guidelines' to learn about 'diet and lifestyle' in relation to cholesterol and CVD risk management. Clinicians tend to use 'guidelines' more often, while students/postdocs tend to use the internet significantly more than clinicians and CVD researchers. Regarding unmet needs for educational tools addressing specifically 'diet and lifestyle', clinicians feel that patient-oriented leaflets and pocket guidelines would be most beneficial materials to introduce, while students/postdocs would prefer an app. In summary, the role of 'diet and lifestyle' as a cornerstone of cholesterol management and CVD risk prevention seems well recognised amongst EAS members surveyed

    Nonlinear modeling of SFRC beam using multilinear softening function obtained by inverse analysis

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    The modeling of steel fiber reinforced concrete (SFRC) is a challenging task in comparison with the conventional reinforced concrete structures. Softening functions used to numerically reproduce SFRC fracture need to describe the effects associated with the post-cracking residual strength induced by the fibers in the concrete matrix. In order to do this, multilinear softening functions can be used to consider these effects. The work presents the results of a study in which the behavior of a SFRC beam tested in four-point bending test is compared with the responses obtained in nonlinear simulations using the finite element method. Multilinear softening functions are obtained through an inverse analysis technique, aiming to reproduce the phenomena of appearance and propagation of cracks. The simulations were performed using ATENA/GiD software. The technique adopted to find the softening function of SFRC allowed to reproduce, with a good agreement, the behavior reported experimentally596CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES140135 / 2019-701-P-01879-201

    The Effect of Inlet Pressure and Temperature on the Efficiency of a Single-stage Impulse Turbine Having an 11.0-inch Pitch-line Diameter Wheel

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    Efficiency tests have been conducted on a single-stage impulse engine having an 11-inch pitch-line diameter wheel with inserted buckets and a fabricated nozzle diaphragm. The tests were made to determine the effect of inlet pressure, Inlet temperature, speed, and pressure ratio on the turbine efficiency. An analysis is presented that relates the effect of inlet pressure and temperature to the Reynolds number of the flow. The agreement between the analysis and the experimental data indicates that the changes in turbine efficiency with Inlet pressure and temperature may be principally a Reynolds number effect

    Arthropods of the great indoorssuburban homes:characterizing diversity inside urban and suburban homes

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    Although humans and arthropods have been living and evolving together for all of our history, we know very little about the arthropods we share our homes with apart from major pest groups. Here we surveyed, for the first time, the complete arthropod fauna of the indoor biome in 50 houses (located in and around Raleigh, North Carolina, USA). We discovered high diversity, with a conservative estimate range of 32–211 morphospecies, and 24–128 distinct arthropod families per house. The majority of this indoor diversity (73%) was made up of true flies (Diptera), spiders (Araneae), beetles (Coleoptera), and wasps and kin (Hymenoptera, especially ants: Formicidae). Much of the arthropod diversity within houses did not consist of synanthropic species, but instead included arthropods that were filtered from the surrounding landscape. As such, common pest species were found less frequently than benign species. Some of the most frequently found arthropods in houses, such as gall midges (Cecidomyiidae) and book lice (Liposcelididae), are unfamiliar to the general public despite their ubiquity. These findings present a new understanding of the diversity, prevalence, and distribution of the arthropods in our daily lives. Considering their impact as household pests, disease vectors, generators of allergens, and facilitators of the indoor microbiome, advancing our knowledge of the ecology and evolution of arthropods in homes has major economic and human health implications

    Damage Detection and Verification System (DDVS) for In-Situ Health Monitoring

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    Project presentation for Game Changing Program Smart Book Release. Detection and Verification System (DDVS) expands the Flat Surface Damage Detection System (FSDDS) sensory panels damage detection capabilities and includes an autonomous inspection capability utilizing cameras and dynamic computer vision algorithms to verify system health. Objectives of this formulation task are to establish the concept of operations, formulate the system requirements for a potential ISS flight experiment, and develop a preliminary design of an autonomous inspection capability system that will be demonstrated as a proof-of-concept ground based damage detection and inspection system

    A Missense Mutation in the Collagen Triple Helix of EDA Is Associated with X-Linked Recessive Hypohidrotic Ectodermal Dysplasia in Fleckvieh Cattle.

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    Mutations within the ectodysplasin A (EDA) gene have been associated with congenital hypotrichosis and anodontia (HAD/XHED) in humans, mice, dogs and cattle. We identified a three-generation family of Fleckvieh cattle with male calves exhibiting clinical and histopathological signs consistent with an X-linked recessive HAD (XHED). Whole genome and Sanger sequencing of cDNA showed a perfect association of the missense mutation g.85716041G>A (ss2019497443, rs1114816375) within the EDA gene with all three cases following an X-linked recessive inheritance, but normal EDAR and EDARADD. This mutation causes an exchange of glycine (G) with arginine (R) at amino acid position 227 (p.227G>R) in the second collagen triple helix repeat domain of EDA. The EDA variant was associated with a significant reduction and underdevelopment of hair follicles along with a reduced outgrowth of hairs, a complete loss of seromucous nasolabial and mucous tracheal and bronchial glands and a malformation of and reduction in number of teeth. Thermostability of EDA G227R was reduced, consistent with a relatively mild hair and tooth phenotype. However, incisors and canines were more severely affected in one of the calves, which correlated with the presence of a homozygous missense mutation of RNF111 (g.51306765T>G), a putative candidate gene possibly associated with tooth number in EDA-deficient Fleckvieh calves
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