219 research outputs found

    Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

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    Equations and in computer code are presented for the thermodynamic and transport properties of gaseous, undissociated tetrafluoromethane (CF4) in chemical equilibrium. The computer code calculates the thermodynamic and transport properties of CF4 when given any two of five thermodynamic variables (entropy, temperature, volume, pressure, and enthalpy). Equilibrium thermodynamic and transport property data are tabulated and pressure-enthalpy diagrams are presented

    A simple integral method for the calculation of real-gas turbulent boundary layers with variable edge entropy

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    Simple integral method for calculating real gas turbulent boundary layers with variable edge entropy and flight calculations showing effect of nose bluntness at 6.09 km/se

    A method for calculating a real-gas two-dimensional nozzle contour including the effects of gamma

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    A method for calculating two-dimensional inviscid nozzle contours for a real gas or an ideal gas by the method of characteristics is described. The method consists of a modification of an existing nozzle computer program. The ideal-gas nozzle contour can be calculated for any constant value of gamma. Two methods of calculating the center-line boundary values of the Mach number in the throat region are also presented. The use of these three methods of calculating the center-line Mach number distribution in the throat region can change the distance from the throat to the inflection point by a factor of 2.5. A user's guide is presented for input to the computer program for both the two-dimensional and axisymmetric nozzle contours

    A vectorization of the Hess McDonnell Douglas potential flow program NUED for the STAR-100 computer

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    The computer program NUED for analyzing potential flow about arbitrary three dimensional lifting bodies using the panel method was modified to use vector operations and run on the STAR-100 computer. A high speed of computation and ability to approximate the body surface with a large number of panels are characteristics of NUEDV. The new program shows that vector operations can be readily implemented in programs of this type to increase the computational speed on the STAR-100 computer. The virtual memory architecture of the STAR-100 facilitates the use of large numbers of panels to approximate the body surface

    Computer program for calculation of real gas turbulent boundary layers with variable edge entropy

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    A user's manual for a computer program which calculates real gas turbulent boundary layers with variable edge entropy on a blunt cone or flat plate at zero angle of attack is presented. An integral method is used. The method includes the effect of real gas in thermodynamic equilibrium and variable edge entropy. A modified Crocco enthalpy velocity relationship is used for the enthalpy profiles and an empirical correlation of the N-power law profile is used for the velocity profile. The skin-friction-coefficient expressions of Spalding and Chi and Van Driest are used in the solution of the momentum equation and in the heat-transfer predictions that use several modified forms of Reynolds analogy

    Numerical and experimental studies of the natural convection within a horizontal cylinder

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    Numerical solutions are obtained for the quasi-compressible Navier-Stokes equations governing the time-dependent natural convection within a horizontal cylinder. The early flow development and wall heat transfer are obtained after a uniformly cold wall is imposed as a boundary condition on the cylinder. Results are also obtained for a time-varying cold wall as a boundary condition with windward explicit differencing used for the numerical solutions. The viscous truncation error associated with this scheme is controlled so that first-order accuracy is maintained in time and space. Experiments within a small-scale instrumented horizontal cylinder revealed the time development of the temperature distribution across the boundary layer as well as the decay of wall heat transfer with time. Agreement between temperature distributions obtained experimentally and numerically was generally good. The time decay of the dimensionless ratio of the Nusselt number to the one-fourth power of the Grashof number is found both numerically and experimentally, and good agreement is obtained between these two results over most of the cylinder wall

    Lifecourse Childhood Adiposity Trajectories Associated With Adolescent Insulin Resistance

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    OBJECTIVE In the light of the obesity epidemic, we aimed to characterize novel childhood adiposity trajectories from birth to age 14 years and to determine their relation to adolescent insulin resistance. RESEARCH DESIGN ANDMETHODS A total of 1,197 Australian children with cardiovascular/ metabolic proiling at age 14 years were studied serially from birth to age 14 years.Semiparametric mixture modeling was applied to anthropometric data over eight time points to generate adiposity trajectories of z scores (weight-for-height and BMI). Fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were compared at age 14 years between adiposity trajectories. RESULTS Seven adiposity trajectories were identified. Three (two rising and one chronic high adiposity) trajectories comprised 32% of the population and were associated with significantly higher fasting insulin and HOMA-IR compared with a reference trajectory group (with longitudinal adiposity z scores of approximately zero). There was a significant sex by trajectory group interaction (P,0.001). Girls within a rising trajectory fromlow tomoderate adiposity did not show increased insulin resistance. Maternal obesity, excessive weight gain during pregnancy,and gestational diabetes were more prevalent in the chronic high adiposity trajectory. CONCLUSIONS A range of childhood adiposity trajectories exist. The greatest insulin resistance at age 14 years is seen in those with increasing trajectories regardless of birth weight and in high birth weight infants whose adiposity remains high. Public health professionals should urgently target both excessive weight gain in early childhood across all birth weights and maternal obesity and excessive weight gain during pregnancy

    The Portuguese version of the Psychological Adjustment to Separation Test-Part A (PAST-A): a study with recently and non-recently divorced adults

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    Past research has demonstrated that divorced adults show more health problems and psychological distress than married adults. Considering the high prevalence rates of divorce among Western countries, new and robust measures should be developed to measure psychological distress after this specific transition in adulthood. The aim of this study was to adapt and validate a Portuguese version of the Psychological Adjustment to Separation Test-Part A (PAST-A; Sweeper and Halford in J Family Psychol 20(4):632–640, 2006). PAST-A is a self-report measure that assesses two key dimensions of separation adjustment problems: lonely-negativity and former partner attachment. Psychometric properties of the Portuguese version of PAST-A were assessed in terms of factor structure, internal consistency, and convergent and divergent validity, in an online convenience sample with divorced adults (N = 460). The PAST-A two-factor structure was confirmed by exploratory and confirmatory factor analyses, with each factor demonstrating very satisfactory internal consistency and good convergence. In terms of discriminant validity, the Portuguese PAST-A reveals a distinct factor from psychological growth after divorce. The results provided support for the use of the Portuguese PAST-A with divorced adults and also suggested that the explicative factors of the psychological adjustment to divorce may be cross-cultural stable. The non-existence of validated divorce-related well-being measures and its implications for divorce research are also discussed

    An exploration into the impact of exposure to community violence and hope on children's perceptions of well-being: a South African perspective

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    The study aims to explore the relationship between exposure to community violence, hope, and well-being. More specifically, the study aims to ascertain whether hope is a stronger predictor of well-being than exposure to violence. Stratified random sampling was used to select a sample of 566 adolescents aged 14–17 years, from both high violence and low violence areas in Cape Town, South Africa. A questionnaire consisting of Snyder’s Children’s Hope Scale, the Recent Exposure to Violence Scale and the KIDSCREEN-52 was used. Data analysis techniques included descriptive statistics, correlations, and multiple regression. A positive, significant relationship was found between children’s hope and their well-being. Although exposure to community violence was found to be significantly correlated with wellbeing, the relationship was negligible.While exposure to community violence and hope were found to be significant predictors of well-being, hope emerged as a stronger predictor of child well-being than exposure to community violence.Department of HE and Training approved lis
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