Generation of three-dimensional body-fitted coordinates using hyperbolic partial differential equations

An efficient numerical mesh generation scheme capable of creating orthogonal or nearly orthogonal grids about moderately complex three dimensional configurations is described. The mesh is obtained by marching outward from a user specified grid on the body surface. Using spherical grid topology, grids have been generated about full span rectangular wings and a simplified space shuttle orbiter

Some Contributions to the Risk of the Nearest Neighbor Rulesv

Upper bounds are derived for the finite-sample risk Rm for distributions having unbounded support, for which we found upper bounds on the expected nearest neighbor distance. We look at real-valued observations and remarks on the multidimensional case. The upper bounds of some distributions are set as typical

Bounds on the finite-sample risk for exponential distribution.

In this paper, we derive lower and upper bounds on the expected nearest neighbor distance for exponential distribution, and find lower and upper bounds on the risk of the nearest neighbor of exponential distribution

Use of a hyperbolic grid generation scheme in simulating supersonic viscous flow about three-dimensional winged configuration

The present paper describes a numerical mesh generation technique to be used with an implicit finite difference method for simulating visous supersonic flow about low-aspect-ratio wing body configurations using a single grid strategy. The computational domain is segmented into multiple regions, with borders located in supersonic areas to avoid the otherwise costly interfacing procedure between adjacent segments. The numerical procedure is applied to calculate the turbulent flow around the shuttle orbiter and a canard projectile at supersonic free stream Mach number

Viscous computation of a space shuttle flow field

A procedure is presented, as well as some results, to calculate the flow over the winged orbiter. This necessitates the use of two computer codes. A parabolized marching Navier-Stokes code is used to obtain the solution up to the bow shock-wing shock interaction region and for the region after the interaction. An unsteady Navier-Stokes code is to be used in the region of the shock interaction. Only resuls for the marching code are presented. For the flow conditions calculated, M infinity = 7.9, alpha = 25 deg, T(wall) = 540 R, Re(L) = 60728 per inch, laminar or turbulent, the PNS code was marched up to an X/L = 0.7 which is where the bow shock-wing shock interaction region occurs

Aerodynamic effects of nearly uniform slipstreams on thin wings in the transonic regime

A simplified model is used to describe the interaction between a propeller slipstream and a wing in the transonic regime. The undisturbed slipstream boundary is assumed to coincide with an infinite circular cylinder. The undisturbed slipstream velocity is rotational and is a function of the radius only. In general, the velocity perturbation caused by introducing a wing into the slipstream is also rotational. By making small disturbance assumptions, however, the perturbation velocity becomes nearly potential, and an approximation for the flow is obtained by solving a potential equation

Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Recent multi-photon ionization (MPI) experiments on uracil revealed a fragment ion at m/z 84 that was proposed as a potential marker for ring opening in the electronically excited neutral molecule. The present MPI measurements on deuterated uracil identify the fragment as C3H4N2O+ (uracil+ less CO), a plausible dissociative ionization product from the theoretically predicted open-ring isomer. Equivalent measurements on thymine do not reveal an analogous CO loss channel, suggesting greater stability of the excited DNA base. MPI and electron impact ionization experiments have been carried out on uracil-adenine clusters in order to better understand the radiation response of uracil within RNA. Evidence for C3H4N2O+ production from multi-photon-ionized uracil-adenine clusters is tentatively attributed to a significant population of π-stacked configurations in the neutral beam

Association of lipid profile and waist circumference as cardiovascular risk factors for overweight and obesity among school children in Qatar

Background: Childhood obesity is a national as well as worldwide problem. The aim of this study was to evaluate the association of overweight and obesity among Qatari children with lipid profile and waist circumference as adverse cardiovascular risk factors in children aged 6-11 years. International Obesity Task Force reference values were used to screen for overweight and obesity. Methods: A cross-sectional study in a randomly selected sample was conducted in 315 Qatari primary school students aged 6-11 years. Anthropometric measurements, including body weight, height, waist circumference, and body mass index were calculated for 151 girls and 164 boys. Weight categories were based on International Obesity Task Force reference values. Fasting blood glucose, total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides were measured, and atherogenic index was calculated. Results: In total, 31.71% of boys and 32.78% of girls were overweight or obese. Overweight and obese children screened against International Obesity Task Force reference values had a significantly increased risk of high waist circumference (P < 0.0001), hypertriglyceridemia (P = 0.002), low HDL-C (P = 0.017), and atherogenic index (P = 0.021) compared with children who were not overweight or obese. The partial correlation coefficient for the cardiovascular risk marker of waist circumference indicated a positive significant association with total cholesterol (r = 0.465, P = 0.003), triglycerides (r = 0.563, P < 0.001), and LDL-C (r = 0.267, P = 0.003), and a significant negative association with HDL-C (r = -0.361, P = 0.004). Overweight and obesity significantly increase the odds ratios (ORs) and 95% confidence interval (CIs) of cardiovascular risk factors as follows: Hypertriglyceridemia (OR 6.34, CI 2.49-13.44, P < 0.0001); LDL-C (OR 3.18, CI 1.0419.75, P = 0.043); hypercholesterolemia (OR 1.88, CI 1.10-3.19, P = 0.020); and increased waist circumference (OR 1.40, CI 1.29-1.55, P = 0.022). Overweight and obesity significantly increased the risk of atherosclerosis (assessed by atherogenic index) by about two-fold (OR 1.83, 95% CI 1.06-3.15, P = 0.025). Conclusion: Overweight and obese children screened by International Obesity Task Force reference values are at increased risk of cardiovascular disease in adulthood

Numerical simulation of the flow about an F-18 aircraft in the high-alpha regime

The current research is aimed at developing and extending numerical methods to accurately predict the high Reynolds number flow about the NASA F-18 HARV at large angles of attack. The resulting codes are validated by comparison of the numerical results with in-flight aerodynamic measurements and flow visualization obtained on the HARV. Further, computations have been used to provide an analysis and numerical optimization of a pneumatic slot blowing concept, and a mechanical strake concept, for use as potential forebody flow control devices in improving high-alpha maneuverability