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

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

Microcontroller Implementation of Fuzzy Guidance

In the last few years microcontrollers found a big place in industrial applications. It had been used in many applications such as washing machines, textile machines and many other fields. Microchip PIC microcontrollers are one of the most used types of microcontroller. In this paper we consider a method which can be used to implement a fuzzy control system and the description of this implementation technique. The proposed method will be applied to implement the fuzzy guidance systems on a microchip PIC16F877A microcontroller system

Role assigning and taking in cloud computing

The widespread use of cloud computing (CC) has brought to the forefront information technology (IT) governance issues, rendering the lack of expertise in handling CC-based IT controls a major challenge for business enterprises and other societal organizations. In the cloud-computing context, this study identifies and ranks the determinants of role assigning and taking by IT people. The study’s integrative research links CC and IT governance to humane arrangements, as it validates and ranks role assigning and taking components through in-depth interviews with twelve IT decision-makers and forty-four Information Systems Audit and Control Association (ISACA) members, engaged as panelists in a Delphi technique implementation. The empirical results recognize skills and competencies as prioritized determinants of IT controls, while IT security, risk and compliance emerge as capabilities crucial to evaluate and manage CC service providers. Despite the study’s generalizability limitations, its findings highlight future research paths and provide practical guidelines toward the high technology of open-market IT self-governance. The latter entails the humane flows of collegial control and responsibility, as opposed to the inhumane flows of authority and power, under the sequestered technique of the bureaucratically-hierarchized IT hetero-governanc

Thin-film ZnO charge-trapping memory cell grown in a single ALD step

Cataloged from PDF version of article.A thin-film ZnO-based single-transistor memory cell with a gate stack deposited in a single atomic layer deposition step is demonstrated. Thin-film ZnO is used as channel material and charge-trapping layer for the first time. The extracted mobility and subthreshold slope of the thin-film device are 23 cm2/V · s and 720 mV/dec, respectively. The memory effect is verified by a 2.35-V hysteresis in the Idrain–Vgate curve. Physics-based TCAD simulations show very good agreement with the experimental results providing insight to the charge-trapping physics

Numerical simulation of particulateflow in spiral separators (15 % solids)

Spiral separator is a gravity concentration device. It wasinvented by Humphreys in 1941.It is firstly designed anddeveloped based on experience and through many testingof prototypes and modifications. The main objective of thepresent study is simulation of the particulate-flow of morerealistic solids concentration (15% solids by weight) in spiralseparator. The study is based on Eulerian approach and RING K-E turbulence modelin. The results focus on particulate-flow characteristics such as velocity, and distribution and concentration of particulates on the spiral trough.The predicted results are compared with the experimentalin case LD9 coal spiral. Comparisons between numericaland measured data show good agreement

Elevated serum leptin levels in patients with acute myocardial infarction; correlation with coronary angiographic and echocardiographic findings

BACKGROUND: To assess the relationship between serial serum leptin levels in patients with acute myocardial infarction (AMI) who received thrombolysis and the degree of coronary atherosclerosis, coronary reperfusion, echocardiographic findings, and clinical outcome. 51 consecutive patients presenting with AMI were studied. Clinical characteristics including age, sex, body mass index (BMI) and cardiovascular risk factors were recorded. Serial serum leptin levels at the time of admission and subsequently at 0, 6, 12, 24, 36, 60 hours afterwards were obtained. Coronary angiography was performed in 34 patients; the relation between serum leptin levels and evidence of coronary reperfusion as well as the extent of coronary atherosclerosis according to the coronary artery surgery study classification (CASS) were evaluated. Echocardiographic evaluation was performed in all patients. 36 matched patients were enrolled as control group who had serum leptin level 9.4 ± 6.5 ng/ml. RESULTS: The patients mean age was 50.5 ± 10.6 years. There were 47 males and 3 females. 37.1% were diabetics, 23.5% were hypertensive, 21.6% were dyslipidemic and 22.7% were obese (BMI ≥ 30). Leptin concentrations (ng/ml) increased and peaked at the 4th sample (36 hrs) after admission (mean ± SD) sample (1) =9.55 ± 7.4, sample (2) =12.9 ± 8.4, sample (3) =13.8 ± 10.4, sample (4) =18.9 ± 18.1, sample (5) =11.4 ± 6.5, sample (6) =10.8 ± 8.9 ng/ml. There was a significant correlation between serum leptin and BMI (r = 0.342; p = 0.03). Leptin levels correlated significantly to creatine kinase level on the second day (r = 0.43, p ≤ 0.01). Significant correlation of mean serum leptin with the ejection fraction (P < 0.05) was found. No difference in timing of peak serum leptin between patients who achieved coronary reperfusion vs. those who did not (p = 0.8). There was a trend for an increase in the mean serum leptin levels with increasing number of diseased vessels. There was no correlation between serum leptin levels and outcome neither during the hospitalization nor at 9 months follow up. CONCLUSION: Serum leptin levels increase after myocardial infarction. Serum leptin level may be a predictor of the left ventricular ejection fraction and the degree of atherosclerosis but not of coronary reperfusion