Computer program for solving laminar, transitional, or turbulent compressible boundary-layer equations for two-dimensional and axisymmetric flow

A numerical algorithm and computer program are presented for solving the laminar, transitional, or turbulent two dimensional or axisymmetric compressible boundary-layer equations for perfect-gas flows. The governing equations are solved by an iterative three-point implicit finite-difference procedure. The software, program VGBLP, is a modification of the approach presented in NASA TR R-368 and NASA TM X-2458, respectively. The major modifications are: (1) replacement of the fourth-order Runge-Kutta integration technique with a finite-difference procedure for numerically solving the equations required to initiate the parabolic marching procedure; (2) introduction of the Blottner variable-grid scheme; (3) implementation of an iteration scheme allowing the coupled system of equations to be converged to a specified accuracy level; and (4) inclusion of an iteration scheme for variable-entropy calculations. These modifications to the approach presented in NASA TR R-368 and NASA TM X-2458 yield a software package with high computational efficiency and flexibility. Turbulence-closure options include either two-layer eddy-viscosity or mixing-length models. Eddy conductivity is modeled as a function of eddy viscosity through a static turbulent Prandtl number formulation. Several options are provided for specifying the static turbulent Prandtl number. The transitional boundary layer is treated through a streamwise intermittency function which modifies the turbulence-closure model. This model is based on the probability distribution of turbulent spots and ranges from zero to unity for laminar and turbulent flow, respectively. Several test cases are presented as guides for potential users of the software

User's operating procedures. Volume 3: Projects directorate information programs

A review of the user's operating procedures for the scout project automatic data system, called SPADS is presented. SPADS is the results of the past seven years of software development on a prime mini-computer. SPADS was developed as a single entry, multiple cross-reference data management and information retrieval system for the automation of Project office tasks, including engineering, financial, managerial, and clerical support. This volume, three of three, provides the instructions to operate the projects directorate information programs in data retrieval and file maintenance via the user friendly menu drivers

Does relative deprivation induce migration?: evidence from Sub-Saharan Africa

This analysis revisits the decades-old relative deprivation theory of migration. In contrast to the traditional view that migration is driven by absolute income maximization, we test whether relative deprivation induces migration in the context of sub-Saharan Africa. Taking advantage of the internationally comparable longitudinal data from integrated household and agriculture surveys from Tanzania, Ethiopia, Malawi, Nigeria, and Uganda, we use panel fixed effects to estimate the effects of relative deprivation on migration decisions. Using per capita consumption expenditure and multidimensional wealth index as well-being measures, we find that a household’s migration decision is based not only on its absolute well-being level but also on the relative position of the household in the well-being distribution of the community in which it resides. We also discover that the effect of relative deprivation on migration is amplified in rural, agricultural, and male-headed households. Results are robust to alternative specifications including the use of Hausman Taylor Instrumental Variable (HTIV) estimator and pooled data across the five countries. Results confirm that the “migration-relative deprivation” relationship also holds in the context of sub-Saharan Africa. We argue that policies designed to check rural–urban migration through rural transformation and poverty reduction programs should use caution because such programs can increase economic inequality, which further increases migration flow

Tools made of ice facilitate forming of soft, sticky materials

Tools made of ice facilitate the forming or shaping of materials that are soft and sticky in the uncured state. The low-temperature of the ice slows the curing of the material, extending the working time available before setup. Handling problems are eliminated because the material does not adhere to the tool, and the melting ice serves as a lubricant

Measurement of the derivative 'ZW' for an oscillating aerofoil

This report presents the results of experimental measurements of the damping derivative coefficient zw for constant chord rigid wings of various aspect ratios having sweepback angles of zero and 450. The results for the rectangular wings Flow substantial agreement with the unsteady aerofoil theory developed by TI.P. Jones $2) The dependence of Zvi upon frequency parameter is as given by theory and is much less than for two dimensional flow, but the numerical results are approximately 10 per cent below the theoretical. This is attributed to the large trailing edge angle 22° of the N.A.C.A. 0020 section used for the model aerofoils. The effect of sweepback is to decrease the numerical value of z , but this effect is much less pronounced, for low than for high aspect ratios. For aspect ratios 5 and 3 the numerical value is greater than would be given by a factor of proportionality equal to the cosine of the angle of sweepback. The measurements were corrected for tunnel interference by a method based on the theoretical work of 7.P.Jones.(1

Deep ROSAT-HRI observations of the NGC 1399/NGC 1404 region: morphology and structure of the X-ray halo

We present the analysis of a deep (167 ks) ROSAT HRI observation of the cD galaxy NGC 1399 in the Fornax cluster. Using both HRI and, at larger radii, archival PSPC data, we find that the radial behavior of the X-ray surface brightness profile is not consistent with a simple Beta model and suggests instead three distinct components. We use a multi-component bidimensional model to study in detail these three components that we identify respectively with the cooling flow region, the galactic and the cluster halo. From these data we derive a binding mass distribution in agreement with that suggested by optical dynamical indicators, with an inner core dominated by luminous matter and an extended dark halo differently distributed on galactic and cluster scales. The HRI data and a preliminary analysis of Chandra public data, allow us to detect significant density fluctuations in the halo. We discuss possible non-equilibrium scenarios to explain the hot halo structure, including tidal interactions with neighboring galaxies, ram stripping from the intra-cluster medium and merging events. In the innermost region of NGC 1399, the comparison between the X-ray and radio emission suggests that the radio emitting plasma is displacing and producing shocks in the hot X-ray emitting gas. We found that the NGC 1404 halo is well represented by a single symmetric Beta model and follows the stellar light profile within the inner 8 kpc. The mass distribution is similar to the `central' component of the NGC 1399 halo. At larger radii ram pressure stripping from the intra-cluster medium produces strong asymmetries in the gas distribution. Finally we discuss the properties of the point source population finding evidence of correlation between the source excess and NGC 1399.Comment: 34 pages in aastex5.0 format, including 28 B&W and 4 color figures. Uses LaTex packages: subfigure, lscape and psfig. Accepted for publication in ApJ. High resolution version can be found at: http://www.na.astro.it/~paolillo/publications.htm

User's operating procedures. Volume 2: Scout project financial analysis program

A review is presented of the user's operating procedures for the Scout Project Automatic Data system, called SPADS. SPADS is the result of the past seven years of software development on a Prime mini-computer located at the Scout Project Office, NASA Langley Research Center, Hampton, Virginia. SPADS was developed as a single entry, multiple cross-reference data management and information retrieval system for the automation of Project office tasks, including engineering, financial, managerial, and clerical support. This volume, two (2) of three (3), provides the instructions to operate the Scout Project Financial Analysis program in data retrieval and file maintenance via the user friendly menu drivers

Understanding Floristic Diversity Though a Database of Greene County Specimens

We present a floristic list of Greene County, Arkansas, based on accessioned collections from the Arkansas State University Herbarium (STAR). Currently, there are 1569 specimens representing 540 taxa from Greene County in STAR. Using the USDA Plants Database, plant species were analyzed according to whether or not they are native to the state as well as whether or not they have been previously documented as species occurring in the county. Having analyzed all the Greene County collections from STAR, we found 225 previously undocumented species. The data suggest that most of the specimens in the STAR collection were found in wooded areas and/or near water. This may be a reflection of sampling bias as two of the primary collectors of these specimens were primarily interested in bog habitats. For this reason, the Greene County collections may not fully represent all habitats in the county, but it is likely that they are a good representation of the county’s seeps and bogs. The STAR Herbarium is emerging as a critical resource for understanding botanical diversity in the eastern counties of Arkansas, but it is clear that additional collections are necessary to fully represent all habitats in these areas