Numerical generation of two-dimensional grids by the use of Poisson equations with grid control at boundaries

A method for generating boundary-fitted, curvilinear, two dimensional grids by the use of the Poisson equations is presented. Grids of C-type and O-type were made about airfoils and other shapes, with circular, rectangular, cascade-type, and other outer boundary shapes. Both viscous and inviscid spacings were used. In all cases, two important types of grid control can be exercised at both inner and outer boundaries. First is arbitrary control of the distances between the boundaries and the adjacent lines of the same coordinate family, i.e., stand-off distances. Second is arbitrary control of the angles with which lines of the opposite coordinate family intersect the boundaries. Thus, both grid cell size (or aspect ratio) and grid cell skewness are controlled at boundaries. Reasonable cell size and shape are ensured even in cases wherein extreme boundary shapes would tend to cause skewness or poorly controlled grid spacing. An inherent feature of the Poisson equations is that lines in the interior of the grid smoothly connect the boundary points (the grid mapping functions are second order differentiable)

Simplified clustering of nonorthogonal grids generated by elliptic partial differential equations

A simple clustering transformation is combined with the Thompson, Thames, and Mastin (TTM) method of generating computational grids to produce controlled mesh spacings. For various practical grids, the resulting hybrid scheme is easier to apply than the inhomogeneous clustering terms included in the TTM method for this purpose. The technique is illustrated in application to airfoil problems, and listings of a FORTRAN computer code for this usage are included

Buoyant Venus station feasibility study. Volume IV - Communications and power Final report

Telecommunication and power supply requirements for inflatable buoyant Venus statio

Mirid-Bug Injury as a Factor in Declining Alfalfa-Seed Yields

During the forty or more millions of years that insects have inhabited the earth they have developed remarkable adaptations and great powers of reproduction that have enabled them to spread over most of the world and occupy all of its habitable environments. In cultivating the land and in growing crops, man has disturbed the balance in nature which formerly prevailed. By doing this he has unwittingly assisted many insect species to multiply in unprecedented numbers by providing them with more delectable food in abundance and by transporting them from place to place and from continent to continent in his migrations and commerce. Several species of insects, previously harmless, have become destructive pests of farm crops. It is highly probable that human activities have been largely responsible for local outbreaks of new insect pests which have attacked various crops with serious consequences. All insect species are not detrimental to human interests. Bees and other pollinizing insects are essential to profitable crops of certain fruits and agricultural seeds. The silkworm, honeybee, and lac insect produce silk, honey, beeswax, and shellac, the value of which aggregates hundreds of millions of dollars annually. Acknowledgements: The writer expresses his gratitude to the Faculty Association for the opportunity of presenting this treatise to its membership. Acknowledgement is made of the kind consideration of Director R. H. Walker, Utah Agricultural Experiment Station, who approved the use of the research data contained herein for this additional purpose. Thanks is also expressed to the Faculty Research Committee for suggestions given in connection with preparation of the manuscript. Valuable assistance rendered in the original research work by the following former students is greatfully acknowledged: Dr. L. Floyd Clark, Dr. Ray L. Janes, Lowell Cutler, and Farrell H. Gunnel

Circular No. 98 - Insects in Relation to Alfalfa-Seed Production

Various insect pests have been suspected of causing the unsatisfactory alfalfa-seed yields that have been obtained in Utah during recent years. No specific information was at hand giving the amount and nature of the damage which these insects were suspected of doing

Estimating Bank Lending Risk and Its Effect on Asset Allocation

The amount of risk that banks assume in lending is a key consideration in the amount of lending that banks ultimately will do. The relationship between default risk and lending levels is addressed here by deriving risk measures based on local economic industry mixes and locational characteristics of bank groups and then testing the degree to which differences in risk in local lending markets affect the asset allocation decisions of banks. FDIC call report data for West Virginia banks are combined with quarterly sectoral failure rate data and earnings data by sectors for the analysis

Development and flight tests of a Kalman filter for navigation during terminal area and landing operations

A Kalman filter for aircraft terminal area and landing navigation was implemented and flight tested in the NASA Ames STOLAND avionics computer onboard a Twin Otter aircraft. This system combines navaid measurements from TACAN, MODILS, air data, radar altimeter sensors along with measurements from strap-down accelerometer and attitude angle sensors. The flight test results demonstrate that the Kalman filter provides improved estimates of the aircraft position and velocity as compared with estimates from the more standard complementary filter. The onboard computer implementation requirements to achieve this improved performance are discussed

An examination of recent migration to Arizona: Working paper series--10-13

In the decades leading up to the current recession Arizona's population growth was among the fastest in the nation, with net domestic inmigration a major source of growth. In this paper we use Internal Revenue Service county migration data to examine migration flows to Arizona between 2006 and 2007. We examine both inmigration and net migration for Arizona counties and focus on the attraction of Arizona to outmigrants from other counties in the United States as well as from other states as a whole. We also examine migration flows with respect to distance from Arizona and location-specific factors in the origin and destination counties that impact migration decisions. Our findings revealed interesting differences among Arizona's counties in terms of overall net migration and origin states. While distance effects were significant, maps of the residuals from the regression models revealed regional clusters that indicate other factors also affect migration to Arizona. Comparisons of migration flows using the Rural-Urban Continuum Codes to classify origin and destination levels of urbanization reveal a tendency to move down the urban hierarchy when migrating to Arizona

Modular exponentiation via the explicit Chinese remainder theorem

In this paper we consider the problem of computing xe mod m for large integers x, e, and m. This is the bottleneck in Rabin’s algorithm for testing primality, the Diffie-Hellman algorithm for exchanging cryptographic keys, and many other common algorithms