54,565 research outputs found
NASTRAN modeling and analysis of rigid and flexible walled acoustic cavities
The acoustic slot elements, CSLOTi, are applied to analyze two-dimensional enclosures with fixed or moving boundaries. The capability utilized to compute (a) the acoustic natural modes and frequencies of a rigid walled enclosure and (b) the sound pressure at any point inside an enclosure when the surrounding walls are forced to vibrate. Applications to an automobile passenger compartment illustrate the technique. The axisymmetric fluid elements, CFLUIDi, are used in conjunction with a suitable choice of symmetry planes and a model of the surrounding structure to approximate a two-dimensional enclosure with flexible walls. The enclosure walls are modeled using finite elements or structural modes. Illustrative examples include a comparison of rectangular cavity modes with those calculated using the acoustic slot element and the free vibration modes of two enclosures coupled through a flexible rectangular panel
A Survey of Reproductive Management Strategies on US Commercial Dairy Farms
Reproductive performance on the dairy farm affects the dairy’s profit because it directly affects milk production, the availability of replacements, the amounts of voluntary and involuntary culling, breeding costs, and costs associated with veterinary care (Britt, 1985). Reproductive management programs selected for implementation differ across farms due to varying on-farm costs, such as labor costs, opportunity costs of management and labor, as well as facilities, farm goals and values, and management styles. The objective of this paper is to summarize survey data in order to aid in providing economic insight into why varying types of farms utilize different methods of reproductive management and differing reproductive technologies.
Growth Stimulation of Biological Cells and Tissue by Electromagnetic Fields and Uses Thereof
The present invention provides systems for growing two or three dimensional mammalian cells within a culture medium facilitated by an electromagnetic field, and preferably, a time varying electromagnetic field. The cells, and culture medium are contained within a fixed or rotating culture vessel, and the electromagnetic field is emitted from at least one electrode. In one embodiment, the electrode is spaced from the vessel. The invention further provides methods to promote neural tissue regeneration by means of culturing the neural cells in the claimed system. In one embodiment, neuronal cells are grown within longitudinally extending tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time varying electrical current is conducted, the conductive channels being positioned within a culture medium
Aligning Incentives for Contract Dairy Heifer Growth
As dairy farms grow and specialize in milking cows, raising replacement heifers is increasingly outsourced. Perhaps the largest challenge of outsourcing the heifer enterprise involves quality, measured as milk production potential, and the possibility for moral hazard due to hidden action on the part of the custom heifer grower. A principal-agent framework was used to elicit contract terms to provide incentives for the heifer grower to achieve desired growth rates, and enable the return of the heifer to the dairy farm on an accelerated time frame, without sacrificing quality. To mitigate incentive asymmetries, bonuses and deductions are proposed.contracts, heifer growth, moral hazard, principal agent, Livestock Production/Industries,
Role of spatial coherence in polarization tomography
We analyze an experimental setup in which a quasi-monochromatic spatially
coherent beam of light is used to probe a paraxial optical scatterer. We
discuss the effect of the spatial coherence of the probe beam on the Mueller
matrix representing the scatterer. We show that according to the degree of
spatial coherence of the beam, the \emph{same} scattering system can be
represented by \emph{different} Mueller matrices. This result should serve as a
warning for experimentalists.Comment: 3 pages, 1 figur
Investigation of line-of-sight propagation in dense atmosphere, phase 2 Final report, Jun. 1970 - Feb. 1971
Effect of microwave absorption and decimetric radio noise in Jovian atmospheres on radio communication in 1 to 10 GHz frequency ban
Black holes, parallelizable horizons and half-BPS states for the Einstein-Gauss-Bonnet theory in five dimensions
Exact vacuum solutions with a nontrivial torsion for the
Einstein-Gauss-Bonnet theory in five dimensions are constructed. We consider a
class of static metrics whose spacelike section is a warped product of the real
line with a nontrivial base manifold endowed with a fully antisymmetric
torsion. It is shown requiring solutions of this sort to exist, fixes the
Gauss-Bonnet coupling such that the Lagrangian can be written as a Chern-Simons
form. The metric describes black holes with an arbitrary, but fixed, base
manifold. It is shown that requiring its ground state to possess unbroken
supersymmetries, fixes the base manifold to be locally a parallelized
three-sphere. The ground state turns out to be half-BPS, which could not be
achieved in the absence of torsion in vacuum. The Killing spinors are
explicitly found.Comment: 11 pages, no figures, notation clarified; version accepted for
publication in Physical Review
Investigation of the anisotropy of dissipation processes in single crystal of Yba2Cu3O7-d system
By means of contactless mechanical method of the measurement of energy losses
in superconductors, the anisotropy of dissipation processes has been studied in
single crystal high-temperature layered superconductors of Yba2Cu3O7-d system,
being in mixed state. The observed anisotropy of energy losses indicates the
possibility of the existence of the symmetry of order parameter of dx2-y2 type
in these single crystals.Comment: 4 pages, 3 figure
- …