18,664 research outputs found
DESAP 1: A structural design program with stress and displacement constraints. Volume 1: Theoretical and user's manual
A finite element program is presented for computer-automated, minimum weight design of elastic structures with constraints on stresses (including local instability criteria) and displacements. Volume 1 of the report contains the theoretical and user's manual of the program. Sample problems and the listing of the program are included in Volumes 2 and 3. The element subroutines are organized so as to facilitate additions and changes by the user. As a result, a relatively minor programming effort would be required to make DESAP 1 into a special purpose program to handle the user's specific design requirements and failure criteria
DESAP 1: A structural design program with stress and displacement constraints. Volume 2: Sample problems
For abstract, see N77-18469
DESAP 2: A structural design program with stress and buckling constraints. Volume 1: Theoretical and user's manual
DESAP 2 is described as a finite element program for computer-automated, minimum weight design of elastic structures with constraints on stresses (including local instability criteria) and buckling loads. No limits are placed on the number of load conditions for stress-constrained design, but only one of these load conditions can be chosen as the potential buckling load. A substantial portion of DESAP 2, particularly the analysis of the prebuckling state, is derived from the SOLID SAP finite element program. The stress-constrained design is based on the classical stress ratio method, which drives the design towards a fully stressed state. The constraints on the buckling load are handled by solving the appropriate optimality criterion by successive iterations. During each iteration, the element sizes determined by the stress ratio method are used as the minimum size constraints. The element subroutines are organized in a manner that permits the user to make additions and changes with a minimal programming effort. Consequently, DESAP 2 can readily be changed into a special-purpose program to handle the user's specific design requirements and failure criteria
DESAP 2: A structural design program with stress and buckling constraints. Volume 3: Program listing
For abstract, see N77-18472
DESAP 2: A structural design program with stress and buckling constraints. Volume 2: Sample problems
For abstract, see N77-18472
The Stability of Non Newtonian Fluid Between the Two Rotating Porous Cylinders (Wide Gap Case)
This paper is primarily concerned with the stability of the non Newtonian fluid between two porous cylinders in the case of wide gap. The problem is discussed for Mhu>0,Mhu=0 and Mhu,0. The results show that the Taylor number depends on the gap size in the case of non Newtonian fluids and the presence of suction stabilizes the flow whereas the injection destabilizes the flow. Its is found the stability of the fluid decreases when the gap increases. The non Newtonian fluid is less stable when compared to the Newtonian fluid in the case of wide gap. It is also found in the case of wide gap(for non Newtonian fluid and the cylinders are counter rotating equally) the application of injection at the outer cylinder disturbs the radial velocity will not effect any appreciable change or disturbance in the vortex cell pattern at the onset of instability
Stability of a Non Newtonian Fluid Between Two Concentric Rotating Porous Cylinders
The stability of non-Newtonian fluid confined between two concentric rotating porous cylinders has been examined. The critical determines the on set of instability has been determined as a function of 'a' (wave length) and S (cross viscous parameter). The variation of the critical Taylor number with S, suction parameter lambda and radial velocity distribution have been shown. It has been found that the effect of suction at the outer cylinder is to stabilize the flow whereas the injection destabilizes the flow. The presence of suction or injection does not affect radial velocity curves or vortex cells
Photon temporal modes: a complete framework for quantum information science
Field-orthogonal temporal modes of photonic quantum states provide a new
framework for quantum information science (QIS). They intrinsically span a
high-dimensional Hilbert space and lend themselves to integration into existing
single-mode fiber communication networks. We show that the three main
requirements to construct a valid framework for QIS -- the controlled
generation of resource states, the targeted and highly efficient manipulation
of temporal modes and their efficient detection -- can be fulfilled with
current technology. We suggest implementations of diverse QIS applications
based on this complete set of building blocks.Comment: 17 pages, 13 figure
Far-infrared study of K giants in the solar neighborhood: Connection between Li enrichment and mass-loss
We searched for a correlation between the two anomalous properties of K
giants: Li enhancement and IR excess from an unbiased survey of a large sample
of RGB stars. A sample of 2000 low-mass K giants with accurate astrometry from
the Hipparcos catalog was chosen for which Li abundances have been determined
from low-resolution spectra. Far-infrared data were collected from the
and catalogs. To probe the correlation between the two anomalies, we
supplemented 15 Li-rich K giants discovered from this sample with 25 known
Li-rich K giants from other studies. Dust shell evolutionary models and
spectral energy distributions were constructed using the code DUSTY to estimate
different dust shell properties, such as dust evolutionary time scales, dust
temperatures, and mass-loss rates. Among 2000 K giants, we found about two
dozen K giants with detectable far-IR excess, and surprisingly, none of them
are Li-rich. Similarly, the 15 new Li-rich K giants that were identified from
the same sample show no evidence of IR excess. Of the total 40 Li-rich K
giants, only 7 show IR excess. Important is that K giants with Li enhancement
and/or IR excess begin to appear only at the bump on the RGB. Results show that
K giants with IR excess are very rare, similar to K giants with Li enhancement.
This may be due to the rapid differential evolution of dust shell and Li
depletion compared to RGB evolutionary time scales. We also infer from the
results that during the bump evolution, giants probably undergo some internal
changes, which are perhaps the cause of mass-loss and Li-enhancement events.
However, the available observational results do not ascertain that these
properties are correlated. That a few Li-rich giants have IR excess seems to be
pure coincidence.Comment: Accepted for Publication in Astronomy & Astrophysics, 6 figures, 5
tables, 19 page
The Arabidopsis JAGGED gene encodes a zinc finger protein that promotes leaf tissue development
Important goals in understanding leaf development are to identify genes involved in pattern specification, and also genes that translate this information into cell types and tissue structure. Loss-of-function mutations at the JAGGED (JAG) locus result in Arabidopsis plants with abnormally shaped lateral organs including serrated leaves, narrow floral organs, and petals that contain fewer but more elongate cells. jag mutations also suppress bract formation in leafy, apetala1 and apetala2 mutant backgrounds. The JAG gene was identified by map-based cloning to be a member of the zinc finger family of plant transcription factors and encodes a protein similar in structure to SUPERMAN with a single C2H2-type zinc finger, a proline-rich motif and a short leucine-rich repressor motif. JAG mRNA is localized to lateral organ primordia throughout the plant but is not found in the shoot apical meristem. Misexpression of JAG results in leaf fusion and the development of ectopic leaf-like outgrowth from both vegetative and floral tissues. Thus, JAG is necessary for proper lateral organ shape and is sufficient to induce the proliferation of lateral organ tissue
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