15,301 research outputs found
Four New Capabilities in NASTRAN for Dynamic and Aeroelastic Analyses of Rotating Cyclic Structures
Static aerothermoelastic design/analysis of axial-flow compressors, modal flutter analysis of axial-flow turbomachines, forced vibration analysis of rotating cyclic structures and modal flutter analysis of advanced turbopropellers with highly swept blades are four new capabilities developed and implemented in NASTRAN Level 17.7. The contents, applicability and usefulness of these capabilities which were developed and documented under the sponsorship of NASA's Lewis Research Center are discussed. Overall flowcharts and selected examples are presented
Skin microbiota: a source of disease or defence?
Microbes found on the skin are usually regarded as pathogens, potential pathogens or innocuous symbiotic organisms. Advances in microbiology and immunology are revising our understanding of the molecular mechanisms of microbial virulence and the specific events involved in the host-microbe interaction. Current data contradict some historical classifications of cutaneous microbiota and suggest that these organisms may protect the host, defining them not as simple symbiotic microbes but rather as mutualistic. This review will summarize current information on bacterial skin flora including Staphylococcus, Corynebacterium, Propionibacterium, Streptococcus and Pseudomonas. Specifically, the review will discuss our current understanding of the cutaneous microbiota as well as shifting paradigms in the interpretation of the roles microbes play in skin health and disease
NASTRAN level 16 user's manual updates for aeroelastic analysis of bladed discs
The NASTRAN aeroelastic and flutter capability was extended to solve a class of problems associated with axial flow turbomachines. The capabilities of the program are briefly discussed. The aerodynamic data pertaining to the bladed disc sector, the associated aerodynamic modeling, the steady aerothermoelastic 'design/analysis' formulations, and the modal, flutter, and subcritical roots analyses are described. Sample problems and their solutions are included
NASTRAN level 16 demonstration manual updates for aeroelastic analysis of bladed discs
A computer program based on state of the art compressor and structural technologies applied to bladed shrouded discs was developed and made operational in NASTRAN level 16. The problems encompassed include aeroelastic analyses, modes, and flutter. The demonstration manual updates are described
Computer simulation of the phase diagram for a fluid confined in a fractal and disordered porous material
We present a grand canonical Monte Carlo simulation study of the phase
diagram of a Lennard-Jones fluid adsorbed in a fractal and highly porous
aerogel. The gel environment is generated from an off-lattice diffusion limited
cluster-cluster aggregation process. Simulations have been performed with the
multicanonical ensemble sampling technique. The biased sampling function has
been obtained by histogram reweighting calculations. Comparing the confined and
the bulk system liquid-vapor coexistence curves we observe a decrease of both
the critical temperature and density in qualitative agreement with experiments
and other Monte Carlo studies on Lennard-Jones fluids confined in random
matrices of spheres. At variance with these numerical studies we do not observe
upon confinement a peak on the liquid side of the coexistence curve associated
with a liquid-liquid phase coexistence. In our case only a shouldering of the
coexistence curve appears upon confinement. This shoulder can be associated
with high density fluctuations in the liquid phase. The coexisting vapor and
liquid phases in our system show a high degree of spatial disorder and
inhomogeneity.Comment: 8 pages, 8 figures, to be published in Phys. Rev.
Diffractive Interactions
The general framework of diffractive deep inelastic scattering is introduced
and reports given in the session on diffractive interactions at the
International Workshop on Deep-Inelastic Scattering and Related Phenomena,
Rome, April 1996, are presented.Comment: LaTeX with procl.sty, 20 pages. To appear in the Proceedings of the
International Workshop on Deep Inelastic Scattering and Related Phenomena,
Roma, Italy, April 199
Hodge polynomials of the moduli spaces of pairs
Let be a smooth projective curve of genus over the complex
numbers. A holomorphic pair on is a couple , where is a
holomorphic bundle over of rank and degree , and is
a holomorphic section. In this paper, we determine the Hodge polynomials of the
moduli spaces of rank 2 pairs, using the theory of mixed Hodge structures. We
also deal with the case in which has fixed determinant.Comment: 23 pages, typos added, minor change
An alternative method of analysis for base accelerated dynamic response in NASTRAN
An alternative method of analysis to determine the dynamic response of structures subjected to base accelerations is presented. The method is exact as opposed to the approximate technique of using unusually large masses and loads to enforce desired base accelerations. This paper presents the relevant equations to motion, ALTERs for direct and modal frequency-, random- and transient-response rigid formats, and illustrative examples
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