21,064 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
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 programmer's manual updates for aeroelastic analysis of bladed discs
The programming routines for the NASTRAN Level 16program are presented. Particular emphasis is placed on its application to aeroelastic analyses, mode development, and flutter analysis for turbomachine blades
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
Confined water in the low hydration regime
Molecular dynamics results on water confined in a silica pore in the low
hydration regime are presented. Strong layering effects are found due to the
hydrophilic character of the substrate. The local properties of water are
studied as function of both temperature and hydration level. The interaction of
the thin films of water with the silica atoms induces a strong distortion of
the hydrogen bond network. The residence time of the water molecules is
dependent on the distance from the surface. Its behavior shows a transition
from a brownian to a non-brownian regime approaching the substrate in agreement
with results found in studies of water at contact with globular proteins.Comment: 7 pages with 12 figures (RevTeX4). To be published on J. Chem. Phy
Letter to the editor: autoimmune pathogenic mechanisms in amyotrophic lateral sclerosis
The innate immune system may affect the function and survival of motor neurons in ALS by at least three mechanisms. First, there is evidence to suggest that aggregates of mutant SOD1—which is derived from microglial and astroglial cells—activate neighbouring microglia by binding to TLR2, TLR4, and CD14, and subsequently promote neuronal cell death [9]. Second, the release of pro- inflammatory cytokines may drive motor neuron damage. Third, although poorly understood, a mechanism has been suggested on the basis of the functional analysis of microglial cells that express mutant SOD1 [10]. These cells showed impaired overall motility and a reduced capacity to clear neuronal cell debris. Impairment of microglial cell phagocytosis may therefore contribute to the accumulation of further immunostimulatory proteins, including mutant SOD1, chromogranin A, and dsRNA, thereby resulting in disease progression
Random sequential adsorption and diffusion of dimers and k-mers on a square lattice
We have performed extensive simulations of random sequential adsorption and
diffusion of -mers, up to in two dimensions with particular attention
to the case . We focus on the behavior of the coverage and of vacancy
dynamics as a function of time. We observe that for a complete coverage
of the lattice is never reached, because of the existence of frozen
configurations that prevent isolated vacancies in the lattice to join. From
this result we argue that complete coverage is never attained for any value of
. The long time behavior of the coverage is not mean field and nonanalytic,
with as leading term. Long time coverage regimes are independent of
the initial conditions while strongly depend on the diffusion probability and
deposition rate and, in particular, different values of these parameters lead
to different final values of the coverage. The geometrical complexity of these
systems is also highlighted through an investigation of the vacancy population
dynamics.Comment: 9 pages, 9 figures, to be published in the Journal of Chemical
Physic
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