6,482 research outputs found
On inhibiting runaway in catalytic reactors
We consider the problem of heat and mass transfer in porous catalyst pellets. Both the steady and time dependent operating characteristics are studied. Accurate approximate equations are derived from the basic governing equations of motion. A nonlinear stability analysis is employed to account for the observation that under certain conditions reactions on catalyst pellets can pass transiently stably into a region which would correspond to instability in the steady state. One consequence of our analysis is a possible control mechanism which inhibits temperature runaway by extending the stable operating characteristics desirable in modern reactors
Results on improved KS dynamical configurations: spectrum, decay constants, etc
The MILC Collaboration has been producing ensembles of lattice configurations
with three dynamical flavors for the past few years. There are now results for
three lattice spacings for a variety of light and strange quark masses, ranging
down to , where is the dynamical strange quark mass and
is the common mass of the and quarks. Recently, the Fermilab,
HPQCD, MILC and UKQCD collaborations have presented a summary of results
obtained using these lattices. Compared with quenched results, these new
calculations show great improvement in agreement with experiment. This talk
addresses the technical improvements that make these calculations possible and
provides additional details of calculations not presented in the initial
summary. We demonstrate that a wide range of hadronic observables can now be
calculated to 2--3% accuracy.Comment: 10 pages, 17 figures (16 in color), Lattice2003(plenary), Plenary
talk presented at Lattice 2003, Tsukuba, Japan, July 15-19. Also presented at
Lattice Hadron Physics workshop, Cairns, Australia, July 22-30, 200
A linear polymer x-ray scattering model
In the development of X-ray scattering intensity curves physical models are necessary for the theoretical mathematical development involved. The purpose of this paper is the development of a physical model suitable for X-ray diffraction analysis or a linear polymer.
X-ray intensity patterns may be used to give a greater insight as to the atomic structure, configuration or atoms, molecular weight, and therefore a greater knowledge of the structure of matter, both microscopic and macroscopic. The converse may sometimes be used. An atom or molecular model is constructed, from this model X-ray scattering curves may be derived. These curves may be compared with known physical curves and if correct give us a greater insight into the mechanics or the interaction of matter.
The success or failure of the model depends on the details involved in constructing the model. The model should have characteristics that represent the outstanding property of the real material. If potential energy is assumed to of prime importance, then the model should be constructed so that potential energy is the predominate parameter in describing the system.
The following model takes the chemical-structure unit of the polymer as a unit or cell, and assumes the displacements of the cells are small enough such that the force between two adjacent structural-units is proportional to their separation distance --Introduction, page 1
RESORT + Additional Items
The recorded portion of my senior project consists of an album titled Resort, as well as additional pieces of music and visual art. The album is vaguely narrative driven, exploring parent-child relationships during climate catastrophe, and the decay of the mind’s ability to process these apocalyptic events. Intentionally throughout this project, climate change and its effects are blatantly aestheticized and romanticized to create a sinister-optimistic dreamlike album. I began this project with a phrase that wouldn’t leave my head: With rising seas, the whole world\u27s Resort. The concept of Resort is one that comes from a fixation on the aesthetics of climate change. The hedonism of late capitalism, and with it pervasive hyperreality, is situated to oppose the reality of its deterioration, creating a unique media language.
The album consists of ten main songs in a rough sequence. Throughout the production process, I heavily utilized simple, free MIDI plugins, to convey simplicity and timelessness without relying on conventional methods of aural deterioration/distortion such as simulated tape warble or bitcrushing. I also employed ethical sampling techniques, mainly consisting of the resampling of self-created audio.
I relied upon many free or pirated mastering programs/plugins; I wanted to seek the distortion that comes from misuse of tools meant to make music sound more professional. All of the visual components of this project were created with a similar ethos. I used tools such as letsenhance.io, a website which used neural networks to enhance low-resolution images. I found that through multiple uses of this tool on images which I curated and reduced in quality, a dreamlike, painterly effect came through.
The links to the audio files, which are hosted on Bandcamp, are included in my artist\u27s statement document.
Senior Project submitted to The Division of Arts of Bard College
I’ve Always Been A Rambler: An Exploration of Authenticity in Contemporary Folk Music
Senior Project submitted to The Division of Arts of Bard College
NASA supporting studies for microgravity research on eye movements
The purpose of the work on this project was to provide support for ground-based studies on the effects of gravity on eye movements. The effects of microgravity on the optokinetic eye movements of humans are investigated. OKN was induced by having subjects watch 3.3 deg stripes moving at 35 deg/s for 45 s in a binocular, head-fixed apparatus. The field (hor., 88 deg; vert., 72 deg), was rotated about axes that were upright or tilted 45 deg or 90 deg. The head was upright or tilted 45 deg on the body. Head-horizontal (yaw axis) and head-vertical (pitch axis) components of OKN were recorded with electro-oculography (EOG). Slow phase velocity vectors were determined relative to gravity. With the head upright, the axis of eye rotation during yaw axis OKN was coincident with the stimulus axis and the spatial vertical. With the head tilted 45 deg on the body, a persistent vertical component of eye velocity developed during yaw axis stimulation, and there was an average shift of the axis of eye rotation toward the spatial vertical of approximately 18 deg in six subjects. During oblique optokinetic stimulation with the head upright, the axis of eye rotation shifted 12 deg toward the spatial vertical. When the head was tilted, the axis of eye rotation rotated to the other side of the spatial vertical by 5.4 deg during the same oblique stimulation. This counter-rotation of the axis of eye rotation is similar to the 'Muller (E) effect', in which the perception of the upright counter-rotates to the opposite side of the spatial vertical when subjects are tilted in darkness. The data were simulated by a model of OKN. Despite the short OKAN time constants, strong horizontal to vertical cross-coupling was produced if the horizontal and vertical time constants were in proper ratio, and there was no suppression of nystagmus orthogonal to the stimulus direction. This shows that the spatial orientation of OKN can be due to a restructuring of the system matrix of velocity storage as a function of gravity. It is concluded that although human OKAN is weak, velocity storage orients the slow phase velocity of OKN towards the spatial vertical
Eulerian Statistically Preserved Structures in Passive Scalar Advection
We analyze numerically the time-dependent linear operators that govern the
dynamics of Eulerian correlation functions of a decaying passive scalar
advected by a stationary, forced 2-dimensional Navier-Stokes turbulence. We
show how to naturally discuss the dynamics in terms of effective compact
operators that display Eulerian Statistically Preserved Structures which
determine the anomalous scaling of the correlation functions. In passing we
point out a bonus of the present approach, in providing analytic predictions
for the time-dependent correlation functions in decaying turbulent transport.Comment: 10 pages, 10 figures. Submitted to Phys. Rev.
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