36,788 research outputs found
Year One portfolio of work
Brief 01-Walk the Line; Brief 02-The Nomad; Brief 03-The Fridge; Brief 04-The Solid Void; One Day Project 01-The Film; One Day Project 02-The Shadow; Brief 05-The Modern Living Project-Morphosis Exhibition; Brief 06-Beach Hut; Brief 07 CDP-The Gallery; Technology Assignment 01-Construction-Cobtun House; Technology Assignment 02-Environmental-Brooke Combes House
NASTRAN nonlinear vibration analysis of beam and frame structures
A capability for the nonlinear vibration analysis of beam and frame structures suitable for use with NASTRAN level 15.5 is described. The nonlinearity considered is due to the presence of axial loads induced by longitudinal end restraints and lateral displacements that are large compared to the beam height. A brief discussion is included of the mathematical analysis and the geometrical stiffness matrix for a prismatic beam (BAR) element. Also included are a brief discussion of the equivalent linearization iterative process used to determine the nonlinear frequency, the required modifications to subroutines DBAR and XMPLBD of the NASTRAN code, and the appropriate vibration capability, four example problems are presented. Comparisons with existing experimental and analytical results show that excellent accuracy is achieved with NASTRAN in all cases
The 30/20 GHZ net market assessment
By creating a number of market scenarios variations dealing with network types, network sizes, and service price levels were analyzed for their impact on market demand. Each market scenario represents a market demand forecast with results for voice, data, and video service traffic expressed in peak load megabits per second
No Generalized TMD-Factorization in the Hadro-Production of High Transverse Momentum Hadrons
It has by now been established that standard QCD factorization using
transverse momentum dependent parton distribution functions fails in
hadro-production of nearly back-to-back hadrons with high transverse momentum.
The essential problem is that gauge invariant transverse momentum dependent
parton distribution functions cannot be defined with process-independent Wilson
line operators, thus implying a breakdown of universality. This has led
naturally to proposals that a correct approach is to instead use a type of
"generalized" transverse momentum dependent factorization in which the basic
factorized structure is assumed to remain valid, but with transverse momentum
dependent parton distribution functions that contain non-standard, process
dependent Wilson line structures. In other words, to recover a factorization
formula, it has become common to assume that it is sufficient to simply modify
the Wilson lines in the parton correlation functions for each separate hadron.
In this paper, we will illustrate by direct counter-example that this is not
possible in a non-Abelian gauge theory. Since a proof of generalized transverse
momentum dependent factorization should apply generally to any hard
hadro-production process, a single counter-example suffices to show that a
general proof does not exist. Therefore, to make the counter-argument clear and
explicit, we illustrate with a specific calculation for a double spin asymmetry
in a spectator model with a non-Abelian gauge field. The observed breakdown of
generalized transverse momentum dependent factorization challenges the notion
that the role of parton transverse momentum in such processes can be described
using separate correlation functions for each external hadron.Comment: 19 pages, 11 figures, typos fixed and minor explanations added,
version to appear in Physical Review
Numerical Algorithm for Detecting Ion Diffusion Regions in the Geomagnetic Tail with Applications to MMS Tail Season May 1 -- September 30, 2017
We present a numerical algorithm aimed at identifying ion diffusion regions
(IDRs) in the geomagnetic tail, and test its applicability. We use 5 criteria
applied in three stages. (i) Correlated reversals (within 90 s) of Vx and Bz
(at least 2 nT about zero; GSM coordinates); (ii) Detection of Hall electric
and magnetic field signatures; and (iii) strong (>10 mV/m) electric fields.
While no criterion alone is necessary and sufficient, the approach does provide
a robust, if conservative, list of IDRs. We use data from the Magnetospheric
Multiscale Mission (MMS) spacecraft during a 5-month period (May 1 to September
30, 2017) of near-tail orbits during the declining phase of the solar cycle. We
find 148 events satisfying step 1, 37 satisfying steps 1 and 2, and 17
satisfying all three, of which 12 are confirmed as IDRs. All IDRs were within
the X-range [-24, -15] RE mainly on the dusk sector and the majority occurred
during traversals of a tailward-moving X-line. 11 of 12 IDRs were on the
dusk-side despite approximately equal residence time in both the pre- and
post-midnight sectors (56.5% dusk vs 43.5% dawn). MMS could identify signatures
of 4 quadrants of the Hall B-structure in 3 events and 3 quadrants in 7 of the
remaining 12 confirmed IDRs identified. The events we report commonly display
Vx reversals greater than 400 km/s in magnitude, normal magnetic field
reversals often >10 nT in magnitude, maximum DC |E| which are often well in
excess of the threshold for stage 3. Our results are then compared with the set
of IDRs identified by visual examination from Cluster in the years 2000-2005.Comment: In Submission at JGR:Space Physic
Stratospheric CCN sampling program
Two one liter grab samples of stratospheric aerosol were returned from each of six U-2 sampling missions. Cloud condensation nuclei (CCN) spectra from each sample were obtained. Interest was centered on the effects of volcanic activity. Spurious particle generation was found to be a serious problem in container 9 LFT and a much smaller problem in container 9 RT. Initial studies of an option for improved sample containers and values were completed. A CCN spectrometer, able to operate at an internal pressure of 300 mb, was designed
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