19,163 research outputs found
Reprogramming the hand: bridging the craft skills gap in 3D/digital fashion knitwear design
Designer-makers have integrated a wide range of digital media and tools into their practices, many taking ownership of a specific technology or application and learning how to use it for themselves, often drawing on their experiential knowledge of established practices to do so. To date, there has been little discussion on how digital knitting practice has evolved within this context, possibly due to the complexity of the software, limited access to industrial machinery and the fact that it seems divorced from the idea of 'craft'. Despite the machine manufacturers' efforts to make knitting technology and software more user-friendly, the digital interface remains a significant barrier to knitwear designer-makers, generally only accessed via experienced technicians
Use of interactive graphics to analyze QUICK-geometry: Supplement
The advantages of using interactive computer graphics to display aircraft geometry to aid in detection and analysis of errors are described. The QUICK geometry system is reviewed and the Quick Interactive Graphics Analysis (QUIAGA) program is described. This QUIAGA program was developed to exercise the QUICK geometry subroutines to examine in several modes on a graphics terminal. Its use in the detection and analysis of errors in the QUICK geometry definition can be of great assistance in speedily arriving at a correct analytical geometry description for flow field computation. Experience with the program in developing a QUICK geometry model of the NASA Space Shuttle Orbiter is used to show some of its features. Appendixes giving details of program usage and an example session are included
The role of finite-difference methods in design and analysis for supersonic cruise
Finite-difference methods for analysis of steady, inviscid supersonic flows are described, and their present state of development is assessed with particular attention to their applicability to vehicles designed for efficient cruise flight. Current work is described which will allow greater geometric latitude, improve treatment of embedded shock waves, and relax the requirement that the axial velocity must be supersonic
Hypersonic aerodynamic characteristics of a family of power-law, wing body configurations
The configurations analyzed are half-axisymmetric, power-law bodies surmounted by thin, flat wings. The wing planform matches the body shock-wave shape. Analytic solutions of the hypersonic small disturbance equations form a basis for calculating the longitudinal aerodynamic characteristics. Boundary-layer displacement effects on the body and the wing upper surface are approximated. Skin friction is estimated by using compressible, laminar boundary-layer solutions. Good agreement was obtained with available experimental data for which the basic theoretical assumptions were satisfied. The method is used to estimate the effects of power-law, fineness ratio, and Mach number variations at full-scale conditions. The computer program is included
Axion-Dilaton Domain Walls and Fake Supergravity
Dynamical systems methods are used to investigate domain-wall solutions of a
two-parameter family of models in which gravity is coupled to an axion, and to
a dilaton with an exponential potential of either sign. A complete global
analysis is presented for (i) constant axion and (ii) flat walls, including a
study of bifurcations and a new exact domain-wall solution with non-constant
axion. We reconsider `fake supergravity' issues in light of these results. We
show, by example, how domain walls determine multi-valued superpotentials that
branch at stationary points that are not stationary points of the potential,
and we apply this result to potentials with anti-de Sitter vacua. We also show
by example that `adapted' truncation to a single-scalar model is sometimes
inconsistent, and we propose a `generalized' fake supergravity formalism that
applies in some such cases.Comment: 43pp, 19 figures; minor corrections and extensions; one additional
figur
A Note On Zeroes Of Superpotentials In F-Theory
We discuss the dependence of superpotential terms in 4D F-theory on moduli
parameters. Two cases are studied: the dependence on world-filling 3-brane
positions and the dependence on 2-form VEVs. In the first case there is a zero
when the 3-brane hits the divisor responsible for the superpotential. In the
second case, which has been extensively discussed by Witten in 3D M-theory,
there is a zero for special values of 2-form VEVs when the M-theory divisor
contains non-trivial 3-cycles. We give an alternative derivation of this fact
for the special case of F-theory.Comment: 12pp Te
Excitation of g modes in Wolf-Rayet stars by a deep opacity bump
We examine the stability of l=1 and l=2 g modes in a pair of nitrogen-rich
Wolf-Rayet stellar models characterized by differing hydrogen abundances. We
find that modes with intermediate radial orders are destabilized by a kappa
mechanism operating on an opacity bump at an envelope temperature log T ~ 6.25.
This `deep opacity bump' is due primarily to L-shell bound-free transitions of
iron. Periods of the unstable modes span ~ 11-21 hr in the model containing
some hydrogen, and ~ 3-12 hr in the hydrogen-depleted model. Based on the
latter finding, we suggest that self-excited g modes may be the source of the
9.8 hr-periodic variation of WR 123 recently reported by Lefevre et al. (2005).Comment: 5 pages, 3 figures, accepted by MNRAS letter
Characterizing the uncertainty in holddown post load measurements
In order to understand unexpectedly erratic load measurements in the launch-pad supports for the space shuttle, the sensitivities of the load cells in the supports were analyzed using simple probabilistic techniques. NASA engineers use the loads in the shuttle's supports to calculate critical stresses in the shuttle vehicle just before lift-off. The support loads are measured with 'load cells' which are actually structural components of the mobile launch platform which have been instrumented with strain gauges. Although these load cells adequately measure vertical loads, the horizontal load measurements have been erratic. The load measurements were simulated in this study using Monte Carlo simulation procedures. The simulation studies showed that the support loads are sensitive to small deviations in strain and calibration. In their current configuration, the load cells will not measure loads with sufficient accuracy to reliably calculate stresses in the shuttle vehicle. A simplified model of the holddown post (HDP) load measurement system was used to study the effect on load measurement accuracy for several factors, including load point deviations, gauge heights, and HDP geometry
ECONOMIC IMPACTS OF NOXIOUS WEEDS, OTHER WEEDS, AND TREE GROWTH, ON AGRICULTURAL PRODUCTION IN THE NEW ENGLAND TABLELANDS, NEW SOUTH WALES
The economic impact of weeds on farms in the New England Region of New South Wales is estimated from data from a cross -sectional survey. Weeds can be classed as noxious or declared plants, plants that the farmers perceived as weeds, and trees -- which many farmers also perceived as weeds. Variables were defined for several levels of intensity of infestation for each of these three classes of weeds. The impact of each these variables, on property income and stocking, was estimated through Cobb-Douglas production functions. The presence of very-heavy infestations of non-noxious weeds, and heavy infestations of non-noxious weeds, were found to be associated with reductions in income. In total, the income of the representative property would be increased by 15 per cent, ceteris paribus, if these infestations were removed.Weeds, trees, income, stocking, Farm Management,
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