52 research outputs found
Energy Consumption Characterization and Reduction Strategies for Milling Machine Tool Use
Since machine tools are used extensively throughout their functional life and consequently consuming valuable natural resources and emitting harmful pollutants during this time, this study reviews strategies for characterizing and reducing the energy consumption of milling machine tools during their use. The power demanded by a micromachining center while cutting low carbon steel under varied material removal rates was measured to model the specific energy of the machine tool. Thereafter the power demanded was studied for cutting aluminum and polycarbonate work pieces for the purpose of comparing the difference in cutting power demand relative to that of steel
Exergy analysis of incremental sheet forming
Research in the last 15 years has led to die-less incremental forming processes that are close to realization in an industrial setup. Whereas many studies have been carried out with the intention of investigating technical abilities and economic consequences, the ecological impact of incremental sheet forming (ISF) has not been studied so far. Using the concept of exergy analysis, two ISF technologies, namely single sided and double sided incremental forming, are investigated and compared to conventional forming and hydroforming. A second exergy analysis is carried out with the purpose of examining the environmental impact of different forming technologies from a supply chain perspective. Therefore, related upstream activities (die set production, aluminum sheet production and energy conversion and supply) are included into the exergy analysis. The entire supply chain is modeled with Matlab/Simulink. The results of both analyses suggest that ISF is environmentally advantageous for prototyping and small production runs.United States. Dept. of Energy (Award DE-EE0003460
Holographic renormalization and supersymmetry
Holographic renormalization is a systematic procedure for regulating
divergences in observables in asymptotically locally AdS spacetimes. For dual
boundary field theories which are supersymmetric it is natural to ask whether
this defines a supersymmetric renormalization scheme. Recent results in
localization have brought this question into sharp focus: rigid supersymmetry
on a curved boundary requires specific geometric structures, and general
arguments imply that BPS observables, such as the partition function, are
invariant under certain deformations of these structures. One can then ask if
the dual holographic observables are similarly invariant. We study this
question in minimal N = 2 gauged supergravity in four and five dimensions. In
four dimensions we show that holographic renormalization precisely reproduces
the expected field theory results. In five dimensions we find that no choice of
standard holographic counterterms is compatible with supersymmetry, which leads
us to introduce novel finite boundary terms. For a class of solutions
satisfying certain topological assumptions we provide some independent tests of
these new boundary terms, in particular showing that they reproduce the
expected VEVs of conserved charges.Comment: 70 pages; corrected typo
Qualitative analysis of the viability of autogenous fat grafts grafted in different environments of interstitial pressure. Preliminary results and description of a new experimental model in mini-pigs
The BPS spectrum of monopole operators in ABJM: towards a field theory description of the giant torus
We study the BPS spectrum of monopole operators in ABJM theory. First we work
out the complete spectrum of the chiral ring by using a semiclassical analysis
of the field theory compactified on a two sphere. By properly taking into
account the full quantization condition of monopole charges, we show that the
moduli space of ABJM theory with Chern-Simons level k, -k is a particular Z_k
cover of the symmetric product of C^4/Z_k. We also work out in detail the
spectrum of fluctuations around half-BPS monopole configurations and we find
candidate states for a dual BPS configuration to the giant torus solution found
by Nishioka and Takayanagi in the supergravity limit. We also discuss more
general BPS states.Comment: 33 pages, JHEP style. v2: added reference, fixed typos. v3: added
references, improved the discussion of various issue
Consistent truncations of supergravity and 1/2-BPS RG flows in 4d SCFTs
With the purpose of holographically describing flows from a large family of
four dimensional and conformal field theories, we
discuss truncations of seven dimensional supergravity to five dimensions. We
write explicitly the reduced gauged supergravity and find BPS equations for
simple configurations. Lifting these flows to eleven dimensions or Massive IIA
supergravity, we present string duals to RG flows from strongly coupled
conformal theories when deformed by marginal and/or relevant operators. We
further discuss observables common to infinite families of and
QFTs in this context.Comment: 28 pages plus appendixes. JHEP versio
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