16,879 research outputs found
Shell Cracking In Investment Casting with Laser Stereolithography Patterns
This paper presents an investigation of ceramic shell cracking during the burnout process
in investment casting with internally webbed laser stereolithography patterns. We hypothesize
that shell cracking will occur when the rupture temperature of the ceramic shell is lower than
both the glass transition temperature of the pattern material and the web· link buckling
temperature. The hypothesis is validated by our experimental observations which confirm the
numerical predictions from our fillite element analysis. This provides a basis for design of the
internal web geometry of a lithography pa.tternand evaluation ofthe burnolltprocesswithsuch a
pattern. We show the shell cracking and web link buckling temperatures to be functiollsofthe
pattern geometry (including the cross~sectional dimensions and span length of the web link) and
the shell thickness.Mechanical Engineerin
Thermalization of quark-gluon matter by 2-to-2 and 3-to-3 elastic scatterings
Thermalization of quark-gluon matter is studied with a transport equation
that includes contributions of 2-to-2 and 3-to-3 elastic scatterings.
Thermalization time is related to the squared amplitudes for the elastic
scatterings that are calculated in perturbative QCD.Comment: LaTex, 6 pages, 3 figures, talk presented at the 19th international
conference on ultra-relativistic nucleus-nucleus collisions, Shanghai, China,
Nov. 200
A General SU(2) Formulation for Quantum Searching with Certainty
A general quantum search algorithm with arbitrary unitary transformations and
an arbitrary initial state is considered in this work. To serach a marked state
with certainty, we have derived, using an SU(2) representation: (1) the
matching condition relating the phase rotations in the algorithm, (2) a concise
formula for evaluating the required number of iterations for the search, and
(3) the final state after the search, with a phase angle in its amplitude of
unity modulus. Moreover, the optimal choices and modifications of the phase
angles in the Grover kernel is also studied.Comment: 8 pages, 2 figure
Learning to be sociable: the evolution of homo economicus
“This is a pre-print of an article published in American Journal of Economics and Sociology, Vol. 67 (2), pp 265 - 286". Author's draftThis article studies the evolution of the economic man (Homo economicus) from its original conception until the current day. By analyzing the discourse of economic articles, we provide a chronological account of the economic man's intellectual and philosophical development as it evolved from what we term the philosophical age to the neoclassical age and finally to the strategic age. The article then shows how the economic man in the strategic age is slowly finding convergence with the sociological man (Homo sociologicus). A reconciliation of the two sapiens is difficult. However, recent papers on behavioral and experimental economics provide insights into a possible reconciliation. Our study argues that the purpose of the sociological man is to identify who he is, how he interacts with people within a society, and the antecedents to such behaviors. Homo economicus, however, has no overarching philosophical assumptions on what he values. The objectives of each discipline are different and, once one is mapped onto the other, it is unclear if there is truly any tension between them
A General Phase Matching Condition for Quantum Searching Algorithm
A general consideration on the phase rotations in quantum searching algorithm
is taken in this work. As four phase rotations on the initial state, the marked
states, and the states orthogonal to them are taken account, we deduce a phase
matching condition for a successful search. The optimal options for these phase
are obtained consequently.Comment: 3 pages, 3 figure
Composition-induced structural phase transitions in the (Ba1xLax)2In2O5+x (0pxp0.6) system
Composition-induced structural phase changes across the high temperature, fast oxide ion conducting (Ba1xLax)2In2O5+x, 0pxp0.6, system have been carefully analysed using hard mode infrared (IR) powder absorption spectroscopy, X-ray powder diffraction and electron diffraction. An orthorhombic brownmillerite to three-dimensionally disordered cubic perovskite phase transition in this system is signalled by a drastic change in slope of both wavenumber and average line widths of IR spectra as a function of composition. Some evidence is found for the existence of an intermediate tetragonal phase (previously reported to exist from electron diffraction data) around x 0:2: The new spectroscopic data have been used to compare microscopic and macroscopic strain parameters arising from variation in composition. The strain and spectroscopic data are consistent with firstorder character for the tetragonal-orthorhombic transition, while the cubic-tetragonal transition could be continuous. Differences between the variation with composition of spectral parameters and of macroscopic strain parameters are consistent with a substantial order/disorder component for the transitions. There is also evidence for precursor effects within the cubic structure before symmetry is broken
Tensor coupling effects on spin symmetry in anti-Lambda spectrum of hypernuclei
The effects of -tensor coupling on the spin
symmetry of spectra in -nucleus systems have
been studied with the relativistic mean-field theory. Taking
C+ as an example, it is found that the tensor coupling
enlarges the spin-orbit splittings of by an order of magnitude
although its effects on the wave functions of are negligible.
Similar conclusions has been observed in -nucleus of different
mass regions, including O+, Ca+ and
Pb+. It indicates that the spin symmetry in
anti-lambda-nucleus systems is still good irrespective of the tensor coupling.Comment: 12 pages, 3 figures
Generalized Misner-Sharp Energy in f(R) Gravity
We study generalized Misner-Sharp energy in gravity in a spherically
symmetric spacetime. We find that unlike the cases of Einstein gravity and
Gauss-Bonnet gravity, the existence of the generalized Misner-Sharp energy
depends on a constraint condition in the gravity. When the constraint
condition is satisfied, one can define a generalized Misner-Sharp energy, but
it cannot always be written in an explicit quasi-local form. However, such a
form can be obtained in a FRW universe and for static spherically symmetric
solutions with constant scalar curvature. In the FRW universe, the generalized
Misner-Sharp energy is nothing but the total matter energy inside a sphere with
radius , which acts as the boundary of a finite region under consideration.
The case of scalar-tensor gravity is also briefly discussed.Comment: Revtex, 17 pages, v2: some references added, to appear in PR
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