110,458 research outputs found
A similarity law for stressing rapidly heated thin-walled cylinders
When a thin cylindrical shell of uniform thickness is very rapidly heated by hot high-pressure gas flowing inside the shell, the temperature of material decreases steeply from a high temperature at the inside surface to ambient temperatures at the outside surface. Young's modulus of material thus varies. The purpose of the present paper is to reduce the problem of stress analysis of such a cylinder to an equivalent problem in conventional cylindrical shell without temperature gradient in the wall. The equivalence concept is expressed as a series of relations between the quantities for the hot cylinder and the quantities for the cold cylinder. These relations give the similarity law whereby strains for the hot cylinder can be simply deduced from measured strains on the cold cylinder and thus greatly simplify the problem of experimental stress analysis
Ambient Isotopic Meshing of Implicit Algebraic Surface with Singularities
A complete method is proposed to compute a certified, or ambient isotopic,
meshing for an implicit algebraic surface with singularities. By certified, we
mean a meshing with correct topology and any given geometric precision. We
propose a symbolic-numeric method to compute a certified meshing for the
surface inside a box containing singularities and use a modified
Plantinga-Vegter marching cube method to compute a certified meshing for the
surface inside a box without singularities. Nontrivial examples are given to
show the effectiveness of the algorithm. To our knowledge, this is the first
method to compute a certified meshing for surfaces with singularities.Comment: 34 pages, 17 Postscript figure
A COMPARISON OF EXTENDED SOURCE-FILTER MODELS FOR MUSICAL SIGNAL RECONSTRUCTION
China Scholarship Council (CSC)/
Queen Mary Joint PhD scholarship;
Royal Academy of Engineering Research Fellowshi
Topological Protection of Majorana Qubits
We study the stability of the topological quantum computation proposals
involving Majorana fermions against thermal fluctuations. We use a minimal
realistic model of a spinless px+ipy superconductor and consider effect of
excited midgap states localized in the vortex core as well as of transitions
above the bulk superconducting gap on the quasiparticle braiding,
interferometry-based qubit read-out schemes, and quantum coherence of the
topological qubits. We find that thermal occupation of the midgap states does
not affect adiabatic braiding operations but leads to a reduction in the
visibility of the interferometry measurements. We also consider quantum
decoherence of topological qubits at finite temperatures and calculate their
decay rate which is associated with the change of the fermion parity and, as
such, is exponentially suppressed at temperatures well below the bulk
excitation gap. Our conclusion is that the Majorana-based topological quantum
computing schemes are indeed protected by the virtue of the quantum
non-locality of the stored information and the presence of the bulk
superconducting gap.Comment: 8 pages, 1 figur
A computer solution for the dynamic load, lubricant film thickness, and surface temperatures in spiral-bevel gears
A computer method for determining the dynamic load between spiral bevel pinion and gear teeth contact along the path of contact is described. The dynamic load analysis governs both the surface temperature and film thickness. Computer methods for determining the surface temperature, and film thickness are presented along with results obtained for a pair of typical spiral bevel gears
A review of personal communications services
This article can be accessed from the link below - Copyright @ 2009 Nova Science Publishers, LtdPCS is an acronym for Personal Communications Service. PCS has two layers of
meaning. At the low layer, from the technical perspective, PCS is a 2G mobile
communication technology operating at the 1900 MHz frequency range. At the upper
layer, PCS is often used as an umbrella term that includes various wireless access and
personal mobility services with the ultimate goal of enabling users to freely communicate
with anyone at anytime and anywhere according to their demand. Ubiquitous PCS can be implemented by integrating the wireless and wireline systems on the basis of intelligent network (IN), which provides network functions of terminal and personal mobility. In this chapter, we focus on various aspects of PCS except location management. First we describe the motivation and technological evolution for personal communications. Then we introduce three key issues related to PCS: spectrum allocation, mobility, and standardization efforts. Since PCS involves several different communication
technologies, we introduce its heterogeneous and distributed system architecture. IN is
also described in detail because it plays a critical role in the development of PCS. Finally, we introduce the application of PCS and its deployment status since the mid-term of 1990’s.This work was supported in part by the National Natural Science Foundation of China
under Grant No. 60673159 and 70671020; the National High-Tech Research and Development Plan of China under Grant No. 2006AA01Z214, and the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1
Haar expectations of ratios of random characteristic polynomials
We compute Haar ensemble averages of ratios of random characteristic
polynomials for the classical Lie groups K = O(N), SO(N), and USp(N). To that
end, we start from the Clifford-Weyl algebera in its canonical realization on
the complex of holomorphic differential forms for a C-vector space V. From it
we construct the Fock representation of an orthosymplectic Lie superalgebra osp
associated to V. Particular attention is paid to defining Howe's oscillator
semigroup and the representation that partially exponentiates the Lie algebra
representation of sp in osp. In the process, by pushing the semigroup
representation to its boundary and arguing by continuity, we provide a
construction of the Shale-Weil-Segal representation of the metaplectic group.
To deal with a product of n ratios of characteristic polynomials, we let V =
C^n \otimes C^N where C^N is equipped with its standard K-representation, and
focus on the subspace of K-equivariant forms. By Howe duality, this is a
highest-weight irreducible representation of the centralizer g of Lie(K) in
osp. We identify the K-Haar expectation of n ratios with the character of this
g-representation, which we show to be uniquely determined by analyticity, Weyl
group invariance, certain weight constraints and a system of differential
equations coming from the Laplace-Casimir invariants of g. We find an explicit
solution to the problem posed by all these conditions. In this way we prove
that the said Haar expectations are expressed by a Weyl-type character formula
for all integers N \ge 1. This completes earlier work by Conrey, Farmer, and
Zirnbauer for the case of U(N).Comment: LaTeX, 70 pages, Complex Analysis and its Synergies (2016) 2:
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