265,316 research outputs found
Human environmental heat transfer simulation with CFD – the advances and challenges
The modelling and prediction of human thermoregulatory responses and comfort have gone a long way during the past decades. Sophisticated and detailed human models, i.e. the active multi-nodal thermal models with physiological regulatory responses, have been developed and widely adopted
in both research and industrial practice. The recent trend is to integrate human models with environmental models in order to provide more insight into the thermal comfort issues, especially in the non-homogeneous and transient conditions. This paper reviews the logics and expectations of coupling human models with computational fluid dynamics
(CFD) models. One of main objectives of such approaches is to take the advantage of the high resolution achievable with the CFD, to replace the empirical methods used in the human models. We aim to initiate debates on the validity of this objective, and to identify the technical requirements
for achieving this goal. A simple experiment with 3D human models of different sizes and shapes is also reported. Initial results shows the presence of arms may be important. Further experiments are required to establish the impact of size and shape on simulation result
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Optimal funding and investment strategies in defined contribution pension plans under Epstein-Zin utility
A defined contribution pension plan allows consumption to be redistributed from the plan member’s working life to retirement in a manner that is consistent with the member’s personal preferences. The plan’s optimal funding and investment strategies therefore depend on the desired pattern of consumption over the lifetime of the member.
We investigate these strategies under the assumption that the member has an Epstein-Zin utility function, which allows a separation between risk aversion and the elasticity of intertemporal substitution, and we also take into account the member’s human capital.
We show that a stochastic lifestyling approach, with an initial high weight in equity-type investments and a gradual switch into bond-type investments as the retirement date approaches is an optimal investment strategy. In addition, the optimal contribution rate each year is not constant over the life of the plan but reflects trade-offs between the desire for current consumption, bequest and retirement savings motives at different stages in the life cycle, changes in human capital over the life cycle, and attitude to risk
Single-particle subband structure of Quantum Cables
We proposed a model of Quantum Cable in analogy to the recently synthesized
coaxial nanocable structure [Suenaga et al. Science, 278, 653 (1997); Zhang et
al. ibid, 281, 973 (1998)], and studied its single-electron subband structure.
Our results show that the subband spectrum of Quantum Cable is different from
either double-quantum-wire (DQW) structure in two-dimensional electron gas
(2DEG) or single quantum cylinder. Besides the double degeneracy of subbands
arisen from the non-abelian mirrow reflection symmetry, interesting
quasicrossings (accidental degeneracies), anticrossings and bundlings of
Quantum Cable energy subbands are observed for some structure parameters. In
the extreme limit (barrier width tends to infinity), the normal degeneracy of
subbands different from the DQW structure is independent on the other structure
parameters.Comment: 12 pages, 9 figure
Quantum Cable as transport spectroscopy of 1D DOS of cylindrical quantum wires
We considered the proposed Quantum Cable as a kind of transport spectroscopy
of one-dimensional (1D) density of states (DOS) of cylindrical quantum wires.
By simultaneously detecting the direct current through the cylindrical quantum
wire and the leaked tunneling current into the neighboring wire at desired
temperatures, one can obtain detailed information about 1D DOS and subband
structure of cylindrical quantum wires.Comment: 7 pages, 4 figures, late
A Unified and Complete Construction of All Finite Dimensional Irreducible Representations of gl(2|2)
Representations of the non-semisimple superalgebra in the standard
basis are investigated by means of the vector coherent state method and
boson-fermion realization. All finite-dimensional irreducible typical and
atypical representations and lowest weight (indecomposable) Kac modules of
are constructed explicitly through the explicit construction of all
particle states (multiplets) in terms of boson and fermion
creation operators in the super-Fock space. This gives a unified and complete
treatment of finite-dimensional representations of in explicit form,
essential for the construction of primary fields of the corresponding current
superalgebra at arbitrary level.Comment: LaTex file, 23 pages, two references and a comment added, to appear
in J. Math. Phy
Interacting Individuals Leading to Zipf's Law
We present a general approach to explain the Zipf's law of city distribution.
If the simplest interaction (pairwise) is assumed, individuals tend to form
cities in agreement with the well-known statisticsComment: 4 pages 2 figure
Quantum Computing via The Bethe Ansatz
We recognize quantum circuit model of computation as factorisable scattering
model and propose that a quantum computer is associated with a quantum
many-body system solved by the Bethe ansatz. As an typical example to support
our perspectives on quantum computation, we study quantum computing in
one-dimensional nonrelativistic system with delta-function interaction, where
the two-body scattering matrix satisfies the factorisation equation (the
quantum Yang--Baxter equation) and acts as a parametric two-body quantum gate.
We conclude by comparing quantum computing via the factorisable scattering with
topological quantum computing.Comment: 6 pages. Comments welcom
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