21,767 research outputs found
Cellular automata models of traffic flow along a highway containing a junction
We examine various realistic generalizations of the basic cellular automaton
model describing traffic flow along a highway. In particular, we introduce a
{\em slow-to-start} rule which simulates a possible delay before a car pulls
away from being stationary. Having discussed the case of a bare highway, we
then consider the presence of a junction. We study the effects of acceleration,
disorderness, and slow-to-start behavior on the queue length at the entrance to
the highway. Interestingly, the junction's efficiency is {\it improved} by
introducing disorderness along the highway, and by imposing a speed limit.Comment: to appear in J. Phys. A:Math.& General. 15 pages, RevTeX, 3
Postscript figure
The Forecasting Capacity of Housing Price Expectations
This study captures the essential elements of the price expectations of market participants in a rising market. Adopting a forward-looking approach, this paper explores the effectiveness of expectations as an indicator of forthcoming housing price changes in Hong Kong. Examination of the quarterly survey data from December 2003 to September 2007 indicates that both homeowners and non-homeowners tend to overestimate the probability of future housing price increases yet underestimate its volatility. This adds weight to the argument that market participants are generally not rational in the prediction of price movement. Homeowners, investors and potential home buyers have more or less the same level of confidence about the future market outlook. Like non-owners, they expect higher prices. The number of correct forecasts exceeds incorrect forecasts, suggesting that overall price expectations are fairly close to realization. It can be broadly concluded that the aggregate price expectations in the long run can be an appropriate forecasting tool for future market performance.Price expectations; Forecastability; Housing market; Hong Kong
An equivalence principle for scalar forces
The equivalence of inertial and gravitational masses is a defining feature of
general relativity. Here, we clarify the status of the equivalence principle
for interactions mediated by a universally coupled scalar, motivated partly by
recent attempts to modify gravity at cosmological distances. Although a
universal scalar-matter coupling is not mandatory, once postulated, it is
stable against classical and quantum renormalizations in the matter sector. The
coupling strength itself is subject to renormalization of course. The scalar
equivalence principle is violated only for objects for which either the
graviton self-interaction or the scalar self-interaction is important---the
first applies to black holes, while the second type of violation is avoided if
the scalar is Galilean-symmetric.Comment: 4 pages, 1 figur
Approaching the ground states of the random maximum two-satisfiability problem by a greedy single-spin flipping process
In this brief report we explore the energy landscapes of two spin glass
models using a greedy single-spin flipping process, {\tt Gmax}. The
ground-state energy density of the random maximum two-satisfiability problem is
efficiently approached by {\tt Gmax}. The achieved energy density
decreases with the evolution time as
with a small prefactor and a scaling coefficient , indicating an
energy landscape with deep and rugged funnel-shape regions. For the
Viana-Bray spin glass model, however, the greedy single-spin dynamics quickly
gets trapped to a local minimal region of the energy landscape.Comment: 5 pages with 4 figures included. Accepted for publication in Physical
Review E as a brief repor
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