476 research outputs found
Three Attempts at Inflation Forecasting in Pakistan
This paper presents three empirical approaches to forecasting inflation in Pakistan. The preferred approach is a leading indicators model in which broad money growth and private sector credit growth help forecast inflation. A univariate approach also yields reasonable forecasts, but seems less suited to capturing turning points. A vector autoregressive (VAR) model illustrates how monetary developments can be described by a Phillips-curve type relationship. We deal with potential parameter instability on account of fundamental changes in Pakistanâs economic system by restricting our sample to more recent observations. Gregorian and Islamic calendar seasonality are addressed by using 12-month moving averages.Inflation, Forecasting, Pakistan
Numerical analysis of two phase fluid flow and heat transfer in a condenser.
A quasi-three-dimensional algorithm is developed to simulate two-phase fluid flow and heat transfer in the shell side of power plant condensers. The simulation method developed is based on the fundamental governing conservation equations of mass and momentum for both gas and liquid phases, and the air mass fraction conservation equation. In the proposed numerical method, the condenser shell side is subdivided into a number of domains normal to the cooling water flow direction. The three-dimensional effects due to the cooling water temperature difference are taken into account by a series of two dimensional calculations, each being for one domain. A porous media concept is employed to model the tube bank. The pressure drop balance concept is used to determine the inlet mass flow rate for each domain. A staggered grid is used to perform the discretization. The resulting discretized equations are solved using the SIMPLEC algorithm. The numerical predictions of an experimental steam condenser are compared with the available experimental results. The predicted results are in good agreement with the experimental data. The results also show an improvement over the results obtained using a single-phase model. Sensitivity studies are carried out for four different correlations of condensation heat transfer coefficient.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1994 .B64. Source: Masters Abstracts International, Volume: 34-02, page: 0853. Adviser: C. Zhang. Thesis (M.A.Sc.)--University of Windsor (Canada), 1995
A framework for detection and classification of events in neural activity
We present a method for the real time prediction of punctate events in neural
activity, based on the time-frequency spectrum of the signal, applicable both
to continuous processes like local field potentials (LFP) as well as to spike
trains. We test it on recordings of LFP and spiking activity acquired
previously from the lateral intraparietal area (LIP) of macaque monkeys
performing a memory-saccade task. In contrast to earlier work, where trials
with known start times were classified, our method detects and classifies
trials directly from the data. It provides a means to quantitatively compare
and contrast the content of LFP signals and spike trains: we find that the
detector performance based on the LFP matches the performance based on spike
rates. The method should find application in the development of neural
prosthetics based on the LFP signal. Our approach uses a new feature vector,
which we call the 2D cepstrum.Comment: 30 pages, 6 figures; This version submitted to the IEEE Transactions
in Biomedical Engineerin
Spin glasses without time-reversal symmetry and the absence of a genuine structural glass transition
We study the three-spin model and the Ising spin glass in a field using
Migdal-Kadanoff approximation. The flows of the couplings and fields indicate
no phase transition, but they show even for the three-spin model a slow
crossover to the asymptotic high-temperature behaviour for strong values of the
couplings. We also evaluated a quantity that is a measure of the degree of
non-self-averaging, and we found that it can become large for certain ranges of
the parameters and the system sizes. For the spin glass in a field the maximum
of non-self-averaging follows for given system size a line that resembles the
de Almeida-Thouless line. We conclude that non-self-averaging found in
Monte-Carlo simulations cannot be taken as evidence for the existence of a
low-temperature phase with replica-symmetry breaking. Models similar to the
three-spin model have been extensively discussed in order to provide a
description of structural glasses. Their theory at mean-field level resembles
the mode-coupling theory of real glasses. At that level the one-step replica
symmetry approach breaking predicts two transitions, the first transition being
dynamical and the second thermodynamical. Our results suggest that in real
finite dimensional glasses there will be no genuine transitions at all, but
that some features of mean-field theory could still provide some useful
insights.Comment: 11 pages, 11 figure
Interfacial Phenomena and Natural Local Time
This article addresses a modification of local time for stochastic processes,
to be referred to as `natural local time'. It is prompted by theoretical
developments arising in mathematical treatments of recent experiments and
observations of phenomena in the geophysical and biological sciences pertaining
to dispersion in the presence of an interface of discontinuity in dispersion
coefficients. The results illustrate new ways in which to use the theory of
stochastic processes to infer macro scale parameters and behavior from micro
scale observations in particular heterogeneous environments
Corrections for "Occupation and local times for skew Brownian motion with applications to dispersion across an interface"
We are making corrections and acknowledging colleagues that pointed out
mistakes in our recent paper titled "Occupation and local times for skew
Brownian motion with applications to dispersion across an interface" which was
published in Annals of Applied Probability (2011) 21(1) 183-214. Specifically
the corrections are: 1. The restriction of to non negative values in
Theorem 1.3 is not needed. But one has probabilistic interpretation only when
is non negative. 2. State the correct formulas in Corollary 3.3 as
their were computational errors in the original formulas. We thank Pierre
Etoir\'e and Miguel Martinez for pointing out these errors.Comment: Published in at http://dx.doi.org/10.1214/11-AAP775 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The Link Overlap and Finite Size Effects for the 3D Ising Spin Glass
We study the link overlap between two replicas of an Ising spin glass in
three dimensions using the Migdal-Kadanoff approximation and scaling arguments
based on the droplet picture. For moderate system sizes, the distribution of
the link overlap shows the asymmetric shape and large sample-to-sample
variations found in Monte Carlo simulations and usually attributed to replica
symmetry breaking. However, the scaling of the width of the distribution, and
the link overlap in the presence of a weak coupling between the two replicas
are in agreement with the droplet picture. We also discuss why it is impossible
to see the asymptotic droplet-like behaviour for moderate system sizes and
temperatures not too far below the critical temperature.Comment: 7 pages, 10 figure
Fear of Floating: An optimal discretionary monetary policy analysis
This paper explores the idea that âFear of Floatingâ and accompanying pro-cyclical interest rate policies observed in the case of some emerging market economies may be justified as an optimal discretionary monetary policy response to shocks. The paper also examines how the differences in monetary policies may lead to different degrees of this fear. These questions are addressed with a small open economy, new- Keynesian model with endogenous capital accumulation and sticky prices. The economy consists of two sectors- traded and non-traded. International credit markets are assumed to be imperfect, so that only the traded sector enjoys the ability to borrow internationally in foreign currency. The firms in the traded sector could potentially hold a large proportion of their debt in foreign currency, while the liabilities of the non-traded sector firms are entirely denominated in the domestic currency. Domestic exchange rate volatility adversely affects the balance sheets of the traded sector firms, while interest rate volatility creates problems for the firms in the non-traded sector. In such a situation, the monetary authorities face a dilemma when reacting to shocks. The numerical solution of the model indicates that the central bankâs reaction to shocks depends not only on the net effect of exchange rate movements on output gap and inflation, but also on the relative weight the central bank allocates to stabilizing output in the traded sector as against the non-traded sector. A central bank that assigns relatively higher importance to output stability in the traded goods sector also displays greater aversion for exchange rate volatility.fear of floating, exchange rates, exchnage rate volatility, monetary policy, emerging countries
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