29,703 research outputs found
Coupled coarse graining and Markov Chain Monte Carlo for lattice systems
We propose an efficient Markov Chain Monte Carlo method for sampling
equilibrium distributions for stochastic lattice models, capable of handling
correctly long and short-range particle interactions. The proposed method is a
Metropolis-type algorithm with the proposal probability transition matrix based
on the coarse-grained approximating measures introduced in a series of works of
M. Katsoulakis, A. Majda, D. Vlachos and P. Plechac, L. Rey-Bellet and
D.Tsagkarogiannis,. We prove that the proposed algorithm reduces the
computational cost due to energy differences and has comparable mixing
properties with the classical microscopic Metropolis algorithm, controlled by
the level of coarsening and reconstruction procedure. The properties and
effectiveness of the algorithm are demonstrated with an exactly solvable
example of a one dimensional Ising-type model, comparing efficiency of the
single spin-flip Metropolis dynamics and the proposed coupled Metropolis
algorithm.Comment: 20 pages, 4 figure
Analysis of Crowdsourced Sampling Strategies for HodgeRank with Sparse Random Graphs
Crowdsourcing platforms are now extensively used for conducting subjective
pairwise comparison studies. In this setting, a pairwise comparison dataset is
typically gathered via random sampling, either \emph{with} or \emph{without}
replacement. In this paper, we use tools from random graph theory to analyze
these two random sampling methods for the HodgeRank estimator. Using the
Fiedler value of the graph as a measurement for estimator stability
(informativeness), we provide a new estimate of the Fiedler value for these two
random graph models. In the asymptotic limit as the number of vertices tends to
infinity, we prove the validity of the estimate. Based on our findings, for a
small number of items to be compared, we recommend a two-stage sampling
strategy where a greedy sampling method is used initially and random sampling
\emph{without} replacement is used in the second stage. When a large number of
items is to be compared, we recommend random sampling with replacement as this
is computationally inexpensive and trivially parallelizable. Experiments on
synthetic and real-world datasets support our analysis
The small and medium enterprises Act as catalyst for economic growth and development in Pakistan: Economic growth and development perspective
This paper explores the value of small and medium enterprises for the economic growth and development especially in Pakistan. Moreover, it
assesses the usage of information technology in SMEs sector of Pakistan. According to the recent Census of Establishments conducted by the Federal
Bureau of Statistics (FBS) there are about 3.2 million economic establishments in Pakistan. Out of these Small & Medium sized enterprises
(SMEs) (with employment base up to 99) constitute 90% of all private
enterprises employing approximately 78% of non-agriculture labor force1.
SMEs contributed over 30% to GDP, 25% in export earnings besides sharing
35% in manufacturing value addition2. The paper suggests that SMEs act as a
catalyst to economical growth and development where IT embedded in their
operations, planning and decisions like Hong Kong, Denmark and USA.
Many other societies also place great value on the small and medium
enterprises and encourage their activity. In fact, wealth and a high majority of
jobs are created by small & medium businesses in the world. As a result,
many experienced business people, political leaders, economists, and
educators believe that fostering a robust small and medium business culture
will maximize individual and collective economic and social success on a
local, national, and global scale. It is recommended that SMEs may be offered
access to inexpensive capital, tax exemptions and management advice &
experiences and IT infrastructure which further leads toward the economical
growth & development. The economical growth and development in a country can brings happiness and prosperity to its nation
Does the Culture and Practice of Allotment Holding within Oxford help to build a Sustainable Local Economy?
An allotment is defined as a piece of land usually about 250m² in size, which can be rented from the council in order to grow fruit and vegetables for you and your family.
The study examines the culture and practice of allotment holding in Oxford and to assess if this element of self-sufficiency could benefit the community and to what extent allotments can help to build a sustainable local economy. Furthermore the study looks at the inclusion of allotments into Agenda 21 and rates Oxford City allotments using the Governments Sustainable Development Indicators.
The research was based on ten face-to-face interviews with councillors and allotment holders as well as a survey of one hundred local plot holders. The findings from these interviews indicate that allotments within Oxford can be classified as sustainable when ranked against the Sustainable Development Indicators. Further to this, the study highlighted a new trend in allotment holding with a younger generation of people taking up the pastime.
Due to the small sample size these findings cannot be classed as representative of the whole of Oxford, consequently generalisations cannot be made. Never the less the study provides useful insights into allotment holding and its role within sustainable development
Coarse-graining schemes for stochastic lattice systems with short and long-range interactions
We develop coarse-graining schemes for stochastic many-particle microscopic
models with competing short- and long-range interactions on a d-dimensional
lattice. We focus on the coarse-graining of equilibrium Gibbs states and using
cluster expansions we analyze the corresponding renormalization group map. We
quantify the approximation properties of the coarse-grained terms arising from
different types of interactions and present a hierarchy of correction terms. We
derive semi-analytical numerical schemes that are accompanied with a posteriori
error estimates for coarse-grained lattice systems with short and long-range
interactions.Comment: 31 pages, 2 figure
- …