3,083 research outputs found
User Guide for AutoCSM: Automated Capacity Spectrum Method of Analysis
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A multiple replica approach to simulate reactive trajectories
A method to generate reactive trajectories, namely equilibrium trajectories
leaving a metastable state and ending in another one is proposed. The algorithm
is based on simulating in parallel many copies of the system, and selecting the
replicas which have reached the highest values along a chosen one-dimensional
reaction coordinate. This reaction coordinate does not need to precisely
describe all the metastabilities of the system for the method to give reliable
results. An extension of the algorithm to compute transition times from one
metastable state to another one is also presented. We demonstrate the interest
of the method on two simple cases: a one-dimensional two-well potential and a
two-dimensional potential exhibiting two channels to pass from one metastable
state to another one
Capacity and Scale Inefficiency: Application of Data Envelopment Analysis in the Case of the French Seaweed Fleet
Data Envelopment Analysis (DEA) models are applied to the main French seaweed fleet to examine capacity output, capacity utilization, and scale inefficiency. Coastal seaweed vessels target only one outputĂâkelpĂâwith the same gear but with different input level combinations. The fishery is seasonal and subject mainly to input regulations, especially a one trip per day regulation implemented in 1987. The consequence was a decline in total observed output and a fall in capacity output and efficient output. Only the largest vessels and a few small vessels harvesting without this regulatory constraint operate at the optimal scale. The question of a change in regulation, especially a shift to an individual quota system, is raised.Data Envelopment Analysis, capacity, capacity utilizations, cale inefficiency, production frontier, seaweed, fleet, Q22, Resource /Energy Economics and Policy,
On the length of one-dimensional reactive paths
Motivated by some numerical observations on molecular dynamics simulations,
we analyze metastable trajectories in a very simplecsetting, namely paths
generated by a one-dimensional overdamped Langevin equation for a double well
potential. More precisely, we are interested in so-called reactive paths,
namely trajectories which leave definitely one well and reach the other one.
The aim of this paper is to precisely analyze the distribution of the lengths
of reactive paths in the limit of small temperature, and to compare the
theoretical results to numerical results obtained by a Monte Carlo method,
namely the multi-level splitting approach
A BIOECONOMIC ANALYSIS OF THE IMPACT OF DECOMMISSIONING PROGRAMS: APPLICATION TO A LIMITED-ENTRY FRENCH SCALLOP FISHERY
The objective of this paper is to assess the benefits and costs of decommissioning policies aimed at reducing fleet capacity through premiums offered by the public authority to fishermen to scrap their vessels. A case study, the limited entry scallop fishery of the Saint Brieuc Bay, France, is used to consider the problem of excess capacity and to model the bioeconomic consequences of disinvestment behavior. Special attention is paid to the assessment of fishermen's willingness to leave the fishery and to the implementation of public policy in terms of budget level and premiums offered to the fishermen. Spreadsheet simulations show that the impact of decommissioning programs is positive in terms of net surplus, even in the case of increasing technical efficiency of the vessels.Resource /Energy Economics and Policy,
Efficient large deviation estimation based on importance sampling
We present a complete framework for determining the asymptotic (or
logarithmic) efficiency of estimators of large deviation probabilities and rate
functions based on importance sampling. The framework relies on the idea that
importance sampling in that context is fully characterized by the joint large
deviations of two random variables: the observable defining the large deviation
probability of interest and the likelihood factor (or Radon-Nikodym derivative)
connecting the original process and the modified process used in importance
sampling. We recover with this framework known results about the asymptotic
efficiency of the exponential tilting and obtain new necessary and sufficient
conditions for a general change of process to be asymptotically efficient. This
allows us to construct new examples of efficient estimators for sample means of
random variables that do not have the exponential tilting form. Other examples
involving Markov chains and diffusions are presented to illustrate our results.Comment: v1: 34 pages, 8 figures; v2: Typos corrected; v3: More mathematical
version containing technical modifications in Assumption 2, Assumption 3, and
Eq. (53) needed in some of the proof
An audiovisual attention model for natural conversation scenes
International audienceClassical visual attention models neither consider social cues, such as faces, nor auditory cues, such as speech. However, faces are known to capture visual attention more than any other visual features, and recent studies showed that speech turn-taking affects the gaze of non-involved viewers. In this paper, we propose an audiovisual saliency model able to predict the eye movements of observers viewing other people having a conversation. Thanks to a speaker diarization algorithm, our audiovisual saliency model increases the saliency of the speakers compared to the addressees. We evaluated our model with eye-tracking data, and found that it significantly outperforms visual attention models using an equal and constant saliency value for all faces
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