3,670 research outputs found
Constraints on Dark Photon from Neutrino-Electron Scattering Experiments
A possible manifestation of an additional light gauge boson , named
as Dark Photon, associated with a group is studied in neutrino
electron scattering experiments. The exclusion plot on the coupling constant
and the dark photon mass is obtained. It is shown
that contributions of interference term between the dark photon and the
Standard Model are important. The interference effects are studied and compared
with for data sets from TEXONO, GEMMA, BOREXINO, LSND as well as CHARM II
experiments. Our results provide more stringent bounds to some regions of
parameter space.Comment: 22 pages, 6 figures, 2 tables, text improved, fig.6 updated,
references adde
Attenuation of Traffic Induced Ground Borne Vibrations due to Heavy Vehicles
Traffic induced vibrations, which are transmitted through the ground, may interfere with the proper operation of vibration sensitive equipments and cause nuisance on local population. Influence of these vibrations on surrounding buildings and sensitive devices play an important role on acceptance of the projects. In this study, main objective is the estimation of ground-borne vibration levels due to operation of heavy vehicles at two different sites where soil type and stratification significantly differs. For this purpose, site specific vibration surveys are conducted. A series of dynamic finite element modeling analyses are performed to predict actual vibration records at measurement points. Parameters used in finite element modeling are obtained through geotechnical and geophysical surveys conducted at the site. Modeling results are in good agreement with the actual vibration levels in the considered frequency range. Frequency range of dominant structural responses due to ground borne vibrations induced by heavy vehicles is found to be between 10 Hz to 50 Hz for a single degree of freedom system with 3% damping. Calibrated finite element models are further used to predict the attenuation of vibrations with distance from the source. Slightly better wave attenuation is observed in soil site compared to the rock site
Statistics of Largest Loops in a Random Walk
We report further findings on the size distribution of the largest neutral
segments in a sequence of N randomly charged monomers [D. Ertas and Y. Kantor,
Phys. Rev. E53, 846 (1996); cond-mat/9507005]. Upon mapping to one--dimensional
random walks (RWs), this corresponds to finding the probability distribution
for the size L of the largest segment that returns to its starting position in
an N--step RW. We primarily focus on the large N, \ell = L/N << 1 limit, which
exhibits an essential singularity. We establish analytical upper and lower
bounds on the probability distribution, and numerically probe the distribution
down to \ell \approx 0.04 (corresponding to probabilities as low as 10^{-15})
using a recursive Monte Carlo algorithm. We also investigate the possibility of
singularities at \ell=1/k for integer k.Comment: 5 pages and 4 eps figures, requires RevTeX, epsf and multicol.
Postscript file also available at
http://cmtw.harvard.edu/~deniz/publications.htm
Harnack Inequality and Regularity for a Product of Symmetric Stable Process and Brownian Motion
In this paper, we consider a product of a symmetric stable process in
and a one-dimensional Brownian motion in . Then we
define a class of harmonic functions with respect to this product process. We
show that bounded non-negative harmonic functions in the upper-half space
satisfy Harnack inequality and prove that they are locally H\"older continuous.
We also argue a result on Littlewood-Paley functions which are obtained by the
-harmonic extension of an function.Comment: 23 page
Monitoring spatial sustainable development: Semi-automated analysis of satellite and aerial images for energy transition and sustainability indicators
Solar panels are installed by a large and growing number of households due to
the convenience of having cheap and renewable energy to power house appliances.
In contrast to other energy sources solar installations are distributed very
decentralized and spread over hundred-thousands of locations. On a global level
more than 25% of solar photovoltaic (PV) installations were decentralized. The
effect of the quick energy transition from a carbon based economy to a green
economy is though still very difficult to quantify. As a matter of fact the
quick adoption of solar panels by households is difficult to track, with local
registries that miss a large number of the newly built solar panels. This makes
the task of assessing the impact of renewable energies an impossible task.
Although models of the output of a region exist, they are often black box
estimations. This project's aim is twofold: First automate the process to
extract the location of solar panels from aerial or satellite images and
second, produce a map of solar panels along with statistics on the number of
solar panels. Further, this project takes place in a wider framework which
investigates how official statistics can benefit from new digital data sources.
At project completion, a method for detecting solar panels from aerial images
via machine learning will be developed and the methodology initially developed
for BE, DE and NL will be standardized for application to other EU countries.
In practice, machine learning techniques are used to identify solar panels in
satellite and aerial images for the province of Limburg (NL), Flanders (BE) and
North Rhine-Westphalia (DE).Comment: This document provides the reader with an overview of the various
datasets which will be used throughout the project. The collection of
satellite and aerial images as well as auxiliary information such as the
location of buildings and roofs which is required to train, test and validate
the machine learning algorithm that is being develope
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