528 research outputs found
New DRIE-Patterned Electrets for Vibration Energy Harvesting
This paper is about a new manufacturing process aimed at developing stable
SiO2/Si3N4 patterned electrets using a Deep Reactive Ion Etching (DRIE) step
for an application in electret-based Vibration Energy Harvesters (e-VEH). This
process consists in forming continuous layers of SiO2/Si3N4 electrets in order
to limit surface conduction phenomena and is a new way to see the problem of
electret patterning. Experimental results prove that patterned electrets
charged by a positive corona discharge show excellent stability with high
surface charge densities that may reach 5mC/m^2 on 1.1\mu m-thick layers, even
with fine patterning and harsh temperature conditions (up to 250{\deg}C). This
paves the way to new e-VEH designs and manufacturing processes.Comment: Proc. European Energy Conference, 201
Legislate or liberate? A study of anarchist and parliamentary left approaches to animal advocacy in Britain
This thesis makes an original contribution to knowledge by exploring parliamentary left and anarchistic approaches to animal advocacy using a Critical Animal Studies (CAS) framework. This is significant because CAS is a field of scholarship which developed in order to theoretically support animal activists; nonetheless, in its focus on direct action and its rejection of reformist politics, CAS has too often ignored the legislative developments which are extremely important to most animal activists. Therefore, this thesis makes an overarching claim that CAS scholarship should treat the relationship between direct action and legislative reform more seriously. This thesis considers the relationship between direct action activists and legislative politics and as such makes a useful contribution to both CAS and wider animal rights scholarship. More broadly, the thesis provides a particularly useful assessment of one social movement at a time of rapidly changing moral, political and activist landscapes as Britain enters a new ‘age of dissent’. [Continues.
Dynamics of a self-gravitating thin cosmic string
We assume that a self-gravitating thin string can be locally described by
what we shall call a smoothed cone. If we impose a specific constraint on the
model of the string, then its central line obeys the Nambu-Goto equations. If
no constraint is added, then the worldsheet of the central line is a totally
geodesic surface.Comment: 20 pages, latex, 1 figure, final versio
Vortex in a weakly relativistic Bose gas at zero temperature and relativistic fluid approximation
The Bogoliubov procedure in quantum field theory is used to describe a
relativistic almost ideal Bose gas at zero temperature. Special attention is
given to the study of a vortex. The radius of the vortex in the field
description is compared to that obtained in the relativistic fluid
approximation. The Kelvin waves are studied and, for long wavelengths, the
dispersion relation is obtained by an asymptotic matching method and compared
with the non relativistic result.Comment: 20 page
Typologie des stations forestières du massif Sainte Victoire
Après de nombreuses observations sur le terrain, le traitement des données recueillies a permis de définir 26 types de stations, discriminés en premier lieu par le substrat. Pour chacun de ces types de stations, une liste d'essences adaptées est proposée, et les potentialités pastorales sont esquissées
Sound understanding of environmental, health and safety, clinical, and market aspects is imperative to clinical translation of nanomedicines
Some results on homoclinic and heteroclinic connections in planar systems
Consider a family of planar systems depending on two parameters and
having at most one limit cycle. Assume that the limit cycle disappears at some
homoclinic (or heteroclinic) connection when We present a method
that allows to obtain a sequence of explicit algebraic lower and upper bounds
for the bifurcation set The method is applied to two quadratic
families, one of them is the well-known Bogdanov-Takens system. One of the
results that we obtain for this system is the bifurcation curve for small
values of , given by . We obtain
the new three terms from purely algebraic calculations, without evaluating
Melnikov functions
Singing Beetles? Figuring out how male rhinoceros beetles produce their courtship songs.
Insects produce sound in wildly-diverse ways, from the vibrating wings of chirping crickets to the pulsating tympanum of whining of cicadas. Beetles (order: Coleoptera) use sound in aggressive displays, alarm calls, and courtship sequences. Although all beetles appear to generate sounds using stridulation, where a plectrum, or pick, is rubbed against a pars stridens, or file, species differ in the size and location of these structures, resulting in a diverse mechanistic array of sound production within this order. The Japanese rhinoceros beetle, Trypoxylus dichotomus, was recently observed stridulating during courtship sequences; however, the mechanism of sound production, including the body parts involved and their fine structure, were unknown. I used videos of singing males, topical applications of nail polish to putative file structures, and light and scanning electron microscopy (SEM), to localize and characterize the stridulatory apparatus. Here, I show that the pars stridens is located on the inside apical tip of each elytron, and it is scraped by a plectrum located on the dorsal surface of the abdomen. By either pumping the abdomen forward and back, or swiping it side to side, males are able to produce two distinct types of acoustic signals. Future studies will explore the properties of the male courtship song and the details of female preference
Statefinder -- a new geometrical diagnostic of dark energy
We introduce a new cosmological diagnostic pair called
Statefinder. The Statefinder is dimensionless and, like the Hubble and
deceleration parameters and , is constructed from the scale factor
of the Universe and its derivatives only. The parameter forms the next
step in the hierarchy of geometrical cosmological parameters used to study the
Universe after and , while the parameter is a linear combination
of and chosen in such a way that it does not depend upon the dark
energy density . The Statefinder pair is
algebraically related to the the dark energy pressure-to-energy ratio
and its time derivative, and sheds light on the nature of dark
energy/quintessence. Its properties allow to usefully differentiate between
different forms of dark energy with constant and variable , including a
cosmological constant (). The Statefinder pair can be determined to
very good accuracy from a SNAP type experiment.Comment: 7 pages, 3 figures. Final version to be published in JETP Lett.,
presentation shortened, references added and updated, consideration of brane
cosmological models included, conclusions unchange
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