854 research outputs found
Brownian motion in a truncated Weyl chamber
We examine the non-exit probability of a multidimensional Brownian motion
from a growing truncated Weyl chamber. Different regimes are identified
according to the growth speed, ranging from polynomial decay over
stretched-exponential to exponential decay. Furthermore we derive associated
large deviation principles for the empirical measure of the properly rescaled
and transformed Brownian motion as the dimension grows to infinity. Our main
tool is an explicit eigenvalue expansion for the transition probabilities
before exiting the truncated Weyl chamber
Uma aplicação ao armamento portátil do Corpo de Fuzileiros
O presente trabalho surgiu da necessidade de melhoria do Sistema de Gestão
de Stock implementado no Corpo de Fuzileiros. Tem por objetivo o desenho
e edificação de um Sistema de Gestão de existências inovador, na forma de uma
aplicação web, direcionado para o Armamento Portátil e seus acessórios.
Este trabalho insere-se no âmbito da gestão logística de recursos, nomeadamente
de armamento portátil e seus acessórios, tendo-se realizado uma Análise ABC
que permitiu avaliar a relevância do material. Este procedimento faculta uma gestão
mais eficiente do material existente, tendo em consideração o seu valor e criticidade
operacional.
O desenvolvimento do sistema informático de gestão assentou em dois softwares
de base: o MongoDB, para a Base de Dados não relacional, e o Python (e as
suas bibliotecas), para a edificação estrutural e gráfica, que, em conjunto, deram
vida a este sistema de gestão. Foram implementadas diversas ferramentas e funcionalidades,
que visam apoiar o utilizador no seu dia a dia, ao permitirem um
controlo simples e eficaz dos artigos a gerir. É exemplo o conhecimento permanente
da localização e estado de operacionalidade de todos os artigos, ou a possibilidade
de incluir os documentos de suporte à movimentação e gestão do material. Outras
ferramentas disponíveis são a emissão de fichas de inventário, essenciais no controlo
de existências físicas regularmente levado a cabo nos paióis, ou o acesso a gráficos
interativos que permitem adquirir, de forma rápida, a visão geral do material.
Apesar da complexidade das tarefas a que dá resposta, o sistema proposto
proporciona uma interface simples e intuitiva com o utilizador. Para além do caso
para que foi otimizada, será possível, com os necessários ajustes, o seu alargamento
a outras tipologias de material ou, implementação em outras unidades militares.This work arose from the need of improvement of the Stock Management
System currently implemented at the unit Corpo de Fuzileiros.
The main goals of this project were based on the design and construction
of an innovative Stock Management System for Portable Armament.
Considering the logistical nature of this project, an ABC Analysis of Logistic
Data was initially carried out, from which it was possible to identify the most
relevant stock units.
The development of the application “Sistema de Gestão de Armamento
Portátil” was based on two fundamental softwares: MongoDB, for the non-relational
database, and Python (and its libraries) for structural and graphical development,
which together brought this system to life.
As a management system, several tools and functionalities have been implemented
in this web application, which aim to support the user in their day-to-day
tasks, by allowing a simple and effective control of the items to be managed. An
example is the possibility of knowing the location and status of all items, through
the insertion of different types of records in the application, together with their official
documents. Other available tools are the issuance of inventory sheets, essential
to assist the user in the control of physical stocks regularly carried out in the storerooms,
or the access to interactive graphical charts that allows to acquire a quick
overview of the material.
Despite the complexity of the tasks to which it responds, the work developed
in this thesis was, from the beginning, thought in a simple and intuitive way. In
addition to its implementation in the Unit, this system has been developed to allow
its expansion to the rest of the material of the Unit or even its implementation in
other Units that would benefit from this Management System
Overcoming Missing and Incomplete Modalities with Generative Adversarial Networks for Building Footprint Segmentation
The integration of information acquired with different modalities, spatial
resolution and spectral bands has shown to improve predictive accuracies. Data
fusion is therefore one of the key challenges in remote sensing. Most prior
work focusing on multi-modal fusion, assumes that modalities are always
available during inference. This assumption limits the applications of
multi-modal models since in practice the data collection process is likely to
generate data with missing, incomplete or corrupted modalities. In this paper,
we show that Generative Adversarial Networks can be effectively used to
overcome the problems that arise when modalities are missing or incomplete.
Focusing on semantic segmentation of building footprints with missing
modalities, our approach achieves an improvement of about 2% on the
Intersection over Union (IoU) against the same network that relies only on the
available modality
On the use of a cascaded convolutional neural network for three-dimensional flow measurements using astigmatic PTV
Many applications in chemistry, biology and medicine use microfluidic devices to separate, detect and analyze samples on a miniaturized size-level. Fluid flows evolving in channels of only several tens to hundreds of micrometers in size are often of a 3D nature, affecting the tailored transport of cells and particles. To analyze flow phenomena and local distributions of particles within those channels, astigmatic particle tracking velocimetry (APTV) has become a valuable tool, on condition that basic requirements like low optical aberrations and particles with a very narrow size distribution are fulfilled. Making use of the progress made in the field of machine vision, deep neural networks may help to overcome these limiting requirements, opening new fields of applications for APTV and allowing them to be used by nonexpert users. To qualify the use of a cascaded deep convolutional neural network (CNN) for particle detection and position regression, a detailed investigation was carried out starting from artificial particle images with known ground truth to real flow measurements inside a microchannel, using particles with uni- and bimodal size distributions. In the case of monodisperse particles, the mean absolute error and standard deviation of particle depth-position of less than and about 1 [my]m were determined, employing the deep neural network and the classical evaluation method based on the minimum Euclidean distance approach. While these values apply to all particle size distributions using the neural network, they continuously increase towards the margins of the measurement volume of about one order of magnitude for the classical method, if nonmonodisperse particles are used. Nevertheless, limiting the depth of measurement volume in between the two focal points of APTV, reliable flow measurements with low uncertainty are also possible with the classical evaluation method and polydisperse tracer particles. The results of the flow measurements presented herein confirm this finding. The source code of the deep neural network used here is available on https://github.com/SECSY-Group/DNN-APTV
Comparison of the Accuracy of 2D and 3D Templating for Revision Total Hip Replacement
Introduction: Revision hip arthroplasty is a challenging surgical procedure, especially in
cases of advanced acetabular bone loss. Accurate preoperative planning can prevent complications
such as periprosthetic fractures or aseptic loosening. To date, the accuracy of three-dimensional
(3D) versus two-dimensional (2D) templating has been evaluated only in primary hip and knee
arthroplasty. Methods: We retrospectively investigated the accuracy of 3D personalized planning
of reinforcement cages (Burch Schneider) in 27 patients who underwent revision hip arthroplasty.
Personalized 3D modeling and positioning of the reinforcement cages were performed using computed tomography (CT) of the pelvis of each patient and 3D templates of the implant. To evaluate
accuracy, the sizes of the reinforcement cages planned in 2D and 3D were compared with the sizes of
the finally implanted cages. Factors that may potentially influence planning accuracy such as gender
and body mass index (BMI) were analyzed. Results: There was a significant difference (p = 0.003)
in the accuracy of correct size prediction between personalized 3D templating and 2D templating.
Personalized 3D templating predicted the exact size of the reinforcement cage in 96.3% of the patients,
while the exact size was predicted in only 55.6% by 2D templating. Regarding gender and BMI,
no statistically significant differences in planning accuracy either for 2D or 3D templating were
observed. Conclusion: Personalized 3D planning of revision hip arthroplasty using Burch Schneider
reinforcement cages leads to greater accuracy in the prediction of the required size of implants than
conventional 2D templating
Indirect Exchange Interaction between two Quantum Dots in an Aharonov-Bohm Ring
We investigate the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between
two spins located at two quantum dots embedded in an Aharonov-Bohm (AB) ring.
In such a system the RKKY interaction, which oscillates as a function of the
distance between two local spins, is affected by the flux. For the case of the
ferromagnetic RKKY interaction, we find that the amplitude of AB oscillations
is enhanced by the Kondo correlations and an additional maximum appears at half
flux, where the interaction is switched off. For the case of the
antiferromagnetic RKKY interaction, we find that the phase of AB oscillations
is shifted by pi, which is attributed to the formation of a singlet state
between two spins for the flux value close to integer value of flux.Comment: 10 pages, 5 figure
- …