4,109 research outputs found
People counting system using existing surveillance video camera
The Casa da Música Foundation, responsible for the management of Casa da Música do Porto building, has the need to obtain statistical data related to the number of building’s visitors. This information is a valuable tool for the elaboration of periodical reports concerning the success of this cultural institution. For this reason it was necessary to develop a system capable of returning the number of visitors for a requested period of time.
This represents a complex task due to the building’s unique architectural design, characterized by very large doors and halls, and the sudden large number of people that pass through them in moments preceding and proceeding the different activities occurring in the building.
To achieve the technical solution for this challenge, several image processing methods, for people detection with still cameras, were first studied. The next step was the development of a real time algorithm, using OpenCV libraries and computer vision concepts,to count individuals with the desired accuracy. This algorithm includes the scientific and technical knowledge acquired in the study of the previous methods. The themes developed in this thesis comprise the fields of background maintenance, shadow and highlight detection, and blob detection and tracking.
A graphical interface was also built, to help on the development, test and tunning of the proposed system, as a complement to the work.
Furthermore, tests to the system were also performed, to certify the proposed techniques against a set of limited circumstances. The results obtained revealed that the algorithm was successfully applied to count the number of people in complex environments with reliable accuracy.A Fundação Casa da Música, responsável pela gestão do edifício da Casa da Música, tem a necessidade de obter dados estatísticos relativos ao número de visitantes. Esta informação é uma ferramenta valiosa para a elaboração periódica de relatórios de afluência para a avaliação do sucesso desta instituição cultural. Por este motivo existe a necessidade da elaboração de um sistema capaz de fornecer o número de visitantes para um determinado período de tempo.
Esta tarefa é dificultada pelas características arquitetônicas, únicas do edifício, com portas largas e amplos halls, e devido ao súbito número de pessoas que passam por estas áreas em momentos que antecedem e procedem concertos, ou qualquer outras actividades.
Para alcançar uma solução técnica para este desafio foi inicialmente elaborado um estado da arte relativo a métodos de processamento de imagem para deteção de pessoas com câmeras de vídeo. O passo seguinte foi, utilizando bibliotecas de OpenCV e conceitos de visão computacional, o desenvolvimento de um algoritmo em tempo real para contar pessoas com a precisão desejada. Este algoritmo inclui o conhecimento científico e técnico adquirido em métodos previamente estudados. Os temas desenvolvidos nesta tese compreendem os campos de manutenção do fundo, deteção de zonas sub e sobre iluminadas e deteção e seguimento de blobs.
Foi também construida uma interface gráfica para ajudar o desenvolvimento, teste e afinação do sistema proposto como complemento ao trabalho desenvolvido.
Além disso, perante um conjunto limitado de circunstâncias, foram efectuados testes ao sistema em ordem a certificar as técnicas propostas. Os resultados obtidos revelaram que o algoritmo foi aplicado com sucesso para contar pessoas em ambientes complexos com precisão
Empirical models for quantification of machining damage in composite materials
Dissertação para obtenção do Grau de Doutor em
Engenharia MecânicaThe tremendous growth which occurs at a global level of demand and use of composite materials brings with the need to develop new manufacturing tools and methodologies. One of the major uses of such materials, in particular plastics reinforced with carbon fibres, is their application in structural components for the aircraft industry with low weight and high stiffness. These components are produced in near-final form but the so-called secondary processes such as machining are often unavoidable. In this type of industry, drilling is the most frequent operation due to the need to obtain holes for riveting and fastening bolt assembly of structures. However, the problems arising from drilling, particularly the damage caused during the operation, may lead to rejection of components because it is an origin of lack of resistance. The delamination is the most important damage, as it causes a decrease of the mechanical properties of the components of an assembly and, irrefutably, a reduction of its reliability in use. It can also raise problems with regard to the tolerances of the assemblies. Moreover, the high speed machining is increasingly recognized to be a manufacturing technology that promotes productivity by reducing production times. However, the investigation whose focus is in high speed drilling is quite limited, and few studies on this subject have been found in the literature review. Thus, this thesis aims to investigate the effects of process variables in high speed drilling on the damage produced. The empirical models that relate the delamination damage, the thrust force and the torque with the process parameters were established using Response Surface Methodology. The process parameters considered as input factors were the spindle speed, the feed per tooth, the tool diameter and the workpiece thickness. A new method for fixing the workpiece was developed and tested. The results proved to be very promising since in the same cutting conditions and with this new methodology, it was observed a significant reduction of the delamination damage. Finally, it has been found that is possible to use high speed drilling, using conventional twist drills, to produce holes with good quality, minimizing the damage
Production and optimization of hybrid fibrillary gels by colloidal electrospinning
Electrospinning technique has proven to be a suitable approach to produce high surface area to volume ratio polymeric membranes with tailored architecture. To increase its functionality, a straightforward strategy can be the confinement of externally stimuli responsive systems, such as microgels. This combination enables the production of multifunctional composite systems.
This thesis reports the development of composite fibres through colloidal electrospinning constituted by polyvinylpyrrolidone (PVP) containing poly(N-isopropylacrylamide) (PNIPAAm) microgels. The focus of the dissertation deals with the optimization of the fibre precursor, PVP. In the first stage, an extensive study towards the production of PVP non-woven mats with high surface area to volume ratio was performed. The obtained non-woven mats were crosslinked using UV irradiation, a green and cost-effective technique, to ensure structure stability in the presence of a solvent (prevent dissolution). Non-woven mats were further characterized in terms of morphological, mechanical and swelling properties. In addition, the fibre precursor, PVP, was analysed through a process-dependent comparative study: non-woven mats vs. films. The most suitable electrospinning parameters were further used to confine PNIPAAm thermoresponsive microgels in PVP fibres through colloidal electrospinning. The system was further crosslinked and fully characterized to obtain a multiresponsive composite system.
This versatile approach is a starting point to design and produce composite multifunctional systems that could be tailored for a wide range of applications
SINAIS DE QUALIDADE E RASTREABILIDADE DE ALIMENTOS: UMA VISÃO SISTÊMICA
In this article, the concept of traceability in food quality control is systematized. The interfaces among traceability, labeling, brands, standards and certification are presented. In addition, the differences and connections between identification and traceability are explained. The asset specificity of information and of the organization structures required to implant tracing systems are outlined according to the Transaction Cost Economics (TCE). The importance and difficulty of establishing such systems are described as functions of government interests, as well as the interests of various agents in the agro-industrial system. In the examples, emphasis is placed on the soybean and beef chains.quality control, information systems, coordination., Food Consumption/Nutrition/Food Safety,
Portuguese households' stress tests : diagnosis and prospective analysis
Mestrado em FinançasA presente investigação analisa a vulnerabilidade financeira das famílias portuguesas e o impacto de choques macroeconómicos nessa vulnerabilidade. A análise empírica tem como base essencial o European Union Statistics on Income and Living Conditions (EU ? SILC 2010) para Portugal (5.182 famílias). Adoptando o teste de stress como metodologia procede-se à identificação do stress financeiro das famílias, através da adopção de medidas de diferentes níveis de vulnerabilidade baseadas nas margens financeiras. São realizados três tipos de cenários para avaliar o impacto na vulnerabilidade das famílias de três tipos de choques: um aumento da taxa de juro, um aumento da taxa de desemprego e um decréscimo do rendimento. Os resultados empíricos demonstram que a vulnerabilidade das famílias é afectada de modo insignificante por uma subida da taxa de juro. Por contrapartida, um aumento do desemprego e uma redução no nível de rendimento das famílias tem um impacto elevado. Estes resultados convergem com estudos empíricos recentemente realizados em outros países da Europa. A comparação da situação das famílias antes e depois da crise económica e financeira sugere uma degradação significativa da vulnerabilidade financeira das famílias, em particular daquelas pertencentes ao quartil de rendimento inferior e famílias monoparentais ou compostas por dois adultos com filhos menores.This research investigates the financial vulnerability of Portuguese households and the impact of macroeconomic shocks on it. The empirical analysis is mainly based on European Union Statistics on Income and Living Conditions (EU - SILC 2010) for Portugal (5,182 households). Using stress test methodologies, the financial stress of households is identified, adopting measures of different levels of vulnerability based on financial margins. Three types of scenario are constructed to assess the impact on family vulnerability of three different types of shocks: an increase in the interest rate, an increase in the unemployment rate and a decrease on income. The empirical results show that the vulnerability of households is weakly affected by rises in the interest rate. By contrast, the rise in unemployment and the decline in the level of household income have a high impact. These computed effects converge with other empirical studies recently conducted in other European countries. The comparison between the households' situation before and after the economic and financial crisis suggests a dramatic worsening of the financial vulnerability of households, particularly those in the lowest quartile of income and households composed by a single parent or couples with dependent children
Social interactions around public transportation
In this work, we explore how information services can
be used to improve the travel experience in public transportation
and reduce the perceived travel time. More specifically, we
describe the creation of a mobile application for assisting
passengers, which explores the integration of social networking
features into the traveling experience. The overall objective is to
understand how social networking concepts can become part of
the travel experience and enrich that experience in a way that
allows passengers to reduce the "psychological travel time" and
to change the perception of waiting. We have conducted a focus
group with 10 participants to elicit new forms of interaction
within the transportation system and uncover new directions for
integrating social network concepts. We have implemented some
of them in our own mobile app for public transportation and
shown how they can be combined with the more informative side
of those applications
Photography, landscape and modern architecture: Januário Godinho, Teófilo Rego and Álvaro Cardoso de Azevedo – The HICA conection
In the first half of the 20th century in Portugal, as the result of a policy based on agriculture and on a way of life in which access to more than a bare minimum of goods was denied, the Portuguese Estado Novo, presided over by António de Oliveira Salazar (1889-1970), maintained, until the 1940s, an indefinite stance in relation to industrialization which was reflected in weak management of the nation's hydrological resources and in the late creation of large hydroelectric power stations.
It was only in 1945, with the end of World War II, that favourable conditions were created for economic development founded on a basis of industrialization. At that time, due to their importance in bringing electrical power to the country and its consequent industrialization, hydroelectric plants for the production and distribution of electrical power began to be strongly encouraged by the Estado Novo.
A meeting between technology and architecture, these large projects introduced significant alterations to the territory of Portugal, bringing substantial modifications to the existing landscape. At locations that were far from the main centres of population, large building projects would be constructed, utilizing an architecture in which integration into the landscape and technology constituted environmental, historical and cultural values of immense interest.
The understanding of the importance of propaganda and of the crucial role of image in publicizing the large building projects that were undertaken can be clearly seen in the activities promoted by the Estado Novo. In publications and at major events, photographers and their work came to be a constant presence in public life, recording scenes that appeared to the Portuguese public to be illustrating moments of great national importance.
It is these photographs, much more so than the texts of the time, that can reach out to us today and allow us to go back to the past. Photography transports us from real, chronological time to a time of memory that is fixed in the image, replacing the real people and events that have long disappeared, the understanding of which helps us to reconstruct history.
The aim of this essay is precisely that of analysing the potential of photography as a tool for the development of new interpretations of the theory, criticism and history of modern architecture, with particular focus on a specific moment at the beginning of the second half of the 20th century during which several hydroelectric plants were built in the north of Portugal, interventions which led to the construction of a variety of new landscapes on national territory.Este texto foi co-financiado pela Fundação para a Ciência e a Tecnologia I.P. (PIDDAC) e pelo Fundo Europeu de Desenvolvimento Regional – FEDER, através do COMPETE – Programa Operacional Fatores de Competitividade (POFC), no âmbito do projecto "Fotografia, Arquitectura Moderna e a «Escola do Porto»: Interpretações em torno do Arquivo Teófilo Rego" (PTDC/ATP-AQI/4805/2012
Devonian Sedimentation in the SW boundary of the Ossa-Morena Zone: State of Art and Paleogeography
The Devonian sedimentary record of the Ossa-Morena Zone is scarce. In its southwestern domains, the Odivelas Limestone and correlatable units represent the single evidence of latest Early Devonian to Middle Devonia n (possibly into Frasnian) sedimentation in this area. Reefal and perireefa l sediments are frequently, but not always, associated to coeval volcanic rocks that probably supported atoll-like systems on the top of volcanic edifices. The northernmost occurrences are spatially associated with mississippian volcani c-sedimentary complexes. Their geometrical relation is still unclear, the limestones are possibly embedded as olitoliths, but can also be tectonically imbricated or simply reflecting draping of younger sediments around and above older (Devonian) sea-bed topography
Coordenação do sistema da carne bovina no Reino Unido: implicações da rastreabilidade e da tecnologia de informação
This paper discusses the traceability concept in the food business. Based on the transaction costs economics, it describes the adoption of traceability mechanisms in the UK beef market and examines the effects on the governance mechanisms in the production and distribution chain. The basic hypothesis is that, in the absence of information technology (IT), strictly coordinated mechanisms will occur. As the use of IT spreads, a decrease in information asymmetry and, consequently, more flexible governance structures may be observed.information asymmetry, information technology, electronic identification, beef chain coordination.,
- …