The main goal of this chapter consists in revising technical building
aspects concerning the tabi... more The main goal of this chapter consists in revising technical building aspects concerning the tabique construction. Tabique is a traditional building technique which applies raw building materials such as timber and earth, for example. External and partition walls are the main tabique building components, which may have a relevant structural performance in the overall stability of a building. In general, the traditional tabique buildings are facing high levels of degradation. This problem is mainly due to the lack of maintenance and technical knowledge. Therefore, reconstruction processes of this type of buildings also require accurate and updated technical information related to materials, to building details, to the main likely pathologies, to the knowledge of the physical and mechanical behaviour of the building components, to the reinforcement solutions, among other aspects. This research work intends to give some guidance in this context and to make a parallel analysis between the Portuguese and the Turkish tabique constructions.
Proceedings of 2002 IEEE 10th Digital Signal Processing Workshop, 2002 and the 2nd Signal Processing Education Workshop., 2002
Teaching DSP concepts and algorithms can be very frustrating because students don't realize how t... more Teaching DSP concepts and algorithms can be very frustrating because students don't realize how to apply the concepts to solve real problems. Most of the DSP courses avoid the implementation of real-time DSP algorithms because it is a time consuming task. To minimize this drawback we developed a hardware expansion for the DSKC3X. We also have implemented a software framework that allows students to easily debug real-time DSP's algorithms. We also present and discuss the syllabus of an elective course targeted to the Electronics and Telecomunications diploma at the University of Aveiro.
A silicone rubber tray with embedded optical fibre sensors is produced in this work. Two fibre Br... more A silicone rubber tray with embedded optical fibre sensors is produced in this work. Two fibre Bragg grating (FBG) sensors are embedded in silicone rubber to enhance their sensitivity. When the rubber tray is subjected to transversal load the wavelength shift of the FBG sensors increases thanks to the coupling with the low stiffness host material. The linear dependence of the Bragg wavelength shift was measured to be 7.64 nm/Pa. A good response of the FBG sensor is observed when embedded in silicone; the sensibility to the applied load was found to be 0.0033 nm/g. This paper reports the first results on the development of a prototype of a weight measuring system using fibre Bragg gratings embedded in a silicone rubber tray.
Este artigo trata o tema da classificação automática de peças de barro através da análise da sua ... more Este artigo trata o tema da classificação automática de peças de barro através da análise da sua resposta sonora a um impulso mecânico. Consideraram-se para teste dois tijolos pré-classificados. Efectuaram-se diversos estudos em que se simularam diferentes métodos de classificação. Implementou-se um destes métodos numa plataforma de DSP, a operar em tempo-real, tendo por entrada unicamente o sinal de um microfone. Concluiu-se que o desempenho do método implementado é satisfatório, mesmo em condições de ruído ambiente. Com algum desenvolvimento adicional de adaptação, o método tem potencialidades para ser instalado numa linha de produção em ambiente industrial.
Aliphatic polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (P... more Aliphatic polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polydioxone (PDO) and others, have been commonly used in biodegradable products. Hydrolytic and/or enzymatic chain cleavage of these materials leads to αhydroxyacids, which, in most cases, are ultimately assimilated in human body or in a composting environment. However, each of these has some shortcomings, in terms of mechanical properties and degradation time, which restrict its applications. The combination of these materials, by copolymerization or blending, enables a range of mechanical properties and degradation rates. These are extremely promising approaches which can improve or tune the original properties of the polymers. A composite solution of several materials with different degradation rates also enables tuning the rate of degradation of a device and the mechanical properties. After immersion of an aliphatic polyester device, diffusion occurs very rapidly compared to hydrolysis. Therefore, it is usually considered that hydrolysis of ester bonds starts homogeneously and has traditionally been modelled according to a first order kinetics. In this experimental study, fibres of PLA-PCL, PGA-PCL, PDO and PGA, with two different dimensions, were characterized in terms of their degradation rate under three different environments (water, NaCl and PBS) at constant temperature (37ºC). Weights and mechanical properties were measured after six different degradation stages. Stages durations were different depending on materials, according to the predicted degradation times. As other thermoplastics, they are viscoelastic materials. In this experimental study mechanical properties of fibres were compared at different strain rates.
We analyze genetic variation at fused1, a locus that is close to the centromere of the X chromoso... more We analyze genetic variation at fused1, a locus that is close to the centromere of the X chromosome-autosome (X/4) fusion in Drosophila americana. In contrast to other X-linked and autosomal genes, for which a lack of population subdivision in D. americana has been observed at the DNA level, we find strong haplotype structure associated with the alternative chromosomal arrangements. There are several derived fixed differences at fused1 (including one amino acid replacement) between two haplotype classes of this locus. From these results, we obtain an estimate of an age of approximately 0.61 million years for the origin of the two haplotypes of the fused1 gene. Haplotypes associated with the X/4 fusion have less DNA sequence variation at fused1 than haplotypes associated with the ancestral chromosome arrangement. The X/4 haplotypes also exhibit clinal variation for the allele frequencies of the three most common amino acid replacement polymorphisms, but not for adjacent silent polymo...
2012 Abstracts IEEE International Conference on Plasma Science, 2012
ABSTRACT form only given. A Laser-Wakefiled acceleration (LWFA) experiment, aiming the production... more ABSTRACT form only given. A Laser-Wakefiled acceleration (LWFA) experiment, aiming the production of high-quality electron relativistic beams, was performed at Astra-Gemini Laser Facility. The interaction was used sub-50 fs laser pulses with energies in the range 4 - 10 J and structured gas cells with lengths of 2 - 4 cm filled with hydrogen as target. Reliable and reproducible electron beams with energies close to 1 GeV were produced in a single stage. The use of plasma channels to enhance the acceleration process was also tested resulting in a significant energy gain signature.
ABSTRACT In the Theremin, the performer’s hand movements, detected by two antennas, control the p... more ABSTRACT In the Theremin, the performer’s hand movements, detected by two antennas, control the pitch and volume of the generated sound. The TheremUS builds on this concept by using ultrasonic sensing for hand position detection and processing all signals digitally, a distinct advantage in terms of versatility. Not only can different sound synthesis algorithms be programmed directly on the instrument but also it can be easily connected to other digital sound synthesis or multimedia devices; a MIDI interface was included for this purpose. The TheremUS also features translucent panels lit by controllable RGB LED devices. This makes it possible to specify sound-colour mappings in the spirit of the legendary Ocular Harpsichord by Castel.
Proceedings of the 22nd Annual Symposium on Integrated Circuits and System Design Chip on the Dunes - SBCCI '09, 2009
A low-voltage bandgap reference source design in CMOS AMS 0.35μm is presented. For establishing a... more A low-voltage bandgap reference source design in CMOS AMS 0.35μm is presented. For establishing a voltage reference of less than 1V, the current-mode technique is used. The current consumption of the proposed design is 84μA; the supply voltage is 1.2V, and presents a small die area of 0.015mm2. The average measurement results are: temperature coefficient of 114ppm/°C between [-25°C to
A plasma waveguide scheme for high-intensity laser guiding with densities and lengths suitable fo... more A plasma waveguide scheme for high-intensity laser guiding with densities and lengths suitable for laser-plasma particle accelerators is presented. This scheme uses a laser-triggered high-voltage discharge, presents negligible jitter, allows full access to the plasma, and can be scaled to large distances. Experimental results showing the feasibility of this scheme are presented.
IFIP Advances in Information and Communication Technology, 2011
This paper presents the initial results of a research project that aims to develop a method for l... more This paper presents the initial results of a research project that aims to develop a method for losses/leakage detection and household water consumption characterization through the detailed patterns analysis of signals generated by water meters. The Department of Civil Engineering (University of Coimbra) supports the research as part of a PhD Project. An experimental facility is used for signals acquisition and data analysis will be performed by using a pattern recognition algorithm that will identify the hydraulic devices in use. It is intended to develop and test some algorithm structures at various plumbing configuration forms to find the best one. In a second phase, a consumption analysis will be carried out using that algorithm to test its efficiency in inhabited houses. The expectation is to develop an efficient water monitoring tool that helps the users to follow-up and to control the water consumption using a computer or even a mobile device.
ABSTRACT In this article we review the prospects of laser wakefield accelerators as next generati... more ABSTRACT In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, x-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser–plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.
ABSTRACT In this work we present a bat monitoring system for wind farms. The proposed system incl... more ABSTRACT In this work we present a bat monitoring system for wind farms. The proposed system includes a thermal camera and an ultrasound acquisition device to detect and record bats that come into the detection range of each one of these devices. All events are registered simultaneously with climatic variables and sent to a central database using 3G/4G. The system was designed to allow several monitoring systems to send data to the central server at the same time. We expect this system to allow the determination of climatic conditions that favor bat activity, especially in the proximity of wind turbines, and to use this information to define shutdown strategies to mitigate bat mortality caused by these infrastructures.
Physical Review Special Topics - Accelerators and Beams, 2007
The extraordinary ability of space-charge waves in plasmas to accelerate charged particles at gra... more The extraordinary ability of space-charge waves in plasmas to accelerate charged particles at gradients that are orders of magnitude greater than in current accelerators has been well documented.
The main goal of this chapter consists in revising technical building
aspects concerning the tabi... more The main goal of this chapter consists in revising technical building aspects concerning the tabique construction. Tabique is a traditional building technique which applies raw building materials such as timber and earth, for example. External and partition walls are the main tabique building components, which may have a relevant structural performance in the overall stability of a building. In general, the traditional tabique buildings are facing high levels of degradation. This problem is mainly due to the lack of maintenance and technical knowledge. Therefore, reconstruction processes of this type of buildings also require accurate and updated technical information related to materials, to building details, to the main likely pathologies, to the knowledge of the physical and mechanical behaviour of the building components, to the reinforcement solutions, among other aspects. This research work intends to give some guidance in this context and to make a parallel analysis between the Portuguese and the Turkish tabique constructions.
Proceedings of 2002 IEEE 10th Digital Signal Processing Workshop, 2002 and the 2nd Signal Processing Education Workshop., 2002
Teaching DSP concepts and algorithms can be very frustrating because students don't realize how t... more Teaching DSP concepts and algorithms can be very frustrating because students don't realize how to apply the concepts to solve real problems. Most of the DSP courses avoid the implementation of real-time DSP algorithms because it is a time consuming task. To minimize this drawback we developed a hardware expansion for the DSKC3X. We also have implemented a software framework that allows students to easily debug real-time DSP's algorithms. We also present and discuss the syllabus of an elective course targeted to the Electronics and Telecomunications diploma at the University of Aveiro.
A silicone rubber tray with embedded optical fibre sensors is produced in this work. Two fibre Br... more A silicone rubber tray with embedded optical fibre sensors is produced in this work. Two fibre Bragg grating (FBG) sensors are embedded in silicone rubber to enhance their sensitivity. When the rubber tray is subjected to transversal load the wavelength shift of the FBG sensors increases thanks to the coupling with the low stiffness host material. The linear dependence of the Bragg wavelength shift was measured to be 7.64 nm/Pa. A good response of the FBG sensor is observed when embedded in silicone; the sensibility to the applied load was found to be 0.0033 nm/g. This paper reports the first results on the development of a prototype of a weight measuring system using fibre Bragg gratings embedded in a silicone rubber tray.
Este artigo trata o tema da classificação automática de peças de barro através da análise da sua ... more Este artigo trata o tema da classificação automática de peças de barro através da análise da sua resposta sonora a um impulso mecânico. Consideraram-se para teste dois tijolos pré-classificados. Efectuaram-se diversos estudos em que se simularam diferentes métodos de classificação. Implementou-se um destes métodos numa plataforma de DSP, a operar em tempo-real, tendo por entrada unicamente o sinal de um microfone. Concluiu-se que o desempenho do método implementado é satisfatório, mesmo em condições de ruído ambiente. Com algum desenvolvimento adicional de adaptação, o método tem potencialidades para ser instalado numa linha de produção em ambiente industrial.
Aliphatic polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (P... more Aliphatic polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polydioxone (PDO) and others, have been commonly used in biodegradable products. Hydrolytic and/or enzymatic chain cleavage of these materials leads to αhydroxyacids, which, in most cases, are ultimately assimilated in human body or in a composting environment. However, each of these has some shortcomings, in terms of mechanical properties and degradation time, which restrict its applications. The combination of these materials, by copolymerization or blending, enables a range of mechanical properties and degradation rates. These are extremely promising approaches which can improve or tune the original properties of the polymers. A composite solution of several materials with different degradation rates also enables tuning the rate of degradation of a device and the mechanical properties. After immersion of an aliphatic polyester device, diffusion occurs very rapidly compared to hydrolysis. Therefore, it is usually considered that hydrolysis of ester bonds starts homogeneously and has traditionally been modelled according to a first order kinetics. In this experimental study, fibres of PLA-PCL, PGA-PCL, PDO and PGA, with two different dimensions, were characterized in terms of their degradation rate under three different environments (water, NaCl and PBS) at constant temperature (37ºC). Weights and mechanical properties were measured after six different degradation stages. Stages durations were different depending on materials, according to the predicted degradation times. As other thermoplastics, they are viscoelastic materials. In this experimental study mechanical properties of fibres were compared at different strain rates.
We analyze genetic variation at fused1, a locus that is close to the centromere of the X chromoso... more We analyze genetic variation at fused1, a locus that is close to the centromere of the X chromosome-autosome (X/4) fusion in Drosophila americana. In contrast to other X-linked and autosomal genes, for which a lack of population subdivision in D. americana has been observed at the DNA level, we find strong haplotype structure associated with the alternative chromosomal arrangements. There are several derived fixed differences at fused1 (including one amino acid replacement) between two haplotype classes of this locus. From these results, we obtain an estimate of an age of approximately 0.61 million years for the origin of the two haplotypes of the fused1 gene. Haplotypes associated with the X/4 fusion have less DNA sequence variation at fused1 than haplotypes associated with the ancestral chromosome arrangement. The X/4 haplotypes also exhibit clinal variation for the allele frequencies of the three most common amino acid replacement polymorphisms, but not for adjacent silent polymo...
2012 Abstracts IEEE International Conference on Plasma Science, 2012
ABSTRACT form only given. A Laser-Wakefiled acceleration (LWFA) experiment, aiming the production... more ABSTRACT form only given. A Laser-Wakefiled acceleration (LWFA) experiment, aiming the production of high-quality electron relativistic beams, was performed at Astra-Gemini Laser Facility. The interaction was used sub-50 fs laser pulses with energies in the range 4 - 10 J and structured gas cells with lengths of 2 - 4 cm filled with hydrogen as target. Reliable and reproducible electron beams with energies close to 1 GeV were produced in a single stage. The use of plasma channels to enhance the acceleration process was also tested resulting in a significant energy gain signature.
ABSTRACT In the Theremin, the performer’s hand movements, detected by two antennas, control the p... more ABSTRACT In the Theremin, the performer’s hand movements, detected by two antennas, control the pitch and volume of the generated sound. The TheremUS builds on this concept by using ultrasonic sensing for hand position detection and processing all signals digitally, a distinct advantage in terms of versatility. Not only can different sound synthesis algorithms be programmed directly on the instrument but also it can be easily connected to other digital sound synthesis or multimedia devices; a MIDI interface was included for this purpose. The TheremUS also features translucent panels lit by controllable RGB LED devices. This makes it possible to specify sound-colour mappings in the spirit of the legendary Ocular Harpsichord by Castel.
Proceedings of the 22nd Annual Symposium on Integrated Circuits and System Design Chip on the Dunes - SBCCI '09, 2009
A low-voltage bandgap reference source design in CMOS AMS 0.35μm is presented. For establishing a... more A low-voltage bandgap reference source design in CMOS AMS 0.35μm is presented. For establishing a voltage reference of less than 1V, the current-mode technique is used. The current consumption of the proposed design is 84μA; the supply voltage is 1.2V, and presents a small die area of 0.015mm2. The average measurement results are: temperature coefficient of 114ppm/°C between [-25°C to
A plasma waveguide scheme for high-intensity laser guiding with densities and lengths suitable fo... more A plasma waveguide scheme for high-intensity laser guiding with densities and lengths suitable for laser-plasma particle accelerators is presented. This scheme uses a laser-triggered high-voltage discharge, presents negligible jitter, allows full access to the plasma, and can be scaled to large distances. Experimental results showing the feasibility of this scheme are presented.
IFIP Advances in Information and Communication Technology, 2011
This paper presents the initial results of a research project that aims to develop a method for l... more This paper presents the initial results of a research project that aims to develop a method for losses/leakage detection and household water consumption characterization through the detailed patterns analysis of signals generated by water meters. The Department of Civil Engineering (University of Coimbra) supports the research as part of a PhD Project. An experimental facility is used for signals acquisition and data analysis will be performed by using a pattern recognition algorithm that will identify the hydraulic devices in use. It is intended to develop and test some algorithm structures at various plumbing configuration forms to find the best one. In a second phase, a consumption analysis will be carried out using that algorithm to test its efficiency in inhabited houses. The expectation is to develop an efficient water monitoring tool that helps the users to follow-up and to control the water consumption using a computer or even a mobile device.
ABSTRACT In this article we review the prospects of laser wakefield accelerators as next generati... more ABSTRACT In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, x-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser–plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.
ABSTRACT In this work we present a bat monitoring system for wind farms. The proposed system incl... more ABSTRACT In this work we present a bat monitoring system for wind farms. The proposed system includes a thermal camera and an ultrasound acquisition device to detect and record bats that come into the detection range of each one of these devices. All events are registered simultaneously with climatic variables and sent to a central database using 3G/4G. The system was designed to allow several monitoring systems to send data to the central server at the same time. We expect this system to allow the determination of climatic conditions that favor bat activity, especially in the proximity of wind turbines, and to use this information to define shutdown strategies to mitigate bat mortality caused by these infrastructures.
Physical Review Special Topics - Accelerators and Beams, 2007
The extraordinary ability of space-charge waves in plasmas to accelerate charged particles at gra... more The extraordinary ability of space-charge waves in plasmas to accelerate charged particles at gradients that are orders of magnitude greater than in current accelerators has been well documented.
Proceedings of the IEEE Particle Accelerator Conference, 2007
The feasibility of Laser/Plasma Wakefield Accelerators depends upon the ability to efficiently lo... more The feasibility of Laser/Plasma Wakefield Accelerators depends upon the ability to efficiently load a bunch of electrons to the wakefield driven by a laser or an electron beam propagating through a plasma. Such accelerators are expected to operate in a nonlinear regime -the blowout regime-, where the driver is intense enough to push all plasma electrons aside. Since the properties of the accelerator are determined by the three dimensional shape of the wakefield in the blowout regime, a description of beam loading must involve the interaction between this shape and the accelerating electrons. In order for the quality of the accelerating beam to be high, the modification of the plasma structure due to the presence of the beam must be small. Maximizing the beam charge while maintaining its quality high requires tailoring of the beam profile. This tailored profile may then be scaled up for more powerful drivers.
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Books by J. Vieira
aspects concerning the tabique construction. Tabique is a traditional building technique
which applies raw building materials such as timber and earth, for example. External
and partition walls are the main tabique building components, which may have a
relevant structural performance in the overall stability of a building. In general, the
traditional tabique buildings are facing high levels of degradation. This problem is mainly due to the lack of maintenance and technical knowledge. Therefore,
reconstruction processes of this type of buildings also require accurate and
updated technical information related to materials, to building details, to the
main likely pathologies, to the knowledge of the physical and mechanical
behaviour of the building components, to the reinforcement solutions, among
other aspects. This research work intends to give some guidance in this context
and to make a parallel analysis between the Portuguese and the Turkish
tabique constructions.
Papers by J. Vieira
aspects concerning the tabique construction. Tabique is a traditional building technique
which applies raw building materials such as timber and earth, for example. External
and partition walls are the main tabique building components, which may have a
relevant structural performance in the overall stability of a building. In general, the
traditional tabique buildings are facing high levels of degradation. This problem is mainly due to the lack of maintenance and technical knowledge. Therefore,
reconstruction processes of this type of buildings also require accurate and
updated technical information related to materials, to building details, to the
main likely pathologies, to the knowledge of the physical and mechanical
behaviour of the building components, to the reinforcement solutions, among
other aspects. This research work intends to give some guidance in this context
and to make a parallel analysis between the Portuguese and the Turkish
tabique constructions.