Semi-destructive in situ tests as support to the assessment of a conservation process

This paper refers to the assessment on site by semi-destructive testing (SDT) methods of the consolidation efficiency of a conservation process developed by Henriques (2011) for structural and non-structural pine wood elements in service. This study was applied on scots pine wood (Pinus sylvestris L.) degraded by fungi after treatment with a biocidal product followed by consolidation with a polymeric product. This solution avoids substitutions of wood moderately degraded by fungi, improving its physical and mechanical characteristics. The consolidation efficiency was assessed on site by methods of drill resistance and penetration resistance. The SDT methods used showed good sensitivity to the conservation process and could evaluate their effectiveness. (C) 2015 Elsevier Ltd. All rights reserved.

Diagnostic performance of visual screening tests in the elderly

This study aimed to determine and evaluate the diagnostic accuracy of visual screening tests for detecting vision loss in elderly. This study is defined as study of diagnostic performance. The diagnostic accuracy of 5 visual tests -near convergence point, near accommodation point, stereopsis, contrast sensibility and amsler grid—was evaluated by means of the ROC method (receiver operating characteristics curves), sensitivity, specificity, positive and negative likelihood ratios (LR+/LR−). Visual acuity was used as the reference standard. A sample of 44 elderly aged 76.7 years (±9.32), who were institutionalized, was collected. The curves of contrast sensitivity and stereopsis are the most accurate (area under the curves were 0.814−p = 0.001, C.I.95%[0.653;0.975]— and 0.713−p = 0.027, C.I.95%[0,540;0,887], respectively). The scores with the best diagnostic validity for the stereopsis test were 0.605 (sensitivity 0.87, specificity 0.54; LR+ 1.89, LR−0.24) and 0.610 (sensitivity 0.81, specificity 0.54; LR+1.75, LR−0.36). The scores with higher diagnostic validity for the contrast sensibility test were 0.530 (sensitivity 0.94, specificity 0.69; LR+ 3.04, LR−0.09). The contrast sensitivity and stereopsis test's proved to be clinically useful in detecting vision loss in the elderly.

Diagnostic performance of visual screening tests in the elderly

The aging of Portuguese population is characterized by an increase of individuals aged older than 65 years. Preventable visual loss in older persons is an important public health problem. Tests used for vision screening should have a high degree of diagnostic validity confirmed by means of clinical trials. The primary aim of a screening program is the early detection of visual diseases. Between 20% and 50% of older people in the UK have undetected reduced vision and in most cases is correctable. Elderly patients do not receive a systematic eye examination unless a problem arises with their glasses or suspicion vision loss. This study aimed to determine and evaluate the diagnostic accuracy of visual screening tests for detecting vision loss in elderly. Furthermore, it pretends to define the ability to find the subjects affected with vision loss as positive and the subjects not affected with the same disease as negative. The ideal vision screening method should have high sensitivity and specificity for early detection of risk factors. It should be also low cost and easy to implement in all geographic and socioeconomic regions. Sensitivity is the ability of an examination to identify the presence of a given disease and specificity is the ability of the examination to identify the absence of a given disease. It was not an aim of this study to detect abnormalities that affect visual acuity. The aim of this study was to find out what´s the best test for the identification of any vision loss.

Risk factors for non compliance using occlusive therapy: a case study

Purpose: compliance with treatment is a common problem when treating amblyopic patients. Visual acuity of amblyopic eye does not improve without effective occlusive therapy. The aim of this study is to identify potential risk factors of non-compliance with treatment when it is implemented by family in amblyopic children. Setting: a quantitative transversal study was performed in a public hospital and in a private clinic in Lisbon.

Tuning Iris Recognition for Noisy Images

The use of iris recognition for human authentication has been spreading in the past years. Daugman has proposed a method for iris recognition, composed by four stages: segmentation, normalization, feature extraction, and matching. In this paper we propose some modifications and extensions to Daugman's method to cope with noisy images. These modifications are proposed after a study of images of CASIA and UBIRIS databases. The major modification is on the computationally demanding segmentation stage, for which we propose a faster and equally accurate template matching approach. The extensions on the algorithm address the important issue of pre-processing that depends on the image database, being mandatory when we have a non infra-red camera, like a typical WebCam. For this scenario, we propose methods for reflection removal and pupil enhancement and isolation. The tests, carried out by our C# application on grayscale CASIA and UBIRIS images show that the template matching segmentation method is more accurate and faster than the previous one, for noisy images. The proposed algorithms are found to be efficient and necessary when we deal with non infra-red images and non uniform illumination.

MDAI: Model based Design in Automobile Industry

It is proposed a new approach based on a methodology, assisted by a tool, to create new products in the automobile industry based on previous defined processes and experiences inspired on a set of best practices or principles: it is based on high-level models or specifications; it is component-based architecture centric; it is based on generative programming techniques. This approach follows in essence the MDA (Model Driven Architecture) philosophy with some specific characteristics. We propose a repository that keeps related information, such as models, applications, design information, generated artifacts and even information concerning the development process itself (e.g., generation steps, tests and integration milestones). Generically, this methodology receives the users' requirements to a new product (e.g., functional, non-functional, product specification) as its main inputs and produces a set of artifacts (e.g., design parts, process validation output) as its main output, that will be integrated in the engineer design tool (e.g. CAD system) facilitating the work.

Non-selective optical wavelength-division multiplexing devices based on a-SiC:H multilayer heterostuctures

In this paper we present results on the optimization of multilayered a-SiC:H heterostructures for wavelength-division (de) multiplexing applications. The non selective WDM device is a double heterostructure in a glass/ITO/a-SiC:H (p-i-n) /a-SiC:H(-p) /a-Si:H(-i')/a-SiC:H (-n')/ITO configuration. The single or the multiple modulated wavelength channels are passed through the device, and absorbed accordingly to its wavelength, giving rise to a time dependent wavelength electrical field modulation across it. The effect of single or multiple input signals is converted to an electrical signal to regain the information (wavelength, intensity and frequency) of the incoming photogenerated carriers. Here, the (de) multiplexing of the channels is accomplished electronically, not optically. This approach offers advantages in terms of cost since several channels share the same optical components; and the electrical components are typically less expensive than the optical ones. An electrical model gives insight into the device operation.

Surge damping analysis in pipe systems: modelling and experiments

The current study focuses on the analysis of pressure surge damping in single pipeline systems generated by a fast change of flow, conditions. A dimensionless form of pressurised transient flow equations was developed. presenting the main advantage of being independent of the system characteristics. In lack of flow velocity profiles. the unsteady friction in turbulent regimes is analysed based on two new empirical corrective-coefficients associated with local and convective acceleration terms. A new, surge damping approach is also presented taking into account the pressure peak time variation. The observed attenuation effect in the pressure wave for high deformable pipe materials can be described by a combination of the non-elastic behaviour of the pipe-wall with steady and unsteady friction effects. Several simulations and experimental tests have been carried out. in order to analyse the dynamic response of single pipelines with different characteristics, such as pipe materials. diameters. thickness. lengths and transient conditions.

A non-pixel image reader for continuous image detection based on tandem heterostructures

An optically addressed read-write sensor based on two stacked p-i-n heterojunctions is analyzed. The device is a two terminal image sensing structure. The charge packets are injected optically into the p-i-n writer and confined at the illuminated regions changing locally the electrical field profile across the p-i-n reader. An optical scanner is used for charge readout. The design allows a continuous readout without the need for pixel-level patterning. The role of light pattern and scanner wavelengths on the readout parameters is analyzed. The optical-to-electrical transfer characteristics show high quantum efficiency, broad spectral response, and reciprocity between light and image signal. A numerical simulation supports the imaging process. A black and white image is acquired with a resolution around 20 mum showing the potentiality of these devices for imaging applications.

Stacked photo-sensing devices based on SiC alloys A non-pixelled architecture for imagers and demultiplexing devices

In this review paper different designs based on stacked p-i'-n-p-i-n heterojunctions are presented and compared with the single p-i-n sensing structures. The imagers utilise self-field induced depletion layers for light detection and a modulated laser beam for sequential readout. The effect of the sensing element structure, cell configurations (single or tandem), and light source properties (intensity and wavelength) are correlated with the sensor output characteristics (light-to-dark sensivity, spatial resolution, linearity and S/N ratio). The readout frequency is optimized showing that scans speeds up to 104 lines per second can be achieved without degradation in the resolution. Multilayered p-i'-n-p-i-n heterostructures can also be used as wavelength-division multiplexing /demultiplexing devices in the visible range. Here the sensor element faces the modulated light from different input colour channels, each one with a specific wavelength and bit rate. By reading out the photocurrent at appropriated applied bias, the information is multiplexed or demultiplexed and can be transmitted or recovered again. Electrical models are present to support the sensing methodologies.

A comparative study of alternative approaches for common factors identification

Preliminary version

A model to forecast financial failure, in non financial galician SMES

We are concerned with providing more empirical evidence on forecast failure, developing forecast models, and examining the impact of events such as audit reports. A joint consideration of classic financial ratios and relevant external indicators leads us to build a basic prediction model focused in non-financial Galician SMEs. Explanatory variables are relevant financial indicators from the viewpoint of the financial logic and financial failure theory. The paper explores three mathematical models: discriminant analysis, Logit, and linear multivariate regression. We conclude that, even though they both offer high explanatory and predictive abilities, Logit and MDA models should be used and interpreted jointly.

Placas de OSB: investigação e estudo laboratorial das suas características de desempenho

A utilização de placas de OSB – Oriented Strand Board está em franca expansão no território nacional e parece ser uma alternativa ecológica e económica aos painéis de derivados de madeira normalmente usados. O OSB é obtido num processo de fabrico resultante da interacção de diversas variáveis, que conferem aos painéis uma vasta gama de aplicações estruturais ou não estruturais (paredes exteriores e interiores, pavimentos, coberturas, componentes de vigas, cofragens, embalagens, móveis, elementos de decoração, etc.). Neste trabalho pretendeu-se investigar, através de pesquisa bibliográfica as características das placas OSB assim como seu processo de fabrico e condicionantes existentes no seu decurso. Em seguida estas foram comparadas com os seus principais concorrentes, o contraplacado e o aglomerado de madeira e cimento. O trabalho experimental realizado teve como objectivo analisar as propriedades de OSB, proveniente do mercado nacional, de acordo com a EN 300:2006 e com os dados recolhidos na pesquisa bibliográfica. Foram executados ensaios de flexão (EN 310:2002), inchamento em espessura (EN 317:2002) e ensaios de flexão após envelhecimento (EN 321:2010). Concluiu-se que o OSB é um material com algumas características de destaque, no entanto a substituição de outros derivados de madeira por este deve ser acompanhada por estudos, principalmente em ambientes húmidos. É importante realçar que este possui modelos com características específicas para determinadas utilizações e ambientes que possibilitam uma optimização do seu comportamento, no entanto, nos ensaios realizados apenas foi utilizado um modelo base de OSB.

Efeito da incorporação de resíduos da indústria petrolífera na durabilidade de argamassas de reparação de estruturas de betão

Na presente dissertação, o trabalho desenvolvido teve como objetivo, a avaliação de alguns parâmetros de durabilidade de argamassas com incorporação de catalisador exausto de FCC (do inglês “Fluid Catalytic Cracking”) para serem utilizadas na reparação de estruturas de betão. O catalisador exausto de FCC é um resíduo da indústria petrolífera e o utilizado neste estudo é proveniente da refinaria da Petrogal, S.A. em Sines. A presente investigação baseou-se na preparação, e avaliação de propriedades, de duas séries distintas de argamassas: a série que se denominou “RAS” e a série que se denominou “Durabilidade”, nas quais se substituiu, parcialmente entre 5, 10 e 15%, em massa de cimento por resíduo exausto de FCC. As argamassas de ambas as séries diferenciam-se entre si, sobretudo, pela utilização de areia reativa nas argamassas da série RAS e de areia inerte no caso das argamassas da série durabilidade. Nas argamassas estudadas foram realizados ensaios no estado fresco e ensaios no estado endurecido. Os ensaios no estado fresco incluíram a determinação da consistência por espalhamento, da massa volúmica e do teor de ar. Nos ensaios no estado endurecido foram avaliadas, no caso das argamassas da série RAS a extensão da reação àlcalis-sílica e no caso das argamassas da série Durabilidade as resistências mecânicas - à flexão e à compressão, a resistência à carbonatação acelerada, o módulo de elasticidade à compressão, a absorção capilar, a permeabilidade ao oxigénio, a difusão de cloretos em regime não estacionário. O trabalho desenvolvido nesta dissertação demonstrou que a incorporação de catalisador exausto de FCC, em argamassas à base de cimento, minimiza o efeito de expansão das reações álcalis-sílica, bem como contribui para reduzir a absorção capilar e coeficiente de difusão de cloretos. No entanto, este resíduo quando incorporados em argamassas contribui para a diminuição da resistência à carbonatação acelerada e para o aumento da permeabilidade ao oxigénio.

Symbolic dynamics and renormalization of non-autonomous k periodic dynamical systems

The purpose of this paper was to introduce the symbolic formalism based on kneading theory, which allows us to study the renormalization of non-autonomous periodic dynamical systems.