3,311 research outputs found

    Mobi algebra as an abstraction to the unit interval and its comparison to rings

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    We introduce a new algebraic structure, called mobi algebra, consisting of three constants and one ternary operation. The canonical example of a mobi algebra is the unit interval with the three constants 0, 1, and 1/2 and the ternary operation given by the formula x−yx+yz. We study some of its properties and prove that every unitary ring with one half uniquely determines and is uniquely determined by a mobi algebra with one double. Another algebraic structure, called involutive medial monoid (IMM), is considered to establish the passage between rings and mobi algebras.info:eu-repo/semantics/publishedVersio

    Testing Λ\Lambda-Free f(Q) Cosmology

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    We study a model of Symmetric Teleparallel gravity that is able to account for the current accelerated expansion of the universe without the need for dark energy component. We investigate this model by making use of dynamical system analysis techniques to identify the regions of the parameter space with viable cosmologies and constrain it using type Ia supernova (SnIa), cosmic microwave background (CMB) data and make forecasts using standard siren (SS) events. We conclude that this model is disfavored with respect to Λ\LambdaCDM and forthcoming standard siren events can be decisive in testing the viability of the model.Comment: 9 pages, 3 figure

    Damage localization on CFRP composites by electrical impedance tomography

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    This work exploited the use of electrical impedance tomography (EIT) with one-step difference Gaussian-Newton (GN) algorithm to detect different types of damage on unidirectional carbon fibre/epoxy composite laminates. The major challenge concerning the implementation of EIT on composite materials has to do with their anisotropy. To assess this issue, this study was conducted on carbon fibre composites having different layup configurations with different degrees of anisotropy: a quasi-isotropic layup, to approximate as much as possible these layered materials to an isotropic material, and an unbalanced layup, with further degree of anisotropy. Damage detection in the highly anisotropic unbalanced laminates is a major challenge for EIT technique, which has not been assessed before in the literature. Severe damage, in the form of through-thickness holes, was created in the laminates with different diameters and at two locations of the specimen to evaluate the sensitivity of this technique to damage size and its capacity to detect multiple damages. EIT showed progressive decrease of electrical conductivity as the diameter of through-thickness holes increased. Impact damages of different severities were also created. The EIT technique was able to distinguish different damage shapes in the laminates with different anisotropy. EIT identified elongated shaped damages, produced by impact events of different impact energies, on unbalanced laminates. However, the EIT images overestimate the damaged area, as compared to non-destructive ultrasonic inspections. The EIT images of the quasi-isotropic laminates revealed damage in the central area of the specimens, but a well-defined damage shape could not be distinguished.ANI, H2020, Contrato NORTE-01-0145-FEDER-00001

    Electrical impedance tomography for damage detection and localization on carbon fibre reinforced polymer composites

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    Electrical impedance tomography (EIT) is being developed as promising non-intrusive technology for damage detection in conductive fibre reinforced polymers (FRP) composites. This work assessed EIT and one-step difference Gaussian-Newton algorithm to detect different damages in CFRP laminates, including through-thickness holes and impact damage of different severities. Two layup laminates were studied: quasi-isotropic [0/45/90/-45]s and unbalanced [0/0/45/90/-45]s. Each laminate configuration was subjected to three levels of impact energy.Through-thickness holes with diameters as small as 2 mm were detected. The LVI on unbalanced specimens created elongated shaped damages, which were observed through EIT and ultrasonic C-scan. Differently, the ultrasonic C-scan inspections revealed circular shaped damages on the centre of the quasi-isotropic specimens, while EIT could not reveal a well-defined damage shape Yet, the presence of damage was observed in the centre of the specimens by EIT. Although EIT overestimated the damaged area, it was highly sensitive to the imposed damages.The authors would like to acknowledge the support of the European Regional Development Fund [grant number NORTE-01-0145-FEDER-000015]; and of the European Space Agency [Network/Partnering Initiative Program - ESA Contract 4000123315]

    Biodegradation of textile azo dyes by Phanerochaete chrysosporium

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    Instituto de Biotecnologia e Química Fina / Universidade do Minho (IBQF/UM) - Praxis XXI, Praxis XXI 2/2.1/QUI/44/94, Praxis XXI/BD/9120/96

    Penetrating Ureteral Trauma.

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    The purpose of this series is to report our experience in managing ureteral trauma, focusing on the importance of early diagnosis, correct treatment, and the impact of associated injuries on the management and morbid-mortality. From January 1994 to December 2002, 1487 laparotomies for abdominal trauma were performed and 20 patients with ureteral lesions were identified, all of them secondary to penetrating injury. Medical charts were analyzed as well as information about trauma mechanisms, diagnostic routine, treatment and outcome. All patients were men. Mean age was 27 years. The mechanisms of injury were gunshot wounds in 18 cases (90%) and stab wounds in two (10%). All penetrating abdominal injuries had primary indication of laparotomy, and neither excretory urography nor computed tomography were used in any case before surgery. The diagnosis of ureteric injury was made intra-operatively in 17 cases (85%). Two ureteral injuries (10%) were initially missed. All patients had associated injuries. The treatment was dictated by the location, extension and time necessary to identify the injury. The overall incidence of complications was 55%. The presence of shock on admission, delayed diagnosis, Abdominal Trauma Index > 25, Injury Severity Score > 25 and colon injuries were associated to a high complication rate, however, there was no statistically significant difference. There were no mortalities in this group. A high index of suspicion is required for diagnosis of ureteral injuries. A thorough exploration of all retroperitoneal hematoma after penetrating trauma should be an accurate method of diagnosis; even though it failed in 10% of our cases.33142-8, discussion 149-5

    Biodegradation of bioaccessible textile azo dyes by Phanerochaete chrysosporium

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    Azo dyes are important chemical pollutants of industrial origin. Textile azo dyes with bioaccessible groups for lignin degrading fungi, such as 2-methoxyphenol (guaiacol) and 2,6-dimethoxyphenol (syringol), were synthesised using different aminobenzoic and aminosulphonic acids as diazo components. The inocula of the best biodegradation assays were obtained from a pre-growth medium (PAM), containing one of the synthesised dyes. The results of the dye biodegradation assays were evaluated every 7 days, by the decrease of the absorbance at the maximum wavelength of the dye, by the decrease of the sucrose concentration in the culture medium and by the increase of the biomass during the 28 days of assay. It was observed that the extent of dye biodegradation depended on the sucrose concentration, on the degraded dye structure and, on the dye present in the PAM medium.Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI/BD/15878/98, PRAXIS XXI/BD/9120/96.Instituto de Biotecnologia e Química Fina (IBQF)

    Estudos de biodegradabilidade de corantes azo de aplicação têxtil por Phanerochaete chrysosporium

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    Sintetizaram-se corantes azo de aplicação têxtil, usando como componentes diazo ácidos aminobenzóicos e aminossulfónicos e como componentes de acoplamento 2- metoxifenol e 2,6-dimetoxifenol. A utilização destas componentes de acoplamento teve como objectivo aumentar a bioacessibilidade dos corantes ao fungo lenhinolítico da podridão branca Phanerochaete chrysosporium, já que estes grupos estão presentes na estrutura da lenhina e têm sido referidos como pontos de acesso para o sistema enzimático lenhinolítico do fungo. As experiências de biodegradação realizaram-se em meio líquido, com sacarose e em condições limitantes de azoto, com agitação e temperatura controladas. A biodegradação dos corantes foi acompanhada por espectrofotometria UV-Visível, quantificando a diminuição da intensidade da banda de absorção máxima (λmax) do corante. Em estudos preliminares estabeleceram-se condições experimentais optimizadas relativamente ao meio de préadaptação e à concentração de sacarose utilizada. Estabeleceram-se algumas correlações entre a estrutura química dos corantes e a sua biodegradação.Praxis XX
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