Micro-EDXRF, SEM-EDS and OM characterisation of tin soldering found in handle attachments of Roman situlae from Conimbriga (Portugal)

Tin (Sn) or a Sn-rich solder applied to copper-based artefacts has been frequently used at least, since the Ancient Greece, although scarce studies have been published concerning the technology of this metallurgical joining technique. Several filler remnants were reported to be found in a Roman collection of handle attachments of situlae or cauldrons (2nd century BCE–5th century CE) from the archaeological site of Conimbriga, a Roman city from the Lusitania Province (Portugal). All these artefacts were cast in high leaded coppers and bronzes. The present study aims to contribute to the knowledge of Sn-rich soldering, an ancientmetallurgical joining technique, by the characterisation of the fusible metallic alloy present in 10 Roman artefacts by means of micro-energy dispersive X-ray fluorescence spectrometry (micro-EDXRF), scanning electron microscopy with energy dispersive X-ray (SEM-EDS) microanalysis and optical microscope (OM) observations. Results of studied solders show the presence of Cu-Sn alloys, with Sn contents ranging from δ to η phase composition (30–60wt% Sn). As the attachments were made in leaded copper alloys, it was also observed, in some cases, the melting of the interdendritic Pb-rich chains with long-range diffusion of the solder alloy into the substrate. The fillers compositions suggest that the handle attachments have been joined to a situla body by the soldering metallurgical process with Sn or a Sn-rich alloy. The studied leaded Cu-Sn attachments, probably formulated by local craftsman, were joined into the body of a situla or cauldron with a soft solder (soldering), a common metallurgical joint from Antiquity, although no relation was found between composition or typology and the Sn or Sn-rich solder

Slowly Rotating Anisotropic Neutron Stars in General Relativity and Scalar-Tensor Theory

Some models (such as the Skyrme model, a low-energy effective field theory for QCD) suggest that the high-density matter prevailing in neutron star interiors may be significantly anisotropic. Anisotropy is known to affect the bulk properties of nonrotating neutron stars in General Relativity. In this paper we study the effects of anisotropy on slowly rotating stars in General Relativity. We also consider one of the most popular extensions of Einstein's theory, namely scalar-tensor theories allowing for spontaneous scalarization (a phase transition similar to spontaneous magnetization in ferromagnetic materials). Anisotropy affects the moment of inertia of neutron stars (a quantity that could potentially be measured in binary pulsar systems) in both theories. We find that the effects of scalarization increase (decrease) when the tangential pressure is bigger (smaller) than the radial pressure, and we present a simple criterion to determine the onset of scalarization by linearizing the scalar-field equation. Our calculations suggest that binary pulsar observations may constrain the degree of anisotropy or even, more optimistically, provide evidence for anisotropy in neutron star cores.Comment: 19 pages, 7 figures, 1 table. Matches version in press in CQG. Fixed small typo

The role performed by the teacher’s question in the learning of quadratic function in an exploratory mathem

Communication plays a key role in teaching and learning processes. Questions are a communicational act greatly used by teachers to structure their discourse, establish dynamics, and foster interaction between the different participants in the classroom. In view of these potentialities of questions in the classroom context, we have developed a teaching experiment with the aim of understand the role of the teacher's question in the learning of topics on functions. Considering the nature of this aim, a methodology of qualitative and interpretative nature was used. The data collection was based on the students’ written productions and on the audio and video recordings of a mathematics class of a Grade 10 educational group (in northern Portugal). Data analysis is based on content analysis techniques, crossing collected data and categories emerging from the literature. The study revealed that the teacher’s questions alternated between confirmation, focalization, and inquiry, with inquiry prevailing. Questions aimed at testing the student’s knowledge gave both the teacher and actual student important information. Questions that focused the student’s attention on a particular detail enabled the students to organize their reasoning and structure their answer. Questions that required the students to explain or justify their thoughts were those that proved to most contribute to the development of the student’s reasoning process.info:eu-repo/semantics/publishedVersio

Modelica como uma linguagem de engenharia: modelação de sistemas mecânicos/mecatrónicos

No presente artigo vão ser abordados alguns exemplos mecânicos/mecatrónicos básicos que podem ser encontrados nas bibliotecas do software Dymola 6.0 ou criados pelos autores, no sentido de serem verificadas as potencialidades do mesmo para a sua aplicação no projeto de sistemas/produtos.info:eu-repo/semantics/publishedVersio

O projeto DACHOR: Dinâmica multicorpo e controlo de ortóteses híbridas activas

Fundação para a Ciência e a Tecnologia pelo financiamento concedido no âmbito do projecto MIT-PVBSHHMS/0042/200

Machine and mechanism design at UMinho: research-teaching interaction

Publicado em: "New trends in mechanism and machine science: from fundamentals to industrial applications. ISBN 978-3-319-09410-6. Series: Mechanisms and machine science, vol. 24, ISSN 2211-0984"The Multiweave project involved the design of a prototype machine with several mecha-nisms, namely gear trains and various conjugate cams with oscillating roller followers. For this design phase the research team integrated postgraduate student work. In order to evaluate the quality of the manufactured cam profiles as well as the accuracy of the follower’s displacement, an experimental work has been designed. This study, which was carried out within a final year Mechanical Engineering student’s group project, was of great importance in the development of the prototype machine to pro-duce multidirectional woven fabrics, which was the main objective of the Multiweave project. The whole set-up is presented with the experimental details and the results are analysed and discussed. This measurement system is based on a laser triangulation sensor Micro-Epsilon ILD 1302-50 to measure with no contact and high resolution. The obtained results were compared with the expected theoretical values and it could be concluded that, in general, the experimental results adjust very well to the theo-retical ones. However it was possible to conclude about the existence of some differences due to clear-ances in joints, geometric differences in the kinematic chain and manufacturing defects on the follower in terms of irregularities and surface roughness as well as some manufacturing imperfections of the cam surface

Improving feeding efficiency of a sewing machine by on-line control of the presser foot

This paper presents a contribution towards the development of a new generation of sewing equipment integrating auxiliary add-on kits to improve performance and flexibility in the production of high-quality garments. An overview of all the recent developments concerning the redesign of the first PC-based controller developed for a novel electromagnetically actuated presser foot on an industrial overlock sewing machine will be presented. Other software modules, developed to ease the establishment of control references and the tuning of the controller parameters, as well as a brief discussion and analysis of the obtained results, will also be described in this paper. According to the latest results here reported, the presser foot firmly controls the fabric plies for a wide range of materials and situations

Estudo e conceção de um sistema de encaixe rápido e simples para próteses de membros inferiores

A variedade dos sistemas de suspensão, ou sistemas de encaixe, entre o membro residual e a prótese passam por mecanismos de pino de bloqueio, vácuo, sucção, magnéticos e híbridos. Cada tipo de mecanismo apresenta um conjunto de vantagens e desvantagens que o torna mais adequado para determinados tipos de situações. Contudo, o descontentamento demonstrado por parte dos pacientes amputados em relação às suspensões utilizadas incide principalmente na dificuldade em estabelecer uma boa suspensão, quer pela pouca destreza manual demonstrada pelo paciente, quer pela dificuldade de montagem do próprio mecanismo [1]. Surge assim a necessidade para o estudo e a conceção de um novo sistema de encaixe. No estudo realizado foram utilizadas várias ferramentas de auxílio ao projeto (como a árvore de objetivos, o diagrama de funções, o mapa morfológico) que permitiram a obtenção de diferentes soluções alternativas, de entre as quais foi selecionada uma que apresenta um sistema de encaixe que proporciona uma ligação rápida, simples e ergonómica.info:eu-repo/semantics/publishedVersio

POLQUAL : measuring service quality in police traffic services

Purpose The purpose of this paper is to build a customer quality assessment scale for use in the field of policing – POLQUAL. It adapts and applies a modified SERVQUAL approach to police traffic services in Portugal. Design/methodology/approach Original data was collected by means of telephone interviews over a three‐month period. The proposed scale's reliability and validity are assessed. Findings The study shows how it is possible to implement a SERVQUAL‐based approach in police traffic services. The adapted scale – POLQUAL – includes all five original dimensions plus another new dimension “promptitude”. The most negative gaps found are for the dimensions of reliability and tangibles. There was evidence that perceived quality of service decreases as the level of education of the driver increases. The paper did not find a difference between perceived quality of service provided between requested services and imposed services, respectively, represented by the accident service and radar service. Research limitations/implications The results are based on a specific police services context – that of out of office traffic services in Portugal. Practical implications The study provides the police traffic services with a tool for measuring quality of service which can provide information for focusing improvement efforts. Social implications Often the user cannot choose to interact with police services. However, in a democratic society good quality of service is essential for maintaining trust in the police services. Originality/value The study provides police traffic services with a valid and reliable tool to assess quality of service from the user's perspective.info:eu-repo/semantics/publishedVersio

Design and development of a feeding aid device to assist people with deficiency

The present work intends to design new devices of aid to the feeding for individuals with deficiency. Like this, along this paper they are referred the most relevant pathologies, which affect the autonomy of the patient’s feeding, as well as some existent devices in the market. Based on the characteristics of these devices, this research was performed with the main objective of finding the most appropriate actuation system. Furthermore, it was made the analysis and discussion of the performance specifications, essential stage in the design process of the feeding aid device for this to assure all the demanded requirements. Afterward, they are pointed some possible solutions, in the sense of creating more and better on behalf of the patient's need. Finally, for the solution selected, it was being later developed a model, in the advanced software Working Model for the simulation of the mechanical system of aid feeding