Nuno Dourado

A study on the dynamics of a study on the dynamics of spatial mechanisms with frictional spherical clearance joints

The first author expresses his gratitude to the Portuguese Foundation for Science and Technology through the PhD grant (PD/BD/114154/2016). This work has been supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalizacao (POCI) with the reference project POCI-01-0145-FEDER-006941.

3D Formulation for Revolute Clearance Joints

In this work, a general and comprehensive methodology for the modeling and analysis of spatial multibody systems with revolute clearance joints is presented. The proposed formulation considers the journal and the bearing elements as two cylindrical colliding bodies. All the potential contact scenarios and their kinematics are determined from the relative positions of two cylinders and from the kinematics of the multibody systems. It must be highlighted that both radial and axial clearances are modeled under the new proposed approach. The methodology presented here is demonstrated by using a spatial slider-crank mechanism that incorporates a spatial revolute clearance joint. The results show that the system’s response is considerably influenced by the existence of a clearance joint.

Recent Developments on Cylindrical Contact Force Models with Realistic Properties

In this work a numerical study was performed involving a spatial revolute joint formed by a journal and a bearing with the purpose to evaluate the effect of the bearing thickness, misalignment and impact velocity on the force generated in the contact process. These analyses were run in a developed three-dimensional finite element model that simulates the referred aspects in a realistic way. This numerical tool allows defining both radial and axial clearances, which are important aspects in the analysis of operating conditions of actual journal-bearing joints. Resulting forces and stress profiles were calculated in different regions of the model, contributing to the accurate definition of design parameters. The generated data was ultimately compared and validated with the one obtained from the models that are currently used in the context of multibody dynamics and predict kinematic aspects of mechanical systems involving cylindrical contact interaction.

Bone turnover markers in sheep and goat: A review of the scientific literature

Bone turnover markers (BTMs) are product of bone cell activity and are generally divided in bone formation and bone resorption markers. The purpose of this review was to structure the available information on the use of BTMs in studies on small ruminants, especially for monitoring their variations related to diet, exercise, gestation and metabolic lactation state, circadian and seasonal variations, and also during skeletal growth. Pre-clinical and translational studies using BTMs with sheep and goats as animal models in orthopaedic research studies to help in the evaluation of the fracture healing process and osteoporosis research are also described in this review. The available information from the reviewed studies was systematically organized in order to highlight the most promising BTMs in small ruminant research, as well as provide a wide view of the use of sheep and goat as animal models in orthopaedic research, type of markers and commercial assay kits with cross-reactivity in sheep and goat, method of sample and storage of serum and urine for bone turnover markers determination and the usefulness and limitations of bone turnover markers in the different studies, therefore an effective tool for researchers that seek answers to different questions while using BTMs in small ruminants.

A study on the dynamics of spatial mechanisms with frictional spherical clearance joints

The first author expresses his gratitude to the Portuguese Foundation for Science and Technology through the PhD grant (PD/BD/114154/2016). This work has been supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 - Programa Operacional Competitividade e Internacionalizacao (POCI) with the reference project POCI-01-0145-FEDER-006941

Undergraduates’ Views of Assessment in Higher Education: A Study carried out in Portugal

This paper looks at how undergraduates look at assessment in Higher Education. It focuses on their views about assessment practices in five Portuguese public universities. The main purpose is to look at the students’ perceptions of assessment in higher education taking into account the assessment methods used, the influence of assessment in their motivation to learn as well as self-regulation of the learning process. Data were collected through questionnaires in five Portuguese Public Universities in different fields of knowledge. An intervention project focused on Assessment for Learning (AfL), with students enrolled at an Engineering programme, in one public university in Portugal, in one course with student-centred methodologies and AfL practices was also carried out and evaluated. Preliminary findings are presented according the categories emerging from the data. Issues of assessment methods, the connection between teaching, learning and assessment as well as the impact of AfL environments on students’ perceptions are analysed. Implications of the findings for assessment, teaching and learning process are discussed.