A map for heavy inertial particles in fluid flows

We introduce a map which reproduces qualitatively many fundamental properties of the dynamics of heavy particles in fluid flows. These include a uniform rate of decrease of volume in phase space, a slow-manifold effective dynamics when the single parameter $s$ (analogous of the Stokes number) approaches zero, the possibility of fold caustics in the "velocity field", and a minimum, as a function of $s$, of the Lyapunov (Kaplan-Yorke) dimension of the attractor where particles accumulate.Comment: 10 pages, 5 figure

Learning to Race through Coordinate Descent Bayesian Optimisation

In the automation of many kinds of processes, the observable outcome can often be described as the combined effect of an entire sequence of actions, or controls, applied throughout its execution. In these cases, strategies to optimise control policies for individual stages of the process might not be applicable, and instead the whole policy might have to be optimised at once. On the other hand, the cost to evaluate the policy's performance might also be high, being desirable that a solution can be found with as few interactions as possible with the real system. We consider the problem of optimising control policies to allow a robot to complete a given race track within a minimum amount of time. We assume that the robot has no prior information about the track or its own dynamical model, just an initial valid driving example. Localisation is only applied to monitor the robot and to provide an indication of its position along the track's centre axis. We propose a method for finding a policy that minimises the time per lap while keeping the vehicle on the track using a Bayesian optimisation (BO) approach over a reproducing kernel Hilbert space. We apply an algorithm to search more efficiently over high-dimensional policy-parameter spaces with BO, by iterating over each dimension individually, in a sequential coordinate descent-like scheme. Experiments demonstrate the performance of the algorithm against other methods in a simulated car racing environment.Comment: Accepted as conference paper for the 2018 IEEE International Conference on Robotics and Automation (ICRA

Quality Assurance System to monitor the teaching and learning process at the University of Aveiro (Portugal)

At the University of Aveiro (UA), in Portugal, institutional initiatives are being undertaken so that high levels of quality teaching and learning are achieved. This paper presents (a) the design of an evaluation model for quality assurance of teaching and learning and (b) the results of its application in a pilot study that ran in 2008/09 at the Departments of Electronics and Telecommunications, and Physics, of the UA. The Quality Assurance System (QAS) to monitor the process of teaching and learning at the UA emerges as extremely important, not only to regulate the teaching and learning process, following the quality assurance orientations at a national and international level, but also to reflect and share teaching practices that enhance the whole academic experience, both from students, teachers, and researchers‟ perspectives. The authors explore the design of the model and some findings of the pilot study, more specifically the identification of problematic and good practice situations identified by the students‟ survey and reports

Linking educational research to institutional measures of quality enhancement: a Portuguese project

At the University of Aveiro (UA), an institutional initiative is taking place for assessing and monitoring the quality of teaching and learning in Higher Education. The Quality Assurance System (QAS) of the teaching and learning process at the UA emerges as extremely important, not only to regulate the teaching and learning process, following the quality assurance orientations at a national and international level, but also to reflect and share teaching practices that enhance the whole academic experience, both from the students, the teachers, and researchers’ perspective. The authors explore the design of the model and a research study that aims to integrate the perspectives of students and teachers, through the analysis of quantitative and qualitative data - gathered in the evaluation model, so that: (i) intervention strategies/activities can be conceptualised for coping with the identified problems; (ii) a set of guidelines can be designed for the improvement of the evaluation model and associated instruments, and (iii) the QAS model and its results can be discussed with academia in terms of strengths and weaknesses aiming to engage them in the process of monitoring. This study is an effort to conciliate the educational research carried out by members of the Laboratory for the Evaluation of Educational Quality and the institutional framework for quality assurance

Engineering of extracellular matrix-like biomaterials at nano- and macroscale toward fabrication of hierarchical scaffolds for bone tissue engineering

The increasing rate of musculoskeletal pathologies has compelled the development of improved and novel treatment strategies in order to address unmet clinical needs. Tissue engineering approaches comprising the use of scaffolds for bone regeneration have been showing to be a promising alternative to conventional bone repair/substitution approaches. In particular, hierarchical scaffolds as methods of structural support and osteogenic differentiation promoters are among the most used tools in bone tissue engineering (BTE). In this reasoning, hierarchical scaffolds have sparked the field, striving toward mimicking the natural bone tissue in both, its complex 3D structure and composition. A recent and promising trend has been the merging of nanotechnology and tissue engineering concepts. As such the incorporation of nanoparticles and nanocomposites into micro- or macroscaffold systems can result in an improvement of scaffoldsâ biofunctionality at different levels. These tools are versatile in nature and can be used for multiple purposes such as drug delivery, thermal conductors, and mechanical reinforcement. Taking into consideration multidisciplinary approaches, several strategies have been pursued. The recent reports dealing with the approaches pursued in the hierarchical scaffolds production and enhancement, ranging from the nanoscale to the macroscale, are overviewed herein.The authors thank the funds provided by the project FROnTHERA (NORTE-01-0145-FEDER-000023), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), the project 3BioMeD (FCT/4773/ 4/5/2017/S) supported by Fundação para a Ciência e a Tecnologia (FCT) and the R&D Project KOAT PTDC/BTMMAT/29760/2017 (POCI 01-0145-FEDER-029760) financed by FCT and cofinanced by FEDER and POCI. F.R.M. acknowledges FCT for her contract under the Transitional Rule DL 57/2016 (CTTI-57/18-I3BS (5))

Gastrointestinal Tuberculosis Mimicking Crohn’s Disease

We present the case of a 24-year-old woman with complaints of abdominal pain, bloody diarrhea, and weight loss for 3 months. An outpatient colonoscopy revealed scattered ulcers, suggestive of Crohn's disease (CD). Histopathology also favored the diagnosis of CD. However, after admission to our hospital for further investigation, a chest radiograph revealed pulmonary cavitations. A computed tomography scan suggested the diagnosis of active pulmonary tuberculosis (TB). Therefore, a bronchofibroscopy, a total colonoscopy with ileoscopy, and an upper endoscopy were performed. Not only were acid-fast bacilli present in both bronchoalveolar lavage fluid and gastric juice, but also in colonic biopsies. A complete resolution of gastrointestinal symptoms was achieved 2 weeks after starting anti-TB drugs.info:eu-repo/semantics/publishedVersio

Irreversible time-dependent rheological behavior of cement slurries : constitutive model and experiments

Over the last few decades, much focus has been given to investigating the reversible rheological behavior of thixotropic materials, but the description of the rheology of materials undergoing an irreversible process is still challenging. In this work, the time-dependent rheological behavior of a cement slurry is investigated. Different rheometric experiments are performed to evaluate the structure breakdown under shear, cement gelation, and curing process. A recently proposed thixotropic elasto-viscoplastic model [de Souza Mendes, Soft Matter 7, 2471-2483 (2011)] is modified to account for irreversible effects, which can be either of a chemical or physical nature, making the current model capable of describing reversible and irreversible processes with a single structure parameter. The parameters of the model are estimated from constant shear rate tests and from the flow curve of the fresh cement slurry. The model predictions are compared to step-down and step-up in stress experiments, and the results show that the model successfully describes experimental data obtained. Interesting phenomena are observed and discussed, including (i) thixotropic behavior during the dormant period, (ii) shear banding, (iii) irreversible changes in cement slurry rheology after the hydration reactions accelerate, and (iv) the existence of a characteristic time for the transition from a thixotropic-yield-stress material to a solid during curing. The predictive capability of the new model includes bifurcation, shear banding, stress overshoots, effects of chemical reactions, and irreversible shear degradation. It is argued that the ideas employed in the present work can be used to incorporate irreversible effects into other thixotropic models, giving rise to the possibility of describing the transient rheological behavior of complex materials in an unprecedented fashion. (c) 2019 The Society of Rheology