Nested backward compensation of unmatched perturbations via HOSM observation     

A. Ferreira de Loza  E. Punta  L. Fridman  G. Bartolini  S. Delprat 《Journal of The Franklin Institute》2014

This paper tackles the compensation problem of linear time invariant systems affected by unmatched perturbations. The proposed methodology exploits a high order sliding mode observer, guaranteeing theoretically exact state and perturbation estimation. A compensation based strategy is proposed to cope with the unmatched perturbations. The compensation of the desired coordinate is carried through a nested backward sliding surface design, which compensates some of the non-actuated state components, while the remaining states are maintained to be bounded. The feasibility of the technique was tested in an active suspension vehicle system.¹  相似文献   

Asymmetry of red blood cell motions in a microchannel with a diverging and converging bifurcation     

Leble V  Lima R  Dias R  Fernandes C  Ishikawa T  Imai Y  Yamaguchi T 《Biomicrofluidics》2011,5(4):44120-4412015

In microcirculation, red blood cells (RBCs) flowing through bifurcations may deform considerably due to combination of different phenomena that happen at the micro-scale level, such as: attraction effect, high shear, and extensional stress, all of which may influence the rheological properties and flow behavior of blood. Thus, it is important to investigate in detail the behavior of blood flow occurring at both bifurcations and confluences. In the present paper, by using a micro-PTV system, we investigated the variations of velocity profiles of two working fluids flowing through diverging and converging bifurcations, human red blood cells suspended in dextran 40 with about 14% of hematocrit level (14 Hct) and pure water seeded with fluorescent trace particles. All the measurements were performed in the center plane of rectangular microchannels using a constant flow rate of about 3.0 × 10⁻¹² m³/s. Moreover, the experimental data was compared with numerical results obtained for Newtonian incompressible fluid. The behavior of RBCs was asymmetric at the divergent and convergent side of the geometry, whereas the velocities of tracer particles suspended in pure water were symmetric and well described by numerical simulation. The formation of a red cell-depleted zone immediately downstream of the apex of the converging bifurcation was observed and its effect on velocity profiles of RBCs flow has been investigated. Conversely, a cell-depleted region was not formed around the apex of the diverging bifurcation and as a result the adhesion of RBCs to the wall surface was enhanced in this region.  相似文献   

Self-training through the Internet     

António S. C. Fernandes  Maria João Martins 《European Journal of Engineering Education》2001,26(2):169-177

The development of five courses, aimed at advanced engineering training, using the Internet, is described in this paper. A European consortium was responsible for the development, implementation and testing of the courses through the organization of virtual classes on the Internet. An important outcome was the definition of the training service characteristics, which led to the development of a quality system based on four fundamental concepts: credit, accreditation, certification and qualification. Professionals of several age groups and industrial sectors with different expectations as well as engineering students attended pilot virtual classes. From the trainee's side, we report on how the training opportunity was received and how the training service provided was felt. The main project successes and a few weak points and a number of important recommendations are listed for future reference.  相似文献   

Exploring Resilience in Latina/o Academic Outcomes: A Latent Class Approach     

Alma Boutin-Martinez  Rebeca Mireles-Rios  Karen Nylund-Gibson  Odelia Simon 《Journal of Education for Students Placed at Risk》2019,24(2):174-191

The purpose of this study is to explore the relationship between various protective factors with academic outcomes of Latina/o high school students. We use two groups of protective influences, individual and family, and their relationship to 12th grade mathematics achievement, dropout rates, and enrollment in post-secondary education. Latent class analysis was used to identify academic protective profiles, or latent groups/classes, among high school Latina/o students (N?=?1610) and assess group differences with respect to gender, SES, immigrant status, student’s native language, preschool attendance, and 10th grade mathematics. Results indicated the presence of four academic protective groups, which differed with respect to academic discussions with parents, and attitudes about mathematics. The four classes are compared with respect to academic outcomes and differences are discussed as well as implications for practice.  相似文献   

Engaging plant anatomy and local knowledge on the buriti palm (<Emphasis Type="Italic">Mauritia flexuosa</Emphasis> L.f.: Arecaceae): the microscopic world meets the golden grass artisan’s perspective     

Rebeca V. R. Viana  Vera L. Scatena  Mayra T. Eichemberg  Paulo T. Sano 《Cultural Studies of Science Education》2018,13(1):253-265

Considering that both Western Science and Local Knowledge Systems share a common ground—observations of the natural world—the dialogue between them should not only be possible, but fruitful. Local communities whose livelihoods depend on traditional uses of the local biodiversity not only develop knowledge about nature, making several uses of such knowledge, but, with that process, several inquiries about nature can be raised. Here we present our experience with the engagement of Western Science with golden grass artisan’s knowledge about the buriti palm (M. flexuosa). We applied 25 semi-directive interviews, combined with field diary and participative observation, in two quilombola communities from Jalapão region (Central-Brazil). One of the inquiries that emerged from the artisan’s perspectives was about the differences between male and female buriti palms’ fiber. We then engaged both local and scientific perspectives regarding this issue using plant anatomy as a dialogue instrument. Here we describe this experience and resort to Paulo Freire’s ideas on dialogue to argue that, to integrate Western Science and Local Knowledge Systems in a collaborative and contextualized perspective, the research should be faced as a mutual learning practice.  相似文献   

Organisational cultures in public and private Portuguese Universities: a case study     

Aristides I. Ferreira  Manuela M. Hill 《Higher Education》2008,55(6):637-650

Perceptions of organisational culture made by three categories of staff playing managerial roles in each of two Portuguese Universities (one public and the other private) were compared using a questionnaire adapted from the Organisational Culture Assessment Instrument and translated into Portuguese. The four scales of the questionnaire, designed to measure the Cultures of Clan, Adhocracy, Hierarchy and Market orientation were found to have adequate internal reliabilities, though a factor analysis raised doubts about the construct (factor) validity of two of the scales (Clan and Adhocracy). Application of a MANOVA to scores on the four scales of organisational culture showed, as hypothesised, that the private university was perceived to have significantly stronger cultures of Market orientation and Hierarchy than the public university. No overall difference was found between the universities for the cultures of Clan and Adhocracy. However, general managerial staff in both Universities perceived the cultures of Clan and Adhocracy to be stronger than was the case for technical managerial staff.  相似文献   

Perception of career barriers: The importance of gender and ethnic variables     

Paulo Cardoso  José Ferreira Marques 《International Journal for Educational and Vocational Guidance》2008,8(1):49-61

Differences of gender and ethnicity were examined in terms of the perception of barriers to career development. The Perception of Career Barriers Inventory (IPBC) was administered to a sample of 457 ninth grade students in Portuguese state schools. Gender differences were found, with girls generally scoring higher and in particular on some specific scales. African ethnic participants score higher than Portuguese participants across all the IPBC scales. These findings are more obvious with African participants born in Africa than with those born in Portugal. Implications for future research and practice are discussed.  相似文献   

Epistemic and Political Confrontations Around the Public Policies to Fight COVID-19 Pandemic     

Moura  Cristiano B.  Nascimento  Matheus Monteiro  Lima  Nathan Willig 《Science & Education》2021,30(3):501-525

Science & Education - Our purpose in this article is to discuss the roles for HPSS in Science Education considering the crisis of COVID-19, as well as to think what Science Education could look...  相似文献   

Reading and spelling acquisition in European Portuguese: a preliminary study     

Sandra Fernandes  Paulo Ventura  Luís Querido  José Morais 《Reading and writing》2008,21(8):805-821

We investigated the initial development of reading and spelling in European Portuguese. First-graders, tested in February and June, had to read and spell words and pseudowords. In February there were regularity and graphemic complexity effects, indicating that these children relied on grapheme–phoneme conversion. The lexicality effect found in spelling, in June, suggest that by the end of first grade these children had begun to construct an orthographic lexicon. However, lexical addressing is not inconsistent with phonological mediation as regularization errors increased between the sessions. Additionally, the previously reported similarity in global performance of Portuguese and French beginning readers may conceal processing differences that are related to specific characteristics of the corresponding orthographic codes.

Sandra FernandesEmail:

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Active Learning in Engineering Education: a (re)introduction     

Rui M. Lima  Pernille Hammar Andersson  Elisabeth Saalman 《European Journal of Engineering Education》2017,42(1):1-4

ABSTRACT

The informal network ‘Active Learning in Engineering Education’ (ALE) has been promoting Active Learning since 2001. ALE creates opportunity for practitioners and researchers of engineering education to collaboratively learn how to foster learning of engineering students. The activities in ALE are centred on the vision that learners construct their knowledge based on meaningful activities and knowledge. In 2014, the steering committee of the ALE network reinforced the need to discuss the meaning of Active Learning and that was the base for this proposal for a special issue. More than 40 submissions were reviewed by the European Journal of Engineering Education community and this theme issue ended up with eight contributions, which are different both in their research and Active Learning approaches. These different Active Learning approaches are aligned with the different approaches that can be increasingly found in indexed journals.  相似文献