Marx-Type solid-state bipolar modulator topologies: Performance comparison

The operation of generalized Marx-type solid-state bipolar modulators is discussed and compared with simplified Marx-derived circuits, to evaluate their capability to deal with various load conditions. A comparative analysis on the number of switches per cell, fiber optic trigger count, losses, and switch hold-off voltages has been made. A circuit topology is obtained as a compromise in terms of operating performance, trigger simplicity, and switching losses. A five-stage laboratory prototype of this circuit has been assembled using 1200 V insulated gate bipolar transistors (IGBTs) and diodes, operating with 1000 V dc input voltage and 1 kHz frequency, giving 5 kV bipolar pulses, with 2.5 mu s pulse width and 5 mu s relaxation time into resistive, capacitive, and inductive loads.

Integration of e-learning systems with repositories of learning objects

This paper describes a communication model to integrate repositories of programming problems with other e-Learning software components. The motivation for this work comes from the EduJudge project that aims to connect an existing repository of programming problems to learning management systems. When trying to use the existing repositories of learning objects we realized that they are mainly specialized search engines and lack features for integration with other e-Learning systems. With this model we intend to clarify the main features of a programming problem repository, in order to enable the design and development of software components that use it. The two main points of this model are the definition of programming problems as learning objects and the definition of the core functions exposed by the repository. In both cases, this model follows the existing specifications of the IMS standard and proposes extensions to deal with the special requirements of automatic evaluation and grading of programming exercises. In the definition of programming problems as learning objects we introduced a new schema for meta-data. This schema is used to represent meta-data related to automatic evaluation that cannot be conveniently represented using the standard: the type of automatic evaluation; the requirements of the evaluation engine; or the roles of different assets - tests cases, program solutions, etc. In the definition of the core functions we used two different web services flavours - SOAP and REST - and described each function as an operation for each type of interface. We describe also the data types of the arguments of each operation. These data types consist mainly on learning objects and their identifications, but include also usage reports and queries using XQuery.

Describing function of two masses with backlash

This paper analyzes the dynamical properties of systems with backlash and impact phenomena based on the describing function method. It is shown that this type of nonlinearity can be analyzed in the perspective of the fractional calculus theory. The fractional dynamics is compared with that of standard models.

Time domain design of fractional differintegrators using least-squares

In this paper we propose the use of the least-squares based methods for obtaining digital rational approximations (IIR filters) to fractional-order integrators and differentiators of type sα, α∈R. Adoption of the Padé, Prony and Shanks techniques is suggested. These techniques are usually applied in the signal modeling of deterministic signals. These methods yield suboptimal solutions to the problem which only requires finding the solution of a set of linear equations. The results reveal that the least-squares approach gives similar or superior approximations in comparison with other widely used methods. Their effectiveness is illustrated, both in the time and frequency domains, as well in the fractional differintegration of some standard time domain functions.

Extending the learning object definition to represent programming problems

The present generation of eLearning platforms values the interchange of learning objects standards. Nevertheless, for specialized domains these standards are insufficient to fully describe all the assets, especially when they are used as input for other eLearning services. To address this issue we extended an existing learning objects standard to the particular requirements of a specialized domain, namely the automatic evaluation of programming problems. The focus of this paper is the definition of programming problems as learning objects. We introduce a new schema to represent metadata related to automatic evaluation that cannot be conveniently represented using existing standards, such as: the type of automatic evaluation; the requirements of the evaluation engine; or the roles of different assets - tests cases, program solutions, etc. This new schema is being used in an interoperable repository of learning objects, called crimsonHex.

Serologic studies on the behaviour of influenza virus type A in persons of greater São Paulo during 1976, 1978 and 1979

Sera of persons of different age groups collected in 1976, 1978 and 1979 were tested for the presence of HI antibodies against various strains of the H3N2 and H1N1 subtypes of influenza virus. The occurrence of infection by H3N2 subtype was recorded during the 1976-1978 period but in 1979, circulation of this subtype of virus was limited. The prevalence of antibody against A/São Paulo/1/78 (H1N1) was significantly higher than that of antibody to A/USSB/90/77 (HIND in 1978. However in 1979 the predominant strain was A/USSR/90/77 (HIND. Persons under 20 years of age were the most affected by H1N1 subtype. Antibodies to H1N1 subtype were detected in sera of individuals older than 20 years in 1976, before the re-emergence of this strain. Serological results indicate that infections by H3N2 subtype in 1978 occurred in 65.4% of young children (0-4 year group). About 47.0% of children from the 0-4 year group had antibodies to H1N1 subtype in 1979. Antibodies to swine influenza virus were detected in 60% of 60+ year old people.

Using the learning tools interoperability framework for LMS integration in service oriented architectures

The LMS plays an indisputable role in the majority of the eLearning environments. This eLearning system type is often used for presenting, solving and grading simple exercises. However, exercises from complex domains, such as computer programming, require heterogeneous systems such as evaluation engines, learning objects repositories and exercise resolution environments. The coordination of networks of such disparate systems is rather complex. This work presents a standard approach for the coordination of a network of eLearning systems supporting the resolution of exercises. The proposed approach use a pivot component embedded in the LMS with two roles: provide an exercise resolution environment and coordinate the communication between the LMS and other systems exposing their functions as web services. The integration of the pivot component with the LMS relies on the Learning Tools Interoperability. The validation of this approach is made through the integration of the component with LMSs from two vendors.

Pontes pedonais em madeira lamelada colada:caracterização, dimensionamento, patologia e conservação

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Edificações

Type inference for conversation types

Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia Informática

Identification of mating type genes in the bipolar basidiomycetous yeast rhodosporidium toruloides: first insight into the MAT Locus structure of the sporidiobolales

Eukaryotic Cell, Vol.7, Nº6

Design and testing of a radiation hardened 13-bit 80 MS/s pipeline ADC implemented in a 90nm standard CMOS process

Second International Workshop on Analog and Mixed Signal Integrated Circuits for Space Applications (AMICSA 2008), Sintra, Portugal, Setembro de 2008

Inapparent lung involvement in patients with the subacute juvenile type of paracoccidioidomycosis

Three patients with the diagnosis of subacute juvenile paracoccidioidomycosis who, at the time of their first visit, had no signs or symptoms of lung involvement, were studied. Initially the diagnosis was confirmed by the observation of P. brasiliensis in biopsy material obtained from clinically involved lymphadenopathies. The lung X-rays done in all patients, did not reveal pathologic changes, although it was possible to observe and isolate the fungus from sputum samples obtained from the three patients. This fact reinforces the pulmonary genesis of the mycosis and proofs the existence of a pulmonary primary infection, even in patients with the juvenile manifestations, in whom the lung component is obscured by the predominant lymph node involvement.

Anaerobic bacteria: an investigation of metabolic important enzymes: a novel type of oxygen reductase and enzymes of the tetrapyrrole biosynthesis

Desulfovibrio desulfuricans was the first species of a sulphatereducing bacterium to be isolated, in 1895. Since that time, many questions were raised in the scientific community regarding the metabolic and ecological aspects of these bacteria. At present, there is still a myriad of open questions remaining to be answered to enlarge our knowledge of the metabolic pathways operative in these bacteria that have implications in the sulfur cycle, in biocorrosion, namely in sewers and in oil and gas systems, and in bioremediation of several toxic metals. The work presented in this dissertation aimed at contributing with new insights of enzymes involved in two different metabolic systems on Desulfovibrio species, namely enzymes that play a role in the response to oxidative stress and that are involved in the haem biosynthetic pathway.(...)

Como é que é com o é que? Análise de estruturas com é que em variedades não standard do português europeu

Dissertação de Mestrado em Ciências da Linguagem

A multitask ATPase serving different ABC-type sugar importers in Bacillus subtilis

Journal of Bacteriology (Out 2010) 5312-5318