Proposta e implementação de uma arquitetura reconfigurável híbrida para aplicações baseadas em fluxo de dados

The increase of applications complexity has demanded hardware even more flexible and able to achieve higher performance. Traditional hardware solutions have not been successful in providing these applications constraints. General purpose processors have inherent flexibility, since they perform several tasks, however, they can not reach high performance when compared to application-specific devices. Moreover, since application-specific devices perform only few tasks, they achieve high performance, although they have less flexibility. Reconfigurable architectures emerged as an alternative to traditional approaches and have become an area of rising interest over the last decades. The purpose of this new paradigm is to modify the device s behavior according to the application. Thus, it is possible to balance flexibility and performance and also to attend the applications constraints. This work presents the design and implementation of a coarse grained hybrid reconfigurable architecture to stream-based applications. The architecture, named RoSA, consists of a reconfigurable logic attached to a processor. Its goal is to exploit the instruction level parallelism from intensive data-flow applications to accelerate the application s execution on the reconfigurable logic. The instruction level parallelism extraction is done at compile time, thus, this work also presents an optimization phase to the RoSA architecture to be included in the GCC compiler. To design the architecture, this work also presents a methodology based on hardware reuse of datapaths, named RoSE. RoSE aims to visualize the reconfigurable units through reusability levels, which provides area saving and datapath simplification. The architecture presented was implemented in hardware description language (VHDL). It was validated through simulations and prototyping. To characterize performance analysis some benchmarks were used and they demonstrated a speedup of 11x on the execution of some applications

Projeto e implementação em FPGA de um processador com conjunto de instrução reconfigurável utilizando VHDL

The Reconfigurable Computing is an intermediate solution at the resolution of complex problems, making possible to combine the speed of the hardware with the flexibility of the software. An reconfigurable architecture possess some goals, among these the increase of performance. The use of reconfigurable architectures to increase the performance of systems is a well known technology, specially because of the possibility of implementing certain slow algorithms in the current processors directly in hardware. Amongst the various segments that use reconfigurable architectures the reconfigurable processors deserve a special mention. These processors combine the functions of a microprocessor with a reconfigurable logic and can be adapted after the development process. Reconfigurable Instruction Set Processors (RISP) are a subgroup of the reconfigurable processors, that have as goal the reconfiguration of the instruction set of the processor, involving issues such formats, operands and operations of the instructions. This work possess as main objective the development of a RISP processor, combining the techniques of configuration of the set of executed instructions of the processor during the development, and reconfiguration of itself in execution time. The project and implementation in VHDL of this RISP processor has as intention to prove the applicability and the efficiency of two concepts: to use more than one set of fixed instructions, with only one set active in a given time, and the possibility to create and combine new instructions, in a way that the processor pass to recognize and use them in real time as if these existed in the fixed set of instruction. The creation and combination of instructions is made through a reconfiguration unit, incorporated to the processor. This unit allows the user to send custom instructions to the processor, so that later he can use them as if they were fixed instructions of the processor. In this work can also be found simulations of applications involving fixed and custom instructions and results of the comparisons between these applications in relation to the consumption of power and the time of execution, which confirm the attainment of the goals for which the processor was developed

Autoclaved, previously used intravaginal progesterone devices induces estrus and ovulation in anestrous Toggenburg goats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The growing importance of materials that prevent microbial adhesion: antimicrobial effect of medical devices containing silver

Research has clarified the properties required for polymers that resist bacterial colonisation for use in medical devices. The increase in antibiotic-resistant microorganisms has prompted interest in the use of silver as an antimicrobial agent. Silver-based polymers can protect the inner and outer surfaces of devices against the attachment of microorganisms. Thus, this review focuses on the mechanisms of various silver forms as antimicrobial agents against different microorganisms and biofilms as well as the dissociation of silver ions and the resulting reduction in antimicrobial efficacy for medical devices. This work suggests that the characteristics of released silver ions depend on the nature of the silver antimicrobial used and the polymer matrix. In addition, the elementary silver, silver zeolite and silver nanoparticles, used in polymers or as coatings could be used as antimicrobial biomaterials for a variety of promising applications. (C) 2009 Elsevier B. V. and the International Society of Chemotherapy. All rights reserved.

Slow-release fluoride devices: a literature review

Although the prevalence of caries has decreased dramatically over the past decades, it has become a polarised disease, with most of subjects presenting low caries levels and few individuals accounting for most of the caries affected surfaces. Thus it become evident for the need of clinical approaches directed at these high-risk patients, in order to overcome problems related to compliance and low attendance at dental care centres. Slow-release fluoride devices were developed based on the inverse relationship existing between intra-oral fluoride levels and dental caries experience. The two main types of slow-release devices - copolymer membrane type and glass bead - are addressed in the present review. A substantial number of studies have demonstrated that these devices are effective in raising intra-oral F concentrations at levels able to reduce enamel solubility, resulting in a caries-protective effect. Studies in animals and humans demonstrated that the use of these devices was able to also protect the occlusal surfaces, not normally protected by conventional fluoride regimens. However, retention rates have been shown to be the main problem related to these devices and still requires further improvements. Although the results of these studies are very promising, further randomised clinical trials are needed in order to validate the use of these devices in clinical practice. The concept of continuously providing low levels of intra-oral fluoride has great potential for caries prevention in high caries-risk groups.

Application of abrupt cut-off models in the analysis of the capacitance spectra of conjugated polymer devices

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Proposal of Using Ozonated Water to Control Biofilm Formation on Mouth-Related Devices

The purpose of this study was to evaluate the antimicrobial effectiveness and dental applications of ozonated water generated by portable equipment (0.667 mg/L). Total elimination of C. albicans, E. coli and S. mutans planktonic cells was observed after 5 min. Reduction in the number of viable cells of biofilms formed on acrylic resin was observed for C. albicans, S. mutans and E. coli. The same effect was observed on biofilms of E. coli, S. aureus, S. mutans and C. albicans formed on stainless steel. Ozonated water was effective for the disinfection of experimentally contaminated toothbrushes.

An improved tabu-based vector optimal algorithm for design optimizations of electromagnetic devices

This paper introduces an improved tabu-based vector optimal algorithm for multiobjective optimal designs of electromagnetic devices. The improvements include a division of the entire search process, a new method for fitness assignment, a novel scheme for the generation and selection of neighborhood solutions, and so forth. Numerical results on a mathematical function and an engineering multiobjective design problem demonstrate that the proposed method can produce virtually the exact Pareto front, in both parameter and objective spaces, even though the iteration number used by it is only about 70% of that required by its ancestor.

High Verdet constant Ga : S : La : O chalcogenide glasses for magneto-optical devices

The magneto-optical rotation at room temperature was measured for three Ga:S:La:O chalcogenide glasses at several laser lines in the visible. The first sample was a binary system constituted by 70 mol % Ga2S3 and 30 mol % La2O3, whereas in the second and third ones the lanthanum oxide was partially substituted by lanthanum sulfide, keeping the amount of gallium sulfide fixed. A pulsed magnetic field between 50 and 80 kG was used for the Faraday rotation measurements. The Verdet constant for one of the ternary samples was found to be as high as 0.205 min G(-1) cm(-1) at 543 nm, indicating that these chalcogenide glasses are very promising for magneto-optical applications. The data for each sample were fitted using the expected analytical expression for the magneto-optical dispersion. Measurements of the refractive index of the glasses at 632.8 nm are also reported. Data on the magneto-optical properties of two high Verdet constant, heavy-metal oxide diamagnetic glasses are also included for comparison. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)00102-6].

Characterization of ZnO-degraded varistors used in high-tension devices

The effects of the degradation process on the structural, microstructural and electrical properties of ZnO-based varistors were analyzed. Rietveld refinement showed that the BiO2-x phase is affected by the degradation process. Besides the changes in the spinel phase, the degradation process also affects the lattice microstrain in the ZnO phase. Scanning electron microscopy analysis showed electrode-melting failure, while wavelength dispersive X-ray spectroscopy qualitative analysis showed deficiency of oxygen species at the grain boundaries in the degraded samples. Atomic force microscopy using electrostatic mode force illustrated a decrease in the charge density at the grain boundaries of the degraded sample. Transmission electron microscopy showed submicrometric spinel grains embedded in a ZnO matrix, but their average grain size is smaller in the degraded sample than in the standard one. Long pulses appeared to be more harmful for the varistors' properties than short ones, causing higher leakage current values. The electrical characteristics of the degraded sample are partially restored after heat treatment in an oxygen-rich atmosphere. (C) 2006 Elsevier Ltd. All rights reserved.

A phase-shifting control for variable frequency multi-cells interleaved boost pre-regulator based on FPGA device

In this paper were investigated phase-shift control strategies applied to a four cells interleaved high input-power-factor pre-regulator boost rectifier, operating in critical conduction mode, using a non-dissipative commutation cells and frequency modulation. The digital control has been developed using a hardware description language (VHDL) and implemented using the XC2S200E-SpartanII-E/Xilinx FPGA, performing a true critical conduction operation mode for a generic number of interleaved cells. Experimental results are presented, in order to verify the feasibility and performance of the proposed digital control, through the use of a Xilinx FPGA device.

Fabrication of novel light-emitting devices based on green-phosphor/conductive-polymer composites

We report on light-emitting devices based on a green-phosphor compound (Mn-doped zinc silicate, Zn2SiO4: Mn) dispersed in a conductive polymeric blend (poly-o-methoxyaniline/polyvinylene fluoride, POMA/PVDF-TrFE). The devices exhibited high luminance in the green, good stability and homogeneous brilliance over effective areas up to 5 cm(2). The electroluminescence (EL) spectrum presented essentially the same characteristics as the photoluminescence (PL) and cathodoluminescence spectra, indicating that the light emission originates from decay of the same excited species, regardless of the excitation source. Operating characteristics were analyzed with current density - voltage (J - V) and luminance voltage ( L - V) curves to investigate the nature of the electroluminescence of the active material, which is still not completely understood.

Qualitative evaluation of active potential barriers in SnO2-based polycrystalline devices by electrostatic force microscopy

This paper discuss the qualitative use of electrostatic force microscopy to study the grain boundary active potential barrier present in dense SnO2-based polycrystalline semiconductors. The effect of heat treatment under rich- and poor-oxygen atmospheres was evaluated while especially considering the number of active barriers at grain boundary regions. The results show that the number of active barriers decrease after heat treatment in an oxygen-poor atmosphere and increase after heat treatment in oxygen-rich atmospheres. The observed effect was explained by considering the presence of oxidized transition metal elements segregated at grain boundary regions which leads to the p-type character of this region, in agreement with the atomic barrier formation mechanism in metal oxide varistor systems.

The failure analyses on ZnO varistors used in high tension devices

The main purpose of this work is to evaluate the failure caused by electrical discharge on commercial ZnO varistor doped with oxide of Bi, Sb, Si, Cr, Co utilized in electric transmission systems. In order to observe the effect of electrical discharge over the microstructure and electrical properties of the varistors, two kinds of pulses were applied: long pulse (2000 ms) and short pulse (8/20 mu s). In both cases, a decrease in grain size and increase in micropores and leakage current were observed. The degraded samples present oxygen defficiency mainly in the grain boundary and phase tranformation from the bismuth oxide phase. (c) 2005 Springer Science+ Business Media, Inc.