The aim of this work is to describe a new instrument based on the negative expiratory pressure technique able to detect expiratory flow limitation (EFL) in patients with respiratory diseases. First, ...we describe the design details of a virtual instrument able to apply a low pressure at the mouth during tidal expiration, simultaneously measure flow and pressure, and automatically elaborate flow-volume curves. Then, the system accuracy is evaluated investigating normal subjects and patients with chronic obstructive pulmonary disease (COPD). These experimental results revealed higher (p<;;0.001) EFL in COPD patients (58.5+19.9%) than in normal volunteers (1.5+2.5%). These results are in close agreement with the physiology, confirming the high scientific and clinical potential of this system.
Coloured glasses produced commercially by Cebracê, São Paulo, were analysed by the thermoluminescent (TL) method, to verify the possibility of their use as high-dose dosemeters or irradiation ...indicators in industrial areas, due to their easy handling and their low cost. The samples were exposed to different radiation doses, using the Gamma-Cell 220 system (60Co) of IPEN. The TL emission curves presented main peaks at 135, 150 and 145°C in the bronze, brown and green glass samples, respectively. Calibration curves were obtained for the glasses between 50 Gy and 360 kGy. Reproducibility of TL response and the lower detection doses were determined for each kind of glass. All tested glasses showed their usefulness as irradiation indicators and as high-dose dosemeters.
Reorientation Dynamics of a Nematic Elastomer Teixeira, P. I. C.
Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals,
19/8/1/, Letnik:
330, Številka:
1
Journal Article, Conference Proceeding
The relaxation back to the zero-field state of a nematic elastomer that has undergone a Frederiks transition, is investigated by a combination of the "neo-classical" theory of liquid crystal rubber ...elasticity and the simplest time evolution equations for a system described by two coupled, non-conserved order parameters (director and strain). Results are compatible with the recent experimental findings of Chang, Chien and Meyer Phys. Rev. E, 56, 595 (1997). In addition, it is predicted that the absence of a "semi-soft" elastic threshold changes the long-time decay of the effective refractive index of the medium from exponential to inverse power law.
The purpose of this paper is to present a new robust methodology for synchronous communications in a BUS, connecting multi-clock domains. Traditionally, when robust solutions are needed, an ...asynchronous communication is used. However, the low transfer rates associated with asynchronous solutions make them inadequate for high performance digital systems. On the other hand, synchronous communications do not guarantee dependability for all data, especially when different clock domains are interconnected. In this paper we propose to take advantage of these approaches, by combining, the robustness of asynchronous communication and the speed and simplicity of synchronous communications. A structure has been developed to implement the proposed communication approach. A test chip has been designed to implement that structure and prove the concept. The usefulness of the methodology is demonstrated in a complex FPGA data acquisition system. Simulation results are presented.
In nanometer technologies, as variability is becoming one of the leading causes for chip failures, signal integrity is a key issue for high-performance digital System-on-Chip (SoC) products. In this ...paper, analysis is focused on the occurrence of Delay-faults due to Power-supply disturbances in nanometer technologies. Using a previously proposed VT (power supply Voltage and Temperature)-aware time management methodology, it is shown that nanometer technologies impose the need of fault-tolerance methodologies, although the margins of tolerance or fault-free operations are being reduced as technology scales down. SPICE simulation results with 350 nm, 130 nm, 90 nm, 65 nm, 45 nm and 32 nm CMOS technologies show an increasing dependence of propagation delays on power supply variations, as technology is being scaled down. Monte Carlo simulations show that, even in the presence of process variations, a dynamic delay-fault tolerance methodology can be rewarding even at nanometer scale, although the margins for Power-supply variations are becoming smaller.
In recent years there have been major advances in our understanding of the mechanisms of phase separation in polymer and copolymer blends, to the extent that good control of phase-separated ...morphology is a real possibility. Many groups are studying the computational simulation of polymer phase separation. In the light of this, we are exploring methods which will give insight into the mechanical response of multiphase polymers. We present preliminary results from a process which allows the production of a two-dimensional finite-element mesh from the contouring of simulated composition data. We examine the stretching of two-phase structures obtained from a simulation of linear Cahn-Hilliard spinodal phase separation. In the simulations, we assume one phase to be hard, and the other soft, such that the shear modulus ratio G is large (>or= 10(3)). We indicate the effect of varying composition on the material modulus and on the distribution of strains through the stretched material. We also examine in some detail the symmetric structures obtained at 50% composition, in which both phases are at a percolation threshold. Inspired by simulation results for the deformation of these structures, we construct a "scaling" theory, which reproduces the main features of the deformation. Of particular interest is the emergence of a lengthscale, below which the deformation is non-affine. This length is proportional to G(1/4), and hence is still quite small for all reasonable values of this ratio. The same theory predicts that the effective composite modulus scales also as G(1/4), , which is supported by the simulations.
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