A 40-mW 55 Mb/s CMOS equalizer for use in magnetic storage readchannels

A monolithic active equalizer in 2-μm CMOS technology is described, suitable for use in magnetic storage read channels employing peak-detection. Computer simulation of the channel and numerical optimization of equalizer performance have led to a 4-pole equalizer which outperforms conventional 7-pole linear-phase pulse-slimming equalizers. Circuits with matched and scaled stray capacitances use low transconductance amplifiers, with a total on-chip power dissipation of 40 mW (excluding output buffers). A master-slave architecture tunes filter pole frequencies and quality factors (Q) to their nominal values against process and temperature variations     

Cognitive, adaptive, and behavioral characteristics of Williams syndrome

The difference of morphological injury between rabbit aorta and pulmonary artery was compared after the animal was exposed to the altitude 5 km (PO2 = 10.8 kPa) for 24 h. Hypoxia caused subendothelial edema, increased vacuoles and injured mitochondria and endoplasmic reticulums in both kinds of endothelial cells. The impairment of pulmonary artery was obviously more severe than aorta and its smooth muscle cells were also affected. Forthermore, the exposure increased mitochondria in pulmonary artery endothelial cells. Bubbled with a mixture air of 95% N2-5% CO2 (PO2 = 4 kPa) led to an increase of pulmonary in tension, while hypoxia to the same extent induced aorta relaxation. These results indicate that hypoxia produces the differential effects on these two kinds of vessels, providing a possible explanation for the production of hypoxic pulmonary hypertension.     

Heterotopic ossification in total hip arthroplasty. The influence of the approach

From 1980 to 1990, 64 cases of Lumbar canal Stenosis have been recorded and operated on at the neurosurgical clinic. The male sex is prevailing and the breakdown by age groups showed a preponderance of the age sections between 31 and 45 and 46 and 60 years. The sciatic pain was the most frequent starting symptom. As far as the physical signs are concerned, the areflexy of the tendon predominates. The saccoradiculography has established the diagnosis in most of the cases. The laminectomy associated with another technique has permitted to obtain the best result of the treatment. With the advent of the T scan, a better estimation of the lumbar canal will be possible, so as to replace the laminectomy by a more adaptable technique: the remeasurement of the lumbar canal.     

Stability of a laminar premixed supersonic free shear layer with chemical reactions

We discuss the stability of a 2-dimensional compressible supersonic flow in the wake of a flat plate. The fluid is a multi-species mixture which is undergoing finite rate chemical reactions. We consider the spatial stability of an infinitesimal disturbance in the fluid. Numerical solutions of the eigenvalue stability equations for both reactive and non-reactive supersonic flows are presented and discussed. The chemical reactions have significant influence on the stability behavior. For instance, a neutral eigenvalue is observed near the freestream Mach Number M_∞ ～- 2.375 for non-reactive case, but disappears when the reaction is turned on. For reactive flows, the eigenvalues are not very dependant on the free stream Mach number. The disturbance amplification rate is higher and the wave speed, c_r is lower for most of the reactive cases when compared with the non-reactive cases.     

Storage stability of solid rocket fuels. 2. Effect of oxidizer loadings

Ageing behaviour, leading to ballistic changes, has been studied as a function of oxidizer loading in polystyrene/ammonium perchlorate solid-propellants. The ageing studies were carried out at 100 °C in air. Change in burning rate decreased as the oxidizer loading increased from 75 to 80%. The change in thermal decomposition rates both at 230 and 260 °C also decreased as the oxidizer loading in the propellants increased. The shapes of the plots of the changes in burning rate and thermal decomposition rate (230 and 260 °C) at different storage times for different oxidizer-loaded propellants seem to be exactly similar. These results lead to the conclusion that the thermal decomposition of the propellant may be responsible for bringing about the ballistic changes during the ageing process. Infrared studies of the binder portion of the aged propellant indicate that peroxide formation takes place during the course of ageing and that peroxide formation for a particular storage time and temperature increases as the loading decreases.     

Formation of Pb during epitaxial growth of PbS on KCl in a vitreous silica hot wall system

Thin monocrystalline films of PbS grown epitaxially from the vapour on KCl in a vitreous silica hot wall system, present lower specular reflectivity than expected. Electron micrography shows that the surfaces of the films are studded with a multitude of small blobs. They scatter partially the incident light. By electron probe microanalysis and Bragg diffractometry it was found that the blobs are made up of elemental Pb and PbS. As basic lead sulphates were also found on the films the presence of elemental Pb is attributed to the roast reduction reaction. We believe that the silica of the apparatus provides the major part of the oxygen involved in this reaction.     

Similarity solutions of a strong shock wave propagation in a mixture of a gas and dusty particles

The similarity solutions of a strong shock wave propagation in a mixture of a gas and small solid particles have been investigated. Similarity solution exists only when the shock is very strong and the surrounding medium is of a constant density and at rest and with negligible counterpressure. The non-dimensional fundamental equations are derived and studied. The results depend on three non-dimensional parameters; i.e. (i) the ratio of the specific heats of the gas γ, (ii) the mass concentration of the solid particles k_p in the mixture and (iii) the ratio of the density of the solid to that of initial density of the gas G. Numerical solutions for various values of γ k_p and G are presented and discussed. The speeds of the shock wave front and its location with various energy releases are given.     

On Lyapunov functions for power systems with transfer conductances

The problem of a two-machine power system for stability studies is formulated, taking into consideration the transfer conductances in the transmission network. Lyapunov function is then obtained using a generalization of Popov's criterion due to Anderson.     

The cementation technique for coating carbon fibres

A tow of carbon fibres was coated with copper, nickel and cobalt by the cementation process. Conditions were optimized to obtain continuous, uniform and adherent coatings on three types of carbon fibres. The surface of the carbon fibres was activated by heating in vacuum at 700° C for about 15 min. The fibres were suspended in an aqueous solution of metal (Cu, Ni, Co) salt which also contained glacial acetic acid. To the solution a displacing agent such as Mg, Al, Zn or Fe was added. The metal was displaced from the solution and plated onto carbon. The thickness of the coating was dependent on the metal salt solution concentration and concentration of the surface activator (glacial acetic acid) in the solution. The appearance (dullness or brightness) of the metal coating was dependent on the concentration of the activator and the amount of displacer metal added. Mechanical testing of the single fibres indicated that the strength and modulus of the coated fibres was dependent on the coating thickness. In general, an increase in the coating thickness decreased the mechanical properties of the coated fibres. The coated fibres were introduced into an aluminium matrix successfully by the vacuum-infiltration technique to obtain composites with a uniform distribution of fibres.