Impact ionization in silicon dioxide at fields in the breakdown range

A new method is described for the evaluation of impact ionization coefficients, α, in insulators by the measurement of current transients which grow due to impact ionization. Impact ionization coefficients for SiO₂ evaluated by this method obey roughly the relation α = α₀ exp (?H/F) where F is the field. For p type substrates α₀ = 6.5 × 10¹¹cm^?1 and H = 1.8 × 10⁸V/cm.     

Evaluating Project Completion Times When Activity Times are Erlang Distributed

One aspect of project planning risk assessment is to do with the uncertainty of the project duration. This uncertainty can be quantified by determining the project completion time distribution. A brief review of the existing literature on project duration risk assessment methodologies is given and their advantages and disadvantages evaluated. A development of the moments method based on Erlang distribution of activity times provides an accurate estimate of a project completion time distribution for a large range of practical situations and also is the basis upon which multi-modal input distributions of activity times can be handled. The method is assessed by a number of illustrative examples.     

The Mechanism of the Polymerization of Styrene by Perchloric Acid

Abstract

The kinetics of the polymerization of styrene, initiated by anhydrous perchloric acid in carbon tetrachloride solution and in mixtures of methylene chloride and carbon tetrachloride, have been studied by NMR and GLC methods. In carbon tetrachloride the reaction is zeroth order. The kinetics, together with the known effects of dielectric constant and pressure on the reaction rate, suggest that the rate-determining step may be the formation of a carbonium perchlorate ion-pair, associated with neutral molecules of styrene.     

Iron (II) tetrakis(diaquaplatinum) octacarboxyphthalocyanine supported on multi-walled carbon nanotubes as effective electrocatalyst for oxygen reduction reaction in alkaline medium

Oxygen reduction reaction (ORR) in alkaline medium at iron (II) tetrakis (diaquaplatinum) octacarboxyphthalocyanine (PtFeOCPc) catalyst supported on multi-walled carbon nanotubes (MWCNTs) has been described. The ORR followed the direct 4-electron transfer process, with a very low onset potential (approximately zero volts vs. Ag|AgCl, saturated KCl) and at a kinetic rate constant, 2.78 × 10^? 2 cm s^? 1. The results clearly showed that the ORR activity at the MWCNT-PtFeOCPc platform is comparable or even better than recent reports with other electrocatalysts, thus a promising catalytic platform for cathodic process in fuel cell device.     

On finite-zone solutions of relativistic Toda lattices

The finite-zone solutions of relativistic Toda lattices are investigated using the recurrence relations method. As a result, a nonlinear bundle of relativistic Toda lattices is with corresponding stationary and dynamical systems. New Poisson and Hamiltonian structures are introduced. Then the problem of integrating the obtained canonical systems are reduced to the Jacobi problem of inversion.     

Measurement of frictional interactions at soil-tool interfaces

A diaphragm transducer has been developed for measuring local soil-tool interactions with essentially no normal deflection of the diaphragm. For tool motion within a pre-formed channel in soil, the normal contact pressure was found to be very nearly constant, while the tangential friction force followed a transient behaviour toward a steady-state value. Steady-state friction coefficients ranged from 0.06 to 0.25, smaller values being associated with faster velocities and shorter stroke length.