[en] Annealing of 99.84% Ni deformed 50% gave an angular distribution of annihilation photons essentially different from that of 99.95% Ni. Heat treatment of 99.84% ni 2 hr at 100-300⁰ resulted in the formation of vacancy complexes. The annihilation of positrons trapped by these complexes resulted in a narrower distribution with a higher max

[en] Silicon nitride hard coatings on tool steel produced by ion beam mixing following sputter or vapour deposition were investigated by RBS and Vickers microhardness measurements. Atomic mixing in the coating/steel interface region resulting in an improved adhesion and in a significant increase of the microhardness of the surface layers was found. Ion beam mixing with gas ions and high fluences leads to blistering of the implanted atoms in the silicon nitride layer. (author) 5 refs.; 8 figs

[en] The effects of tornado-like pressure transients upon dampers and blowers in nuclear air cleaning systems were studied. For the dampers pressure drop as a function of flow rate was obtained and an empirical relationship developed. Transient response was examined for several types of dampers, as was structural integrity. Both centrifugal and axi-vane blowers were tested and transient characteristic curves were generated in outrunning and backflow situations. The transient characteristic curves do not necessarily match the quasi-steady characteristic curves

[en] Wear-resisting surface layers showing excellent adhesion to steel can be produced by ion beam-induced admixing as well as by implantation-assisted coating. The influence on the substrate of the ion beam beyond the region of the top coating results in the wear-inhibiting characteristics being retained even after attrition of the layer of hard material. (author)

[en] FIRIN is a computer program used by DOE fire protection engineers to simulate hypothetical fire accidents in compartments at DOE facilities. The FIRIN code is typically used in conjunction with a ventilation system code such as FIRAC, which models the impact of the fire compartment upon the rest of the system. The code described here, FIRINPC is a PC based implementation of the full mainframe code FIRIN. In addition, FIRINPC contains graphics support for monitoring the progress of the simulation during execution and for reviewing the complete results of the simulation upon completion of the run. This document describes how to install, test, and subsequently use the code FIRINPC, and addresses differences in usage between the PC version of the code and its mainframe predecessor. The PC version contains all of the modeling capabilities of the earlier version, with additional graphics support. This user's guide is a supplement to the original FIRIN report published by the NRC. FIRAC is a computer program used by DOE fire protection engineers to simulate the transient response of complete ventilation system to fire induced transients. FIRAC has the ability to use the FIRIN code as the driving function or source term for the ventilation system response. The current version of FIRAC does not contain interactive graphics capabilities. A third program, called POST, is made available for reviewing the results of a previous FIRIN or FIRAC simulation, without having to recompute the numerical simulation. POST uses the output data files created by FIRINPC and FIRACPC to avoid recomputation

[en] This paper presents the results of mathematically modeling a first-order phase change for the melting of a solid. The mathematical model will be validated against an experiment. The experiment will be the melting of paraffin as it undergoes a phase change from solid to liquid. The authors approximate the partial differential equation describing the enthalpy balance by a variable grid finite difference algorithm. This work will not address interface melting where phase change is occurring at a sharp interface, and is limited to the analysis of a first-order phase change for a homogeneous mixture where mass transfer, crystal growth and reactions are neglected

[en] One possible method for the formation of thin monocrystalline silicon layers on insulators is ion implantation of high doses of nitrogen or oxygen at energies above about 150 keV producing Si³N⁴ or SiO² respectively. The authors report on the influence of current density on the damage level in the silicon top layer in a dose range leading to good insulation in the buried silicon nitride. (Auth.)

No abstract available

[en] The one-dimensional nonlinear inverse heat conduction problem is considered. A new technique for estimating the surface variances of the predicted surface fluxes and temperatures based on an adjoint formulation is presented. The surface variances are related to the measurement variances and to an estimate of the initial condition variances. The only assumption necessary to apply the technique is that of additive measurement errors. Two test cases with three sets of boundary conditions are studied. The surface variance estimates given by the adjoint formulation and direct estimation are shown to be in good agreement

[en] Gas pressure cells techniques are well adapted to neutron scattering applications. They can routinely be used at least up to pressures of 0.5 GPa in a wide temperature range, they allow for an accurate pressure control and also provide the chemical activity for the study of materials where the gas is not only the pressure transmitting medium but also a chemical constituent of the system. We present some of the gas pressure cells which were developed by us for specific needs and discuss their design and performance