Distribution of products around a burning droplet: an analytical approach

A knowledge of the concentration distribution around a burning droplet is essential if accurate estimates are to be made of the transport coefficients in that region which influence the burning rate. There are two aspects of this paper; (1) determination of the concentration profiles, using the simple assumption of constant binary diffusion coefficients for all species, and comparison with experiments; and (2) postulation of a new relation for the therinal conductivity, which takes into account the variations of both temperature and concentrations of various species. First, the theoretical concentration profiles are evaluated and compared with experimental results reported elsewhere [5]. It is found that the agreement between the theory and experiment is fairly satisfactory. Then, by the use of these profiles and the relations proposed in the literature for the thermal conductivity of a mixture of nonpolar gases, a new relation for thermal conductivity: K = (A1 + B1 T) + (A2 + B2 T) xr (21). is suggested for analytical solutions of droplet combustion problems. Equations are presented to evaluate A1, A2, B1, and B2, and values of these terms for a few hydrocarbons are tabulated.

Epoxy resin chamber for high voltage breakdown studies in high vacuum

As the study of electrical breakdown phenomena in vacuum systems, gains more importance, a thorough understanding of the breakdown mechanism at high voltages necessitates a chamber for experimental studies. An epoxy-resin chamber has been constructed by casting ring sections which were joined together. The advantages of such a chamber over the conventional metal or glass chamber are given especially as regards the electric field configuration, high voltage lead-in, and the ease of construction. Special facilities can be incorporated while constructing the chamber which makes it more versatile; for example, in pre-breakdown current measurements, electron beam focusing studies, etc.

Breakdown in p‐n junction diodes made on polycrystalline silicon of large grain size

This communication describes the voltage‐current characteristics in the breakdown region of p‐n junctions made on polycrystalline silicon of large grain size. The observed soft breakdown characteristics have been explained by taking into account the effect of curvature of the junction near the grain boundaries.

Determination of free elemental sulphur in some petroleum products

Uncombined elemental sulphur in petroleum products such as kerosene, diesel, furnace and gear oil has been determined by conversion into copper(I) sulphide at 150–170°. The copper(I) sulphide can be weighed, or its sulphur content determined by the iodimetric method.

Analysis of effects of ambients (temperature and light intensity) on the electrical breakdown in bipolar transistors

This paper presents an analysis of the effects of ambients-temperature and light intensity on the V-l characteristics of bipolar transistors under electrical breakdown. The analysis is based on the transportation and storage of majority carriers in the base region. It is shown that this analysis can explain the observed shift in the V-l characteristics to lower voltages with increase in either temperature or light intensity.

Reactions of bis(isonitrosoethylacetoacetato)palladium(II) with straight chain aliphatic primary amines influence of concentration of the reacting amines on the nature of the products

Reactions of bis(isonitrosoethylacetoacetato)palladium(II), Pd(IEAA)2,with straight chain non-bulky alkylamines, RNH2(R = CH3, C2H5, n-C3H7or n-C4H9) in the mole ratio 1:1 gave bis (B-alkylisonitrosoethylacetoacetateimino)Palladium(II), Pd(R-IEAI)2. In this reaction the coordinated carbonyl groups of Pd(IEAA)2 undergo condensation with amines fo rming Schiff bases (>CNR). On the other hand, the reactions of Pd(IEAA)2 with a large excess of amine yielded N-alkylamido bridgedisonitrosoethylacetoacetatedipalladium(II), μ-(NHR)2[Pd(IEAA)]2 complexes. The complexes are characterized by elemental analyses, magnetic susceptib ility, i.r., p.m.r. and in some cases, nitrogen 1s X-ray photoelectron and mass spectral studies.

Synthetic studies toward the PPAP natural products, prolifenones A and B and hyperforin: an Effenberger cyclization approach

A synthetic approach toward the geranylated PPAP natural products, prolifenones A and B. employing Effenberger cyclization as the key step, is delineated. The efficacy of this approach is further expanded through access to an advanced precursor of hyperforin. (C) 2010 Elsevier Ltd. All rights reserved.

Lubricated Tribology of a Eutectic Aluminium-Silicon Alloy in the Ultra-Mild Wear and Mild Wear Regimes for Long Sliding Times

Aluminium-silicon alloy, an important material used for the construction of internal combustion engines, exhibit pressure induced distinct regimes of wear and friction; ultra-mild and mild. In this work the alloy is slid lubricated against a spherical steel pin at contact pressures characteristic of the two test regimes, at a very low sliding velocity. In both cases, the friction is controlled at the initial stages of sliding by the abrasion of the steel pin by the protruding silicon particles of the disc. The generation of nascent steel chips helps to breakdown the additive in the oil by a cationic exchange that yields chemical products of benefits to the tribology. The friction is initially controlled by abrasion, but the chemical products gain increasing importance in controlling friction with sliding time. After long times, depending on contact pressure, the chemical products determine sliding friction exclusively. In this paper, a host of mechanical and spectroscopic techniques are used to identify and characterize mechanical damage and chemical changes. Although the basic dissipation mechanisms are the same in the two regimes, the matrix remains practically unworn in the low-pressure ultra-mild wear regime. In the higher pressure regime at long sliding times a small but finite wear rate prevails. Incipient plasticity in the subsurface controls the mechanism of wear.