Hankel-Bessel laser beams

An analytical solution of the scalar Helmholtz equation to describe the propagation of a laser light beam in the positive direction of the optical axis is derived. The complex amplitude of such a beam is found to be in direct proportion to the product of two linearly independent solutions of Kummer's differential equation. Relationships for a particular case of such beams-namely, the Hankel-Bessel (HB) beams-are deduced. The focusing of the HB beams is studied.     

加拿大Athabasca油砂中部分沥青质油不易分离的原因

1. Introduction Commercial recovery of bitumen from oil sands iscurrently achieved by means of water based separationprocesses. While most of these separation methods arebased on the Hot Water Extraction Process, the need toconserve energy has resulted …     

Self-reproduction of multimode hermite-gaussian beams

The condition for the self-reproduction of multimode Hermite-Gaussian beams is obtained and analyzed. Partial self-reproduction planes are also considered. A numerical example is presented. Pis’ma Zh. Tekh. Fiz. 25, 62–69 (June 26, 1999)     

A generalization of the Jensen inequality

A new approach for estimating functions and functionals based on the concept of function superconvexity and a generalization of the Jensen inequality is proposed. A new concept is introduced and the associated analytical results are substantiated. Some nontrivial estimates of functions are derived. Translated from Kibemetika i Sistemnyi Analiz, No. 2, pp. 89–99, March–April, 2000.     

Pentane-Insoluble Matter from Conventional and Heavy Crudes: Relationships Between Thermal Characteristics and Molecular Parameters

Nearly 50% of bitumen derived from Athabasca oilsands is pitch. The pentane-insoluble fraction is the major coke producer during thermal cracking. Here, we evaluate the thermal behavior of pentane insolubles from various oil sources by correlating thermogravimetric data with structural parameters. The effect of any entrained mineral solids on the thermal properties results was also investigated. Coke yields depended significantly on aromaticity, H/C atomic ratios, molecular weight, chain length, and equivalent molecular diameter. With the exception of highly aliphatic Daqing conventional oil, coke yields correlated well with the calculated structural parameters. Asphaltene from bitumen was about average in its coke-forming propensity. Mineral solids had practically no effect on thermal behavior.     

Electrooptic tuning of InP-based microphotonic Fabry-Perot filters

This paper presents the experimental results for compact (20- and 40-/spl mu/m-long) electrooptically tuned deeply etched Fabry-Perot (F-P) filters in InP-based material. Both the quantum-confined Stark effect (QCSE) and carrier-injection (C-I) effects were implemented to achieve tunability of these microcavity filters. Red and blue shifts of the transmission peaks in the order of 1 to 2 nm were observed for both effects, and the limitations on C-I due to thermal effect are clearly demonstrated and discussed. The advantages and disadvantages of both tuning mechanisms are highlighted.     

Photonic crystal Mikaelian lens

A mode solution in the form of a hyperbolic secant for a two-dimensional gradient medium with the refractive index also in the form of hyperbolic secant is derived. A photonic crystal analogue of the cylindrical Mikaelian lens is found and comparative numerical simulation of plane wave diffraction by both micro-lenses with the help of the two-dimensional FDTD-method is performed. The text was submitted by the authors in English.     

DISTRIBUTION AND TYPES OF SOLIDS ASSOCIATED WITH BITUMEN

In the conventional Hot Water Extraction Process bitumen is separated as a froth that is then diluted with naphtha and subjected to two stages of centrifugation. The resulting bitumen solution still contains residual water, dissolved salts and mineral solids. Before upgrading the solvent and other volatile components are removed by topping at 524°C. The salts and mineral solids remain with topped bitumen; their presence can lead to serious operational problems in the bitumen upgrading process. In the present work the solids associated with bitumen (BS) have been identified as mainly ultra-fine (nano sized) aluminosilicate clays coated with strongly bound toluene insoluble organic material having “asphaitene characteristics”. It is proposed that these ultra-fine clays with their strong tendency to collect at oil-water interfaces, are the key component responsible for the presence of intractable water and associated salts in bitumen froth.