High-output thermionic converter based on a metal-oxygen system on the collector

The results of comprehensive experimental investigations of thermionic converters with collectors containing oxygen in an adsorbed near-surface layer and capable of decreasing the barrier index below 2 eV are presented. A vanadium-doped alloy based on chromium, which was investigated in a converter in a pair with different emitters consisting of platinum and single crystal tungsten oriented along the (110) face, was examined as an example of an efficient metal-oxygen system on the collector. The emission-adsorption properties of electrodes and the output electrical characteristics, obtained under working conditions of the converter, as well as surface characteristics of the collector, such as the elemental composition temperature, and others, are described. 6 figures, 21 references. State Science Center of the Russian Federation—A. I. Leipunskii Physics and Power-Engineering Institute. Translated from Atomnaya énergiya, Vol. 89, No. 1, pp. 39–48, July, 2000.     

Strength of Cracked Steel Structural Components at Negative Temperatures

Predictions of the strength of cracked steel structural components at negative temperatures are considered. The elastoplastic stress–strain state of samples at destructive loads is studied by finite-element analysis.     

Influence of Nonfunctional Contact Pads on Printed-Circuit Performance

Russian Engineering Research - The need for nonfunctional contact pads at internal layers of multilayer printed circuit boards (PCB) is still under discussion. Published papers argue on both sides...     

Study of optical absorption in thin films of a-As2Se3 by photocapacitance spectroscopy

Photocapacitive spectroscopy is used for the first time to study optical absorption in thin films of a-As₂Se₃ for optical photons with energies below the gap width. Photocapacitance spectra are obtained over energies of 0.83–1.94 eV and used to characterize the density of localized states in the tail of the valence band and in deep states of charged defects. Aging and illumination of the film are found to affect the level of optical absorption by deep centers. Fiz. Tekh. Poluprovodn. 32, 490–493 (April 1998)     

Strong Hydrogen Bonds in Acetylenedicarboxylic Acid Dihydrate

Acetylenedicarboxylic acid dihydrate (ADAD) represents a complex with strong hydrogen bonding between the carboxylic OH and the water molecule. An X-ray re-examination of the ADAD crystal structure confirms the O^…O distance of the short hydrogen bonds, and clearly shows different bond lengths between the two oxygen atoms with respect to the carbon atom in the carboxyl group, indicating a neutral structure for the complex. The neutral structure was also confirmed by vibrational spectroscopy, as no proton transfer was observed. The diffraction studies also revealed two polymorph modifications: room temperature (α) and low temperature (β), with a phase transition at approximately 4.9 °C. The calculated vibrational spectra are in satisfactory agreement with the experimental spectra. A comparison of the structure and the vibrational spectra between the ADAD and the oxalic acid dihydrate reveals some interesting details. The crystal structures of both crystal hydrates are almost identical; only the O^…O distances of the strongest hydrogen bonds differ by 0.08 Å. Although it was expected that a larger O^…O spacing in the ADAD crystal may significantly change the infrared and Raman spectra, especially for the frequency and the shape of the acidic OH stretching vibration, both the shape and frequency are almost identical, with all subpeaks topped on the broad OH stretching vibration. The O^…O distance dependent are only in- and out-of-plane OH deformations modes. The presence of polarons due to the ionized defects was not observed in the vibrational spectra of ADAD. Therefore, the origin of the broad OH band shape was explained in a similar way to the acid dimers. The anharmonicity of a potential enhances the coupling of the OH stretching with the low-frequency hydrogen bond stretching, which, in addition to the Fermi resonance, structures the band shape of the OH stretching. The fine structure found as a superposition of a broad OH stretching is attributed to Davydov coupling.     

A Linear Optimal Transportation Framework for Quantifying and Visualizing Variations in Sets of Images

Transportation-based metrics for comparing images have long been applied to analyze images, especially where one can interpret the pixel intensities (or derived quantities) as a distribution of ‘mass’ that can be transported without strict geometric constraints. Here we describe a new transportation-based framework for analyzing sets of images. More specifically, we describe a new transportation-related distance between pairs of images, which we denote as linear optimal transportation (LOT). The LOT can be used directly on pixel intensities, and is based on a linearized version of the Kantorovich-Wasserstein metric (an optimal transportation distance, as is the earth mover’s distance). The new framework is especially well suited for computing all pairwise distances for a large database of images efficiently, and thus it can be used for pattern recognition in sets of images. In addition, the new LOT framework also allows for an isometric linear embedding, greatly facilitating the ability to visualize discriminant information in different classes of images. We demonstrate the application of the framework to several tasks such as discriminating nuclear chromatin patterns in cancer cells, decoding differences in facial expressions, galaxy morphologies, as well as sub cellular protein distributions.     

Assessing the reliability of switchgear based on censored statistical information

An assessment of the reliability of a switchgear based on the results of normal testing of electrical endurance and the censored statistical information has been carried out, and a more appropriate law has been found.     

Powers and speeds in electromechanical systems: Hybrid propulsion systems in cars

Mathematical expressions for determining the moments and speeds of the elements of planetary gearboxes are obtained. The possible modes of the operation of an internal combustion engine (ICE) combined with two electric machines are shown. The relation between powers of electric machines and the geometrical parameters of the planetary gear is achieved.     

Formation of liquid film downstream of an atomizer and its disintegration in gaseous medium

Results from experimental and calculation studies of liquid film downstream of a dual-orifice centrifugal atomizer are presented. It is revealed that film generated downstream of an atomizer with a specified geometry may exist in different forms, which depend only on the liquid flow rate.     

Friction and wear of fuel assemblies in water-moderated reactors

Static and dynamic processes that involve frictional forces are experimentally studied. The frictional forces affect the stress of the fuel assembly in all stages of the life cycle.