Influence of DTH Hammer Impact Energy on Drilling-with-Casing System Performance

Water well drilling-with-casing equipment is described in the article. Construction diagrams and field test results of series-production and new drilling-with-casing DTH hammers possessing higher impact energy are analyzed. The economic study of water well drilling cost in geological conditions of the Republic of Altai is performed.     

A Thin-Film Platform for Chemical Gas Sensors

In the study, a technique for formation of planar microheaters that make it possible to heat an active zone to a temperature higher than 500°С is proposed and successfully implemented. The developed heating elements are distinguished by low power consumption, short response time, and extremely high resistance to impact loads. The synthetic approaches used in the work (anodic oxidation, photolithography, and magnetron sputtering) feature manufacturability and scaling simplicity. This makes planar heating elements a promising platform based on which semiconductor and thermocatalytic sensors of toxic and explosive gases may be created.     

A Compact High-Voltage Power Supply for an Accelerating Installation

A compact high-voltage power supply for an accelerating installation that uses high-frequency (25 kHz) voltage conversion is described. The power supply provides a variable voltage of 5 to 100 kV at a load current of up to 250 A and three independently variable voltages of 0–100 V (100 mA), 0–2000 V (5 mA), and 1–15 kV (50 A), which are required for operating the cold-cathode ion source used in the installation. The output-voltage ripple is <0.05%. The power-supply efficiency is no less than 70%.     

Combined Methods of Analysis of Metal-Containing Raw Material (Review)

Methods of analysis of reusable metal-containing material (RMR) are considered in the review: X-ray fluorescence, atomic absorption spectrophotometry, and atomic emission and mass spectrometry with inductively coupled plasma. Peculiarities of the applied methods are shown, and a method of analysis with consideration of the specificity of RMR should be developed for every object. In the most cases, the methods of sample processing harmonized with the applied method of analysis and sample content.     

effect of the parameters of AlN/GaN/AlGaN and AlN/GaN/InAlN heterostructures with a two-dimensional electron gas on their electrical properties and the characteristics of transistors on their basis

The effect of the layer thickness and composition in AlGaN/AlN/GaN and InAlN/AlN/GaN transistor heterostructures with a two-dimensional electron gas on their electrical and the static parameters of test transistors fabricated from such heterostructures are experimentally and theoretically studied. It is shown that the use of an InAlN barrier layer instead of AlGaN results in a more than twofold increase in the carrier concentration in the channel, which leads to a corresponding increase in the saturation current. In situ dielectric-coating deposition on the InAlN/AlN/GaN heterostructure surface during growth process allows an increase in the maximum saturation current and breakdown voltages while retaining high transconductance.     

Optically active layers of silicon doped with erbium during sublimation molecular-beam epitaxy

A study is made of the electrical, optical, and structural properties of Si:Er layers produced by sublimation molecular-beam epitaxy. The Er and O contents in the layers, grown at 400–600°C, were as high as 5×10¹⁸ and 4×10¹⁹ cm⁻³, respectively. The electron concentration at 300 K was ∼10% of the total erbium concentration and the electron mobility was as high as 550 cm²/(V·s). Intense photoluminescence at 1.537 μm was observed from all the structures up to 100–140 K. The structure of the optically active centers associated with Er depended on the conditions under which the layers were grown. Fiz. Tekh. Poluprovodn. 33, 156–160 (February 1999)     

The Application of Different Physical Approaches for The Description of Structural Features in Wheat and Rye Starches. A DSC Study

Starches isolated from wheat (Rapoport's variety) at different stages of maturation and from completely maturated rye (Viatka‐2 variety) were investigated in excess of water and in 0.6 M KCl using high sensitivity differential scanning microcalorimetry (HSDSC). Applying some physico‐chemical approaches, the starch polymorphous structure, the thickness of the crystalline lamellae and the thermodynamic parameters characterizing their surface faces were determined. It has been established that wheat and rye starches belong to the A‐type starches. It is suggested that during biosynthesis of granules the formation of the A‐type structure is accompanied by an accumulation of crystal defects. This process leads to a decrease in the melting temperature of starches.     

Corrosion Protection of Aluminum Alloys AMg3 and D16 with Chromate-Free Conversion Coatings in a Tropical Marine Climate

Protection of Metals and Physical Chemistry of Surfaces - Abstract—In this paper, chromate-free conversion coatings on aluminum alloys D16 and AMg3 are studied in a tropical marine climate....     

Arrangement of the computer code for the prediction of forest fire spread

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