Innovations in cast magnesium alloys Belov, V. D.; Koltygin, A. V.; Belov, N. A. ...
Metallurgist (New York),
09/2010, Letnik:
54, Številka:
5-6
Journal Article
Recenzirano
This article examines questions related to aspects of the production of castings of magnesium alloys in molds made by volumetric stamping without the use of the corresponding tooling. Information is ...presented on features of the gating-feeding systems used to obtain magnesium-alloy castings in molds made by volumetric stamping. Also examined are features of the effect of small additions of calcium on the susceptibility of alloys of type ML5 to oxidation during casting in stamped molds. It is shown that the use of calcium in magnesium alloys of the system Mg–Al–Zn is promising for preventing their excessive oxidation.
We analyze variations in the rigidity spectrum of primary cosmic rays during Forbush effects recorded in cycles 20–24 of solar activity on the basis of data from the global network of neutron monitor ...stations processed by global survey. We investigate variations in the rigidity spectrum index of Forbush effects as a function of the solar activity level, phases of the effect, polarity the total magnetic field of the Sun, type and parameters of the source of cosmic ray modulation, etc. Comprehensive analysis of our results revealed regularities in the dynamics of the energy spectrum of galactic cosmic rays that reflect the dynamic processes occurring in the interplanetary space.
P5+ Ion Doped Gd2SiO5:Ce3+ Scintillation Crystal Belov, M. V.; Zavartsev, Yu. D.; Zavertyaev, M. V. ...
Bulletin of the Lebedev Physics Institute,
2020/1, Letnik:
47, Številka:
1
Journal Article
Recenzirano
Ce
3+
, P
5+
, Ca
2+
, and Zn
2+
ion doped Gd
2
SiO
5
crystals are grown by the Czochralski method. The pulsed cathodoluminescence spectra, light yield, and scintillation time under gamma excitation ...are studied. It is first shown that additional doping with P
5+
phosphorus ions decreases crystal cracking in the fabrication of scintillation elements, and increases the scintillation light yield in comparison with commercial Gd
2
SiO
5
:Ce
3+
crystals.
An analysis is made of the geobotanical forecasting technique. Mapping is known to be recognized as the most powerful method of forecasting-geobotanical investigations. A close interrelation between ...geobotanical forecasting and vegetation mapping is demonstrated. To improve objectivity of the findings used cartographic models of modern and predicted vegetation which most fully represent the entire structuralcenotic diversity of plant communities in Prebaikalia, the central region of Baikalian Siberia. The predictive constructions are based on analyzing modern vegetation which always includes structural features of its future that manifest themselves in primary and stable derivative communities. We developed the legend and compiled the map (sc 1:200 000) of the region’s modern vegetation. The state of the natural environment of the Lena- Angara interfluve is assessed having regard to the various functions of plant communities in geosystems. The 1:200 000 map of probability-forecasted (within 200 years) vegetation is presented for Lena-Angara interfluve. It is shown that complete recovery of the primary structure will not occur within 200 years. It is found that it is necessary to carry out predictive-cartographic investigations for the whole of Baikalian Siberia as vegetation of this region is characterized by a decreased activity of recovery processes occurring under the influence of anthropogenic factors. The reason has to do with the harsh natural conditions where it is not worthwhile to pursue extensive nature management, such as is universally the case to date, leading to undesirable economic consequences, because the degree of disturbance to vegetation in a number of areas of Prebaikalia has now reached as critical level. It is concluded that a further policy of nature management on this territory must be built upon the new principles to be approved by government documents.
The structure, composition, physicomechanical properties, tribological properties, and heat resistance of arc-PVD Mo–Si–Al–Zr–N coatings are studied. The coatings contain nitrides ZrN, Mo
2
N, Si
3
N
...4
, and AlN. The coatings have a multilayer structure with a modulation period of 40–45 nm and a crystallite size of 10–15 nm; a hardness of 43 GPa; and parameters
H
IT
/
E
IT
and
of 0.09 and 0.38 GPa, respectively. Samples with the coatings undergo oxidation without substrate exposure upon heating in air at a temperature up to 600°C. The coatings have high wear resistance and a high friction coefficient (~0.97) at elevated temperatures and exhibit cohesion fracture in scratching tests.
Brief results of research at the Department of Zootechnics of the PFUR in more than 30 years are reported on the relationship between cosmophysical activity and animal productivity (the rhythm of ...milk yield of cows and the chemical composition of milk, the biochemical composition of cows' blood). It is established that in even and odd 11-year solar cycles, animals react differently to cosmophysical activity. In even cycles, the increase in solar activity contributes to the growth of milk yields. In odd cycles, increasing solar activity reduces milk yield. The data of scientific observations, covering the periods of even and odd cycles, should be grouped and analyzed separately by cycles. Within 2-3 years, at the lowest peak of solar activity, and 2-3 years - at the top peak of activity (with the change of magnetic poles on the Sun) minimal and unreliable correlations are noted. The strongest correlation was noted in the middle of the rise or decrease in solar activity. The rhythm of milk yield was noted regard-less of the lactation phase of cows. Approximately 1/3 of the time, milk yield increased, 1/3 - decreased and 1/3 - remained at the same level, with fluctuations, with periods from 2.7; 3.3; up to 5.5 days. With an increase in milk yield during 31.0% of lactation days, the content of fat and protein in milk decreased, respectively, 25.8 and 25.4% of the time. With a decrease in milk yield during 33.7% of lactation days, the fat and protein content did not change, respectively, 49.8 and 48.1% days. The most pronounced interval of rhythmicity of the concentration of fat and protein in milk from 2 to 2.5 days with an average value of 2.2 days was established. In addition rhythm 2.8; 3.4; 4.4; 8; 32; 41,1 and 72 days was marked. Approxi-mately with the same cycles in the milk, sugar concentrations, density and acidity were changed.
We present here the results of an experimental study of the effects of capture and retention of intrarenal stones in transcutaneous nephrolithotrypsy by irrigation fluid flow and discuss a ...mathematical model explaining this physical phenomenon. Mathematical modeling and experimental studies were used to formulate the specifications for devices providing increases in stone capture and retention force with a simultaneous reduction in the intrarenal pressure created by the irrigation fluid flow.
Advances in the studies of metamaterials have pushed the development of invisibility cloaks, which suppress scattering by objects within certain frequency ranges. During recent years, there has been ...a transition from a purely theoretical consideration of the cloaking effect to its practical implementation. This paper is an overview of the current state of the art in the area of invisibility cloaks. Special emphasis is put on experimental realizations of such devices.
Detection of antineutrino by the reaction of the inverse
β
-decay can be used for an independent monitoring of a nuclear reactor power. DANSS detector is located directly under a commercial WWER-1000 ...reactor and counts up to 5000 antineutrino per day, providing the accuracy of 1.5% in 2 days of the flux measurement. A powerful system of the passive and active shielding in combination with the fine spatial segmentation of the detector allows to diminish the contribution of the background processes to a level, negligible in comparison to the statistical error. The influence of the nuclear fuel composition on the neutrino flux can be accounted for based on the input from the NPP staff.
The influence of long-term annealing (at 700°C, 30 h) on the structure and mechanical properties of ferritic chromium steels 08Kh17T and 15Kh25T has been comparatively studied after high-temperature ...nitriding and heat treatment (annealing). Both steels in all considered states are characterized by high resistance against oxidation during long-term annealing. Long-term annealing of the steels in the initial non-nitrided state and after nitriding and intermediate annealing at 700°C leads to a decrease in the ultimate tensile strength and yield strength by 10–15%. The maximum decrease in the strength (by 1.2–1.7 times) upon long-term annealing is observed in both steels after preliminary nitriding and annealing at 550°C due to partial coagulation of the nitride phase.
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