Dispersion relation of the collective excitations in a resonantly driven polariton fluid

Exciton-polaritons in semiconductor microcavities constitute the archetypal realization of a quantum fluid of light. Under coherent optical drive, remarkable effects such as superfluidity, dark solitons or the nucleation of hydrodynamic vortices have been observed. These phenomena can be all understood as a specific manifestation of collective excitations forming on top of the polariton condensate. In this work, we performed a Brillouin scattering experiment to measure their dispersion relation $\omega(\mathbf{k})$ directly. The result, such as a speed of sound which is apparently twice too low, cannot be explained upon considering the polariton condensate alone. In a combined theoretical and experimental analysis, we demonstrate that the presence of a reservoir of long-lived excitons interacting with polaritons has a dramatic influence on the nature and characteristic of the quantum fluid, and that it explains our measurement quantitatively. This work clarifies the role of such a reservoir in the different polariton hydrodynamics phenomena occurring under resonant optical drive. It also provides an unambiguous tool to determine the condensate-to-reservoir fraction in the quantum fluid, and sets an accurate framework to approach novel ideas for polariton-based quantum-optical applications

Development of advanced winding condition control technology of electric motors based on pulsed method

More than 80 percent of all electrical energy customers are electric motors. Therefore one of the prospects of resource-effective technologies in power industry is control of rotating electric equipment condition. Winding defects are one of the main causes of electric motor failures. Reliable control of winding condition is an urgent task of modern electrical engineering technology. The present article is devoted to the research of pulsed method application of transformer winding control for electric motor winding condition control. The procedure of winding condition control technology is described. The proposed method is based on the known pulsed method. The essential difference between the two methods is that only one probing impulse is used which is a probing impulse and response signal at once. The results of diagnostic procedure research at different winding defects are given. It is established that the place of winding damage corresponds to characteristic impulse changes. The defect of definite types causes specific changes of the probing impulse form. Therefore, different winding defects could be found with high accuracy along winding

Improved measurements of ICRF antenna input impedance at ASDEX upgrade during ICRF coupling studies

A new set of diagnostics has been implemented on ASDEX Upgrade to measure the input impedance of the ICRF antennas, in the form of a voltage and current probe pair installed on each feeding line of every antenna. Besides allowing the measurement of the reflection coefficient Gamma of each antenna port, the probes have two advantages: first, they are located close to the antenna ports (similar to 3 m) and thus the measurements are not affected by the uncertainties due to the transmission and matching network; second, they are independent of matching conditions. These diagnostics have been used to study the behavior of the ASDEX Upgrade antennas while changing the plasma shape (low to high triangularity) and applying magnetic perturbations (MPs) via saddle coils. Scans in the separatrix position R-sep were also performed. Upper triangularity delta(o) was increased from 0.1 to 0.3 (with the lower triangularity delta(o) kept roughly constant at 0.45) and significant decreases in vertical bar Gamma vertical bar (up to similar to 30%, markedly improving antenna coupling) and moderate changes in phase (up to similar to 5 degrees) off on each feeding line were observed approximately at delta(o) >= 0.29. During MPs (in similar to 0.5 s pulses with a coil current of 1 kA), a smaller response was observed: 6% - 7% in vertical bar Gamma vertical bar, with changes in phase of 5 apparently due to R p scans only. As 1 is usually in the range 0.8 - 0.9, this still leads to a significant increase in possible coupled power. Numerical simulations of the antenna behavior were carried out using the FELICE code; the simulation results are in qualitative agreement with experimental measurements. The results presented here complement the studies on the influence of gas injection and MPs on the ICRF antenna performance presented in [4]

Ecological assessment of the aftereffect of phosphogypsum on the stabilization of the carbon balance of the regenerated topsoil of degraded sod-podzolic soils

Against the background of global climate changes, agroecological problems of erosion and agrogenic degradation of intensively used arable soils have become more acute. This problem is most acute in the case of old-arable sod-podzolic soils with initially low humus content and small thickness of their sod horizons. Our research carried out with the support of project No. 075-15-2021-1030 of the Ministry of Science and Higher Education of Russia, provides investigation the influence of industrial waste in the production of phosphorous fertilizers - phosphogypsum on the stabilization of the carbon balance of the regenerated topsoil of degraded sod-podzolic soils. The research was carried out at the Agroecological Station of the Field Experimental Station of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy in fall of 2022 and in summer of 2023. The use of phosphogypsum in a dose of 1.5 t/ha contributed to the significant accumulation of organic carbon in the topsoil of the studied sod-podzolic soils – in comparison with the control. In combination with compost from bird dropping at a dose of 2.0 t/ha, the aftereffect of the use of phosphogypsum essentially increases, that indicates good prospects for the validation of this technology as a natural climate project

Experience in strengthening foundations and foundations on technogenic soils

The article discusses modern methods of strengthening foundations on artificial bases that have received excessive precipitation and rolls. In the course of studies, it was found that the use of bored piles allows transferring the load to the underlying reliable foundation at any depth, and cementing the foundation soil contributes to improving the physical and mechanical characteristics of the backfill soil

Agroecological assessment of the efficiency of utilization of quail manure in the restoration of disturbed sod-podzolic soils with the formation of a stable herbage

The most acute environmental problems of our time include large volumes of bird droppings produced annually at large livestock complexes. At the same time, the sod-podzolic soils dominating in the Non-Chernozem zone of the European part of Russia are characterized by low reserves of humus, which quickly fall with intensive agricultural use and soil anthropogenic degradation. To restore degraded sod-podzolic soils, a peat-sand substrate enriched with compost from quail manure without and with the application of phosphogypsum to stabilize organic compounds of compost was used with the support of project No. 075-15-2021-1030 of the Ministry of Science and Higher Education of Russia. The vegetation experiment showed the maximum increase in plant biomass of the herbage in the variant with the combined use of compost and phosphogypsum: respectively, 30% higher than the control one. In the summer, there is an increased intensity of soil CO2 emissions in the variants with compost, but with a multiple more active increase in grass biomass growing, so one can talk about the atmosphere carbon sequestering nature of the technology of utilization of quail droppings during the restoration of disturbed sod-podzolic soils with the formation of a stable herbage

Advantages of pre-fabricated reinforced concrete construction in Iraq

With its building infrastructure almost completely destroyed during the military conflict, modern Iraq is facing an urgent need for a number of measures to increase the quality of installation, construction and reconstruction jobs and to reduce timeframes taking into account local and climatic features. To achieve this, the priority task is to develop methods and theoretical recommendations based on the analysis of existing methods for calculating construction timeframes, ones that would most accurately reflect the influence of such factors as cement class, type and an average daily air temperature. The climatic conditions in Iraq impact negatively on the properties of hardened concrete. Specifically, concrete mixture shrinks more rapidly, which entails a change in its physico-mechanical properties and further corrosion of reinforcement bars at joints in monolithic prefabricated housing construction. This paper aims to determine factors that affect construction timeframes and quality for prefabricated reinforced concrete buildings, and to develop a model on the basis of statistical research to determine the concrete hardening time at joints in prefabricated frame housing construction

Iron metallurgy of the Xianbei period in Tuva (Southern Siberia)

We present results of the complex investigation of large-scale iron production at the site of Katylyg 5 (Tuva, Southern Siberia) dating to 3rd-4th c. AD. The excavations have uncovered nine trapezoid underground smelting furnaces, a tonne of smelting slag, smithing remains and a charcoal production zone. The investigation of slag by Optical microscopy, SEM-EDS and ICP-MS confirms the performance of smelting and smithing operations at the site, and also suggests that the smelted ore was magnetite, associated with quartz. The presence of copper (bronze) prills in most of the smithing slag indicates that copper was worked alongside iron in the smithing hearths. The spatial division of the site into three different production zones (smelting, smithing and charcoalproduction) suggests a well-organized and self-sufficient industry, that was probably tightly controlled throughout all stages of the chaîne op´eratoire. The trapezoid furnaces identified at Katylyg, are also known from Cis-Baikal region where they date from the end of the 1st millennium BCE and throughout most of the 1st millennium AD. This suggests that the technology of trapezoid furnaces, along with the Kokel culture to which they are attributed, likely emerged in Tuva with the migrations from the Baikal region due to the westward Xianbei expansion during 1st-3rd c. AD

Studying radiation hardness of a cadmium tungstate crystal based radiation detector

The given article considers radiation hardness of an X-ray detector used in production of non-destructive testing instruments and inspection systems. In the course of research, experiments were carried out to estimate radiation hardness of a detector based on cadmium tungstate crystal and its structural components individually. The article describes a layout of an experimental facility that was used for measurements of radiation hardness. The radiation dose dependence of the photodiode current is presented, when it is excited by a light flux of a scintillator or by an external light source. Experiments were carried out to estimate radiation hardness of two types of optical glue used in detector production; they are based on silicon rubber and epoxy. With the help of a spectrophotometer and cobalt gun, each of the glue samples was measured for a relative light transmission factor with different wavelengths, depending on the radiation dose. The obtained data are presented in a comprehensive analysis of the results. It was determined, which of the glue samples is most suitable for production of detectors working under exposure to strong radiation