Specific approaches towards design of the thermoelectric oxides

Sustainable energy supply to the population based on environmentally friendly and efficient technologies represents one of the major societal challenges in 21st century. One of the solutions is thermoelectric conversion of waste heat or solar heat into electricity, using sustainable and scalable devices, with self-sufficiency to enable mobile or remote applications. This talk will feature some promising strategies to design performing oxidebased thermoelectrics, including redox-promoted enhancement of the thermoelectric properties and a self-forming nanocomposite concept, where a controllable interplay between exsolution of the nanophases and modification of the host matrix suppresses the thermal transport, while imparting the high electrical performance. Particular attention will be given to laser floating zone technique as a tool to process ceramic samples appropriate for fabrication of the thermoelectric generators.publishe

New guidelines for oxide thermoelectrics: redox tuning and controlled interactions

Development of thermoelectrics for high-temperature applications imposes several essential requirements on the material properties. In some energy-conversion scenarios the cost and thermal stability requirements may dominate over efficiency issues, making abundant, hightemperature-stable and low-toxic oxides an interesting alternative TEs. The talk will feature some promising strategies to design performing oxide-based thermoelectrics. Particular attention will be given to the approaches where the inherent redox flexibility of oxides is invoked for tailoring the TE properties through in-situ formation of nanocomposites with enhanced performance. Another strategy is based on a self-forming nanocomposite concept for ZnO-based thermoelectrics, where a controllable interplay between exsolution of the nanophases and modification of the host matrix suppresses the thermal transport, while imparting the high electrical performance. The mechanisms behind the observed enhancement in thermoelectric properties and specific pathways towards high TE performance in oxides will be proposed and discussed.publishe

High-temperature thermoelectric energy harvesting: materials and approaches

Thermoelectric (TE) technology allows direct production of electrical energy from waste heat and natural heat sources. Although today thermoelectrics are hardly competitive with heat engines at large scale, absence of moving parts, inherent simplicity and scalability of this solid-state technology enable various applications in automotive/aerospace sector, in harsh and remote environments and for solar energy conversion. This talk will focus on opportunities for high-temperature thermoelectric energy harvesting and feature some promising approaches to design performing oxide-based thermoelectrics.publishe

Selected approaches for designing oxide thermoelectrics

Thermoelectric (TE) effect provides an elegant solution for conversion of the waste heat into electrical energy, based on the intrinsically simple technology employing no moving parts and possessing self-sufficiency to enable mobile or remote applications. In some energy-conversion scenarios the cost and thermal stability requirements may dominate over effciency issues, making abundant, high-temperature-stable and low-toxic oxides an interesting alternative TE material. The talk will focus on opportunities for high-temperature thermoelectric energy harvesting and feature some promising strategies to design performing oxide-based thermoelectrics. Particular attention will be given to the approaches where inherent redox flexibility of oxides is invoked for tailoring the functional TE properties, and some nanocomposite concepts.publishe

Water vole (Arvicola amphibius) as an object of long-term biomonitoring in a floodplain area (Western Siberia, Russia)

The paper is devoted to the dynamics of the water vole population in the conditions of total deforestation of valley forests and their subsequent restoration. We analyzed the relative population of small mammals in the typical biotopes in the Tom River basin (Western Siberia) on the border of the forest-steppe and taiga zones. From 1978 to 2019, 1,139 water voles Arvicola amphibius (Linnaeus, 1758) (synonym of A. terrestris) were caught with 50-meter trapping grooves; for 788 individuals we assessed the condition of non-metric features (phenes) of the skull. It was found that changes in the population level are non-cyclical, while against the background of a generally low occurrence of the species in the region, the population level increased tenfold in some years. It was shown that such episodic population surges can significantly impact the structure of the community of small mammals. In the valley of the Tom River, the water vole prefers inhabit wet meadows and ecotone areas between the meadow and the dark coniferous taiga forest. During the years of population surges, the water vole intensely occupies new nesting sites due to the dispersal activity of young animals but at the same time retains the original biotopic preferences. Dispersal of the species takes place in waterlogged wetlands. Most of the animals caught during the peak of their numbers were young animals of late broods born from overwintered individuals. The conducted phenetic analysis revealed the heterogeneity of young animals during the population surge, which allowed us to assume the participation of several populations in the formation of the peak. In the final surge year, the surge was characterized by an extremely low percentage of participation in the breeding of young females and the appearance of a large number of weakened animals, which led to crisis in the species population and the disappearance of the water vole from the captures. The research shows that one cannot predict the success of this process at the current stage; therefore, after flooding, it is necessary to continue monitoring

Dimension on Discrete Spaces

In this paper we develop some combinatorial models for continuous spaces. In this spirit we study the approximations of continuous spaces by graphs, molecular spaces and coordinate matrices. We define the dimension on a discrete space by means of axioms, and the axioms are based on an obvious geometrical background. This work presents some discrete models of n-dimensional Euclidean spaces, n-dimensional spheres, a torus and a projective plane. It explains how to construct new discrete spaces and describes in this connection several three-dimensional closed surfaces with some topological singularities It also analyzes the topology of (3+1)-spacetime. We are also discussing the question by R. Sorkin [19] about how to derive the system of simplicial complexes from a system of open covering of a topological space S.Comment: 16 pages, 8 figures, Latex. Figures are not included, available from the author upon request. Preprint SU-GP-93/1-1. To appear in "International Journal of Theoretical Physics

Выбор численного значения критерия для определения вида короткого замыкания в адаптивной микропроцессорной токовой защите линий

The paper considers a principle for determination of a short circuit type which is used in the mathematical model of adaptive micro-processing protection with the purpose to improve sensitivity. As a result of a calculative experiment dependences ΔI(t) for various short circuit types (three- and two-phase short circuits) have been obtained at a number of points of the investigated power network. These dependences make it possible to determine a numerical value of ΔI coefficient. A comparative analysis has been made to study an operation of adaptive and non-adaptive microprocessing protections in the case of asymmetric damages of the investigated power network just in the same points.Рассмотрен принцип определения вида КЗ, используемый в математической модели адаптивной микропроцессорной защиты для улучшения чувствительности. В результате вычислительного эксперимента получены зависимости ΔI(t) для различных видов КЗ (трех и двухфазных) в разных точках исследуемой электрической сети. Эти зависимости позволили определить численное значение коэффициента ΔI. Проведен сравнительный анализ характеристик срабатывания адаптивной и не адаптивной микропроцессорной защит при несимметричном повреждении в одних и тех же точках исследуемой электрической сети

Astrometric Control of the Inertiality of the Hipparcos Catalog

Based on the most complete list of the results of an individual comparison of the proper motions for stars of various programs common to the Hipparcos catalog, each of which is an independent realization of the inertial reference frame with regard to stellar proper motions, we redetermined the vector $\omega$ of residual rotation of the ICRS system relative to the extragalactic reference frame. The equatorial components of this vector were found to be the following: $\omega_x = +0.04\pm 0.15$ mas yr$^{-1}$, $\omega_y = +0.18\pm 0.12$ mas yr$^{-1}$, and $\omega_z = -0.35\pm 0.09$ mas yr$^{-1}$.Comment: 8 pages, 1 figur

Oxide thermoelectrics prepared by laser melting: effects of processing atmosphere

Traditional thermoelectric materials suffer from two main problems, the toxicity/scarcity of the elements used and their stability at high temperatures or in non-inert atmospheres. Thermoelectric oxides appear to be a promising alternative to traditional materials due to natural abundance of the constituents and high thermal stability. This work focuses on the processing of these materials using the Laser Floating Zone (LFZ) technique. Particular emphasis is given to LFZ processing under various redox atmospheres, allowing unique opportunities for tuning the structural, microstructural and thermoelectric properties. This technique allows the growth of fully dense fibres, as well as the formation of metastable phases and/or promoting different oxidation states by adjusting the growth conditions. Here we report the processing of model manganite- and titanate-based materials including donorsubstituted Ca(Pr)MnO3 and Ti(Ta)O2 systems. XRD/SEM/EDS studies demonstrate some guidelines for tuning the phase composition and microstructure by adjusting the growth rate under different redox conditions. We report high power factor values of 303 μWm-1K -2 at 1120 K for the Ca(Pr)MnO3 system and 317 μWm-1K -2 for the Ti(Ta)O2 system. The obtained results suggest that LFZ is a suitable technique for processing thermoelectric oxides if optimized control over growth parameters and re-equilibration conditions is imposed.publishe