228 research outputs found
Reliability of AC thick-film electroluminescent lamps
The reliability of AC thick-film EL devices has been studied. The AC thickfilm
EL devices were fabricated by Novatech Inc. using the industrial print screen
technology. The analysis of reasons for failure has been proposed. The dependence of EL
lamp parameters on physical properties of the device EL layers was found. Our analysis
of the breakdown spot showed that improvement of reliability can be reached using the
additional dielectric layer between the phosphor layer and transparent electrode, high
concentration of phosphor powder 70 % and binder 30 %, balanced resistance between
the electric circuit and EL lamp. The thickness of the phosphor layer was equal to H =
(1 + √3/2)D (hexagonal packing), where D is the mean diameter of phosphor particles.
The reliability dependence of EL lamp on a water adsorption property of packaging
material was revealed
8H-, 10H-, 14H-SiC formation in 6H-3C silicon carbide phase transitions
In this paper the results of photoluminescence researches devoted to phase
transitions in 6H-3C-SiC have been presented. High pure 6H-SiC crystals grown by
Tairov’s method with and without polytype joint before and after plastic deformation at
high temperature annealing were investigated using optical spectroscopy. Low
temperature photoluminescence changes in the transition phase of SiC crystal represented
with the stalking fault spectra within the temperature range 4.2 to 35 K. The stalking
fault spectra indicate formation of metastable nanostructures in SiC crystals (14H₁
, 10H₂ , 14H₂ ). The phononless part of each stalking fault spectrum
consists of two components of radiative recombination that are responsible for hexagonal
and cubic arrangement of atoms. Each of radiative recombination components in the
stalking fault spectrum has the width of entire band 34 meV and shifts relative to each
other by 26 meV. The overlap area of those components equals to 8 meV. The super-fine
structure of the recombination components in spectrum is observed, and it is related to
different Si – Si or C – C and Si – C bonds. Behavior of all the stalking fault spectra is
similar (temperature, decay of luminescence). The processes of the phase transition are
explained by the mechanism of interfacial rearrangements in the SiC crystals
Nanostructures in lightly doped silicon carbide crystals with polytypic defects
In this work, photoluminescence spectra of lightly doped SiC crystals with ingrown
original defects are reported. Undoped SiC single crystals with the impurity
concentration of ND – NA ~ (2…8)*10¹⁶ cm⁻³, NA ~ (2…8)*10¹⁷ cm⁻³, and ND – NA ~
(1…5)*10¹⁷ cm⁻³, ND = 10¹⁸ cm⁻³ were investigated. The analysis of absorption,
excitation and low temperature photoluminescence spectra suggests formation of a new
micro-phase during the growth process and appearance of the deep-level (DL) spectra.
The complex spectra of the crystals can be decomposed into the so-called DLi (i = 1, 2,
3, 4) spectra. The appearance of the DLi spectrum is associated with formation of new
nano-phases. Data of photoluminescence, excitation and absorption spectra show the
uniformity of different DLi spectra. Structurally, the general complexity of the DLi
spectra correlated with the degree of disorder of the crystal and was connected with onedimensional
disorder, the same as in the case of the stacking fault (SFi) spectra. The DLi
spectra differ from SFi spectra and have other principles of construction and behavior.
The DLi spectra are placed on a broad donor-acceptor pairs emission band in crystals
with higher concentrations of non-compensated impurities. The excitation spectra for the
DLi and SFi spectra coincide and indicate formation of nanostructures 14H₁,
10H₂, 14H₂, 8H<44
External impacts on SiC nanostructures in pure and lightly doped silicon carbide crystals
Influence of plastic deformation and high-temperature annealing (T = 2100 °C, t = 1 h) on SiC crystals with grown polytypic junctions demonstrating SF and DL spectra have been presented. SF-i and DL-i type luminescence are inherent to SiC crystals with distortions of the structure related with availability of packing defects that lead to onedimensional disordering (along the c-axis). They are a most expressed in doped crystals with original growth defects. DL luminescence appears in pure crystals at plastic deformation and in doped crystals at a hydrostatic pressure. It enhances at the high temperature annealing, too
Flexible electroluminescent panels
Recently developed ac ZnS-powder electroluminescence (EL) devices have
flexibility (thickness is about 60 µm) and can be multisegment, multicolor, as well as
rolled and bent. All colors (white, blue, blue-green, green, and orange) have been
investigated for improvement of their operational characteristics. Many factors including
the type of phosphor, formation method, contacts, initial input power (peak voltage and
frequency), type of input power, and environment safety which define the panel's
properties are discussed
3C-6H transformation in heated cubic silicon carbide 3C-SiC
Results of the research on the photoluminescence study of the 3C-6H-SiC
phase transformation are presented. 3C-SiC crystals with in grown 3C-6H transformation
and pure perfect 3C-SiC crystals grown by the Tairov-Tsvetkov method without a
polytypes joint after high temperature annealing were investigated. Fine structure at the
energy of E = 2.73, 2.79 eV, E = 2.588 eV, and E = 2.48 eV that appeared after annealing
was described. The role of stacking faults in the process of structure transformation was
investigated
Three-dimensional localized coherent structures of surface turbulence. III Experiment and model validation
The paper continues a series of publications devoted to the 3D nonlinear
localized coherent structures on the surface of vertically falling liquid
films. The work is primarily focussed on experimental investigations. We study:
(i) instabilities and transitions leading to 3D coherent structures; (ii)
characteristics of these structures. Some nonstationary effects are also
studied numerically. Our experimental results, as well as the results of other
investigators, are in a good agreement with our theoretical and numerical
predictions.Comment: 42 pages, 15 figure
Structure of photoluminescence DL-spectra and phase transformation in lightly doped SiC crystals and films
In this work, the results of investigations of DLi spectra in α-SiC crystals and films with a low impurity concentration have been presented. Photoluminescence spectra of lightly doped SiC single crystals and films with the impurity concentration of ND–NA ~ (2…8)∙10¹⁶ cm⁻³, ND ~ (5…8)∙10¹⁷ cm⁻³, and ND–NA >3∙10¹⁷ cm⁻³, ND ≥ 1∙10¹⁸ cm⁻³ (NDLsamples) were investigated within the temperature range 4.2…77 K. Complex spectroscopic study of one-dimensional disordered structures caused by solid phase transformations in SiC crystals was presented. Disordered growth D-layers in lightly doped crystals and α-SiC films were investigated using low temperature photoluminescence. The analysis testifies that DL and SF spectra hand-in-hand follow the structure transformations. It has been shown that the DL and SF spectra of luminescence reflect the fundamental logic of SiC polytypes structure. This allows to observe the structure changes at the phase transformations, the growth of SiC polytypes and to control their aggregates
Mitigation carbon emissions by microalgae: Assessing the viability of culture Arthrospira platensis grown on high CO2 concentrations
In this work, experimentally evaluated the viability of a consortium microalgae Arthrospira platensis rsemsu P Bios with heterotrophic bacteria when cultivated in a gas-air mixture with high concentrations of CO2 (from 0.04 to 9%). A laboratory setup was created to test the viability of microalgae strains at high concentrations of CO2. The experiments were carried out using 12 photobioreactors with a culture medium volume of 4 L each, placed in a gas chamber, which makes it possible to create elevated CO2 concentrations in the gas-air medium. The maximum growth rate of biomass of microalgae A. platensis is 170 mg/(l per day), the maximum absolute increase in biomass for 12 days is 1540 mg/l. The relatively low growth rate and absolute increase in the biomass of A. platensis at all concentrations of CO2 in the gas-air mixture may indicate that this culture requires a longer laboratory adaptation to high concentrations of CO2. The high cell viability found in all experiments by cytochemical staining of cells with methylene blue indicates the acquired tolerance of the culture to elevated CO2 concentrations (3–9%). However, after 12 days of the experiment with 9% CO2, morphometric signs of cell suppression are detected, which is expressed in deviations of the cell shape from normal, elongation (lack of division) and an increase in the number of dead cells. Quantitative characteristics of the microalgae consortium viability have been obtained
ИНВЕСТИЦИОННО-ИННОВАЦИОННЫЙ ПОТЕНЦИАЛ РОССИЙСКИХ РЕГИОНОВ
Purpose: the main purpose of the article is to study the current state of the investment and innovation process in the regions of Russia. To achieve this goal, the article solved the following problemsthe: to describe measures to ensure a balanced innovative growth of Russian regions; to substantiate the need for large-scale increase and effective use of investment funds to stimulate the transition to a new quality of economic growth based on the deployment of innovative processes; to investigate the problems of development of large and small business in the regions, as sources of innovation and job creation; to carry out an analysis the cluster approach as the most priority area with great potential for creating new competitive advantages of the regional economy; to evaluate the effectiveness of management tools that have a direct impact on the innovation space in the regions.Methods: the study was conducted using systematic, logical, comparative analysis, grouping and generalization methods, which made it possible to ensure the validity of the results and conclusions of the study.Results: the factors influencing on the investment and innovation development of the regions have been identified, the management tasks solved in interaction at the level of the state, the region and the industrial complex have been identified. These factors allow multiplying and effectively using the opportunities for large and small business in order to modernize, provide the necessary investment support for the innovative development of regions and the country. Using these approaches give the opportunity to increase the effectiveness and quality of the influence of these factors and tasks on the innovative development of the regions and to adapt their strategy of innovative modernization.Conclusions and relevance: the article show the special role of active investment-innovative interaction between the national and regional levels of public administration for implementation of modernization processes in the economy in order to build a common innovation space in the whole country.Цель: Основная цель статьи состоит в исследовании современного состояния инвестиционно-инновационного процесса в регионах России. Для достижения поставленной цели в статье решены следующие задачи: дана характеристика мер по обеспечению сбалансированного инновационного роста регионов России; обоснована необходимость масштабного наращивания и эффективного использования инвестиционных средств с целью стимулирования перехода к новому качеству экономического роста на основе развертывания инновационных процессов; исследованы проблемы развития крупного и малого предпринимательства в регионах, как источников источниках инноваций и создания рабочих мест; проведен анализ кластерного подхода как наиболее приоритетного направления, имеющего большие потенциальные возможности формирования новых конкурентных преимуществ региональной экономики; оценена эффективность инструментов управления, оказывающих непосредственное воздействие на инновационное пространство в регионах.Методология проведения работы: Исследование велось с использованием методов системного, логического, сравнительного анализа, группировки и обобщения, позволивших обеспечить обоснованность результатов и выводов проведенного исследования.Результаты работы: Выявлены факторы, влияющие на инвестиционно-инновационное развитие регионов, определены управленческие задачи, решаемые во взаимодействии на уровне государства, региона и промышленного комплекса, позволяющие приумножать и эффективно использовать в интересах модернизации возможности крупного и малого предпринимательства, обеспечивать необходимую инвестиционную поддержку инновационному развитию регионов РФ и страны в целом. Использование указанных подходов позволяет повысить эффективность и качество влияния указанных факторов и задач на инновационное развитие регионов, и скорректировать с их учетом стратегию инновационной модернизации экономики регионов.Выводы: Материалы, изложенные в статье, показывают особую роль активного инвестиционно-инновационного взаимодействия между национальным и региональным уровнями государственного управления в ходе реализации модернизационных процессов в экономике с целью построения единого инновационного пространства на территории страны в целом
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