Yerevan State University
  • Yerevan, Armenia
Recent publications
A new hybrid method for the construction of control actions of a linear control system with constant coefficients is considered in this paper. It is assumed in this paper that a part of the discussed system meets some conditions. Some states of the main system are considered to be control actions for a subsystem for which and LQR stabilizer is acquired. Then, those control actions of the subsystem are used to construct the control actions for the main system. In the problem of controlling the motion of a complex linear system of an inverted spherical pendulum on a moving base, a new approach to the construction of control actions (hybrid action method) was used. It is assumed that a component of the complex system under discussion satisfies certain conditions. The inertial forces at the center of mass of the base of the composite system are considered to be the controlling influences on the inversion of the pendulum, for which the LQR stabilizer was purchased. The determined internal control actions on the inverted pendulum are then used to construct external control actions on the base of the composite system. In the end, a numerical analysis was carried out.
The present study investigated the anion composition of drinking water from various cities and villages in Armenia, including spring water and tap water samples. The simultaneous separation was achieved for fluoride, chloride, bromide, nitrite, nitrate, sulfate, and phosphate anions with the correlation coefficients >0.998. Validation of the method was carried out in accordance with the requirements of guidelines in terms of selectivity, specificity, system suitability, linearity, accuracy, precision, lower limits of detection and quantitation, robustness, and stability. The method was suitable for routine drinking water quality assessment in line with the national or World Health Organization (WHO) regulations. The validated method was further used to analyze drinking water samples from different regions of Armenia. The observed concentrations for the anions in drinking water complied with the WHO limits for drinking water with some exceptions. The test method can be submitted to quality control laboratories as a convenient and practical tool for routine analysis and monitoring studies.
Flexible transparent electrodes, encompassing the combination of optical transparency and electrical conductivity, empower numerous optoelectronic applications. While the main efforts nowadays concentrate on developing wire meshes and conductive oxides, those technologies are still in a quest to find a balance between price, performance, and versatility. Here we propose a new platform, encompassing the advantages of nanophotonic design and roll‐to‐roll large‐scale lithography fabrication tools, granting an ultimate balance between optical, electrical, and mechanical properties. The design is based on an array of silica microspheres deposited on a patterned thin aluminum film attached to a flexible polymer matrix. Microspheres are designed to squeeze 80% light through nanoscale apertures with the aid of the photonic nanojet effect given the light impinges the structure from the top. The photonic structure blocks the transmission for the backpropagation direction thus granting the device with the high 5‐fold level of asymmetry. The patterned layer demonstrates a remarkable 2.8 Ω sq ⁻¹ sheet resistance comparable to that of a continuous metal layer. The high conductivity is shown to be maintained after a repeatable application of strain on the flexible electrode. Such remarkable optical, mechanical and electrical properties, makes the demonstrated device an essential component for applications, where such attributes are critically required.
In the world of the 21st century, international economic structures are increasingly increasing their influence on the world market, which directly affects the economic potential of the member countries of these organizations and the development and prosperity of the national economy. EAEU is considered one of such structures, which during its nearly 10 years of activity has had a great impact on the internal output of the member states, as well as on ensuring interstate economic cooperation and the economic integration process. The St. Petersburg meeting had a special role and significance within the framework of EAEU, during which a strategy regulating and coordinating the structure's further work was promoted and a document was signed that created visible prospects in the near future in order to clarify its actions and upcoming steps. The authors of the scientific work, taking into account the importance and strategic significance of this document, considered it necessary to present in the form of an article what prospective positive impact the document can have for the organization and its member countries and what its goals are.
In this study, we report on the crystallographic, optical, and electrochemical properties of Yttrium (Y³⁺) doped ZnO nanoparticles synthesized by using the sol-gel method. The incorporation of Y³⁺ ions resulted in a significant reduction in the optical bandgap, from 3.26 eV for pure ZnO to 2.67 eV for Y-C nanoparticles, improving their light absorption capacity under visible light. X-ray diffraction analysis revealed a hexagonal wurtzite structure, showing an increase in crystallite size with the incorporation of Y³⁺ doping. This was accompanied by superior photocatalytic performance, where Y-B (4% Y³⁺) doped ZnO nanoparticles exhibited remarkable 97% degradation efficiency for methylene blue (MB), 4.4 times greater than that of undoped ZnO. Electrochemical analysis revealed an improvement in specific capacitance, ranging from 20.56 F/g to 75.88 F/g at various scan rates, highlighting the potential of Y-ZnO as a material for energy storage applications. These enhancements can be attributed to the unique influence of Y³⁺ ions, which induce lattice expansion and promote charge transfer efficiency. The synthesized Y³⁺ doped ZnO nanoparticles can be potential candidates for industrial applications such as environmental remediation through photocatalysis, and energy storage devices like supercapacitors. Graphical Abstract
In the post-Soviet space, the South Caucasus has always stood out as the most conflict-ridden region. Three powerful neighbors of the region - Russia, Turkey and Iran - constantly monitor developments here, seeking to increase the dose of influence. As a result of the change of power, in 2012, the Georgian Dream party came to power in Georgia, and anti-Russian sentiments in the country began to decline. Despite all the pressure, the Georgian authorities did not join the sanctions imposed by the United States and the European Union against Russia. The «Georgian Dream» party put forward a legislative initiative on foreign agents in 2023, after which it faced mass protests. As a result, the bill was withdrawn, but already in the next year, 2024, the majority of members of parliament again introduced the bill and on May 28th it was adopted. In Georgia, in 2023-2024, domestic political processes are taking place around this law, including the issue of changing the foreign policy vector.
The paper presents the provisions, directions and projects of the Saudi Arabian project "Vision 2030", as well as the steps aimed at the transformation of society and social reforms. The paper examines the root causes of the emergence, initiation and development of the project up to 2016 and beyond. It also mentions the main directions, strategies and goals of the program, as well as the social reforms implemented after 2016, when the Saudi Arabian prince Mohammed bin Salman entered the scene. The paper also includes an examination of the mechanisms by which the mega-project "Vision 2030" should be implemented, as well as the challenges and obstacles standing in the way of the latter.
Education has a continuous nature, and researchers study the phenomenon of metacognition at various developmental stages of a person. One of the best factors for the self-actualization of younger schoolchildren in the educational process involves the development of metacognitive skills, which can be formed and developed only in the presence of pedagogical conditions for metacognitive knowledge and experience of younger schoolchildren. In organizing the education of younger schoolchildren, the role of metacognition and metacognitive knowledge is emphasized as processes of self-regulation and self-organization of the individual. Research shows that metacognitive processes help learners understand their own thoughts, make generalizing conclusions, and that certain pedagogical conditions and planned teaching are necessary to achieve this. In the psychology of education and the theory of modern pedagogy, the study of metacognition is considered one of the leading areas. The investigation of the phenomenon of metacognition in the fields of educational theory and history is conducted from the perspective of improving the educational process; in this case, the potential for the development of metacognitive processes is clearly high in terms of acquiring academic knowledge. By studying metacognitive processes in education, we have identified the pedagogical conditions for the formation of metacognitive knowledge and experience in younger schoolchildren, which can enhance the effectiveness of their learning.
The article presents a research rationale for the technological system of developing metacognitive knowledge and skills in primary school students. The role of metacognition in elementary school is discussed, and its necessity is justified from the perspective of the effectiveness of the educational process. The importance of the metacognitive approach for younger school-age students is emphasized. We conducted a pedagogical scientific experiment, and the methodology is presented in the article. We carried out a three-tiered quantitative and qualitative study involving the parent community, teachers, and students. By comparing the survey data from parents, teachers, and students, our research demonstrated the need for metacognitive knowledge and experience in primary school. Despite both the parent and teacher communities being largely unfamiliar with the concept of "metacognition" during the study, it became clear that particularly the parent community noted a lack of initiative among students. In this case, students not only lack developed metacognitive skills but also show no desire to engage in academic activities.
Semiconductor nanowires are known for peculiar geometry providing unique electronic and optical properties. Substrate with vertical nanowires is highly non-uniform surface attractive in terms of study of live cells that...
Climate justice is increasingly prominent in climate change communication and advocacy but little is known about public understanding of the concept or how widely it resonates with different groups. In our global survey of 5,627 adults in 11 countries spanning the global north and south, most participants (66.2%) had never heard of climate justice. Nonetheless, endorsement of climate justice beliefs was widespread (for example, acknowledging the disproportionate impact of climate change on poor people and the underpinning roles of capitalism and colonialism in the climate crisis). Climate justice beliefs were also associated with various indices of climate action and policy support. These associations tended to be stronger in countries with high GHG emissions and where social inequality is also more politically salient. The results highlight the value of climate justice as a motive for climate action across diverse geographical contexts.
The problem of the professional competencies and importance of specialists in their activities are presented in this article. The target concept that is analyzed in the article is professional competence. The results of the research were collected a sample of 4 professions: doctors, psychologists, military and pedagogue, because in the last year they were working in the crisis conditions in our country. The aim of the article is to do factor analysis of the collected data and create out leaderboard of competencies to ensure of professional quality for specialists who are working in the crisis situations. In summarizing our research sample, we selected 191 specialists, four focus groups and contents about competencies. The results showed that there are three groups of competencies with higher stability in professional activity in crisis situations: needs (abilities, skills, and physiological responses), motivation (financial stability, real rewards of work, career growth), intrapersonal resources (personality growth, humanistic and spiritual feeling, openness). Based on personal resources, a specialist can develop abilities that will contribute to the most effective construction of professional activity. Also, continuing education, training and professional development opportunities make the development of professional competences more stimulating, smooth the difficulties of work activities and reduce burnout and stress.
This study presents, for the first time, a new method for the synthesis of polymers containing different ratios of oxidized quinoid and reduced benzenoid units in polyaniline (PANi)‐like structure. Copolymers were synthesized by an oxidative copolymerization method of p‐phenylene diamine (p‐PDA) and o‐anisidine (o‐An) in an organic medium using different initial compositions of monomers. The compositions of the copolymer were determined based on ¹H NMR spectral data. The thermal stability, electrical conductivity, morphology, and solubility were studied and a comparative analysis with polyaniline and corresponding homopolymers was been carried out. The thermal behavior of copolymers was studied using thermogravimetric analysis and differential scanning calorimetry. It was found that during heating one endothermic process of water evaporation and two exothermic processes occur, which depend on copolymer composition, and only 30% weight loss occurs up to 600 °C. It is shown that room‐temperature conductivity of copolymers doped with hydrochloric and sulfuric acids ranges from 10⁻⁵ to 10⁻³ S cm⁻¹ and increases with increasing concentration of o‐anisidine structural units. The conductivity of iodine‐doped copolymers is of the same order as the conductivity of iodine‐doped PANi in emeraldine and leucoemeraldine forms. The morphology of doped copolymers depends on the co‐monomer ratio and the type of dopants.
Using proton–proton collision data corresponding to an integrated luminosity of 140 fb1140\hbox { fb}^{-1} 140 fb - 1 collected by the CMS experiment at s=13TeV\sqrt{s}= 13\,\text {Te}\hspace{-.08em}\text {V} s = 13 Te V , the {{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} Λ b 0 → J / ψ Ξ - K + decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the {{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{{\uppsi }} ({2\textrm{S}})} {{\Lambda }} Λ b 0 → ψ ( 2 S ) Λ decay, is measured to be \mathcal {B}({{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} )/\mathcal {B}({{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{{\uppsi }} ({2\textrm{S}})} {{\Lambda }} ) = [3.38\pm 1.02\pm 0.61\pm 0.03]\% B ( Λ b 0 → J / ψ Ξ - K + ) / B ( Λ b 0 → ψ ( 2 S ) Λ ) = [ 3.38 ± 1.02 ± 0.61 ± 0.03 ] % , where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in \mathcal {B}({{{\uppsi }} ({2\textrm{S}})} \rightarrow {{\text {J}/\uppsi }} {{{\uppi }} ^{{+}}} {{{\uppi }} ^{{-}}} ) B ( ψ ( 2 S ) → J / ψ π + π - ) and \mathcal {B}({{{\Xi }} ^{{-}}} \rightarrow {{\Lambda }} {{{\uppi }} ^{{-}}} ) B ( Ξ - → Λ π - ) .
This study explores the molecular mechanisms behind the differential responses of Saccharomyces cerevisiae industrial strains (ATCC 9804 and ATCC 13007) to osmotic stress. We observed that, in contrast to ATCC 9804 strain, sodium flux in ATCC 13,007 is not N, N’-dicyclohexylcarbodiimide (DCCD)-sensitive under osmotic stress, suggesting a distinct ion homeostasis mechanism. Under aerobic conditions, osmotic stress increased reduced SH groups by 45% in ATCC 9804 and 34% in ATCC 13,007. In contrast, under microaerophilic conditions, both strains experienced a 50% reduction in thiol groups. Notably, ATCC 13,007 exhibited a 1.5-fold increase in catalase (CAT) activity under aerobic stress compared to standard conditions, while ATCC 9804 showed enhanced CAT activity due to SH group binding. Additionally, superoxide dismutase (SOD) activity was doubled during aerobic growth in both strains, with ATCC 13,007 showing a 1.5-fold higher SOD activity under osmotic stress. The results demonstrate that S. cerevisiae adapts to osmotic stress differently under aerobic and microaerophilic conditions, with aerobic conditions promoting Pma-Ena-Trk interplay, reduced thiol levels and increased catalase activity, while microaerophilic conditions demonstrate Pma-Nha-Trk interplay and shifts redox balance towards oxidized thiol groups and enhance superoxide dismutase activity. Understanding these mechanisms can aid in developing stress-resistant yeast strains for industrial applications.
We obtain recovery formulas for coefficients of orthonormal spline series by means of its sum, if the partial sums of an orthonormal spline series converge in measure to a function and the majorant of partial sums satisfies some necessary condition, provided that the spline system corresponds to a “regular” sequence. Additionally, it is proved that the regularity of the sequence is essential.
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2,431 members
Grigor Alaverdyan
  • Chair of Applied electrodynamics end modeling
Levon Haroutunyan
  • Faculty of Physics
Karen Trchounian
  • Department of Biochemistry Microbiology and Biotechnology
Chubaryan Anahit
  • Faculty of Informatics and Applied Mathematics
David Hovhannisyan
  • Faculty of Radiophysics
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