Theses and Dissertations
http://nur.nu.edu.kz:80/handle/123456789/4188
2024-03-29T13:38:04ZNOVEL ORGANIC TANDEM SOLAR CELLS
http://nur.nu.edu.kz:80/handle/123456789/7249
NOVEL ORGANIC TANDEM SOLAR CELLS
Ernest, Adiyiah Asare
Organic tandem solar cells have attracted significant attention as a promising technology for next-generation photovoltaics due to their potential to achieve high power conversion efficiencies. In this study, we present a simulation-based approach using transfer matrix modeling to investigate the optical and electrical properties of organic tandem solar cells. We investigate the influence of different device parameters such as the thickness of the active layers on the device performance. The simulation results demonstrate that the optimized thicknesses of the active layers involved in the tandem structure can significantly improve the short circuit current JSC thereby increasing the power conversion efficiency compared to the single-junction solar cells. Additionally, the transfer matrix model provides a comprehensive understanding of the optical behavior of the device, including the absorption and reflection of light at different interfaces. These results provide valuable insights into the design and optimization of high-performance organic tandem solar cells.
2023-01-01T00:00:00ZExpectation Values of Singular Operators in Variational Calculations of Atomic P-States
http://nur.nu.edu.kz:80/handle/123456789/4805
Expectation Values of Singular Operators in Variational Calculations of Atomic P-States
Shomenov, Toreniyaz
Expectation values of singular operators evaluated in the framework of the Rayleigh-Ritz
variational method in quantum mechanics may show slow convergence with increasing
the number of basis functions, K. An example of such commonly used operator in the
case of high-accuracy calculations of few-electron atoms and molecules is the Dirac delta
function dependent on interparticle distances, δ(rij). One way to improve the convergence
is to adopt the expectation value identities, in which the singular operator is replaced by
an certain non-singular operator so that the expectation value is the same in the limit
when the trial wave function approaches the exact solution to the Schrödinger equation.
However, when the wave function is approximate, which takes place for any finite K, the
convergence of the expectation value of this equivalent non-singular operator is usually
improved, often by orders of magnitude. In this thesis, we provide the derivation of
formulas for such expectation value identities and implement them into a computer code
for the case of atomic P-states, whose wave function is expanded in terms of all-particle
explicitly correlated Gaussian basis functions.
2020-05-05T00:00:00ZAnalysis of Individual Extensive Air Shower using Pulse Shape Information
http://nur.nu.edu.kz:80/handle/123456789/4804
Analysis of Individual Extensive Air Shower using Pulse Shape Information
Yessimbet, Kamilya
Study of Ultra-High energy Cosmic Rays (UHECR) coming to Earth from the deep
cosmos has the potential to open the veil on some remaining mysteries in the field
of High Energy Physics and Astrophysics. Horizon-T detector system is constructed
to study the nature of UHECR by means of studying its interactions with the Earth
atmosphere that result in so-called Extensive Air Showers (EAS). The detector system
is based at Tien Shan High-altitude Science Station (TSHSS) of P.N. Lebedev Physical
Institute of the Russian Academy of Sciences. It is located near the Almaty city,
Kazakhstan, at ∼ 3400 meter above the sea level. About 2000 EAS were selected
from the Physics Run 1 that has been detected during the period from January
2017 to April 2017 at Horizon-T detector system. The simulation activities indicate
the existence of the "invariant" property of the standard EAS as defined by the
CORSIKA simulator. In this work, I analyzed single-peaked EAS events in order
to use this property as a new approach to EAS data analysis using the fine time
resolution feature of Horizon-T detector. The definition of this invariant property,
its test using data and the classification of the EAS events from Physics Run 1 are
described in this thesis.
2018-04-23T00:00:00ZBrick-By-Brick: A Construction of ’t Hooft’s Brick Wall
http://nur.nu.edu.kz:80/handle/123456789/4796
Brick-By-Brick: A Construction of ’t Hooft’s Brick Wall
Gilman, Narynbek
A pedagogical construction and review, aimed at the undergraduate level, are given of the brick wall model. The brick wall is a finite region just outside the event horizon of a black hole. It is introduced in order to calculate the entropy of the collapsed star. The statistical origin of the entropy is still unknown, but the brick wall model offers an elementary exercise in counting quantum field solutions to arrive at the famous entropy-area result. The brick wall is a cut-off, effectively regularizing an otherwise divergent result. The model encompasses many fields of physics, including general relativity, quantum theory and statistical mechanics. Its multidisciplinary approach hints at what a more sophisticated solution will look like to the problem of a statistical explanation of the entropy of black holes.
2020-01-01T00:00:00Z