Roskilde University
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Publications
6 903
Citations
166 001
h-index
148
Top-3 journals
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Lecture Notes in Computer Science
(139 publications)
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Journal of Chemical Physics
(132 publications)
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Ethical Economy
(55 publications)
Top-3 organizations
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University of Copenhagen
(896 publications)
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Aarhus University
(395 publications)
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Technical University of Denmark
(363 publications)
Top-3 foreign organizations
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Lund University
(83 publications)
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University of Gothenburg
(62 publications)
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University of Oslo
(56 publications)
Most cited in 5 years
Found
Publications found: 106
Some norm estimates for the triangular projection on the space of bounded linear operators between two symmetric sequence spaces
Tomskova A.
For two given symmetric sequence spaces E and F we study the action of the main triangular projection T on B(E, F), the space of all bounded linear operators from E to F, and give a lower estimate for the norm of T in terms of the fundamental functions of E and F and the fundamental function of the generalized dual space F : E. In addition, we give a condition for the boundedness of the operator T in terms of F-absolutely summing operators. Furthermore, we apply our results to some concrete symmetric sequence spaces. In particular, we study the question of the boundedness or unboundedness of T on the spaces $$B(\ell _{p_1,q_1},\ell _{p}),$$ $$B(\ell _{p},\ell _{p_1,q_1})$$ and $$B(\ell _{p_1,q_1},\ell _{p_2,q_2})$$ .
Weak gravitational lensing around dyonic ModMax black hole in plasma
Turakhonov Z., Atamurotov F., Ovgun A., Abdujabbarov A., Urinov S.
Abstract
In this study, we examine the effects of weak gravitational lensing and determine the shadow radius around black holes within the Dyonic ModMax (DM) spacetime, also accounting for models with nonuniform plasma distributions. By analyzing various gravitational lens models, we compare corrections to vacuum lensing due to gravitational effects within plasma and plasma inhomogeneity, finding that these effects could be observed in hot gas within galaxy clusters. Starting with the orbits of photons around a black hole in DM, we investigate the shadow and weak gravitational lensing phenomena. Utilizing observational data from the Event Horizon Telescope (EHT) for $M87*$ and $SgrA*$, we constrain parameters within DM gravity. To connect our findings to observations, we examine the magnification and positioning of lensed images, along with the weak deflection angle and magnification for sources near different galaxies.
Integrating Cloud, Blockchain and AI Technologies—Challenges and Scope
Ahuja L., Thakur A., Seth A., Seth K.
An organization’s particular demands and objectives, as well as the kind of projects or initiatives the businesses are pursuing, will determine whether to integrate cloud computing, blockchain, and artificial intelligence (AI). Combining blockchain’s data integrity, AI’s analytics, and cloud computing’s scalable storage and processing can offer a holistic solution for storing, analysing, and safeguarding data if a business deals with enormous volumes of data from diverse sources. Supply chain management, health care, and finance are a few sectors that can benefit from the integration of blockchain’s immutability, cloud security measures, and AI’s anomaly detection. These sectors also demand high levels of security, transparency, and trust. Even if the integration has many advantages, it is critical to take into account the complexity, resource needs, costs, and potential difficulties connected with integrating cloud, blockchain, and AI in your specific environment. This paper examines the potential effects of combining these three technologies.
Neutrino oscillations in the Non-Kerr black hole with quantum phenomenon
Alibekov H., Atamurotov F., Abdujabbarov A., Khamidov V.
Abstract
In this study, we have investigated the mathematical components of the Dirac equation in curved spacetime and how they can be applied to the analysis of neutrino oscillations. More specifically, we have developed a method for calculating the phase shift in flavor neutrino oscillations by utilizing a Taylor series expansion of the action that takes into account
orders. In addition, we have used this method to assess how the phase difference in neutrino mass eigenstates changes according to the gravitational field described by the Johannsen spacetime.
Method for the determination of electron density from multi-energy X-ray CT
Jumanazarov D., Alimova A., Ismoilov S.K., Atamurotov F., Abdikarimov A., Olsen U.L.
We propose a method for estimation of material's electron density parameter (ρe) using multi-energy x-ray Computed Tomography (CT). Multi-energy CT uses a photon counting detector (PCD) to measure a material's linear attenuation coefficient (LAC) at multiple energies with the simultaneous data acquisition. The physical effects in the PCD such as charge sharing and photon pileup result in spectral distortions of the energy spectrum. Corrects for such distortions are performed with a correction algorithm. A custom laboratory instrument for multi-energy CT is used to experimentally validate the method. The identification efficiency is evaluated for different numbers of energy channels. When using 15 energy channels without inter-gaps the method gives a relative deviation of 1.8% for estimation of ρe, for materials in the range of 0.43≤ρe≤1.06e−mol/cm3.
Forecasting Smart Grid Stability Using a Hybrid CNN Bi-LSTM Approach
Singhal D., Ahuja L., Seth A.
The prediction of smart grid stability is paramount for identifying contributors to network instabilities, yet it remains a challenging endeavor. To predict the stability of smart grid systems, researchers offer a novel method in this paper that uses a hybrid Convolutional Neural Network Bidirectional Long Short-Term Memory (CNN Bi-LSTM) model. By combining CNN's capacity to extract spatial characteristics with Bi-LSTM's capacity to record temporal dependencies, the suggested method overcomes the drawbacks of earlier techniques and provides a complete stability prediction solution. The research uses data transformation and normalization techniques to analyze data efficiently. To ensure fair handling of data, min–max normalization is utilized to reduce biases resulting from the Smart Grid database’s predilection for high-importance entries. This normalization process enhances algorithmic effectiveness by standardizing data sizes. The data analysis process begins with thorough exploration, allowing users to flexibly uncover preliminary patterns, primary points of interest, and distinctive attributes within the sizable dataset. Leveraging the Convolutional Neural Network framework, features are extracted, and the dimensionality problem stemming from the expanding smart grid systems is addressed using a principal component analysis-based feature selection technique. Finally, we introduce a novel Bidirectional Long Short-Term Memory technique tailored specifically for forecasting smart grid network stability. The proposed approach achieves superior accuracy, boasting a remarkable 96.9% accuracy rate compared to existing methods. This hybrid CNN Bi-LSTM methodology not only improves prediction accuracy but also enhances our understanding of smart grid dynamics, paving the way for more reliable and efficient energy management systems.
Quasi-periodic oscillations and particle motion around charged black hole surrounded by a cloud of strings and quintessence field in Rastall gravity
Ashraf A., Ditta A., Sofuoğlu D., Ma W., Javed F., Atamurotov F., Mahmood A.
Abstract
This work mainly focuses on unveiling the particle dynamics features of black holes. For this objective, we utilize the charged black hole geometry consisting of the cloud strings and quintessence under the ansatz of Rastall gravity. We have calculated and analyzed the effective potential, angular momentum, particle energy, horizon radius, inner stable circular orbit, photon sphere radius, quasi-periodic oscillations, and effective force to reveal the dynamical features. We in detail discussed the effects of charge in black hole, Rastall parameter, strings of cloud parameter, and quintessential parameter on the calculated results. To ensure the scenario of accelerated expansion, ω
q
lies in the range −1 < ω
q
< −1/3. From this specific range, we choose ω
q
= −2/3.
Joule-Thomson expansion of Bardeen black hole with a cloud of strings
Yasir M., Tiecheng X., Ditta A., Arora D., Atamurotov F., Mahmood A., Egamberdiev O.
This study focuses on the newly suggested Bardeen BH concept with a cloud of strings around it. Isenthalpic curves in the [Formula: see text] plane are explored concurrently with the investigation of the Joule–Thomson coefficient and inversion temperature. A comparison between the behavior of the BH and the Van der Waals fluid is made in order to shed light on the system and clarify its similarities and differences. A crucial component of our research entails determining corrected entropy in order to comprehend thermal fluctuations. Based on corrected entropy, the thermal stability debate shows that there is no fluctuation when it comes to small BHs. Additionally, we investigate the energy emission process from the Bardeen BH solution with a cloud of strings in order to clarify this important thermodynamic feature.
Trade credit and firm value in business groups: evidence from Korea
Kim W.S., Lee S.H., Lee K.J., Park K.
Q3
Asia-Pacific Journal of Accounting and Economics
,
2024
,
citations by CoLab: 0
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Formation mechanism of decay fragments in spontaneous ternary fission of heavy nuclei
Kalandarov S.A., Tashkhodjaev R.B., Ganiev O.K.
Q1
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
,
2024
,
citations by CoLab: 0
,
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Open Access
|
Abstract
A model for describing spontaneous ternary fission of heavy nuclei is presented. It follows from the suggested model that heavy nuclei have the same half-lives in spontaneous ternary and binary fission processes. The collinear cluster tripartition process observed in FOBOS experiments is found to be the dominant reaction channel in spontaneous true ternary fission of heavy nuclei within our model. Competition between binary fission and the formation of a trinuclear system, which is responsible for the ratio of spontaneous ternary and binary fission yields, is introduced.
Exploring the Shadow of a Rotating Charged ModMax Black Hole
Karshiboev K., Atamurotov F., Abdujabbarov A., Ovgun A., Reyimberganov A.
Abstract
The research presented in this paper discusses the impact that the parameters of charge (Q) and screening factor (γ) have on properties of the horizon and silhouette of rotating charged ModMax black holes which were reviewed in [Eur.
Phys.
J.
C (2022) 82:1155] recently, building upon previous findings in the field. Furthermore, the study explores the behavior of null geodesics, which can help us better understand the apparent shape of the black hole’s silhouette, as well as the distortion parameter and approximate radii of the silhouette that are influenced by the aforementioned parameters, and there are some values of parameter Q which corresponds to data from the Event Horizon Telescope (EHT). Notably, we explore the distortion parameter and approximate radii of the silhouette, revealing that while an increase in γ leads to a growth in silhouette radius (R
s
), it simultaneously reduces the distortion rate (δ
s
). Conversely, heightened Q charge results in a reduction of R
s
accompanied by an increase in δ
s
. Lastly, the paper analyzes the effects of the black hole’s parameters on the effective potential and energy emission: the peak value of the energy emission rate experiences a decrease as the screening factor (γ) increases, while it increases with higher values of the charge parameter (Q).
Gravitational weak lensing of hairy black hole in presence of plasma
Atamurotov F., Yunusov O., Abdujabbarov A., Mustafa G.
Gravitational weak lensing around a hairy black hole has been deeply studied in the presence of a plasma medium. The obtained results have shown that the effect of parameters a and l0 on the deflection angle of light rays around the black hole in hairy spacetime is perceptible. With an increase of parameter a the deflection angle of photon orbits decreases, and the effect of plasma on the deflection angle is the opposite. Here, we discussed different types of plasma distributions: uniform ωe=const, Singular Isothermal Sphere medium, 1/r and Non-Singular Isothermal gas sphere plasma. Additionally, The total magnification of the image source due to gravitational lensing has been also studied taking into account the effect of deviation parameter a and parameter l0 related to hairy spacetime in the presence of plasma around the black hole.
Weak gravitational lensing of black hole from T-duality in plasma
Orzuev S., Atamurotov F., Abdujabbarov A., Abduvokhidov A.
In this study, we investigate the impact of a plasma environment on gravitational weak lensing around a black hole from the perspective of T-duality. Our results demonstrate that the deflection angle of light rays around the black hole is notably affected by the parameter l0, with an increase leading to a decrease in the deflection angle, while the effect of plasma on the deflection angle is the opposite. We also consider different types of plasma distributions, including uniform ωe=const, Singular Isothermal Sphere medium, and Non-Singular Isothermal gas sphere plasma. We have analyzed the total magnification of the image source due to gravitational weak lensing, taking into account the effect of parameter l0 related to T-duality in the presence of plasma around the black hole.
Thermodynamical analysis of acoustic Schwarzschild black hole
Yasir M., Tiecheng X., Ditta A., Ali R., Atamurotov F.
In this paper, we analyze the thermodynamic properties of acoustic Schwarzschild black holes with its parameter. The study is conducted in the extended phase space displaying the phase transition. This phase transition is examined through Gibbs free energy, specific heat, and heat capacity. Later, we discuss the thermal stability of acoustic black holes through Hawking temperature by identifying their stable and unstable regions. We calculate the corrected entropy to examine the thermal fluctuations. Through the corrected entropy we observe that there is no fluctuation in the case of small black holes. We also discuss the energy emission process from acoustic black holes. Moreover, we employ the generalised uncertainty principle to obtain a modified Lagrangian equation. We analyse the tunneling and Hawking temperature of the acoustic Schwarzschild black hole after solving the field equations.
Long-term Lease on Waqf Lands in Khorezm: A New Form of Privileges of Sacred Lineages
Yakubov Q.
Abstract
The aim of this paper is to examine the mechanism of long-term lease on religious endowment (waq f) lands in Khorezm. In particular, the primary focus of the present study is twofold. Firstly, it investigates the practice of long-term lease on waq f lands on the basis of rental contracts, as well as other concomitant records from 19th-century Khorezm. Secondly, this study examines the social background of and reciprocal relations between participants, who were involved in long-term lease operations. As becomes evident from the documents under study, the family members of Muḥammad Šarīf Īšān, a prominent figure of the Naqshbandiyyah-Mujaddidiyyah in Khorezm, acted in the capacity of trustee (mutawallī) of waq f properties of the Sayyid Muḥammad Raḥīm Ḫān’s madrasa in Khiva, regularly commissioned and financially supported by the ruler himself, as well as other representatives of the Qonghrat dynasty (1770-1920). Moreover, members of Muḥammad Šarīf Īšān’s family also participated as tenants of occasionally large waq f assets in long-term lease contracts. To this end, this study posits that the employment of long-term lease practice on waq f land was a principal means of providing financial support by the Khivan ruling circles to various Sufi lineages in Khorezm. Thus, the long-term lease operation clearly illustrates yet another pattern of patronage between the ruling dynasty and descendants of a particular Sufi lineage, as well as an additional source of income and financial privilege of the latter.
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