Field Source Research Articles

Thermodynamics of a newly constructed black hole coupled with nonlinear electrodynamics and cloud of strings

This paper finds an exact singular black hole solution in the presence of nonlinear electrodynamics as the source of matter field surrounded by a cloud of strings in 4DAdS spacetime. Here, the presence of the cloud of string, the usual Bardeen solution, becomes singular. The obtained black hole solution interpolates with the AdS Letelier black hole in the absence of both the deviation parameter and magnetic charge and interpolates with the AdS Bardeen black hole in the absence of the deviation parameter and a cloud of strings parameter. We analyse the horizon structure and thermodynamics properties, including the stability of the resulting black hole, numerically and graphically. Thermodynamical quantities associated with the black hole get modified due to the nonlinear electrodynamics and cloud of strings. Moreover, we study the effect of a cloud of strings parameter, magnetic charge and deviation parameter on critical points and phase transition of the obtained black hole where the cosmological constant is treated as the thermodynamics pressure. The critical radius increases with increasing deviation parameter values and magnetic charge values. In contrast, the critical pressure and temperature decrease with increasing deviation parameters and magnetic charge values.

Dynamics of Cultural Landscape on Idjen Boulevard as an Icon of Heritage Street Corridor in Malang City - Indonesia

The dynamic development of the city has brought about significant physical and environmental changes in Malang City, impacting the increasingly blurred identity of heritage areas. One such area is Idjen Boulevard, representing an icon of the heritage road corridor in Malang City. To comprehend the evolving nature of these heritage areas, it is essential to conduct studies documenting their past conditions and dynamics across various historical periods: the Colonial period, the Old Order period (the beginning of Indonesian independence), the New Order period, and the Reformation period. This comprehensive approach aims to understand the changes that occurred in each time periodization within each zone/road segment. These insights are crucial for determining future development control steps through targeted regulations. The research employs the Interpretive Historical Urban Landscape method, focusing on thirteen components that constitute the Cultural Landscape. This method involves analyzing the results of observations, both from literature and field sources, supported by tools such as CAD Mapper, Google Earth, Google Street View, GISTARU (an interactive urban spatial detail plan), and SketchUp. These tools are instrumental in obtaining findings about the hierarchy of changes in cultural landscape components and the dynamics within each zone of the specified observation unit.

Simulation of an operation of nested Halbach cylinder arrays in regenerative magnetic cooling cycles: The way to maximum thermal span

In this study, a numerical model of the Active Magnetic Regenerator (AMR) cycle, implemented in the reciprocal demonstrator, was developed using COMSOL Multiphysics. A nested Halbach cylinder (NHC) array served as the magnetic field source. Additional simulation of an operation of the NHC array was carried out. To eliminate the discrepancies between the heat exchange duration of the heat transfer medium (HTM) and the hot and cold ends of the regenerator, an adequate time dependence of the inner cylinder rotation angle was calculated. The latter provides the symmetrical sinusoidal form of time dependence of the magnetic flux density in the gap of NHC array, which is important for enhancing the performance of a magnetic refrigerator. It was established that in order to achieve a maximal temperature span, it is necessary to shift the phases of the magnetic field insertion/removal and heat transfer fluid pumping processes by nearly half of the operating cycle period. The latter brings the simulated cycle closer to the ideal AMR cycle.

Towards an EPR on a Chip Spectrometer for Monitoring Radiation Damage During X-ray Absorption Spectroscopy

AbstractElectron paramagnetic resonance (EPR) spectroscopy is an essential tool to investigate the effects of ionizing radiation, which is routinely administered for reducing contaminations and waste in food products and cosmetics as well as for sterilization in industry and medicine. In materials research, EPR methods are not only employed as a spectroscopic method of structural investigations, but also have been employed for detection of changes in electronic structure due to radiation damage from high energy X-rays, for example, to monitor radical formation inside biomolecules caused by X-ray irradiation at carbon, nitrogen, and oxygen K-edges at synchrotron facilities. Here a compact EPR spectrometer, based on EPR-on-a-chip (EPRoC) sensor and a portable electromagnet, has been developed as a solution for monitoring radiation damage of samples during their investigation by X-ray absorption spectroscopy (XAS) at synchrotron facilities. A portable electromagnet with a soft iron core and forced air temperature stabilization was constructed as the source of the external magnetic field. The sweep range of magnetic field inside the most homogeneous region of the portable electromagnet is 12–290 mT. The compact spectrometer performance was evaluated by placing the EPRoC sensor inside either a commercial electromagnet or the portable electromagnet to record the EPR spectrum of tempol, irradiated alanine, and dilithium phthalocyanine (Li2Pc). The potential performance of the portable spectrometer for the detection of radiation damage in organic compounds and transition metal-containing catalysts during XAS measurements in both fluorescence and transmission modes was calculated with promising implications for measurements after implementation in a synchrotron-based XAS spectrometer.

Resolution analysis of the gravity survey network in the middle and south sections of Tan-Lu fault and recent changes in the gravity field

In this paper, we computed the fractal dimension of three survey areas within the central and southern sections of the Tan-Lu fault zone using fractal analysis. Subsequently, simulations were conducted to analyze the gravity response under a forward model of equivalent density changes. Additionally, we thoroughly investigated the seismic monitoring capabilities of the gravity network in the central and southern regions of the Tan-Lu fault. Expanding on these analyses. Recent gravity field variations were examined in the mid-southern segment of the Tan-Lu fault zone and its surrounding areas from 2013 to 2023. The results indicate that the observation capabilities of the northern network in the study area outperform those of the southern gravity network, with the northern network demonstrating a more evenly distributed coverage. The optimal gravity anomaly recovery effect for the entire study area is achieved at a resolution of 0.5° × 0.5°. With an equivalent observable signal in the range of 30 × 10−8 m/s2 to 40 × 10−8 m/s2, the spatial resolution of the gravity network's field source is estimated to be approximately 55 km. From 2013 to 2023, a significant positive change has been observed in the gravity field within the study area. The Tan-Lu fault zone plays a crucial role in governing the crustal movement in this region, with the dextral strike-slip movement trend of the fault persisting. Small earthquakes occur more frequently in the southern section of the fault zone, while strong earthquakes are less common. The alignment of gravity field changes with the fault strike indicates ongoing activity in the fault zone without any signs of locking. In the central segment of the Tan-Lu fault zone in the Shandong region, there appears to be a weaker correlation between gravity field changes and fault trends. This discrepancy may suggest that the area is locked, resulting in the accumulation of stress and strain. It is imperative to monitor the continuous evolution of the gravity field in this region to gain insights into potential seismic risks.

Simulation study of a novel tensor CSAMT field source based on COMSOL

Simulation study of a novel tensor CSAMT field source based on COMSOL

Characterization of Neutron Irradiator as a Source of Reference Radiation Field for Calibrating Dosemeters and Doserate Meters at PSI Laboratory

A new neutron calibration laboratory has been installed at the Paul Scherrer Institute in Switzerland. The calibration laboratory has been equipped with a newly developed neutron irradiator with two calibration benches, remote control instruments and related ancillary equipment for calibrating dosemeters and doserate meters. The actual dimensions of the calibration laboratory are 2.0 m (H) X 6.8 m (W) X 12.6 m (L). On the steel grid at a height of 2 m from the basement floor, two calibration benches are installed. A transport channel is installed in the middle of the benches for the transfer of the radiation sources. The radiation sources are moved from the safe position of the irradiator to the reference irradiation position using an air pressure unit. The reference position is at a height of 1.2 m from the grid floor. The neutron irradiator is equipped with two Am-Be sources. Characterization of neutron radiation field has been calculated in detail by the MCNPX neutron transport code as well as energy distribution of neutrons and contribution of scattered neutrons. Experimentally, it was measured with a neutron/gamma digital spectrometric system equipped with a stilbene detector. The quality of the neutron radiation field has been characterized by ambient dose equivalent rate and the shape of the Am-Be spectra has been verified with the ISO-8529 standard.

Cooperative dynamic polaronic picture of diamond color centers

Polarons can control carrier mobility and can also be used in the design of quantum devices. Although much effort has been directed into investigating the nature of polarons, observation of defect-related polarons is challenging due to electron-defect scattering. Here we explore the polaronic behavior of nitrogen-vacancy (NV) centers in a diamond crystal using an ultrafast pump-probe technique. A 10-fs optical pulse acts as a source of high electric field exceeding the dielectric breakdown threshold, in turn exerting a force on the NV charge distribution and polar optical phonons. The electronic and phononic responses are enhanced by an order of magnitude for a low density of NV centers, which we attribute to a combination of cooperative polaronic effects and scattering by defects. First-principles calculations support the presence of dipolar Fröhlich interaction via non-zero Born effective charges. Our findings provide insights into the physics of color centers in diamonds.

Feature selection before propositionalization of multi-source oil drilling data

Despite recent improvements in collected drilling data quality and volume, the actual number of wells being used in studies remain low and are often limited to a single source and oil field, producing results that are prone to overfitting and are non-transferable. In our study, we access oil drilling data from 5 of more than 20 oil drilling companies collected from 2005 to 2016 from our industrial partner to create well drilling duration models for well planning. This project could lead to the creation of more generalized models from larger datasets than others in literature. However, the data is difficult to process without expert knowledge, further complicated by properties such as unharmonized, source-locked, semantic heterogeneity, sparse and unlabelled. Conventional automated methods for feature selection, propositionalization, multi-source, or block-wise missing techniques could not be used. In this paper, we describe our method to assist the Knowledge Discovery in Databases (KDD) Selection stage of the abovementioned data - Feature Selection before Propositionalization (FSbP) via Database Attribute Health Feature Reduction (DAHFR) and Report Feature Correlation Matrix (RFCM), collectively known as FvDR. DAHFR and RFCM are filter-type feature selection techniques that could measure relational missingness and keyword correlations respectively despite the complexity of multi-source oil drilling data. FvDR successfully reduced the scope from 700 tables containing 20,000 columns to 22 tables containing fewer than 707 columns while successfully selecting 13 of 16 relevant tables suggested by literature. Despite the loss of information from limitations of subsequent KDD procedures, preliminary models show promising results with over half the test predictions falling within the 20% error margin required for well planning. FvDR proves to be indispensable in KDD as a FSbP framework as it reduces features for examination and streamlines the research process necessary to understand business rules for data harmonization and propositionalization.

Imprints of dark matter on the structural properties of minimally deformed compact stars

In this manuscript, we investigate the possibility of constructing anisotropic dark matter compact stars motivated by the Einasto density profile. This work develops analytical solutions for an anisotropic fluid sphere within the framework of the well-known Adler–Finch–Skea metric. This toy model incorporates an anisotropic fluid distribution that includes a dark matter component. We use the minimal geometric deformation scheme within the framework of gravitational decoupling to incorporate anisotropy into the pressure profile of the stellar system. In this context, we model the temporal constituent of the Θ-field sector to characterize the contribution of dark matter within the gravitational matter source. We present an alternative approach to studying anisotropic self-gravitating structures. This approach incorporates additional field sources arising from gravitational decoupling, which act as the dark component. We explicitly verify whether the proposed model satisfies all the requirements for describing realistic compact structures in detail. We conclude that the modeling of the Einasto density model with the Adler–Finch–Skea metric gives rise to the formation of well-behaved and viable astrophysical results that can be employed to model the dark matter stellar configurations.

Some cases of explicit expression of the resulting field strength of magnets placed in the field of external sources

Formulas for calculating of the resulting magnetic field strength of magnets with a given magnetization distribution or given field of external sources are presented. We have collected exactly those cases where a user who does not have much experience in the field of computational mathematics and programming can perform calculations using these formulas. Namely, in these cases formulas for tension are mostly expressed in final form through elementary functions or require the use of one of the standard subroutines available in the library of any programming language. Such formulas can serve both as reference material and for solving corresponding problems with suitable real objects, as well as for determining optimal strategies and the optimal set of input parameters when using universal software packages and assessing the error of the results obtained.

A flexible solid-state asymmetric supercapacitor device comprising cobalt hydroxide and biomass-derived porous carbon.

Development in the field of alternative and renewable energy sources is becoming necessary considering the current energy demands of the growing technologies. The main challenge associated with the produced energy is to store it for future use, such that it can be used when needed. Supercapacitors are among the electrochemical energy storage systems that provides higher power density, faster charging-discharging, high specific capacitance (C S), and long cycling life. Herein, the fabrication of a flexible solid-state asymmetric supercapacitor (ASC) device is reported, where Co(OH)2 hollow spheres and biomass-derived porous carbon (PC) are the cathode and anode, respectively. Co(OH)2 is a highly redox active material, whereas PC is an electric double-layer capacitive (EDLC) material. In this device, aqueous KOH solution (electrolyte) encapsulated in PVA gel (separator) was used to bind the electrodes. This Co(OH)2//PC ASC device exhibited a high C S of 260 F g-1 (at 2 A g-1). It retained ∼91% of the initial C S value (at 6 A g-1) till ∼5000 cycles. Electrochemical impedance spectroscopy (EIS) study confirmed low internal resistance (0.95 Ω) and charge transfer resistance (1.41 Ω) values of Co(OH)2//PC. These results indicate that the high electron transfer process in the electrode-electrolyte interface during the electrochemical reaction, which is responsible for the excellent performance of this ASC device. The high-performance Co(OH)2//PC ASC device exhibited an energy density of 76.7 W h kg-1 at a power density of 1416.9 W kg-1. To demonstrate its practical use, LED lights were illuminated using this Co(OH)2//PC ASC device.

Simulations of the optical diffraction patterns produced by the pressure field of a clinical shock wave source

Today, shock waves are used to treat a wide variety of ailments. Consequently, there is a need to develop efficient methodologies for comparing and evaluating the pressure fields generated by different equipment. Hydrophones are commonly utilized for accurate pressure measurements although they can be damaged by pitting due to acoustic cavitation. Furthermore, the range of measurement is limited by the position of the device. Optical methods have also been proposed since the presence of a disturbing device in the wave propagation medium is not necessary, and they provide a broader registering field. Nevertheless, these methods do not provide accurate measurements compared with those obtained with polyvinylidene difluoride or fiber-optic hydrophones. Herein, an optical method for shock wave characterization based on diffraction analysis, that can lead to more precise results, is proposed. The phase fluctuations of a light wave produced when it traverses the shock wave pressure field are calculated. The diffraction patterns produced by this perturbed wave at an observation plane at different propagation distances are presented. Considering the state of the art of high-speed cameras, we conclude that an experimental setup, based on the results reported here, can contribute to the evaluation and comparison of shock wave generators for medical applications.

Cellulose-reinforced foam-based phase change composites for multi-source driven energy storage and EMI shielding

To address the increasingly serious environmental pollution and energy crisis, there is an urgent need to develop multi-source-driven energy storage materials, the field of new energy sources, such as solar thermal power generation, but electromagnetic pollution has become a primary problem that needs urgent resolution. Therefore, the development of multifunctional phase change composites (CPCMs) with multi-source drive capabilities and excellent electromagnetic shielding integration is crucial. In this study, polypyrrole (PPy)-coated conductive fibers were crosslinked with polyvinyl alcohol (PVA) to form a three-dimensional network, which was then combined with metal foam to prepare Ni–F/PPy@CNF-PVA (PCN) dual-network carriers with high electrical conductivity by vacuum-assisted adsorption and freeze-drying methods. Polyethylene glycol (PEG) was subsequently encapsulated via vacuum impregnation to get the shape-stable PEG/Ni–F/PPy@CNF-PVA (PPCN) phase change composites. The PPCN exhibited good stability and high energy storage density (melt enthalpy up to 126.18 J/g, relative enthalpy efficiency over 99 %). Benefiting from its outstanding electrical conductivity (186680 S/m for PPCN-3), light-absorbing properties, and magnetism, the PPCN also exhibits highly efficient photothermal, electrothermal, and magnetothermal conversion capabilities. The electromagnetic interference shielding efficiency reaches up to 110.37 dB within the X-band frequency range (8.2–12.4 GHz). In conclusion, PPCNs are significant for multi-source-driven energy storage and electromagnetic shielding.

State Policy In The Field Of Alternative Energy Sources In The Conditions Of Ensuring Energy Security Of Ukraine

The article analyses features of state policy in the field of alternative energy sources, particularly replacing traditional energy resources with alternative energy sources, aiming to reduce the energy intensity of Ukraine’s gross domestic product and ensure the state’s energy security. It is noted that Ukraine has significant potential for developing alternative energy sources, particularly wind energy, solar energy, bioenergy, hydropower, and geothermal energy. An analysis of the growth dynamics of the installed capacity of alternative energy source facilities operating under the «green» tariff has shown that solar energy is currently the most developed in Ukraine. This creates a foundation for further development of wind and bioenergy. The main practical benefits of energy storage systems are highlighted, including ensuring electricity supply to businesses when the external grid is disconnected, storing cheap electricity during excess capacity, and supplying it during peak demand when it is more expensive. Additionally, these systems have the potential to support and restore grid frequency. Storing surplus energy from solar power plants can increase the overall efficiency of the energy system. The author identifies the main tasks to be implemented within state policy to ensure energy security. These include investing in the restoration and decentralization of the energy system (increasing the share of electricity production from alternative energy sources, including the construction of wind and solar power plants, as well as energy storage facilities for the development of energy storage technologies produced from renewable sources), building biomethane production capacities, introducing new types of environmentally friendly fuels, increasing the construction of interconnectors with ENTSO-E to integrate Ukraine’s electricity system with the European power grid, enhancing the localization of energy storage systems, implementing innovative and efficient technologies in the electricity distribution sector, including smart grids, microgrids, and «vehicle-to-grid» systems, and resolving issues related to the «green» tariff.

Correlation Iteration Method of Acoustic Tomography with Incoherent Field Sources

Correlation Iteration Method of Acoustic Tomography with Incoherent Field Sources

Semantic field SEARCH in Amguema Chukchi: From morphosyntax to semantics and back

The study describes the semantic field of search in Amguema Chukchi within the frame-based approach to lexical typology. I discuss lexical items of the macroframe of seeking an object (‘search for something’): the verb qərirək and the lexical affixes ‑rerək and ‑ɣiɬik; verbs of the macroframe of searching space (‘search some place’): ojpətkok и rəritɬʔewək; and the verb enarerək, which covers both macroframes and can also describe objectless search. In addition to unveiling semantic oppositions within each macroframe, the study examines in detail the interaction of morphosyntax, etymology, and semantics of the items of the field. First, a historical explanation is provided for the properties of the verb enarerək, unique with respect to valency expression, which yields its broad semantics. The explanation is based on the historical presence of the antipassive prefix in this verb and, at the same time, on the fact that this voice alternation has been lost in the Amguema dialect. Secondly, differences in the behavior of independent lexemes and lexical affixes that compete in the macroframe of searching for an object are considered. I conclude that there is a correlation between the referentiality of the searched object and the degree of boundedness of the morpheme with the meaning ‘to search’. Noticeably, the correlation within the semantic field of search manifests itself in the form of combinability restrictions that are not obligatory for independent verbs or lexical affixes outside the field. Thirdly, for the macroframe of searching space, I trace the transmission of semantic restrictions on combinability from the source field.

Analyzing the 3D-MHD flow of a sodium alginate-based nanofluid flow containing alumina nanoparticles over a bi-directional extending sheet using variable porous medium and slip conditions

Abstract The sodium alginate (SA)-based nanofluid flow comprising alumina nanoparticles on a bi-directional extending sheet has many applications, which include thermal management, automotive radiators, industrial heat exchangers, conductive coatings, flexible electronics, electromagnetic shielding, solar panels, etc. A numerical study based on the SA-based nanofluid flow containing alumina nanoparticles over a bi-directional extending sheet in the presence of variable Darcy porous media has not yet been examined. Therefore, this study focuses on numerically investigating the flow behavior of a nanofluid of SA containing nanoparticles of alumina (Al2O3) over a bi-directional extending sheet. The variable Darcy porous media, magnetic field, thermal radiation, and thermal-dependent and space-dependent heat sources are applied to examine heat transfer flow. The velocity and thermal slip conditions have been used in the present model. The model is first shown as partial differential equations and is then converted to ordinary differential equations (ODEs). A numerical technique called bvp4c MATLAB function is applied to solve the modeled ODEs. The model is validated with previously published results. From the obtained results, it is found that high magnetic factor increases the thermal distribution, skin frictions, and heat transfer rate and reduces the velocity profiles along both directions. The Casson factor reduces the skin friction, heat transfer rate, and velocity profiles along both directions while increasing the thermal distribution. High velocities and temperature distributions of a SA-based nanofluid flow containing alumina nanoparticles are found for the scenario of no-slip condition when matched to the slip condition. It is concluded from the observed results that the percentage increase is higher for the no-slip conditions compared to the slip conditions.

Anti-Russian sanctions in the domestic oil and gas industry: problems and prospects

The relevance of the topic of the scientific article is determined by a number of circumstances related to the fact that the oil and gas industry is one of the main sectors of the Russian economy, as well as an important component of domestic exports. The sanctions of Western countries on the economy of the Russian Federation have had a noticeable impact on the operating conditions of the industry and the requirements imposed on it by the world and the national economy. The article formulates the challenges facing the industry, which is under sanctions, and shows the possibilities of its development in 2024 and in the future. According to the author, the effectiveness of industry management, improvement of technologies, logistics, as well as the search for non-traditional sales markets are of fundamental importance today. The purpose of the article is to identify the problems of the domestic oil and gas industry that arose in the sanctions conditions, to identify realistic directions for its development. The subject of the study is the hydrocarbon industry of the Russian Federation, the object of the study is changes in the domestic energy sector under the influence of Western sanctions. The article used analytical, comparative, empirical methods and visualization. It is shown that along with the development of traditional energy in the Russian Federation, it is important to pay close attention to the intensification of activities in the field of renewable energy sources. A number of measures have been proposed to reduce the negative impact of sanctions on the hydrocarbon segment of the domestic economy.

Simplified Model of the Solar Magnetic Field

This paper considers a structure consisting of two rings of magnetic dipoles symmetrical relative to the equatorial plane as a possible model for the source of the solar magnetic field. It shows that the magnetic field generated by this structure corresponds to Joy’s law and Hale’s polarity law. Approximate calculations show that the form and shape of the equatorial field of this structure are close to measured values, and the resulting distribution of sunspots is in agreement with Joy's law to Maunder’s butterfly diagram. Based on this structure, it is possible to explain the appearance of two peaks (Gnevyshev gap) in the distribution of sunspots at the maximum of solar activity. Calculating the polar field based on the principles of magnetic hysteresis shows a good coincidence of the calculated and measured values and makes it possible to predict the behavior of the polar field in the interval to the nearest minimum of solar activity. Analyzing dipole nutation makes it possible to predict the intensity of the upcoming solar activity maxima, while a nutation period of approximately 8 months can be associated with 1.3 yr-period field oscillations. Despite the fact that the emergence and the functioning of the proposed configuration of magnetic dipoles is considered in a simplified manner and only from the point of view of gyromagnetic and thermal forces for speed and clarity, this does not limit the use of the proposed structure as a potential model in other, more global-scale general hydromagnetic theories of solar magnetism.