Theoretical Estimates Research Articles

ASYMPTOTIC PROPERTIES OF PARAMETRIC EIGENVALUE PROBLEMS IN THE HILBERT SPACE

The parametric eigenvalue problem in infinite-dimensional Hilbert space arising in the mechanics of loaded thin-walled structures is investigated. Asymptotic properties of solutions depending on loading parameters are established. The initial infinite-dimensional problem is approximated in a finitedimensional subspace. Theoretical error estimates of approximate solutions are obtained. Effective numerical methods for calculating the main resonance frequency and the corresponding resonance form of vibrations based on asymptotic formulas are proposed.

Reflectionless Filtering Power Divider with Wide Passband Using LTCC Technology

Abstract This paper presents a reflectionless filtering power divider (FPD) in low-temperature co-fired ceramic (LTCC) technology. The proposed FPD consists of a pair of parallel-coupled lines (PCLs), an absorptive bandstop filtering (ABSF) section and a Wilkinson power divider section, which are distributed in different LTCC layers. A controllable wide passband is realized by quarter-wavelength PCLs and reflectionless performance at the out-of-band is achieved by employing a lossy resistor loaded in the ABSF section. For demonstration, a prototype of the proposed FPD operating at 6.5 GHz with a 3-dB fractional bandwidth of 60% is designed and fabricated using LTCC. The measured results are in good agreement with the simulated ones, which validates the theoretical prediction and design idea.

Excited states from GW/BSE and Hartree-Fock theory: Effects of polarizability and transition type on accuracy of excited state energies.

GW and Bethe-Salpeter equation (BSE) methods are used to calculate energies of excited states of organic molecules in the Quest-3 database [Loos et al., J. Chem. Theory Comput. 16, 1711 (2020)]. The self-energy in the GW approximation is conventionally calculated using the RPA polarizability. Inclusion of a screened electron-hole interaction in the polarizability was recently shown to improve predictions of experimental ionization energies in organic molecules [C. H. Patterson, J. Chem. Theory Comput. 20, 7479 (2024)]. Self-energies from RPA or screened time-dependent Hartree-Fock (TDHF) polarizabilities in the GW/BSE method are used to calculate 141 singlet excited states in Quest-3. Theoretical best estimate excited state energies from the CC3 coupled cluster method and aug-cc-pVTZ basis sets are used to benchmark GW/BSE and CIS calculations using the same molecular geometries and basis sets. Differences between GW/BSE or CIS excited state energies and best estimate values show that there are systematic variations in the accuracies of excited state energies classified as ππ*, nπ*, πR (Rydberg), or nR character. The origin of these variations is the accuracy of self-energies of states of nonbonding vs π bonding character. In particular, N or O lone pair states require large self-energy corrections owing to strong orbital relaxation in the localized hole state, while π states have smaller corrections. Self-energies from a screened TDHF vs RPA polarizability are typically over(under)estimated for nonbonding states, leading to under(over)estimation of energies of excited states of nπ* or nR character.

Convergence Analysis of a Nonconforming Virtual Element Method for Compressible Miscible Displacement Problems in Porous Media

ABSTRACTThis article presents a priori error estimates for the miscible displacement of one compressible fluid by another in a porous medium. The study utilizes the conforming virtual element method (VEM) for the approximation of the velocity, while a non‐conforming virtual element approach is employed for the concentration. The pressure is discretized using the standard piecewise discontinuous polynomial functions. These spatial discretization techniques are combined with a backward Euler difference scheme for time discretization. Error estimates are established for velocity, pressure, and concentration. The article also includes numerical results that validate the theoretical estimates.

Interrelationship between Multichannel Sound Formats and the “Embodiment” in Cinema

The article investigates the connection between the use of multichannel sound formats and the development of film theory: in particular, the ability of surround sound to “immerse” the viewer in the narrative universe, evoking proprioceptive sensations with sound which gives a new impetus to the theory of “embodiment” developing in the paradigm of phenomenological aesthetics. New sound films not only put the viewer into a new acoustic environment, but also create parallel universes represented by sound and identified by the viewer as “material”, capable of not only causing a reaction, but also “finalizing” the image in the minds of viewers. Technological innovations in sound recording and sound reproduction due to the introduction of multichannel systems have led to the transformation of auditory perception and the emergence of an entirely new type of acoustic space. With film sound becoming more multi-layered and omnidirectional, the auditory component has been elaborated with synthesized textures as a result of sound design. The aesthetic potential and expressiveness of the “format” sound has broken a new ground in the progress of virtual reality in film and affected the viewer’s artistic perception of the latest works of screen art as well as the development of new theoretical ideas.

Bound-State Beta Decay of Tl20581+ Ions and the LOREX Project

Stable Tl205 ions have the lowest known energy threshold for capturing electron neutrinos (νe) of Eνe≥50.6 keV. The Lorandite Experiment (LOREX), proposed in the 1980s, aims at obtaining the longtime averaged solar neutrino flux by utilizing natural deposits of Tl-bearing lorandite ores. To determine the νe capture cross section, it is required to know the strength of the weak transition connecting the ground state of Tl205 and the 2.3 keV first excited state in Pb205. The only way to experimentally address this transition is to measure the bound-state beta decay (βb) of fully ionized Tl81+205 ions. After three decades of meticulous preparation, the half-life of the βb decay of Tl81+205 has been measured to be 291−27+33 days using the Experimental Storage Ring (ESR) at GSI, Darmstadt. The longer measured half-life compared to theoretical estimates reduces the expected signal-to-noise ratio in the LOREX, thus challenging its feasibility. Published by the American Physical Society 2024

Вплив структурних факторів на характеристику пластичності

The main theoretical standson the plasticity characteristic, which is determined by the proportion of plastic deformation in the total defo stands rmation and characterizes the ability of the material to undergo plastic deformation, were developed by Profes-sor Yu. V. Milman. This article is devoted to the experimental verification of theoretical statements about the influence of structural factors on the plasticity characteristic, which can be determined from measurements of hardness (H) and during standard mechanical tests (*). The study was performed on materials with different levels of plasticity (ARMCO–Fe, aluminum alloys AMg5, 7075 and monocrystalline silicon). ARMCO-Fe and aluminum alloy 7075 have different plasticity, but in the investigated range of grain change values (ARMCO–Fe d = 20—550 μm, aluminum alloy 7075 d = = 4—60 μm), the dependence of the plasticity characteristic on d is linear. ARMCO-Fe and aluminum alloy 7075 have different plasticity, but within the investigated range of grain sizes (ARMCO-Fe: d = 20—550 µm, aluminum alloy 7075: d = 4—50 µm), the change in plasticity characteristics in regard to grain size has linear dependences. The resulting dependences of the plasticity characteristic H and * on structural factors showed that a decrease in the grain size and an increase in the density of dislocations, which increase the yield strength of the material, lead to a decrease in the plasticity characteristic. The comparison of experimental data with theoretical ideas about the influence of structural factors on the plasticity characteristic showed a satisfactory match between the theory and the experiment (which will impact to the further development of the theory of the dependence of plasticity on other structural and external factors). Keywords: mechanical properties, plasticity, structure, dislocation density.

Review on Oral Osmotic Tablet

Traditional oral medication delivery methods provide the drug with an immediate release and an efficient concentration at the intended location. Such a dosage regimen could lead to unexpected, ever-changing plasma concentrations. As a result, numerous regulated medication delivery systems are created. Among these, osmotic drug delivery systems (ODDS) and pulsatile drug delivery systems (PDDS) are becoming more and more significant because they improve patient treatment efficacy and compliance by delivering the medicine at precise times based on the course and physiological requirements of the disease. They regulate the drug’s delivery by using the osmotic pressure theory.To a significant extent, the drug’s release is unaffected by GIT physiological variables. Both targeted and systemic medication delivery are possible with these methods. The theoretical idea of drug delivery, various oral osmotic drug delivery system types, factors influencing the drug delivery system, benefits and drawbacks of these delivery systems, fundamental osmotic system components, evaluation parameters, difficulties, and emerging technologies in oral controlled drug delivery are all “highlighted” in this review.

Optimal Feedback Rate for Multi-Antenna Maximum Ratio Transmission in Single-User MIMO Systems with One-Bit Analog-to-Digital Converters in Dense Cellular Networks

Stochastic geometry has emerged as a powerful tool for modeling cellular networks, especially in dense deployment scenarios where inter-cell interference is significant. Previous studies have extensively analyzed multi-antenna systems with partial channel state information at the transmitter (CSIT) using stochastic geometry models. However, most of these works assume the use of infinite-resolution analog-to-digital converters (ADCs) at the receivers. Recent advances in low-resolution ADCs, such as one-bit ADCs, offer an energy-efficient alternative for millimeter-wave systems, but the interplay between limited feedback and one-bit ADCs remains underexplored in such networks. This paper addresses this gap by analyzing the optimal feedback rate that maximizes net spectral efficiency in dense cellular networks, modeled using stochastic geometry, with both limited feedback and one-bit ADC receivers. We introduce an approximation of the achievable spectral efficiency to derive a differentiable expression of the optimal feedback rate. The results show that while the scaling behavior of the optimal feedback rate with respect to the channel coherence time remains unaffected by the ADC’s resolution, the absolute values are significantly lower for one-bit ADCs compared to infinite-resolution ADCs. Simulation results confirm the accuracy of our theoretical approximations and demonstrate the impact of ADC resolution on feedback rate optimization.

Insights into stripping losses of negative ions in an ITER-like pre-acceleration system

Abstract The ELISE test facility at IPP Garching hosts an RF-driven negative hydrogen ion source and extraction and acceleration system. Its target is to demonstrate the performance foreseen for the ITER neutral beam injection (NBI) system in terms of extracted current density (329A/m2 in hydrogen, 286A/m2 in deuterium), electron-ion-ratio (<1) and pulse length (up to 3600s in deuterium and 1000s in hydrogen). NBI systems are compromised by a process commonly known as stripping losses (i.e. neutralization of negative ions before they achieve full acceleration). According to theoretical estimations, for a source filling pressure of pfill=0.3Pa, 29\% of the extracted H-/D- ions are lost by stripping in the ITER full-scale NBI system. Experimentally, stripping losses are monitored using Beam Emission Spectroscopy (BES). Previous experimental measurements of the stripping losses at ELISE yielded values around 1.7\%, which were much lower than the 10\% predicted for the pre-accelerator system. The notable difference has sparked concern about the conventional interpretation of the BES experimental measurements used at IPP. The Bavarian Beam Code for Negative Ions (BBCNI) is a full 3D particle tracking code that can also produce synthetic BES spectra. BBCNI is used to evaluate how accurately different analysis techniques determine the stripping losses from the BES. This is achieved by comparing the results with the total simulated count of stripping losses. The analysis method that produces the most accurate results is identified and then systematically applied to evaluate ELISE's data from various experimental campaigns. For a nominal source filling pressure pfill=0.3Pa an average of 5.8\% is measured experimentally when evaluating the data with this method. Although higher than previously determined with BES, stripping losses are still smaller than predicted values. This may open the option to increase the filling pressure in the source as a means to facilitate achieving the targeted ITER conditions.

Oxygen-Doped 2D In2Se3 Nanosheets with Extended In-Plane Lattice Strain for Highly Efficient Piezoelectric Energy Harvesting.

With the emergence of electromechanical devices, considerable efforts have been devoted to improving the piezoelectricity of 2D materials. Herein, an anion-doping approach is proposed as an effective way to enhance the piezoelectricity of α-In2Se3 nanosheets, which has a rare asymmetric structure in both the in-plane and out-of-plane directions. As the O2 plasma treatment gradually substitutes selenium with oxygen, it changes the crystal structure, creating a larger lattice distortion and, thus, an extended dipole moment. Prior to the O2 treatment, the lattice extension is deliberately maximized in the lateral direction by imposing in situ tensile strain during the exfoliation process for preparing the nanosheets. Combining doping and strain engineering substantially enhances the piezoelectric coefficient and electromechanical energy conversion. As a result, the optimal harvester with a 0.9% in situ strain and 10 min plasma exposure achieves the highest piezoelectric energy harvesting values of ≈13.5 nA and ≈420 µW cm-2 under bending operation, outperforming all previously reported 2D materials. Theoretical estimation of the structural changes and polarization with gradual oxygen substitution supports the observed dependence of the electromechanical performance.

CONSCIOUSNESS AS A FACTOR FORMING SOCIETY

The article is devoted to consideration of the properties of consciousness and its influence on social processes. The complexity of researching consciousness as such is pointed out, since it is a kind of screen on which only external things, phenomena, processes are displayed. This screen does not reflect itself even in the case of reflection. The importance of consciously setting predetermined goals of human activity and the need for the unity of people in achieving such goals is considered. It is pointed out the complexity and inconsistency in achieving the goals set by people, in particular, the limitations of the functions of consciousness to predict and plan the consequences of human activity. The question arises as to how the predetermined goal is realized, why what exists in consciousness finds a counterpart in external reality. It is assumed that it already exists in external reality, but not as a reality, but as a possibility. The function of consciousness is to find ways to this desired possibility, to turn it into world is a collection of many possibilities, between which there are ways of transitions and each of which can reach the level of reality. It is pointed out the need for strict control by the subject of a predetermined goal (fiction), the complexity and contradiction of this control, its opposite to freedom of thought and expression. The partial justice and at the same time the limitations and contradictions of the materialistic vision of the influence of consciousness on social processes are shown. It is about the primitivization of the manifestation and the mythologizing of theoretical ideas when they dominate the consciousness of many people. The fragmentation of consciousness and its manifestations are considered. Consciousness is considered as the existence of which we can speak only by its influence on the human body, and the question is raised about how the ideal acts on the material, how thought moves the body. Consciousness shapes society through creativity. Fiction is the basis of real actions and historical processes. Including regarding the organization

Philosophical foundations of posthuman communication studies

The article examines the philosophical foundations of posthuman communication studies – a new branch of the science of communications aimed at studying the nature and structure of technobiomaterial interactions, communications of material and digital actors, their characteristic mechanisms and trends of mutual influence of forces and processes (both human and non–human), leading to the exchange of actions, affects, emotions and meanings, circulation of energy forces and intensities, material formation and discursive diversity, and, thereby, to material changes – multiplication of the possible through the implementation of its specific invariants. A number of changes that necessitate the institutionalization of posthuman communication studies are analyzed: a new understanding of the «human subject» (rejection of the idea of Cartesian subjectivity); revision of the understanding of information (information as a «formation» / procedural generation, rather than a fixed set of data); expansion of the specifics of understanding the processes of interaction and communication (from exchange of information between subjects to process formation and circulation of affects between bodies / objects). A number of philosophical, research and applied theoretical ideas that influenced the formation of the conceptual sphere of posthuman communication studies are considered.

Tleco: A Toolkit for Modeling Radiative Signatures from Relativistic Outflows

A wide range of astrophysical sources exhibit extreme and rapidly varying electromagnetic emission indicative of efficient nonthermal particle acceleration. Understanding these sources often involves comparing data with a broad range of theoretical scenarios. To this end, it is beneficial to have tools that enable not only fast and efficient parametric investigation of the predictions of a specific scenario but also the flexibility to explore different theoretical ideas. In this paper, we introduce Tleco, a versatile and lightweight toolkit for developing numerical models of relativistic outflows, including their particle acceleration mechanisms and resultant electromagnetic signature. Built on the Rust programming language and wrapped into a Python library, Tleco offers efficient algorithms for evolving relativistic particle distributions and for solving the resulting emissions in a customizable fashion. Tleco uses a fully implicit discretization algorithm to solve the Fokker–Planck equation with user-defined diffusion, advection, cooling, injection, and escape and offers prescriptions for radiative emission and cooling. These include, but are not limited to, synchrotron, inverse-Compton, and self-synchrotron absorption. Tleco is designed to be user friendly and adaptable to model particle acceleration and the resulting electromagnetic spectrum and temporal variability in a wide variety of astrophysical scenarios, including, but not limited to, gamma-ray bursts, pulsar wind nebulae, and jets from active galactic nuclei. In this work, we outline the core algorithms and proceed to evaluate and demonstrate their effectiveness. The code is open source and available in the GitHub repository: https://github.com/zkdavis/Tleco.

Te L-subshell x-ray emission induced by lower energy H2+ ions

The L-shell x-ray emission of tellurium induced by H2+ ions impact is investigated in an energy range of 150–300 keV. The blue shifts of various L-subshell x rays and the enhancement of the relative intensity ratios of Lι, Lβ to Lα x ray are observed and interpreted by the multiple ionization of outer-shell electrons. The new experimental x-ray production cross sections, which almost correspond to those of protons with half of the original energy, are extracted and compared with various theoretical estimations. The correction effects of the united atom approximation and the multiple ionization atomic parameters are compared, and the influence of atomic parameters from different databases on the simulations is discussed. Overall, the ECUSAR-MI calculations using theoretical atomic parameters present the best agreement with the experiment results.

Novel Dynamic Behaviors in Fractional Chaotic Systems: Numerical Simulations with Caputo Derivatives

Over the last several years, there has been a considerable improvement in the possible methods for solving fractional-order chaotic systems; however, achieving high accuracy remains a challenge. This work proposes a new precise numerical technique for fractional-order chaotic systems. Through simulations, we obtain new types of complex and previously undiscussed dynamic behaviors.These phenomena, not recognized in prior numerical results or theoretical estimations, underscore the unique dynamics present in fractional systems. We also study the effects of the fractional parameters β1, β2, and β3 on the system’s behavior, comparing them to integer-order derivatives. It has been demonstrated via the findings that the suggested technique is consistent with conventional numerical methods for integer-order systems while simultaneously providing an even higher level of precision. It is possible to demonstrate the efficacy and precision of this technique through simulations, which demonstrates that this method is useful for the investigation of complicated chaotic models.

Dietary Risk Assessment of Cadmium Exposure Through Commonly Consumed Foodstuffs in Mexico.

Cadmium (Cd) is a toxic heavy metal widely distributed in foodstuffs. In Mexico, few studies have evaluated Cd content in foods. This study aimed to determine Cd concentrations in foodstuffs that are highly consumed and bought in Mexico City to identify foods exceeding the Maximum Level (ML) and to assess the health risks of theoretical Cd intake from a diet following the Mexican Dietary Guidelines. A total of 143 foodstuffs were analyzed by atomic absorption spectrophotometry. Theoretical Cd intake was estimated in portions per week and compared with the Cd Tolerable Weekly Intake (TWI = 2.5 μg/kg per body weight). A total of 68.5% of the foodstuffs had detectable Cd concentrations. Higher concentrations were found in oyster mushrooms (0.575 mg/kg), romaine lettuce (0.335 mg/kg), and cocoa powder (0.289 mg/kg). Food groups with higher mean concentrations were vegetables (0.084 mg/kg) and snacks, sweets, and desserts (0.049 mg/kg). Ancho chili and romaine lettuce exceed the ML. The theoretical Cd intake estimation was 1.80, 2.05, and 3.82 μg/kg per body weight for adults, adolescents, and school-age children, respectively. This theoretical Cd intake represents a health risk only for school children exceeding the TWI by 53.2%. Our study confirms the presence and risk of Cd in Mexican foodstuffs and highlights the importance of monitoring programs.

Cartographic animations, a supporting technology for education

Abstract. To date, basic theoretical and methodological ideas of animated cartography have been formed, as well as general schemes for animated maps compilation. However, the technological issue remains relevant in this domain due to the abundance of modern tools that can be used for compilation of animated maps. Particularly, most of currently implemented cartographic animation methodologies require the use of a variety of specialized software, including geographic information systems (GISs), vector and raster graphical editors, video effects editing software, and others. So the data processing and conversion techniques are extremely complicated in some cased, when data converted from one software platform to another.In our study, we established investigation of popular desktop GISs functionality application as a full-cycle animated cartography environment. In such a context, we discover approaches to improve methodology of animated maps automated compilation. To prototype a full-cycle animation in GIS environment, we developed a set of animation algorithms implemented in QGIS and documented the algorithms using UML (Unified Modeling Language) diagrams.

Crown Ether-Magnesium Ion Complexes: A Reliable Theoretical Estimation of Host-Guest Interaction and Binding Energies in a Solvent.

Metal ion detection is of a paramount importance for health monitoring. The host should properly accommodate the desired ion and be selective with respect to other potential guests, which makes devising ion sensors a demanding task. Recently (Phys. Chem. Chem. Phys. 2023, 25, 32656), we suggested a procedure for a computational design of crown ethers that can capture magnesium ions. In the present contribution we apply the same approach to search for Mg2+ trap with thiophene units, in accord with proposed hosts for Na+ and K+ ions (Adv. Funct. Mater., 2016, 26, 514). Additionally, we present a procedure based on the combination of Density Functional Theory based Molecular Dynamics and the Interacting Quantum Fragments methodology for determination of host-guest interaction and binding energies in a model with a large number of explicit solvent molecules. The presented strategy could be applied for identification of the right host for an arbitrary guest.

A dynamic linearized wall model for turbulent flow simulation: Towards grid convergence in wall-modeled simulations

This paper addresses the common issue of (no-)grid convergence in wall-modeled numerical simulations and proposes a dynamic linearization technique applied to the Spalart-Allmaras wall model to achieve a proper behavior on fine grids and low-friction areas. A theoretical analysis of the numerical error committed on the shear stress balance close to the walls is performed. It shows that the error is due to the inappropriate imposition of too steep wall-normal velocity gradients that cannot be properly accounted for on the typical grids used for wall-modeled simulations. Based on this error quantification, a dedicated wall model linearization technique is proposed, following the approach developed by Tamaki, Harada and Imamura in 2017. In the proposed modified linearization method, the linearization distance is modified and adjusted dynamically. This is done according to the theoretical shear stress error estimate, in order to keep the numerical error below a user-defined threshold. The method is applied to well-referenced test cases of increasing complexity from the Turbulence Modeling Resource. Overall, the proposed wall model clearly exhibits appropriate grid convergence properties and is also able to predict accurately non-equilibrium boundary layers and flow separation using proper grid refinement.