General Form Research Articles

Thermo-mechanical modeling of pancakelike domes on Venus

In this paper, we present a mathematical model aimed at describing both the effusive and relaxing phase of pancakelike lava domes on the Venus surface. Our model moves from the recent paper by Quick et al. [“New approaches to inferences for steep-sided domes on Venus,” J. Volcanol. Geotherm. Res. 319, 93–105 (2016)] but generalizes it under several respects. Indeed, we consider a temperature field, playing a fundamental role in the flow evolution, whose dynamics is governed by the heat equation. In particular, we suggest that the main mechanism that drives cooling is radiation at the dome surface. We obtain a generalized form of the equation describing the dome shape, where the dependence of viscosity on temperature is taken into account. Still following Quick et al. [“New approaches to inferences for steep-sided domes on Venus,” J. Volcanol. Geothermal Res. 319, 93–105 (2016)], we distinguish an isothermal relaxing phase preceded by a non-isothermal (cooling) effusive phase, but the fluid mechanical model, developed in an axisymmetric thin-layer approximation, takes into account both shear thinning and thermal effects. In both cases (relaxing and effusive phase), we show the existence of self-similar solutions. In particular, this allows to obtain a likely scenario of the volumetric flow rate which originated this kind of domes. Indeed, the model predicts a time varying discharge, which is maximum at the beginning of the formation process and decreases until vanishing when the effusive phase is over. The model, in addition to fitting well the dome shape, suggests a possible forming scenario, which may help the largely debated questions about the emplacement and lava composition of these domes.

Theory of elastic wave propagation in a fluid-saturated multi-porous medium with multi-permeability

This paper establishes the concept of elastic wave propagation in a multi-porous medium with different permeabilities by assuming there are n distinct pore fluid phases. The dynamic equation of motion of elastic wave propagation through this multi-porous medium is derived based on Lagrangian mechanics. In this regard, the generalized form of mass coefficients and then the energy loss due to the fluid phases in terms of dissipation coefficients are presented for low-frequency limits with the help of Darcy’s Law of multi-phases system. The elastic coefficients of the constitutive equation in terms of compliance matrix are identified using a series of Gedanken experiments. Some significant results regarding the compressional and rotational waves in a multi-porosity medium are derived. The validation of the theory has been shown by comparing it with the existing theory of single and double porosity. It is observed that there are ( n + 1 ) compressional waves corresponding to solid and fluid phases, whereas only one rotational wave is associated with the solid phase. The concept of multi-porosity theory can contribute to a deeper understanding of wave behaviour in a porous medium.

Penalizing the Hard Example But Not Too Much: A Strong Baseline for Fine-Grained Visual Classification.

Though significant progress has been achieved on fine-grained visual classification (FGVC), severe overfitting still hinders model generalization. A recent study shows that hard samples in the training set can be easily fit, but most existing FGVC methods fail to classify some hard examples in the test set. The reason is that the model overfits those hard examples in the training set, but does not learn to generalize to unseen examples in the test set. In this article, we propose a moderate hard example modulation (MHEM) strategy to properly modulate the hard examples. MHEM encourages the model to not overfit hard examples and offers better generalization and discrimination. First, we introduce three conditions and formulate a general form of a modulated loss function. Second, we instantiate the loss function and provide a strong baseline for FGVC, where the performance of a naive backbone can be boosted and be comparable with recent methods. Moreover, we demonstrate that our baseline can be readily incorporated into the existing methods and empower these methods to be more discriminative. Equipped with our strong baseline, we achieve consistent improvements on three typical FGVC datasets, i.e., CUB-200-2011, Stanford Cars, and FGVC-Aircraft. We hope the idea of moderate hard example modulation will inspire future research work toward more effective fine-grained visual recognition.

Quantum–classical correspondence in spin–boson equilibrium states at arbitrary coupling

The equilibrium properties of nanoscale systems can deviate significantly from standard thermodynamics due to their coupling to an environment. We investigate this here for the θ-angled spin–boson model, where we first derive a compact and general form of the classical equilibrium state including environmental corrections to all orders. Secondly, for the quantum spin–boson model we prove, by carefully taking a large spin limit, that Bohr’s quantum–classical correspondence persists at all coupling strengths. This shows, for the first time, the validity of the quantum–classical correspondence for an open system and gives insight into the regimes where the quantum system is well-approximated by a classical one. Finally, we provide the first classification of the coupling parameter regimes for the spin–boson model, from weak to ultrastrong, both for the quantum case and the classical setting. Our results shed light on the interplay of quantum and mean force corrections in equilibrium states of the spin–boson model, and will help draw the quantum to classical boundary in a range of fields, such as magnetism and exciton dynamics.

Research on the Equivalent Criterion for Ratios of Safety Margin in Terms of the Factor of Safety and the Reliability Index Under Lognormal Distribution

The ratio of safety margin is the bridge between deterministic design and reliability design. However, the equivalence criterion between the ratios of safety margin in terms of the factor of safety (FOS) and the reliability index is ambiguous. This paper considers the traditional and reliability-based design method at the same safety level. A general form of the FOS following lognormal distribution is adopted. It was found that the variability of FOS is affected by the normalized gradient and the coefficient of variation of random variable. The ratios of safety margin in terms of the FOS and the reliability index are equivalent in the specific project if the normalized gradient does not vary with the design parameters. The feasibility of applying the ratio of safety margin may be increased in engineering practice.

Investigation of nonlocal granular fluidity models using nuclear magnetic resonance

Nonlocal rheology models describe features in granular flows, such as scale dependence and flow below the yield point, that are not captured by local rheology models. It has been proposed that these features may be described by the transport of a property known as the granular fluidity. In this article, we studied an annular Couette shear cell of lobelia seeds using nuclear magnetic resonance to collect detailed measurements of the velocity distribution and volume fraction. These data were used to study nonlocal granular rheology models. We found that the nonlocal granular fluidity model was capable of accurately describing the decay in the velocity profile along the shear gradient direction. We also measured the dimensionless fluidity and validated the general form of the relation between this quantity and the volume fraction.

Comparison of clinical efficacy and safety of original and generic forms of etoricoxib in patients with knee osteoarthritis

Background. Nonsteroidal anti-inflammatory drugs (NSAIDs) are an important drug class for the treatment of osteoarthritis (OA). Despite existing studies on the bioequivalence of original and generic NSAIDs, comparative studies related to their clinical efficacy and safety are limited. The purpose of the study was to compare the clinical efficacy and safety of the original and generic forms of etoricoxib in patients with knee OA. ­Materials and ­methods. In an open, comparative, randomized, multicenter study, 150 patients with knee OA were examined: group I — 50 persons who received the original etoricoxib (60 mg/d for 10 days), groups II and III — 50 subjects each who received generic etoricoxib (60 mg/d for 10 days). The effectiveness of the treatment was evaluated using the four-component visual analog scale (VAS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Lequesne index before the start of therapy and on the 10th day. Assessment of tolerability and safety was studied by controlling adverse events based on clinical and laboratory indicators. Results. The use of the original and generic forms of etoricoxib in patients with knee OA led to positive dynamics of pain syndrome and functional activity, while the dynamics of indices were the greatest in the case of using the ori­ginal etoricoxib (VAS: group I — 50.0 [35.4–60.0] %, group II — 29.1 [16.7–55.0] % and III — 28.6 [14.3–33.3] %). The most pronounced positive dynamics of the pain syndrome against the background of taking the original etoricoxib compared to the generic forms was registered in the subgroup of patients with severe knee pain (VAS > 60 mm). The use of all forms of etorico­xib was safe and did not lead to serious clinical side effects or clinically signi­ficant changes in laboratory blood parameters. The hi­ghest rates of satisfaction with the treatment by patients and physicians were observed in the case of the original etoricoxib use. Conclusions. The use of the original etoricoxib in patients with knee OA, especially in the presence of severe pain syndrome (VAS > 60 mm) is the most justified and safe.

Determining the parameters of the functioning for a nonlinear ballistic system in a real external environment

Determining the parameters of the functioning for a nonlinear ballistic system in a real external environment

Autonomous assembly of multiple spacecraft by tether-aided rendezvous and docking: From theory to experiment

Utilizing the tether-aided rendezvous and docking to realize an on-orbit autonomous assembly of multiple spacecraft is a novel and prospective space mission. The paper presents the dynamics and control of this assembly mission mode in a spinning scenario numerically and experimentally. The system equations in general form are first established. Based on several feasible assumptions, the coupling effects among the chaser spacecraft are eliminated, a set of simplified governing equations described by the tether length and the libration angle are then obtained. By employing the trapezoidal tether retrieval law, an assembly strategy composed of the tangential and normal thrust controllers is proposed. The operation constraints of the tether tension and the libration angle are explicitly considered. Numerical simulation results verify the feasibility and effectiveness of the designed control strategy. In addition, the corresponding tether-aided assembly process is further validated by the air-bearing experiment based on the upgraded system SOOHLS.

Investigation of the Relationship Between Mothers' Perceptions of Risky Play and Their Children's Self-Concepts

This study was conducted to determine the relationship between the perceptions of mothers of children attending preschool institutions about risky play and children's self-concept and the relationship between gender. In line with this purpose, it was conducted using the relational survey model, one of the quantitative research methods. The sample of the study was determined using the convenience sampling method. The sample of the study consisted of 257 volunteer children and the mothers of the same children. In the study, a general information form developed by the researcher was used to obtain information about the demographic characteristics of the children and their families. As a data collection tool, "Scale for the Attitudes Towards Risky Play at Early Childhood - Parent Form (SATRPEC-PF)" was used to evaluate mothers' perceptions about risky play, and Perception of Child Self-Concept (PCSC) was used to evaluate children's self-concept. The data obtained from the study were created using Spearman Rank Correlation analysis. When the scores obtained from SATRPEC-PF and PCSC were compared, a positive correlation was found between PCSC scores and Pro-beliefs scores from SATRPEC-PF sub-factors, and a negative correlation was found between Feeling Anxiety. No significant relationship was found between Distinguishing Risky Behaviors, Supporting Children, and Parental Support factors. While there was a significant relationship between girls' PCSC scores and SATRPEC-PF Pro-beliefs sub-factor, Distinguishing Risky Behaviors sub-factor, and Feeling Anxiety sub-factor, no significant relationship was found between the Supporting Children and Parental Support sub-factors. A significant relationship was found only between boys' PCSC scores and the Pro-beliefs sub-factor of SATRPEC-PF. Suggestions were presented in line with the findings obtained from the study.

Ensuring informed consent in low-income settings: Opinion piece

In low-income healthcare settings, the implementation of informed consent faces significant challenges despite its pivotal role in upholding patient autonomy and dignity. A study conducted in southeastern Nigeria at the University of Nigeria Teaching Hospital sheds light on these challenges, particularly concerning patient satisfaction and recall of critical information post-consent. While many patients recalled details about their medical condition and planned procedures, there was notably lower recall of associated risks, emphasizing the complexity of conveying risk-related information effectively. Importantly, the study reveals a correlation between patient satisfaction with the consent process and their subsequent recall of information, underlining the intrinsic link between patient engagement, satisfaction, and comprehension. To bridge this gap, tailored communication methods and addressing patient concerns are essential. Systemic deficiencies in the consent process, including generic forms and linguistic barriers, call for interventions such as culturally sensitive consent materials and capacity building for healthcare providers. Looking forward, innovative approaches, including pictorial aids and mobile health applications, should be explored, alongside longitudinal studies to assess their impact. Ultimately, prioritizing patient satisfaction and comprehension in the consent process is crucial for upholding ethical standards in healthcare delivery, even amidst resource constraints.

Dominance of polarization modes and absorption on self-focusing of laser beams in collisionless magnetized plasma

This work investigates the polarization modes i.e., Extraordinary (E-mode) and Ordinary (O-mode) on self-focusing of higher-order mode of elegant Hermite-cosh-Gaussian (EHChG) laser beams within collisionless magnetized plasma medium. In this study, the authors have taken transverse electromagnetic ([Formula: see text]) mode with mode indices (0, 4) and explored. The ponderomotive force is primarily responsible for the dielectric constant’s nonlinearity in this context. Also, WKB and paraxial approximations via the parabolic wave equation approach are used to establish the general form of differential equations for beam-width parameters in both transverse dimensions of the beam. In this paper, the authors have theoretically investigated the dominance of polarization modes and absorption coefficient on self-focusing. The final results show good enhancement of laser propagation through collisionless plasma medium.

GRAPHIC SUPPORT FOR THE OPERATION OF AIRCRAFT POWER UNITS

The main task of operators is to maintain the airworthiness of aircraft by implementing the technologies outlined in the sets of documents attached to standard products.Engines, the main source of energy for flight, usually work in conjunction with many systems, each of which, in turn, is accompanied by instructions and manuals to ensure operability. In accordance with accepted practice, most of the disaggregated information is provided in text form. These forces you to remember the necessary data or constantly search for it in dozens of updated and replaced pages of the provided technologies, or create your own convenient techniques that allow you to conduct parametric analyzes and develop decisions on control actions to correct the technical condition. Using examples of power plants with turboprop engines, approaches to the development and application of step-by-step unified graphical generalizations of processes and control parameter values, combined with indications of characteristics setting elements, are proposed. For the full cycle of work, the article proposes the most convenient, applicable to different types of power plants, unified method for constructing compact representations of all information in a generalized form. Recommendations have been developed for monitoring, adjusting characteristics and making decisions on the prospects for further operation.The methods have been tested under operating conditions, having confirmed their convenience and effectiveness at different stages of operation, and can be recommended for inclusion in Flight Operations Manuals created by airlines in relation to the range of operating conditions of their aircraft fleet.

Quaternion form of the electromagnetic reciprocity theorem

In this paper, the general forms of quaternion electromagnetic field mutual energy-momentum equations (QEMF-MEME) and quaternion electromagnetic field energy-momentum reciprocal equations (QEMF-EMRE) in frequency domain are derived based on the quaternion-electromagnetic-field equations. It has been discovered that QEMF- EMRE is a reflection of the electromagnetic interaction between lagging and leading waves. The real and imaginary parts of scalar, the real and imaginary parts of vector of QEMF-EMRE correspond to the Feld-Tai reciprocity theorem, Lorentz reciprocity theorem, and the two sets of momentum reciprocity theorems, respectively. While, QEMF-MEME reflects the electromagnetic interaction of two sets of lagging waves, and its real scalar, imaginary scalar, real-vector, and imaginary-vector parts are the Feld-Tai reciprocal energy theorem, the reciprocal energy theorem, the two sets of reciprocal momentum theorem.

Impact of Diimine Ligand on Singlet-to-Triplet Charge Transfer Electroabsorption in Iron and Ruthenium Complexes.

The electroabsorption and absorption spectra of eight homoleptic complexes of the general form [M(LL)3]2+ where M = Ru, Fe, and LL = 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), and 4,4',-(R)2-bpy where R = -OCH3, -CF3, were quantified at 77 K in a butyronitrile glass. Intense metal-to-ligand charge transfer (MLCT) absorption bands were evident in the visible region. Electroabsorption spectra measured with applied electric fields >0.2 MV/cm were analyzed by the two-state Liptay model. Significant light-induced dipole moment changes of = 4-13 D were found consistent with a metal-to-ligand charge transfer (MLCT) excited state comprised an electron localized on a single diimine ligand, [MIII(LL-)(LL)2]*2+, in the initially formed Franck-Condon excited state. A low energy feature evident in the electroabsorption spectra was assigned to a direct singlet-to-triplet MLCT excited state. The identity of the diimine ligand had an unexpected and large impact on these transitions. Analysis relative to the higher energy absorption provides a comparison of spin-allowed and disallowed transitions for first- and second-row transition metal complexes. With the notable exception of [Fe(CF3bpy)3]2+, the change in dipole moment for the 3MLCT excited states was less than or equal to that of the 1MLCT excited states. The charge transfer distances for the iron complexes were generally larger than those for the Ru complexes, a behavior attributed to a smaller degree of iron-diimine coupling in the ground state. A striking result was the sensitivity of the extinction coefficient and spectral profile of the low energy electroabsorption assigned to the identity of the diimine ligand; data that suggests electronic coupling with ligand localized triplet states and high spin metal centered states must be considered when modeling the Franck-Condon excited state.

A new analytic approach and its application to new generalized Korteweg‐de Vries and modified Korteweg‐de Vries equations

The current study is important from two perspectives. Firstly, in this article, we suggest a novel analytical technique for creating the exact solutions to nonlinear partial differential equations (NLPDEs). In order to study the dynamical behaviors of various wave phenomena, we can construct the several exact solutions in the form of Jacobi elliptic solutions, hyperbolic solutions, trigonometric solutions, and exponential solutions by using this method. Secondly, we consider a more generalized form of the (2+1)‐dimensional Korteweg–de Vries (KdV) and modified Korteweg‐de Vries (mKdV) equations that plays an important role in describing the shallow water. We successfully extract several soliton solutions for the examined equation. By choosing the appropriate parameters, some graphs of the discovered solutions have been represented in the figures. Every obtained solution has been demonstrated to satisfy the corresponding equation. The findings demonstrate that the method can be applied to solve a number of nonlinear evolution equations. The new solutions and the paper's findings could improve our understanding of how the waves move through shallow water and open up new research avenues.

Intrinsic Harnack’s Inequality for a General Nonlinear Parabolic Equation in Non-divergence Form

AbstractWe prove the intrinsic Harnack’s inequality for a general form of a parabolic equation that generalizes both the standard parabolic p-Laplace equation and the normalized version arising from stochastic game theory. We prove each result for the optimal range of exponents and ensure that we get stable constants.

Mitigation of numerical issues appearing in transient analyses when applying fractional derivative approximations

Due to the potential decrease of the computation time for problems with fractional order derivatives, and due to the extension of the range of applicable solvers for a given problem, the approximation of fractional derivatives (e.g., using Oustaloup’s method) is an important and frequently discussed topic. A significant problem that can occur (although one that is not discussed very often) when approximations are applied concerns the potential numerical issues that can arise when applying these approximations in a transient analysis, e.g., as shown in the paper, in a time-stepping solver. This paper examines five different methods for approximating the fractional derivative (Oustaloup’s method, a refined Oustaloup method, a modified continued fraction expansion method, Matsuda’s method and Charef’s method). An important preliminary step in the analysis was the establishment of the general form of FDAE (fractional differential-algebraic equations), the general form of the applied approximations and the general form of the DAE (differential-algebraic equations) resulting from the approximation. This allowed for a precise description of the equations according to which the transformation from the FDAE to the approximating DAE takes place. Three problems derived from studies in electrical engineering have been introduced into the analysis (a linear circuit problem, a circuit problem with nonlinear fractional elements, and a problem featuring nonlinearities and pregenerated noise). For these problems, the conditions in which numerical issues appear have been studied in detail. They are the main motivation of this study as these issues are so significant that they often result in zero-solutions or solutions tending to infinity (giving an impression as if the system is unstable). Modifications and alternatives of the transformation into the DAE, that aim at the mitigation of these numerical errors, are mentioned later. The final result is very satisfactory, where the algorithm for the transformation of the FDAE to the approximating DAE practically eliminates the most important barriers (which was the impossibility of using approximations above a certain order due to the mentioned numerical issues). The study presented in this paper is motivated by problems in electrical engineering but due to its generality it is also applicable in other fields where fractional calculus is used.

Gene-specific somatic epigenetic mosaicism of FDFT1 underlies a non-hereditary localized form of porokeratosis

Porokeratosis is a clonal keratinization disorder characterized by solitary, linearly arranged, or generally distributed multiple skin lesions. Previous studies showed that genetic alterations in MVK, PMVK, MVD, or FDPS-genes in the mevalonate pathway-cause hereditary porokeratosis, with skin lesions harboring germline and lesion-specific somatic variants on opposite alleles. Here, we identified non-hereditary porokeratosis associated with epigenetic silencing of FDFT1, another gene in the mevalonate pathway. Skin lesions of the generalized form had germline and lesion-specific somatic variants on opposite alleles in FDFT1, representing FDFT1-associated hereditary porokeratosis identified in this study. Conversely, lesions of the solitary or linearly arranged localized form had somatic bi-allelic promoter hypermethylation or mono-allelic promoter hypermethylation with somatic genetic alterations on opposite alleles in FDFT1, indicating non-hereditary porokeratosis. FDFT1 localization was uniformly diminished within the lesions, and lesion-derived keratinocytes showed cholesterol dependence for cell growth and altered expression of genes related to cell-cycle and epidermal development, confirming that lesions form by clonal expansion of FDFT1-deficient keratinocytes. In some individuals with the localized form, gene-specific promoter hypermethylation of FDFT1 was detected in morphologically normal epidermis adjacent to methylation-related lesions but not distal to these lesions, suggesting that asymptomatic somatic epigenetic mosaicism of FDFT1 predisposes certain skin areas to the disease. Finally, consistent with its genetic etiology, topical statin treatment ameliorated lesions in FDFT1-deficient porokeratosis. In conclusion, we identified bi-allelic genetic and/or epigenetic alterations of FDFT1 as a cause of porokeratosis and shed light on the pathogenesis of skin mosaicism involving clonal expansion of epigenetically altered cells.

Theoretical and practical investigation of ion-ion association in electrolyte solutions.

In this study, we present a new equation of state for electrolyte solutions, integrating the statistical associating fluid theory for variable range interactions utilizing the generic Mie form and binding Debye-Hückel theories. This equation of state underscores the pivotal role of ion-ion association in determining the properties of electrolyte solutions. We propose a unified framework that simultaneously examines the thermodynamic properties of electrolyte solutions and their electrical conductivity, given the profound impact of ion pairing on this transport property. Using this equation of state, we predict the liquid density, mean ionic activity coefficient, and osmotic coefficient for binary NaCl, Na2SO4, and MgSO4 aqueous solutions at 298.15K. Additionally, we evaluate the molar conductivity of these systems by considering the fraction of free ions derived from our equation of state in conjunction with two advanced electrical conductivity models. Our results reveal that, while ion-ion association has a minimal influence on the modification of the predicted properties of sodium chloride solutions, their impact on sodium and magnesium sulfate solutions is considerably more noticeable.