Correct Solution Research Articles

On the consistency of three-dimensional magnetohydrodynamical lattice Boltzmann models

The lattice Boltzmann method (LBM) for magnetohydrodynamics (MHD) was first developed for two-dimensional (2D) flows. The magnetic component of the Lorentz force is obtained from the divergence of the Maxwell stress tensor, which is recovered by an appropriate modification to the LBM equilibrium distribution function for the solution of the velocity field. Although this method has subsequently been applied to three-dimensional (3D) flows, we show that several common modifications of the 3D equilibrium distribution function cannot simultaneously recover the Maxwell stress tensor and conserve mass exactly. Our study brings attention to this theoretical issue since such inconsistent models have been used in recent 3D LBM MHD simulations. Both requirements can be simultaneously satisfied by incorporating an additional model term to the 3D equilibrium distribution function. Three variants of Hunt's flow in a rectangular channel are considered to illustrate the undesirable consequences of using inconsistent models: 1) flow driven by a pressure difference, 2) flow driven by an external body force, and 3) inclusion of a streamwise gradient in magnetic pressure. While spurious errors were observed using inconsistent models due to the violation of mass conservation or inaccuracy in the Maxwell stress tensor, the consistent model always achieves the correct solutions in these cases and is recommended for 3D MHD simulations.

The Recovery of the Natural Desire for Salvation:

Dynamic Theodicy (DT) is a broad concept we bring up to designate some modern Philosophical Theology attempts to reconcile the necessary and perfect existence of God with the contingent characteristics of human life. In this paper we analyze such approaches and discuss how they have become incomprehensible because the metaphysical assumptions implicit in these explanations have lost their intrinsic relation to the natural human desire for salvation. In the first part we show Charles Hartshorne's DT-model, arising from the modal logic of perfection, and the modern rational problems of this position in making infinite-necessary Being (God) and finite-contingent being (human) compatible. We note that at the heart of the contradictions in this DT account is a dialectical mode of thinking that makes it difficult to find a correct solution to this dichotomy, and to assume a human desire that could be considered related to lifelong goals. In the second part, supported by the proposal of Hans Urs von Balthasar's DT, we develop the concepts of bodily vulnerability, corporeal intentionality, and natural desire for salvation, which come from an Aristotelian-Thomistic thought. This theory is established in order to build an argument, following Alasdair MacIntyre’s ethical framework, on how to make possible the recovery of a metaphysical and anthropological desire that transcends natural aging and goes beyond death. We conclude that both human dependence and the virtues that arise naturally when human beings decide to seek the good of their transcendent condition, make it possible to recover the natural desire for salvation through divine and human love.

Surface reconstruction and thickness error calculation of optical components with a complex curved surface

The increasing demand for free-form irregular optical components in both military and civilian sectors has made the inspection of such unique shapes a central challenge that hinders their production and use. In particular, the shape and thickness errors of low- and medium-precision components thermally pressed from flat optical materials are greater than those of hard brittle optical components fabricated by subtractive manufacturing, and the resulting impact on human vision is more severe. Reasonable, convenient, efficient, and accurate 3D scanning and data processing for surface reconstruction that combines application scenarios and batch manufacturing needs are urgently needed. Based on the principles of optical ray tracing and triangulation processing, the sampling and calculation of optical path thickness proposed in this paper effectively establish a theoretical model for macroscopic distortion, providing a reasonable solution for distortion correction, batch manufacturing of free-form surface pressing formed components, and defect repair.

Comment on “Modulational instability and soliton trains in optical fiber media with real and imaginary Raman gains”

In their recent article, Nfor et al. [Optik - International Journal for Light and Electron Optics 285 (2023) 170951, https://doi.org/10.1016/j.ijleo.2023.170951] have studied, through a dissipative nonlinear Schrödinger equation, the modulational instability and soliton trains in optical fiber media with real and imaginary Raman gains. After finding a steady-state solution of this equation, they have applied the linear stability analysis to investigate its modulational instability. It appears that (i) their proposed steady-state solution is not really a continuous wave solution of their model equation, and (ii) their ansatz used for the modulation perturbation function violate all mathematical/physical rules, leading thus to an inappropriate results. Moreover, during their development on exact analytical solutions, authors have not established conditions under which those analytical solutions may exist, as one can easily verify in subsection 3.1. It is the aim of the present comment to correct all shortcomings about the modulational instability study carried out in their study. We start by presenting the correct steady-state solution of the considered dissipative nonlinear Schrödinger equation, and then investigate with details its modulational instability. We end this comment by establishing conditions under which equation (15) admits analytical solutions of form (16) when a6=0, and the present some other interesting solutions of this equation (16).

230 Machine Learning for Automated and Real-time 2D-3D Registration of the Spine Using Only a Single Radiograph

INTRODUCTION: Authors present a 2-dimensional to 3-dimensional (2D-3D) registration algorithm that identifies the position of a C-arm relative to a 3D volume. METHODS: This work utilizes digitally reconstructed radiographs (DRR) which are synthetic radiographic images generated by simulating the x-ray projections as they would pass through a CT volume. To evaluate our algorithm, we used cone-beam CT data from 127 patients obtained from a de-identified registry of cervical, thoracic, and lumbar scans. We systematically evaluated and tuned a self-supervised algorithm, quantified the limitations and convergence rate of our model by simulating C-arm registrations with 80 randomly simulated DRRs for each CT volume. The endpoints for this study were the time to convergence, accuracy of convergence for each of the C-arm's degrees of freedom (DoF), and overall registration accuracy based on a voxel-by-voxel measurement. RESULTS: 10,160 unique fluoroscopic images were simulated from 127 CT scans. Our algorithm successfully converged to the correct solution 81% of the time with an average of 1.97 seconds of computation. The fluoroscopic images for which the algorithm converged to the solution achieved 99.9% registration accuracy despite only utilizing single-precision computation for speed. Our algorithm was found to be optimized for convergence when the search space was limited to a ± 45° offset in the RAO/LAO, cranial/caudal and receiver rotation angles with the radiographic isocenter contained within 8000cm3 of the volumetric center of the CT volume. CONCLUSIONS: The machine learning algorithm we present has the potential to aid surgeons with many aspects of spine surgery through an automated 2D-3D registration process. Future work will focus on algorithmic optimizations adn deep-learning to improve the convergence rate and speed profile.

Analysis of Field Dependent and Field Independent Cognitive Styles in Solving Science Problems in Elementary Schools

This research aims to determine the results of the Science Problem Solving Test, describing students' Field Dependent and Field Independent cognitive styles in solving science problems. The research method used is Mixed Methods, which uses Sequential Explanatory Design. The research results showed that the field-independent and field-dependent students' science problem-solving tests were good. This is proven by using a one-sample t-test with a Sig (2-tailed) result of 0.005. which is smaller than 0.05. The cognitive style of field-dependent students in solving science problems, according to the Polya Stage theory, have difficulty absorbing information, so they do not understand the problem and are unable to explain using their sentences, think globally. The cognitive style of field-independent students in solving science problems is effortless to absorb information so that they can understand the situation thoroughly, analytically, and systematically so that they can present the correct solution steps by determining arithmetic operations that are relevant to the problem.

MODELING OF TWO-FREQUENCY SIGNAL SCATTERING ON A DIFFRACTION STRUCTURE

To date, one of the important and urgent tasks of the science of electrodynamics is to study the scattering characteristics of various complex electrodynamic objects. Among them, hollow structures can be distinguished, which are part of antenna systems and structures of various technical facilities. Their contribution to the levels of electromagnetic fields in the anterior hemisphere can be quite large. The correct solution to the problem of scattering of electromagnetic wave scattering characteristics is associated with the use of appropriate methods. The paper considers the solution of the problem based on the method of integral equations. During the analysis of the two-frequency effect, the use of the wavelet transform is considered.

Institute of Post-Service Provision of Judges in the Russian Federation

Introduction. The issues of post-service (pension) provision of judges in Russia are both the subject of scientific discussion and numerous court disputes. We believe that the correct solution of both applied and private scientific problems is impossible without a theoretical understanding of the essence of the institution of monthly lifelong maintenance and its place in the pension system of the Russian Federation. Methods. The analysis of the essence of judges’ pension provision is based on the comparative legal method: monthly lifetime maintenance is compared with pension provision. The historical method is used: the evolution of the pension system of judges in Russia is considered. Results. The features of the institution of monthly lifelong maintenance of judges, its differences from other types of pension provision in terms of the functions performed, the procedure, conditions of appointment, the possibility of depriving a person of these payments are revealed. Monthly lifetime maintenance cannot be combined with pension provision. Unlike a pension, the condition for obtaining an monthly lifetime maintenance is not only the onset of a certain period (age, length of service), but also the conscientious performance of one’s official duties, as well as compliance with prohibitions during the entire period of employment as a judge. The condition for obtaining an monthly lifetime maintenance is not only the judge’s past work activity, but also his work activity and even lifestyle after retirement. The level of pension provision for judges significantly exceeds the level of pension provision for ordinary citizens in terms of the coefficient of replacement of earnings. Discussion and Conclusion. At its core, the monthly lifetime maintenance of a judge is a kind of pension provision. However, this institution has such unique parameters that it is quite justifiably designated by the legislator as a separate legal term.

Treatment of Late Infective Prosthetic Endocarditis Complicated by Cerebral Infarction with Vegetations: Pharmacotherapeutic Approach (Case Report)

Prosthetic endocarditis is a serious complication in a long term. Vegetation as a thromboembolic complication leads to neurologic deficit varying in severity.
 Case description. A 35-year-old female patient F. underwent surgical treatment at the Department of Surgical Treatment of Acquired Heart Diseases of the National Amosov Institute of Cardiovascular Surgery on September 07, 2016: aortic valve replacement with wrapping tape operation II. The patient was discharged from the hospital on the 9th day after surgery in a satisfactory condition. On November 20, 2019, the patient was admitted to the Institute with the diagnosis of late infective prosthetic aortic valve endocarditis, status post aortic valve replacement and wrapping tape operation in 2016, first-degree atrioventricular block, cerebral infarctions in multiple locations with hemorrhagic transformation, with aphasia elements, ataxia, right-sided pyramidal insufficiency and suspected meningitis. After 21 days of drug therapy, the patient responded to treatment successfully and was discharged from the hospital in a satisfactory condition without surgical treatment.
 Conclusions. Taking into consideration the serious condition of the patient, timely and carefully selected drug therapy can be the correct solution for the treatment of patients with late infective endocarditis. Thus, surgery is not always the treatment of choice.

Colorizing Multi-Modal Medical Data: An Autoencoder-based Approach for Enhanced Anatomical Information in X-ray Images

Colourisation is the process of synthesising colours in black and white images without altering the image’s structural content and semantics. The authors explore the concept of colourisation, aiming to colourise the multi-modal medical data through X-rays. Colourized X-ray images have a better potential to portray anatomical information than their conventional monochromatic counterparts. These images contain precious anatomical information that, when colourised, will become very valuable and potentially display more information for clinical diagnosis. This will help improve understanding of these X-rays and significantly contribute to the arena of medical image analysis. The authors have implemented three models, a basic auto-encoder architecture, and two combined learnings of the autoencoder module with transfer learning of pre-trained neural networks. The unique feature of this proposed framework is that it can colourise any medical modality in the medical imaging domain. The framework’s performance is evaluated on a chest x-ray image dataset, and it has produced benchmark results enabling high-quality colourisation. The biggest challenge is the need for a correct solution for the mapping between intensity and colour. This makes human interaction and external information from medical professionals crucial for interpreting the results.

Eliciting Kemeny Rankings

We formulate the problem of eliciting agents' preferences with the goal of finding a Kemeny ranking as a Dueling Bandits problem. Here the bandits' arms correspond to alternatives that need to be ranked and the feedback corresponds to a pairwise comparison between alternatives by a randomly sampled agent. We consider both sampling with and without replacement, i.e., the possibility to ask the same agent about some comparison multiple times or not. We find approximation bounds for Kemeny rankings dependant on confidence intervals over estimated winning probabilities of arms. Based on these we state algorithms to find Probably Approximately Correct (PAC) solutions and elaborate on their sample complexity for sampling with or without replacement. Furthermore, if all agents' preferences are strict rankings over the alternatives, we provide means to prune confidence intervals and thereby guide a more efficient elicitation. We formulate several adaptive sampling methods that use look-aheads to estimate how much confidence intervals (and thus approximation guarantees) might be tightened. All described methods are compared on synthetic data.

Specifying angular reference for robust three-phase state estimation

While the phase angle of any of the bus voltages can be chosen as the angular reference in the state estimation formulation of positive sequence networks, the same approach does not readily extend to three-phase network state estimation problem. It is commonly assumed that there is at least one bus where the bus voltages are perfectly balanced with phase angles displaced ±120° and these balanced three phase voltages are used as the three-phase reference in solving the three-phase state estimation problem. This assumption may be quite realistic in transmission networks, and for distribution networks with a strong transmission system connection. However, it might not be realistic to assume existence of a perfectly balanced reference bus in today’s distribution systems with ever increasing penetration of renewable sources or for isolated operation of microgrids. In this paper, a novel state estimation formulation will be presented which facilitates correct solution irrespective of the existence of buses with perfectly balanced voltages. The new formulation is general, and lends itself to bad data processing. It yields accurate results in any three-phase power system irrespective of its operating conditions (balanced or highly unbalanced), configuration (isolated microgrid, connected to transmission system, etc.) and whether or not it contains any synchronous generators. The performance of the method is validated using the IEEE 123 bus three-phase system.

3D Numerical Cross-Section Analysis of a Tapered Beam Slice

Cross-section analysis is an important tool used to recover stresses and strains in a structure at specific cross-sections of arbitrary geometries, without the need for a full 3D model. This is particularly essential for large-scale structures such as aircrafts, wind turbine blades, etc. where making a full model can be computationally very expensive or impractical. The majority of currently available cross-section analysis frameworks are based on stepwise prismatic assumptions, which are hardly suited for the analysis of tapered beams. In fact, high-fidelity stress analysis obtained from analytical and full 3D models shows that predictions of stepwise prismatic approximations can significantly deviate from the correct solution of tapered beams. In this work, a prismatic 3D cross-section analysis method is extended to analyze a symmetrically tapered finite cross-section slice. In this study, the cross-section slice is discretized with 8-node and 20-node solid elements. The boundary conditions are applied as six constraint equations via the Lagrange multiplier method. The external nodal forces acting on the cross-section faces are obtained from the equivalent tractions induced by the cross-section forces. The developed numerical model is validated against the exact analytical solutions of a wedge as well as commercial finite element (FE) software COMSOL and it is shown that the numerically predicted displacement and stress fields agree well with those provided by the wedge’s analytical solution and the FE COMSOL results. This work contributes to the advancement of high-fidelity numerical tapered cross-section analysis methods with an application for many engineering structures.

Elastic, flat and rounded finite contacts: When should we use half-plane theory?

For a flat contact with radiused edges, it is shown that when the flat portion of the contact is small compared to the radius portion of the contact, half-plane theory may confidently be used, and the amount of coupling present is extremely small. When the flat region is large a good quality solution may be used by a different route, using the solution for a square-ended punch together with a corrective solution formed from a three-quarter plane problem but with a radius at the corner. The degree of coupling is captured well. Intermediate geometries are discussed in the text. A further, important, refinement is the fitting of a third solution, developed using half-plane theory for a slightly rounded, flat semi-infinite contact, as this provides an analytical description of the near-edge tractions, and is rigorously fitted into the edge of the three-quarter plane solution.

Interaction diagrams of thin-walled, open cross section PC beams

Thin-walled, open cross section PC (prestressed concrete) beams are widely used in precast structures. Nevertheless, the analytical computation of their load carrying capacity under bending and torsion is still an unsolved problem. This is because of the markedly non-linear behaviour of both steel and concrete and of the asymmetry of the behaviour of concrete in tension and compression. This involves a search for the correct solution from a physical point of view (among those mathematically admissible) based on trial-and-error methods of numerical analysis.This paper suggests a method to evaluate the interaction diagrams under bending and torsion. According to this method the solving system is made by two equilibrium plus two compatibility equations. Some examples show the outcomes of this approach.

The risk of hazards in laboratories of educational groups in the Faculty of Health, Shahid Sadougi University of Medical Sciences, Yazd-2023

Introduction: Improving the safety of working environments is one of the duties of any efficient system. Evaluating the risk of hazards is one of the most efficient ways for increasing safety important issues. Paying attention to the statistics of laboratory accidents and the positive effects of risk assessment in order to improve safety is of great importance. Materials and Methods: The present study was practical in terms of purpose, and cross-sectional in terms of descriptive-analytical method, which to evaluate the laboratories of Shahid Sadoqhi University of Medical Sciences, Yazd, using a quantitative three-dimensional cost equation. Based on the regular observation of existing processes and equipment, the evaluation team used a quantitative risk equation as an indication of safety performance at the level of laboratories. The ranking was based on the probability of risk, the frequency of effective exposure, and the maximum damage potential through a quantitative equation. Finally, the risk rate score of each laboratory was determined and the ranking of the risk level of the laboratories was announced. Suggested corrective solutions were presented and the evaluation was repeated. After collecting the data, it was entered into SPSS 20 software and interpreted using descriptive and analytical statistics. Results: In general, 52% of the risks identified in laboratories are at a low risk level. The highest and lowest average evaluation scores were 55.86 ± 30.89 for environmental chemistry and 28.38 ± 13.51 for food safety and health research laboratory, respectively. The highest evaluation score was given to the environment laboratory. There was a significant relationship between the risk components before and after providing the suggested solutions. Conclusion: According to the results of the research, the overall safety status of the educational laboratories in the Faculty of Health is at a relatively favorable level. However, chemical hazards and thermal safety are the highest priority to control and perform better regarding improvement.

The Effect of Visual Reasoning on Arithmetic Word Problem Solving

First-grade students often encounter challenges in understanding and solving arithmetic word problems due to their limited reading comprehension abilities. Despite these difficulties, students may employ arbitrary strategies, such as combining numbers based on specific keywords, even if they lack a full understanding of the problems. Research suggests that effective mathematical reasoning involves the use of visual mental representations during the problem-solving process. To address this, some studies have explored methods to enhance students’ comprehension of word problems. Building on this, the current study explores the impact of first-grade pupils creating visual representations of problem situations on their comprehension and the number of correct solutions. In a typical math class, 45 first graders received a paper-and-pencil task, and, in a visual context, they solved similar problems after reading and illustrating the situation. The findings reveal that while most participants correctly represented the problem situations through drawing, about half struggled to determine the numeric solutions. Nevertheless, the visual context led to an increase in the number of correct problem solutions compared to the normal context, suggesting the potential benefits of incorporating visual representations in enhancing comprehension and problem-solving skills.

Deep learning-based partial volume correction in standard and low-dose positron emission tomography-computed tomography imaging.

Positron emission tomography (PET) imaging encounters the obstacle of partial volume effects, arising from its limited intrinsic resolution, giving rise to (I) considerable bias, particularly for structures comparable in size to the point spread function (PSF) of the system; and (II) blurred image edges and blending of textures along the borders. We set out to build a deep learning-based framework for predicting partial volume corrected full-dose (FD + PVC) images from either standard or low-dose (LD) PET images without requiring any anatomical data in order to provide a joint solution for partial volume correction and de-noise LD PET images. We trained a modified encoder-decoder U-Net network with standard of care or LD PET images as the input and FD + PVC images by six different PVC methods as the target. These six PVC approaches include geometric transfer matrix (GTM), multi-target correction (MTC), region-based voxel-wise correction (RBV), iterative Yang (IY), reblurred Van-Cittert (RVC), and Richardson-Lucy (RL). The proposed models were evaluated using standard criteria, such as peak signal-to-noise ratio (PSNR), root mean squared error (RMSE), structural similarity index (SSIM), relative bias, and absolute relative bias. Different levels of error were observed for these partial volume correction methods, which were relatively smaller for GTM with a SSIM of 0.63 for LD and 0.29 for FD, IY with an SSIM of 0.63 for LD and 0.67 for FD, RBV with an SSIM of 0.57 for LD and 0.65 for FD, and RVC with an SSIM of 0.89 for LD and 0.94 for FD PVC approaches. However, large quantitative errors were observed for multi-target MTC with an RMSE of 2.71 for LD and 2.45 for FD and RL with an RMSE of 5 for LD and 3.27 for FD PVC approaches. We found that the proposed framework could effectively perform joint de-noising and partial volume correction for PET images with LD and FD input PET data (LD vs. FD). When no magnetic resonance imaging (MRI) images are available, the developed deep learning models could be used for partial volume correction on LD or standard PET-computed tomography (PET-CT) scans as an image quality enhancement technique.

Research on reconstruction of diffraction tomography based on prior information

Under coherent light illumination, several approaches need either angle scanning or diffuser rotating to reconstruct the image through opaque scattering media. We propose a linear model to restore the hidden object through the actual power spectrum with disturbance of the scattering layer. The experimental results confirm that, the algorithm quickly converge to the only correct reconstruction solution with the accuracy power spectrum pattern of Fourier transform, and the method can reconstruct the high accuracy image of the object hidden by the scattering media with one-shot power spectrum.

SAKKOKI'S POETIC WORKMANSHIP (EXAMPLE OF GHAZALS OF XAMD AND NAT)

As a result of the requirement to follow the principles of classism for almost a century before independence, many issues did not find their true and impartial, historically correct interpretation and solution. In fact, the study of these topics should be considered "a great positive event for our time, for the entire world literature." in this article, we will consider the ghazals of praise and praise given in "Devon of Mavlano Sakkoki" prepared for publication by literary scholars M. Hasanova, H. Sheraliyev.