Theoretical Analysis Research Articles

Calculation of steel corrosion rate of reinforced concrete slab based on rust expansion crack.

This study aims to develop a refined calculation model that incorporates the effects of distributed reinforcement on crack propagation, validated through experimental and theoretical analysis, to improve the accuracy and applicability of nondestructive corrosion assessments. In this paper, two reinforced concrete slabs were made to consider the influence of distributed reinforcement on the corrosion process of main reinforcement.An accelerated surface cracking method was used, employing reinforcement electrification. This approach tested the relationship between crack width in reinforced concrete slabs and the corrosion rate of main reinforcement. On the basis of the existing calculation model of the relationship between the corrosion rate of reinforcement and the width of concrete surface crack, combined with the development mechanism of concrete surface crack caused by the corrosion expansion of main reinforcement under the lateral constraint conditions, a calculation model of the surface crack width of reinforced concrete slab and the corrosion rate of reinforcement is established. The comparison shows that the calculation results of the model in this paper can better reflect the test rules, and provide a reference for nondestructive quantitative detection of reinforcement corrosion in concrete structures.

Slip flow in Tesla disk turbines

Purpose This study aims to provide a theoretical analysis of the influence of radial and tangential slip effects on the flow and pressure fields within a Tesla disc turbine. Design/methodology/approach This study closely follows the recently proposed theory in Sengupta and Guha (2012), which builds upon the verified experimental results of Lemma et al. (2008). This study modifies the parabolic nature of the velocity field by introducing radial and azimuthal slip factors. The mathematical formulation establishes that the effective radial velocity depends solely on radial slip, while the effective tangential velocity and pressure become functions of both radial and azimuthal slip. Findings Closed-form solutions reveal the impact of these slips on the performance of velocity and pressure gradient profiles from the inlet rotor to the central outlet rotor of the turbine. The analysis reveals that slip action reduces the Tesla disc turbine’s flow field, prioritizing the conservation of angular momentum over drag forces. However, as particles move away from the inlet rotor, slips also enhance the pressure gradient. Interestingly, this study identifies a threshold for the combination of slip parameters: below this threshold, drag torque increases, but it sharply decreases above it. Originality/value This study showcases that the rotational speed of the Tesla disc for zero torque initially increases with small slips but decreases for larger ones.

Penalty Strategies in Semiparametric Regression Models

This study includes a comprehensive evaluation of six penalty estimation strategies for partially linear models (PLRMs), focusing on their performance in the presence of multicollinearity and their ability to handle both parametric and nonparametric components. The methods under consideration include Ridge regression, Lasso, Adaptive Lasso (aLasso), smoothly clipped absolute deviation (SCAD), ElasticNet, and minimax concave penalty (MCP). In addition to these established methods, we also incorporate Stein-type shrinkage estimation techniques that are standard and positive shrinkage and assess their effectiveness in this context. To estimate the PLRMs, we consider a kernel smoothing technique grounded in penalized least squares. Our investigation involves a theoretical analysis of the estimators’ asymptotic properties and a detailed simulation study designed to compare their performance under a variety of conditions, including different sample sizes, numbers of predictors, and levels of multicollinearity. The simulation results reveal that aLasso and shrinkage estimators, particularly the positive shrinkage estimator, consistently outperform the other methods in terms of Mean Squared Error (MSE) relative efficiencies (RE), especially when the sample size is small and multicollinearity is high. Furthermore, we present a real data analysis using the Hitters dataset to demonstrate the applicability of these methods in a practical setting. The results of the real data analysis align with the simulation findings, highlighting the superior predictive accuracy of aLasso and the shrinkage estimators in the presence of multicollinearity. The findings of this study offer valuable insights into the strengths and limitations of these penalty and shrinkage strategies, guiding their application in future research and practice involving semiparametric regression.

Impact of the non-ideal condition in the analysis of high voltage gain switched impedance inverter with cost perspectives

Switched impedance inverters are a category of power electronic converters that can be applied across various applications through the implementation of appropriate control methods. This paper proposes a switched impedance inverter characterized by a high boost factor (B) at low duty cycles. The proposed structure is analyzed under both ideal and non-ideal conditions. The non-ideal analysis considers parasitic components. The voltage drop across each element is calculated. A detailed analysis of component voltage and current behavior is provided. Furthermore, a power loss analysis and design considerations are discussed, taking into account the influence of parasitic elements. A comprehensive comparison is conducted, evaluating various parameters such as voltage and current stress, boost factor, and efficiency. Additionally, a cost analysis comparing the proposed structure with conventional designs is provided under equivalent conditions. The experimental results obtained under different conditions are presented to validate the theoretical analysis, particularly in realistic scenarios.

Design and Analysis of an Origami-Inspired Modular Gripper for Non-Cooperative Target Space Capture

Abstract Aiming to capture the needs of non-cooperative targets in space missions, this research proposes a modular design scheme for a space capture gripper in combination with origami theory and carries out a corresponding capture performance analysis for the proposed gripper configuration. First, the finger unit module is formed by the configuration design of the Miura crease through origami theory. A variety of gripper configurations are formed through the hinge offset technique. The mobility of the selected gripper configurations is analyzed, and a single-degree-of-freedom finger drive implementation is proposed. Second, numerical analysis is carried out to investigate and validate the kinematic characteristics through a computer-aided design model. In order to evaluate the performance of the gripper, the mapping relationship between key design parameters and performance indicators such as envelope radius and envelope space is investigated. Considering the gripper's geometric constraints and performance indexes, its optimal capturing posture is analyzed. Finally, the correctness of the theoretical analysis is verified by the prototype model, and it is shown that the origami-inspired modular gripper has the advantages of simple structure, easy control, and high versatility. The gripper can be used to capture non-cooperative targets in space missions, which provides a certain reference for the application of origami theory in engineering.

Field-induced spin liquid in the decorated square-kagome antiferromagnet nabokoite KCu7TeO4(SO4)5Cl

Quantum antiferromagnets based on the square-kagome lattice are proving to be a fertile platform for realizing nontrivial phenomena in frustrated magnetism. Recently, several decorated square-kagome compounds of the nabokoite family have been synthesized, allowing for experimental exploration of model Hamiltonians. Here, we carry out a theoretical analysis of KCu7TeO4(SO4)5Cl nabokoite using a Heisenberg Hamiltonian derived from density functional theory energy mapping. We employ classical Monte Carlo simulations to explain the two transitions experimentally observed in the low-temperature magnetization curve. Interestingly, the intermediate-field phase is also found in a purely two-dimensional model and is described by a spin liquid featuring subextensive degeneracy with a ferrimagnetic component. We show that this phase can be approximated by a checkerboard lattice in a magnetic field. Finally, we assess the effects of quantum fluctuations in zero fields using the pseudo-Majorana functional renormalization group method.

Side‐Chain Engineering of Nickel Naphthalocyanine‐Based Hole‐Transport Materials Realizes >25% Efficiency and Light‐Heat Durable Perovskite Solar Cells

AbstractHole‐transport materials (HTMs) play an essential role in governing both the efficiency and stability of perovskite solar cells (PSCs). However, it still remains challenging to satisfy these two aspects simultaneously in n–i–p structured PSCs. Here, for the first time, the application of nickel naphthalocyanine (NiNc)‐based HTMs in PSCs is reported. Three NiNc derivatives, namely BuO‐NiNc, HeO‐NiNc, and OcO‐NiNc, are synthesized by modulating the length of alkoxy substituents. The impacts of the alkoxy side‐chain length on the molecular ordering, hole‐transport property, and film morphology of NiNcs are systematically investigated. Comprehensive experimental and theoretical analyses disclose that hexyloxy‐substituted NiNc (HeO‐NiNc) exhibits highly ordered molecular packing and stronger intermolecular interactions, resulting in superior hole transport characteristics. This leads to a champion power conversion efficiency (PCE) of 25.23% for HeO‐NiNc‐based devices, which is the record efficiency reported for metal complex‐based HTMs in PSCs. Moreover, the encapsulated devices employing HeO‐NiNc also exhibit outstanding photo‐thermal durability, retaining over 81% after 1008 h under continuous 1‐sun irradiation at 85 °C (ISOS‐L‐2 protocol). This represents one of the best light‐heat stability among n–i–p PSCs with >25% PCE. This work offers new routes for the development of HTMs in PSCs that simultaneously combine high efficiency and high long‐term stability.

Current Sharing Network‐Based Bidirectional DC–DC Converter With High Conversion Ratio

ABSTRACTThe increasing demand for electric vehicles necessitates advancements in efficient and compact on‐board charging systems. This paper presents a bidirectional DC–DC converter with a high voltage conversion ratio based on an inductor current‐sharing network for on‐board charger applications. The proposed converter features a simple structural, reduced inductor size, and fewer components while achieving significant voltage gain in both step‐up and step‐down modes. The converter's performance is rigorously evaluated through detailed theoretical analysis and simulation. A comprehensive comparison with recent converter topologies is provided, demonstrating the proposed design's distinct advantages. Additionally, a steady‐state analysis is included. To validate the concept, a 500 W prototype is developed, and experimental results at a 50 kHz switching frequency are presented, confirming the effectiveness and potential of the proposed bidirectional converter.

DELBO: Efficient score algorithm for feature selection on latent variables of VAE.

In this paper, we develop the notion of the difference of evidence lower bounds (DELBO), based on which an efficient score algorithm is presented to implement feature selection on latent variables of VAE and its variants. Furthermore, we propose marginalization approximation algorithms to optimize VAE-related models by weighting the "more important" latent variables selected and accordingly increasing evidence lower bound. We discuss two kinds of different Gaussian posteriors, mean-field and full-covariance, for latent variables, and make the corresponding theoretical analyses to support the effectiveness of algorithms. Plenty of comparative experiments are carried out between our algorithms and the other 9 feature selection methods on 7 public datasets to address generative tasks. The results demonstrate the superior performance of our algorithms. Finally, we extend DELBO to its generalized version and apply the latter to tackling classification tasks of 5 new public datasets with satisfactory experimental results.

Research on a Two-Dimensional Model of Customer Satisfaction

Background and Aim： Important topics in service management theory research include customer orientation, reducing customer complaints, and pursuing customer satisfaction. The majority of customer satisfaction surveys and analyses overlook the effect of the discrete distribution of each evaluation item on the overall uncertainty of customer satisfaction evaluation, which makes it challenging to provide thorough and accurate information. Currently, customer satisfaction surveys are widely used to quantitatively evaluate service quality. Simultaneously, the quality of service provided by college student apartments will impact social and campus stability, so analyzing satisfaction metrics is crucial. This paper aims to (1) establish a two-dimensional indicator model for customer satisfaction and perceived quality standard deviation, expanding the single dimension into two dimensions, and (2) improve the service of college student apartments to avoid the occurrence of crisis events. Methodology: The study employs a rigorous quantitative approach, supported by theoretical analysis and validated through iterative testing of the questionnaire. This ensures the conceptual model is robust, and the final survey instrument is both reliable and valid for comprehensive data collection. Results: This study identifies current issues, presents the concept of standard deviation based on accepted theories of customer satisfaction and service quality, and summarizes research findings in customer satisfaction, service quality, customer complaints, etc. Customer satisfaction (CS) is the first dimension in a two-dimensional model of customer satisfaction, and perceived quality standard deviation (SD) is the second dimension. For a more thorough assessment of customer satisfaction, a "four-interval" chart is suggested. This study developed a two-dimensional model of customer satisfaction for college student apartments using expert interviews and statistical analysis. This study simultaneously screened and processed the actual survey questionnaire data, developed a data processing program, and proposed a mathematical model. Conclusion: In addition to conducting a correlation analysis between customer satisfaction, quality standard deviation, and the number of student complaints in college student apartments, this study shows how effective a two-dimensional model for customer satisfaction is in these settings.

Basic acceleration technique with theoretical analysis on iterative algorithms for image reconstruction.

In image reconstruction and processing, incorporating prior information, particularly the nonnegativity of pixel values, is essential. Existing computed tomography (CT) iterative reconstruction algorithms, including the algebraic reconstruction technique (ART), simultaneous ART (SART), and the simultaneous iterative reconstruction technique (SIRT), typically address negative components during the iteration process by either setting them to zero, introducing regularization terms to prevent negativity, or leaving them unchanged. This paper establishes a general framework in which enforcing the nonnegativity prior accelerates the convergence of the reconstructed image toward the true solution. Within this framework, we propose two efficient and simple acceleration techniques: setting negative pixel values to their absolute values and updating them to the estimated values from the previous update. Experiments were conducted using ART, SIRT, and SART algorithms, integrated with the corresponding acceleration techniques, on full-angle, limited-angle, and noisy simulated data, as well as real data. The results validate the effectiveness of the proposed acceleration methods by evaluating image quality using the PSNR and SSIM metrics. Notably, the proposed technique that sets negative pixel values to their absolute values is strongly recommended, as it significantly outperforms the existing technique that sets them to zero, both in terms of image quality and iteration time.

Design and optimization of honeycomb structure in dual-link mechanism for revolving two-wing doors

This research puts forward a retractable dual-link mechanism to alleviate revolving two-wing doors collision risks. The mechanism is composed of three key parts: dual linkages, a base plate, and a connector. Through theoretical analysis and structural topology optimization with the goal of mass minimization, the existing constraints in traditional optimization methods that undermine structural integrity have been revealed. To resolve this issue, a trapezoid honeycomb structure has been designed as a substitute for the substrate. This design has achieved an 18.8% reduction in weight while preserving mechanical performance. Quasi-static compression tests and simulations have been employed to verify the energy absorption capacity and deformation characteristics of the honeycomb structure under significant impact loads. This comprehensive approach offers a novel solution for enhancing pedestrian safety.

ÉTICA NA EDUCAÇÃO: FUNDAMENTOS TEÓRICOS E A RESPONSABILIDADE COMPARTILHADA NA FORMAÇÃO DE VALORES

ABSTRACT This article presents a theoretical analysis of the importance of ethics in education, highlighting the shared responsibility among teachers, students, parents, and school administrators in the formation of values. It addresses fundamental concepts of ethics, their relationship with education, and strategies for the development of ethical behaviors in the school environment. This is an ongoing research project and forms part of the theoretical foundation of a master’s thesis in education, which investigates the formation of values in children’s attitudes, the role of parents in this process, and the training of teachers to promote ethics in everyday school life. As an initial methodology, a theoretical study was conducted with a time frame from 2020 to 2024, aiming to understand how the topic has been addressed in recent years in Brazilian academic publications. As a partial result, the research indicated that the theme is sparsely addressed in the Brazilian context. Keywords: Ethics in education; values; shared responsibility; teacher training; elementary school.

Physico-metallic characteristics of waters from gold mining in the locality of Djouzami (Adamawa, Cameroon) and adsorption of iron(II) by a filter made from sand coated with bimetallic iron–manganese oxide: modeling and theoretical analysis

Physico-metallic characteristics of waters from gold mining in the locality of Djouzami (Adamawa, Cameroon) and adsorption of iron(II) by a filter made from sand coated with bimetallic iron–manganese oxide: modeling and theoretical analysis

Thermal–Electrical Optimization of Lithium-Ion Battery Conductor Structures Under Extreme High Amperage Current

This study addresses the critical challenges of conductor structure fusing, thermal management failure, and thermal runaway risks in lithium-ion batteries under extreme high-amperage discharge conditions. By integrating theoretical analysis, multiphysics coupling simulations, and experimental validation, the research systematically investigates the overcurrent capability of lithium battery conductor structures. A novel current–thermal structure coupled finite element model was developed to analyze the dynamic relationship between key parameters, specifically overcurrent cross-sectional area and contact area, and their influence on temperature gradient distribution. Experimental results confirm the model’s accuracy, revealing that under extreme high-amperage conditions, increasing the conductor cross-sectional area by 50% only marginally extends the battery’s current-carrying duration from 0.75 s to 0.8 s. This limited enhancement is attributed to rapid heat generation, which restricts the effectiveness of increasing the cross-sectional area alone. Instead, optimizing the conductor structure by modifying the heat conduction path, which involves a similar increase in the cross-sectional area and an additional 60% increase in contact area through the addition of a welding reinforcement structure, achieves thermal equilibrium. The optimized design achieves a current-carrying duration of 1.73 s, which is 230% of the duration of the traditional configuration. This work establishes a scalable framework for enhancing the thermal–electrical performance of lithium-ion batteries, providing a theoretical foundation for structural optimization and offering significant methodological support for advancing research in high-power battery design, with potential applications in electric vehicles, renewable energy systems, and industrial robotics.

The doctrine of the legal process and its types (general theoretical analysis)

Relevance. This article provides an overview of scientific approaches to the definition of the legal process in general and the constituent process in particular. Attention is drawn to the fact that, despite the solid scientific background, the problems of establishing the essential and substantive characteristics of the legal process, as well as the definition of its concept, have not yet been resolved; the discussion on these issues continues.The purpose is to form a holistic scientific understanding of the legal process. Objectives: to analyze approaches to the definition of a legal process; to identify its features; to define the concept and consider the grounds for classifying a legal process.Methodology. A system-activity approach was applied to the definition of the concept and essence of the legal process, which made it possible to reveal it as a complex dynamic functionally active phenomenon consisting of interacting elements, integrating them with appropriate goals, means and results in correlation with effectiveness.Results. It is proposed to distinguish between jurisdictional processes related exclusively to legal proceedings and other, positive, but also legal processes that mediate legal activity in all its varieties. The classification of the legal process is substantiated, which is based on the subject-functional feature and the orientation of the non-regulatory impact of a particular sphere of public relations. According to this criterion, the constituent legal process, law-making and law enforcement are distinguished.Conclusion. The conducted research makes it possible to define the legal process as a specific legal education as part of the normatively established, procedural, and professional activities of authorized subjects aimed at the successful implementation of the goals of legal activity in order to obtain a socially significant result that meets the needs and interests of the individual, society, and the state. The proposed conclusions will to a certain extent contribute to the further development of the theory of the legal process, a scientific category that is in full demand by science and practice.

A Method for the Evaluation of Crack Tip Opening Loads Based on Strip Yield Modeling of a Propagating Crack

ABSTRACTBased on the strip yield model for propagating cracks, the current paper proposes a new method for the evaluation of crack tip opening loads. It is based on the theoretical analysis of shapes of the compliance offset curves for various applied stress levels and R ratios, which indicates that the inflection point of the curve is a good approximation of the initiation of the crack tip opening. The method avoids uncertainties and drawbacks associated with the selection of empirical thresholds or criteria to identify the value of the opening load, which is often utilized to calculate the effective stress intensity factor range or fatigue crack driving force. Careful experimental studies also confirm the ability of this proposed method to negate the R ratio effect on fatigue crack growth rates for a wide range of loading conditions.

Analysis of the impact of rock joint cracks on blastability of burnt rock in Xinjiang open pit coal mines

In response to the problems of developed rock fractures and unsatisfactory bench blasting effects in open-pit coal mines in Xinjiang, China, By using on-site research, theoretical analysis, numerical simulation and other methods, the main influencing factors of burnt rock blasting are analyzed, and the impact of joint cracks in burnt rock on its blastability is quantitatively evaluated and graded. Research shows: the main influencing factors on the blastability of burnt rock are the density of original rock joint fractures, the length of original rock joint fractures, the radius of crack propagation after blasting, and the peak blasting stress. We have established quantitative mathematical models for various influencing factors, established a classification evaluation model and evaluation standards for the blastability of burnt rocks in Xinjiang region. The comprehensive evaluation index G of blastability is divided into five levels: Level I (G > 20.7) extremely easy to blast, Level II (G = 16.7–20.7) easy to blast, Level III (G = 12.7–16.6) difficult to blast, Level IV (G = 8.7–12.6) difficult to blast, and Level V (G < 8.7) extremely difficult to blast. And a study was conducted on the blastability evaluation and classification of burnt rocks in six open-pit coal mines in Xinjiang region, and the results of blastability classification were obtained: open-pit mine 1: G = 13.3 is level III difficult to blast, open-pit mine 2: G = 13.0 is level III difficult to blast, open-pit mine 3: G = 13.3 is level III difficult to blast, open-pit mine 4: G = 13.1 is level III difficult to blast, open-pit mine 5: G = 12.8 is level III difficult to blast, and open-pit mine 6: G = 12.5 is level IV difficult to blast.

Deciphering the Structural and Electronic Properties of RuSi3-/0 Clusters: Insights from Anion Photoelectron Spectroscopy and Theoretical Analysis.

Transition metal (TM) silicides have attracted significant attention in materials science due to their desirable physical properties and varied applications across industries ranging from microelectronics to catalysis. This study uniquely explores the structural and bonding characteristics of ruthenium-doped silicon clusters, specifically RuSi3, presenting new experimental and computational insights into these anionic and neutral species. Mass-selected photoelectron spectroscopy, alongside advanced theoretical techniques including density functional theory (DFT) and high-precision coupled cluster (CCSD(T)) methods, was employed to probe the electronic structures and energetic properties of RuSi3- anion and its neutral counterpart. The results reveal the presence of multiple isomers within RuSi3-, characterized by distinct electronic configurations, and show a strong correlation between experimental and theoretical vertical detachment energy (VDE). Notably, the findings indicate that the covalent interactions and charge distributions in these clusters significantly influence their stability and reactivity.

Pulse interval tunable terahertz radiation from electron beam-plasma interactions

Abstract Terahertz (THz) radiation is rapidly emerging as a powerful tool with diverse applications, including high-speed imaging, laser-driven particle acceleration, and ultra-high frequency (UHF) communications. However, generating multipulse THz radiation with controllable time intervals remains a significant challenge. This study presents a approach to overcome this hurdle by exploiting the interaction between an electron beam and plasma. Using numerical simulations and theoretical analysis, we investigated the behavior of an electron beam within a plasma and its interaction with the longitudinal sheath field. This interaction resulted in the generation of multiple distinct THz pulses. We demonstrated that the plasma length adjustment allows for precise tuning of the interval between THz pulses. Moreover, the radiation intensity could be controlled by the electron beam energy and the electron bunch duration. The proposed scheme can generate multi-pulse THz radiation in a flexible and precise manner, paving the way for advancements in applications requiring high temporal resolution.