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Keywords = nonlinear reaction

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14 pages, 6012 KiB  
Article
Decoding the Primacy of Transportation Emissions of Formaldehyde Pollution in an Urban Atmosphere
by Shi-Qi Liu, Hao-Nan Ma, Meng-Xue Tang, Yu-Ming Shao, Ting-Ting Yao, Ling-Yan He and Xiao-Feng Huang
Toxics 2025, 13(8), 643; https://doi.org/10.3390/toxics13080643 - 30 Jul 2025
Viewed by 234
Abstract
Understanding the differential impacts of emission sources of volatile organic compounds (VOCs) on formaldehyde (HCHO) levels is pivotal to effectively mitigating key photochemical radical precursors, thereby enhancing the regulation of atmospheric oxidation capacity (AOC) and ozone formation. This investigation systematically selected and analyzed [...] Read more.
Understanding the differential impacts of emission sources of volatile organic compounds (VOCs) on formaldehyde (HCHO) levels is pivotal to effectively mitigating key photochemical radical precursors, thereby enhancing the regulation of atmospheric oxidation capacity (AOC) and ozone formation. This investigation systematically selected and analyzed year-long VOC measurements across three urban zones in Shenzhen, China. Photochemical age correction methods were implemented to develop the initial concentrations of VOCs before source apportionment; then Positive Matrix Factorization (PMF) modeling resolved six primary sources: solvent usage (28.6–47.9%), vehicle exhaust (24.2–31.2%), biogenic emission (13.8–18.1%), natural gas (8.5–16.3%), gasoline evaporation (3.2–8.9%), and biomass burning (0.3–2.4%). A machine learning (ML) framework incorporating Shapley Additive Explanations (SHAP) was subsequently applied to evaluate the influence of six emission sources on HCHO concentrations while accounting for reaction time adjustments. This machine learning-driven nonlinear analysis demonstrated that vehicle exhaust nearly always emerged as the primary anthropogenic contributor in diverse functional zones and different seasons, with gasoline evaporation as another key contributor, while the traditional reactivity metric method, ozone formation potential (OFP), tended to underestimate the role of the two sources. This study highlights the primacy of strengthening emission reduction of transportation sectors to mitigate HCHO pollution in megacities. Full article
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14 pages, 268 KiB  
Article
Stability Analysis of Biological Systems Under Threshold Conditions
by Jannat E Mahbuba and Xiang-Sheng Wang
Symmetry 2025, 17(8), 1193; https://doi.org/10.3390/sym17081193 - 25 Jul 2025
Viewed by 174
Abstract
In biological models exhibiting symmetric interactions within each compartmental group, threshold dynamics are typically governed by a key parameter known as the basic reproduction number R0. The stability of an equilibrium often hinges on whether R0 is greater than or [...] Read more.
In biological models exhibiting symmetric interactions within each compartmental group, threshold dynamics are typically governed by a key parameter known as the basic reproduction number R0. The stability of an equilibrium often hinges on whether R0 is greater than or less than one. However, general results for stability at the critical threshold—when R0 equals one—remain scarce. In this paper, we establish two theorems to analyze the stability of both trivial and boundary equilibria under this threshold condition. Our results provide explicit expressions for the threshold parameters in terms of partial derivatives of the nonlinear reaction function, making them readily applicable to a wide range of biological systems. Full article
(This article belongs to the Special Issue Symmetry/Asymmetry of Differential Equations in Biomathematics)
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13 pages, 1895 KiB  
Article
Class-Dependent Solar Flare Effects on Mars’ Upper Atmosphere: MAVEN NGIMS Observations of X8.2 and M6.0 from September 2017
by Junaid Haleem and Shican Qiu
Universe 2025, 11(8), 245; https://doi.org/10.3390/universe11080245 - 25 Jul 2025
Viewed by 226
Abstract
Transient increments of X-ray radiation and extreme ultraviolet (EUV) during solar flares are strong drivers of thermospheric dynamics on Mars, yet their class-dependent impacts remain poorly measured. This work provides the first direct, side-by-side study of Martian thermospheric reactions to flares X8.2 on [...] Read more.
Transient increments of X-ray radiation and extreme ultraviolet (EUV) during solar flares are strong drivers of thermospheric dynamics on Mars, yet their class-dependent impacts remain poorly measured. This work provides the first direct, side-by-side study of Martian thermospheric reactions to flares X8.2 on 10 September 2017 and M6.0 on 17 September 2017. This study shows nonlinear, class-dependent effects, compositional changes, and recovery processes not recorded in previous investigations. Species-specific responses deviated significantly from irradiance proportionality, even though the soft X-ray flux in the X8.2 flare was 13 times greater. Argon (Ar) concentrations rose 3.28× (compared to 1.13× for M6.0), and radiative cooling led CO2 heating to approach a halt at ΔT = +40 K (X8.2) against +19 K (M6.0) at exobase altitudes (196–259 km). N2 showed the largest class difference, where temperatures rose by +126 K (X8.2) instead of +19 K (M6.0), therefore displaying flare-magnitude dependent thermal sensitivity. The 1.95× increase in O concentrations during X8.2 and the subsequent decrease following M6.0 (−39 K cooling) illustrate the contradiction between photochemical production and radiative loss. The O/CO2 ratio at 225 km dropped 46% during X8.2, revealing compositional gradients boosted by flares. Recovery timeframes varied by class; CO2 quickly re-equilibrated because of effective cooling, whereas inert species (Ar, N2) stabilized within 1–2 orbits after M6.0 but needed >10 orbits of the MAVEN satellite after the X8.2 flare. The observations of the X8.2 flare came from the western limb of the Sun, but the M6.0 flare happened on the far side. The CME shock was the primary driver of Mars’ EUV reaction. These findings provide additional information on atmospheric loss and planetary habitability by indicating that Mars’ thermosphere has a saturation threshold where strong flares induce nonlinear energy partitioning that encourages the departure of lighter species. Full article
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20 pages, 873 KiB  
Article
A Mixed Finite Volume Element Method for Nonlinear Time Fractional Fourth-Order Reaction–Diffusion Models
by Jie Zhao, Min Cao and Zhichao Fang
Fractal Fract. 2025, 9(8), 481; https://doi.org/10.3390/fractalfract9080481 - 23 Jul 2025
Viewed by 204
Abstract
In this paper, a linearized mixed finite volume element (MFVE) scheme is proposed to solve the nonlinear time fractional fourth-order reaction–diffusion models with the Riemann–Liouville time fractional derivative. By introducing an auxiliary variable σ=Δu, the original fourth-order model is [...] Read more.
In this paper, a linearized mixed finite volume element (MFVE) scheme is proposed to solve the nonlinear time fractional fourth-order reaction–diffusion models with the Riemann–Liouville time fractional derivative. By introducing an auxiliary variable σ=Δu, the original fourth-order model is reformulated into a lower-order coupled system. The first-order time derivative and the time fractional derivative are discretized by using the BDF2 formula and the weighted and shifted Grünwald difference (WSGD) formula, respectively. Then, a fully discrete MFVE scheme is constructed by using the primal and dual grids. The existence and uniqueness of a solution for the MFVE scheme are proven based on the matrix theories. The scheme’s unconditional stability is rigorously derived by using the Gronwall inequality in detail. Moreover, the optimal error estimates for u in the discrete L(L2(Ω)) and L2(H1(Ω)) norms and for σ in the discrete L2(L2(Ω)) norm are obtained. Finally, three numerical examples are given to confirm its feasibility and effectiveness. Full article
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19 pages, 2215 KiB  
Article
Evaluation of the Effectiveness of Driver Training in the Use of Advanced Driver Assistance Systems
by Małgorzata Pełka and Adam Rosiński
Appl. Sci. 2025, 15(15), 8169; https://doi.org/10.3390/app15158169 - 23 Jul 2025
Viewed by 208
Abstract
This paper evaluates the effectiveness of driver training programmes aimed at the proper use of Advanced Driver Assistance Systems (ADASs). Participants (N = 49) were divided into the following three groups based on the type of training received: practical training, e-learning, and brief [...] Read more.
This paper evaluates the effectiveness of driver training programmes aimed at the proper use of Advanced Driver Assistance Systems (ADASs). Participants (N = 49) were divided into the following three groups based on the type of training received: practical training, e-learning, and brief manual instruction. The effectiveness of the training methods was assessed using selected parameters obtained from driving simulator studies, including reaction times and system activation attempts. Given the large volume and nonlinear nature of the input data, a heuristic, expert-based approach was used to identify key evaluation criteria, structure the decision-making process, and define fuzzy rule sets and membership functions. This phase served as the foundation for the development of a fuzzy logic model in the MATLAB environment. The model processes inputs to generate a quantitative performance score. The results indicate that practical training (mean score = 4.0) demonstrates superior effectiveness compared to e-learning (3.09) and manual instruction (mean score = 3.01). The primary contribution of this work is a transparent, data-driven evaluation tool that overcomes the inherent subjectivity and bias of traditional trainer-based assessments. This model provides a standardised and reproducible approach for assessing driver competence, offering a significant advancement over purely qualitative, trainer-based assessments and supporting the development of more reliable certification processes. Full article
(This article belongs to the Section Transportation and Future Mobility)
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14 pages, 2182 KiB  
Article
Stability Analysis of a Master–Slave Cournot Triopoly Model: The Effects of Cross-Diffusion
by Maria Francesca Carfora and Isabella Torcicollo
Axioms 2025, 14(7), 540; https://doi.org/10.3390/axioms14070540 - 17 Jul 2025
Viewed by 164
Abstract
A Cournot triopoly is a type of oligopoly market involving three firms that produce and sell homogeneous or similar products without cooperating with one another. In Cournot models, firms’ decisions about production levels play a crucial role in determining overall market output. Compared [...] Read more.
A Cournot triopoly is a type of oligopoly market involving three firms that produce and sell homogeneous or similar products without cooperating with one another. In Cournot models, firms’ decisions about production levels play a crucial role in determining overall market output. Compared to duopoly models, oligopolies with more than two firms have received relatively less attention in the literature. Nevertheless, triopoly models are more reflective of real-world market conditions, even though analyzing their dynamics remains a complex challenge. A reaction–diffusion system of PDEs generalizing a nonlinear triopoly model describing a master–slave Cournot game is introduced. The effect of diffusion on the stability of Nash equilibrium is investigated. Self-diffusion alone cannot induce Turing pattern formation. In fact, linear stability analysis shows that cross-diffusion is the key mechanism for the formation of spatial patterns. The conditions for the onset of cross-diffusion-driven instability are obtained via linear stability analysis, and the formation of several Turing patterns is investigated through numerical simulations. Full article
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18 pages, 2623 KiB  
Article
Beta Diversity Patterns and Drivers of Macroinvertebrate Communities in Major Rivers of Ningxia, China
by Qiangqiang Yang, Zeyu Wei, Xiaocong Qiu and Zengfeng Zhao
Animals 2025, 15(14), 2034; https://doi.org/10.3390/ani15142034 - 10 Jul 2025
Viewed by 358
Abstract
The clarification of community assembly mechanisms in benthic macroinvertebrates and their respective contributions to the development of beta diversity is a fundamental concern in aquatic ecology. Nonetheless, the intrinsic complexity of community alterations and their non-linear reactions to gradients of explanatory variables present [...] Read more.
The clarification of community assembly mechanisms in benthic macroinvertebrates and their respective contributions to the development of beta diversity is a fundamental concern in aquatic ecology. Nonetheless, the intrinsic complexity of community alterations and their non-linear reactions to gradients of explanatory variables present considerable obstacles to measuring the determinants of beta diversity. Fifty sampling points were set up along the major rivers of the Yellow River Irrigation Area (YRIA), the Central Arid Zone (CAZ), and the Southern Mountainous Area (SMA) in Ningxia in April, July, and October 2023. The findings demonstrate that the optimal parameter-based geographical detector (OPGD) model identified a 3000 m circular buffer as the spatial scale at which landscape structure most significantly influences water quality. A degradation in water quality presumably results in diminished differences in species composition among communities. The Sørensen index was determined to be more appropriate for this investigation, and the total beta diversity of the communities was relatively high (βSOR ≥ 0.82), with no identifiable nested spatial patterns detected. Except in the YRIA, environmental variability contributed more significantly to the variance in beta diversity than spatial factors, and deterministic mechanisms dominated the community assembly of benthic macroinvertebrates across all three months. To improve biodiversity and aquatic ecosystem health, the study region should optimize its landscape structure by reducing the amount of bare land and increasing the percentage of forest land within buffer zones. Additionally, a multi-site conservation strategy should be put into place. Full article
(This article belongs to the Section Ecology and Conservation)
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24 pages, 5097 KiB  
Article
Non-Monotonic Effect of Substrate Inhibition in Conjunction with Diffusion Limitation on the Response of Amperometric Biosensors
by Romas Baronas
Biosensors 2025, 15(7), 441; https://doi.org/10.3390/bios15070441 - 9 Jul 2025
Viewed by 254
Abstract
The non-monotonic behavior of amperometric enzyme-based biosensors under uncompetitive and noncompetitive (mixed) substrate inhibition is investigated computationally using a two-compartment model consisting of an enzyme layer and an outer diffusion layer. The model is based on a system of reaction–diffusion equations that includes [...] Read more.
The non-monotonic behavior of amperometric enzyme-based biosensors under uncompetitive and noncompetitive (mixed) substrate inhibition is investigated computationally using a two-compartment model consisting of an enzyme layer and an outer diffusion layer. The model is based on a system of reaction–diffusion equations that includes a nonlinear term associated with non-Michaelis–Menten kinetics of the enzymatic reaction and accounts for the partitioning between layers. In addition to the known effect of substrate inhibition, where the maximum biosensor current differs from the steady-state output, it has been determined that external diffusion limitations can also cause the appearance of a local minimum in the current. At substrate concentrations greater than both the Michaelis–Menten constant and the uncompetitive substrate inhibition constant, and in the presence of external diffusion limitation, the transient response of the biosensor, after immersion in the substrate solution, may follow a five-phase pattern depending on the model parameter values: it starts from zero, reaches a global or local maximum, decreases to a local minimum, increases again, and finally decreases to a steady intermediate value. The biosensor performance is analyzed numerically using the finite difference method. Full article
(This article belongs to the Special Issue Novel Designs and Applications for Electrochemical Biosensors)
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16 pages, 5185 KiB  
Article
Analysis the Mechanical Response of Tunnels Under the Action of Vertical Jacking in Shield Construction and Research on Reinforcement
by Mingxun Hou, Chunshan Yang, Jiayi Yang, Yuefei Zeng and Zhigang Zhu
Buildings 2025, 15(13), 2321; https://doi.org/10.3390/buildings15132321 - 2 Jul 2025
Viewed by 247
Abstract
This research examines the effects of vertical jacking construction on the mechanical behavior of shield tunnels. Model tests simulating vertical jacking were performed utilizing a purpose-built apparatus to quantify the reaction forces generated by the diffusion block during the jacking operation. A systematic [...] Read more.
This research examines the effects of vertical jacking construction on the mechanical behavior of shield tunnels. Model tests simulating vertical jacking were performed utilizing a purpose-built apparatus to quantify the reaction forces generated by the diffusion block during the jacking operation. A systematic analysis was conducted on the mechanical responses of shield tunnel lining segments and their interconnecting joints. Utilizing Particle Flow Code (PFC) methodology, a deformation prediction model specifically tailored for vertical jacking conditions was formulated. Correlating simulation results with experimental measurements quantified the sensitivity of tunnel deformation to grouting reinforcement, enabling the identification of an optimal reinforcement zone. Key findings reveal that the jacking reaction force distribution exhibits pronounced nonlinearity: a substantial increase precedes failure, followed by rapid post-failure reduction and eventual stabilization in advanced jacking stages. Tunnel convergence deformation evolves through four distinct phases: significant growth, rapid attenuation, gradual diminution, and final stabilization. The primary zone of influence encompasses the opening ring and its two adjacent rings. Jacking induces longitudinal bending deformation, with maximum joint opening occurring at the opening ring. Abrupt longitudinal load fluctuations cause dislocation between the opening ring and neighboring rings. Internal segment stresses exhibit initial tensile and compressive increases followed by subsequent relaxation. Externally applied grouting reinforcement effectively attenuates jacking-induced tunnel deformation. An optimal reinforcement range was determined at the 60° position relative to the segment springline, substantially lowering resource consumption and construction risks compared to conventional reinforcement strategies. These outcomes furnish theoretical underpinnings and technical benchmarks for optimizing engineering design and facilitating the implementation of vertical jacking technology. Full article
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15 pages, 1033 KiB  
Article
Detrended Fluctuation Analysis of Gait Cycles: A Study of Neuromuscular and Ground Force Dynamics
by Soumya Prakash Rana and Maitreyee Dey
Sensors 2025, 25(13), 4122; https://doi.org/10.3390/s25134122 - 2 Jul 2025
Viewed by 403
Abstract
Gait analysis provides crucial insights into neuromuscular coordination and postural control, especially in ageing populations and rehabilitation contexts. This study investigates the complexity of muscle activation and ground reaction force patterns during gait by applying detrended fluctuation analysis (DFA) to electromyography (EMG) and [...] Read more.
Gait analysis provides crucial insights into neuromuscular coordination and postural control, especially in ageing populations and rehabilitation contexts. This study investigates the complexity of muscle activation and ground reaction force patterns during gait by applying detrended fluctuation analysis (DFA) to electromyography (EMG) and force-sensitive resistor (FSR) signals. Data from a two-arm randomised clinical trial (RCT) supplemented with an observational control group were used in this study. Participants performed a single-task walking protocol, with EMG recorded from the tibialis anterior and lateral gastrocnemius muscles of both legs and FSR sensors placed under the feet. Gait cycles were segmented using heel-strike detection from the FSR signal, enabling analysis of individual strides. For each gait cycle, DFA was applied to quantify the long-range temporal correlations in the EMG and FSR time series. Results revealed consistent α-scaling exponents across cycles, with EMG signals exhibiting moderate persistence (α0.850.92) and FSR signals showing higher persistence (α1.5), which is indicative of stable and repeatable gait patterns. These findings support the utility of DFA as a nonlinear signal processing tool for characterising gait dynamics, offering potential markers for gait stability, motor control, and intervention effects in populations practising movement-based therapies such as Tai Chi. Future work will extend this analysis to dual-task conditions and comparative group studies. Full article
(This article belongs to the Special Issue Feature Papers in the 'Sensor Networks' Section 2025)
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19 pages, 2636 KiB  
Article
Poly(pyridinium salt)s Containing 9,9-Bis(4-aminophenyl)fluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties
by Pradip K. Bhowmik, David King, Haesook Han, András F. Wacha and Matti Knaapila
Polymers 2025, 17(13), 1785; https://doi.org/10.3390/polym17131785 - 27 Jun 2025
Viewed by 344
Abstract
Main-chain conjugated and non-conjugated polyelectrolytes are an important class of materials that have many technological applications ranging from fire-retardant materials to carbon-nanotube composites, nonlinear optical materials, electrochromic materials for smart windows, and optical sensors for biomolecules. Here, we describe a series of poly(pyridinium [...] Read more.
Main-chain conjugated and non-conjugated polyelectrolytes are an important class of materials that have many technological applications ranging from fire-retardant materials to carbon-nanotube composites, nonlinear optical materials, electrochromic materials for smart windows, and optical sensors for biomolecules. Here, we describe a series of poly(pyridinium salt)s-fluorene containing 9,9-bis(4-aminophenyl)fluorene moieties with various organic counterions that were synthesized using ring-transmutation polymerization and metathesis reactions, which are non-conjugated polyelectrolytes. Their chemical structures were characterized by Fourier transform infrared (FTIR), proton (1H) and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers, and elemental analysis. They exhibited polyelectrolytic behavior in dimethyl sulfoxide. Their lyotropic liquid-crystalline phases were examined by polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS) studies. Their emission spectra exhibited a positive solvatochromism on changing the polarity of solvents. They emitted greenish-yellow lights in polar organic solvents. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), whose λem peaks were blue shifted. Full article
(This article belongs to the Special Issue Smart Polymers for Stimuli-Responsive Devices)
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15 pages, 2564 KiB  
Article
Effect of CaO Content on the Photoluminescence Excitation and Emission Properties of Bi2O3 and ZnO-Co-Doped Ca2+xGa4O8+x Phosphors
by Shu-Han Liao, Xiang-Chen Cheng, Fang-Tzu Hsu, Cheng-Fu Yang and Tung-Lung Wu
Photonics 2025, 12(7), 625; https://doi.org/10.3390/photonics12070625 - 20 Jun 2025
Viewed by 262
Abstract
The synthesis process employed solid-state reaction methods to produce phosphors with varying CaO contents, specifically at x values of 0, 0.2, 0.4, 0.6, 0.8, and 1.0. As the CaO content (represented by the x value) increases, the crystalline structure of Ca2+x [...] Read more.
The synthesis process employed solid-state reaction methods to produce phosphors with varying CaO contents, specifically at x values of 0, 0.2, 0.4, 0.6, 0.8, and 1.0. As the CaO content (represented by the x value) increases, the crystalline structure of Ca2+xGa4O8+x + 0.01 Bi2O3 + 0.07 ZnO compositions underwent notable transformations. X-ray diffraction was used to characterize these structural changes, and we found that CaGa2O4, CaO, Ga2O3, and Ca3Ga4O9 were clearly identified. The diffraction intensities of CaGa2O4 and CaO phases increased and those of Ga2O3 and Ca3Ga4O9 decreased with the x value. Our findings revealed that the photoluminescence excitation (PLE) spectra consistently peak around 340 nm across all samples, while the photoluminescence emission (PL) spectra exhibited slight variations within the range of 474–477 nm. Most notably, the intensity of both PLE and PL spectra demonstrated a non-linear relationship with CaO content, initially increasing with higher CaO concentration, reaching maximum intensity at x = 0.4, and subsequently decreasing as the x value continued to rise. This research provides valuable insights into the relationship between composition, crystal structure, and luminescent behavior in Ca2+xGa4O8+x phosphor systems, and the theoretical mechanisms underlying these observed trends were thoroughly discussed. Full article
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26 pages, 1799 KiB  
Article
Comparative Study of the Nonlinear Fractional Generalized Burger-Fisher Equations Using the Homotopy Perturbation Transform Method and New Iterative Transform Method
by Mashael M. AlBaidani
Fractal Fract. 2025, 9(6), 390; https://doi.org/10.3390/fractalfract9060390 - 18 Jun 2025
Viewed by 472
Abstract
The time-fractional generalized Burger–Fisher equation (TF-GBFE) is utilized in many physical applications and applied sciences, including nonlinear phenomena in plasma physics, gas dynamics, ocean engineering, fluid mechanics, and the simulation of financial mathematics. This mathematical expression explains the idea of dissipation and shows [...] Read more.
The time-fractional generalized Burger–Fisher equation (TF-GBFE) is utilized in many physical applications and applied sciences, including nonlinear phenomena in plasma physics, gas dynamics, ocean engineering, fluid mechanics, and the simulation of financial mathematics. This mathematical expression explains the idea of dissipation and shows how advection and reaction systems can work together. We compare the homotopy perturbation transform method and the new iterative method in the current study. The suggested approaches are evaluated on nonlinear TF-GBFE. Two-dimensional (2D) and three-dimensional (3D) figures are displayed to show the dynamics and physical properties of some of the derived solutions. A comparison was made between the approximate and accurate solutions of the TF-GBFE. Simple tables are also given to compare the integer-order and fractional-order findings. It has been verified that the solution generated by the techniques given converges to the precise solution at an appropriate rate. In terms of absolute errors, the results obtained have been compared with those of alternative methods, including the Haar wavelet, OHAM, and q-HATM. The fundamental benefit of the offered approaches is the minimal amount of calculations required. In this research, we focus on managing the recurrence relation that yields the series solutions after a limited number of repetitions. The comparison table shows how well the methods work for different fractional orders, with results getting closer to precision as the fractional-order numbers get closer to integer values. The accuracy of the suggested techniques is greatly increased by obtaining numerical results in the form of a fast-convergent series. Maple is used to derive the approximate series solution’s behavior, which is graphically displayed for a number of fractional orders. The computational stability and versatility of the suggested approaches for examining a variety of phenomena in a broad range of physical science and engineering fields are highlighted in this work. Full article
(This article belongs to the Special Issue Fractional Mathematical Modelling: Theory, Methods and Applications)
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22 pages, 4653 KiB  
Article
Recycled Clay Brick Powder as a Dual-Function Additive: Mitigating the Alkali–Silica Reaction (ASR) and Enhancing Strength in Eco-Friendly Mortar with Hybrid Waste Glass and Clay Brick Aggregates
by Xue-Fei Chen, Xiu-Cheng Zhang and Ying Peng
Materials 2025, 18(12), 2838; https://doi.org/10.3390/ma18122838 - 16 Jun 2025
Viewed by 457
Abstract
The construction industry’s escalating environmental footprint, coupled with the underutilization of construction waste streams, necessitates innovative approaches to sustainable material design. This study investigates the dual functionality of recycled clay brick powder (RCBP) as both a supplementary cementitious material (SCM) and an alkali–silica [...] Read more.
The construction industry’s escalating environmental footprint, coupled with the underutilization of construction waste streams, necessitates innovative approaches to sustainable material design. This study investigates the dual functionality of recycled clay brick powder (RCBP) as both a supplementary cementitious material (SCM) and an alkali–silica reaction (ASR) inhibitor in hybrid mortar systems incorporating recycled glass (RG) and recycled clay brick (RCB) aggregates. Leveraging the pozzolanic activity of RCBP’s residual aluminosilicate phases, the research quantifies its influence on mortar durability and mechanical performance under varying substitution scenarios. Experimental findings reveal a nonlinear relationship between RCBP dosage and mortar properties. A 30% cement replacement with RCBP yields a 28-day activity index of 96.95%, confirming significant pozzolanic contributions. Critically, RCBP substitution ≥20% effectively mitigates ASRs induced by RG aggregates, with optimal suppression observed at 25% replacement. This threshold aligns with microstructural analyses showing RCBP’s Al3+ ions preferentially reacting with alkali hydroxides to form non-expansive gels, reducing pore solution pH and silica dissolution rates. Mechanical characterization reveals trade-offs between workability and strength development. Increasing RCBP substitution decreases mortar consistency and fluidity, which is more pronounced in RG-RCBS blends due to glass aggregates’ smooth texture. Compressively, both SS-RCBS and RG-RCBS mortars exhibit strength reduction with higher RCBP content, yet all specimens show accelerated compressive strength gain relative to flexural strength over curing time. Notably, 28-day water absorption increases with RCBP substitution, correlating with microstructural porosity modifications. These findings position recycled construction wastes and glass as valuable resources in circular economy frameworks, offering municipalities a pathway to meet recycled content mandates without sacrificing structural integrity. The study underscores the importance of waste synergy in advancing sustainable mortar technology, with implications for net-zero building practices and industrial waste valorization. Full article
(This article belongs to the Section Construction and Building Materials)
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26 pages, 2724 KiB  
Review
From Different Systems to a Single Common Model: A Review of Dynamical Systems Leading to Lorenz Equations
by Juan Carlos Chimal-Eguía, Florencio Guzmán-Aguilar, Víctor Manuel Silva-García, Héctor Báez-Medina and Manuel Alejandro Cardona-López
Axioms 2025, 14(6), 465; https://doi.org/10.3390/axioms14060465 - 13 Jun 2025
Viewed by 459
Abstract
This paper presents an analytical exploration of how diverse dynamical systems, arising from different scientific domains, can be reformulated (under specific approximations and assumptions) into a common set of equations formally equivalent to the Lorenz system originally derived to model atmospheric convection. Unlike [...] Read more.
This paper presents an analytical exploration of how diverse dynamical systems, arising from different scientific domains, can be reformulated (under specific approximations and assumptions) into a common set of equations formally equivalent to the Lorenz system originally derived to model atmospheric convection. Unlike previous studies that focus on analyzing or applying the Lorenz equations, our objective is to show how these equations emerge from distinct models, emphasizing the underlying structural and dynamical similarities. The mathematical steps involved in these reformulations are included. The systems examined include Lorenz’s original atmospheric convection model, the chaotic water wheel, the Maxwell–Bloch equations for lasers, mechanical gyrostat, solar dynamo model, mesoscale reaction dynamics, an interest rate economic model, and a socioeconomic control system. This work includes a discussion of the unifying features that lead to similar qualitative behaviors across seemingly unrelated systems. By highlighting the Lorenz system as a paradigmatic limit of a broad class of nonlinear models, we underscore its relevance as a unifying framework in the study of complex dynamics. Full article
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