Search Results (3,200)

The article presents a systematic and critical theoretical–methodological review and conceptual synthesis of the region as a fundamental analytical category and the central subject matter of regional geography. The primary objective of the study is to critically re-examine and conceptually redefine the region through an ontological and epistemological analysis of classical and contemporary geographical paradigms. The study is based on a qualitative interpretative methodology that combines analytical–synthetic, historical–genetic, comparative, critical, and conceptual approaches in order to examine the ontological and epistemological foundations of the region within classical and contemporary geographical thought. The region is conceptualized as a complex, multilayered, and dynamic socio-spatial entity whose ontological status has continuously evolved—from the essentialist notion of an objective spatial reality characteristic of classical geographic paradigms toward a relational and constructivist concept shaped by the interaction of social practices, political processes, and identity articulations within contemporary theoretical frameworks. Attention is also given to the epistemological foundations of regional knowledge, linking various modalities of the production and interpretation of scientific knowledge. Furthermore, the paper examines the roles of power, knowledge, identity, and institutionalization in the formation of regions, as well as the significance of centripetal and centrifugal forces in maintaining or destabilizing regional coherence. The research challenges traditional concepts of the region and proposes its redefinition in accordance with contemporary approaches that conceptualize it as an open, fluid, and context-dependent analytical framework. In conclusion, from the perspective of new regional geography, the region is interpreted as an emergent relational configuration whose understanding requires a broad interdisciplinary and critical approach. Full article

The fractional Whitham–Broer–Kaup model governs nonlinear wave propagation in memory-dependent media, including porous structures, viscoelastic fluids, and irregular seabeds, yet the full dynamical spectrum from quasi-periodicity to deterministic chaos, the role of stochastic forcing, and reliable identification from noisy data remains insufficiently explored, particularly how the fractional order $\beta$ influences these regimes. This study addresses these gaps through a comprehensive, multi-method dynamical analysis of a representative nonlinear oscillator embodying key FWBK features. Three-dimensional attractor visualizations, return maps, and surrogate data tests demonstrate a transition from quasi-periodic toroidal attractors to fully developed chaos via torus breakdown, confirming that observed complexity originates from deterministic nonlinearity. Poincaré sections reveal multistability and KAM-type structures, where coexisting attractors depend on initial conditions, while increasing noise progressively disrupts coherent dynamics. The OGY control method effectively stabilizes unstable periodic orbits across chaotic regimes with minimal perturbation, and Lyapunov analysis indicates that stochastic forcing attenuates chaos while enhancing dissipation. The Fokker–Planck framework shows that noise reshapes probability landscapes, driving transitions from unimodal to bimodal distributions. Comparative analysis of SINDy, JMAP and VBA highlights trade-offs in interpretability, computational efficiency, and uncertainty quantification, while an integrated Bayesian–PCE–Sobol approach quantifies parametric uncertainty and reveals time-dependent sensitivity variations. Additionally, the overlapping of soliton solutions extracted via the enhanced modified Sardar sub-equation method reveals structural relationships among soliton families and their stability under interaction. Soliton branches that maintain high overlap under noise correspond to stable regimes, while those losing coherence indicate the onset of chaos. Furthermore, while the reduced dynamics in $\eta$-space are independent of $\beta$, the fractional order controls spatial compression and temporal scaling in physical coordinates, directly influencing observable wave localization. These results imply that fractional effects can modify chaos transitions, support controllability through OGY, and influence noise–instability interactions depending on $\beta$. This framework provides a robust, transferable methodology for analyzing and controlling nonlinear oscillatory systems under deterministic and stochastic conditions, with direct applications to FWBK-based models in coastal engineering, fiber optics, and quantum interference systems. Full article

Conventional span-morphing wings are often constrained by structural complexity, heavy weight, and discontinuous aerodynamic surface. Although flexible honeycomb and lattice structures offer lightweight solutions, they usually require external loads to maintain the deformed configuration and often exhibit limited stability under large deformation. In this study, a span-morphing wing section based on multistable honeycomb structures is proposed. The multistable honeycomb acts as the core deformation–load-bearing module, enabling multistage reversible spanwise reconfiguration through the bistable transition of cosine curved beams and the support of honeycomb structures. An equivalent nonlinear force–displacement model is derived to describe the structural response. Finite element analysis and fluid–structure interaction analysis are conducted to evaluate its mechanical and aerodynamic performance, while prototype fabrication and bidirectional morphing experiments are performed to demonstrate its functional feasibility. The results show that the proposed wing section achieves prescribed multistage state transitions, effectively regulates lift through span variation, and maintains good structural strength under typical aerodynamic loads. These findings demonstrate the potential of multistable honeycomb structures for lightweight and stable span-morphing wing design. Full article

The acceleration and deceleration of high-speed gas flow within a pipeline, induced by the action of flow-restriction devices, frequently result in the emergence of unsteady flow phenomena. Consequently, the generated excitation forces provoke intense vibrations in the pipeline, thereby substantially elevating the operational risks of the pipeline system. To mitigate such risks, the pipeline is typically subjected to fixed constraints to reduce vibration. A pipeline designed to simulate unsteady airflow was developed for the purpose of validating the vibration attenuation effect. Within this context, the effects of binding and friction constraints were compared through fluid–structure interaction simulation, and their respective mechanisms of action were analyzed individually. The results demonstrate that the constraints, in conjunction with the original pipeline, will result in a higher first-order natural frequency, which constitutes one of the primary methods for mitigating resonance effects. Both friction constraints and binding constraints significantly elevate the first-order natural frequency of the pipeline system, with binding constraints demonstrating higher efficiency. This phenomenon is attributable to the arch-like bending deformation observed in such experimental pipelines during first-order resonance, as binding constraints effectively maximize the restriction on pipeline strain. Through a comparative analysis of the time-domain and frequency-domain results of outlet pipe 1 before and after constraint application, it was observed that the axial RMS value of the constrained pipe decreased by 21.8%, while the radial value diminished by 33%. This finding further substantiates that imposing binding constraints at the location of maximum strain can elevate the pipe’s natural frequency by reducing both strain and the effective length of the “beam”, thereby significantly alleviating pipe vibrations induced by unsteady flow. Full article

Background: Systemic autoimmune rheumatic diseases-associated interstitial lung disease (SARD-ILD) presents with varied disease courses, emphasizing the need for reliable predictors of progression. The prognostic utility of bronchoalveolar lavage (BAL) in SARD-ILD remains underexplored. The objective of this study was to evaluate the role of BAL fluid lymphocyte count in predicting disease progression in patients with SARD-ILD. Methods: This observational study included patients with SARD-ILD undergoing BAL as part of their diagnostic workup. Disease progression was defined as either Forced vital capacity (FVC) decrease >10%, two out of the following three criteria within two years: FVC decrease of 5–10%, worsening symptoms, increased fibrosis on imaging, or any of the following: escalation of treatment, Interstitial lung disease (ILD) exacerbation, lung transplantation, or disease-specific mortality. Logistic regression identified predictors of progression. Time-to-progression was assessed using Kaplan–Meier survival curves. The optimal BAL lymphocyte threshold for predicting progression was identified using the Youden Index and the Wilcoxon method. Results: We identified 89 patients, of whom 30 (33.7%) had progressive disease. Progressors had a significantly higher BAL lymphocyte count compared to non-progressors (31.6 ± 24.8% vs. 14.3 ± 16.5%, p < 0.001). BAL lymphocyte proportion was significantly and independently associated with disease progression (odds ratio, 1.05; 95% confidence interval 1.02–1.07; p < 0.01). A lymphocyte count above 9 percent was associated with a markedly increased risk of disease progression (odds ratio, 13.14; 95% confidence interval, 4.20–51.98; p < 0.01). Conclusions: BAL lymphocyte count was associated with a higher likelihood of progression in SARD-ILD. BAL assessment may help identify patients at increased risk of disease progression. However, these findings should be considered exploratory and require validation in larger prospective studies and across individual SARD-ILD subtypes. Full article

A novel wide-neck classifier (WNC) was designed to address the problem that thickeners cannot achieve classification prior to flocculation in a single unit. Using the computational fluid dynamics-discrete phase method and PIV experimental method, the reliability of the model was validated. We studied the motion characteristics of different particles within the novelty-designed WNC. The primary forces acting on coal slime particles in the composite force field were gravity, drag force, pressure gradient force, and virtual mass force. Drag force dominated the classification and sedimentation processes. In contrast, gravity, pressure gradient, and virtual mass forces promoted downward sedimentation but hindered upward overflow. The classification of slime particles in WNC was divided into initial classification after tangential feeding and centrifugal classification in a cone. Both simulation and experimental results demonstrate that, under consistent feed conditions, mineral density significantly affected the distribution of particles at the classification underflow and classification overflow. Among the three minerals, kaolinite has the highest classification effect, followed by quartz, while coal has the lowest classification effect. Full article

Exploitation of deep (>4000 m) tight geothermal reservoirs is constrained by low native permeability and premature thermal breakthrough, limiting sustainable heat recovery. Here, we investigate THM (thermo–hydro–mechanical) controls on fluid flow and heat transport during cold-water reinjection in deep tight sandstone reservoirs through an integrated framework linking two-dimensional mechanistic analysis with three-dimensional field-scale modeling. A two-dimensional thermo-poroelastic model reveals that strong thermal contrasts induced by cold-fluid injection cause contraction of the rock framework and transient pore-space dilation under confinement, producing short-term permeability enhancement. This process alters local flow capacity and redirects early cold-front migration, with persistent impacts on subsequent heat transport. Field-scale simulations further quantify the coupled effects of well spacing and reinjection temperature on thermal breakthrough, defined as a 1 °C decline in production-well temperature. Increased well spacing delays cold-front arrival and significantly retards breakthrough, whereas lower reinjection temperature enhances early heat extraction but accelerates convective transport, leading to earlier breakthrough. The combination of thermally enhanced permeability and intensified convection promotes preferential flow channels, increasing breakthrough risk. Balancing thermal-breakthrough delay against the heat-extraction driving force, the simulations delineate a favorable engineering window for the investigated conditions and clarify how cooling-sensitive permeability evolution affects preferential flow and reservoir-scale thermal response. Full article

We address the paradoxical transformation of a classical-mechanical particle motion when the space and time scales of observation pass below the uncertainty principle threshold. This is analyzed in the language of classical statistical mechanics, considering specifically many-particle systems inhomogeneous along one spatial direction. We employ the density functional formalism in its square-gradient form and find: (i) The macroscopic solution is analogous to the classical trajectory of a particle under a potential of force given by (minus) the free energy density. Whereas, (ii) fluctuations around the solution in (i) are equal to the quantum-mechanical wave functions of a particle under a potential given by the curvature of the free energy density. We illustrate this situation with three textbook examples: A particle in a box, the harmonic oscillator, and the hydrogen atom. We show that their time-independent Schrödinger equation wave functions describe, respectively, the fluctuations of a fluid interface, of critical point fluctuations, and of a confined ideal gas. At large scales, sharp probability distributions make fluctuations irrelevant; the vanishing of the first variation yields the macroscopically observable statistical-mechanical non-uniformity, equivalent to the classical particle trajectory. But at sufficiently small scales, with necessarily very few particles, distributions appear much wider, fluctuations dominate, and one obtains the Schrödinger equation (for the microscopic potential). Full article

Large-scale dense-phase carbon dioxide (CO₂) injection is an energy-intensive process in the carbon capture, utilization, and storage (CCUS) value chain. To address insufficient utilization of inlet pressure potential energy and sealing/friction losses of conventional reciprocating pumps under high-base-pressure dense-phase CO₂ transport conditions, this study develops a dense-phase CO₂-oriented structural optimization scheme for a hydraulically driven opposed-piston reciprocating pump based on force-coupling. A dynamic model was established to clarify the in situ recovery mechanism by which inlet pressure potential energy is converted into auxiliary thrust, enabling the drive load to shift from absolute pressure to net pressure difference. Simulation results show that under the rated 8 MPa inlet and 25 MPa discharge condition, the optimized opposed-piston configuration reduces peak driving oil pressure by 31.39% compared with the non-opposed reference configuration. Field reliability operation data show an average normalized specific energy consumption of 0.422 kWh/(MPa·m³) during the selected 24 h continuous operating period. The optimized configuration improves inlet-pressure utilization and reduces hydraulic power demand under high-base-pressure dense-phase CO₂ injection conditions, providing theoretical support and engineering reference for low-energy CCUS injection systems. Full article

Nanoemulsions are thermodynamically unstable but kinetically stable colloidal dispersion systems with droplet sizes ranging from 20 to 500 nm. With their high specific surface area, excellent optical properties, tunable rheology, and remarkable penetration ability, these systems demonstrate enormous potential in enhanced oil recovery (EOR). This paper systematically reviews the significant advances in nanoemulsion characterization techniques and oil displacement mechanisms. The nanoemulsion characterization techniques are examined, covering a comprehensive multi-scale characterization system from particle size and distribution analysis (e.g., dynamic light scattering, laser diffraction), micro-morphology and structure visualization (e.g., transmission electron microscopy, atomic force microscopy), and interface and surface property characterization (e.g., interfacial tension measurement, zeta potential analysis) to stability and rheology assessment, as well as chemical composition and structure analysis. Furthermore, core mechanisms of nanoemulsions in oil displacement processes are briefly summarized, revealing multiple synergistic enhancement mechanisms including ultra-low interfacial tension and oil film stripping, rock wettability alteration, emulsification and viscosity reduction, improved fluid flow and injection pressure reduction. Finally, prospects for the potential application of nanoemulsion oil displacement technology in the development of low-permeability, tight, and heavy oil reservoirs are described by analyzing the current challenges such as unclear structure–activity relationships, full-chain stability (including storage, transport, injection, and reservoir aging), and environmental safety, and future research directions are pointed out, including clarifying structure–activity relationships, smart responsive system development, artificial intelligence-assisted design, and pilot-scale validation. Clarifying the link between nanoemulsion characterization techniques and oil displacement mechanisms is of significant academic and engineering value for promoting the transition from empirical application to rational design of related technologies. Full article

Lithium-ion batteries used in electric vehicles (EVs) are highly sensitive to temperature variations, and excessive heat accumulation can adversely affect their performance, lifespan, and safety. Therefore, an effective battery thermal management system (BTMS) is essential for maintaining safe operating conditions. This study proposes a novel air-cooled BTMS incorporating circular vent holes in an acrylic enclosure to enhance airflow distribution and convective heat transfer around LiNiCoMnO₂ batteries. A computational fluid dynamics (CFD) model was developed to investigate the effects of discharge rate (1C–2C), inlet air velocity (1.0–3.0 m/s), and inlet air temperature (25–35 °C) on thermal behavior. The results indicate that the proposed BTMS effectively maintains battery temperatures below the critical limit of 40 °C. Optimal cooling performance was achieved at inlet air temperatures of 25–35 °C, 25–30 °C, and 25 °C for discharge rates of 1C, 1.5C, and 2C, respectively. The proposed design provides a simple, effective, and practical BTMS solution for EV applications. These findings confirm that the combination of forced air cooling and optimized vent design significantly improves thermal management performance. Full article

Glass fiber reinforced epoxy laminates (GFRP) are increasingly used in structural applications where combined mechanical and environmental loading is unavoidable, such as in the aerospace, naval, automotive, and petrochemical industries. This study investigates the influence of aggressive environments on the impact response and damage mechanisms of GFRP laminates. Specimens were immersed in acidic (hydrochloric and sulphuric) and alkaline solutions (sodium hydroxide), oil (automotive engine and automotive brake fluid), and cementitious solutions (cement and metakaolin mortars) for a determined period to simulate severe service conditions. Low-velocity impact tests were subsequently performed to evaluate the residual impact performance in terms of absorbed energy, maximum force, and damage extent. The results demonstrate that environmental exposure significantly alters impact behavior, mainly through matrix plasticization, fiber-matrix interface degradation, and microcrack development. For shorter immersion times (12–30 days), the solutions are not highly aggressive, as the decrease in elastic energy remains below 15%, with cementitious solutions showing the lowest reductions even for longer exposure periods. In contrast, longer immersion times in alkaline solution, DOT4 oil, and metakaolin mortar lead to more severe deterioration, with elastic energy reductions between 30% and 40%, the most aggressive condition being immersion in NaOH for 36 days, which caused a 37.4% decrease. Alkaline and automotive brake fluid oil environments induced the most severe degradation, leading to reduced impact resistance and increased damage propagation. Full article

The tower with an attached vent stack is a special arrangement in chemical tower structures. Flow-induced vibration of this configuration directly affects the safe operation and structural fatigue life of the equipment. This paper investigates the vortex-induced vibration (VIV) characteristics of a two-cylinder system consisting of a tower and its attached vent stack. Through fluid–structure interaction (FSI) simulations of two unequally sized cylinders in a bundled arrangement, the vibration responses under first and second-mode critical wind speeds with a flow direction of 0° are analyzed. The analysis examines lift and drag coefficients, vibration displacements, and wake flow evolution to reveal the vibration response pattern under multi-parameter coupling. When the lift forces obtained from FSI are applied in a static calculation, the static results for both the first and second-mode critical wind speeds are approximately 250% larger than the FSI results, indicating a significant discrepancy. Further analysis shows that in the FSI simulations, a notable phase difference exists between the fluid excitation and the structural response, causing the lift force to do negative work during part of the vibration cycle, thereby limiting the net energy input. Under the second-mode critical wind speed, the lift distribution along the tower height is significantly non-uniform. The conventional static calculation method neglects both the phase difference and the non-uniform lift distribution along the height, leading to overly conservative predictions. Full article

Orthodontic tooth movement (OTM) is a biologically driven process resulting from the mechanically induced remodeling of the periodontal ligament (PDL) and alveolar bone. A marked inter-individual variability exists in the rate of tooth movement, susceptibility to adverse outcomes such as external apical root resorption (EARR), and overall treatment response. This narrative review synthesizes current evidence on molecular, genetic, and epigenetic biomarkers that underline these differences. We summarize established local biomarkers derived from gingival crevicular fluid and saliva, including inflammatory cytokines, matrix metalloproteinases, and bone remodeling mediators reflecting OTM compression- and tension-side biology. Beyond fluid biomarkers, growing attention is given to genetic and epigenetic determinants of OTM. Specific gene mutations are associated with impaired or absent tooth movement, while multiple single-nucleotide polymorphisms have been linked to increased risk of EARR. Recent studies further demonstrate that orthodontic forces induce epigenetic remodeling in PDL cells, including DNA methylation changes in the gene promoters, histone modifications, and force-responsive non-coding RNAs such as miR-21 and miR-146a, which collectively regulate osteoclastogenesis, inflammation, and tissue adaptation. These findings indicate that OTM is governed by an integrated network combining mechanical stimuli with genetic predisposition and dynamic epigenetic regulation. Understanding these mechanisms provides a foundation for the development of biomarker-guided, patient-specific therapeutic strategies. Full article

This paper investigates the static stability of a thin plate with elastically restrained boundaries in an axial channel flow. The fluid forces, including two-sided wall effects, are derived using a method that combines the potential-flow equation, the method of images, and operator theory. By incorporating Chebyshev polynomials with the energy method, a fluid–structure coupling model with variable boundary stiffness is established. The critical dynamic pressure, instability modes, and pressure distributions are calculated for different channel parameters and torsional spring stiffnesses. The results show that reducing the channel height or moving the plate away from the channel centerline decreases the critical dynamic pressure. A reduction in the torsional spring stiffness also leads to a monotonic decrease in the critical pressure. The channel walls have a negligible effect on the relative reduction in critical pressure caused by boundary relaxation. In addition, trailing-edge relaxation has a stronger influence on the critical dynamic pressure than leading-edge relaxation, because the negative pressure near the relaxed leading edge does negative work and thus provides a stabilizing effect. Full article