Search Results (1,215)

Horsehair generated during seasonal coat shedding represents an underutilized biogenic by-product with potential for textile valorization. In this Communication, we present a first proof-of-concept investigation of the suitability of equine body hair as a raw material for nonwoven production. Hair samples collected during the spring shedding period (March–May) were analyzed for their morphology, fiber dimensions, elemental composition, lipid content, and processing behavior. Pretreatment methods included cleaning and washing, solvent-based degreasing using methyl tert-butyl ether (MTBE), and lipid extraction using supercritical CO₂. Fiber processing trials were conducted using manual and industrial nonwoven formation techniques, followed by mechanical consolidation through needle punching and hydroentanglement. While the results demonstrate that horsehair can be processed into nonwoven structures, pure horsehair webs showed limited fiber cohesion and surface fiber shedding. Blended nonwovens containing Lyocell and sheep wool as well as multilayer structures were therefore produced and showed improved handling and reduced fiber release. In addition, preliminary supercritical CO₂ extraction trials demonstrated the recovery of a substantial lipid-rich fraction, indicating the potential to combine extraction and subsequent fiber utilization within a preliminary cascade valorization strategy. Our study establishes the technical feasibility of this approach while identifying limitations requiring further investigation, particularly quantitative mechanical and functional characterization, optimization of fiber cohesion, chemical characterization of the recovered extract, and environmental and economic assessment. Full article

The longitudinal seismic response of a high-pier long-span stiff-skeleton arch bridge is spatially asymmetric because unequal pier heights, the fixed–movable bearing arrangement, and arch–pier interaction create nonuniform force transfer paths, even when the installed fluid viscous dampers (FVDs) obey a symmetric velocity-dependent law. This study evaluates that response redistribution and the mitigation achieved by longitudinal FVDs under near-fault motions. A three-dimensional SAP2000 model was established using elastic beam elements for the girder, arch ribs, cap beams, and piers, Plastic (Wen) links for spherical steel damping bearings, foundation springs for pile–soil interaction, and Maxwell-type FVD links. Thirty combinations of damping coefficient and velocity exponent were first screened under an El Centro record scaled to 0.64 g. The selected case (α = 0.3 and C = 2000 kN·${\left(s/m\right)}^{\alpha }$) was then evaluated by paired analyses of models with and without FVDs under 15 records grouped descriptively as short-, medium-, and long-period pulse-like motions and non-pulse motions. Across the paired record set, the mean record-wise reductions were 21.34% for bridge-wide maximum bearing displacement, 27.56% for P2 pier-top displacement, 9.73% for bridge-wide maximum pier-base shear force, and 12.62% for bridge-wide maximum pier-base bending moment. Mean arch rib reductions ranged from 10.00% for axial force to 25.00% for bending moment. Seven of the eight monitored response metrics decreased under all 15 records; arch rib axial force decreased under 14 records and was unchanged under 1. Local force increases nevertheless occurred at several arch-supported piers in the spatial El Centro comparison, demonstrating that global mitigation does not imply spatially symmetric or uniformly beneficial component response. Within the selected record set, the medium-period group produced the largest average demands for several response measures, but this is a sample-specific observation rather than a resonance inference. Removing the extracted velocity pulse component reduced most responses, although the nonlinear original-versus-residual comparison cannot be interpreted as an additive pulse contribution. The paired record set check supports the robustness of the selected FVD case for the investigated sample, but does not establish record-independent optimality. Full article

Passive tuned mass dampers (TMDs) can reduce chatter, but designing and fabricating an accurately tuned absorber remains challenging due to manufacturing constraints. This study proposes a Design of Experiments and Finite Element Analysis (DOE-FEA) based constrained design optimization framework for a passive two-degree-of-freedom (TDOF) TMD to suppress regenerative chatter in boring operations by considering practical and manufacturing constraints on absorber position, mass ratio, moment of inertia and fixed inter-spring distance. The proposed, additively manufactured TMD housing, made from polylactic acid (PLA), includes a mass block supported by two spring-damper elements that enable coupled translational and rotational interactions with the boring bar. A finite-element forced vibration analysis of the boring bar TMD system is developed to obtain the real and imaginary parts of the frequency response function (FRF), which are then used to construct the stability lobes. The minimum limiting depth of cut over the spindle speed range is used as the optimization criterion, and response surface methodology (RSM) is used to obtain optimum absorber parameters within realistic design constraints. The dynamic behaviour of the TDOF TMD is experimentally and numerically evaluated and compared with that of a single-degree-of-freedom (SDOF) TMD, attributing the relative improvement in performance primarily to the combined effects of independent absorber architecture, mass, stiffness and damping distribution and dynamic tuning. The results showed that the optimal TDOF TMD achieved a DOC of 11.054 mm, while the SDOF TMD achieved 4.335 mm. The experimental investigation of additively manufactured TDOF and SDOF TMDs demonstrated qualitatively similar dynamic phenomena to those of the corresponding numerically optimized absorbers. Time-domain acceleration response, spectrogram and power spectrum were used to compare these dynamic phenomena demonstrated by the SDOF and TDOF TMDs. A reduction in corresponding first and second amplitude peaks from −2.8 dB (670 Hz) and −22.7 dB (1360 Hz) in the case of the SDOF TMD to −17.6 dB (600 Hz) and −23.8 dB (1150 Hz) for the TDOF TMD verified the vibration attenuation and frequency redistribution phenomenon as exhibited by the FE-model. Full article

Cold recycled mixtures with bitumen emulsion (CRME) serving in seasonally frozen regions are susceptible to mechanical deterioration under repeated freeze-thaw (F-T) cycles, which is primarily manifested as interfacial damage and crack propagation. However, the micro-mechanical processes associated with the transmission and dissipation of frost-heaving stresses induced by water-ice phase transition within the interfacial transition zone (ITZ) between reclaimed asphalt pavement (RAP) and asphalt mortar remain to be further characterized. In this study, a numerical simulation approach coupling frost heave effects with the phase transition of water-ice particles was developed based on X-ray computed tomography (CT) and the discrete element method (DEM), and the micro-mechanical parameters of the RAP-asphalt mortar ITZ were determined through laboratory experiments. Combined with acoustic emission (AE) monitoring, the damage evolution characteristics of cold recycled mixtures and the associated interfacial damage mechanisms under freeze-thaw action were systematically investigated. The results indicate that the optimal micro-parameters of the RAP-asphalt mortar ITZ can be taken as approximately 85% of those of virgin asphalt mortar. After 20 freeze-thaw cycles, the number of shear cracks and tensile cracks in ITZ on RAP surface reached 493 and 92, respectively, which were much higher than 11 and five on the surface of new aggregate. ITZ was the main control weak area of freeze-thaw damage. Compared with the unfrozen specimens, the minimum effective contact number of mortar decreased by 1.63%, 4.52% and 8.52% respectively after 5, 10 and 20 freeze-thaw cycles, and the total effective contact number decreased from 75,842 to 69,383. Freeze-thaw cycles significantly reduce the strain energy storage capacity of CRME: the maximum energy storage capacity of the adhesive spring decreased from 2.15 J in the non-freeze-thaw state to 1.28 J in 10 cycles (a decrease of 40.47%) and 1.16 J in 20 cycles (a decrease of 46.05%), and the damage mode changed from brittle fracture to interface-controlled energy dissipation. The proposed water-ice phase transition-based DEM framework provides a reliable numerical tool for investigating freeze-thaw damage mechanisms and supporting durability-oriented design of cold recycled pavement materials. Full article

The tunnel portal section is one of the most seismically vulnerable parts of a tunnel, where strong earthquakes may trigger slope instability and induce plastic damage in the tunnel lining. Based on viscous-spring artificial boundary theory, a seismic oblique-incidence method applicable to tunnel portal sections is developed by incorporating the effects of slope topography. A three-dimensional finite element model is then established to investigate the seismic response and damage mechanisms of the tunnel portal section subjected to obliquely incident SV waves. The numerical calculation results in this study indicate that fully connected plastic deformation zones eventually develop in both the original slope site and the slope site with a tunnel structure, leading to slope instability characterized by downward sliding of the rock mass along a slip surface. However, in the presence of a tunnel structure, plastic deformation initiates simultaneously at the slope toe and near the tunnel portal. The maximum plastic strain is concentrated near the tunnel portal. Both topographic amplification and the accumulation of sliding debris markedly aggravate lining damage. The seismic-wave incidence angle, ground conditions and seismic-wave spectral characteristics all have pronounced effects on plastic deformation in both the slope site and tunnel lining at the tunnel portal section. In addition, tensile damage is more pronounced and extends over a wider area than compressive damage. At shear-wave velocities of 450–550 m/s in the upper soft-rock site, the damage zone is approximately two to three times the horizontal projection length of the slope, which is identified as the primary damage zone and should be regarded as a key seismic fortification area in tunnel design. Full article

Monolithic precast reinforced concrete (RC) frames with cast-in-place joint cores and grouted-sleeve splices are increasingly adopted in seismic regions, yet connection degradation is not carried through to system-level fragility: existing studies take hinge properties from code tables or one test, or stop at the joint. This study closes that gap with a reproducible transfer route in which the degrading, pinched M–θ hysteresis identified from a refined joint model becomes structure-level hinge parameters, with every intermediate quantity reported so that the route can be reproduced elsewhere. The joint model is an explicit finite-element interface-spring/contact strategy with Mohr–Coulomb interface behavior, tension cut-off, local spring failure, and sleeve–grout–rebar bond slip. Incremental dynamic analysis and fragility assessment of a six-story monolithic precast frame and a comparable cast-in-place frame show larger inter-story drift demands in the precast frame. At PGA = 0.40 g, its collapse exceedance probabilities are higher by 0.73 and 0.44 percentage points in X and Y, respectively. Global performance is broadly comparable, but the precast frame shows a consistent, modest unfavorable tendency caused by connection pinching and reduced ultimate rotation. Interface treatment, sleeve grouting quality, and connection-level ductility should therefore be explicitly considered in seismic performance assessment and design. Full article

This study addresses the inherently low damping and vibration susceptibility of carbon fiber reinforced polymer (CFRP) laminated cantilever plates by developing a comprehensive dynamic modeling and active vibration control framework. An electromechanical coupling model incorporating macro-fiber composite (MFC) actuators and sensors is established using the first-order shear deformation theory (FSDT) and the assumed mode method, with virtual springs introduced to account for non-ideal clamped boundary conditions. A reduced-order state-space model is then derived through model reduction, and a linear quadratic Gaussian (LQG) controller is designed for optimal state estimation and feedback control. The theoretical model is systematically validated via convergence analysis, ANSYS finite element simulations, and LMS impact hammer testing. The results demonstrate that, with the relative errors of the first four natural frequencies controlled within 2%, the theoretical mode shapes are highly consistent with those obtained from ANSYS simulations. An active vibration control experimental platform is established, and the effectiveness of the control strategy is verified under dual-spectrum harmonic and impact excitations. The results show that the designed LQG controller can effectively suppress multi-modal vibrations, substantially attenuating the response amplitudes of dominant modes and significantly accelerating the transient vibration convergence. This study addresses the challenge of precisely characterizing actual non-ideal clamped boundary conditions. Through model order reduction and closed-loop LQG control experiments, it provides a comprehensive set of theoretical methodologies, numerical solution strategies, and engineering-oriented experimental schemes for the electromechanical coupling dynamic modeling and optimal vibration suppression of CFRP thin-walled composite structures. Full article

Atmospheric deposition in industrial basins of Central Asia is strongly influenced by local emissions and wintertime dispersion conditions. This study characterized snowpack at 63 sampling stations across Ust-Kamenogorsk, Kazakhstan, including operational background station 1, on 24–26 February 2025 after a 116-day accumulation period. Major ions were determined in a spatially distributed exploratory subset of 16 samples, and trace elements were measured in samples from all 63 stations by means of inductively coupled plasma mass spectrometry and optical emission spectrometry. Mean meltwater pH and total dissolved solids were 6.55 ± 0.34 and 37.3 ± 18.0 mg L⁻¹, respectively. Charge-balance errors for the 16 hydrochemical samples ranged from −0.3% to +0.7%. Using the contamination index based on exceedances of the current Kazakhstan water-quality thresholds, 48 stations had CI < 1, seven had CI = 1–3, and eight had CI > 3; the highest value (60.21) occurred at station 26. Principal component analysis showed that the first three components explained 53.6% of the variance and separated a broad mineral/industrial aerosol association from a Pb–Cd–Zn association consistent with non-ferrous metallurgy and mixed urban sources. Cadmium was therefore interpreted as the principal contributor to the MPC-normalized index at the most affected stations, rather than as the dominant component by absolute concentration. The dissolved fraction can be mobilized during spring melt, indicating a potential pathway to soils and receiving waters, although direct ecological or human-health risk was not quantified. Station-level point mapping and projection along the NW–SE axis showed localized multi-element maxima rather than a monotonic citywide gradient. Full article

Betaine aldehyde dehydrogenase (BADH) catalyzes the final step in glycine betaine biosynthesis, but the evolutionary divergence and differential salt responsiveness of BADH homeologs in bread wheat remain unclear. We identified six TaBADH genes and analyzed their phylogenetic relationships, conserved motifs, gene structures, promoter cis-acting elements and synteny. RNA-seq and qRT-PCR were used to compare expression in salt-tolerant Jimai 60 and salt-sensitive Chinese Spring under 200 mM NaCl, and BADH activity, glycine betaine, H₂O₂ and malondialdehyde (MDA) were measured during treatment. The genes separated into chromosome group 2 and group 6 clades with distinct structural and transcriptional patterns. TaBADH-2B encoded a shorter protein and lacked several conserved motifs. Group 6 genes showed stronger salt-responsive expression in Jimai 60, with TaBADH-6D displaying the strongest and most sustained induction. Jimai 60 also showed higher BADH activity and glycine betaine accumulation and lower H₂O₂ and MDA contents at later time points. Expression of TaBADH-6D improved E. coli growth under 200 mM NaCl. These findings identify homeolog-specific divergence within the BADH wheat family and support TaBADH-6D as a candidate for plant-level functional validation. Full article

This paper presents the design, numerical analysis, and experimental investigation of a compact traveling-wave piezoelectric motor for continuous and incremental angular motion. The key advancement of the proposed design is a compact coaxial direct-drive architecture that combines a single ring-shaped piezoelectric stator with four independently excited electrode sections, three discrete spherical contact elements, a cone-shaped rotor, and an adjustable spring-based preload mechanism. In contrast to conventional traveling-wave motors employing continuous annular or toothed contact interfaces, the proposed configuration localizes the stator–rotor interaction at three predefined contact points while allowing both continuous bidirectional rotation and incremental angular positioning within the same actuator. Numerical analysis identified the operating mode at 39.95 kHz and confirmed the formation of elliptical displacement trajectories at the spherical contact elements. The calculated resonance frequency and effective electromechanical coupling coefficient were 39.93 kHz and 4.36%, respectively. Experimental measurements showed resonance of 39.94 kHz with an effective coupling coefficient of 4.47%. The motor achieved a maximum rotational speed of 87 ± 2.2 RPM at 180 V_p-p. The maximum stall torque reached approximately 8.3 N·mm and 8.4 N·mm for clockwise (CW) and counterclockwise (CCW), respectively, at 180 V_p-p. Depending on the excitation amplitude, the angular step varied from 0.082 ± 0.015° to 3.038 ± 0.120°. The results confirm that the proposed compact motor can provide controllable continuous rotation and incremental angular positioning. Full article

Torque-limiting mechanisms are safety-critical elements in mechanical, automotive, robotic, aerospace and medical systems, where controlled torque transmission is required to avoid overload failure. However, the influence of dent–slot geometry on torque stability, variability and tolerance sensitivity remains insufficiently quantified. This study examines the effects of dent height, dent angle and spring plate thickness on the torque response of a compact elastic, shape-dependent torque-limiting mechanism. An integrated methodology comprising conceptual design, mathematical modelling, theoretical analysis, finite element analysis, manufacturability assessment, material characterisation, dynamic testing and VIKOR-based decision-making was implemented. Five feasible spring-drive plate configurations were investigated using two dent heights, two dent angles and two spring plate thicknesses. Material and interface properties for the Ck67–SINT D39 tribological pair were determined through tensile, flexural and friction tests, while dynamic torque and output-force data were obtained using a dedicated test bench and statistically evaluated after Chauvenet-based removal of isolated peak values. The mathematical, theoretical, numerical and experimental results showed close agreement, with torque deviations below approximately 1.5% for the main comparison metrics. Increasing dent height from 1.40 to 1.80 mm reduced relative torque variability by 34.6%, whereas reducing the dent angle from 110° to 90° increased relative torque variability by 95.0%. Configuration A2 provided the best balance, confirming dent geometry as a controllable design variable. Full article

Skeletal-anchored mesial sliders are increasingly used for molar mesialization, yet their mechanical behavior has not been compared under standardized conditions. This in vitro pilot study evaluated four slider designs (BENEfit^® Beneslider [BB], TADMAN Beneslider [TB], IZE Slider [IO; OrthoLIZE GmbH], Slider on Minipin [SO; OrthoLIZE GmbH]), each combined with elastic chains (-C) or NiTi springs (-S), to characterize force loss, mesial movement, and associated mechanical side effects using an experimental biomechanical measurement system. Using repeated measurements on one specimen with 1 N of applied force, three-dimensional tooth movements were recorded across 200 simulation steps per run. The sliders showed design-dependent mechanical patterns: IO sliders produced the smallest sagittal movements (IO-C: −0.84 mm [0.05], IO-S: −0.79 mm [0.02]) and the highest force loss (IO-C: 88.1% [2.1], IO-S: 89.8% [0.3]), whereas BB-S and TB-S generated larger mesialization distances (BB-S: −3.55 mm [0.53], TB-S: −3.46 mm [0.08]) with lower force loss (BB-S: 42.8% [9.2], TB-S: 21.1% [2.9]). Translational deviations remained small, while rotational effects were more pronounced. These findings represent mechanical tendencies of the tested configurations under idealized conditions and do not account for biological variability, periodontal compliance, or patient-specific factors. As such, the results cannot be generalized to clinical performance but provide preliminary reference data. Expanded investigations using multiple specimens, biological modeling, or finite element analysis will be necessary to determine how these mechanical patterns translate into clinical tooth movement. Full article

To reduce the modeling effort and computational cost of assembled composite shear walls with C-shaped steel frames in global structural analysis, this study proposes an engineering-oriented simplified mechanical analysis method. Three representative specimens—a C-shaped steel-frame composite shear wall (CSCSW), a rectangular steel-frame composite shear wall (RSCSW), and a T-shaped, C-shaped steel-frame composite shear wall with a vertical connection (VTCSWC)—are decomposed into functional modules according to their load-transfer mechanisms. Simplified models comprising axial springs, diagonal braces, and a modified three-vertical-line-element model are established. Degrading bilinear Clough and trilinear Takeda models are adopted as the restoring-force relationships, and the governing parameters are determined through mechanical equilibrium analyses. The three simplified wall models are implemented in OpenSees to obtain hysteresis curves, skeleton curves, and stiffness-degradation responses. Comparisons with quasi-static test results show that the errors in peak load and secant stiffness are both within 10%, while the models reproduce the stiffness degradation and pinching characteristics of the specimens. Relative to refined three-dimensional solid finite element models, the proposed approach substantially reduces computational cost without compromising engineering accuracy, providing an efficient tool for structural design and seismic performance assessment of assembled C-shaped steel-framed composite shear-wall systems. Full article

A unified modeling framework is presented in this work to predict the free vibration and loss factor characteristics of damping sandwich rotational plates. The formulation starts from the first-order shear deformation theory, where the zigzag hypothesis and interlayer displacement continuity are combined to couple the displacement fields of the individual plies. An artificial spring scheme is adopted to enforce the layer–layer compatibility and the external boundary restraints, which leads to a Lagrangian functional composed of the kinetic energy, the strain energy, and the potential energies contributed by the boundary and coupling springs. The displacement unknowns are discretized with Chebyshev polynomials of the first kind, and the natural frequencies and damping loss factors are extracted by solving the resulting eigenvalue problem with the Rayleigh–Ritz method. Convergence tests are conducted, and the reliability of the model is validated against finite element results. Finally, a series of numerical examples is presented to systematically investigate the effects of key model parameters on the vibration characteristics of the structure. The results indicate that increasing the thicknesses of the inner and outer layers of the damping sandwich rotational plate structure can significantly raise the natural frequencies. Increasing the inner diameter helps to reduce the area of the low-frequency region, where the difference between the two sides exceeds 40 Hz, caused by the close thicknesses of the inner and outer layers. When only the outer boundary is clamped, the natural frequencies of the annular plate are more than twice those of the solid rotational plate, although the solid rotational plate yields a larger loss factor. When only the outer circular edge is fixed, increasing the total thickness of the structure can effectively raise the natural frequencies, with a maximum increase exceeding 110 Hz, while the loss factor decreases significantly. Full article

This research introduces an analytical model based on a semi-rigid nodal bar system. In this model, carbon–carbon covalent bonds are represented as beam elements, while carbon atoms are treated as semi-rigid nodes connecting these elements. A spring coefficient is incorporated to quantify nodal stiffness. Building upon this construct, spatial stiffness equations for the semi-rigid beam elements are derived, enabling a systematic exploration of how boundary conditions and dimensional factors influence the Young’s modulus and buckling stress in both pristine and defect-laden graphene. The findings reveal that defect-free graphene exhibits remarkable dimensional stability, with its Young’s modulus consistently approximating 1.0 TPa and fluctuating within ±2%. Upon the introduction of defects, the material’s stiffness diminishes significantly, with a maximum reduction of 19% observed when the density of defective elements surpasses a critical threshold. Moreover, the relationship between boundary conditions and buckling stress aligns closely with classical thin plate theory. Under identical dimensional constraints, the buckling stress ratios for fully fixed, fixed-simple, simply supported, and cantilevered boundaries conform to the theoretical ratio of 16:8:4:1. Full article