Search Results (2,929)

Regenerative vibrations are a major hindrance to flexible cantilever structures during milling, resulting in a reduced tool life and diminished surface finish. In this research, two actively controlled methods are directly compared: a genetic algorithm (GA)-optimized classical proportional-integral-derivative (PID) controller and a GA-optimized fractional-order PID (FOPID) controller for a milling-dependent regenerative force on a flexible cantilever beam via numerical modeling, using piezoelectric actuator/sensor patches. The original aspect lies in synergistically combining fractional-order control with genetic algorithm-based optimization to actively reduce chatter and increase the machining stability of flexible milling systems. The simulation results from the GA-FOPID controller exhibited a reduction in vibration of approximately 92.70% compared with the open-loop system by reducing the RMS value from 1.5058 × 10⁻⁴ m to 1.0996 × 10⁻⁵ m. By reducing the vibration level and enlarging the predicted stable machining region, these improvements could potentially contribute to longer tool life, improved surface finish, and reduced post-processing requirements, although these technological benefits were not directly modeled in the present study. The main innovation of this work involves a unique combination of fractional-order control, PZT actuation, and genetic algorithm optimization in a regenerative milling delay architecture. To the best of the authors’ knowledge, based on the literature surveyed in this work, this combination of techniques has not previously been reported for active chatter suppression. The stability lobe diagram (SLD) analysis, conducted under the single-mode approximation that serves as the reference framework for the like-for-like comparison of the five investigated configurations, shows that the critical axial depth of cut at the representative spindle speed increases from a_p,crit(1500) = 0.061 mm for the uncontrolled system to 0.52 mm under GA-FOPID control. This enlargement of the predicted stable machining region was further confirmed, at a comparable order of magnitude, when the structural model was extended to include the two next bending modes, indicating that the trend is not an artifact of the single-mode simplification. Therefore, although the results were obtained exclusively from numerical simulation and have not yet been experimentally validated, they support the use of optimization-based methods to implement FOPID strategies as a means to increase both reliability and performance of flexible milling configurations. Full article

Waste cooking oil (WCO) was investigated as a waste-derived reactive precursor for a cured organic binder in highly mineral-filled composites containing turmeric. Ten formulations selected from a broader experimental screening were prepared from WCO, sulfuric acid, quartz sand, and turmeric added at 1–7% relative to the dry mass of quartz sand. Formulation-specific thermal curing was conducted at 190–210 °C for 12–20 h. Because the binder content, acid-to-binder ratio, turmeric content, curing temperature, and curing time varied simultaneously, the study was designed as an exploratory multifactorial screening rather than as a controlled assessment of individual processing variables. FTIR, ¹H NMR analysis of acetone-soluble constituents, TGA, and SEM-EDS were combined with mechanical screening, water-absorption, contact-angle, and microbiological measurements. Bending and splitting tensile strengths ranged from 1.15 to 2.42 MPa and from 0.30 to 0.52 MPa, respectively. Water absorption ranged from approximately 4.8% to 9.0%, while water contact angles exceeded 90° for all investigated formulations. Selected formulations reduced the surviving fraction by more than 90% for Staphylococcus epidermidis and by approximately 70% for Pseudomonas aeruginosa under the applied suspension-assay conditions. The estimated C₅₀ values of 60.6–83.3 mg mL⁻¹ indicated measurable concentration-dependent responses at relatively high nominal composite concentrations. The available results support curing-associated transformation and consolidation of the WCO-derived binder phase but do not quantify crosslink density or retained organic content. Because no matched turmeric-free composite or surface/eluate pH measurements were available, the biological effects are attributed to the complete composite formulations rather than specifically to turmeric or intact curcumin. The results provide an exploratory basis for the further development of waste-derived, non-load-bearing polymer–mineral composites with functional surface and biological properties. Full article

The fatigue performance of gears is very important to the safe operation of the transmission system. For gears fabricated using novel materials and advanced manufacturing processes, fatigue limit testing entails significant costs and prolonged timeframes, thereby constraining the rate of design iteration. In this paper, a rapid prediction method for the bending fatigue limit of gears is proposed. This method starts with the S-N curve of the material. Based on the rapid test theory and the principle of small sample statistics, combined with the step-down loading method, the safety fatigue limit of the gear under certain reliability is estimated. Compared with the up-and-down method, the error of this method is within 7.8%, verifying the feasibility of this data processing. At the same time, in this paper, the bending fatigue test of corrosion-resistant nitrided steel gears is carried out, and the bending fatigue limit of corrosion-resistant nitrided steel gears under 99% reliability is quickly obtained. This method holds significant engineering significance in saving test costs, reducing the number of tests, and shortening the development cycle. However, it is currently only applicable to standard spur gears and does not yet consider factors such as the geometric characteristics of helical gears and the corrosion resistance of materials. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

Under out-of-plane loading, composite sandwich wall panels may develop relative slip between the wythes and end slip at the intermediate-layer interface, weakening composite action and flexural stiffness. Previous studies have mainly focused on bearing capacity and connector performance, while the complete slip-development process, parameter effects, and quantitative slip-warning indicators remain insufficiently investigated. To investigate the flexural slip mechanism and design control method, three one-way composite sandwich wall panels with different wythe thicknesses, reinforcements, and stiffness ratios were tested under four-point bending. The load–deflection response, crack development, relative slip, and end slip were recorded. The measured slip values were normalized by the midspan yield deflection to obtain the absolute slip ratio, relative slip ratio, and end slip ratio. The results show that both the relative slip between the inner and outer wythes and the end slip exhibit a three-stage evolution with increasing load: almost no slip before cracking, approximately linear development after cracking, and rapid increase after yielding. The stiffness matching of the inner and outer wythes and the thickness of the intermediate layer are important factors affecting slip development. Based on the test results and comparison with existing experimental data, the yielding stage is recommended as the slip-warning control point, with warning values of 0.03 for the relative slip ratio and 0.06 for the end slip ratio. Finally, a simplified model based on partial composite action theory was established using binary linear regression and the least-squares method. The model achieved a centered $R^2$ of 0.937, while the slip influence coefficient increased from 2.4–8.8% at yielding to 30.3–66.0% at the peak stage, quantitatively supporting yielding-stage warning control. Full article

Background: With the growing popularity of golf, the wood consumption and white pollution caused by traditional wooden and plastic golf tees create an urgent need for green, degradable, high-performance alternatives. Materials and Methods: To address this, a novel approach for the green fabrication of high-performance composites was developed utilizing a single agricultural solid waste (chestnut shells) bridged by an extremely low proportion (4 wt%) of a thermoplastic agent (polylactic acid, PLA). A mild dilute hydrochloric acid hydrothermal pretreatment selectively removed hemicellulose to expose active hydroxyl groups, followed by a wet hot-pressing process optimized at 80 °C, 4 h, 15 MPa, and 180 mesh. Results: Under these conditions, the resulting CS-APLA composite tees exhibited a bending strength of 86.32 ± 6.46 MPa and a dynamic impact toughness of 104.89 ± 5.26 kJ/m², representing significant increases of 64.86% and 41.69%, respectively, compared to the pure biomass material, and outperforming conventional commercial wooden tees. A 75-day soil burial test demonstrated a weight loss of approximately 45.42%, confirming a balanced degradation rate. Conclusions: Multi-scale characterization confirmed that the synergistic reinforcement relies objectively on an acid-treatment-induced hydrogen-bonding network coupled with in situ polymer-bridged microdomains formed by PLA flow filling during hot-pressing. This study provides a sustainable route for the high-value utilization of agricultural solid waste. Full article

The use of manufactured sand (MS) as a substitute for natural sand or quartz sand in the production of ultra-high-performance manufactured sand concrete (UHPMC) represents a critical approach to alleviating the shortage of high-quality aggregates and promoting low-carbon development. However, after steel fibers and steel rebars are introduced into this material system, the synergistic working mechanism and damage evolution characteristics of the resulting ultra-high-performance manufactured sand-reinforced concrete (UHPMRC) beams under flexural loading remain largely unexplored. Acoustic emission (AE) technology, owing to its high sensitivity to the initiation and propagation of microcracks, enables real-time dynamic monitoring of UHPMRC beams throughout the entire process from the elastic stage to fracture failure, thereby providing an effective means to reveal the internal performance degradation law. Accordingly, this study conducted simultaneous AE monitoring on small-scale reinforced beams under four-point bending and investigated the effects of MS replacement ratios (0%, 50%, 100%) and steel fiber contents (1.0%, 1.5%, 2.0%). Results show that UHPMRC beams with 100% MS replacement and 1.5% steel fiber content achieve optimal performance. Compared to 0% MS specimens, those with 100% MS exhibit superior early stiffness, ductility, and flexural capacity due to the combined effects of steel fibers and MS. Beams with 2% steel fiber content experienced fiber clustering, reducing bridging capability and promoting earlier cracking relative to those with 1.5% fibers. AE energy parameters accurately identified cracking and characterized crack propagation in UHPMRC beams. Increasing MS content raised the proportion of shear cracks while reducing tensile cracks. The highest shear signal proportion occurred at 1.0% steel fiber content. These findings provide a valuable reference for the design of sustainable high-performance reinforced-concrete structures using manufactured sand. Full article

This paper presents a methodology to evaluate the entire process of thermal evolution and fracture failure within stay cables subjected to sheath fires. Computer software FDS 2021 and ABAQUS 2021 are applied to build a sequentially thermos–mechanics coupled method integrating thermal, structural, and fracture dynamic analyses in stay cables under sheath fire exposure conditions. Herein, three representative fire scenarios including full-circumferential, top-side, and bottom-side ignition are reconstructed. Further, 127 individual wires, accounting for interstitial cavity radiation and contact heat transfer, are utilized to perform analysis on sectional temperature in stay cables. The results indicate that the ignition mode dictates the cross-sectional temperature gradient, with localized ignitions inducing highly asymmetric thermal fields and pronounced internal bending moments. Elevated temperatures trigger a progressive load redistribution from the degraded fire-facing wires to cooler internal layers. Ultimately, abrupt global fracture occurs when the residual ultimate load-carrying capacity intersects with the actual applied tension, resulting in a fracture morphology that closely corresponds to the spatial thermal distribution. Furthermore, the structural capacity degradation exhibits three distinct time-dependent stages: a slow degradation stage, a sharp decline stage, and a recovery stage. Among the analyzed scenarios, full-circumferential ignition induces the most drastic overall capacity reduction, while bottom-side ignition poses a markedly greater rupture risk than top-side ignition. Full article

Towed hydrophone arrays are widely employed for underwater target detection and direction-of-arrival (DOA) estimation. However, array shape distortion induced by ocean currents, internal waves, and platform maneuvers severely degrades beamforming performance and DOA estimation accuracy. In this paper, a novel Bayesian fusion framework is proposed to achieve robust array shape estimation. Specifically, based on the time-delay estimates derived from the phase differences of line-spectrum components in a pre-processing step, the array geometry is first reconstructed via a piecewise straight-line fitting method. Concurrently, an existing hidden Markov model (HMM)-based method is adopted to estimate the inter-segment deviation angles, in which the smoothness of the array shape is enforced through the state-transition probabilities. The proposed framework then treats these two preliminary estimates as observations from distinct sources and incorporates a smoothness prior within a maximum a posteriori (MAP) formulation that admits a non-iterative closed-form solution to enforce physical continuity constraints on the array geometry. By fusing these complementary estimates, the proposed method simultaneously preserves local sensitivity to fine-scale bends and maintains global consistency of the array shape. Both simulation and lake-trial experiments validate the effectiveness of the proposed method, reducing the array shape estimation error by more than 30% relative to representative existing methods. Moreover, by relying solely on the received acoustic data, the method lowers the dependence on auxiliary sensors and the associated system cost. Full article

The layer-wise deposition process of three-dimensional concrete printing (3DPC) induces anisotropic behaviour, while cementitious materials exhibit pronounced tension–compression strength asymmetry. This study develops a concurrent topology and printing-direction optimisation framework for plain 3DPC under Drucker–Prager (D–P) strength constraints. Within a solid isotropic material with penalisation (SIMP) formulation, material density and printing orientation are updated simultaneously using the Method of Moving Asymptotes (MMA). A double-angle vector-field mapping regularises the π-periodic orientation field, while element-wise D–P failure indices are aggregated into a differentiable global constraint through P-norm aggregation with adaptive scale correction. Numerical studies on a four-corner pinned plate, a T-shaped bracket and a perforated deep beam show that the strength constraint reshapes load paths, suppresses local strength violations and increases ultimate load capacity by approximately 200%, 176% and 42%, respectively, relative to compliance-based optimisation. The optimised deep-beam layouts are reconstructed, converted into continuous printing paths, fabricated and tested under three-point bending. Experimentally, the mean ultimate load increases from 8.13 to 9.54 kN, corresponding to an increase of 17.39%, while the mean displacement at peak load and pre-peak energy are 20.58% and 41.16% higher, respectively. The experimental and finite element comparisons show closely similar ultimate-load increases of 17.39% and 17.43%, respectively. The framework provides a strength-aware route from concurrent numerical optimisation to the fabrication and structural assessment of plain 3DPC components. Full article

Glued laminated timber (glulam) is a high-performance structural wood product. However, means are still being researched to increase efficiency in challenges with a large scale of complexity, either owing to the diversity of the lamella’s material properties or through the development of computational models to better represent the real behavior of the material. This study aimed to determine a more efficient combined glulam beam in terms of the lamella’s proportion. The beams with a 12,000 mm span and a 150 × 600 mm cross-section were modeled using solid finite elements and a linear-elastic isotropic model. Two homogeneous and four combined glulam cross-sectional compositions were established based on the physical and mechanical properties of two strength classes (35 and 50 MPa), and their deflections and bending stresses were evaluated. Compared with that of homogeneous glulam beams with lamellae of the strength class 35 MPa, for softwood and hardwood lamellas, the combined cross-section with 33.3% of the lamellas of class strength 50 MPa, the load corresponding to the deflection limit increased by 17% and 12.4%, respectively. This composition had a higher self-weight only in relation to homogeneous glulam. It can be concluded that the combined glulam with a proportion of 33.3% was more efficient, considering the behavior of the beam under a load corresponding to the deflection limit, and that the lower self-weight affects the production and transportation processes. Full article

It has become taboo for a parent today to say “no” to a child. Children grow in this “supposed” freedom and child rights, and then some assume an attitude of always having their own way, a character devoid of “home wisdom”, also called “common sense”. It is only their way that matters; others must bow to them. They become arrogant, proud, selfish, insensitive, irresponsible, and lack initiative; simply put, they mold themselves into “beasts”. It is only when this beast of a child turns on their parents that they realize something went wrong and needs to be corrected, which is often too late. This adage has already applied: “it is easier to bend a tender tree than an old one”. In this sacred text, Luke 15:11–32, a father displayed an attitude, which causes the mind to inquire why he consented. Why did the father allow the son to have his way, knowing quite well that the son’s reasoning was wrong? Unfortunately, this is becoming the norm of the day. In the text, the son returned, but today, many children are so consumed in pride, self-righteousness, and arrogance that even when confronted, they will not agree that they are wrong. Others, who realize their abject situation, fail to make amends for fear of being laughed at, which is pride, and they perish in the process. This paper uses narrative criticism within the context of African biblical hermeneutics to explore the reason behind the father’s attitude and the wisdom behind the son’s final acceptance of his situation that motivates him to return. These reasons, this paper hopes, will help serve as a remedy. Full article

Structural irregularities can alter seismic deformation and internal force requirements, but comparisons of different types of irregularities using a single set of response measures remain limited. This research introduces a response-index framework for comparing seismic performance of irregular reinforced concrete (RC) buildings. Nine ten-storey RC models, one regular reference and eight with irregularities such as mass, re-entrant corners, vertical stiffness, and geometric irregularities, were evaluated through Response Spectrum Analysis. Six response parameters—roof displacement, maximum storey drift, drift ratio, base shear, column axial force, and column bending moment—were assessed using the Irregularity Amplification Factor (IAF), Normalized Response Index (NRI), Deformation–Force indices (DI–FI), and Irregularity Severity Score (ISS). The framework integrates response amplification, normalization, behavioral classification, and overall ranking within a unified reference-based process. The vertical stiffness model S-2 achieved the highest ISS (1.461), primarily due to a bending moment of 404.57 kip-ft, followed by S-1 (ISS = 1.285). Sensitivity analysis showed that S-2 consistently remained the top-ranked option, except when the bending moment was excluded. The framework provides a concise basis for identifying dominant response mechanisms and comparing the rankings of irregular configurations, thereby aiding seismic assessment and informing design decisions for RC buildings. Full article

In the manufacturing of carbon fiber/epoxy composites, different stacking sequences have different effects on the void inside materials. In this paper, the double-vacuum-bag (DVB) process was utilized to fabricate laminates with different stacking sequences, including different angles, different thicknesses and plain weave prepregs, and the single-vacuum-bag (SVB) process was set as the control group. The void content of different laminates in the cross-section was counted by image analysis software, and material thickness, density, and fiber volume fraction were measured by experiments. Three-point bending and short-beam-shear tests were conducted to evaluate the material mechanical properties. The results show that the void contents of laminates prepared by the DVB process are all less than 1% with different stacking sequences, while the laminates manufactured by the SVB process contain a large number of voids inside. The density and fiber volume fraction of the DVB process are higher than those of the SVB process. In terms of mechanical properties, the flexural strength and interlayer-shear-strength (ILSS) of the DVB process are higher than those of the SVB process. The results of this paper expand the application of the DVB process and provide a reference for low-cost manufacturing of composite materials. Full article

Digital modeling of traditional Chinese musical instruments significantly lags behind that of their Western counterparts, limiting advances in cultural preservation and related research. This paper addresses score-to-audio generation for the Chinese bamboo flute (dizi), aiming to synthesize expressive audio with human-like performance nuances directly from Musical Instrument Digital Interface (MIDI) scores. Two core challenges remain in existing score-to-audio synthesis methods: first, the scarcity of large-scale paired MIDI-audio training data for traditional Chinese instruments; second, the inability of standard MIDI to encode instrument-specific expressive techniques, such as vibrato, pitch bends, and ornamentations. To address these challenges, we propose a scalable workflow that generates large-scale synthetic MIDI-audio pairs through rule-based score randomization, automated digital audio workstation (DAW) rendering with commercial sample libraries, and standardized feature extraction. Performance technique information is directly encoded into the MIDI stream using out-of-range MIDI note numbers, achieving more effective conditioning than external control methods. Our system is built upon the Musical Instrument Digital Interface–Differentiable Digital Signal Processing (MIDI-DDSP) framework. Large-scale synthetic data is used for pre-training to establish timbral consistency, while real recordings from the University of Rochester Multi-Modal Music Performance (URMP) flute corpus are employed for fine adjustment to achieve expressive dynamic variations. Synthetic data alone yields stable but less expressive outputs, whereas real data alone risks overfitting. The combined strategy achieves a realistic timbre with controllable dynamics and performance techniques. Full article