Abstract: Cracks in planetary gearbox casings generate vibration responses, which, when properly isolated and analyzed, can be used for monitoring structural degradations. This paper provides a signal processing framework to effectively track casing crack related features in planetary gearboxes using carrier synchronous signal average (C-SSA). The proposed algorithm is based on processing the hunting-tooth synchronous signal average (H-SSA) to extract the C-SSA which contains the cyclic interaction between the gear loadings and the corresponding casing response. The root mean square (RMS) of the C-SSA signal can then serve as a health condition indicator (CI) to track crack propagation. Further enhancement can be achieved by applying the Hilbert transform (HT) on the C-SSA using the full bandwidth to derive squared envelope signal, which clearly shows the modulations from the crack response and further enhances the trending capability. To remove cyclic temperature influences observed in the trends, singular spectrum analysis technique (SSAT) has been used, ensuring the trend reflects the changes purely due to the damage progression. Experiments using three casing-mounted sensors show good capability to track crack progression. Tests under 100%, 125%, and 150% load levels show consistent performance across these operating conditions, with better results seen at higher loads. The results demonstrate that C-SSA and its squared envelope signal effectively enhances the sensitivity and reliability of vibration-based crack detection, providing a practical tool for long-term structural health monitoring of planetary gearbox.

Abstract: Addressing the issue of high cleaning loss rates in practical operations, this study designed adevice for detecting cleaning losses. Three-dimensional models of wheat kernels were constructed using Blender software. Subsequently, the discrete element method software EDEM was employed to simulate the impact process of wheat kernels and straw dropped from varying heights onto a sensing plate, obtaining the contact force history and particle trajectories. The results revealed a significant difference in the impact force between the two material types on the sensing plate, enabling material identification and loss rate calculation through signal acquisition.Based on this, a detection device comprising mechanical structures and a control system was designed. An ESP32 microcontroller was used to read data from a piezoelectric ceramic vibration sensor. After processing with a Kalman filter, material classification thresholds were determined based on the normal distribution pattern of the signals. Experimental parameters were initially identified through a three-factor, three-level experiment and subsequently optimized using response surface methodology. The experimental results indicated that the threshold discriminability and loss rate calculation accuracy were optimal when the sensing plate was installed at a height of 550mm with a tilt angle of 40°, and the conveyor belt speed was 8 meters per minute.Bench test verification demonstrated that the device achieved an overall error of less than 3%, with recognition rates for both wheat kernels and straw exceeding 97%.

Abstract: Volume fraction, or one-point statistics, is commonly used to homogenize composites. However, it contains no geometric information regarding the spatial distribution of the phases. The spatial distribution can be characterized using higher-order statistics. Two-point statistics (f₂) quantify average relative phase positions, and the geometric features encoded in f₂ influence material properties. However, just as a single volume fraction can describe multiple unique microstructures, some f₂ map to multiple distinct microstructures. The existence of multiple microstructures possessing the same f₂ is termed ‘degeneracy’ and is problematic for microstructure-sensitive design because unique microstructures may map to the same f₂ yet exhibit different properties. This study quantifies how pervasive degeneracy is in f₂ through exhaustive enumeration of all 2³⁶ ≈ 6.9¹⁰ possible 6 × 6 binary microstructures, and tests other metrics as ways to uniquely characterize microstructures with degenerate f₂. We determined that using nondirectional f₂ (i.e., orientation-averaged f₂) substantially increases degeneracy, nearly doubling the probability that a randomly selected microstructure will share the same f₂ as some other symmetry-inequivalent microstructure. Notably, the fraction of nontrivially degenerate microstructures does not increase monotonically with system size—a counterintuitive finding that challenges prior theoretical predictions. Finally, for the small microstructures examined, we determined that three-point statistics will fully resolve the degeneracy at a computational cost that scales as n⁴ (where n is side length), while two-point cluster functions resolve the majority of degeneracies with substantially lower computational overhead.

Abstract: In the grinding of silicon carbide, surface and subsurface damage have a significant im-pact on the product's surface quality. A method to obtain controllable crack dimension through laser irradiation on SiC surface and its effect on the grinding process was ana-lyzed. A series of experiments were carried out based on the orthogonal experimental de-sign, with systematic adjustments made to laser parameters including pulse energy (cur-rent), laser spot spacing, scanning times as well as grinding process parameters. During the experiments, the grinding force was monitored by a dynamometer, and the specific grinding energy was calculated accordingly. Pulsed engraving laser modification could effectively reduce the hardness of the ceramic surface layer by about 20%. The median and radial crack sizes in the subsurface layer induced by laser were in the range of 20.4 μm to 54.3 μm, which could effectively inhibit the further propagation of median and radial cracks during grinding, and simultaneously reduce the tangential grinding force Ft by about 30%. These conclusions were obtained by corresponding experiments, which link the surface roughness with laser power to grinding parameters. The laser induced con-trollable crack characteristics on the grinding process are conducive to realizing the con-trol of surface and subsurface grinding damage of brittle materials.

Abstract: The robotic arm of the Wentian module can complete tasks such as supporting astronauts' extravehicular activities, installing and maintaining payloads, and inspecting the space station. The 7-joint SSRMS manipulator is critical for space missions. This study aims to build its kinematic model via screw theory. It simplifies SSRMS to right-angle rods, defines joint screw axes, twist coordinates, and initial pose matrix. Using PoE formula, the 7-DOF forward kinematics equation is derived. Besides, it derives fixed joint angle for inverse kinematics, including analytical solutions and numerical solutions. It elaborates analytical solutions for fixing joints 1/7 and 2/6 and numerical solutions for fixing joints 3/4/5,solves all joint angles via kinematic decoupling, and addresses special cases. Experiments with China’s space station small arm parameters show The probability of meeting the accuracy threshold of 10−4 is 99.79%,verifying model effectiveness, while noting singularity-related weak solving areas. This provides a reliable basis for subsequent inverse kinematics optimization.

Abstract: This study investigates the utilization of Abies Alba exudate resin for the development of hybrid resins intended as matrices for composite materials. Two formulation routes were explored: (i) dilution of spruce resin in turpentine derived from pine buds, and (ii) dilution in food-grade ethanol (96%). The diluted resins were subsequently blended with an epoxy resin, whose addition initiated polymerization and enabled the formation of a solid hybrid matrix. The resulting hybrid resins were characterized by multiple testing methods and further applied in the fabrication of cotton fiber–reinforced composites.

Abstract: This study presents a comparative analysis of the economics of batch and continuous lubricant supply process strategies in internal combustion engines (ICEs). A phenomenological model based on mass balance equations was developed to describe the dynamics of lubricant precursor depletion, film formation, and film removal under both supply strategies. The results demonstrate that the continuous supply system achieves a steady-state condition that ensures stable film thickness and a significant reduction in lubricant consumption compared with the batch strategy. Sensitivity analyses reveal that both the kinetic constant and the film removal rate strongly influence lubricant make-up requirements, defining a feasibility region for process operation. Under supercritical conditions, the batch strategy exhibits rapid precursor overconsumption; in contrast, the continuous strategy maintains minimal excess. The findings suggest that continuous lubrication process strategy can substantially improve economic and environmental performance in ICEs when properly designed and operated within feasible kinetic and mechanical limits.

Abstract: Ultrasonic vibration-assisted grinding (UVAIG) is a continuous-contact grinding process. In this process, the arc length of engagement for a single abrasive grain is longer compared to conventional grinding, which enhances the quality of the processed surface and improves processing efficiency. This study aims to establish a three-dimensional model of abrasive grains in space and to theoretically deduce the trajectory of abrasive grains during axial ultrasonic vibration-assisted internal grinding (UVAIG), as well as the resulting surface quality, measured as Ra. A three-dimensional simulation tool for ultrasonic vibration grinding micro-surfaces is developed using MATLAB. This tool enables the analysis of how various processing parameters affect workpiece surface morphology. Additionally, a predictive model is established for UVAIG simulations, allowing theoretical calculation of surface topography changes induced by different processing parameters, vibration settings, and abrasive grain models.

Abstract: An integrated structural parameter optimization method is presented to improve the vibration performance of medical rotating systems. Key geometric and material parameters were selected using sensitivity analysis, and a response surface model was constructed based on 48 finite element simulations. The optimization objective was to minimize vibration displacement under operational speeds between 300 and 900 rpm. Results indicate that optimized designs reduced maximum vibration displacement by 31.2% while maintaining structural stiffness within ±5% of the original design. The proposed framework provides an effective pathway for vibration reduction without introducing additional damping devices.

Abstract: This study numerically investigates how welding parameters influence the dynamic stability of medical equipment frames. A set of 30 frame models with varying weld bead sizes and heat inputs was analyzed using finite element modal and harmonic response analysis. The first natural frequency varied between 62 and 91 Hz depending on welding conditions, leading to up to 2.1-fold differences in resonance amplification factors. The findings indicate that welding design plays a critical role not only in static strength but also in dynamic performance and service life of medical equipment.

Abstract: Residual unbalance moments are a major source of vibration in rotating medical devices. This study proposes an adaptive control strategy to suppress residual unbalance moments based on real-time vibration feedback. A rotating structure model with distributed mass eccentricity was established, and adaptive gain tuning was implemented using acceleration signals sampled at 2 kHz. Simulations under three unbalance levels (120, 220, and 350 g·mm) show that the proposed method reduced peak vibration acceleration from 1.42 m/s² to 0.79 m/s² on average, corresponding to a 44.4% reduction. The approach demonstrates strong robustness against speed variation and sensor noise, making it suitable for medical rotating equipment.

Abstract: Contemporary physiotherapy requires technological tools to provide effective therapy to the increasing group of patients, neurological, among others. This can be achieved with rehabilitation robots, which can also be exoskeletons - wearable devices mobilizing multiple joints with complex motions representing activities of daily living. To perform the kinesiotherapy conveniently in home-like environments, the exoskeletons need to be relatively lightweight. The paper presents the methodology of decreasing the mass of the exoskeleton design with the human-in-the-loop simulations of motions, followed by multibody dynamics simulations, and finite element method (FEM) multistep optimization. The process includes sequential initial parametric optimization, topology optimization, and final parametric optimization. The steps are used to set initial dimensional and material parameters, extract new geometrical features, and adjust the final geometry dimensions of a new design. The presented case of the SmartEx-Home exoskeleton resulted in a total mass reduction of almost 50% while meeting the criteria of the minimum safety factor and maximum internal stress and strain for all the components. The final design is being manufactured and will be used within the tests with humans, reflecting almost fully automatic passive and active therapy.

Abstract: This study presents a dynamic balance control method for CT gantry systems using a high-fidelity multi-body dynamics model with modal coupling effects. The gantry structure was modeled with 14 rigid bodies and 22 flexible modes identified from modal testing data. Unbalance disturbances equivalent to 50–300 g·mm were introduced to evaluate system response. Simulation results show that unbalance-induced vibration amplitudes increased by up to 62% near critical speeds. By integrating modal feedback into the balance control algorithm, the proposed method reduced radial vibration by 38.5% and rotational torque fluctuation by 41.3% across operating speeds from 0.5 to 2.5 r/s, improving mechanical stability and imaging reliability.

Abstract: Over the centuries, many birds have gone extinct, and many are currently endangered due to anthropogenic activities, inability of some birds to compete for food and the negative effects of climate change. To promote biodiversity of rare birds requires deliberate human efforts to create ecosystems that conserve them and enhance their survival. This work implemented a design-driven solution to an identified problem of squirrel feeding on bird seeds. Thus, it reports the design, development, prototyping and testing of a squirrel-proof birdfeeder capable of selectively preventing squirrels but allowing birds to feed from it. The design comprised of a compression spring and two concentric cylinders. Finite Element Analysis and Failure Mode and Effect Analysis were used to optimise the structural design and functionality of the bird feeder. Testing of the bird feeder showed that birds successfully fed from it, whilst squirrels could not access the feeds due to the mass differential mechanism based on Hooke’s law. Camera-recoded interactions showed that when a squirrel exerted its weight anywhere on the surface of the feeder, the spring compressed to displace the outside surface downwards to close-off the feeding holes and prevented a squirrel from accessing the bird seed. The prototype is a reliable solution to the problem of squirrels consuming bird seeds at home and in the parks.

Abstract: Structural vibration is a significant problem created by industrial machinery (i.e., compressors, motors, and generators) that can negatively affect the performance of equipment as well as the overall integrity of buildings or structures. Although various vibration isolation technologies are available for reducing the structural vibrations produced by machinery, most of these methods have inherent limitations because of a lack of sufficient damping at lower frequencies relative to that observed higher frequency ranges. The purpose of this paper is to evaluate the use of advanced vibration isolation technologies using re-entrant auxetic structures that are characterized by their negative Poisson ratios. Through a comprehensive evaluation of 92 published articles within the areas of auxetic unit cell design and topology optimization, the mechanics of materials related to negative Poisson ratios, energy absorption mechanisms, vibration reduction in sandwich structures, and dynamic analyses of frame and plate systems, this review presents the current state-of-the-art re-entrant auxetic structures that can be employed as vibration isolation technologies for machine foundations. The analysis reveals that compared with standard structures, re-entrant geometry-based structures exhibit high levels of energy absorption (up to a 767% increase over the standard designs), along with superior vibration isolation characteristics. A hybrid approach utilizing combinations of geometric modification, multimaterial fabrication, and foam filling is identified as the most promising method for optimizing the relationship between stiffness and damping capacity. Additionally, advancements in additive manufacturing have made it possible to fabricate complex auxetic geometries that were previously unfeasible via traditional processes. In addition to identifying significant research gaps, such as scaling up to large macroscale steel implementations, this paper presents general design guidelines for future vibration isolation systems for industrial machinery.

Abstract: Core body temperature (CBT) is a fundamental physiological parameter tightly regulated by thermoregulatory mechanisms and is critically important for heat stress assessment, clinical management, and circadian rhythm research. Although invasive measurements such as pulmonary artery, esophageal, and rectal temperatures provide high accuracy, their practical use is limited by invasiveness, discomfort, and restricted feasibility for continuous monitoring in daily-life or field environments. Consequently, extensive efforts have been devoted to developing non-invasive CBT measurement and estimation techniques. This review provides an application-oriented synthesis of invasive reference methods and representative non-invasive approaches, including in-ear sensors, infrared thermography, ingestible telemetric sensors, heat-flux-based techniques, and model-based estimation using wearable physiological signals. For each approach, measurement principles, accuracy, invasiveness, usability, and application domains are comparatively examined, with particular emphasis on trade-offs between measurement fidelity and real-world implementability. Rather than ranking methods by absolute performance, this review highlights their relative positioning across clinical, occupational, and daily-life contexts. While no single non-invasive technique can universally replace invasive gold standards, recent advances in wearable sensing, heat-flux modeling, and multimodal estimation demonstrate growing potential for practical CBT monitoring. Overall, the findings suggest that future CBT assessment will increasingly rely on hybrid and context-aware systems that integrate complementary methods to enable reliable monitoring under real-world conditions.

Abstract: This study develops an analytical description of the motion of dilute solid particles in the boundary layer of laminar horizontal flows subjected to weak transverse pulsations. A coupled matrix representation of the governing equations is formulated, and closed-form solutions are obtained using Laplace transformation. The analytical expressions capture transient evolution, forced oscillations, resonance effects, and long-term behaviour for particles with different density ratios. Numerical evaluation shows that light particles migrate toward faster regions of the boundary layer and accelerate longitudinally, while heavy particles move toward slower layers and decelerate. Transverse pulsations generate oscillatory trajectories whose amplitude increases near resonance. Impulsive perturbations superimposed on the continuous motion lead to discontinuous transitions consistent with the linear matrix system. The results provide a unified physical interpretation of particle redistribution mechanisms in boundary layers and offer a compact analytical tool for dilute multiphase flow modelling.

Abstract: The wayaprinted ink droplet dries is just as important as how it is deposited. During evaporation, the liquid inside the droplet circulates, the interface cools, and the solvent composition changes. These coupled processes control where non-volatile solutes and particles accumulate, which ultimately affects the uniformity, microstructure, and electrical performance of printed metallic features. In this work, we present a time-dependent multiphysics model of a sessile reactive silver-ink droplet composed of a binary solvent mixture (water and ethylene glycol) on a heated substrate. A two-dimensional axisymmetric model is implemented in COMSOL Multiphysics by coupling Laminar Flow (Navier Stokes), Heat Transfer in Fluids, and Transport of Concentrated Species (Maxwell–Stefan diffusion), along with a moving interface representation to account for evaporation-driven shrinkage. The formulation captures evaporation-driven capillary flow, thermocapillary Marangoni stresses caused by evaporative cooling, and solutal Marangoni stresses caused by preferential evaporation and solvent segregation. The simulations predict (i) strong, transient internal circulation; (ii) spatially non-uniform temperature fields; and (iii) progressive enrichment of ethylene glycol near the liquid–vapor interface and especially near the contact line. These results provide a practical, physics-based framework to interpret common drying outcomes such as ring-like deposition versus more uniform coatings, and they offer guidance for optimizing solvent ratios and substrate temperature in inkjet printing.

Abstract: Background: Impact wrenches are widely used in construction and automotive industries, yet they generate harmful vibrations that pose health risks to operators and reduce tool usability. Methods: A practical, low-order bond graph model of impact-wrench dynamics is developed, capturing interactions among the motor, hammer, anvil, and hand/arm constraints. The model is validated against measurements during bolt setting in a steel plate. Results: Predictions match measured RMS accelerations and spectral modes up to 200 Hz with errors within 11%. Analysis attributes the dominant vibration sources to rotational and translational impacts between the hammer and anvil; notably, the translational (z-axis) impact contributes substantially to felt vibration while not being required for bolt tightening. Conclusions: The model provides physical insight into vibration origins and supports actionable design decisions (e.g., eliminating the linear impact, adding rotational damping/control) consistent with ISO 28927-13:2022 testing practice.

Abstract: This paper investigates the structured deployment of a project oversight framework within a small-scale enterprise characterized by low project management maturity and limited resource capacity. Adopting a hybrid operational strategy that blends predictive planning with agile responsiveness, the study documents the customization and implementation of a digital project tracking platform tailored to diverse project environments. Data were gathered through embedded organizational roles, unstructured feedback loops, and direct observation, capturing stakeholder challenges and behavioral resistance during change adoption. The findings reveal critical gaps in formal process uptake, technology assimilation, and leadership alignment. Based on experiential evidence, a revised integration roadmap is proposed, emphasizing incremental adoption, simplification of planning tools, and deeper managerial engagement. This research contributes actionable insights for small enterprises aiming to institutionalize project governance systems aligned with operational realities.