Search Results (1,747)

Magnesium-based alloys remain poorly researched, particularly regarding their behavior and resistance under hydrodynamic loading conditions. Interest in these materials is driven by their low density, lower even than that of aluminum alloys, and their excellent pressure die-casting capability, leading to manufacturing components with high geometric accuracy and structural homogeneity. Due to their biodegradability and biocompatibility, recent research has focused on using them in reconstructive surgery devices, similar to Zn-Mg alloys. As the blood circulatory system can, at certain stages, be considered similar to a hydraulic system, it is subjected to hydrodynamic flow regimes, including cavitation erosion. In this context, the current research, conducted on the AM50 magnesium-based alloy, provides new insights into its behavior and structural resistance exposed to shock waves and microjets generated by cavitation. Cavitation tests were performed using a standard 20 kHz vibratory device on three material conditions: one semi-finished (initial) state and two aged, heat-treated states at 200 °C for 12 and 24 h. Analyses of the characteristic erosion curves, cavitation resistance parameters, and macro- and microstructural examinations of the eroded surfaces revealed that, compared with the semi-finished condition, the applied heat-treatment regimes increased the HV₅ hardness by 6.8–17% and the cavitation resistance by 27–61%. Full article

Functional properties of caseins play a crucial role in the dairy industry, so it is important to develop methods to improve their functionality. The aim of this study is to investigate the combined effect of high-intensity ultrasound (HIUS) treatment and calcium chelation on functional properties of casein micelles. For this purpose, micellar casein concentrate (MCC) was prepared with a concentration of 3% (w/w) casein. Then, 0 and 10 mM of Disodium hydrogen phosphate was added. HIUS was performed at a frequency of 20 kHz, power intensity of 550 W/cm², and an amplitude of 100% for 0, 5, 10, 15, and 20 min at 25 °C. Factorial design was employed to investigate the effect of ultrasound time (UST) and disodium phosphate (DSP) on foam capacity (FC), emulsion activity index (EAI), gelation time (GT), G′ at 480 min of oscillation time (G′₄₈₀), slope of complex viscosity, and linear viscoelastic region (LVR). At 0 mM of DSP, increasing UST from 0 to 15 min decreased GT from 114.39 ± 3.20 to 83.52 ± 1.61 min, and it extended LVR from 40.36 ± 0.12 to 41.27 ± 0.27% of the applied strain. In addition, applying HIUS for 15 min increased the elasticity and firmness of MCC gel networks at 0 mM of DSP. G′₄₈₀ was not influenced by UST, but it was reduced by DSP from 108.40 ± 3.29 to 15.78 ± 1.58 Pa. Increasing both UST and DSP significantly increased FC from 110.00 ± 13.23 to 163.33 ± 11.55% and foam stability (FS) in all treatments. FS reached its maximum (doubled) after 10 min of UST at 0 mM of DSP. However, EAI and emulsion stability index (ESI) decreased with increasing both UST and DSP. HIUS treatment combined with calcium chelation might highlight a new approach to improve foaming properties. However, regardless of calcium chelation, HIUS treatment is a promising technology to improve the gelling properties of casein micelles. Full article

This study investigates the reliability of power-terminal solder joints in intelligent power modules (IPMs) subjected to thermal cycling, random vibration, and packaging/assembly-induced deformation. Fifty IPMs were tested under temperature cycling from −55 °C to 125 °C and random vibration from 20 to 2000 Hz, and the experimental observations were combined with finite element simulations of thermal, vibration, and deformation loads. The modules survived 200 temperature cycles in the free state, whereas functional abnormalities occurred after board-level assembly and subsequent environmental loading. Simulation results showed that random vibration produced limited solder-layer stress because the first structural mode was above the excitation range, while packaging and PCB deformation markedly increased the initial stress of the power-terminal solder joints. When local deformation reached approximately 0.5 mm, the calculated solder-pad stress reached or exceeded the shear-strength risk range, consistent with the failure tendency observed in highly deformed modules. Weibull analysis further indicated a fatigue-dominated failure process with an increasing failure rate. These findings suggest that deformation control, package stiffness improvement, and assembly flatness management are critical for improving the reliability of IPM power-terminal solder joints. Full article

Objectives: We aimed to descriptively evaluate the feasibility and clinical utility of TowardPi BO (4K ultra-HD microscope integrated with a 400 kHz swept-source intraoperative optical coherence tomography (SS-iOCT) system) in managing various ophthalmic surgical conditions in a real-world setting. Methods: We analyzed surgical videos and data from 123 consecutive cases that underwent elective surgery with the assistance of this SS-iOCT system at Beijing Tongren Hospital between 2 September 2025 and 10 February 2026. Cases were included when the iOCT provided critical, real-time information that directly influenced surgical decision-making or technique modification. Cases were excluded if iOCT served only routine confirmatory or educational purposes without altering the surgical plan. Results: A total of 72 surgical cases were included, comprising 7 intraocular lens implantations with ciliary sulcus fixation, 19 macular holes, 3 cases of macular hole retinal detachment (MHRD), 4 cases of macular schisis with or without foveal detachment (MSRD), 12 cases of submacular hemorrhage, 20 cases of rhegmatogenous retinal detachment (RRD), and 7 intraocular mass lesions. The 400 kHz SS-iOCT significantly aided in surgical visualization, guided real-time decision-making, and prompted modifications in surgical techniques. Conclusions: To our knowledge, this is the first real-world study to evaluate the application of a 400 kHz SS-iOCT system across a wide spectrum of ophthalmic conditions, including its novel use in intraocular tumors. From routine to complex surgical cases, SS-iOCT enhances surgical precision and facilitates real-time decision-making, ultimately contributing to improved surgical outcomes. Full article

AlCoCrFeNi high-entropy alloy coatings reinforced with different TiN contents (2 wt.%, 4 wt.%, and 6 wt.%) were fabricated on 304 stainless steel by laser cladding. The effects of TiN addition on the microstructure, hardness, friction behavior, and wear resistance of the coatings were investigated. Dry reciprocating sliding tests were conducted under a load of 10 N, a frequency of 5 Hz, a stroke length of 5 mm, and a duration of 20 min using GCr15 bearing steel balls as the counterpart. The results showed that the 2 wt.% TiN coating exhibited the best tribological performance within the investigated composition range, with a microhardness of 579.6 HV_0.5, a relatively low and stable friction coefficient of approximately 0.30–0.35, and a wear rate of 2.9 × 10⁻⁴ mm³/(N·m). When the TiN content increased to 4 wt.% and 6 wt.%, the wear resistance decreased, which was mainly associated with particle agglomeration, local stress concentration, and brittle spalling. These results indicate that appropriate TiN addition can improve the load-bearing capacity and wear resistance of laser-cladded AlCoCrFeNi coatings, providing a potential surface-strengthening strategy for 304 stainless steel components under dry sliding conditions. Full article

Reflection silencers are installed in the exhaust system of stationary combustion engines to attenuate low-frequency noise by means of destructive interference. The acoustic properties of mufflers are experimentally determined by the standard two-load method, which only considers measurements without mean flow. In real engine operation, however, exhaust mass flow is always present. Measurements are significantly more complex and expensive if fluid flow is taken into account, which is why the available data is limited. Thus, the impact of mean flow on the attenuation of silencers is not clearly known yet. This work contributes to the state of the art by quantifying the influence of the Mach number on the transmission loss of double-tuned straight-through mufflers based on reproducible, noise corrected measurement results that include uncertainties. A frequency range between 20 Hz and 891 Hz is investigated at eleven different Mach numbers between 0 and 0.1 under ambient conditions. It is found that resonance peaks diminish with increasing Mach number, while other frequencies remain unaffected by mean flow. These findings can be transferred to operating conditions of stationary combustion engines and other exhaust systems. The experimental data will serve as a basis for the validation of analytical and numerical models in subsequent work. Full article

The aim of this study was to evaluate the effect of two laser-assisted disinfection techniques on the porosity and bond strength (BS) of a new premixed calcium silicate sealer. Forty extracted human single-rooted premolars with one root canal were prepared up to 50/05. Samples were randomly assigned to the groups (n = 10 each): 1. shock wave-enhanced emission of photoacoustic streaming (SWEEPS) (20 mJ, 15 Hz, 0.60 W, pulse duration 25 µs), 2. diode laser (975 nm, 1.5 W), 3. conventional needle and syringe irrigation (CI), and 4. control (C), with no final irrigation protocol. Root canals were filled with a premixed calcium silicate sealer using the single-cone obturation technique. Micro-CT scans were performed after two weeks to determine the presence of voids in the filling. Dentinal discs from the middle third were prepared for push-out testing. Kruskal–Wallis and post hoc Dunn tests were used, with significance set at 5%. Micro-CT analysis detected porosity in all samples, with no significant differences among the groups (p > 0.05). SWEEPS showed the highest BS values (median 3.233 MPa) and outperformed CI and C (median 1.923 and 1.989 MPa) (p < 0.05) overall. SWEEPS enhanced the BS compared with CI. Voids were present in all experimental groups. Full article

In industrial applications such as in situ leaching and uranium mining, permanent magnet synchronous motors (PMSMs) for submersible pumps are frequently connected to frequency converters via long cables. During this long-distance transmission, traveling wave reflections induced by high-frequency pulse width modulation (PWM) generate severe transient overvoltages that threaten motor insulation. Because installation space at deep-well motor terminals is severely restricted, overvoltage suppression must be implemented at the inverter output. Here, the parameter design and optimization of a passive LC filter specifically developed for 250 Hz high-frequency PMSMs are presented. The optimal inductance and capacitance parameters were determined by balancing multiple operational constraints, including fundamental voltage drop, high-frequency harmonic attenuation, and the avoidance of low-order harmonic resonance. Furthermore, the anti-saturation performance of the magnetic core material, evaluated thermal characteristics through electromagnetic-thermal co-simulation, and analyzed the risk of self-excited oscillation between the filter capacitors and the motor was analyzed. Finally, hardware experiments conducted on a 20 m cable test bench validate that the designed LC filter effectively mitigates terminal overvoltage. The peak terminal voltage was reduced from 900 V to 505 V, and total harmonic distortion (THD) was limited to below 5%. This design provides a highly reliable, space-efficient solution for overvoltage suppression in high-speed, long-cable motor drive systems. Full article

Background: Er:YAG laser (λ = 2940 nm) biomodification of the implant osteotomy site removes the smear layer after rotary preparation and may enhance bone-implant contact. This randomized controlled clinical study evaluated implant stability dynamics following Er:YAG laser biomodification using resonance frequency analysis (RFA). Methods: Ninety patients were randomized 1:1 into a case group (n = 45; rotary osteotomy + Er:YAG biomodification; 400 mJ, 17 Hz) and a control group (n = 45; rotary osteotomy alone). Implant stability quotient (ISQ) was measured by RFA in vestibulo-oral (VO) and mesiodistal (MD) directions at placement, days 10, 20, 30, and month 3. Results: The case group showed significantly higher ISQ values at all time points in both directions (t-test, p < 0.05). Repeated measures ANOVA revealed a significant time × group interaction in the MD direction (F = 14.461, p < 0.001, partial η² = 0.341). Primary VO ISQ: 75.04 ± 4.27 (cases) vs. 72.29 ± 3.38 (controls); primary MD ISQ: 76.49 ± 4.29 vs. 72.89 ± 2.29. The proportion achieving ISQ ≥ 70 was consistently higher in the case group. Conclusions: Er:YAG laser biomodification combined with rotary osteotomy yields higher, more stable ISQ values throughout early healing in mandibular D2/D3 bone, potentially supporting shorter healing intervals and early loading in selected clinical situations. Full article

This paper reports the development of a Class-A amplifier that operates at 50 MHz and 400 °C. The amplifier utilizes a commercially available 4H-SiC static induction transistor (SIT) as the active device and incorporates input/output-matching networks to optimize amplifier operation and DC bias networks, which comprise thin-film spiral inductors, metal–insulator–metal (MIM) capacitors, and thick-film chip resistors. All passive components were tested at frequency and temperature prior to amplifier development and are reported. A small-signal SiC SIT model that was developed in Keysight’s Advanced Design System (ADS 2023) software suite was used to design and optimize the amplifier’s performance. The SiC SIT amplifier’s S-parameters were recorded for frequencies between 20 and 100 MHz over a temperature range of 25 °C to 400 °C, exhibiting a gain (S₂₁) of approximately 15.8 and 5.80 dB at 25 °C and 400 °C, respectively. The input and output reflection coefficients at 50 MHz and 400 °C were −18.5 and −15.2 dB, respectively. The noise figure and phase noise were measured at temperatures between 25 °C and 400 °C. At 50 MHz, the noise figure increased by only 21% over the temperature range, while the 1 kHz offset of the phase noise remained below −110 dBc/Hz. The stability factor, K, calculated using both measured and simulated data, demonstrates unconditional stability over the frequency range at 400 °C. Lastly, the 1 dB compression point was measured at 50 MHz and 400 °C with an approximated output of 9.5 dB. Simulated and measured results are presented and show the model is within 10% error at 400 °C. Full article

It has been observed in prior research that high thermal impact—resulting from a large temperature difference between hot water vapor and cold liquid water—can enhance the thermal performance of cavitation-induced low-energy nuclear reactions (LENRs) in water, with an estimated increase in the coefficient of performance (COP) of approximately 50% for every 100 °C temperature rise. The temperature of the hot water vapor is primarily determined by the boiler output, which typically represents the highest temperature source and plays a dominant role in reactor performance. In this study, a flow oscillator was designed as an thermal conditioning component for these potential LENR reactor systems using linear flow network analysis (LFNA) to generate flow resonance that elevates the hot vapor temperature, thereby increasing thermal impact and improving LENR performance. LFNA is based on the linearization of the fluid flow equations governing mass and momentum transport and utilizes a fluid-electric circuit analogy. For a fluid flow system, various components can be modeled using analogs of electrical resistance, capacitance, and inductance (R, C, and L), allowing the system behavior to be analyzed similarly to an RLC circuit. Through this analogy, flow resonance phenomena can be predicted, potentially enabling the generation of high-temperature and high-pressure responses that are beneficial to LENR processes. The analytical model was experimentally validated and subsequently applied in the LENR reactor design. The analytical result shows that an output temperature difference exceeding 350 °C can be achieved using a 0.5 m pulse tube at a 46 Hz triggering frequency with 20 kPa perturbation, which indicates a potential COP enhancement of 175% based on prior studies. The result provides a potential mechanism to significantly enhance the thermal impact conditions and promote LENR performance in water-based reactor systems. Full article

Background: This study analyzed spectral alterations of heart rate variability (HRV) in Williams syndrome (WS) during sleep, taking into account the multi-fractal properties of RR-interval spectra, including effects of aging and sleep structure. Methods: Using ECG recordings of 20 subjects with WS and matched typically developing (TD) controls, fractal and oscillatory spectral components of RR-intervals were computed. The fractal component was parametrized with a piecewise-linear function, allowing a breakpoint and separate slope and intercept values in the lower- and higher-frequency domains. The dominant peak frequency and prominence were extracted from the LF (0.04–0.15 Hz) and HF (0.15–0.4 Hz) bands. Results: Strong WS/TD group differences were found in the breakpoint frequency, high domain slope, intercept and HF peak prominence. The LF peak frequency showed a slight age-dependent decrease only in TD, and reduced values in WS independent of age. Principal component analysis identified a main fractal component describing typical alterations in the spectrum in WS, which exhibited sleep-structure associations. Conclusions: The broken power-law model successfully characterized the fractal component of RR-interval spectra, capturing altered cardiac regulation in WS, while suggesting the fractal parameters as possible biomarkers of the degree of general autonomic deregulation. Full article

Low-frequency traffic noise below 500 Hz is difficult to mitigate because its long wavelengths require impractically large conventional resonators. Here, we report an active-learning-guided inverse-design approach for scalable phononic-crystal-based acoustic metamaterial resonators that simultaneously suppress low-frequency noise transmission and harvest acoustic energy. The approach combines Gaussian process regression surrogate modeling with genetic algorithm optimization to efficiently explore high-dimensional cavity geometries. By iteratively retraining the surrogate with FEM-validated designs, the active-learning process guides the search toward high-performance structures while reducing costly FEM evaluations compared with conventional GA optimization. After geometric scaling, the 2.5D prototype derived from the nine-point optimized cavity achieved a pressure amplification factor of approximately 20 near 490 Hz, while the revolved 3D cavity exhibited amplification exceeding 30 and a transmission loss of approximately 14 dB near the target frequency. Integrated with a mass-loaded five-PZT stack, the device generated 5.5 V_pp and 0.25 mW under 100 dB SPL, corresponding to a normalized power density of 0.58 μW Pa⁻² cm⁻³. These results demonstrate a route toward multifunctional piezoelectric acoustic devices for noise mitigation, localized energy harvesting, and self-powered sensing. Full article

Tool wear in CNC milling increases friction and torque demand at the tool-workpiece interface, which is reflected in spindle motor current. This study develops a non-intrusive tool wear condition classification method using spindle motor current monitoring during practical CNC milling of commercial medium-carbon steel workpieces (JIS S50C/AISI SAE 1050-equivalent; as-received and non-heat-treated; nominal laboratory hardness approximately 4.3 HRC). Experiments were performed on a Tongtai MDV-508 vertical machining center at fixed cutting conditions (3000 rpm spindle speed, 2 mm axial depth of cut, 5 mm cutting width, and 300 mm/min feed rate) using eight TiAlN-coated fine-grain WC–Co solid carbide end mills (10 mm diameter, four flutes; nominal Co binder approximately 10 wt%). An oil-based HS Highstart/HS-SSHS-BH10 cutting fluid was applied through the machine external coolant nozzle in flood mode at an estimated nominal flow rate of approximately 3 L/min and near-room coolant temperature (25 ± 2 °C), and was used as supplied without dilution. A clamp-type AC current sensor was installed on one phase line supplying the spindle motor, and current was acquired using an NI-9221 module at 20 kHz. Cutting intervals were isolated by envelope-based segmentation, concatenated, and divided into 1 s windows (0.5 s overlap) for feature extraction. Three feature sets were evaluated: time-domain statistics, frequency-domain statistics, and an FFT→PCA hybrid representation. Tool states (New, Mid-life, Old) were labeled using post-process surface roughness Ra thresholds supported by microscope observation. The PCA transformation was fitted only on training data and then applied to the held-out test data. A logistic regression classifier achieved 97.44% test accuracy (152/156 windows; 95% Wilson CI: 93.59–99.00%) with the PCA-hybrid features, outperforming time-domain (89.74%) and frequency-domain (94.87%) models. The results support spindle current monitoring as a low-cost approach for quality-aligned tool condition monitoring, while the external validity remains limited to the tested machine, material, tool, coolant, and cutting-parameter combination. Full article

Pumping stations serve as the foundation platform for large-scale vertical fluid machinery, and their structural dynamics directly govern the vibration levels and long-term reliability of the installed pump units. In low-head vertical pumping stations, the interaction among the massive underwater substructure, flexible above-ground powerhouse, and surrounding backfill soil creates a complex dynamic system whose behavior remains insufficiently characterized. This study presents a comprehensive dynamic analysis of a large-scale vertical pumping station using a high-fidelity three-dimensional finite element model that incorporates the powerhouse superstructure, submerged concrete substructure, and backfill soil. Modal analysis under four boundary condition scenarios—varying in soil participation and interface contact conditions—systematically quantifies the influence of soil–structure interaction on natural frequencies and mode shapes. Resonance verification against three primary excitation sources—rotational frequency (4.917 Hz), blade passage frequency (24.583 Hz), and rotor–stator interaction frequency (196.667 Hz)—is extended from the first 50 modes to the 400th mode to assess potential high-order resonance risks. Results show that the roof slab, with its large span and low stiffness, exhibits the highest vibration susceptibility. For the rotational frequency, modes 4–12 fall below the 20% code-specified safety margin but rapidly exceed the threshold thereafter. For the blade passage frequency, the separation ratio decreases progressively with increasing mode order within the first 50 modes, and the extended analysis up to the 400th mode shows that the separation ratio remains well above 20% throughout modes 51–400. Consequently, no substantial resonance risk exists for the blade passage frequency within the entire computed range. The rotor–stator interaction frequency remains safely separated with margins exceeding 95%. These findings demonstrate the profound influence of soil–structure interaction and confirm that, despite a decreasing trend in frequency separation at higher orders, the blade passage frequency poses no substantial resonance risk up to the 400th mode. This work provides a rigorous analytical framework for vibration-informed design and optimization of pump foundation systems, with direct implications for the reliability and operational safety of large-scale vertical fluid machinery. Full article