Search

Introduction: Planetary-face gears combine the advantages of both planetary and face gears, offering potential value for wind power applications. During the gear meshing process, a large amount of heat is generated, and tooth wear also occurs, which affects transmission performance. Methods: Analyzing multiple factors such as lubrication performance and thermal effects of meshing pairs plays a crucial role in improving the overall lifespan of transmission systems. This study developed a nonlinear dynamic model of a wind power planetary-face gear system, considering factors like random wind load, tooth surface friction, temperature rise, tooth side clearance, and elastic lubrication. Nonlinear methods such as bifurcation diagram, maximum Lyapunov exponent diagram, and time-frequency diagram were used to analyze the effects of wind turbine radius, average wind load, temperature rise, and lubricant viscosity on the dynamic response of the gear transmission system under random wind loads. Results: The results show that selecting an appropriate wind turbine radius for different wind loads is essential to enhance system stability. Higher lubricant viscosity can suppress chaotic phenomena in gear systems. For a well lubricated gear system, tooth surface temperature rise is a key factor affecting the dynamic characteristics of the system. Discussion: This article aims to provide valuable insights into improving the operational stability of the wind turbine planetary gear system. [ABSTRACT FROM AUTHOR]

With the growing awareness of healthy lifestyles, the antibacterial properties of textile materials have become a hotspot in market research and product development. Textile antibacterial technology effectively inhibits bacterial growth, improving comfort and health during wear, making it widely applicable in daily life, sports, and medical fields. However, traditional antibacterial treatment methods face several challenges, such as poor durability of antibacterial effects and high sensitivity to temperature variations, which presents new research directions for improving the antibacterial properties of textile materials. Many studies have attempted to improve the antibacterial performance of textiles through chemical treatments, nanotechnology, and other means, but most focus on single materials or factors and lack in-depth exploration of the combined effects of multiple factors. Additionally, existing antibacterial performance tests often overlook the behavior of textiles under different temperature conditions, leading to certain limitations in evaluating their antibacterial effectiveness. To address these issues, thermodynamic principles, particularly multivariable linear regression analysis, have become a new trend in research, as they can comprehensively consider the influence of multiple factors on antibacterial performance and predict outcomes through regression models. This study consists of two main parts: firstly, a multivariable linear regression analysis to explore the impact of temperature rise on the antibacterial performance of textile materials, and the establishment of a corresponding predictive model; secondly, practical antibacterial performance tests to verify the effectiveness and practicality of the regression model. The research findings help uncover the mechanisms by which temperature changes affect the antibacterial performance of textiles and provide new theoretical and technical support for improving the antibacterial functionality of textile materials. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study designed a method to determine the relationship between axial preload, temperature, and dynamic characteristics. The ball-bearing dynamic model analyzed the dynamic characteristics of a ball bearing subjected to axial preload and thermal expansion based on the Hertz contact and gyroscopic moments. By increasing the temperature, the inner contact state of the ball bearing was altered, resulting in reduced vibration of the rotor system and increased stiffness of the rotor system. Simulation data indicated that at a temperature of 40 °C, the corresponding loads of both the inner and outer rings exhibit an increase of 5.2% and 5.1%, respectively. Experimental data suggested that as the temperature increased, both the peak-to-peak and root-mean-square values of the rotor vibration decreased, while the rotor stiffness exhibited a linear increase with rising temperature. This study provided a real-time temperature control method for vibration control of rotor system. [ABSTRACT FROM AUTHOR]

Drilling for implant site preparation generates heat, which can cause bone necrosis if temperatures exceed 47 °C for over a minute. Factors influencing heat include drill size, speed, pressure, irrigation, and tool wear. Frequent drill replacement is essential, as wear from repeated use and sterilization affects performance. This study compared three pilot drills with similar designs from different manufacturers, testing each on pig ribs for 15 perforations after 15 sterilization cycles. Researchers measured temperature increase, drilling time, and surface wear. Results showed that drill no. 1 generated more heat than drills no. 2 and no. 3, though none reached critical temperatures. Drill no. 2 took the longest to reach the desired depth and displayed the most deformation. Findings highlight the importance of adhering to the recommended operational limits, suggesting that drills should be replaced after 15 cycles to ensure efficacy and patient safety. [ABSTRACT FROM AUTHOR]

(1) Background: This study investigates the effects of curing light intensity, exposure time, and distance on the Vickers microhardness (VMH), hardness bottom-to-top ratio (HR), and temperature rise (TR) of conventional dental resin-based composite (RBC). (2) Materials and Methods: Specimens of one conventional RBC (Tetric EvoCeram, Ivoclar Vivadent) were cured with 12 different curing protocols (CPs), created with three different light intensities (Quartz Tungsten Halogen 300 mW/cm2, LED 650 mW/cm2, LED 1100 mW/cm2), two exposure times (20 and 40 s), and two distances of curing tip (0 and 8 mm). The VMH of top (VMH-T) and bottom (VMH-B) surfaces was measured. The hardness bottom-to-top ratio (HR) was calculated from VMH-B and VMH-T. The HR below 80% was rated as inadequate polymerization. The TR at the depth of 2 mm within the RBC was measured using a K-type thermocouple. Data were analyzed using Levene's test and the multivariate analysis of variance (MANOVA). The level of significance was set at p < 0.05. (3) Results: Exposure time and distance significantly influenced VMH-B and HR. Increased distance significantly reduced VMH-B, HR, and TR. CPs 300 mW/cm2/8 mm/20 s and 650 mW/cm2/8 mm/20 s produced inadequate polymerization (HR < 80%). Prolonged exposure time produced higher values of VMH-B and HR. The TR was significantly influenced by light intensity and distance. (4) Conclusions: Suboptimal light intensity (<800 mW/cm2) can produce inadequate polymerization at the lower side of the composite layer when used from a distance. Prolonged irradiation can improve the polymerization to a certain extent. Clinicians are advised to monitor the intensity of the LCUs in order to optimize the photopolymerization process. Caution is required when polymerizing with high-intensity curing light in direct contact with the RBC with longer exposure times than recommended. [ABSTRACT FROM AUTHOR]

In response to the typical decay and fracture defects of composite insulators, a three-dimensional electrically and thermally coupled simulation physical model was constructed based on the finite element method, and the local electric field distortion and temperature rise were analyzed. The study confirms that the insulator interface's axial electric and thermal fields show a U-shaped curve; the interface field strength is the largest. There is an electric field gradient difference between the mandrel and the sheath, and the thermal field is concentrated at the mandrel and the interface. The field strength at the edge of the defect is the largest, the aberrant electric field at the defect shows a sawtooth shape, and the temperature rise is concentrated in the defect area. The degradation is fast in the air gap, the etching hole diameter direction, and the carbonation channel axial direction. The larger the defect volume, the larger the aberration in the electric field and temperature rise. Water vapor air gaps, breakdown holes, and carbonized channels have the most pronounced electric field and temperature changes. The functional relationship between electric field aberration, temperature rise, and defect volume is established. The results provide a basis for the protection of insulator decay-like fracture. [ABSTRACT FROM AUTHOR]

The drive motor is a critical component of electric vehicles. The design of its structure, along with the regulation of temperature rises and operational control, significantly impact the overall performance of electric vehicles, affecting aspects such as dynamic response, anti-interference capabilities, speed stability, and efficiency. This paper provides a review and comprehensive analysis of the Special Issue titled "Temperature Field, Electromagnetic Field, and Operation Control of Permanent Magnet Motor for Electric Vehicles", and discusses the future development directions of permanent magnet motors in electric vehicles. The analysis reveals that the structural design is crucial for both the static and dynamic performance of permanent magnet motors. Additionally, it is imperative to identify an optimal trade-off among various performance parameters in these motors. The paper also verifies several future development directions for permanent magnet motors, including high-speed control, the use of advanced silicon steel sheets, power quality, battery charging efficiency, and energy feedback. [ABSTRACT FROM AUTHOR]

In China, high‐speed trains have become a major means of transportation for the masses. When the passengers wearing pacemakers travel on high‐speed trains, electromagnetic environment in the carriage where the GSM‐R voice and data antennae are located should be concerned. In this work, a real‐size carriage monopole antennae simulating voice and data antennae as high‐frequency radiation sources and wearing pacemaker passenger' models were established to study the electromagnetic exposure of the passenger at different conditions. The results showed that when the passenger faced the voice antenna, he suffered much greater electromagnetic radiation than when his back in turned from it. The electric field strength, average SAR, and temperature rise of the heart when facing the antenna were 27.3 V/m, 0.0102 W/kg, and 0.0016°C, respectively. Meanwhile, the temperature rise of the pacemaker was 0.001°C. We also obtained the values of electromagnetic dose for the whole body. All data were below the limits of the ICNIRP guidelines. These results indicate that the electromagnetic fields generated by the GSM‐R voice and data antennae do not harm the health of passengers wearing pacemaker. [ABSTRACT FROM AUTHOR]

In view of the large temperature rise and impact load of thrust bearings in the main shaft system of large wind turbines, this article takes the circular tilting pad thrust bearings in large wind turbines as the research object, and analyses the basic theory of bearing lubrication. The lubrication performance calculation model established for this bearing includes the Reynolds equation, energy equation, film thickness equation, and elastic deformation equation. Theoretically analysing and calculating the lubrication performance of the circular tilting pad thrust bearing, the key performance parameters have identified such as minimum film thickness (hmin), temperature rise (ΔT), power consumption (W), and flow rate (Q). The calculation results show that the eccentricity ratio has a significant impact on the lubrication performance of the circular tilting pad thrust bearing. When both radial and circumferential eccentricity ratios are around 0.5, the bearing exhibits a high temperature rise, leading to a potential risk of bearing burnout. The results also show that at a radial eccentricity ratio of approximately 0.54, the minimum film thickness reaches its maximum value of 10.34 μm. Similarly, at a circumferential eccentricity ratio of about 0.60, the minimum film thickness reaches its peak value of 21.89 μm. This indicates that the eccentricity ratio plays a crucial role in the lubrication performance. In addition, the lubrication performance of the bearing under varying loads has been calculated at a speed of 9.5 r/min. The results demonstrated that the applied load significantly impacts the thrust bearing's performance. The findings elucidate the critical role of considering the eccentricity ratio and operational external load during the bearing design process. This study validates the potential of replacing rolling bearings with sliding bearings in wind turbine main shafts. It also provides a theoretical reference for the future design of sliding bearings. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The plastic gear is widely used in agricultural equipment, electronic products, aircraft, and other fields because of its light weight, corrosion resistance, and self-lubrication ability. However, it has a limited range of working conditions due to the low modulus and thermal deformation of the material, especially in high-speed and heavy-duty situations. A compensation modification method (CMM) is proposed in this paper to restrain the heat production of the plastic gear tooth surface by considering the meshing deformation, and the corresponding modification formulas are derived. Improving the position of the maximum contact pressure (CP) and the relative sliding velocity (RSV) of the tooth surface resulted in a 30% lower steady-state temperature rise of the modified plastic gear tooth surface than that of the unmodified plastic gear. Meanwhile, the temperature rise of plastic gear with CMM is reduced by 19% compared with the traditional modification of removal material. Then, the influences of modification index and the segment number of modification on the meshing characteristics of plastic gear with CMM are discussed, such as maximum CP and steady-state temperature rise, RSV, transmission error, meshing angle, and contact ratio. A smaller segment number and modification index are beneficial to reduce the temperature rise of plastic gear with CMM. Finally, an experiment is carried out to verify the theoretical analysis model. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an important part of rotating machinery, heat generation due to friction is inevitable during the rotating process of bearings. A large amount of heat causes the temperature of lubricating oil to increase, viscosity of lubricating oil to decrease, and lubricating performance decreases. Addressing the issue of inadequate lubrication between the rolling element and raceway due to increased lubricating oil temperature, this study focuses on full-ceramic ball bearings. It examines the impact of temperature fluctuations on the bearing's lubrication condition and investigates the vibration characteristics of the full-ceramic bearing. The variation in the viscosity of lubricating oil with respect to temperature is measured via a rotary viscometer. A dynamic model of the silicon nitride full-ceramic ball bearing, which considers the effects of elastohydrodynamic lubrication, is established. The impacts of changes in lubricating oil viscosity due to different temperatures on oil film pressure, oil film thickness, and bearing vibration are analyzed and then compared with experimental data. It is observed that under conditions of constant load and speed, the film thickness of the lubricating oil decreases as the viscosity decreases. Additionally, the second peak value of oil film pressure is reduced with the declining viscosity of the lubricating oil. As the viscosity decreases, the vibration of the bearing increases. The amplitude discrepancy between the simulated vibration signal and experimental vibration signal of the full-ceramic bearing is found to be less than 10 %, verifying the validity of the dynamic model.

In order to analyze the loss, temperature rise and the mechanical structural response under the combined magnetic tension and thermal stress of the stator core, the electromagnetic-temperature-stress coupling calculation for the stator core of a synchronous generator is carried out in this paper. Firstly, the core loss and the magnetic pull per unit area are theoretically deduced, followed by an analysis of the core's temperature rise characteristics. On this basis, the mechanical structure response of the core under the coupling excitation of magnetic pull and non-uniform thermal load is obtained. Then, a three-dimensional finite element model of the CS-5 synchronous generator is established. This model calculates the magnetic pull per unit area, loss curve and temperature distribution of the stator core. Furthermore, the deformation, strain and stress of the stator core under the simultaneous action of magnetic tension and thermal load are obtained. The results show that the stator slot temperature is highest when the generator runs stably. The deformation at the groove is largest and the stress at the bottom of the groove is higher. Finally, the temperature rises of the end face, inside slot and outside circle of the stator core are monitored in real-time by thermocouples and a temperature monitor. The measured temperature distribution of the stator core is in good agreement with the finite element simulation results, verifying the effectiveness of the electromagnetic-temperature-stress coupling method. In this paper, the temperature distribution of the stator core and the mechanical structural response distribution of the stator core under magnetic and thermal coupling excitation are obtained, providing a technical reference for the reverse optimization design of the generator structure and the prevention of stator core deformation.

Direct current (DC) bias induced by the DC transmission and geomagnetically induced current is a critical factor in the abnormal operation of electrical equipment and is widely used in the field of power transmission and distribution system state evaluation. As the main affected component, the vector magnetization state of a transformer core under DC bias has rarely been studied, resulting in inaccurate transformer operation state estimations. In this paper, a dynamic vector hysteresis model that considers the impact of rotating and DC-biased fields is introduced into the numerical analysis to simulate the distribution of magnetic properties, iron loss and temperature of the transformer core model and a physical 110 kV single-phase autotransformer core. The maximum values of B, H and iron loss exist at the corners and T-joint of the core under rotating and DC-biased fields. The corresponding maximum value of the temperature increase is found in the main core limb area. The temperature rise of the 110 kV transformer core under various DC-biased conditions is measured and compared with the FEM (Finite Element Method) results of the proposed model and the model solely based on the magnetization curve B||H. The calculation error of the temperature rise obtained by the improved model is approximately 3.76–15.73% and is much less than the model solely based on magnetization curve B||H (approximately 50.71–66.92%). [ABSTRACT FROM AUTHOR]

Grinding is a prevalent metal processing method extensively employed in industrial production. However, the high temperatures generated during the grinding process can elevate the temperature of the grinding motorized spindle, subsequently impacting its performance and lifespan. Therefore, the design and research of the grinding motorized spindle cooling system become particularly important. In order to study the thermal characteristics of the grinding motorized spindle, this paper studies the two heating paths of the grinding motorized spindle based on the heat source, including the heat loss of the motor and the friction heat of the bearing, and establishes a fluid heat transfer model. Through cooling system design and thermal characteristic simulation analysis, the U-shaped cooling grinding motorized spindle is determined. The experiment found that the spindle temperature rise results are consistent with the numerical simulation results. Although the vibration amplitude will increase with the increase of the rotational speed, it will always remain within a stable range, which verifies the rationality of the cooling system design and provides ideas and methods for the design and optimization of the cooling system of the grinding motorized spindle in the future. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Power Engineering Technology is the property of Editorial Department of Electric Power Engineering Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The resistance of Arabidopsis thaliana to clubroot, a major disease of Brassicaceae caused by the obligate protist Plasmodiophora brassicae, is controlled in part by epigenetic factors. The detection of some of these epigenetic quantitative trait loci (QTLepi) has been shown to depend on experimental conditions. The aim of the present study was to assess whether and how temperature and/or soil water availability influenced both the detection and the extent of the effect of response QTLepi. The epigenetic recombinant inbred line (epiRIL) population, derived from the cross between ddm1-2 and Col-0 (partially resistant and susceptible to clubroot, respectively), was phenotyped for response to P. brassicae under four abiotic conditions including standard conditions, a 5°C temperature increase, drought, and flooding. The abiotic constraints tested had a significant impact on both the leaf growth of the epiRIL population and the outcome of the epiRIL-pathogen interaction. Linkage analysis led to the detection of a total of 31 QTLepi, 18 of which were specific to one abiotic condition and 13 common to at least two environments. EpiRIL showed significant plasticity under epigenetic control, which appeared to be specific to the traits evaluated and to the abiotic conditions. These results highlight that the environment can affect the epigenetic architecture of plant growth and immune responses and advance our understanding of the epigenetic factors underlying plasticity in response to climate change. [ABSTRACT FROM AUTHOR]

Objective There is a risk of hydrogen sulfide（H2S） leakage in the production process of high-sulfur oil and gas wells and desulfurization units in refineries, and the efficiency of emergency disposal method mainly based on physical dilution is low, which will affect the emergency rescue. A combined process of gas capture and dry desulfurization is proposed to dispose the leaked hydrogen sulfide, and whether the introduction of air in the leaked gas will affect the safety of dry desulfurization and the performance of desulfurizers is studied. Methods By simulating the dry treatment process of leaked hydrogen sulfide, the sulfur capacity and bed temperature rise of different types of dry desulfurizers such as activated carbon, iron oxide, and zinc oxide were compared and tested, and the desulfurizer with better performance was selected. Taking the optimized desulfurizer as the research object, the effects of space velocity and air content on temperature rise, penetration sulfur capacity, desulfurization accuracy, and side reactions were investigated under different H2S content. Results The 3# desulfurizer with the highest penetration sulfur capacity was selected from 8 kinds of iron oxide desulfurizers from different manufacturers. Under the simulated operating conditions of the original particle size, the penetration sulfur capacity could reach 18.2%. The rise in desulfurizer bed temperature increased with increased hydrogen sulfide content. With the increase of space velocity and air content, it increased rapidly and then tended to be stable or even slightly decreased, and the maximum temperature rise did not exceed 40 ℃. When the air volume fraction exceeded 25%, the sulfur capacity of the desulfurizer increased by about 50%, and there was a significant negative correlation between space velocity and penetration sulfur capacity. When the space velocity was lower than 1 000 h-1, the penetration sulfur capacity exceeded 25%. The desulfurization accuracy and side reactions were not affected by the air content. There was no by-product of sulfur dioxide generating before the penetration of hydrogen sulfide and at a space velocity below 2 000 h-1. Conclusions Using a dry desulfurization process to treat leaked hydrogen sulfide would result in simultaneous desulfurization and regeneration processes, with a specific temperature rise in the bed layer and no by-product of sulfur dioxide generating, which had high safety. The addition of air had a specific improvement effect on the penetration sulfur capacity of desulfurizer. When the air volume fraction was greater than 25%, and the space velocity was lower than 1 000 h-1, it was suitable for dry method emergency response of leaked hydrogen sulfide. [ABSTRACT FROM AUTHOR]

Under certain circumstances, a high-speed railway may require constant acceleration or emergency braking, in which case the inverter may experience short-term overload conditions and the current passing through the IGBT will go beyond the rated design tolerance. Under overload conditions, the IGBT loss will increase instantly, raising the power semiconductor device's junction temperature in the process. This research examines the boosting-gate-voltage-driven IGBT control technology. It increases the gate drive voltage and the IGBT current capacity and decreases the conduction voltage drop of IGBT under short-term overload conditions, reducing the instantaneous loss and temperature rise undulation of IGBT. The working characteristics of IGBT devices are studied, and the influence of gate drive voltage on device loss and temperature rise fluctuations is analyzed. Based on the emergency acceleration and brake conditions of the actual train operation, the short-term overload characteristics of the inverter are analyzed. The optimization analysis of the boosting gate voltage under emergency conditions is carried out, and the IGBT drive circuit with gate voltage pumping function is designed. The effectiveness of the driving circuit is verified through PSpice simulation and actual switching characteristic test. According to the analysis of experimental data, it can be verified that increasing the gate voltage technology can reduce IGBT losses. [ABSTRACT FROM AUTHOR]