Abstract: Aiming at the problem of steel surface defects, a defect detection algorithm based on YOLOv8 is constructed. Firstly, SimAM is added to the head to improve the expression ability of the features to enhance the detection ability of the model for tiny defects or small targets. Then the CIoU loss function is replaced with Wise-IoU to enhance the detection accuracy of the model. The experimental results show that the constructed improved models P, mAP0.5 and mAP0.5:0.95 reach 74.6%, 75.6% and 43.4%, respectively, which are improved by 5.9%, 0.5% and 0.6%, respectively, compared with the original YOLOv8n model. The detection accuracy was effectively improved. Read More

Abstract: As one of the most important dynamic excitation sources, the gear time-varying mesh stiffness is the key parameter of gear system dynamic model. So how to calculate the gear mesh stiffness accurately is of great importance. Based on Euler beam theory, this paper proposes a primitive calculation algorithm (PCA) to calculate the time-varying mesh stiffness of spur gears. A simplified gear model is developed based on nonlinear strain-displacement relationships, and a finite element program is used to simulate the gear's meshing stiffness. The rationality of this method was verified through finite element analysis. The results indicate that mesh stiffness plays a crucial role in controlling mesh deformation. In view of this, this study lays a theoretical foundation for further analysis of the vibration and noise of gears. Read More

Abstract: Gear systems are subjected to repeated loads during long-term operation, and factors such as insufficient lubricant to increase friction between gears, resulting in elevated temperatures and wear, are highly susceptible to tooth spalling. Tooth spalling is a common form of failure in gear failure. In previous studies, the vibration response of a gear pair with spalling defects at the tooth center near the pitch circle has been investigated. However, the location of the spalling defects offset from the center of the tooth flank is rarely studied. Tooth spalling faults occur in the pitch circle, but not necessarily in the center of the tooth, often formed on both sides of the center of the tooth and torsion in the meshing process. the symmetric and asymmetric rectangular spalling defects are considered, the torsional deformation is introduced. “torsional stiffness” is introduced into the overall TVMS due to the spalling defect. Therefore, it is meaningful to grasp the reasons for the formation of tooth spalling. Read More

Abstract: The design of the PCTC cargo compartment ventilation system is an important system in the overall PCTC ship design, which is related to the design of multiple specialties such as general, structure, outfitting, machinery and electrical section. In recent years, the design of the cargo hold ventilation system for PCTC ships has also been constantly changing, improving, and optimizing. This article summarizes and optimizes the current mainstream design schemes for the electrical system of PCTC cargo hold ventilation, taking into account both the construction cost of the shipyard and the operating cost of the shipowner, for reference by relevant designers. Read More

Abstract: This study investigates the crushing strength of single diamond grains of varying grades and particle sizes using the WDW-100 electronic universal testing machine. The research aims to understand the mechanical properties of diamond particles, which are critical for optimizing the performance of diamond tools in industrial grinding processes. High-grade diamond particles, characterized by their regular polyhedral shapes and minimal impurities, exhibit higher and more stable maximum load forces compared to medium- and low-grade particles. Medium-grade particles show a balance between strength and brittleness, while low-grade particles display significant variability in their structural integrity due to higher impurity levels and defects. The study also reveals that larger diamond particles tend to have lower average maximum load forces, attributed to increased crystal defects and pronounced grain boundary effects. These findings underscore the importance of considering both the grade and particle size of diamond grains in applications requiring high mechanical strength. The insights gained from this research are essential for improving the design and durability of diamond tools, ensuring their efficiency and longevity in industrial applications. Read More

Abstract: In order to solve the problem of low rock carrying efficiency of coring drilling tools in the process of coring operation under extreme ultra-high temperature and high-pressure environment, and considering the key rock carrying parameters such as coring bit type, cuttings particle size, drilling speed and drilling fluid viscosity in different formations, the three-dimensional model and flow field coupling model of coring tools with different specifications are established. The finite element method is used to evaluate the rock carrying capacity of the annulus of the coring outer cylinder. The results show that for the same type of coring tools, reducing the particle size of cuttings, increasing the viscosity of drilling fluid and reducing the drilling speed can reduce the volume fraction of residual cuttings and improve the rock carrying capacity of coring tools. For the 121,140,172 type coring tools, when the two drilling speeds are 0.8 m/h and 2.1 m/h respectively, the rock carrying capacity gap decreases with the increase of cuttings particle size. When the two drilling speeds of 203 type coring tools are 0.8m/h and 2.1m/h respectively, the difference of rock carrying capacity increases with the increase of cuttings size. Read More

Abstract: Roadbed construction occupies a core position in highway construction, but its quality is easily constrained by multiple factors such as changing environmental factors, the performance of construction equipment, and the professional abilities of construction personnel, leading to potential quality risks. Traditional quality inspection methods are mostly carried out after construction is completed, making it difficult to achieve continuous and real-time monitoring of roadbed compaction quality, which to some extent limits the real-time feedback and adjustment of construction quality. Vibration compaction technology has been widely used in the field of highway engineering due to its high efficiency and speed. The compaction degree is directly related to the durability and service life of the highway; therefore, accurate and efficient detection of compaction degree is crucial. This article proposes a method for detecting roadbed compaction degree by integrating machine learning (ML) and vibration acceleration signals. This method aims to achieve accurate evaluation of roadbed compaction by real-time monitoring and analysis of vibration acceleration data, combined with the powerful prediction and classification capabilities of ML algorithms. The experimental results show that this method not only improves the detection efficiency, but also significantly enhances the accuracy of compaction degree detection. Read More

Abstract: Research on Luminescent Solar Concentrators (LSCs) is crucial for enhancing the energy density of sunlight and lowering the costs associated with silicon solar cells. This paper thoroughly evaluates and compares the performance of three different LSC materials: Rhodamine B (RBB), Rhodamine 6G (R6G), and Coumarin 6 (C6). The study focuses on several key metrics, including Stokes shift, external quantum efficiency, concentration factor, and conversion factor. By analyzing these parameters, the paper aims to elucidate how each material's properties influence overall performance, providing valuable insights into optimizing LSC design for improved energy harvesting. In order to pave the way for more widespread adoption of LSCs in solar applications, enhancing their role in sustainable energy systems. Read More

Abstract: To enhance the reliability of new energy grid connected systems, a fault-tolerant model predictive control strategy with low-voltage ride-through capability for grid connected inverter bridge arms has been proposed. Firstly, the operational principles following a single-phase bridge arm fault in the grid-tied inverter are analyzed. Then, a fault-tolerant structure for the grid connected inverter is established by creating a virtual bridge arm using direct current-side capacitors. Subsequently, a current prediction model is established, and control is implemented using redundant vectors. Additionally, by dynamically adjusting reactive current compensation commands based on the relationship between grid voltage drops and reactive current commands, the system is ensured to maintain continuous and stable operation even during grid voltage fluctuations. Finally, experimental results demonstrate that this fault-tolerant control strategy can still maintain the continuous and stable operation of the system when bridge arm faults occur due to grid voltage drops at the inverter grid connection point. Read More

Abstract: This paper addresses the chatter problem in thin-walled part milling, reviewing the advancements in mirror milling technology for thin-walled parts. It provides an in-depth discussion of the fundamental causes of chatter during thin-walled part milling. A comparative analysis of the advantages and disadvantages of empirical, finite element, and analytical models for milling force in thin-walled parts is presented. The paper also discusses the experimental methods, finite element modal analysis, and structural coupling methods used to obtain the frequency response functions of workpieces and tools, comparing their respective strengths and weaknesses. Furthermore, time-domain and frequency-domain methods for stability prediction are analyzed and compared, with a discussion on the future prospects of chatter stability prediction in mirror milling. Read More

Abstract: Ethnic minority clothing refers to clothing with unique characteristics of ethnic minorities. Ethnic minorities have rich clothing culture and living habits, and their production techniques are diverse and unique. As traditional handicrafts, with the development of modern society, some traditional handicrafts face severe inheritance problems. Therefore, it is urgent to protect them and they have historical responsibilities. Of course, the value of inheritance is immeasurable. In this article, I take the characteristics of ethnic minority clothing as the starting point and propose specific protection and inheritance strategies, aiming to provide some valuable reference suggestions for the protection and inheritance of ethnic minority clothing. Read More

Abstract: This study employed a correlational research method to examine the relationship between coaches’ self-efficacy – specifically in terms of emotion, optimism, work satisfaction and self-confidence -and athletes’ self-efficacy, which includes personality self- efficacy, sports discipline, psychological self-efficacy and professional thought efficacy. A purposive sampling technique was used to specifically select 10 badminton coaches. Meanwhile, stratified sampling was employed to proportionately distribute the 300 athletes from five universities, ensuring representation from different subgroups. This study found no significant correlation between coaches’ self-efficacy and athletes’ self-efficacy as indicated by the p values greatre than the .05 level of significance set in the study. Despite the Spearman rho coefficients ranging from moderate to high, these results were not statistically significant, these findings suggest that while there may be observable trends the relationship between coaches and athletes’ self-efficacy is not conclusively supported by the data. Read More

Abstract: Today, Chinas ceramic industry is mainly divided into two parts, one is a creative studio and a small characteristic factory, the other is a large daily ceramic industry and an enterprise that can represent the industry. This paper combs these two pieces from the ancient and modern time line, Chinese and foreign space line supplemented by cases to do some production and development of daily ceramics. By paying attention to the reasons for the rise of foreign ceramic brands, and then looking back at the shortcomings of their own brands, in order to understand and summarize the advantages and weaknesses of the development of ancient and modern daily ceramic industry in Chinese and foreign countries, self-innovation, deepen the core, reshaping the continuation of the glorious history of more than 2000 years and the world image of Chinese ceramics. Read More

Abstract: The 14th Five-Year Plan period is a period for my country to further promote the high-quality and high-efficiency development of "technology, fashion, and green". The training direction of college graduates is constantly changing, and school-enterprise cooperation is constantly subdivided and deepened. As a result, college evaluation is also linked to the employment rate of graduates. It is more required that the graduates trained by the school transform into market-oriented application talents. Therefore, following the three basic principles of highlighting student-centeredness, output orientation, and continuous improvement, introducing the concept of corporate brand show in graduation design to carry out school-enterprise linkage and integrated teaching has become an important task that the fashion design major must face, innovate and explore. Read More

Abstract: Dynamical models for super gear systems have been established, considering both fixed gear backlash and time-varying gear backlash. The focus is on analyzing the modeling process of the time-varying gear backlash. Based on this, a six degrees of freedom bending-twisting dynamical model for super gears has been developed. Then, using rotational speed as the control variable, numerical simulations have been conducted to compare the bifurcation characteristics of super gear systems with fixed gear backlash and time-varying gear backlash. The results indicate that the overall trends of the bifurcation characteristics for both systems are consistent, with their vibration periods decreasing as the rotational speed increases, leading to a gradual stabilization of the system. However, the bifurcation characteristics of the super gear system considering the time-varying gear backlash exhibit a distinct leading trend, showing significant jump phenomena at relatively low rotational speeds. Read More

Abstract: The use of high contact ratio (HCR) gears is an effective method to reduce single tooth loads, as well as vibration and noise, making the application of helical gears increasingly widespread. Although the presence of helix angles can cause significant relative sliding, the presence of more teeth in contact makes HCR gears more sensitive to surface quality. The existing literature mainly investigates geometric optimization, load distribution, or efficiency calculation of helical gears. The research on the influence of rough surfaces on the dynamic performance of helical gears is very limited. To this end, a multi degree of freedom mathematical model of static transmission error was established based on the 2-DOF system. The relative sliding friction was studied using different friction coefficients, and the influence of different friction coefficients on the gear system was analyzed in detail. The numerical results indicate that surface roughness has a relatively small impact on the dynamic transmission error of the system, but has a significant impact on the motion and friction in the direction of departure. Read More