Explore the vast range of titles available.

Aluminum-based silicon carbide (SiCp/Al) is a hard-to-process material. SiC particles are randomly distributed and have a unique structure, thus posing challenges during processing. These distinctions considerably affect the overall quality of machining. As the volume fraction increases, the machinability continues to decline. Understanding the removal mechanism of SiCp/Al composites is essential for improving their machined surface quality. This study explores the influence of vibration frequency on the removal mechanism and plastic deformation in high-volume fraction SiCp/Al composites using non-resonant vibration-assisted scratching (NVAS) experiments combined with molecular dynamics (MD) simulations. The experimental results show that compared with conventional scraping (CS), increasing the vibration frequency in the NVAS process significantly expands the plastic removal area and reduces the scraping force. The simulation results indicate that as vibration frequency rises, the smoothness of the scratched groove improves, leading to a more uniform distribution of dislocations and a significant reduction in dislocation loops and HCP structures, promoting plastic deformation of the material. The simulation explains and clarifies the occurrence of plastic deformation observed during the scratching experiments. This study can provide a potential understanding of non-resonant vibration-assisted high-volume SiCp/Al composites machining.

In the contemporary post-truth era, there is a marked increase in the individual’s need for emotional expression and self-awareness. This paper introduces and defines the concept of “Fetish Opposition” through etymological research. Employing fault tree analysis, this study analyzes the risk identification and structural importance of “Fetish Opposition” in the context of “Public Security Prohibition” enforced by police departments. This is approached from the perspective of security system engineering, aiming to elucidate the underlying issues and delineate strategies to mitigate the phenomenon of “anti-public security.” This exploration seeks to provide theoretical guidance for enhancing the effectiveness of public security organs. The findings indicate that “lack of law enforcement transparency” holds structural importance of 0.186 within the fault tree of “Fetish Opposition,” making it the most significant factor affecting the entire system. Based on this insight, the police public relations department could develop targeted strategies to prevent such situations, thereby also opening new avenues for research in social psychology and the stabilization of police-community relations.

The diffraction refers to the phenomenon that when light encounters an obstacle during propagation, it will deviate from the original propagation path and propagate behind the obstacle. In the study of diffraction and the relevant, we often encounter the questions about the prediction or estimation on the diffraction patterns of apertures with various shapes. Yet the specially designed optical experiment is very time consuming and laborious for this simple purpose. In this paper, the laser far-field diffraction is studied based on Kirchhoff diffraction theory. The intensity distribution is described by using a two-dimensional matrix and then the mathematical representations of the diffraction pattern of arbitrary aperture are provided. Visualization of calculated data is achieved by computer programming, and high-precision diffraction patterns are obtained. The above theoretical analysis method presented in this paper has higher universality. When the calculation infinitesimals are small enough and the computer graphics display function is sufficient, the diffraction pattern with high resolution can be obtained efficiently compared with the experiment.

5G positioning technology has become deeply integrated into daily life. However, in wireless signal propagation environments, there may exist non-line-of-sight (NLOS) conditions, which lead to signal blockage and subsequently hinder the provision of positioning services. To address this issue, this paper proposes an intelligent reflecting surface (IRS) NLOS time difference of arrival–angle of arrival (TDOA-AOA) localization (INTAL) algorithm. First, the algorithm constructs a system model for 5G IRS localization, effectively overcoming the challenges of positioning in NLOS paths. Then, by applying the multiple signal classification algorithm to estimate the time delay and angle, and using the Chan algorithm to obtain the user’s estimated coordinates, an optimization problem is formulated to minimize the distance between the estimated and actual coordinates. The tent–snake optimization algorithm is employed to solve this optimization problem, thereby reducing localization errors. Finally, simulations demonstrate that the INTAL algorithm outperforms the snake optimization (SO) algorithm and the gray wolf optimization (GWO) algorithm under the same conditions, reducing the localization error by 56% and 60% on average, respectively. Additionally, when the signal-to-noise ratio is 30 dB, the localization error of the INTAL algorithm is only 0.2968 m, while the errors for the SO and GWO algorithms are 0.6733 m and 0.7398 m, respectively. This further proves the significant improvement of the algorithm in terms of localization accuracy.

Unmanned aerial vehicle laser scanning (UAVLS) systems present a relatively new means of remote sensing and are increasingly applied in the field of forest ecology and management. However, one of the most essential parameters in forest inventory, tree diameter at breast height (DBH), cannot be directly extracted from aerial point cloud data due to the limitations of scanning angle and canopy obstruction. Therefore, in this study DBH-UAVLS point cloud estimation models were established using a generalized nonlinear mixed-effects (NLME) model. The experiments were conducted using Larix olgensis as the subject species, and a total of 8364 correctly delineated trees from UAVLS data within 118 plots across 11 sites were used for DBH modeling. Both tree- and plot-level metrics were obtained using light detection and ranging (LiDAR) and were used as the models’ independent predictors. The results indicated that the addition of site-level random effects significantly improved the model fitting. Compared with nonparametric modeling approaches (random forest and k-nearest neighbors) and uni- or multivariable weighted nonlinear least square regression through leave-one-site-out cross-validation, the NLME model with local calibration achieved the lowest root mean square error (RMSE) values (1.94 cm) and the most stable prediction across different sites. Using the site in a random-effects model improved the transferability of LiDAR-based DBH estimation. The best linear unbiased predictor (BLUP), used to conduct local model calibration, led to an improvement in the models’ performance as the number of field measurements increased. The research provides a baseline for unmanned aerial vehicle (UAV) small-scale forest inventories and might be a reasonable alternative for operational forestry.

Objective This study aims to translate and validate the CarerQol in a sample of informal caregivers in China. Method The CarerQol was translated following a standard process. Validation data was collected from multiple sources, including hospitals, patient associations, and community health centers between September 2023 and December 2024 in China. Caregivers of individuals with disability or long-term care needs were recruited. The psychometric properties of the CarerQol-7D were evaluated through ceiling and floor effects, factorial structure, convergent and divergent validity, known-groups validity, and test-retest reliability. Results A total of 324 participants completed the survey and provided validated responses. The mean CarerQol level sum score was 12.8 (SD = 2.9). The CarerQol-7D showed no ceiling or floor effects at either dimension or scale levels. Test-retest reliability of the CarerQol-7D was satisfactory, as supported by ICC and Gwet’s AC1 measures. Correlation analysis confirmed all hypothesized pairs of dimensions and level sum scores/utility scores between CarerQol-7D, SF-6Dv2, and ICECAP-A. The CarerQol-7D successfully distinguished between risk groups through ANOVA testing. Confirmatory factor analysis revealed that a one-factor model of the CarerQol-7D fit the data. Conclusion This study provides the Chinese version of the CarerQol and confirms its sound psychometric properties for informal caregivers in China. These findings demonstrate the CarerQol’s value in cost-effectiveness analyses of caregiving interventions and strategies.

Background Occupational hazards occur in all walks of life. China’s horticulture industry is undergoing rapid development. However, the mental health of garden workers has not received much attention. This study investigates the mental health status and influencing factors of Chinese garden workers and provides a basis for promoting their mental health and ensuring the healthy development of Chinese horticulture. Methods A cross-sectional survey of garden workers in Beijing was conducted from 10 July 2021 to 10 October 2021. A total of 3349 valid questionnaires were recovered, with an effective response rate of 95.69%. Descriptive statistical analysis was carried out on the demographic characteristics, job satisfaction, stress, anxiety, and depression of garden workers, and the influencing factors affecting the mental health of Chinese garden workers were found through a t-test, variance analysis, and ordinal multi-class logistic regression analysis. Results Survey respondents were mostly male (54.4%) and under the age of 40 (64.1%). The anxiety and depression symptoms of the garden workers were moderate. Among staff members, 40.2% were in a normal state of stress. Gender, three meals on time, monthly income, and job satisfaction were the factors influencing stress, anxiety, and depression symptoms among garden workers. Conclusion Compared to medical staff and other groups, the stress, anxiety, and depression symptoms of Chinese garden workers are severe. Gender, monthly income, and job satisfaction are important factors affecting their mental health. Managers should continuously improve the working environment of garden workers, provide salaries that match their positions, and improve their job recognition and satisfaction to reduce the impact of negative emotions on personal health.

As a core content of forest management, the height to crown base (HCB) model can provide a theoretical basis for the study of forest growth and yield. In this study, 8364 trees of Larix olgensis within 118 sample plots from 11 sites were measured to establish a two-level nonlinear mixed effect (NLME) HCB model. All predictors were derived from an unmanned aerial vehicle light detection and ranging (UAV-LiDAR) laser scanning system, which is reliable for extensive forest measurement. The effects of the different individual trees, stand factors, and their combinations on the HCB were analyzed, and the leave-one-site-out cross-validation was utilized for model validation. The results showed that the NLME model significantly improved the prediction accuracy compared to the base model, with a mean absolute error and relative mean absolute error of 0.89% and 9.71%, respectively. In addition, both site-level and plot-level sampling strategies were simulated for NLME model calibration. According to different prediction scale and accuracy requirements, selecting 15 trees randomly per site or selecting the three largest trees and three medium-size trees per plot was considered the most favorable option, especially when both investigations cost and the model’s accuracy are primarily considered. The newly established HCB model will provide valuable tools to effectively utilize the UAV-LiDAR data for facilitating decision making in larch plantations management.

This study investigates the displacement behavior of excavations under asymmetric loading conditions and proposes optimized support design strategies from the perspective of displacement control. Physical model tests reveal that, in excavation projects under eccentric loading conditions, the retaining structure as a whole tends to deform toward the non-surcharge side rather than following the conventional symmetric deformation pattern. Displacement increases nonlinearly with surcharge intensity, but the growth rate diminishes as the load further increases due to localized surcharge effects and structural restraints. Numerical analyses further demonstrate that increasing embedment depth and wall thickness effectively mitigates lateral displacement, although a marginal effect is observed beyond critical thresholds. For instance, at an embedment depth of 12 m (twice the excavation depth), maximum lateral displacement decreases by nearly 50%, and when combined with a wall thickness of 13 cm and a depth of 14 m, the reduction reaches approximately 90%. These findings establish a quantitative basis for deformation control in excavations subjected to asymmetric loading and guide the efficient optimization of retaining systems. They enhance design reliability and construction efficiency, offering practical value for improving safety, performance, and overall project economy.

Background The family doctor system has developed rapidly all over the world, and in the past few years, China has actively explored family doctor-type contracted services. This study aimed to explore the related factors of Contracted Family Doctors Services (CFDS) from the perspectives of medical staff and consumers, and to provide a stronger basis for the development and promotion of CFDS. Methods A combination of quantitative and qualitative methods were used in this study. A self-reported questionnaire was designed through a literature analysis, group discussions, expert consultations and a pre-investigation, and conducted among community health service providers in 12 community health service centres across four provinces of China. A total of 389 participants participated, and 320 valid questionnaires were obtained, with an effective response rate of 82.3%. A total of 36 consumers participated in in-depth interviews, and the effective rate was 100.0%. An exploratory factor analysis, a confirmatory factor analysis, inductive methods, and expert consultations were used to analyse the related factors of CFDS. Results The related factors of CFDS from the perspectives of medical staff were divided into four dimensions, with the following weighting coefficients: national government factors (31.9%), community health service agency factors (24.7%), consumer-related factors (22.6%), and contracted doctor-related factors (20.8%). The related factors of CFDS from the perspectives of consumers were divided into four dimensions, with the following frequency sequence: national government factors, contract doctor-related factors, community health service agency factors, and consumers-related factors. National government factors played an important role in CFDS from the perspectives of medical staff and consumers. Conclusions The related factors of CFDS were the same from the perspective of medical staff and consumers, but the weight of each factor was different. The development of CFDS is inseparable from the support of policies. It is suggested that the government should strengthen the publicity of CFDS, expand the coverage, introduce personalised contract programs that meet the needs of different groups, and promote the rapid development of CFDS.