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The shield type temporary support robot is an important component of the intelligent excavation robot system for large section roadways that adapts to the coexistence of dirt and debris. Its main function is to provide a safe and reliable workspace for achieving 'parallel excavation and support' operations. In order to enhance the safe and stable support of the shield type temporary support robot for surrounding rock during its pushing and driving process, based on the structure, working environment, and operational requirements of the shield type temporary support robot, a mathematical model of its pushing amount and support force during pressurized driving, as well as a dynamic model of pressurized driving, are established. A hydraulic control system for the shield type temporary support robot driving under pressure is designed. The system mainly consists of a support hydraulic system and a driving hydraulic system. During static support, the support hydraulic system needs to constantly output a support force greater than the weight of the upper shield body itself, and the driving hydraulic system is in standby mode. When driving under pressure, the support hydraulic system and the driving hydraulic system work simultaneously, ensuring that the temporary support robot 'reducing stress without leaving the roof' while steadily moving forward with the roof under pressure at all times. A precise control method for shield type temporary support robot driving under pressure based on fuzzy PID is proposed. The pressure and displacement signals of the temporary support robot are collected in real time by displacement sensors integrated on the displacement cylinder and pressure sensors in the hydraulic circuit. The signals are used to reflect the changes in support force and driving displacement during the temporary support robot's driving under pressure. Based on the error and error rate of the support force and displacement, the fuzzy PID algorithm is used to modify the control parameters of the support force and displacement, achieving reliable control of driving under pressure based on the fuzzy PID algorithm. Both simulation and experimental results show that the effect of fuzzy PID control is superior to traditional PID control. Under fuzzy PID control, the relative error of support force during the pushing and driving process of the shield type temporary support robot is less than 1%, and the driving displacement error is less than 2 mm. Moreover, the response speed of support force and pushing amount control is fast, ensuring the safe and stable support of the surrounding rock during the pushing and driving process.

Abstract Background A better understanding of how the prevalence of hearing loss and its associated factors change over time could help in developing an appropriate program to prevent the development of hearing loss. Methods Population-representative cross-sectional data from the United States National Health and Nutrition Examination Survey (NHANES) were used to estimate the trends in the prevalence of hearing loss among adults in the USA over the period 1999–2018. A total of 15,498 adult participants aged 20 years or older had complete audiometric examination data. Logistic regression was employed to evaluate the trend in hearing loss; weighted Rao-Scott χ2 tests and univariate logistic regression analyses were used to examine the association between hearing loss and relevant factors. Results The overall hearing loss prevalence in 1999–2018 was 19.1% 19.1 (95% CI, 18.0–20.2%). The prevalence of hearing loss decreased in cycles (P for trend 70 years the prevalence decreased from 79.9% (95% CI, 76.1–83.8%) in 2005–2006 to 64.5% (95% CI, 58.8–70.2%) in 2017–2018. Participants with hearing loss were likely to be older, male, non-Hispanic white, and to have not completed high school. Mild hearing loss was more prevalent among those aged 20–79 years; in those aged over 80 years the prevalence of moderate hearing loss exceeded that of mild loss. Among all otologically normal participants, hearing thresholds increased with age across the entire frequency range. Conclusions The prevalence of hearing loss in USA adults changed over the period 1999–2018. The trends observed provide valuable insight for making public health plans and allocating resources to hearing care. Further investigation is necessary to monitor hearing loss and its potential risk factors.

Abstract Background This study aimed to screen and validate noise-induced hearing loss (NIHL) associated single nucleotide polymorphisms (SNPs), construct genetic risk prediction models, and evaluate higher-order gene-gene, gene-environment interactions for NIHL in Chinese population. Methods First, 83 cases and 83 controls were recruited and 60 candidate SNPs were genotyped. Then SNPs with promising results were validated in another case-control study (153 cases and 252 controls). NIHL-associated SNPs were identified by logistic regression analysis, and a genetic risk model was constructed based on the genetic risk score (GRS), and classification and regression tree (CART) analysis was used to evaluate interactions among gene-gene and gene-environment. Results Six SNPs in five genes were significantly associated with NIHL risk (p

Objective: This study aimed to realize the fast and accurate sorting of citrus color. Methods: An online color detection and grading system of citrus based on machine vision was designed in this study. The system is composed of feeding unit, chain conveying mechanism, image acquisition system and fruit dividing unit. The industrial camera which was combined with the rolling mechanism was used to uniformly capture 50~60 frames of images for obtaining the complete surface information of citrus. The non-destructive testing software preprocessed each frame of images acquired in real time to obtain the two-dimensional coloring ratio, which is dynamically tracked and stored. The arithmetic mean value of two-dimensional coloring ratio was taken to reduce the influence of the repeated areas on the coloring rate calculation of citrus surface, and finally the calculated coloring rate was discriminated and graded. Results: The experimental results showed that when the transmission speed was 6 s-1, the maximum error of citrus coloring proportion calculated by the system was 5%, and the sorting accuracy rate was 90.54%. Conclusion: The system can meet the needs of fast and accurate sorting of citrus color.

Polyether imide (PEI) flat ultrafiltration membrane was prepared by immersion precipitation phase inversion method. The effects of polymer PEI concentration and additive polyvinylpyrrolidone (PVP) concentration on the structure and properties of membrane were investigated. In order to improve the solvent resistance of ultrafiltration membrane, hexamethylenediamine (HDA) was used for chemical crosslinking, and the difference of membrane performance under different crosslinking time was studied. The results show that the flux of the crosslinked membrane is effectively improved without reducing the membrane separation performance compared with the uncrosslinked ultrafiltration membrane. Under the operating pressure of 0.1 MPa, the flux of pure water is increased from 667.1 L/(m2·h) to 1126.1 L/(m2·h), while the rejection rate of 1.0 g/L BSA solution remains above 97%. After soaking in six different solvents for 48 h, it was found that the uncrosslinked membrane is completely dissolved in N, N-dimethylformamide (DMF), while the crosslinked membrane still maintains a good membrane morphology with an adsorption capacity of 0.86 g/g. The adsorption capacity in ethanol, isopropanol, n-hexane and 1 mol/L HCl solution is smaller than that of the uncrosslinked membrane, but is increased in 1 mol/L NaOH solution, which indicates that the prepared crosslinked membrane has good solvent resistance and strong acid resistance, but the strong alkali resistance becomes worse.

Block collapse or sliding is one of the main failure modes of rock slope engineering. Namely, block stability analysis plays a key role in rock slope engineering. Taking the Shenxianju rock slope in Xianju County, Zhejiang Province as the research background, this paper mainly conducts the stability analysis and visualization of rock blocks. A new method for fitting structural planes and free faces is proposed based on the linear regression method and the non-uniform rational B-spline method. Then, based on the coordinate projection method, the method for calculating the stability coefficients of the single sliding surface and double sliding surface blocks is proposed. Finally, the unmanned aerial vehicle (UAV) measurement technology combined with the coordinate projection method is used to develop a CPG program using MATLAB, which can be adopted in the stability analysis of planar polyhedron blocks and curved blocks in rock slope engineering. This program enables the spatial representation and visualization of structural planes, free faces and unstable blocks. Engineering practice shows that the new proposed method is effectively applicable to engineering geological disasters, such as rockfall and collapse. The results of the program calculation are basically consistent with those of the coordinate projection block theory, demonstrating that this method is reliable and the developed CPG program is feasible. This method is of vital significance in practical engineering since it can greatly improve the efficiency of block stability analysis.