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Due to its own structural characteristics, a harmonic drive system has a wide range of nonlinear factors, such as flexible deformation, friction and external uncertain interference. Most of the traditional controllers simplify the system to a certain extent, or do not consider the nonlinear external disturbance, resulting in that the performance of the designed controller cannot achieve the desired results. In order to improve the accuracy of the system, the dynamic model of the harmonic drive system is established considering the nonlinear stiffness and nonlinear friction of the system. Based on the test data, the parameters of the model are identified by the least square method. Radial basis function （RBF） neural network is used to approximate the nonlinear friction and external uncertain disturbance torque of the system on-line, and an adaptive inversion controller based on RBF neural network is proposed. Using Lyapunov stability theory, the convergence of the closed-loop system is proved. The simulation results show that, compared with the ordinary Back-stepping control, the proposed RBF neural network adaptive inversion control can effectively approach the system nonlinear friction and external unknown disturbance after being subjected to external unknown disturbance, and its peak value of tracking error can be quickly stabilized to 0.000 82 rad. The Back-stepping control is sensitive to external unknown interference, and the peak value of its tracking error increases to about 0.012 3 rad. The proposed RBF neural network adaptive inversion control can suppress the influence of parameter dynamic changes and external disturbances on the transmission accuracy of the system, and improve the transmission accuracy of the system.

In order to ensure the safe operation and production of oilfield gathering pipelines and to provide corrosion protection in advance,a failed oil and gas gathering pipeline in Tahe Oilfield was analyzed.The macro morphology observation of the corrosion perforation of such pipeline,the material composition analysis by direct reading spectrometer,the micro morphology observation of the sample corrosion by scanning electron microscope,the corrosion products analysis by X-ray diffractometer and energy disperse spectrometer,and the electrochemical testing were carried out to determine the cause of the perforation of the oil and gas gathering pipeline.Results showed that the highly mineralized corrosion medium,the crude oil containing a lot of CO2 and H2S,and the injected water poured into the stratum led to an CO2 corrosion inside the pipe wall.There were a lot of soluble calcium salts in the medium,and the chemical reaction between calcium salts and CO2 resulted in calcium carbonate scaling.The scaling and corrosion products were deposited on the uphill section of the pipeline,which led to serious corrosion of the metal matrix under scaling.The high-chloride ion accelerated the corrosion,and finally caused the perforation failure at the bottom of the pipeline.

The working condition of medium in the Tahe Oilfield sewage treatment system is complicated and harsh, and the forced current cathodic protection technology can effectively control the station corrosion, prolong the service life and improve the oil removal efficiency. Based on the research method of combining theory with practice and taking into account the relevant domestic and foreign standards and codes, the calculation method of the forced current parameters, the selection of the auxiliary anode block and the selection of the potentiostat were put forward from the aspects of design, construction and evaluation. The installation position and form of the auxiliary anode block were introduced, the key points and requirements of the construction quality control were summarized, and the field application of the forced current cathodic protection technology was analyzed and discussed. Besides, its applicability in Tahe Oilfield was analyzed from three levels: pre - application necessity analysis, field parameter determination and effect evaluation. It was proved that after applying the above - mentioned technology, the corrosion problem of sewage treatment system was effectively controlled, the safe and stable operation of the oil and gas processing system was ensured.

Without adding any interlayers or coatings, the lap welding experiment of AZ31B magnesium alloy and DP980 high-strength steel was performed with the laser-induced tungsten inert gas welding (TIG) arc technology. Through optimizing the process parameters, a high-quality lap weld joint was obtained. The effect of TIG arc current on the forming and mechanical properties of the joint was studied significantly. The results indicate that the wetting and spreading ability of magnesium alloy in high-strength steel is improved with the increase of arc current, which increases the weld width and reduces the wetting angle. Additionally, the maximum tensile load of magnesium alloy/steel welded joints increases first and then decreases with the increase of arc current and the fracture mode of the joint is changed from fracture along the interface to fracture along the weld. When the TIG current is 80 A and the laser power is 350 W, the maximum average tensile load of the welded joint reaches 279 N/mm.The increase of weld width, thickness of interfacial layer and pinning of laser keyholes together enhance the performance of magnesium alloy/steel joints.

Objective To explore the application effect of continuous quality improvement (CQI) in promoting regional cooperation and development of district-level Central Sterile Supply Department (CSSD). Methods The CQI program had been carried out based on the cooperative development of district-level Central Sterile Supply Department science 2020. The quality of cleaning and disinfection of medical apparatus package collected from district-level CSSD was evaluated before and after implementation of CQI. The knowledge level and satisfaction of nursing staff from district-level CSSD were assessed. Results The rates of qualified preprocessing, cleaning, packaging and storage in CSSD after implementation of CQI were higher than those before implementation of CQI(P＜0. 01). The rate of CSSD-related knowledge mastery and total satisfaction rate after the implementation of CQI were higher than those before implementation of CQI (P＜0. 01). Conclusion The application of CQI in the management of district-level Central Sterile Supply Department can ensure the quality of equipment cleaning and sterilization, improve the work efficiency and the overall level of infection prevention and control of medical institutions in the region. (目的 探讨持续质量改进(CQI)在促进区级消毒供应中心区域合作发展的应用效果。方法 2020年度基于医院的区域化消毒供应中心实施CQI管理。分别于CQI实施前和实施后抽取各合作基层医疗机构送至医院消毒供应中心再处理物品240件, 比较2019年1月—12月(实施前)及2020年1月—12月(实施后)消毒供应中心器械管理质量, 评价区域化消毒供应涉及医护人员消毒供应理论水平和满意度情况。结果 CQI实施后消毒供应中心器械预处理合格率、清洗合格率、包装合格率、存储合格率均高于实施前, 差异有统计学意义(P＜0. 01)。CQI实施后医护人员对消毒供应理论知识及流程掌握度及满意度均较CQI实施前提升, 差异有统计学意义(P＜0. 01)。结论 在区级消毒供应中心管理中应用CQI, 可以确保器械清洗、灭菌质量, 提高工作效率, 整体提升区域内医疗机构感染防控水平, 确保患者安全。)

Objective To investigate the risk factors of vestibular schwannoma without facial nerve functional preservation. Methods Total 95 patients with vestibular schwannoma who underwent surgery via the sigmoid sinus approach bewteen December 2018 to January 2020 were included. Tumor diameter and classification, tumor volume and surface area, tumor property were recorded according to MRI. The course of facial nerve, adhesion degree between tumor and facial nerve, extent of tumor resection and facial nerve anatomic preservation were recorded according to intraoperative observation. Facial nerve function after 8 d was evaluated. Univariate and multivariate Logistic regression analyses were performed to analyze risk factors associated without facial nerve functional preservation. Results Of the 95 patients, 80 patients (84.21%) underwent gross total resection, among which 3 patients had no anatomical preservation of facial nerve. 15 patients (15.79%) underwent near total resection, including 14 cases with thin layer of tumor remaining on the facial nerve, and one case with thin layer of tumor remaining on the brainstem and no anatomical preservation of facial nerve. Logistic regression analysis showed that severe adhesion between tumor and facial nerve was risk factor for functional impairment of facial nerve (OR = 22.349, 95%CI: 1.895-263.599; P = 0.014). Conclusions For severe adhesion, the operation should be more careful. If the tumor might not be completely removed under the premise of preserving the facial nerve function, a small amount of tumor could be left on the facial nerve.

The aims of this study were to a) quantify the relationships between sprinting and dribbling speed measured using dribble time and Dribble Deficit and b) assess the difference between age categories in sprinting and dribbling speed in pre-adolescent basketball players. Pre-adolescent, male basketball players (Total, N = 81; Under-10, n = 32, Under-9, n = 49) completed two trials of different tasks including 20-m linear sprints without dribbling, 20-m linear sprints dribbling with dominant and non-dominant hands, and change-of-direction (COD) sprints with and without dribbling. Sprinting time, dribbling time and Dribble Deficit were then calculated for each trial. Spearman rank correlations were used to assess the relationships between outcome measures for Under-9 and Under-10 players separately and combined. The Mann-Whitney U test with effect sizes (ES) was used to assess differences in outcome measures between Under-9 and Under-10 players. Moderate-to-very large significant relationships (p

To reveal the regularity of arsenic adsorption of sediment, this study explores the law of arsenic adsorption by sediment when Fe3+ and Mn2+ coexist. The experimental results fit the first-order kinetic model and the second-order kinetic model. The surface physicochemical properties of sediment particles were analysed by scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherm and fractal dimension. Characterization of surface area and pore distribution were measured by the BET equation and BJH equation. The results illustrate that the adsorption of arsenic by sediment shows the phenomenon of rapid adsorption in the early stage, slow adsorption in the middle stage and finally adsorption equilibrium. In the presence of coexisting ions, the BET specific surface area was as high as 20.14m2/g, the pore volume as 0.047826cm3/g, the surface pore volume as 43.25cm3, and the surface fractal dimension Ds as the largest.

Aiming at the problem that the coal bodies of the two sides of the roadway were loosened and destroyed to cause the coal body to be compressed and the deformation of the roof and the two sides during the advancing process of roadway 43222 in the fourth panel area of Changping Coal Mine. Through the analysis of the grouting reinforcement mechanism of the surrounding rock of the roadway, as well as the simulation study of the disturbance of the working face of the 43222 roadway, the grouting parameters are finally determined and the grouting scheme is given. The on-site monitoring results show that the grout fully enters the joints and fissures after the grouting is completed, filling the broken areas, and the roadway deformation is controlled, the roof sinking amount is stable at 80 mm, the floor heave amount is stable at 63 mm, and the two-side approaching amount is stable at 110 mm. The overall stability of the surrounding rock has been improved, which effectively solves the difficulty problem of leaving soft and broken coal roadways, and meets the demand for continued use of the next working face.

Based on the theoretical approaches to interlanguage and discourse cohesiveness, this study examines international students' growth in discourse awareness and discourse competence in the teaching of elementary Chinese reading and writing, and explores a set of assessment methods for teaching discourse. The learners' knowledge and production of Chinese conjunctive words were assessed with multiple test methods, including the sentence sequencing test for testing learners' cognitive understanding of discourse cohesiveness, the elicitation tasks for assessing learners' production of conjunctive words, the tests of picture-based sentence writing and essay writing for evaluating learners' discourse awareness of the cohesiveness in form and meaning. 13 students were recruited by us to participate in these tests. A comprehensive discussion of the data supports that appropriate reading and writing instruction can develop learners' discourse competence and enhance their discourse awareness to a certain extent.

This study investigates the capacity of elementary-level Chinese second language learners to memorize serial verb sentences based on the results of a questionnaire. Our findings show that adult second language learners employ the concept of temporal sequence in language learning, consciously or unconsciously, whether or not the chronological principle has been formally taught. Therefore, we propose that specific cognitive principles, such as the chronological principle, should be carefully applied or formally taught in language training to maximize teaching and learning effectiveness.

A high intensity D-T fusion neutron generator (HINEG) is keenly needed for the research and development (R&D) of nuclear technology and safety of the advanced nuclear energy system, especially for the radiation protection and shielding. The R&D of HINEG includes two phases: HINEG-I and HINEG-II. HINEG-I is designed to have both the steady beam and pulsed beam. The neutron yield of the steady beam is up to 1012 n/s. The width of pulse neutron beam is less than 1.5 ns. HINEG-I is used for the basic neutronics study, such as measurement of nuclear data, validation of neutronics methods and software, validation of radiation protection and so on. HINEG-II aims to generate a high neutron yield of 1013 n/s neutrons by adopting high speed rotating tritium target system integrated with jet/spray array enhanced cooling techniques, and can further upgrade to obtain neutron yield of 1014~1015n/s by using of accelerators-array in a later stage. HINEG-II can be used for fundamentals research of nuclear technology including mechanism of materials radiation damage and neutronics performance of components, radiation shielding as well as other nuclear technology applications.

In Supplementary Table 1 of this Article, 23 samples (B10K-DU-029-32, B10K-DU-029-33, B10K-DU-029-36 to B10K-DU-029-44, B10K-DU- 029-46, B10K-DU-029-47, B10K-DU-029-49 to B10K-DU-029-53, B10K-DU- 029-75 to B10K-DU-029-77, B10K-DU-029-80, and B10K-DU-030-03; styled in boldface in the revised table) were assigned to the incorrect institution. Supplementary Table 1 has been amended to reflect the correct source institution for these samples, and associated data (tissue, museum ID/source specimen ID, site, state/province, latitude, longitude, date collected and sex) have been updated accordingly. The original table is provided as Supplementary Information to this Amendment, and the original Article has been corrected online.