Design and optimization of fluid lubricated bearings operated with extreme working performances——a comprehensive review

Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.

A Review on Technologies for the Use of CO2 as a Working Fluid in Refrigeration and Power Cycles

The use of carbon dioxide as a working fluid has been the subject of extensive studies in recent years, particularly in the field of refrigeration where it is at the heart of research to replace CFC and HCFC. Its thermodynamic properties make it a fluid of choice in the efficient use of energy at low and medium temperatures in engine cycles. However, the performance of transcritical CO2 cycles weakens under high temperature and pressure conditions, especially in refrigeration systems;On the other hand, this disadvantage becomes rather interesting in engine cycles where CO2 can be used as an alternative to the organic working fluid in small and medium-sized electrical systems for low quality or waste heat sources. In order to improve the performance of systems operating with CO2 in the field of refrigeration and electricity production, research has made it possible to develop several concepts, of which this article deals with a review of the state of the art, followed by analyzes in-depth and critical of the various developments to the most recent modifications in these fields. Detailed discussions on the performance and technical characteristics of the different evolutions are also highlighted as well as the factors affecting the overall performance of the systems studied. Finally, perspectives on the future development of the use of CO2 in these different cycles are presented.

Relationship between physical activity and specific working memory indicators of depressive symptoms in university students

BACKGROUND The detection rate of depression among university students has been increasing in recent years,becoming one of the main psychological diseases that endangers their physical and mental health.According to statistics,self-harm and suicide,for which there is no effective intervention,are the second leading causes of death.AIM To explore the relationship between different elements and levels of physical activity and college students’depression-symptom-specific working memory indicators.METHODS Of 143 college students were analyzed using the Beck Depression Self-Rating Scale,the Physical Activity Rating Scale,and the Working Memory Task.RESULTS There was a significant difference between college students with depressive symptoms and healthy college students in completing verbal and spatial working memory(SWM)tasks correctly(all P<0.01).Physical Activity Scale-3 scores were significantly and positively correlated with the correct rate of the verbal working memory task(r=0.166)and the correct rate of the SWM task(r=0.210)(all P<0.05).There were significant differences in the correct rates of verbal and SWM tasks according to different exercise intensities(all P<0.05)and different exercise durations(all P<0.05),and no significant differences in the correct rates of verbal and SWM tasks by exercise frequency(all P>0.05).CONCLUSION An increase in physical exercise among college students,particularly medium-and high-intensity exercise and exercise of 30 min or more,can improve the correct rate of completing working memory tasks.

Working condition recognition of sucker rod pumping system based on 4-segment time-frequency signature matrix and deep learning

High-precision and real-time diagnosis of sucker rod pumping system(SRPS)is important for quickly mastering oil well operations.Deep learning-based method for classifying the dynamometer card(DC)of oil wells is an efficient diagnosis method.However,the input of the DC as a two-dimensional image into the deep learning framework suffers from low feature utilization and high computational effort.Additionally,different SRPSs in an oil field have various system parameters,and the same SRPS generates different DCs at different moments.Thus,there is heterogeneity in field data,which can dramatically impair the diagnostic accuracy.To solve the above problems,a working condition recognition method based on 4-segment time-frequency signature matrix(4S-TFSM)and deep learning is presented in this paper.First,the 4-segment time-frequency signature(4S-TFS)method that can reduce the computing power requirements is proposed for feature extraction of DC data.Subsequently,the 4S-TFSM is constructed by relative normalization and matrix calculation to synthesize the features of multiple data and solve the problem of data heterogeneity.Finally,a convolutional neural network(CNN),one of the deep learning frameworks,is used to determine the functioning conditions based on the 4S-TFSM.Experiments on field data verify that the proposed diagnostic method based on 4S-TFSM and CNN(4S-TFSM-CNN)can significantly improve the accuracy of working condition recognition with lower computational cost.To the best of our knowledge,this is the first work to discuss the effect of data heterogeneity on the working condition recognition performance of SRPS.

Positive Effect of Transcranial Direct Current Stimulation on Visual Verbal Working Memory in Patients with Attention-Deficit/Hyperactivity Disorder

Background: Working memory is an executive function that plays an important role in many aspects of daily life, and its impairment in patients with attention-deficit/hyperactivity disorder (ADHD) affects quality of life. The dorsolateral prefrontal cortex (DLPFC) has been a good target site for transcranial direct current stimulation (tDCS) due to its intense involvement in working memory. In our 2018 study, tDCS improved visual-verbal working memory in healthy subjects. Objective: This study examines the effects of tDCS on ADHD patients, particularly on verbal working memory. Methods: We conducted an experiment involving verbal working memory of two modalities, visual and auditory, and a sustained attention task that could affect working memory in 9 ADHD patients. Active or sham tDCS was applied to the left DLPFC in a single-blind crossover design. Results: tDCS significantly improved the accuracy of visual-verbal working memory. In contrast, tDCS did not affect auditory-verbal working memory and sustained attention. Conclusion: tDCS to the left DLPFC improved visual-verbal working memory in ADHD patients, with important implications for potential ADHD treatments.

The Impact of the Digital Economy on Rural Residents’Working Hours:Mechanisms and Empirical Evidence

The rapid development of the digital economy has provided a new impetus for rural residents to extend their working hours.Based on the data collected by the China Labor-force Dynamics Survey(CLDS)in 2014,2016,and 2018,this paper measured the development level of the digital economy in China from the perspectives of internet development and digital financial inclusion,and tested the mechanisms of how the digital economy affected rural residents’working hours.The results showed that the digital economy extended rural residents’working hours by expanding information channels and enhancing human capital,and this mechanism was affected by heterogeneity in rural residents’educational background,age,and social capital.Building on these findings,this paper holds that to increase rural residents’income by extending their working hours and achieving common prosperity for all,it is necessary to expand the opportunities for rural residents to participate in skills training and promote their accumulation of human capital.

Text Difficulty,Working Memory Capacity and Mind Wandering During Chinese EFL Learners’Reading

This experimental study investigated how text difficulty and different working memory capacity(WMC)affected Chinese EFL learners’reading comprehension and their tendency to engage in task-unrelated thoughts,that is,mind wandering(MW),in the course of reading.Sixty first-year university non-English majors participated in the study.A two-factor mixed experimental design of 2(text difficulty:difficult and simple)×2(WMC:high/large and low/small)was employed.Results revealed that 1)the main and interaction effects of WMC and text difficulty on voluntary MW were significant,whereas those on involuntary MW were not;2)while reading the easy texts,the involuntary MW of high-WMC individuals was less frequent than that of low-WMC ones,whereas while reading the difficult ones,the direct relationship between WMC and involuntary MW was not found;and that 3)high-WMC individuals had a lower overall rate of MW and better reading performance than low-WMC individuals did,but with increasing text difficulty,their rates of overall MW and voluntary MW were getting higher and higher,and the reading performance was getting lower and lower.These results lend support to WM theory and have pedagogical implications for the instruction of L2 reading.

借助外力 让感觉升华为思维——基于“Working Model”对2023年新课标卷第6题的拓展分析

“Working Model”是一个物理仿真模拟平台,可直观展示动力学中的物理过程和运动图像,形成真实的感觉。该平台可用于辅助教学,帮助学生通过感觉、知觉、记忆、想象、思维等认知过程来理解和掌握物理概念和规律。以2023年新课标卷第6题为切入点,结合近三年全国高考真题为例,探讨借助外力将感觉升华为思维的可能性,通过对“Working Model”的拓展分析提出一种新的思维模式,旨在帮助学生通过直观刺激和辅助工具将感觉体验转化为深度思考和创新思维。并通过理论分析和实证研究,探讨这种思维模式的实施方法、可行性和效果,为教育教学和认知科学领域的研究提供新的思路和启示。

Working Model在高中物理教学中的应用——以力学模型为例

基于Working Model的仿真实验功能,结合几个常见的力学运动模型展示Working Model在中学物理教学中的用途.利用Working Model将运动过程直观呈现,同时以数值、矢量、动态图像等输出形式将位移、速度和加速度等物理量同步反馈,以此进一步探究物理规律.

Few-shot working condition recognition of a sucker-rod pumping system based on a 4-dimensional time-frequency signature and meta-learning convolutional shrinkage neural network

The accurate and intelligent identification of the working conditions of a sucker-rod pumping system is necessary. As onshore oil extraction gradually enters its mid-to late-stage, the cost required to train a deep learning working condition recognition model for pumping wells by obtaining enough new working condition samples is expensive. For the few-shot problem and large calculation issues of new working conditions of oil wells, a working condition recognition method for pumping unit wells based on a 4-dimensional time-frequency signature (4D-TFS) and meta-learning convolutional shrinkage neural network (ML-CSNN) is proposed. First, the measured pumping unit well workup data are converted into 4D-TFS data, and the initial feature extraction task is performed while compressing the data. Subsequently, a convolutional shrinkage neural network (CSNN) with a specific structure that can ablate low-frequency features is designed to extract working conditions features. Finally, a meta-learning fine-tuning framework for learning the network parameters that are susceptible to task changes is merged into the CSNN to solve the few-shot issue. The results of the experiments demonstrate that the trained ML-CSNN has good recognition accuracy and generalization ability for few-shot working condition recognition. More specifically, in the case of lower computational complexity, only few-shot samples are needed to fine-tune the network parameters, and the model can be quickly adapted to new classes of well conditions.

Determinants of Breastfeeding Practices among Working Mothers in Solwezi District of Zambia

Background: As one of the strategies to reduce infant morbidity and mortality, the World Health Organization recommends early initiation of exclusive breastfeeding and timely introduction of complementary feeding with continued breastfeeding for up to two years or beyond. Although breastfeeding is a natural process, it is influenced by different socio-cultural factors, habits, standards, and behaviours. Rapid industrialization and changes in lifestyle have seen increasing numbers of women in the labour force, and associated poor Exclusive Breastfeeding practices among working mothers. The aim of this study was to identify the determinants of breastfeeding practices among working mothers in Solwezi District of Zambia. Methods: This was a cross-sectional comparative survey comparing determinants of breastfeeding practices among working mothers aged 15 - 49 years in urban and rural areas of Solwezi District. The study was carried out in the Under-five Clinics at Solwezi, Kimasala and Mushitala Urban Clinics, as well as St. Francis, Kapijimpanga and Kisalala Rural Health Centers. Eighty-seven participants were successfully recruited using convenience sampling. A researcher-assisted questionnaire was used to collect data. Data analysis was done using SPSS version 27.0. Descriptive statistical analysis was done using numerical measures such as measures of central tendency and dispersion. The Pearson Chi Square test, correlation and linear regression analysis were performed to test association between the variables at the 0.05 level of significance. Are you assessing exclusive breastfeeding alone or what? Results: The mean age of respondents was 27.44 years (SD = 6.042 years) and the majority of the respondents were married (71.3%, n = 62). Forty-three percent of the respondents were self-employed while the rest were in formal government or private sector employment. Overall, 97.7% of the respondents had heard of exclusive breastfeeding, with health facilities being the most frequent source of information (64.4%). Attitude towards exclusive breastfeeding was generally positive. Fifty-eight percent of respondents exclusively breastfed while the rest were on mixed feeding. Seventy-one percent of respondents reported that their workplaces did not have breastfeeding facilities at work. Only 11.5% of the respondents reported having cultural beliefs restricting breastfeeding. Statistically significant associations were obtained from cross-tabulation analysis between respondent’s occupation and baby feeding type (p 0.001);workload and feeding type (0.024);as well as knowledge of EBF and feeding type (p 0.001). Conclusion: Majority of the respondents demonstrated good knowledge and positive attitude towards exclusive breastfeeding. This study recommends sensitization campaigns in communities to raise awareness about the importance of breastfeeding, and foster behaviour change that promotes breastfeeding.

Online Peer Advice: Giving Advice on Chinese Social Networking Sites

This study investigates advice-giving in peer-to-peer comment sections on Chinese social networking sites. The results show that advice, explanation, experience, and assessment are the four most frequent discursive moves in Chinese advice given by peers on social networking sites. Involvement, mitigation, and face-threatening strategies are also utilized frequently by those peers to give directives and express empathy and solidarity on Chinese online sites, thereby building supportive relationships among them in online communities. The online peer advice-giving in this study is influenced by multiple aspects of the platform, participants, and language use, presenting distinctive characteristics that differ from other studies.

Research on the dynamic response of connecting rod bearing bush wear of reciprocating machine under variable working conditions

As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the bearing and the abnormal vibration of the body.Based on the characteristics of poor lubrication state and complex force of connecting rod small head bearing, a mixed lubrication model considering oil groove feed was established, and the dynamic simulation of the reciprocating compressor model with lubricated bearings was carried out;considering different speeds and gas load conditions, the law of the impact of the eigenvalues changing with working conditions was explored.The fault simulation experiment was carried out by selecting representative working conditions, which verified the correctness of the simulation method.The study found that two contact collisions between the pin and the bearing bush occurred in one cycle, the collision impact was more severe under the wear fault, and the existence of the gap made the dynamic response more sensitive to the change of working conditions.This research provides ideas for the location and feature extraction of fault symptom signal angular segments in the process of complex measured signal processing.

The laparoscopic rating scale for the evaluation of working conditions for surgical treatment of super-obesity

In this technical note,a novel rating scale(abdominal integral index)was introduced for assessing the conditions of the working laparoscopic space based on linear measurements to select the optimal one or two-stage surgical treatment for super-obesity.Patients with the same height and similar BMI values had different rating scale scores,reflecting different conditions of laparoscopic bariatric surgery.The rating scale helps surgeons and patients make a safe option for surgery,depending on the experience of the surgeon and technical laparoscopic conditions.

Study of energy-efficient heat resistance and cooling technology for high temperature working face with multiple heat sources in deep mine

In the present research,we proposed a scheme to address the issues of severe heat damage,high energy consumption,low cooling system efficiency,and wastage of cold capacity in mines.To elucidate the seasonal variations of environmental temperature through field measurements,we selected a high-temperature working face in a deep mine as our engineering background.To enhance the heat damage control cability of the working face and minimize unnecessary cooling capac-ity loss,we introduced the multi-dimensional heat hazard prevention and control method called"Heat source barrier and cooling equipment".First,we utilize shotcrete and liquid nitrogen injection to eliminate the heat source and implemented pressure equalization ventilation to disrupt the heat transfer path,thereby creating a heat barrier.Second,we establish divi-sional prediction models for airflow temperature based on the variation patterns obtained through numerical simulation.Third,we devise the location and dynamic control strategy for the cooling equipment based on the prediction models.The results of field application show that the heat resistance and cooling linkage method comply with the safety requirement throughout the entire mining cycle while effectively reducing energy consumption.The ambient temperature is maintained below 30℃,resulting in the energy saving of 10%during the high-temperature period and over 50%during the low-temperature period.These findings serve as a valuable reference for managing heat damage in high-temperature working faces.

On Answering the Question Related to the Legal Regulation of Working Hours in the New Era:Western Experience and Chinese Approach

The popularity of flexible working hours around the world has slowed down the historical trend of reducing working hours.It even shows signs of regression.Whether and how to guide the cur-rent society with flexible working hours to return to the historical track of reducing working hours,improve the quality of working hours,and promote a smooth transition from the era of traditional standard work-ing hours to the era of flexible working hours has become a question related to the legal regulation of working hours in the new era.In this regard,although Western countries have proposed new regulatory concepts and carried out legislative practices with distinctive charac-teristics,the limitations of legal regulation capabilities have prevented them from proposing a package of institutional solutions.The advan-tage of China in the ability of legal regulation of working hours has been gradually formed in the legislation on working hours unnder the leadership of the CPC in the past century.It enables China to break through the limitations of the West and propose a Chinese approach to answer the question of the legal regulation of working hours in the new era from three aspects:limiting the extension of working hours,improving the quality of flexible working hours,and optimizing the funnctions of the multi-funnctional regulatory system for working hours.

中日友好医院党建引领高质量发展实践与思考

公立医院党建工作是实现高质量发展的重要保障。本文以中日友好医院为例,介绍把党的政治建设、思想建设、组织建设、作风建设、纪律建设、制度建设与医院高质量发展紧密结合的实践探索,逐步形成以高质量党建引领高质量发展的“六提升”工作法,为公立医院党建引领高质量发展提供参考。

ChatGPT的法律人格认定与生成内容性质探讨

随着ChatGPT的广泛运用,关于人工智能的法律问题探讨再次成为舆论焦点。根据ChatGPT系统与人类互动生成相应文字内容的特性,ChatGPT生成内容是否受《著作权法》保护问题备受争议。探讨该问题,有两个不可或缺的前提要件,即ChatGPT是否具有法律人格及其生成内容能否被认定为作品,以此确定其是否应受《著作权法》保护。文本认为,ChatGPT尚不具备法律主体资格,在ChatGPT生成内容被认定为作品对其进行保护时,应明确ChatGPT使用者作为生成内容的著作权主体,通过加强对ChatGPT著作权主体的监管实现对其生成内容的规制,以此加快推进人工智能法治化进程。

基于供需理论的生成式人工智能赋能情报工作范式模型构建与应用研究

[目的/意义]当前生成式人工智能的发展对社会产生了强烈冲击。为响应国家创新发展的迫切需求,如何利用生成式人工智能更好地完成情报工作,以满足用户的情报需求,已成为当前情报学领域关注的热点问题。[方法/过程]基于供需理论提出从数据供给侧(Supply)、智慧情报分析中台(Analysis)、情报需求侧(Demand)三方构建生成式人工智能赋能情报工作范式模型——SAD范式模型,深入分析生成式人工智能赋能情报工作机理,并结合国际前沿项目案例探讨生成式人工智能与情报工作的前瞻性融合发展。[结果/结论]生成式人工智能赋能情报工作范式模型SAD,可以更好地促进生成式人工智能赋能情报工作的各个环节,提高情报工作效率,为情报工作范式研究提供了新思路。

数智技术赋能统战工作发展透视

数智技术与统战工作在价值理念和政治定位等层面具有高度契合性,前者可以满足后者信息化、智能化、精准化、动态化等发展需求,为后者高质量发展提供持续动能。数智技术能有效支撑和服务于统战工作、开拓统战工作数据应用新空间、激发统战工作新活力。当前我国数智统战工作取得了一些进展,但也面临数字化平台和工具应用不足、数据共享和协同体系不完善以及数智化人才短缺和统战干部理念更新不足等问题。因此,未来数智统战应综合运用数智技术,通过构建面向统战对象的大数据智能分析平台、开发数智化统战工作工具、丰富宣传内容和形式,推动统战工作凝聚人心、汇聚力量;通过制定统一的数智统战顶层设计和规划、构建统一开放的统战云平台、完善数智安全保障体系,赋能大统战工作格局的构建;通过推进协商数智化体系构建、建立政协系统数智人才培训与考核机制、加大新技术在协商业务流程中的应用,深化协商民主。