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.

Determinants of Satisfaction at Work and Its Reflections on Performance

This study examines the relationship between job satisfaction and performance,investigating personality traits and satisfaction aspects among employees of a Federal Higher Education Institution.A questionnaire was administered to 658 participants,using structural equation modeling for analysis.Results highlighted that challenging work,neuroticism,and self-esteem significantly influenced overall workplace satisfaction,while general satisfaction,self-efficacy,and lack of attention were key determinants of work performance.This emphasizes the importance for managers to prioritize factors enhancing employee satisfaction,as it positively correlates with job performance.

Work-related quality of life and performance appraisal among nurses at a tertiary hospital in Philippines

Objective:The objective of the study is to describe the work-related quality of life(WRQOL)among nurses and explore its association with performance evaluation ratings.Methods:A cross-sectional design was utilized measuring the WRQOL scale and the previous performance appraisal rating.Multistage sampling approach was utilized with nurses stratified based on their position and then systematically random sampled based on their unit assignment.Results:One hundred and eighty-two nurses were included.About half reported a high quality of work life(101;55.5%).Low scores were noted on the subscale working conditions(100;54.9%),low to average responses for home-work interface(109;59.9%),control at work(100;54.9%),and stress at work(90;49.5%).A higher proportion of nurses reported positive responses toward the areas of general well-being(113;62.1%)and job-career satisfaction(112;61.5%),than in the other subscales.There were notable differences between WRQOL ratings:(1)Head nurses had the highest perceived quality of work life,followed by nurse supervisors and charge nurses(F=6.1,P<0.01)and(2)Nurses in the pay-patient services reported lower quality of working life,while those in office and outpatient services had more positive scores(F=4.6,P<0.01).Conclusion:Only more than half of the nurses reported a high quality of work life,some of its dimensions,particularly job and career satisfaction and working conditions,appeared to vary in the perceived degree across years in service,work hours,and position.The assessment of the quality of work life may serve as an important tool to address staff burnout,absenteeism and other issues that affect job performance among health-care professionals.

A Study on Organizational Commitment,Work Motivation,and Job Performance After the COVID-19 Epidemic in Taiwan-The Mediating Effects of Work Motivation and Organizational Communication

The purpose of this study is to explore the correlation between organizational commitment and job performance among employees in Taiwan Residents companies after the COVID-19 epidemic,and to use work motivation and organizational communication as intermediary variables to further understand the interaction between them.Using hierarchical multiple regression analysis and bootstrap method to analyze,the research results show that organizational commitment has a significant positive impact on work motivation and work performance,and work motivation also has a significant positive impact on work performance.In addition,organizational communication has a mediating effect on organizational commitment and work motivation,and work motivation also has a mediating effect on organizational commitment and work machine performance.The results of this study hope to understand the working conditions of organizations and employees after the COVID-19 epidemic,and provide relevant business operators with follow-up references for their operations.

IMPROVING ELEVATOR MAINTENANCE PERFORMANCE: WORK STUDY APPROACH

Strategic quality management is implemented in a local elevator company. Quality strategies, policies and goals focusing on customers′ needs are clearly established. Continuous quality improvement has been adopted as the corporate strategy to improve its performance and competitive edge. This paper presents the successful implementation of a quality improvement project using the work study approach. On the completion of the project, the rate of serious defects which may lead to an accident is reduced by 55%, i.e., from 2%￣0.9% over a period of two years. A total of HK$ 1.1 million spent on the project is justified when compared with the reduction of financial risks involved. The success of the project demonstrates that the work study approach could be an effective tool for improving the performance of maintenance work.

An integrative review of the influence of job strain and coping on nurses'work performance:Understanding the gaps in oncology nursing research

Nursing is known to be a stressful profession that can lead to physical and psychological health issues and behavioural problems.In oncology,workload among nurses is believed to be increasing in conjunction with rapidly increasing numbers of patients with cancer and staff shortages worldwide,therefore it is essential to sustain a quality oncology nurse workforce.Numerous studies have presented evidence on job strain,effects of coping strategies,and nurses'work performance within healthcare settings,but few have focused on oncology settings and none of these on nurses working in Saudi Arabia.The purpose of this review was to summarize empirical and theoretical evidence concerning job-related stressors in nurses,particularly oncology nurses,and the interrelationships among job strain,coping strategies,and work performance in this population.Search strategies identified studies published on studies in peer-reviewed journals from 2004 to 2016.Twenty-five nursing studies were found examining the relationships among the concepts of interest.Common job-related stressors among oncology nurses were high job demands,dealing with death/dying,lack of job control,and interpersonal conflicts at work.Job strain was found to be significantly linked to coping strategies,and negatively associated with work performance among nurses in general.There is no existing empirical evidence to support the relationship between coping strategies and work performance among oncology nurses.The present evidence is limited,and a considerable amount of research is required in the future to expand the oncology nursing literature.Research is needed to investigate job-related stressors and their effects on oncology nurses.

Effect of working parameters on performance characteristics of hydrostatic turntable by using FSI-thermal model

Effects of working parameters on performance characteristics of hydrostatic turntable are researched by applying the fluid-structure-thermal coupled model.Fluid-structure interaction(FSI)technique and computational fluid dynamics(CFD)method are both employed by this new model,and thermal effects are also considered.Hydrostatic turntable systems with a series of oil supply pressures,various oil recess depth and several surface roughness parameters are studied.Performance parameters,such as turntable displacement,system flow rate,temperature rise of lubrication,stiffness and damping coefficients,are derived from different working parameters(rotational speed of turntable and exerted external load)of the hydrostatic turntable.Numerical results obtained from this FSI-thermal model are presented and discussed,and theoretical predictions are in good agreement with the experimental data.Therefore,this developed model is a very useful tool for studying hydrostatic turntables.The calculation results show that in order to obtain better performance,a rational selection of the design parameters is essential.

Experimental study on the working performance of different milling tools for multistage fracturing ball seats

To achieve the secondary production in multistage fracturing wells of tight oil,milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later.In this paper,first of all,the working mechanism of milling tools for multistage fracturing ball seats was studied and a mechanical analysis model of single abrasive grain was established.Then,an experimental system for milling tools was developed,and the experimental tests of the flat,the blade,and the slope milling tool were conducted in order.Besides,the morphology of chips and the surface morphology of the workpiece after the experiment were analyzed.Also,the working performance of milling tools was evaluated from the perspectives of working safety,working efficiency,and wear resistance of the milling tool.The results show that the torque of the milling tool increases nonlinearly with the increase in the cutting depth of the abrasive grain and increases linearly with the increase in the cutting width.Also,the chips are irregular particles and the size is mainly from 10 to 50μm.So,the chips should be pumped up with a small pump pressure and a large displacement.Besides this,the cutting depths of the abrasive grains are from 216.20 to 635.47μm and the bottom surface of the milling tool should be eccentric to avoid the zero point of cutting speed.Furthermore,the torque of the slope milling tool is 23.8%larger than that of the flat milling tool,which is also 30.4%smaller than that of the blade milling tool.Compared with the flat milling tool,the working efficiency of the blade milling tool improves by 79.9%and the slope milling tool improves by 111.1%.Also,the wear resistance of the blade milling tool decreases by 102.7%,while the slope milling tool declines by 32.6%when compared with the flat milling tool.Therefore,the slope milling tool has the characteristics of moderate torque,stable working conditions,the highest working efficiency,and fine wear resistance,which is preferably used to mill multistage fracturing ball seats.This study provides a theoretical basis and guidance for milling multistage fracturing ball seats on-site and realizing production with a large diameter in later stages of multistage fracturing wells.

Latest progresses and the application of various electrolytes in high-performance solid-state lithium-sulfur batteries

With the emergence of some solid electrolytes(SSEs)with high ionic conductivity being comparable to liquid electrolytes,solid-state lithium-sulfur batteries(SSLSBs)have been widely regarded as one of the most promising candidates for the next generation of power generation energy storage batteries,and have been extensively researched.Though many fundamental and technological issues still need to be resolved to develop commercially viable technologies,SSLSBs using SSEs are expected to address the present limitations and achieve high energy and power density while improving safety,which is very attractive to large-scale energy storage systems.SSLSBs have been developed for many years.However,there are few systematic discussions related to the working mechanism of action of various electrolytes in SSLSBs and the defects and the corresponding solutions of various electrolytes.To fill this gap,it is very meaningful to review the recent progress of SSEs in SSLSBs.In this review,we comprehensively investigate and summarize the application of SSEs in LSBs to determine the differences which still exist between current progresses and real-world requirements,and comprehensively describe the mechanism of action of SSLSBs,including lithium-ion transport,interfacial contact,and catalytic conversion mechanisms.More importantly,the selection of solid electrolyte materials and the novel design of structures are reviewed and the properties of various SSEs are elucidated.Finally,the prospects and possible future research directions of SSLSBs including designing high electronic/ionic conductivity for cathodes,optimizing electrolytes and developing novel electrolytes with excellent properties,improving electrode/-electrolyte interface stability and enhancing interfacial dynamics between electrolyte and anode,using more advanced test equipment and characterization techniques to analyze conduction mechanism of Li^(+)in SSEs are presented.It is hoped that this review can arouse people’s attention and enlighten the development of functional materials and novel structures of SSEs in the next step.

Association of post-traumatic stress disorder and work performance: A survey from an emergency medical service, Karachi, Pakistan

BACKGROUND: The purpose of the study was to explore the association between posttraumatic stress disorder(PTSD) and work performance of emergency medical services personnel in Karachi, Pakistan.METHODS: Emergency medical service personnel were screened for potential PTSD using Impact of Event Scale-Revised(IES-R). Work performance was assessed on the basis of fi ve variables: number of late arrivals to work, number of days absent, number of days sick, adherence to protocol, and patient satisfaction over a period of 3 months. In order to model outcomes like the number of late arrivals to work, days absent and days late, negative binomial regression was applied, whereas logistic regression was applied for adherence to protocol and linear for patient satisfaction scores.RESULTS: Mean scores of PTSD were 24.0±12.2. No association was found between PTSD and work performance measures: number of late arrivals to work(RRadj 0.99; 0.98–1.00), days absent(RRadj 0.98; 0.96–0.99), days sick(RRadj 0.99; 0.98–1.00), adherence to protocol(ORadj 1.01; 0.99–1.04) and patient satisfaction(β 0.001%–0.03%) after adjusting for years of formal schooling, living status, coping mechanism, social support, working hours, years of experience and anxiety or depression.CONCLUSION: No statistically significant association was found between PTSD and work performance amongst EMS personnel in Karachi, Pakistan.

A Comparative Study of Performance Between Operators With Work Discontinuity and Without Work Discontinuity

In situations where discontinuity in operation occurs, specifically in a country where coontractualization has an increasing trend, the performance level of operators after the work break is of great interest. Existing studies have found that the performance of an operator declines after her operation is completely stopped. However, when the operator performed other tasks （may it be similar or not from her previous task） during the work break, the performance after the work break seems to be affected at different level. Contractual and regular operators from a semiconductor and textile company were considered to replicate a discontinuous and continuous operation. The processing times of contractual workers before and after several months of work break were compared. Two types of work break were seen to have significant effect on an operator＇s performance after the work break, Type 1： 0% to 40% similarity from previous task and Type 2： 40% to 97% similarity from previous task. One can find that when 21% of tasks performed during the work break are similar to the operator＇s previous task, there would be no change in her performance upon returning. On the other hand, a 5% decline in performance was observed after work break type 1 and an 8.54% improvement after work break type 2. Also, a remission rate of 18% from end of stint 1 to start of stint 2 under work break type 1 was seen, while 8% for work break type 2. This may also be true to other industries. Thus, further study is suggested.

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.

Early Maladaptive Schemas, Working Memory and Academic Performances of Moroccan Students

Our aim is to study the early maladaptive schemas and the memory span abilities and to evaluate the relationship between these schemas and the memory in one side and academic performance in the other side among Moroccan students. A cross-sectional study is conducted among 212 students, randomly selected from different institutions of the IBN TOFAIL University, located in the city of Kenitra (NW of Morocco). Three neurocognitive tests are used: the short version of the Early Maladaptive Schemas Questionnaire to evaluate the early maladaptive schemas (EMS), the sub-test of the Wechsler to evaluate the working memory among these subjects, and a general questionnaire about socio-economic data, nutritional and mental health status and also, academic performances of each student. The obtained results showed some significant negative correlations between forward memory span and activated schema, and significant negative correlations are registered between backward memory span and activated schema. More, thirty-three percent of students passed the exams of the autumn term against 67% who failed it. Moreover, significant negative correlations are registered between the schemas and the number of Units validated in the autumn term. In addition, fifty-three percent of students had a normal forward memory, 47% had an excellent forward memory and no one had pathological one. However, 63% had a pathological backward memory span, 28% had normal memory and 9% had an excellent backward memory. The EMS appeared in connection with the student’s working memory and the academic performance. Deeper investigations are needed to understand this relationship and also to study other possible factors that could affect this important neurocognitive function.

Mediating effect of work engagement between job characteristics and nursing performance among general hospital nurses

Objective:This study aimed to determine the effects of job characteristics and work engagement on the nursing performance of nurses working in general hospitals.Methods:Data were collected from 169 nurses who are working in a general hospital in South Korea by using a cross-sectional descriptive survey design.Results:Nurses’job characteristics and work engagement showed positive effects on nursing performance.This effect was magnified when work engagement was used as a mediating variable.Conclusions:The findings elucidate the factors influencing job performance and provide managers with important information for developing programs to improve the job skills and work engagement of nurses.

The Effects of the Work Environment on the Employees Optimal Performance: A Study of Ebonyi State College of Education, Ikwo

The study sought to investigate the effects of the work environment on the employees’optimal performance in Ebonyi State College of Education,Ikwo,as one of government organizations.The research design for this study was the survey research design to assess the relationship between the work environment and the employee’s performance in Ebonyi State College of Education.Thus,the population of the study comprised all employees of the college.The college which has total staff strength of 493 employees and seven management members making total of 500 was used as the study area.In an attempt to realize the objectives of the study,222 questionnaires were administered to both the management team and the employees of Ebonyi State College of Education.In order to ensure that all the strata of the population were fairly represented and all cases within each stratum had equal chance of being selected,stratified random sampling was used to select a sample of 215 employees and seven members of the management team for this research.A response rate of 78%was achieved.The data collected from both employees and managers was analyzed,using mean and standard deviation to answer the research questions and t-test statistics to test the hypotheses at alpha level of 0.05 significance.It was found that each of the components that define the work environment were statistically significant to performance of the college.However,the social work environment of employees of the college was the most conducive work environment in the institution and the psychological environment of the college was least conducive.In the end,the work environment of the Ebonyi State College of Education,Ikwo,was statistically significant to the performance of employees of the college.It was among other things recommended that for the performance of staff of the college to be enhanced,the college managers must improve its psychological environment so as to improve the psychological health of its employees.

The Effects of Work Ethics, Transformational and Transactional Leadership on Work Performance of Teachers

Teacher performance is an important factor to improve education performance. This study aimed to analyze the effect of the work ethics, transformational, and transactional leadership style on teacher performance. The experiment was conducted in public high school No. 112 Jakarta. A total of 50 teachers were included as samples, where they were given the questionnaires to be filled by self-rating. Data were analyzed with multiple linear regression model and processed with SPSS version 20. Results showed that transformational leadership, transactional leadership and work ethics have positive and significant impacts on teacher performance both simultaneously and individually.

Soil Uncertainties on Performance of Geotechnical Works

Performance-Based Design （PBD） is a more rational approach, particularly in seismic environments. In this approach it is relevant the performance required to structures and to geotechnical works, as well as the geotechnical constitutive models used to predict the performance. The parameters of the constitutive models are related in turn to soil properties. So soil properties are a key point for Performance-Based Design. Questions arising are： （i） which are the more relevant soil properties to solve a specific PBD geotechnical problem？ （ii） which are the more relevant model parameters and how they can be evaluated and/or correlated to soil properties？ （iii） which is the role of the soil parameters uncertainty in Performance-Based Design？ An answer to these questions is given in this paper, outlining the potential offered by the new advanced in-situ and laboratory tests and discussing the performance required by some geotechnical works.

A Study on the Correlation among FD-FI Cognitive Style,Working Memory Capacity and English Reading Performance among College EFL Learners

In the past few decades,there have been eminent interests in reading performance as essential means for language input.In view of that,extensive studies have been conducted to explore the factors that affect reading performance from various aspects.In the cognitive psychology field,some studies have examined the relationship between field dependent-field independent(FD-FI)cognitive styles and working memory capacity(WMC)on English reading,respectively.However,only limited studies focused on the correlation among FD-FI cognitive styles,WMC and English reading performance.Therefore,this study was conducted to explain these correlations.A total of 42 intermediate“English as Foreign Language”(EFL)learners participated in this study.In order to measure the learners’FD-FI cognitive style,WMC and English reading performance,the Cognitive Style Figures Test,reading span task and the International English Language Test System(IELTS)reading test were adopted,respectively.Data analyses such as Pearson’s correlation,independent sample t-test and two-way ANOVA were done using Statistical Package for the Social Science(SPSS)version 25.The results suggested a statistically significant correlation between FD-FI cognitive style and WM with English reading performance,respectively.The main effect of WM and FD-FI cognitive style is significant while the interaction between them is not significant in reading performance.

Performance analysis and comparison of PoW,PoS and DAG based blockchains

In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no technical analysis and comparison as a guideline to determine which type of consensus mechanism should be adopted in a specific scenario/application.To this end,this work investigates three mainstream consensus mechanisms in the blockchain,namely,Proof of Work(PoW),Proof of Stake(PoS),and Direct Acyclic Graph(DAG),and identifies their performances in terms of the average time to generate a new block,the confirmation delay,the Transaction Per Second(TPS)and the confirmation failure probability.The results show that the consensus process is affected by both network resource(computation power/coin age,buffer size)and network load conditions.In addition,it shows that PoW and PoS are more sensitive to the change of network resource while DAG is more sensitive to network load conditions.

Performance analysis of a 2-stroke micro free-piston swing engine

The micro free-piston swing engine （MFPSE） is a new structure, free-piston internal combustion engine. The dynamic model integrated MFPSE with a power generator and thermodynamic models in compression, power and scavenge processes based on the open thermodynamic systems were presented. A simulation was executed at given geometric parameters and initial conditions. The results manifest that the working principle of MFPSE is feasible.