scholarly journals Experimental Analysis of Friction and Wear of Self-Lubricating Composites Used for Dry Lubrication of Ball Bearing for Space Applications

Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 38
Author(s):  
Guillaume Colas ◽  
Aurélien Saulot ◽  
Yann Michel ◽  
Tobin Filleter ◽  
Andreas Merstallinger
Keyword(s):  
Friction And Wear ◽  
Ball Bearing ◽  
Transfer Film ◽  
The Self ◽  
Space Applications ◽  
Long Period ◽  
Before And After ◽  
Space Mechanisms ◽  
Bearing Ball ◽  
Self Lubricating Composites

Lubricating space mechanisms are a challenge. Lubrication must be sustained in different environments, for a very long period of time, and without any maintenance possible. This study focuses on the self-lubricating composite used in the double transfer lubrication of ball bearing. Ball/races contacts are lubricated via the transfer of materials from the cage that is made of the composite. A dedicated tribometer has been designed for the study. A specificity of the tribometer is to not fully constrain the composite sample but to let it move, as the cage would do in the bearing. Four composites (PTFE, MoS2, glass or mineral fibers) where tested in ultrahigh vacuum and humid air environments. Transfer was achieved with morphologies and composition similar to what is observed on real bearings. Adhesion measurements performed on composite materials before and after friction allowed one to explain the differences in tribological behaviors observed (transfer quality and contact instabilities). Beyond strengthening the composites, fibers are shown to be critical in trapping mechanically and chemically the transferred material to lubricate and prevent instabilities. Equilibrium between internal cohesion of transferred material, and adhesion to counterparts must be satisfied. Mass spectrometry showed that water appears also critical in the establishment of stable transfer film, even in vacuum.

scholarly journals Wear and Friction Characteristics of 65Mn Steel for Spike-Tooth Harrow

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 319
Author(s):  
Zhiguo Lu ◽  
Chuanyu Du ◽  
Qingcai Chen ◽  
Tianying Niu ◽  
Na Wang ◽  
...  
Keyword(s):  
Friction And Wear ◽  
Working Environment ◽  
Manganese Steel ◽  
Wear Loss ◽  
Variable Parameters ◽  
Wear Characteristics ◽  
Before And After ◽  
Set Up ◽  
Worn Surface ◽  
Friction And Wear Characteristics

The friction and wear characteristics of spike-tooth material (65Mn steel) of Spike-Tooth Harrow in a two-stage peanut harvester were studied in this paper. The friction and wear tests of pin and disc on 65 manganese steel were carried out on the tribometer, then the wear loss and the friction coefficient were studied. The wear loss of the pin was acquired by calculating the mass of the pin before and after the experiment using an electronic balance. According to the actual working environment of peanut spring-finger, four variable parameters are set up: load, speed, soil moisture and soil type. The friction and wear characteristics of pins were studied under different loads, speeds and different soil environments. After wearing, the worn surface of the material was observed by scanning microscope and the wear mechanism was studied. The experimental results show that the wear of the pin increases with the increase of load and decreases with the increase of rotational speed in the same rotation number. Especially in the case of the sandy soil with 20% in moisture, a maximum wear loss of the pin is achieved.

scholarly journals Investigation of the Tribological Performances of Graphene and WS2 Nanosheets as Additives for Perfluoroalkylpolyethers Under Simulated Space Environment

2021 ◽  
Vol 69 (2) ◽  
Author(s):  
Jia Ren ◽  
Kuiliang Gong ◽  
Gaiqing Zhao ◽  
Wenjing Lou ◽  
Xinhu Wu ◽  
...  
Keyword(s):  
Amorphous Carbon ◽  
Atomic Oxygen ◽  
Friction And Wear ◽  
Surface Oxidation ◽  
Space Environment ◽  
Composition And Structure ◽  
Before And After ◽  
Wear Reduction ◽  
Ws2 Nanosheets ◽  
Effects Of Irradiation On

AbstractThe tribological performances of perfluoroalkylpolyethers (PFPE) with graphene (Gr), WS2, and the mixture of Gr and WS2 (Gr + WS2) before and after ultraviolet (UV), atomic oxygen (AO), and proton (Pr) irradiations were investigated. The composition and structure of PFPE, Gr, WS2, and Gr + WS2 were also analyzed to understand the effects of irradiation on the tribological behaviors of PFPE with additives. The results indicated that serious deterioration and degradation of PFPE took place and Gr was transformed to amorphous carbon after Pr irradiation, and surface oxidation of WS2 occurred under the irradiations of AO and Pr. Moreover, compared to PFPE and PFPE additized with Gr and WS2, PFPE with the addition of Gr + WS2 exhibited excellent friction and wear reduction before and after UV and AO irradiations. Graphical Abstract

scholarly journals Eficácia da simulação na autoconfiança de estudantes de enfermagem para ressuscitação cardiopulmonar extra-hospitalar: um estudo quase experimental

2019 ◽  
Vol 29 (1) ◽  
pp. 32694 ◽  
Author(s):  
Genesis Souza Barbosa ◽  
Caio Guilherme Silva Bias ◽  
Lorene Soares Agostinho ◽  
Luciana Maria Capurro de Queiroz Oberg ◽  
Rafael Oliveira Pitta Lopes ◽  
...  
Keyword(s):  
Nursing Students ◽  
Cardiopulmonary Resuscitation ◽  
Undergraduate Students ◽  
The Self ◽  
Significance Level ◽  
Self Confidence ◽  
Intervention Protocol ◽  
Before And After ◽  
Quasi Experimental ◽  
Confidence Scale

AIMS: To verify the effectiveness of the simulation in the self-confidence of nursing students for extra-hospital cardiopulmonary resuscitation. METHODS: A quasi-experimental, before and after, single-group study, was performed with nursing undergraduate students. The sample was recruited among university students who were in the second or third year of graduation and accepted to participate in the research. The intervention protocol consisted of individual participation in a emergency simulated clinical scenario. The simulated scenario adopted consisted of cardiopulmonary resuscitation in extra-hospital cardiorespiratory arrest, using the Mini Anne Plus® low fidelity manikin. In addition to the sociodemographic variables, students' self-confidence for emergency action was analyzed, evaluated by the Self-Confidence Scale, before and after each simulation. Marginal and homogeneous Wilcoxon homogeneity tests were applied, and the accepted significance level was 5%.RESULTS: Thirteen two undergraduate students in nursing between the ages of 18 and 38 participated in the study. Statistically significant differences (p < 0.001) were observed in the answers of all the questions of the Self-confidence Scale when compared before and after the simulation. There was also a statistically significant increase (p < 0.001) in cardiological, respiratory and neurological scores after simulation.CONCLUSIONS: The simulation proved to be an effective educational strategy in increasing the self-confidence of nursing students to perform extra-hospital cardiopulmonary resuscitation.

Influence of Human-oriented Nursing Mode on Self-Care Ability, Unhealthy Emotion and Quality of Life of Patients with Benign Prostatic Hyperplasia

2021 ◽  
Vol 7 (4) ◽  
pp. 635-646
Author(s):  
Feifei Peng ◽  
Guangchi Xu ◽  
Caihong Zhu ◽  
Lanchun Sun ◽  
Bo Dong ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Benign Prostatic Hyperplasia ◽  
Postoperative Complications ◽  
Self Care ◽  
Nursing Intervention ◽  
Prostatic Hyperplasia ◽  
The Self ◽  
Nursing Satisfaction ◽  
Before And After

To explore the influence of human-oriented nursing mode on the self-care ability, unhealthy emotion and quality of life of patients with benign prostatic hyperplasia (BPH), 147 patients with BPH admitted to our hospital from February 2018 to August 2019 were selected and all patients were separated into two groups on the basis of the nursing intervention mode. 77 cases in the research group (RG) were given the human-oriented nursing mode and 70 cases in the control group (CG) were given the conventional nursing mode. The bladder irrigation time (BIT), indwelling catheter time (ICT), postoperative hospitalization time (PHT) and the incidence rate of postoperative complications were observed in the two groups after nursing intervention. Before and after nursing intervention, the self-care ability of patients was evaluated in the two groups by Exercise of Self-Care Agency Scale (ESCA). In the two groups, the anxiety and depression status were evaluated by the Self-rating Anxiety Scale (SAS) and the Self-rating Depression Scale (SDS). The Quality of Life Scale for Benign Prostatic Hyperplasia Patient (BPHQLS) was applied to evaluate the quality of life in both groups before and after nursing intervention. The International Prostate Symptom Score (IPSS) was used to assess the lower urinary tract symptoms (LUTS) of patients in the two groups before and after nursing intervention. The self-made nursing satisfaction questionnaire was used to evaluate the nursing satisfaction in the two groups. The BIT, ICT and PHT in RG after nursing intervention were obviously lower than those in CG, and the incidence of postoperative complications in RG was also obviously lower than that in CG (p < 0.05). The ESCA score of patients in RG after nursing intervention was significantly higher than that in CG (P < 0.05). The SAS and SDS scores of patients in RG after nursing intervention were significantly lower than those in CG (P < 0.05). The BPHQLS score in RG after nursing intervention was obviously higher than that in CG (P < 0.05). The IPSS score of patients in RG after nursing intervention was obviously lower than that in CG (p < 0.05). The nursing satisfaction score in RG after nursing intervention was obviously higher than that in CG (p < 0.05).Condusion: The application effect of the human-oriented nursing mode on patients with BPH is definite, which can improve self-care ability, unhealthy emotion and effectively ameliorate the quality of life.

Psychological factors influencing motivation, cooperation, participation, satisfaction, self appraisal, and individual quality of life in adolescents and adults undergoing Orthodontic treatment

2021 ◽  
Vol 11 (1) ◽  
pp. 34-39
Author(s):  
Oshin Pawar ◽  
Purva Joneja ◽  
Deepak Singh Choudhary
Keyword(s):  
Quality Of Life ◽  
Psychological Factors ◽  
Orthodontic Treatment ◽  
The Self ◽  
Main Concern ◽  
Individual Quality ◽  
Patients Satisfaction ◽  
Before And After ◽  
Individual Quality Of Life

Introduction: To bring the best outcome from both the sides i.e. the orthodontist and the patient , it is of prime importance to understand certain psychological factors, and to treat every patient with an individualistic approach. The need was to study all such psychological factors and to find a method to deal with the same; to evaluate the psychological factors that influences the self appraisal and individual Quality of life. To compare psychological factor affecting the self appraisal and individual quality of life before treatment and after treatment, to study psychological factors of patients which influences the treatment outcome and to find a method to manage them. Materials and Method: This In-vivo study, includes case study and survey. Two separate sets of questionnaires (before and after undergoing orthodontic treatment) were given to patients. The study also included psychological test scales like OHIP-14 and 12-CSES. The sample size of patient was 150. Result: The study revealed that esthetics (95%) is the main concern for getting treatment especially for female (56%). There is improvement in OHIP and CSES (interval of 12.63, 14.66) score of patients before and after treatment. Patients’ satisfaction (94.7%) increases on having healthy orthodontist-patient relationship. Conclusion: Esthetics is the main concern. Most patients wants improvement in smile. Lack of awareness and lack of financial supports is the main reason for delay in getting treatment. The main discomfort about the treatment reported by participants was pain after activation appointments, ulcers and change in food eating habit. The orthodontic therapy improves confidence, satisfaction, individuals’ appraisal and quality of life. There were no variations in response for patients’ satisfaction by gender, age, education or by treatment duration.

Tribological properties of the epoxy resin-based solid lubricant coating modified by Kevlar fibers

2018 ◽  
Vol 70 (9) ◽  
pp. 1706-1713 ◽  
Author(s):  
Guotao Zhang ◽  
Yanguo Yin ◽  
Ting Xie ◽  
Dan Li ◽  
Ming Xu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Epoxy Resin ◽  
Tribological Properties ◽  
Dry Friction ◽  
Friction And Wear ◽  
Solid Lubricant ◽  
Transfer Film ◽  
Wear Properties ◽  
Content Type ◽  
Friction And Wear Properties

Purpose This paper aims to obtain high mechanical and good tribological properties of epoxy resin-based coatings under dry friction conditions. Design/methodology/approach Bonded solid lubricant coatings containing Kevlar fibres were prepared by a spraying method. The friction and wear properties of the coatings were experimentally investigated with a face-to-face tribometre under dry friction conditions. Scanning electron microscopy, energy dispersive X-ray spectroscopy and 3D laser scanning technologies were used to characterise the tribological properties. The action mechanism of the Kevlar fibres on a solid lubricant transfer film was also analysed. Findings Adding Kevlar fibres can significantly improve the wear resistance of the coatings. When the Kevlar fibre content increases, the tribological properties of the coatings improve and then worsen. Superior properties are obtained with 0.03 g of Kevlar fibres. Appropriately increasing the load or speed is beneficial to the removal of the outer epoxy resin and the formation of a lubricant film. During friction, the solid lubricants wrapped in the epoxy resin accumulate on the surface to form a transfer film that shows a good self-lubricating performance. In the later friction stage, fatigue cracks occur on the solid lubricant film but cannot connect to one another because of the high wear resistance and the entanglement of the rod-like Kevlar fibres. Thus, no large-area film falls from the matrix, thereby ensuring the long-term functioning of solid lubricant coatings. Originality/value Epoxy resin-based solid lubricant coatings modified by Kevlar fibres were prepared, and their friction and wear properties were investigated. Their tribological mechanisms were also proposed. This work provided a basis for the analysis of the tribological properties and design of bonded solid lubricant coatings containing Kevlar fibres.

scholarly journals Engagement of Occupational Safety and Health at Mahkamah’s Welding Worker Medan

2018 ◽  
Vol 1 (1) ◽  
pp. 48-53
Author(s):  
Eka Mahyuni ◽  
Kalsum ◽  
Muhammad Makmur Sinaga
Keyword(s):  
Occupational Safety ◽  
Occupational Safety And Health ◽  
The Self ◽  
Safety And Health ◽  
Before And After ◽  
Physical Risk ◽  
Result Show ◽  
Rest Time ◽  
Self Protection ◽  
Better Than

Welding worker was not the easy task because it has a very high physical risk and the process requires special skills and equipment to prevent accident exposed. This devotional activity is carried out in the welding industry at Jl. Mahkamah with two partners, namely CV. M. Nauli and CV. Cahaya. The aim of training activity made the worker able to analyze the hazards in the workplace so that it will be more careful in their work. The result show that the training could develop the worker to be aware about safety and health work patterns. In order to support the work in accordance with occupational safety and health standards, workers are also given pocket books that contain safety and health working methods and also given the self-protection of welding like welding clothes, welding gloves, welding mask, welding glasses and masks. Based on the evaluation of activities, it show that the worker has develop and always using the self protector in their work evenly. It build the good collaboration between them and they are could arrage the rest time with ergonomics relaxation in 5-10 minutes. The workshop station looks better than before and the workshop doing good house keeping before and after their work.

scholarly journals Revisiting AC bridges:A Novel Method to Measure Domestic Capacitors using Simple Techniques

10.29007/sgqk ◽  
2018 ◽  
Author(s):  
Ashish R. Patel ◽  
Dharita K. Patel ◽  
Jagadish K. Chauhan
Keyword(s):  
Mutual Inductance ◽  
The Self ◽  
Long Period ◽  
Analysis Tools ◽  
Novel Method

DC and AC bridges have been used in abundance for a long period of time for the component measurements as well as other parameters measurements. AC bridges are principally used for the determinations of component values and the associated parameters namely the self-inductance, mutual inductance, capacitance etc. In this paper the authors have presented a novel method using latest computing and analysis tools to investigate the capacitor ageing of a popular capacitor used in day to day life using a non-conventional AC bridge like circuit.

Self-assessment of Сompetencies as a Tool for Assessing the Effectiveness of Corporate Educational Programs

2021 ◽  
Vol 13 (4) ◽  
pp. 189-202
Author(s):  
M.M. Dmitrieva ◽  
S.V. Umnov ◽  
D.A. Podolsky
Keyword(s):  
Learning Outcomes ◽  
Training Programs ◽  
Corporate Training ◽  
Educational Programs ◽  
Assessment Method ◽  
The Self ◽  
Self Assessment ◽  
Assessment Of Learning ◽  
Before And After

The existing tools for assessing the effectiveness of educational programs differ in the degree of effectiveness, applicability, and costs. The self-assessment method, which involves the determination of the level of expression of various qualities by students of educational programs before and after graduation. The method of assessing students' own competencies has significant limitations associated with social desirability. Nevertheless, the article analyzes the possibilities of using this method to assess the effectiveness of corporate educational programs. The results of using the self-assessment method to assess the effectiveness of corporate educational programs conducted in large organizations are presented. The possibilities and limitations of using various kinds of criteria for evaluating themselves by listeners are substantiated. The conclusion is made about the possibility of using the self-assessment method in the case of the focus of educational programs on the development of meta-competencies of managers. The article provides data on the assessment of learning outcomes, discusses the potential reasons for the differences obtained in the framework of projects, as well as the possibilities and limitations of using the self-assessment method to assess the educational effect of corporate training programs.

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