scholarly journals Tribological Properties of Oxide Coatings Produced on EN AW-5251 Alloy using Different Distances between Electrodes

2019 ◽  
Vol 1 (1) ◽  
pp. 400-405
Author(s):  
Marek Bara ◽  
Renata Dwornicka
Keyword(s):  
Tribological Properties ◽  
Geometrical Structure ◽  
Reciprocating Motion ◽  
Oxide Coatings ◽  
Tribological Test ◽  
Electric Charge Density ◽  
Hard Anodizing ◽  
Before And After ◽  
The Subject ◽  
Tribological Parameters

Abstract The subject of the presented work was the analysis of the influence of the distance between the electrodes using in the coating process on the tribological properties of oxide coatings. Oxide coatings were prepared on EN AW-5251 aluminum alloy samples. The samples surfaces were subjected to hard anodizing process in a multicomponent electrolyte based on sulfuric acid with an addition of organic acids. Anodizing was carried out with a constant electric charge density of 180 A·min/dm2. The distances between the electrodes for subsequent samples increased every 0.125 m up to 1 m. The tribological partner in a sliding couple with oxide layers was pin of PEEK/BG. Tribological tests were conducted on a T-17 tester in reciprocating motion, in technically dry friction conditions. Before and after tribological test, examination of the geometrical structure of counter-specimens’ surface was carried out using the Form Talysurf contact profilographometer, via a 3D method. The most satisfactory tribological parameters were obtained for the PEEK/BG association with the coating produced at a distance between the electrodes equal to 0.25 m.

scholarly journals Tribological Properties of the Oxide Coatings Produced onto 6061-T6 Aluminum Alloy in the Hard Anodizing Process

2018 ◽  
Vol 27 (7) ◽  
pp. 3268-3275 ◽  
Author(s):  
Przemysław Kwolek ◽  
Krzysztof Krupa ◽  
Andrzej Obłój ◽  
Paweł Kocurek ◽  
Małgorzata Wierzbińska ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Tribological Properties ◽  
Oxide Coatings ◽  
Hard Anodizing

THE INFLUENCE OF ION IMPLANTATION ON THE PROPERTIES OF Ti6Al4V TITANIUM ALLOY IN BIOTRIBOLOGICAL SYSTEMS

Tribologia ◽  
2020 ◽  
Vol 292 (4) ◽  
pp. 27-36
Author(s):  
Dariusz Ozimina ◽  
Katarzyna Piotrowska ◽  
Monika Madej ◽  
Arkadiusz Granek
Keyword(s):  
Titanium Alloy ◽  
Ion Implantation ◽  
Tribological Properties ◽  
Wear Mechanism ◽  
Geometrical Structure ◽  
Tribological Tests ◽  
Mechanical And Tribological Properties ◽  
Before And After ◽  
Instrumental Indentation ◽  
Titanium Alloy Ti6al4v

The article is devoted to the assessment of the geometrical structure of the surface as well as the mechanical and tribological properties of the surface layers obtained in the process of ion implantation. The titanium alloy Ti6Al4V used in biotribological systems was implanted with nitrogen and argon ions. Investigations of the geometrical structure of the surface before and after the tribological tests were carried out using confocal microscopy. The hardness of the tested materials was determined by the instrumental indentation method using a Vickers indenter. A nanotribometer was used for tribological tests. The tests were carried out in a reciprocating motion under conditions of technically dry friction and friction with the lubrication of Ringer's solution. SEM scanning microscopy was used to determine the width of the wear pattern and the wear mechanism. The conducted research showed that the hardness of the tested materials increased as a result of ion implantation. The tribological tests showed that the use of ion implantation improves the tribological properties, and the dominant wear mechanism was abrasive wear.

Efferent vagal innervation of canine ventricle

1985 ◽  
Vol 248 (1) ◽  
pp. H89-H97 ◽  
Author(s):  
N. Takahashi ◽  
M. J. Barber ◽  
D. P. Zipes
Keyword(s):  
Coronary Artery ◽  
Vagal Stimulation ◽  
Left Ventricular ◽  
Constant Infusion ◽  
Epicardial Surface ◽  
Before And After ◽  
Vagal Innervation ◽  
The Subject ◽  
Infusion Of Norepinephrine ◽  
The Right

The route efferent vagal fibers travel to reach the left ventricle is not clear and was the subject of this investigation. We measured left ventricular and septal effective refractory period (ERP) changes during vagal stimulation and a constant infusion of norepinephrine, before and after phenol was applied at selected sites of the heart to interrupt efferent vagal fibers that may be traveling in that area. Phenol applied to the atrioventricular (AV) groove between the origin of the right coronary artery anteriorly to the posterior descending branch of the circumflex coronary artery completely eliminated vagal-induced prolongation of ERP in the anterior and posterior left ventricular free wall and reduced, but did not eliminate, ERP prolongation in the septum. A large (3-cm radius) epicardial circle of phenol prevented vagal-induced ERP prolongation within the circle in all dogs, while a small (1-cm radius) epicardial circle of phenol failed to prevent vagal-induced ERP changes within the circle in any dog. An intermediate (2-cm radius) circle eliminated vagal effects on ERP in 13 of 18 dogs. Arcs of phenol, to duplicate the upper portion of the circle, applied sequentially from apex to base eliminated efferent vagal effects only when painted near or at the AV groove. We conclude that the majority of efferent vagal fibers enroute to innervate the anterior and posterior left ventricular epicardium cross the AV groove within 0.25-0.5 mm (depth of phenol destruction) of the epicardial surface.(ABSTRACT TRUNCATED AT 250 WORDS)

The Israeli–Lebanese war of 2006: consequences for Lebanon

2008 ◽  
Vol 1 (2) ◽  
pp. 187-210
Author(s):  
Ziad Hafez
Keyword(s):  
Arab Countries ◽  
The Political ◽  
National Unity ◽  
Major Consequence ◽  
Political Narrative ◽  
Defence Policy ◽  
Before And After ◽  
The Usa ◽  
The Subject ◽  
The Impact

This article focuses on the political narrative in Lebanon before and after the Israeli war against Lebanon in 2006. It revolves around the subject of national unity as a sine qua non condition for success for the Lebanese resistance led by Hezbollah. A major consequence of the narrative on national unity is the need to build a modern state and establish a cohesive defence policy. The paper also examines the impact of the war on Lebanon's economy and on its relations with the rest of the world (the USA, France, Syria, Arab countries, and Iran).

Improving Student Creativity Activeness And Implementation Approach In Cbsa On Civics Lesson Grade Ii Sd Negeri 39 Lengayang Gompong.Kec Markets Academic Year 2016/2017

2018 ◽  
Vol 1 (2) ◽  
pp. 89-96
Author(s):  
Darleli Darleli
Keyword(s):  
Civic Education ◽  
Evaluation Study ◽  
Class Action ◽  
Peer Tutors ◽  
Implementation Approach ◽  
Before And After ◽  
Study Population ◽  
Grade Ii ◽  
The Subject ◽  
Academic Year

    The purpose of this study is to prove that the use of the environment around the school can improve students' understanding of the subject Civic Education in Elementary School student 39 Class II Gompong Market. This study uses a class action approach. The study population was taken of all students in grade II , the data collection techniques used artificial teacher learning achievement test. Actions performed a total of two cycles. Data analysis techniques used analysis of the percentage of change in the results of the evaluation study before and after tutoring services with peer tutors. Thus there is an increase in students' mastery of the first cycle and the second cycle. Based on the above, it can be made a conclusion as follows: " Improving Student Creativity activeness And Implementation Approach In CBSA On Civics Lesson Grade II SD Negeri 39 Lengayang Gompong.Kec Markets Academic Year 2016/2017 " .    

scholarly journals Effect of Temperature on the Tribological Properties of Selected Thermoplastic Materials Cooperating with Aluminium Alloy

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7318
Author(s):  
Anita Ptak ◽  
Paula Taciak ◽  
Wojciech Wieleba
Keyword(s):  
Aluminium Alloy ◽  
Contact Pressure ◽  
Tribological Properties ◽  
Polymer Materials ◽  
Effect Of Temperature ◽  
Test Results ◽  
Friction Process ◽  
Before And After ◽  
Pin On Disc ◽  
Two Parameters

This article concerns the tribological properties of three selected polymer materials: polyamide PA6, polyethylene PE-HD and polyetheretherketone composite PEEK/BG during sliding against aluminium alloy EN AW-2017A in the presence of hydraulic oil HLP 68. The tests were carried out under contact pressure p of 3.5–11 MPa at ambient temperature T ranging from −20 °C to +20 °C. The dependence of kinetic friction coefficient μk on the two parameters was determined through tribological tests carried out using a pin-on-disc tribometer. A five-level central composite rotatable design (CCRD) was adopted for the experiment. All the test results were statistically analysed. The microhardness of the surface of the polymeric material was measured before and after the friction process. The surface was also examined under SEM. Temperature and contact pressure have been found to have a significant effect on the tribological properties of the tested sliding pairs. Relative to the applied friction conditions, the surfaces after friction showed rather heavy signs of wear.

scholarly journals Avaliação Social Construtivista de uma Experiência em EAD: o uso do COLLES enquanto instrumento de coleta de dados

EAD em FOCO ◽  
2016 ◽  
Vol 6 (2) ◽  
Author(s):  
Fernanda Roda Cassundé ◽  
Edson Gomes Silva ◽  
Laís da Silva Santos ◽  
Adler Henrique Santos Souza ◽  
Graça Suely Gomes Souza ◽  
...  
Keyword(s):  
Distance Education ◽  
Learning Environment ◽  
Public Management ◽  
Self Assessment ◽  
Before And After ◽  
Postgraduate Studies ◽  
On Line ◽  
The Subject ◽  
On Line Learning ◽  
Assessment Questionnaire

O presente trabalho tem como objetivo avaliar as expectativas e experiências dos estudantes em relação à disciplina O Estado e os problemas contemporâneos, do Curso de Especialização em Gestão Pública da Universidade Federal do Vale do São Francisco (Univasf). Para isso, foi realizada a aplicação do questionário de autoavaliação Colles (Constructivist Online Learning Environment Survey) verificando-se as possíveis mudanças na percepção e comparando-se os resultados do antes e do depois referente a seis dimensões: relevância, reflexão, interação, apoio dos tutores, apoio dos colegas e compreensão. Participaram da pesquisa 97 alunos, em dois momentos diferentes: no início das aulas, para conhecer as expectativas dos estudantes e no final delas, para se ter uma compreensão da realidade vivenciada. Os resultados revelaram que a análise da experiência sempre foi inferior quando comparada à análise da expectativa em todos os aspectos apresentados, evidenciando que alguns participantes sentenciaram não ter alcançado os objetivos pretendidos.Palavras-chave: Colles, Educação a distância, Avaliação, Pós-graduação, PNAP.  Social Constructivist Evaluation of an Experience in Distance Education: the use of Colles as Data Collection InstrumentAbstract This study aims to evaluate the students expectations and experiences regarding the subject "The State and the contemporary problems", in Public Management post-graduation from the Federal University of São Francisco Valley (UNIVASF). For this, the application carried out the self-assessment questionnaire COLLES (Constructivist On-line Learning Environment Survey) checking for possible changes in perception and comparing the results before and after referring to the six dimensions: relevance, reflection, interaction, support tutors, peer support and understanding. The participants were 97 students in two different times at the beginning of classes, to meet the expectations of students and at the end of these, to have an understanding of experienced reality. The results showed that the students' experience overcame the negative assessment in all aspects presented, showing that some participants sentenced not have achieved the intended objectives.Keywords: COLLES, Distance education, Evaluation, Postgraduate studies, PNAP. 

scholarly journals Jesse Shera, The Wars and The Pietá

2017 ◽  
Vol 11 (2) ◽  
Author(s):  
Rodrigo Porto Bozzetti ◽  
Gustavo Saldanha
Keyword(s):  
World War Ii ◽  
Social Epistemology ◽  
Information Science ◽  
World War ◽  
Social Approach ◽  
Theoretical Formulation ◽  
Social Nature ◽  
The Future ◽  
Before And After ◽  
The Subject

The purpose of this paper, considering the relevance of Shera thoughts and its repercussions, is to reposition, in epistemological-historical terms, Jesse Shera’s approaches and their impacts according to a relation between life and work of the epistemologist. Without the intention of an exhaustive discussion, the purpose is to understand some unequivocal relations between the Shera critique for the context of its theoretical formulation and the consequences of this approach contrary to some tendencies originating from the technical and bureaucratic roots of the field (before and after World War II). It is deduced that Shera, rather than observing the sociopolitical reality and technical partner in which the texture of alibrary-based thought (but visualized by him as documentaryinformational), establishes, in his own praxis, social epistemology as a sort of "critique of the future," that is, as a praxis of the reflexive activity of the subject inserted in this episteme. In our discussion, the epistemological-social approach represents a vanguard for the context of its affirmation, a reassessment for the immediate decades to its presentation(years 1960 and 1970) and a critique for the future of what was consolidated under the notion of information Science, anticipating affirmations of "social nature" of the 1980s and 1990s in the field of information.

scholarly journals Pengembangan bahan ajar berbasis muatan lokal pada mata kuliah Pendidikan Kewarganegaraan

2016 ◽  
Vol 13 (2) ◽  
pp. 113-126
Author(s):  
Emil El Faisal ◽  
Sulkipani Sulkipani
Keyword(s):  
Student Achievement ◽  
Civic Education ◽  
Field Evaluation ◽  
Pilot Project ◽  
Local Content ◽  
Before And After ◽  
The Subject ◽  
The Mean ◽  
Potential Impact ◽  
History Department

This research aimed at (1) developing teaching materials based on local content for Civic Education in University; and (2) describing the potential impact of local content on student consciousness on local culture. It was a developmental research. The subject were student registered in Civic Education Course (Mata Kuliah PKn) at History Department. Pilot project was validated through one to one, small group, and field evaluation. The analyzed result indicates that the developed instrument was valid and has potential impact. Supported data shows that the mean score prior to implementation was 6.86 and after implementation was 7.73. In other words, there was an increasing student achievement before and after its implementation. Accordingly, we suggest that this developed material could be implemented widely.

scholarly journals The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on Their Tribological Properties at Elevated Temperatures

2020 ◽  
Author(s):  
Alexey Vereschaka ◽  
Sergey Grigoriev ◽  
Vladimir Tabakov ◽  
Mars Migranov ◽  
Nikolay Sitnikov ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Elevated Temperatures ◽  
Composite Coatings ◽  
Multilayer Composite ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Tribological Parameters ◽  
Adhesion Component

The chapter discusses the tribological properties of samples with multilayer composite nanostructured Ti-TiN-(Ti,Cr,Al,Si)N, Zr-ZrN-(Nb,Zr,Cr,Al)N, and Zr-ZrN-(Zr,Al,Si)N coatings, as well as Ti-TiN-(Ti,Al,Cr)N, with different values of the nanolayer period λ. The relationship between tribological parameters, a temperature varying within a range of 20–1000°C, and λ was investigated. The studies have found that the adhesion component of the coefficient of friction (COF) varies nonlinearly with a pronounced extremum depending on temperature. The value of λ has a noticeable influence on the tribological properties of the coatings, and the nature of the mentioned influence depends on temperature. The tests found that for the coatings with all studied values of λ, an increase in temperature first caused an increase and then a decrease in COF.

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