Fundamentals of Tribology at the Atomic Level

1988 ◽  
Vol 140 ◽  
Author(s):  
John Ferrante ◽  
Stephen V. Pepper

AbstractTribology, the science and engineering of solid surfaces in moving contact, is a field that encompasses many disciplines: solid state physics, chemistry, materials science, and mechanical engineering. In spite of the practical importance and maturity of the field, the fundamental understanding of basic phenomena has only recently been attacked. In this paper we will attempt to define some of these problems and indicate some profitable directions for future research. We make three broad classifications: (1) fluid properties--compression, rheology, additives and particulates; (2) material properties of the solids--deformation, defect formation and energy loss mechanisms; and (3) interfacial properties--adhesion, friction chemical reactions, and boundary films. Research in the categories has traditionally been approached by considering macroscopic material properties. Recent activity has shown that some issues can be approached at the atomic level: that is, the atoms in the materials can be manipulated both experimentally and theoretically, and can produce results related to macroscopic phenomena. This experimental and theoretical activity is reviewed and related to the traditional research areas.

1991 ◽  
Vol 44 (3) ◽  
pp. 93-108 ◽  
Author(s):  
M. I. Flik

Thin films that are superconducting above liquid-nitrogen temperature possess promising applications in electronics and sensor technology. The design, the characterization and the processing of devices based on the high-temperature superconductors pose new fundamental heat transfer problems. This article reviews thermal conduction, thermal radiation and thermal stability phenomena in superconducting films. The understanding of these thermal phenomena requires solid-state physics and materials science, in addition to heat transfer and thermodynamics. Future research opportunities are pointed out for thermal problems in superconducting films.


2012 ◽  
Vol 485 ◽  
pp. 189-192
Author(s):  
Yan Hui Lv ◽  
Jin Shun Feng

Information science focuses on understanding problems from the perspective of the stakeholders involved and then applying information and other technologies as needed. New physics emerge because of the diverse new material properties which need to be explained. In this work, the notion of vector-valued multiresolution analysis and biorthogonal binary multi- tiwavelets is introduced. The existence of compactly supported biorthogonal vector-valued wavelets associated with a pair of biorthogonal compactly supported vector-valued scaling functions is investigated. A new method for constructing a class of biorthogonal compactly supported vector-valued wavelet functions is presented by using multiresolution analysis and matrix theory.


2020 ◽  
Author(s):  
Gabriel Freire Sanzovo Fernandes ◽  
Leonardo dos Anjos Cunha ◽  
Francisco Bolivar Correto Machado ◽  
Luiz Ferrão

<p>Chemical bond plays a central role in the description of the physicochemical properties of molecules and solids and it is essential to several fields in science and engineering, governing the material’s mechanical, electrical, catalytic and optoelectronic properties, among others. Due to this indisputable importance, a proper description of chemical bond is needed, commonly obtained through solving the Schrödinger equation of the system with either molecular orbital theory (molecules) or band theory (solids). However, connecting these seemingly different concepts is not a straightforward task for students and there is a gap in the available textbooks concerning this subject. This work presents a chemical content to be added in the physical chemistry undergraduate courses, in which the framework of molecular orbitals was used to qualitatively explain the standard state of the chemical elements and some properties of the resulting material, such as gas or crystalline solids. Here in Part 1, we were able to show the transition from Van der Waals clusters to metal in alkali and alkaline earth systems. In Part 2 and 3 of this three-part work, the present framework is applied to main group elements and transition metals. The original content discussed here can be adapted and incorporated in undergraduate and graduate physical chemistry and/or materials science textbooks and also serves as a conceptual guide to subsequent disciplines such as quantum chemistry, quantum mechanics and solid-state physics.</p>


2020 ◽  
Vol 13 ◽  
Author(s):  
Gaurav Gaurav ◽  
Abhay Sharma ◽  
G S Dangayach ◽  
M L Meena

Background: Minimum quantity lubrication (MQL) is one of the most promising machining techniques that can yield a reduction in consumption of cutting fluid more than 90 % while ensuring the surface quality and tool life. The significance of the MQL in machining makes it imperative to consolidate and analyse the current direction and status of research in MQL. Objective: This study aims to assess global research publication trends and hot topics in the field of MQL among machining process. The bibliometric and descriptive analysis are the tools that the investigation aims to use for the data analysis of related literature collected from Scopus databases. Methods: Various performance parameters are extracted, such as document types and languages of publication, annual scientific production, total documents, total citations, and citations per article. The top 20 of the most relevant and productive sources, authors, affiliations, countries, word cloud, and word dynamics are assessed. The graphical visualisation of the bibliometric data is presented in terms of bibliographic coupling, citation, and co-citation network. Results: The investigation reveals that the International Journal of Machine Tools and Manufacture (2611 citations, 31 hindex) is the most productive journal that publishes on MQL. The most productive institution is the University of Michigan (32 publications), the most cited country is Germany (1879 citations), and the most productive country in MQL is China (124 publications). The study shows that ‘Cryogenic Machining’, ‘Sustainable Machining’, ‘Sustainability’, ‘Nanofluid’ and ‘Titanium alloy’ are the most recent keywords and indications of the hot topics and future research directions in the MQL field. Conclusion: The analysis finds that MQL is progressing in publications and the emerging with issues that are strongly associated with the research. This study is expected to help the researchers to find the most current research areas through the author’s keywords and future research directions in MQL and thereby expand their research interests.


Author(s):  
Ronald E. Rice ◽  
Simeon J. Yates ◽  
Jordana Blejmar

We conclude the Handbook of Digital Technology and Society by identifying topics that appear in multiple chapters, are more unique to some chapters, and that represent general themes across the material. Each of these is considered separately for the ESRC theme chapters and the non-ESRC chapters. In the ESRC theme chapters, cross-cutting research topics include digital divides and inequalities; data and digital literacy; governance, regulation, and legislation; and the roles and impacts of major platforms. Cross-cutting challenges include methods; theory development, testing, and evaluation; ethics; big data; and multi-platform/holistic studies. Gaps include policy implications, and digital culture. In the non-ESRC chapters, more cross-cutting themes include future research and methods; technology venues; relationships; content and creation; culture and everyday life; theory; and societal effects. More unique, these were digitization of self; managing digital experience; names for the digital/social era; ethics; user groups; civic issues; health, and positive effects. The chapter also shows how the non-ESRC chapters may be clustered together based on their shared themes and subthemes, identifying two general themes of more micro and more macro topics. The identification of both more and less common topics and themes can provide the basis for understanding the landscape of prior research, what areas need to be included in ongoing research, and what research areas might benefit from more attention. The chapter ends with some recommendations for such ongoing and future research in the rich, important, and challenging area of digital technology and society.


2021 ◽  
Author(s):  
Polona Caserman ◽  
Augusto Garcia-Agundez ◽  
Alvar Gámez Zerban ◽  
Stefan Göbel

AbstractCybersickness (CS) is a term used to refer to symptoms, such as nausea, headache, and dizziness that users experience during or after virtual reality immersion. Initially discovered in flight simulators, commercial virtual reality (VR) head-mounted displays (HMD) of the current generation also seem to cause CS, albeit in a different manner and severity. The goal of this work is to summarize recent literature on CS with modern HMDs, to determine the specificities and profile of immersive VR-caused CS, and to provide an outlook for future research areas. A systematic review was performed on the databases IEEE Xplore, PubMed, ACM, and Scopus from 2013 to 2019 and 49 publications were selected. A summarized text states how different VR HMDs impact CS, how the nature of movement in VR HMDs contributes to CS, and how we can use biosensors to detect CS. The results of the meta-analysis show that although current-generation VR HMDs cause significantly less CS ($$p<0.001$$ p < 0.001 ), some symptoms remain as intense. Further results show that the nature of movement and, in particular, sensory mismatch as well as perceived motion have been the leading cause of CS. We suggest an outlook on future research, including the use of galvanic skin response to evaluate CS in combination with the golden standard (Simulator Sickness Questionnaire, SSQ) as well as an update on the subjective evaluation scores of the SSQ.


2021 ◽  
pp. 0272989X2199662
Author(s):  
Tammy C. Hoffmann ◽  
Mina Bakhit ◽  
Marie-Anne Durand ◽  
Lilisbeth Perestelo-Pérez ◽  
Catherine Saunders ◽  
...  

Background Patients and clinicians expect the information in patient decision aids to be based on the best available research evidence. The objectives of this International Patient Decision Aid Standards (IPDAS) review were to 1) check the currency of, and where needed, update evidence for the domain of “basing the information in decision aids on comprehensive, critically appraised, and up-to-date syntheses of the evidence”; 2) analyze the evidence characteristics of decision aids; and 3) propose updates to relevant IPDAS criteria. Methods We searched MEDLINE and PubMed to inform updates of this domain’s definitions, justifications, and components. We also searched 5 sources to identify all publicly available decision aids ( N = 471). Two assessors independently extracted each aid’s evidence characteristics. Results Minor updates to the definitions and theoretical justifications of this IPDAS domain are provided and changes to relevant IPDAS criteria proposed. Nearly all aids (97%) provided a year of creation/update, but most (81%) did not report an explicit update or expiration policy. No scientific references were cited in 33% of aids. Of the 314 that cited at least 1 reference, 39% cited at least 1 guideline, 44% cited at least 1 systematic review, and 23% cited at least 1 randomized trial. In 35%, it was unclear what statement in the aid the citations referred to. Only 14% reported any of the processes used to find and decide on evidence inclusion. Only 14% reported the evidence quality. Many emerging issues and future research areas were identified. Conclusions Although many emerging issues need to be addressed, this IPDAS domain is validated and criteria refined. High-quality patient decision aids should be based on comprehensive and up-to-date syntheses of critically appraised evidence.


2021 ◽  
Vol 13 (10) ◽  
pp. 5726
Author(s):  
Aleksandra Wewer ◽  
Pinar Bilge ◽  
Franz Dietrich

Electromobility is a new approach to the reduction of CO2 emissions and the deceleration of global warming. Its environmental impacts are often compared to traditional mobility solutions based on gasoline or diesel engines. The comparison pertains mostly to the single life cycle of a battery. The impact of multiple life cycles remains an important, and yet unanswered, question. The aim of this paper is to demonstrate advances of 2nd life applications for lithium ion batteries from electric vehicles based on their energy demand. Therefore, it highlights the limitations of a conventional life cycle analysis (LCA) and presents a supplementary method of analysis by providing the design and results of a meta study on the environmental impact of lithium ion batteries. The study focuses on energy demand, and investigates its total impact for different cases considering 2nd life applications such as (C1) material recycling, (C2) repurposing and (C3) reuse. Required reprocessing methods such as remanufacturing of batteries lie at the basis of these 2nd life applications. Batteries are used in their 2nd lives for stationary energy storage (C2, repurpose) and electric vehicles (C3, reuse). The study results confirm that both of these 2nd life applications require less energy than the recycling of batteries at the end of their first life and the production of new batteries. The paper concludes by identifying future research areas in order to generate precise forecasts for 2nd life applications and their industrial dissemination.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3605
Author(s):  
Haiyan Hu ◽  
Aiping Liu ◽  
Yuehua Wan ◽  
Yuan Jing

Energy storage ceramics is among the most discussed topics in the field of energy research. A bibliometric analysis was carried out to evaluate energy storage ceramic publications between 2000 and 2020, based on the Web of Science (WOS) databases. This paper presents a detailed overview of energy storage ceramics research from aspects of document types, paper citations, h-indices, publish time, publications, institutions, countries/regions, research areas, highly cited papers, and keywords. A total of 3177 publications were identified after retrieval in WOS. The results show that China takes the leading position in this research field, followed by the USA and India. Xi An Jiao Tong Univ has the most publications, with the highest h-index. J.W. Zhai is the most productive author in energy storage ceramics research. Ceramics International, Journal of Materials Science-Materials in Electronics, and the Journal of Alloys and Compounds are the most productive journals in this field, and materials science—multidisciplinary is the most frequently used subject category. Keywords, highly cited papers, and the analysis of popular papers indicate that, in recent years, lead-free ceramics are prevalent, and researchers focus on fields such as the microstructure, thin films, and phase transition of ceramics.


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