The behaviour of lubricants in elastohydrodynamic contacts

Author(s):  
A. J. Moore

Difficulties once found in accounting for the tractional behaviour of lubricants in elastohydrodynamic (EHD) contacts have largely been resolved. A wealth of research stimulated by this problem has gradually unravelled the underlying rheological complexities and laid the basis for a coherent physical explanation. The understanding achieved and the problems that remain are briefly reviewed. Despite the advances made in rheological modelling, developments are not readily taken up by those engaged in theoretical investigations. Although computational complexity must inevitably rise when lubricants are modelled realistically, the penalty for not doing so must be clearly understood. The implications can be readily devined from previous research findings. Progress made in the exploration of EHD film thickness is also examined. Similarities and differences in film-forming behaviour in thick film (> 0.1 μm) and thin film (< 0.1 μm) regimes are identified and consideration given to the interpretational difficulties that may arise as EHD and boundary regimes begin to merge. Finally, a few observations are made on the value of EHD lubrication studies to automotive engineering.

Author(s):  
C. Meunier ◽  
D. Mazuyer ◽  
P. Vergne ◽  
M. El Fassi ◽  
J. Obiols

The rheological behavior of fresh and aged diesel LowSaps 5W30 lubricant, is studied with both ElastoHydroDynamic tribometer, and low shear and high shear viscometers. The evolution of the film thickness in EHD contact, that varies between 1nm and 150 nm, displays two types of lubrication process according to rolling speed. On the one hand, a classical EHD behaviour, controlled by viscosity, may be observed beyond 35 nm with a significant shear thinning effect in the range of temperatures. On the other hand, below 35nm, a steep drop of film thickness indicates the unability of the viscosity improver polymer to form a thin film within the contact. These observations are closely related to rheological measurements carried out in a shear rate range from 10s−1 to 107s−1, and temperatures between 25°C and 150°C. Indeed, analysis of two rheological parameters, polymer relaxation time and hydrodynamic radius, may explain non newtonian and thin film effects in the EHD experiments. A rheological modelling based on the Cross model is developed to calculate these parameters. Then, the principle of time-temperature equivalence is used to map the characteristics of lubricants. Finally, the approach coupling EHD tribometer\Viscometer is applied to lubricants which have been degraded during a light duty diesel engine test.


Author(s):  
D. M. Davies ◽  
R. Kemner ◽  
E. F. Fullam

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.


2013 ◽  
Vol 61 (3) ◽  
pp. 731-735
Author(s):  
A.W. Stadler ◽  
Z. Zawiślak ◽  
W. Stęplewski ◽  
A. Dziedzic

Abstract. Noise studies of planar thin-film Ni-P resistors made in/on Printed Circuit Boards, both covered with two different types of cladding or uncladded have been described. The resistors have been made of the resistive-conductive-material (Ohmega-Ply©) of 100 Ώ/sq. Noise of the selected pairs of samples has been measured in the DC resistance bridge with a transformer as the first stage in a signal path. 1/f noise caused by resistance fluctuations has been found to be the main noise component. Parameters describing noise properties of the resistors have been calculated and then compared with the parameters of other previously studied thin- and thick-film resistive materials.


Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 204
Author(s):  
Yuhao Zhou ◽  
Bowen Ji ◽  
Minghao Wang ◽  
Kai Zhang ◽  
Shuaiqi Huangfu ◽  
...  

Remarkable progress has been made in the high resolution, biocompatibility, durability and stretchability for the implantable brain-computer interface (BCI) in the last decades. Due to the inevitable damage of brain tissue caused by traditional rigid devices, the thin film devices are developing rapidly and attracting considerable attention, with continuous progress in flexible materials and non-silicon micro/nano fabrication methods. Therefore, it is necessary to systematically summarize the recent development of implantable thin film devices for acquiring brain information. This brief review subdivides the flexible thin film devices into the following four categories: planar, open-mesh, probe, and micro-wire layouts. In addition, an overview of the fabrication approaches is also presented. Traditional lithography and state-of-the-art processing methods are discussed for the key issue of high-resolution. Special substrates and interconnects are also highlighted with varied materials and fabrication routines. In conclusion, a discussion of the remaining obstacles and directions for future research is provided.


MRS Bulletin ◽  
2004 ◽  
Vol 29 (6) ◽  
pp. 376-384 ◽  
Author(s):  
Cherie R. Kagan ◽  
Mark A. Ratner

AbstractThis issue of MRS Bulletin on molecular transport junctions highlights the current experimental and theoretical understanding of molecular charge transport and its extension to the rapidly growing areas of molecular and carbon nanotube electronics. This introduction will outline the progress that has been made in understanding the mechanisms of molecular junction transport and the challenges and future directions in exploring charge transport on the molecular scale. In spite of the substantial challenges, molecular charge transport is of great interest for its intrinsic importance to potential single-molecule electronic, thin-film electronic, and optoelectronic applications.


2019 ◽  
Vol 4 (1) ◽  
pp. 1-19
Author(s):  
Zarisnov Arafat ◽  
Muhammad Gary Gagarin Akbar

Ekstradisi secara universal hingga saat ini mengalami perubahan yang semakin baik, terutama setelah kehidupan bernegara sudah mulai tampak lebih maju sampai abad 20 ini. Hubungan dan pergaulan internasional menemukan bentuk dan substansinya yang baru dan berbeda dengan zaman sebelum Perjanjian Perdamaian Westphalia tahun 1648. Negara-negara yang berdasarkan atas prinsip kemerdekaan kedaulatan dan kedudukan sederajat mulai menata dirinya masing-masing terutama masalah domestik dengan membentuk dan mengembangkan hukum nasionalnya, yang salah satunya di bidang hukum pidana nasional. Hukum pidana nasional masing-masing negara, terutama jenis-jenis kejahatan atau tindak pidananya, disamping pula ada kesamaan dan perbedaannya. Semakin menguat batas wilayah dan kedaulatan teritorial masing-masing negara, semakin menguat pula penerapan hukum nasionalnya di dalam batas wilayah negara masing-masing. Semakin banyaknya perjanjian-perjanjian yang dibuat oleh negara-negara baik bilateral ataupun multilateral untuk mengatur suatu masalah tertentu yang sudah, sedang, dan akan dihadapi. Dalam pembuatan perjanjian tersebut mulai dilakukan pengkhususan atas substansinya, jadi tidak lagi satu perjanjian mencakup berbagai macam substansi yang berbeda-beda. Di Indonesia peraturan mengenai Ekstradisi dibuat pada tahun 1979, mengingat hingga saat ini belum terjadi perubahan di dalam Undang-Undang Nomor 1 Tahun 1979 padahal PBB telah membuat suatu model pembuatan perjanjian ekstradisi pada tahun 1990, sehingga sudah selayaknya peraturan mengenai ekstradisi di Indonesia harus mengalami pembaharuan ke depan yang lebih baik. Kata Kunci: Ekstradisi, Politik Hukum, Hukum Pidana.   Abstract Extradition is universally up to now experiencing increasingly good changes, especially after the state of life has begun to appear more advanced until the 20th century. International relations and relationships find new and different forms and substance from the times before the Treaty of Peace of Westphalia in 1648. Countries that are based on the principle of freedom of sovereignty and equal position begin to organize themselves, especially domestic problems by forming and developing national laws, which one of them is in the field of national criminal law. The national criminal law of each country, especially the types of crime or criminal acts, besides there are similarities and differences. The stronger regional boundaries and territorial sovereignty of each country, the stronger the application of national laws within the borders of each country. The increasing number of agreements made by countries both bilaterally and multilaterally to regulate a particular problem that has been, is being, and will be faced. In making these agreements, specialization of the substance began to be carried out, so no more than one agreement covers a variety of different substances. In Indonesia, the Extradition regulation was made in 1979, considering that until now there had been no changes in Law Number 1 of 1979 even though the United Nations had made a model for making an extradition treaty in 1990, so that proper regulations on extradition in Indonesia must undergo reform better future.                                   Keyword: Extradition, Politics of Law, The Criminal Law.                                                                        


2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Angga Hermawan ◽  
Ni Luh Wulan Septiani ◽  
Ardiansyah Taufik ◽  
Brian Yuliarto ◽  
Suyatman ◽  
...  

AbstractMolybdenum-based materials have been intensively investigated for high-performance gas sensor applications. Particularly, molybdenum oxides and dichalcogenides nanostructures have been widely examined due to their tunable structural and physicochemical properties that meet sensor requirements. These materials have good durability, are naturally abundant, low cost, and have facile preparation, allowing scalable fabrication to fulfill the growing demand of susceptible sensor devices. Significant advances have been made in recent decades to design and fabricate various molybdenum oxides- and dichalcogenides-based sensing materials, though it is still challenging to achieve high performances. Therefore, many experimental and theoretical investigations have been devoted to exploring suitable approaches which can significantly enhance their gas sensing properties. This review comprehensively examines recent advanced strategies to improve the nanostructured molybdenum-based material performance for detecting harmful pollutants, dangerous gases, or even exhaled breath monitoring. The summary and future challenges to advance their gas sensing performances will also be presented.


2019 ◽  
Vol 21 (2) ◽  
pp. 162
Author(s):  
Nurul Fajriah

This article is a study of literature describing religious harmony: the relevance of Article 25 of the Medina Charter and Article 29 of the 1945 Constitution. The Medina Charter was made in the 7th century (classical century) and Article 29 of the 1945 Constitution was born in modern times, around the 20th century. Both have relevancy which states that every citizen is free to adhere to their respective religions. The plurality of society in Indonesia has similarities and differences from the plurality of society in Medina around 622 AD. The stability and harmony of religious communities in the Medina at that time was regulated in the Medina charter which is the constitution of the Medina state. Harmony among religious communities in Indonesia is also an important concern of the Indonesian government as stipulated in Article 29 of the 1945 Constitution. Freedom of religion is guaranteed by the state because the state believes that religious diversity is not a disintegrating factor for the Indonesian people.Abstrak: Artikel ini adalah kajian literatur yang mendeskripsikan kerukunan umat beragama: relevansi pasal 25 Piagam Madinah dan Pasal 29 UUD 1945. Piagam Madinah dibuat pada abad VII (abad klasik) dan pasal 29 UUD 1945 baru lahir pada zaman modern, sekitar abad XX. Keduanya memiliki relevansi yang menyatakan bahwa setiap warga negara bebas menganut agamanya masing-masing. Kemajemukan masyarakat di Indonesia mempunyai sisi-sisi persamaan dan perbedaan dengan kemajemukan masyarakat di Madinah sekitar tahun 622 M. Keberlangsungan dan keharmonisan umat beragama di negara Madinah pada waktu itu diatur dalam piagam Madinah yang merupakan konstitusi negara Madinah. Kerukunan antar umat beragama di Indonesia juga menjadi perhatian penting pemerintah dengan adanya kebijakan Negara Republik Indonesia dari segi agama yang tertuang dalam pasal 29 UUD 1945. Kebebasan beragama ini dijamin oleh negara karena keyakinan bahwa keberagaman agama tidak akan menjadi disentegrating factor bagi bangsa Indonesia


Author(s):  
Sinan Kaya

The purpose of this chapter is, as a self-regulated learning tool, to focus on digital storytelling by uncovering relationship between digital storytelling and self-regulated learning process/based on research findings made in the its field. Within this focus, firstly, concept of digital storytelling was theoretically addressed; researches made in learning-teaching for use have been presented; later, self-regulated learning processes and strategies have been defined and given examples. Finally, research findings on the use of digital stories as self-regulated learning tools have been shared.


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