1,721,131 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Promaxon-D reinforced brake-pads to ameliorate the noise-vibration performance
No full textA synthetic hydrated calcium silicate (commercially available as Promaxon-D) is used as one of the ingredient in some friction materials (FMs) since it has the ability to improve the porosity of the product due to its very special crystalline structure. The present work aims to evaluate the detailed noise and vibration (NV) performance of Promaxon-D (PD) based pads in comparison with the non-PD based ones. Five different types of Cu-free brake-pads were developed with identical composition but varying wt.% of PD particles (0, 5, 10, 15, and 20) and compensating the difference with barite, a space filler. After characterizing these brake-pads for physical and mechanical properties, NV performance was evaluated following SAE J2521 test standard and also the friction-performance based on the data generated on the same rig. As the PD contents increased, the brake NV performance improved considerably for the selected operating conditions. In view of the overall improvement in both noise and vibration aspects, the pad with 20 wt.% PD (P20) performed best with an overall ~ 3 dBA drop in noise level and ~11% drop in vibration vis-à-vis PD-free pads leading to a conclusion that 20 wt.% PD may be used for improving the NV performance of brake-pads and also increasing the friction level
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Influence of increasing amount of attapulgite on the performance properties of Cu-free brake-pads
No full textCopper is almost inevitable functional filler in the brake-material and efforts to replace it are continuing since it is now known as a hazard to the aquatic life. It is always desirable to search for ingredients for Cu-free brake-pads, which will be beneficial for friction-related properties and especially fade resistance. Attapulgite, is a mineral which was proven to be an excellent substitute for asbestos in brake-pads long back. However, hardly anything in details is reported on its exact role in controlling tribo-properties of friction materials (FMs). It was of interest, if it can be helpful in enhancing the performance of Cu-free FMs. Hence, in this work a series of brake-pads (five types) was formulated and developed with increasing amount of attapulgite (0, 5, 10 and 15 wt. %) by compensating with inert barite particles in Cu-free FMs. The parent composition was fixed and instead of Cu powder, 10 wt.% stainless steel powder was used. One more type of pads was also developed containing Cu and attapulgite (10 wt. % each) just to compare its performance with that containing 10 % stainless steel powder and attapulgite, (10 wt. % each) keeping every other ingredients in parent composition as constant. The pads were characterised for physical, chemical and mechanical properties. The tribological characteristics were evaluated using full-scale inertia dynamometer as per JASO-C-406 standards under dry condition. The results revealed that the attapulgite exhibited slightly lubricating properties by reducing average μ with increasing amount. However, it helped to increase the wear resistance to small extent, but at the cost of deterioration in some beneficial properties such as fade resistance, fluctuations in μ. Overall, its inclusion in Cu-free brake-pads did not prove beneficial as expected
Argon low-pressure plasma treatment to stainless steel particles to augment the wear resistance of Cu-free brake-pads
No full textNowadays, the usage of Copper in brake friction materials (FMs)/pads is a major concern in the brake industry. Despite some of the earlier attempts for the Cu substitution, an issue with high wear of FMs due to their low adhesion of metal particles with the matrix (i.e., phenolic resin) is still largely unresolved. In the current study, the surface energy (SE) of stainless steels (SS316, SS410) and Cu particles was augmented using the right kind of plasma in optimized dose to improve the wettability/adhesion of metal particles with the matrix. The SE of treated particles increased significantly due to the reduction of oxides from the surfaces. A series of seven types of brake-pads was developed containing 3 vol% of SS and Cu (untreated and treated) particles as the theme ingredients keeping parent composition fixed. A reference pad without metal particles was also developed for benchmarking. The developed pads were characterized for physical properties and then evaluated for the tribological and noise-vibration (NV) performance on a brake-dynamometer following global test standards. The results revealed that the pads with treated SS and Cu particles showed a higher fade resistance (~ 2–3%) and reduced wear by ~ 10% compared to the pads with untreated particles. Overall, based on optimized technique, treated SS316 particles proved the best. The underlying mechanisms were studied through worn surface analysis using a field emission scanning electron microscope attached (FESEM) with an energy dispersive X-ray spectroscopy (EDAX)
Copper-free brake-pads: A break-through by selection of the right kind of stainless steel particles
No full textDevelopment of Copper-free friction materials (FMs) with an equivalent or better performance has been a focus of research from the last few years since the Cu-containing wear debris has been proven as a serious threat to the aquatic life. In this work, eco-friendly brake-pads were developed with various types of stainless steel particles (SSPs) to explore the possibility of replacing copper from the brake-pads. A series of six multi-ingredient brake-pads was developed containing 3 vol % SSPs (SS304, SS316, SS410 and SS434), SS swarf (SS434) and copper particles as theme ingredients keeping parent formulation identical. The brake-pads were characterized for physical, mechanical, chemical, and thermal properties. Tribo-performance was evaluated on a full-scale inertia brake-dynamometer by following JASO C406 test standard. Results revealed that almost all the properties were superior to the Cu-containing pads including wear. The average coefficient of friction was almost similar for all pads and wear performance was excellent for SS316 and SS304 based brake-pads since these materials had higher surface energy vis-à-vis the adhesion improvement with the matrix. Surface analysis of worn brake-pads was done using a scanning electron microscopy (SEM). Finally, overall performance ranking of the brake-pads was done by using ‘Multiple Objective Optimizations by Ratio Analysis’ (MOORA) method
Eco-friendly brake-pads using ferritic stainless-steel particles of varying sizes: Influence on performance properties
No full textMetallic particles in brake-friction materials (FMs) play a vital role in improving mainly strength, friction level, thermal conductivity and hence resistance to fade during braking operations. Although Copper was the most efficient and popular metallic ingredient in FMs, it is being phased out because of its proven threat to the aquatic life in the form of wear debris. Hardly any successful efforts are reported in open literature barring few on in the authors' laboratory. It is well-known that the size and shape of particles affect the performance of composites apart from their type, concentration, etc. In this paper, Ferritic stainless steel (SS 434) particles were selected as a theme ingredient in two forms, first particulate (SSP) with two sizes, larger (30-45 micron) and smaller (10-20 micron) and also in the form of swarf. The aim was to investigate the size and shape effect of these ingredients when used to manufacture the brake-pads on the performance properties. A series of three multi-ingredient brake-pads with identical composition but differing in the type of SS particles and swarf. The theme ingredients were SS 434 particles (10-20 and 30-45 micron) and SS 434 swarf (Length:1-2 mm, diameter-50 micron). The developed brake-pads were characterised for physical, mechanical, chemical and thermal properties as per standards. Tribological performance was evaluated on full-scale inertia dynamometer by following JASO C406 standards. Results indicated that most of the tribological properties best for pads with smaller sized SSPs and the poorest with swarf (SSS). The topography of worn brake-pads was studied using a scanning electron microscopy (SEM). Finally, overall performance was analyzed by using the âMultiple Objective Optimizations by Ratio Analysis (MOORA) technique.
Role of promaxon-d in controlling tribological performance of cu-free brake pads
Full text linkCopper appears to be an indispensable ingredient of non-asbestos organic (NAO) brake friction materials owing to its multifunctionality. However, recent findings proved it as a threat to aquatic life and efforts were initiated worldwide over the last few years to find a substitute for it. Recently, the authors’ group had reported on the potential of particulate Promaxon-D (hydrated calcium silicate), a porous material for enhancement of noise–vibration (NV) performance of Cu-free brake pads. It was felt necessary to investigate how Promaxon-D (PD) contributes to controlling tribo-performance of brake pads since this aspect is most important for the brake friction materials. A series of five types of brake pads was developed by keeping parent composition fixed and varying the theme ingredient PD content from 0–20 wt.%. The tribo-performance was evaluated on a full-scale brake inertia dynamometer as per the JASO C406 test standards. The increase in PD contents led to a reduction in density, hardness, and thermal conductivity while an increase in porosity and compressibility. With the increase in PD contents, almost all tribo properties such as average μ, fade ratio, and recovery ratio got enhanced, sensitivity of μ for pressure, speed, and temperature lowered but at the cost of wear resistance. Finally, the worn surfaces of pads and discs were observed under a scanning electron microscope equipped with energy dispersive X-ray (SEM-EDX) to find out the presence of various elements at the contact zone and to monitor specific topographical events responsible for wear mechanism
- …
