1,720,976 research outputs found
Experimental system to determine the start of fracture propagation during impact test
No full textThis work explains the sep-up of a fully automated method for the measurement of the fatigue threshold with an exponentially decreasing of the applied stress intensity factor
Studio del contatto bronzo-acciaio in condizioni di strisciamento nel settore delle macchine automatiche (Bronze-steel sliding contact in packaging applications)
No full textLo studio condotto è dedicato a componenti di macchine automatiche per la pressatura di polveri ad uso farmaceutico o alimentare, sottoposti ad un contatto tribologico non conforme di strisciamento in condizioni di lubrificazione limite. Il tribosistema studiato comprende due elementi: punzoni in acciaio da utensili X100CrMoV5 e camme in bronzo all’alluminio G-CuAl11Fe4Ni4. Nella fase iniziale dello studio sono stati identificati i meccanismi di usura prevalenti nel tribosistema reale avvalendosi di tecniche standard di failure analysis, mentre nella seconda fase sono state eseguite prove di strisciamento su scala di laboratorio. Nelle prove tribologiche di laboratorio, il coefficiente di attrito è risultato indipendente dalle condizioni di trattamento termico del bronzo, mentre si è rilevata una significativa dipendenza da carico normale e velocità. L’usura del bronzo è risulta principalmente influenzata dalla sua capacità di incrudimento e/o di formare e stabilizzare uno strato protettivo superficiale a base di ossidi di rame, al variare delle condizioni di trattamento termico e dei parametri operativi del moto
A simple and industrially scalable method for making a PANI-modified cellulose touch sensor.
No full textA simple and industrially scalable method for making a PANI-modified cellulose touch sensor.
Ragazzini a, I. Gualandi a, *, S. Selli b, C. Polizzi a, M.C. Cassani a, D. Nanni a, F. Gambassi a, F. Tarterini a, D. Tonelli a, E. Scavetta a, B. Ballarin a, *
a Department of Industrial Chemistry “Toso Montanari”, Bologna University, Viale Risorgimento 4, I-40136, Bologna, Italy; b Cromatos s.r.l., via G. Cardano, 6B/C/D, 47122, Forlì, Italy
Nowadays, alternatives to the traditional electronics that should be low cost, degradable, compostable and made from environmentally nontoxic substances are of great interest in research. As candidate, we propose bare fibers of cellulose made conductive by an in situ oxidative polymerization of aniline. The resulting composite fibers were emplojed to fabricate electroactive sheets using a pilot plant of a typical paper industry. The resistivity of the obtained sheets is 14 ± 1 Ω sq-1, a value around 1000 times lower than those reported in literature. The higher electronic performances of the sheets were demonstrated by assembling a capacitive touch sensor device with optimized geometry. The touch sensor shows an increase of 3–4 % of the starting electric capacity after compression and a fast response time of 52 ms. To our knowledge this is the first time that a device is prepared in this way and therefore, the herein presented results can bring a significant improvement in the development of low-cost, green and high-tech electronic devices 1.
[1] Ragazzini, I. et al. A simple and industrially scalable method for making a PANI-modified cellulose touch sensor. Carbohydr. Polym. (2020) doi: 10.1016/j.carbpol.2020.117304
PEO layers obtained from mixed aluminate–phosphate baths on Ti–6Al–4V: Dry sliding behaviour and influence of a PTFE topcoat
No full textThe present study focuses on the influence of PEO treatments (performed in the AC regime using mixed aluminate–phosphate baths) on the tribological behaviour of Ti–6Al–4V, dry sliding against EN100Cr6 steel. Three different sets of coatings were produced: (set 1) in an aluminate-rich electrolyte; (set 2) in
a phosphate-rich electrolyte; and (set 3) identical to set 2, but with the addition of a spray-deposited PTFE topcoat. The topography, microstructure, phase constitution and surface microhardness of each set were characterized and dry sliding tests were carried out in the load range 5–120N using a block-on-ring tribometer. For each set, a transition load which corresponds to the end of coating life has been identified. The highest transition loads were observed for coatings produced using the aluminate-rich electrolyte (set 1). Intermediate values of transition load were measured for duplex PTFE/PEO coatings (set 3). Single-layer PEO coatings produced in the phosphate-rich electrolyte (set 2) showed the lowest
values of transition load, due to the low coating thickness and poor uniformity. The deposition of the PTFE topcoat proved to be beneficial in terms of both friction and wear resistance, particularly in an intermediate (30–50 N) load range
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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