1,720,970 research outputs found
Instantaneous Angular Speed Analysis, Measurement Errors and Signal Filtering
No full textRecently, Instantaneous Angular Speed (IAS) is becoming an interesting measurement solution for condition monitoring of rotating machines. Various researchers are studying the measurement’s limits, new signal processing methods and new industrial applications. In Spagnol et al. (Proceedings of COMADEM2013, 2003) [1], IAS is compared to Torsional Laser Vibrometer (TVM) and to acceleration data. IAS is less affected by noise if compared with TVM and it is very informative in respect to acceleration. The current work focuses on the estimation of the IAS through the Elapsed Time (ET) method, using a counter to measure the time elapsed between the pulses of an encoder. From the variation of the IAS during the machine loads’ cycle it is possible to identify defects and faults. The data is acquired from an experimental test rig specifically designed for IAS evaluation. The setup is composed of an asynchronous four poles electric motor driven by a 380V 50Hz line current, a bearings’ test group and a variable brake system simulating different loads’ conditions. The paper reports on the results obtained with different data processing techniques and filtering approaches. The combined effect of the errors generated by the counter and the speed variation of the machines will be analyzed and commented, showing the advantages and drawbacks of the adopted IAS measurement
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
Optimisation by Evolutionary Algorithms of Free-Layer Damping Treatments on Plates
No full textThe problem of controlling or reducing vibration levels is very common in many different applications. From costly aeroplane fuselages to cheap domestic appliances the prob- lem can be tackled with the appropriate use of free layer damping treatments (FLDT).1 This technique, based on the distribution of layers of visoelastic material on the vibrating parts, is frequently adopted since it is cheap, efficient and easily applicable either at the design stage or in situ as a cor- rective measure. Due to these advantages and few limitations, not much care is taken to optimise the material distribution. Conversely, the necessity to produce lighter and quieter products will force the designer to optimise these treatments too. Under these circumstances, the most appropriate optimi- sation objectives seem to be the maximisation of the achiev- able damping levels and the minimisation of the amount of added material. In this work the potential of the genetic algorithm for the determination of th
An enquiry into the causes of an explosion accident occurred in a biogas plant
Full text linkBiogas is a versatile carrier of renewable energy produced by means of the digestion of crops, residues, or other wastes, and storage of the gas in dedicated plants. Safety regulations impose operational and technical restrictions to areas interested by the presence of the biogas in order to limit the explosion risk. Conversely, other areas of the plant are not subject to strict safety requirements. Nevertheless, explosions can be triggered in these areas as well, as the present investigation confirms. In the specific case, the production of biogas by anaerobic digestion in a storm‐water tank and its infiltration and accumulation into a technical building through a pipe connection caused the explosion of the building itself. The authors describe the procedures adopted for the enquiry and suggest possible improvements to the safety regulations for biogas plants
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
- …
