1,720,992 research outputs found
Modeling Electronic Skin Response to Normal Distributed Force
No full textThe reference electronic skin is a sensor array based on PVDF (Polyvinylidene fluoride) piezoelectric polymers, coupled to a rigid substrate and covered by an elastomer layer. It is first evaluated how a distributed normal force (Hertzian distribution) is transmitted to an extended PVDF sensor through the elastomer layer. A simplified approach based on Boussinesq’s half-space assumption is used to get a qualitative picture and extensive FEM simulations allow determination of the quantitative response for the actual finite elastomer layer. The ultimate use of the present model is to estimate the electrical sensor output from a measure of a basic mechanical action at the skin surface. However this requires that the PVDF piezoelectric coefficient be known a-priori. This was not the case in the present investigation. However, the numerical model has been used to fit experimental data from a real skin prototype and to estimate the sensor piezoelectric coefficient. It turned out that this value depends on the preload and decreases as a result of PVDF aging and fatigue. This framework contains all the fundamental ingredients of a fully predictive model, suggesting a number of future developments potentially useful for skin design and validation of the fabrication technology
Model-based approach for indentation on soft electronic skin
No full textThe primary objective of this research is to develop a model-based framework for the indentation on the surface of a soft electronic skin. In the current paper, the model has been applied to a soft electronic skin embedding piezoelectric polymer (PVDF, polyvinylidene fluoride) transducers. We revisit in a dimensionless fashion an analytical solution of the problem presented in a previous contribution for a normal force (frictionless case) and extend the analysis to account for a tangential component of the contact force (frictional case). First, the transmission of Hertzian distributed forces through the skin elastomer layer to a PVDF transducer is analyzed, assuming a half-space model for the elastomer. Then, the above mathematical formulation has been employed to perform extensive FEM simulations such to extend the analytical solutions for the half-space case to the real configuration where the elastomer layer has finite thickness and the transducer is not necessarily vertically aligned with the indenter. The model is applied to the case of a dragon skin, a well-known soft alternative to the silicone-based PDMS e-skin discussed in the previous paper. The model can be easily extended to other sensor types, provided the transducer is integrated on a rigid substrate and converts the pressure acting on its upper surface into a proportional electrical signal. The present framework is a first step towards the construction of a general design tool for soft electronic skins based on pressure transducers, regardless of the specific transducer type and material employed for the soft cover
Águila, G., Luciani, L., Seminara, L. y Viano, C. (Comps.) (2018). La historia reciente en Argentina. Balances de una historiografía pionera en América Latina. 1 edición. Imago Mundi: Buenos Aires 304 Páginas
No full textÁGUILA, G., LUCIANI, L., SEMINARA, L. y VIANO, C. (Comps.) (2018). La historia reciente en Argentina. Balances de una historiografía pionera en América Latina. 1 edición. Imago Mundi: Buenos Aires 304 Páginas
The Development of Deep and Short Sea Shipping Container Routes Departing from Italian Ports / Razvoj obalnih i prekooceanskih pomorskih kontejnerskih ruta koje kreću iz talijanskih luka
Full text linkIn this paper, an analysis of the development of Deep Sea Shipping (DSS) and Short Sea Shipping (SSS) container routes calling at Italian ports, is carried out. Data about DSS routes have been collected in the years: 2011, 2014, 2018 and 2019, while data about SSS services have been collected in 2010 and 2018. Italian ports have been classified as follows: Ligurian multi-port gateway cluster, which is formed by Leghorn, La Spezia, Genoa, Savona/Vado Ligure; Northern Adriatic multi-port gateway cluster, made up of Ancona, Ravenna, Venice and Trieste; Campanian multi-port gateway cluster, composed of Naples and Salerno; hub ports, i.e. Gioia Tauro, Cagliari (only until 2018) and Taranto (only until 2014). The most important gateway cluster, for both DSS and SSS services, is the Ligurian one which includes Genoa which is by far the major Italian container gateway port. Genoa has shown an almost constant increase in container traffic in the time period analyzed. Italian hub ports are also an important group, but they have registered a negative trend in the years under analysis. DSS routes, to Far East and the American Continent, usually call at the Ligurian ports and the hub port of Gioia Tauro. Northern Adriatic ports are crossed by only a few DSS routes, but they are crossed by a large number of SSS routes, especially feeder ones, with transshipment mainly in the hub ports of Gioia Tauro, Marsaxlokk, Piraeus and Port Said. The evolution of DSS services shows clearly the effects of naval gigantism phenomenon: the number of DSS services has decreased, but the total and, especially, the average DWT have increased. As regards SSS routes, also their frequencies have decreased, but their length and, in particular, the number of ports called, have increased: this choice is performed by container operators in order to increase the ships ’load factor’
Validation of screen‐printed electronic skin based on piezoelectric polymer sensors
No full textThis paper proposes a validation method of the fabrication technology of a screen‐printed electronic skin based on polyvinylidene fluoride‐trifluoroethylene P(VDF‐TrFE) piezoelectric polymer sensors. This required researchers to insure, through non‐direct sensor characterization, that printed sensors were working as expected. For that, we adapted an existing model to non-destructively extract sensor behavior in pure compression (i.e., the d33 piezocoefficient) by indentation tests over the skin surface. Different skin patches, designed to sensorize a glove and a prosthetic hand (11 skin patches, 104 sensors), have been tested. Reproducibility of the sensor response and its dependence upon sensor position on the fabrication substrate were examined, highlighting the drawbacks of employing large A3‐sized substrates. The average value of d33 for all sensors was measured at incremental preloads (1–3 N). A systematic decrease has been checked for patches located at positions not affected by substrate shrinkage. In turn, sensor reproducibility and d33 adherence to literature values validated the e‐skin fabrication technology. To extend the predictable behavior to all skin patches and thus increase the number of working sensors, the size of the fabrication substrate is to be decreased in future skin fabrication. The tests also demonstrated the efficiency of the proposed method to characterize embedded sensors which are no more accessible for direct validation
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
Low power approximate multipliers for energy efficient data processing
No full textComputation accuracy can be adequately tuned on the specific application requirements in order to reduce power consumption. To give some examples, image processing and audio/speech recognition e.g., multimedia applications may provide more accurate outputs than human capabilities can appreciate. In this case, producing inexact numerical outputs can be acceptable and approximate computing circuits could be employed to reduce power consumption by decreasing the hardware complexity. This paper proposes approximate multipliers based on exact and inexact adder circuits and their FPGA implementation: the proposed multipliers can be applied for both signed and unsigned operations. Two scenarios were considered and analyzed in this paper. First, the performance of the proposed multiplier based on inexact adder is evaluated by comparing the power consumption, the accuracy of computation, and the time delay with those of an approximate multiplier based on exact adder. Second, the design parameters of the proposed multipliers are compared with those of the Baugh-Wooley multiplier. On the other hand, we analyzed and compared the performance of the unsigned approximate multipliers with respect to the signed approximate ones. Results prove that the proposed approximate multipliers achieve a reduction in power consumption of 56.3% with respect to the Baugh-Wooley multiplier at cost of less than 5% of accuracy loss
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
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