Process noise covariance estimation via stochastic approximation

Kalman filtering for linear systems is known to provide the minimum variance estimation error, under the assumption that the model dynamics is known. While many system identification tools are available for computing the system matrices from experimental data, estimating the statistics of the output and process noises is still an open problem. Correlation-based approaches are very fast and sufficiently accurate, but there are typically restrictions on the number of noise covariance elements that can be estimated. On the other hand, maximum likelihood methods estimate all elements with high accuracy, but they are computationally expensive, and they require the use of external optimization solvers. In this paper, we propose an alternative solution, tailored for process noise covariance estimation and based on stochastic approximation and gradient-free optimization, that provides a good trade-off in terms of performance and computational load, and is also easy to implement. The effectiveness of the method as compared to the state of the art is shown on a number of recently proposed benchmark examples.     

Ocular movements under taskload manipulations: Influence of geometry on saccades in air traffic control simulated tasks

Traffic geometry is a factor that contributes to cognitive complexity in air traffic control. In conflict‐detection tasks, geometry can affect the attentional effort necessary to correctly perceive and interpret the situation; online measures of situational workload are therefore highly desirable. In this study, we explored whether saccadic movements vary with changes in geometry. We created simple scenarios with two aircraft and simulated a conflict detection task. Independent variables were the conflict angle and the distance to convergence point. We hypothesized lower saccadic peak velocity (and longer duration) for increasing complexity, that is, for increasing conflict angles and for different distances to convergence point. Response times varied accordingly with task complexity. Concerning saccades, there was a decrease of peak velocity (and a related increase of duration) for increased geometry complexity for large saccades (>15°). The data therefore suggest that geometry is able to influence “reaching” saccades and not “fixation” saccades. © 2011 Wiley Periodicals, Inc.     

Untersuchung des Datenverkehrs aktueller Smart-TVs

Das Internet der Dinge (IoT) bezeichnet die Anbindung von Gegenständen des alltäglichen Gebrauchs an das Internet. Der Fernseher ist als Smart-TV bereits Teil des Internets. Einige Untersuchungen haben hier in jüngster Vergangenheit deutliche Missstände in Bezug auf Datenschutz und Datensicherheit aufgezeigt. Der Beitrag fasst die Ergebnisse einer aktuellen, umfangreichen Untersuchung von fünf Smart-TVs zusammen.     

Double actuation architectures for rendering variable impedance in compliant robots: A review

Novel compliant actuation systems have been developed in recent years for a variety of possible advantages, such as establishing a safe human–robot interaction, increasing energy efficiency, reducing the effects of impacts and even for the development of neuro-inspired robotic platforms to be used in human motor control studies.In this rapidly growing and transversal research field, systems involving more than one active element (typically motors) for each actuated degree of freedom are being investigated to allow separate position and impedance regulations. Considering the wide range of applications and the large number of different arrangements deriving from the combination of two active elements and passive elastic components, several actuation architectures have been devised.This paper reviews state-of-the-art rotary variable impedance units incorporating two separate motors. Existing devices are grouped in three main categories. A critical and comparative analysis of the most relevant features is carried out, also based on most representative prototypes. Recently proposed methodologies and evaluation criteria for design optimization are illustrated and perspectives on potential applications of double actuation systems are presented.     

Effects of saline stress on mineral composition,phenolic acids and flavonoids in leaves of artichoke and cardoon genotypes grown in floating system

BACKGROUND: Cynara cardunculus is a species native to the Mediterranean basin. It includes globe artichoke and cultivated cardoon as well as their progenitor wild cardoon. The species is a source of biophenols, and its leaf extracts have been widely used in herbal medicine as hepatoprotectors and choleretics since ancient times. The aim of this study was to determine the effect of increasing the level of salinity in the nutrient solution (1 or 30 mmol L^?1 NaCl) on biomass production, mineral composition, radical‐scavenging activity, caffeoylquinic acids and flavonoids in three artichoke (‘Romolo’, ‘Violetto di Provenza’ and ‘Violetto di Romagna’) and three cultivated cardoon (‘Bianco Avorio’, ‘Bianco Gigante Inerme’ and ‘Gigante di Romagna’) cultivars grown in a floating system. RESULTS: Increased salinity in the nutrient solution decreased the leaf dry biomass and leaf number of artichoke and cultivated cardoon cultivars. Salinity reduced macro‐ and microelement accumulation in leaves (e.g. N, K, Ca, Mg, Fe, Mn and B) but improved their antioxidant activity, total polyphenols, chlorogenic acid, cynarin and luteolin. The cultivated cardoons, especially ‘Bianco Avorio’ and ‘Gigante di Romagna’, showed higher biomass and leaf number than those observed in artichoke genotypes. ‘Violetto di Provenza’ exhibited the highest content of chlorogenic acid, closely followed by ‘Violetto di Romagna’, whereas for cynarin content the highest values were recorded in ‘Violetto di Provenza’, ‘Bianco Avorio’ and ‘Gigante di Romagna’. The highest content of luteolin was recorded in ‘Gigante di Romagna’ and ‘Bianco Avorio’, while the highest content of apigenin was observed in ‘Gigante di Romagna’. CONCLUSION: The results showed that the floating system could be considered an effective tool to improve quality aspects through proper management of the salt concentration in the nutrient solution. They also suggest that specific cultivars should be selected to obtain the desired profile of bioactive compounds. © 2012 Society of Chemical Industry     

Simulation of retronasal aroma of white and red wine in a model mouth system. Investigating the influence of saliva on volatile compound concentrations

The influence of saliva on aroma release from white and red wines was studied in a model mouth system. Aroma compounds were analysed in the dynamic headspace of wines by solid phase micro extraction/gas chromatography with flame ionization detection. Volatile compounds were identified by solid phase micro extraction/gas chromatography-mass spectrometry, resulting in a total of 43 compounds in white wine and 41 in red wine. The results showed a greater influence of saliva on aroma release in white wine than red wine. In white wine treated with human saliva, esters and fusel alcohols, responsible for fruity and fusel oil odours, were reduced of 32–80%; by contrast, the concentration of 2-phenylethanol and furfural, responsible for rose and toasted almond notes, increased by 27% and by 155%, respectively. In red wine, treated with human saliva, only a few esters decrease, with a reduction of 22–51% due to protein-binding ability of polyphenols that are able to inhibit the activity of the saliva. C-13 norisoprenoids, vitispirane (eucalyptol) and TDN (kerosene), decreased both in white and red wine, showing a comparable variation while, for β-damascenone, the variation was insignificant.     

Application of the dry‐spinning method to produce poly(ε‐caprolactone) fibers containing bovine serum albumin laden gelatin nanoparticles

We designed and manufactured a polymeric system with combined hydrophilic–hydrophobic properties by loading gelatin nanoparticles (GNPs) containing bovine serum albumin (BSA) into poly(ε‐caprolactone) (PCL) fibers. Our ultimate goal was to create a device capable of carrying and releasing protein drugs. Such a system could find several biomedical applications, such as those in controlled release systems, surgical sutures, and bioactive scaffolds for tissue engineering. A two‐step desolvation method was used to produce GNPs, whereas PCL fibers were produced by a dry‐spinning method. The morphological, mechanical, and thermal properties of the produced system were investigated, and the distribution of nanoparticles both inside and on the surface of the fibers was examined. The effect of the particles on the biodegradability of the fibers was also evaluated. In vitro preliminary tests were performed to study the release of BSA from nanoparticle‐laden fibers and to compare this with its release from free nanoparticles. Our results indicate that the distribution of particles inside the fibers was quite homogeneous and only a few of them were present on the surface. The presence of the particles in the fibers did not affect the thermal properties of the PCL polymer matrix, although it created voids that affected the degradation characteristics so the PCL fibers favored faster erosion compared to the plain fibers. Preliminary results indicate that the release from GNP‐laden fibers occurred much more slowly compared to that in the free GNPs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44233.     

Morphology modulation of gas‐foamed,micrometric, hollow polystyrene particles

In this article, we reports the effects of the processing conditions on the morphological and hollow attributes of polystyrene micrometric hollow particles produced by the use of a recently developed technique based on the gas foaming of spherical, dense particles. By modulating the foaming temperature and saturation pressure, we produced hollow particles with different attributes in terms of hollow dimensions, eccentricity, and open–close features. The results from these small systems were compared, and we found agreement with what is typically observed in bulk polymeric foaming, for example, an increase in the foaming efficiency with saturation pressure and the nonmonotonic effect of temperature. Furthermore, we observed an increase in the hollow number when using nucleating agents with respect to the neat polymer and when using nitrogen with respect to carbon dioxide as the blowing agent. The effects of particle manipulation before foaming to achieve hollow elongated or distorted particles are also reported. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44236.