Investigating submerged morphologies by means of the low-budget “GeoDive” method (high resolution for detailed 3D reconstruction and related measurements)

Geophysical methods allow to collect geological data on lake and sea bottoms and characterize large areas, even at high depths, but with high costs. Moreover, the most widespread acquisition methods for morpho-bathymetric survey and the related instruments used are almost always ship-, ROV- or AUV-based and consequently they require high budgets. It is known that shallow waters can represent a limit for certain vessels and techniques, preventing the acquisition in the shoreface zone. To overcome the limits, i.e. to survey with high accuracy nearshore shallow waters with a low budget, we tested and tuned the “GeoDive” method that allowed us to survey two test sites, featured by the presence of “block fields” (i.e., accumulations of huge blocks and boulders of gravitational origin) under shallow waters. The “GeoDive” method allowed us to map the submerged morphologies and to acquire high-resolution optical images for further photogrammetric processing. The latter was fundamental to obtain 3D high-resolution models, also with conditions of low visibility. An Action Sport Cam with high definition resolution has been used for video acquisition, in addition to the equipment used during scientific diving. By coupling the processing of underwater-acquired data with the direct surveys performed by underwater SCUBA operators, it was possible to perform some morphological and sedimentological measurements and observations on the experimental targets, with the help of suitable markers

Fatigue Damage Identification by a Global-Local Integrated Procedure for Truss-Like Steel Bridges

Civil steel structures and infrastructures, such as truss railway bridges, are often subject to potential damage, mainly due to fatigue phenomena and corrosion. Terefore, damage detection algorithms should be designed and appropriately implemented to increase their structural health. Today, the vast amount of information provided by data processing techniques and measurements coming from a monitoring system constitutes a possible tool for damage identifcation in terms of both detection and description. For this reason, the research activity aims to develop a methodology for a preliminary description of the damage in steel railway bridges induced by fatigue phenomena. Te proposed approach is developed through an integration of global and local pro cedures. At the global scale, vibration-based procedures will be applied to improve a forecast numerical model and, subsequently, to identify the zones most involved in fatigue problems. At the local scale, careful and refned local identifcation will be pursued via image processing techniques whose evidence will be analyzed and described through nonlinear numerical models. A case study of a historical railway bridge in Spain will illustrate the methodology’s performance, potentiality, and critical issue

Experimental Demonstration of Vibration Sensing and Positioning on Multiple Metropolitan Fibers

We investigate on simultaneous polarization sensing on multiple fibers to detect and time-position anomalous vibration events. We experimentally demonstrate that our “threshold and cross-correlate” algorithm obtains timing with 40 ms rms accuracy when tested on deployed fibers (35km and 10km) in Turin urban area

Asymmetric Effects of Luminance and Chrominance in the Watercolor Illusion

When bounded by a line of sufficient contrast, the desaturated hue of a colored line will spread over an enclosed area, an effect known as the watercolor illusion. The contrast of the two lines can be in luminance, chromaticity, or a combination of both. The effect is most salient when the enclosing line has greater contrast with the background than the line that induces the spreading color. In most prior experiments with watercolor spreading, the luminance of both lines has been lower than the background. An achromatic version of the illusion exists where a dark line will spread while being bounded by either a darker or brighter line. In a previous study we measured the strength of the watercolor effect in which the colored inducing line was isoluminant to the background, and found an illusion for both brighter and darker achromatic outer contours. We also found the strength of spreading is stronger for bluish (+S cone input) colors compared to yellowish (-S cone input) ones, when bounded by a dark line. The current study set out to measure the hue dependence of the watercolor illusion when inducing colors are flanked with brighter (increment) as opposed to darker outer lines. The asymmetry in the watercolor effect with S cone input was enhanced when the inducing contrast was an increment rather than a decrement. Further experiments explored the relationship between the perceived contrast of these chromatic lines when paired with luminance increments and decrements and revealed that the perceived contrast of luminance increments and decrements is dependent on which isoluminant color they are paired with. In addition to known hue asymmetries in the watercolor illusion there are asymmetries between luminance increments and decrements that are also hue dependent. These latter asymmetries may be related to the perceived contrast of the hue/luminance parings

Una procedura per l’identificazione del danno in strutture reticolari in acciaio

Come tutte le altre strutture, anche i ponti ferroviari in acciaio sono suscettibili di potenziale danneggiamento, dovuto principalmente a fenomeni di fatica e corrosione. Al fine di aumentare la sicurezza di tali infrastrutture, è utile identificare i danni esistenti così da poter intervenire prontamente. La quantità di dati a disposizione forniti dai sistemi di monitoraggio evidenzia la necessità di adottare metodologie opportune per l’identificazione del danno e la descrizione dei suoi effetti sul comportamento strutturale e sulla valutazione dell’affidabilità dell’opera. La tesi si pone l’obiettivo di individuare una metodologia in grado di utilizzare misure di vibrazione ed immagini. Per l’identificazione del danno attraverso misure di vibrazione si introduce un approccio basato su un funzionale di errore fra dati stimati da modello e quelli determinati dalle misure. In questo ambito i dati utilizzati sono le frequenze e le forme modali. Nel caso delle immagini si introduce un funzionale di errore fra descrittori del danno quali l’area plasticizzata o la cricca osservabili in modelli numerici locali di dettaglio e l’osservazione attraverso immagini digitali dello stesso fenomeno. Il modello locale è utilizzato per alimentare la scelta dei descrittori del danno nei modelli globali. Il metodo e le elaborazioni numeriche sono effettuati attraverso dati sperimentali forniti da una campagna sperimentale e di monitoraggio effettuata su un ponte ferroviario storico in Spagna

An integrated vibration-image procedure for damage identification in steel trusses

The paper deals with structural damage identification in steel trusses. Classical procedure based on dynamic measurements able to detect flexibility changes are complemented with data predicting cracks and their evaluating by image processing. The procedure proposes first a damage index, the Stiffness Reduction Factor (SRF), evaluated on the basis of the error between the predictive truss model and the experimental modal model. Then, a nonlinear FEM model is used to determine fatigue cracks in the truss nodes which are compared with the observed ones determined by image processing. A real case study, the Quisi bridge located in Spain, is used to show the potentiality of the procedure

ACUTE EFFECTS OF WHOLE-BODY VIBRATION ON KNEE JOINT DROP LANDING KINEMATICS AND DYNAMIC POSTURAL STABILITY

Whole-body vibration (WBV) is being increasingly utilized in addition to other training modalities in order to prevent and rehabilitate athletic injuries. Excessive knee joint movement has been reported to be a contributing factor to many traumatic and overuse knee joint injuries (Sigward et al., 2008). However the effects of WBV on sensorimotor function and consequent knee joint kinematics is unknown. Thus, the aim of the present study was to examine the effects of an acute WBV exposure on knee joint drop landing kinematics and dynamic postural stability in healthy participants. The null hypothesis was that acute WBV exposure would not influence lower limb drop landing kinematics or dynamic postural stability

Optimization of capsaicin acylase production from Streptomyces mobaraensis in bench-top fermenter

Capsaicin, the major pungent principle in hot pepper fruit, can be hydrolyzed enzymatically to vanillylamine (a natural precursor of vanillin) using a specific acylase from Streptomyces mobaraensis. Production of this enzyme using strain DSM40847 was studied under batch fermentation conditions in stirred tank (STR) and airlift (AR) bioreactors. The process performance in both fermentation devices was different with respect to biomass, enzyme concentration and specific yield (enzyme activity/biomass content); in particular the specific yield was lower in the AR (5.7 mU/g of biomass) than in the STR (6.25 mU/g of biomass). Experiments carried out in STR bioreactors at controlled (DO = 20% of saturation) and uncontrolled dissolved oxygen concentration, and at constant stirrer speeds (300, 450 and 600 rpm) demonstrated that the DO level has no remarkable effect on the production of the capsaicin-hydrolyzing enzyme, which is mainly produced in a cell-associated

Screening, isolation, and characterization of glycosyl-hydrolase-producing fungi from desert halophyte plants

Fungal strains naturally occurring on the wood and leaves of the salt-excreting desert tree Tamarix were isolated and characterized for their ability to produce cellulose- and starch- degrading enzymes. Of the 100 isolates, six fungal species were identified by ITS1 sequence analysis. No significant differences were observed among taxa isolated from wood samples of different Tamarix species, while highly salt-tolerant forms related to the genus Scopulariopsis (an anamorphic ascomycete) occurred only on the phylloplane of T. aphylla. All strains had cellulase and amylase activities, but the production of these enzymes was highest in strain D, a Schizophyllum-commune- related form. This strain, when grown on pretreated Tamarix biomass, produced an enzymatic complex containing levels of filter paperase (414 ± 16 IU/ml) that were higher than those of other S. commune strains. The enzyme complex was used to hydrolyze different lignocellulosic substrates, resulting in a saccharification rate of pretreated milk thistle (73.5 ± 1.2 %) that was only 10 % lower than that obtained with commercial cellulases. Our results support the use of Tamarix biomass as a useful source of cellulolytic and amylolytic fungi and as a good feedstock for the economical production of commercially relevant cellulases and amylases. [Int Microbiol 2014; 17(1):41-48]Keywords: Schizophyllum commune · Tamarix ssp. · cellulase activity · amylase activit