A Koszul Decomposition for the Computation of Linear Syzygies

In the present paper some algorithms are proposed for computing Linear Strands and Betti Numbers of graded modules over polynomial rings. These algorithms are based on a block-decomposition, induced by the Koszul syzygies, of the linear systems involved with the Hilbert's method for computing syzygies. Some further optimizations are suggested and applied by the authors to an implementation they have developed of the algorithms. Received: January 10, 2000; revised version: July 17, 2000     

A vision system for symbolic interpretation of dynamic scenes using arsom

We describe an artificial high-level vision system for the symbolic interpretation of data coming from a video camera that acquires the image sequences of moving scenes. The system is based on ARSOM neural networks that learn to generate the perception-grounded predicates obtained by image sequences. The ARSOM neural networks also provide a three-dimensional estimation of the movements of the relevant objects in the scene. The vision system has been employed in two scenarios: the monitoring of a robotic arm suitable for space operations, and the surveillance of an electronic data processing (EDP) center.     

Analysis of the behaviour of a 4-stroke Si engine fuelled with ammonia and hydrogen

The use of hydrogen as fuel represents a possible solution to reduce greenhouse gas emission from vehicles. Although proper engine running with hydrogen has been widely demonstrated, hydrogen storage onboard of the vehicle is a major problem.     

FALDOI: A New Minimization Strategy for Large Displacement Variational Optical Flow

We propose a large displacement optical flow method that introduces a new strategy to compute a good local minimum of any optical flow energy functional. The method requires a given set of discrete matches, which can be extremely sparse, and an energy functional which locally guides the interpolation from those matches. In particular, the matches are used to guide a structured coordinate descent of the energy functional around these keypoints. It results in a two-step minimization method at the finest scale which is very robust to the inevitable outliers of the sparse matcher and able to capture large displacements of small objects. Its benefits over other variational methods that also rely on a set of sparse matches are its robustness against very few matches, high levels of noise, and outliers. We validate our proposal using several optical flow variational models. The results consistently outperform the coarse-to-fine approaches and achieve good qualitative and quantitative performance on the standard optical flow benchmarks.     

Creep behavior of high density polyethylene after aging in contact with different oil derivates

The creep behavior of a high density polyethylene (HDPE), currently used as raw material for pipe manufacture, was evaluated before and after exposure to oil derivates using transient rheometry. The creep behavior of the original HDPE was satisfactorily described using a generalized Kelvin‐Voigt model based on two retardation times. The values of these critical times were quite different from each other, indicating a large distribution of macromolecular weight. The aging procedure was performed by immersing the polymer in two model fluids chosen to discriminate and understand the action of aromatic and paraffinic fractions of fuel derivatives (white oil, gas‐oil). The batch operation was also carried out at two different temperatures to investigate the thermal activation of plausible degrading mechanisms. In the case of the aging performed in the paraffinic fluid, the polymer compliance continuously increased with the immersion duration. This behavior was attributed to a plasticization induced by the diffusion of the liquid in the polymer matrix. The same phenomenon was observed in the early stage of the HDPE aging carried out with the aromatic fluid. However, for longer aging times, the extraction of low molecular weight species produced the stiffening of the thermoplastic. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Dielectric Tunability of DNA Biopolymer Films with Varying Amounts of Hexadecyltrimethylammonium Chloride

Deoxyribonucleic acid (DNA) biopolymer films are fabricated with varying amounts of hexadecyltrimethylammonium chloride (CTMA), which is a surfactant necessary to produce a DNA complex that is soluble in organic solvents. The dielectric constant (κ) of these films at microwave frequencies as a function of applied static electric field (E _DC) is investigated. Results show that the dependence of κ on E _DC, which is referred to as the dielectric tunability, is influenced by the amount of CTMA in the complex. Dielectric tunability is suppressed when the amount of CTMA is insufficient and improved when more CTMA is added. However, excessive amounts of CTMA also result in a very rough film surface that causes shorting problems when used in a capacitive structure. A varactor employing a 1-μm-thick DNA biopolymer film as the dielectric is demonstrated. Under 5 V DC bias, which generates E _DC = 5 V/μm, its capacitance at 15 GHz changes by 0.04 pF. This change corresponds to a relative dielectric tunability of 6.6%. A simple application of this varactor for modulation of the power transmitted through a microwave transmission line is also demonstrated.     

Expression of α-amylase inhibitors in diploid Triticum species

The aim of the work was to characterize the expression of various α-amylase inhibitors (αAIs), well known anti-nutritional compounds, for the development of healthier diploid wheat-based functional foods.     

Improved xylitol production in media containing phenolic aldehydes: application of response surface methodology for optimization and modeling of bioprocess

BACKGROUND: The combined effects of vanillin and syringaldehyde on xylitol production by Candida guilliermondii using response surface methodology (RSM) have been studied. A 2² full‐factorial central composite design was employed for experimental design and analysis of the results. RESULTS: Maximum xylitol productivities (Q_P = 0.74 g L^?1h^?1) and yields (Y_P/S = 0.81 g g^?1) can be attained by adding only vanillin at 2.0 g L^?1 to the fermentation medium. These data were closely correlated with the experimental results obtained (0.69 ± 0.04 g L^?1 h^?1 and 0.77 ± 0.01 g g^?1) indicating a good agreement with the predicted value. C. guilliermondii was able to convert vanillin completely after 24 h of fermentation with 94% yield of vanillyl alcohol. CONCLUSIONS: The bioconversion of xylose into xylitol by C. guilliermondii is strongly dependent on the combination of aldehydes and phenolics in the fermentation medium. Vanillin is a source of phenolic compound able to improve xylitol production by yeast. The conversion of vanillin to alcohol vanilyl reveals the potential of this yeast for medium detoxification. Copyright © 2009 Society of Chemical Industry     

Assessment Methods of Fire Damages in Concrete Tunnel Linings

The assessment of fire damage in concrete structures is a complex but intriguing task involving different areas of expertise, from Material Science to Structural Design, from Non-Destructive Testing to Fire Engineering. The problem grows to be even more challenging in the case of tunnels, as a consequence of the high fire severity and the operational difficulties implied by this type of infrastructure, but also because of the pressing time restrictions due to the high cost of traffic disruption during the assessment and repair works. A general overview on this subject is given in the paper, pointing out the different scales of observation, the relevant clues to be analysed at each scale and their appropriate inspection tools. These latter comprise a wide range of investigation techniques of different reliability and cost, but not many of them turn out to be viable and convenient to tackle the problem in question. In this perspective, some innovative assessment methods have been developed in recent years, having in common the ability to reveal the layered structure of fire damaged concrete, the relatively fast and easy implementation and the immediate availability of the results. A brief account on the features and the limitations of these methods is given also, as a tentative to trace some directions for future advances in this important and still open issue.