Nonlinear control synthesis by convex optimization

A stability criterion for nonlinear systems, recently derived by the third author, can be viewed as a dual to Lyapunov's second theorem. The criterion is stated in terms of a function which can be interpreted as the stationary density of a substance that is generated all over the state-space and flows along the system trajectories toward the equilibrium. The new criterion has a remarkable convexity property, which in this note is used for controller synthesis via convex optimization. Recent numerical methods for verification of positivity of multivariate polynomials based on sum of squares decompositions are used.     

SOS-based solution approach to polynomial LPV system analysis and synthesis problems

Based on sum-of-squares (SOS) decomposition, we propose a new solution approach for polynomial linear parameter-varying (LPV) system analysis and control synthesis problems. Instead of solving matrix variables over positive cone, the SOS approach tries to find a suitable decomposition to verify the positiveness of given polynomials. The complexity of the SOS-based numerical method is polynomial of the problem size, and is computationally attractive. This approach also leads to more accurate solutions to LPV systems than most existing relaxation methods. Several examples have been used to demonstrate benefits of the SOS-based solution approach.     

Advanced Methods and Algorithms for Biological Networks Analysis

Modeling and analysis of complex biological networks presents a number of mathematical challenges. For the models to be useful from a biological standpoint, they must be systematically compared with data. Robustness is a key to biological understanding and proper feedback to guide experiments,including both the deterministic stability and performance properties of models in the presence of parametric uncertainties and their stochastic behavior in the presence of noise. In this paper, we present mathematical and algorithmic tools to address such questions for models that may be nonlinear, hybrid,and stochastic. These tools are rooted in solid mathematical theories, primarily from robust control and dynamical systems, but with important recent developments. They also have the potential for great practical relevance, which we explore through a series of biologically motivated examples.     

An efficient hybrid framework for visual tracking using Exponential Quantum Particle Filter and Mean Shift optimization

Multimedia Tools and Applications - Visual object tracking is a key component in many computer vision applications. In real time visual tracking, abrupt changes in speed and direction of the object...     

Tensile rupture of short fibre filled thermoplastic elastomer

Tensile rupture in short silk fibre filled thermoplastic elastomer blends from low-density polyethylene and natural rubber (NR) containing pre-cuts of different lengths has been studied. _b, the tensile strength of the blends, was found to decrease with increase in the cut length in accordance with the Griffith's theory of fracture. However, unlike in the case of vulcanized NR, no critical cut length (at which the strength drops abruptly) was found in the case of both blends and unvulcanized NR. The energy to fracture per unit volume,W _b, also varied inversely with the length of the pre-cut. Values of inherent flaw size,I _O, of the composites, determined by extrapolation ofW _b to the value obtained when no initial pre-cut was present, were found to increase with fibre loading. Blends with longitudinally oriented fibres showed higherI _O values than those with transversely oriented fibres.     

Peptides from the Intestinal Tract of Breast Milk-Fed Infants Have Antimicrobial and Bifidogenic Activity

For bioactive milk peptides to be relevant to infant health, they must be released by gastrointestinal proteolysis and resist further proteolysis until they reach their site of activity. The intestinal tract is the likeliest site for most bioactivities, but it is currently unknown whether bioactive milk peptides are present therein. The purpose of the present study was to identify antimicrobial and bifidogenic peptides in the infant intestinal tract. Milk peptides were extracted from infant intestinal samples, and the activities of the bulk peptide extracts were determined by measuring growth of Escherichia coli, Staphylococcus aureus, and Bifidobacterium longum spp. infantis after incubation with serial dilutions. The peptide profiles of active and inactive samples were determined by peptidomics analysis and compared to identify candidate peptides for bioactivity testing. We extracted peptides from 29 intestinal samples collected from 16 infants. Five samples had antimicrobial activity against S. aureus and six samples had bifidogenic activity for B. infantis. We narrowed down a list of 6645 milk peptides to 11 candidate peptides for synthesis, of which 6 fully inhibited E. coli and S. aureus growth at concentrations of 2500 and 3000 µg/mL. This study provides evidence for the potential bioactivity of milk peptides in the infant intestinal tract.     

Adhesive tack and green strength of EPDM rubber

Measurement of tack of EPDM (ethylene-propylenediene terpolymer) rubber with natural rubber (NR) of four different molecular weights, styrene-butadiene rubber (SBR), butadiene rubber (BR), bromobutyl rubber (BIIR), and polychloroprene rubber (CR) was done over a range of rates of testing, contact times, and temperatures of contact. The effect of different additives, namely carbon black, phenol-formaldehyde resin, coumarone-indene resin, and methyl methacrylate is also reported. Green strength of all the rubbers was measured. Tack strength increases with increase in contact time for all the rubbers. Adhesive tack between EPDM and low-molecular-weight NR is much higher than that between EPDM and NR of high molecular weight. Tack strength of EPDM with BIIR is the highest among the tack values obtained for synthetic rubbers. The adhesive tack between EPDM and natural/ synthetic rubber passes through a maximum when plotted against temperature of contact. It increases with testing rate. All these phenomena could be explained in terms of interdiffusion of rubber chains under different conditions and solubility parameter of two contacting rubbers. It was observed that tack strength varies with (contact time)^1/2 and (rate)^1/2 in accordance with the reptation theory. Phenol-formaldehyde resin (PF) or coumarone-indene (CI) resin in EPDM improves the tack strength quite significantly. The resin in the NR phase does not have a marked effect. The presence of carbon black decreases adhesive tack strength between EPDM and NR. The surface of EPDM, however, becomes smoother with the addition of the additives. Peel tests and commercial tack tests give similar results in the tack strength between EPDM/NR and EPDM/SBR.     

Risk model development for information security in organization environment based on business perspectives

International Journal of Information Security - Digital information plays an essential role in supporting organizational business. However, incidents of sensitive information leakage often happen...