Physical characterization of thermally induced networks of lupin protein isolates prepared by isoelectric precipitation and dialysis

Summary Protein isolates of Lupinus albus were obtained from full fat and defatted lupin flour using isoelectric precipitation or dialysis. Calorimetric tests demonstrated that the main protein fractions of the isolates denature well below 100 °C. Mechanical spectra of isolate dispersions obtained at 80 °C indicated the formation of a 'pseudogel' whose cohesion increased during cooling to 10 °C. Subsequent heating to 90 °C encouraged extensive formation of disulphide bonds as it produced gels that were insoluble in sodium dodecyl sulphate and urea solutions. Dialysis produced isolates of lower gelling concentrations, which also formed networks of a stronger relative elastic character. The presence of NaCl at concentrations up to 0.5 m had a reinforcing effect on networks. Protein over-aggregation caused the opposite effect at higher salt levels. Finally, a comparison with results in the literature on soybean protein gelation suggested similar denaturation temperatures and a common pattern of structure formation for the two legume proteins.     

Spatiotemporal salient points for visual recognition of human actions.

This paper addresses the problem of human-action recognition by introducing a sparse representation of image sequences as a collection of spatiotemporal events that are localized at points that are salient both in space and time. The spatiotemporal salient points are detected by measuring the variations in the information content of pixel neighborhoods not only in space but also in time. An appropriate distance metric between two collections of spatiotemporal salient points is introduced, which is based on the chamfer distance and an iterative linear time-warping technique that deals with time expansion or time-compression issues. A classification scheme that is based on relevance vector machines and on the proposed distance measure is proposed. Results on real image sequences from a small database depicting people performing 19 aerobic exercises are presented.     

A study of forward error correction for mobile multicast

3rd Generation Partnership Project (3GPP) has standardized the use of forward error correction (FEC) for the provision of reliable data transmission in the mobile multicast framework. This error control method inevitably adds a constant overhead in the transmitted data. However, it is so simple as to meet a prime objective for mobile multicast services; that is scalability to applications with thousands of receivers. In this paper, we present a study on the impact of application layer FEC on mobile multicast transmissions. We examine whether it is beneficial or not, how the optimal code dimension varies based on network conditions, which parameters affect the optimal code selection, and how this can be done. Additionally, we focus on one of the most critical aspects in mobile multicast transmission, which is power control. The evaluation is performed with the aid of a novel scheme that incorporates the properties of an evolved mobile network, as they are specified by the 3GPP. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of the Nonsingular Stress Terms on Small-Scale Supercritical Transformation Toughness

In the present paper we examine the influence of the secondorder term of the asympotic stress solution for mode-I, steady-state, plane-strain, quasi-static crack growth in a supercritically trasforming material. It was found that the second-order term can affect the toughness, not always in a positive way. The second-order term includes the effects of the loading, of the overall geometry, and of the crack length. The findings can be used for the evaluation of the purely material resistance curves of small-scale transforming ceramics, as well as for the toughness predictions of these materials. The results may be useful for unifying different test results, and for a better understanding of the strength-toughness relation.     

Numerical modelling and experimental verification of GPR to investigate ring separation in brick masonry arch bridges

The application of ground-penetrating radar (GPR) as a non-destructive technique for the monitoring of ring separation in masonry arch bridges was studied. Numerical modelling techniques were used to simulate tests using GPR—these numerical experiments were backed up and calibrated using laboratory experiments. Due to the heterogeneity of these structures, the signals coming from the interaction between the GPR system and the bridge are often complex, and hence hard to interpret. This defined the need to create a GPR numerical model that will allow the study of the attributes of reflected signals from various targets within the structure of the bridge. The GPR numerical analysis was undertaken using the finite-difference time-domain (FDTD) method. Since “micro regions” in the structure need to be modelled, subgrids were introduced into the standard FDTD method, in order to economize on the required memory and the calculation time. Good correlations were obtained between the numerical experiments and actual GPR experiments. It was shown both numerically and experimentally that significant mortar loss between the masonry arch rings can be detected. However, hairline delaminations between the mortar and the brick masonry cannot be detected using GPR.     

A Novel End-to-End Architecture for H.264 Video Streaming over the Internet

In this paper we propose a novel end-to-end architecture for H.264 unicast video streaming over the Internet. The proposed video streaming architecture is based primarily on a new transport layer protocol, the stream control transmission protocol (SCTP). We show that the network-friendly specification of H.264, and the novel technical characteristics of SCTP, when coupled together are able to provide a highly adaptive and flexible system for unicast video streaming. More specifically, we develop algorithms that handle at the transport layer the following functions concerning video packet transmission: retransmission policy, packet prioritization, implicit receiver feedback. We combine the above algorithms with an R-D optimization strategy at the encoder, that provides more options when adapting to bandwidth variations. This combined optimization strategy leads to more options concerning the streaming parameters. Finally, with simulation results we prove that our system is capable of maintaining good perceptual quality and TCP-friendliness under various loss conditions. An early version of this paper appeared in CCNC 2004.     

Nafion-clay hybrids with a network structure

Nafion-clay hybrid membranes with a unique microstructure were synthesized using a fundamentally new approach. The new approach is based on depletion aggregation of suspended particles - a well-known phenomenon in colloids. For certain concentrations of clay and polymer, addition of Nafion solution to clay suspensions in water leads to a gel. Using Cryo-TEM we show that the clay particles in the hybrid gels form a network structure with an average cell size in the order of 500 nm. The hybrid gels are subsequently cast to produce hybrid Nafion-clay membranes. Compared to pure Nafion the swelling of the hybrid membranes in water and methanol is dramatically reduced while their selectivity (ratio of conductivity over permeability) increases. The small decrease of ionic conductivity for the hybrid membranes is more than compensated by the large decrease in methanol permeability. Lastly the hybrid membranes are much stiffer and can withstand higher temperatures compared to pure Nafion. Both of these characteristics are highly desirable for use in fuel cell applications, since a) they will allow the use of a thinner membrane circumventing problems associated with the membrane resistance and b) enable high temperature applications.