Elongational viscosity of LDPEs and polystyrenes using entrance loss data

For two low‐density polyethylenes and two polystyrenes, axisymmetric and planar elongational viscosities are estimated using entrance loss data from capillary and slit rheometers, respectively. The elongational viscosity is estimated by optimizing the values of various parameters in the Sarkar–Gupta elongational viscosity model such that the entrance loss predicted by a finite element simulation agrees with the corresponding experimental data. The predicted entrance loss is in good agreement with the experimental data at high flow rates. The difference in the experimental and predicted entrance loss at lower flow rates might have been caused by large error in the experimental data in this range. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers     

The schnittaxiom and unions of fuzzy subgroups

A necessary and sufficient condition for the union of an arbitrary family of fuzzy subgroups of a group to be a fuzzy group has been proposed. The criterion which gives a cut of the unit interval is called the Schnittaxiom. It has been applied successfully to investigate fuzzy subgroupness of arbitrary unions of homomorphic images and preimages.     

Wavelet domain-based video noise reduction using temporal discrete cosine transform and hierarchically adapted thresholding

A novel spatio-temporal filter for video denoising, which operates entirely in the wavelet domain, is proposed. For effective noise reduction, the spatial and temporal redundancies that exist in the wavelet domain representation of a video signal are exploited. First, a 2D discrete wavelet transform is applied to the input noisy frames. This is followed by a discrete cosine transform (DCT), which is applied to the temporal subband coefficients to minimise the redundancy among the consecutive frames. The DCT transformed, noise-free coefficients in the different wavelet domain subbands for the original image sequence are modelled using a prior having a generalised Gaussian distribution. On the basis of this prior, filtering of the noisy wavelet coefficients in each subband is carried out using a new, low-complexity wavelet shrinkage method, which utilises the correlation that exists between subsequent resolution levels. Experimental results show that the proposed scheme outperforms several state-of-the-art spatio-temporal filters in terms of both the peak signal-to-noise ratio and the visual quality     

Studies on the electrical conductivity and galvanomagnetic characteristics of short carbon fibre filled thermoplastic elastomers

The electrical resistivity of short carbon fibre filled thermoplastic elastomers based on natural rubber-high density polyethylene (NR-HDPE) blend and styrene-isoprene-styrene (S-I-S) block copolymer has been studied by varying the concentration of fibre from the 0 to 40 phr level. A sharp drop in resistivity is observed in both cases after a critical concentration of fibre is reached, with the S-I-S system showing lower values of critical concentration. At higher concentrations, experimental values of the electrical conductivity agreed reasonably well with the calculated values from a theory based on the probability of formation of a conductive network. The effect of temperature on the resistivity of the composites has also been investigated in a temperature range of 27–120 °C and 27–90 °C for the NR-HDPE system and S-I-S system, respectively. The type of carrier in both the composites is found to be n-type, i.e. electrons, and the activation energy of hopping of the electrons for both the systems has been calculated. A Hall effect study has also been carried out to determine the carrier concentration and drift mobility of both the composites.     

Traffic classification and scheduling in ATM networks

Virtual paths (VPs) are an integral part of the resource management and control hierarchy of ATM (asynchronous transfer mode) networks. To improve the utilization of network resources and facilitate management and control, source types are organized into traffic classes. Each traffic class is transported by its own virtual path subnetwork. In this paper, we consider issues related to the design of traffic classes. We consider an ATM switch node to which cells arrive from a diverse set of source types. Traffic classes are assumed to be served according to a weighted round robin policy, while cells belonging to a given traffic class are served in first-come-first-served order. We consider the problem of determining the optimal set of traffic classes. Under suitable simplifying assumptions, it is shown that the above problem can be modeled as a set-partitioning problem. The structure of the problem at hand is then exploited to develop an efficient heuristic. Several examples are given to illustrate the developed methodology.Supported partially through NSF Grant NCR-891447 and AT&T Grant 5-23690.     

Binary rewriting and call interception for efficient runtime protection against buffer overflows

Buffer overflow vulnerabilities are one of the most commonly and widely exploited security vulnerabilities in programs. Most existing solutions for avoiding buffer overflows are either inadequate, inefficient or incompatible with existing code. In this paper, we present a novel approach for transparent and efficient runtime protection against buffer overflows. The approach is implemented by two tools: Type Information Extractor and Depositor (TIED) and LibsafePlus. TIED is first used on a binary executable or shared library file to extract type information from the debugging information inserted in the file by the compiler and reinsert it in the file as a data structure available at runtime. LibsafePlus is a shared library that is preloaded when the program is run. LibsafePlus intercepts unsafe C library calls such as strcpy and uses the type information made available by TIED at runtime to determine whether it would be ‘safe’ to carry out the operation. With our simple design we are able to protect most applications with a performance overhead of less than 10%. Copyright © 2006 John Wiley & Sons, Ltd.     

Fatigue characteristics of pulsed MIG-welded Al-Zn-Mg alloy

Pulse-current MIG welding of Al-Zn-Mg alloy was carried out using an extruded section of base material and Al-Mg (5183) filler wire. During welding the pulse parameters such as the mean current and pulse frequency were varied and their effect on the geometry and porosity content of weld deposit as well as the fatigue life of the weldment was studied. The pulse parameters were found to affect significantly the geometry and porosity content of weld deposit and consequently the fatigue life of the weldment. For a comparative study, weldments were also prepared by using conventional continuous current MIG-welding process, where welding currents equivalent to the mean currents of pulsed process were used. The fatigue life of the weldment was correlated with the geometry and porosity content of weld deposit.     

Pulsed underwater corona discharges as a source of strong oxidants: *OH and H2O2.

Because of undesirable side effects of chemical methods pulsed underwater corona discharges are emerging as a potential future advanced oxidation process (AOP) for water disinfection. In pulsed corona discharges a discharge channel is created, which contains a non-thermal plasma with a low degree of ionisation and low electron densities, but with electron energies of up to 10 eV. It has been demonstrated that electrons with this energy can dissociate water and oxygen molecules and produce various reactive radicals (*OH, H*, O*, HO2*), molecular species (H2O2, H2, O2), ultraviolet radiation and shock waves. It is supposed that the combination of all effects leads to a very efficient killing of microorganisms. To understand this in detail and to improve the efficiency of the overall system there is the need to develop suitable diagnostic methods for the quantitative determination of the various oxidants produced during the discharge. In this paper we present preliminary experimental results obtained with different chemical probes for *OH radicals, and H2O2 produced by pulsed corona discharges.