Performance evaluation of an authentication solution for IMS services access

The IP Multimedia Subsystem (IMS) is an access-independent, IP based, service control architecture. Users’ authentication to the IMS takes place through the AKA (Authentication and Key Agreement) protocol, while Generic Bootstrapping Architecture (GBA) is used to authenticate users before accessing the multimedia services over HTTP. In this paper, we focus on the performance analysis of an IMS Service Authentication solution that we proposed and that employs the Identity Based Cryptography (IBC) to personalize each user access. We carry out the implementation of this solution on top of an emulated IMS architecture and evaluate its performance through different clients’ access scenarios. Performance results indicate that increase in the number of clients does not influence the average processing time and the average consumed resources of the GBA entities during the authentication. We also notice that the Bootstrapping Server Function (BSF) presents a bottleneck during the service authentication which helps in giving some guidelines for the GBA entities deployment.     

Study of the Effect of Natural Rubber-graft-maleic Anhydride (NR-g-MA) on the Compatibility of NR-NBR Blends Using the Ultrasonic Technique

The grafted copolymer of natural rubber (NR) and maleic anhydride (MA) was synthesized in a solution state by using ultraviolet radiation. The NR-g-MA was characterized using infrared (IR) technique. The prepared NR-g-MA was added to a 50/50 blend of NR and acrylonitrile-butadiene copolymer (NBR) as a compatibilizer. The effect of compatibilizer (NR-g-MA) concentrations in the range of 2, 4, 5, 6, 8, and 10 wt.% on the ultrasonic velocity, attenuation coefficient, and ultrasonic viscosity was studied in order to study the compatibility of the 50NR-50NBR blend. Ultrasound pulse echo method was used to measure both the ultrasound velocities and attenuation coefficient at a frequency of 2 MHz. Testing for elastic constant, Poisson's ratio, cross-link density, and microhardness was carried out in different percentages of the blend components to study the degree of the compatibility of the blend. The structure of the blend system was established by differential scanning calorimetry. The addition of NR-g-MA to the blend showed improvement of compatibility in certain concentration ranges and deterioration of compatibility in other ranges.     

Adaptation of the simulated annealing optimization algorithm to achieve improved near-optimum objective function values and computation times for multiple component manufacture

The paper concerns the development of the Simulated Annealing Algorithm (SAA) for the sequencing of cutter tool movement in machine tools capable of manufacturing many components, located on a box-like jig/pallet, in a single setting using a multiple tool magazine. The objective of the SAA is to minimise the total machine tool residence time. The general SAA has been enhanced, to achieve lower values of the objective function during the iterative scheme, and hence improve solution accuracy; and, to reduce computation time by cessation of the iterative scheme when no further improvement in the objective function occurs. The reconfigured SAA has been evaluated using a number of case studies. The results show that a reduction in the objective function value can be achieved in up to 6%, with far less computational effort. In addition, it is shown that the computation time can be reduced by a factor of between 20% and 72%. The improvement in the objective function value and the computational speed depends on the complexity of the problem posed to the SAA software.     

The placement of central venous catheters in infants with cardiac shunts: safety measures and false alarms

We report a case of RVT, diagnosed at 34 weeks' gestation in a case of fetal distress occurring four days after an acute maternal gastroenteritis. The typical ultrasonic pattern included renal enlargement, with parenchymal hyperechogenicity and venous echoic streaks, loss of the cortico-medullary boundary and lack of definition of renal sinus echoes. Color Doppler velocimetry confirmed the absence of venous flow with an increased vascular resistance in the renal artery. After delivery by an emergency caesarean section the infant had a full anatomical and functional recovery of his affected kidney at the seventh day of life.     

Fast cancellation of sidelobes in the pattern of a uniformlyexcited array using external elements

A method for wide null-steering in the pattern of a uniformly excited linear array that utilizes the edge elements of the array is investigated. Simpler and faster algorithms for sidelobe reduction are introduced which use one or two external edge elements. Comparisons between these methods are held. Sample results are given     

Multiple-jet electrospinning methods for nanofiber processing: A review

Electrospinning is a versatile method of producing continuous nanofibers through the application of an electric field. The simplest and earliest form of electrospinning involves the use of a single-needle spinneret to draw the solution out and form fibers. The process, however, is very time consuming, limiting the potential wide-scale application of electrospun nanofibers. Many multiple-jet electrospinning methods have been proposed to overcome the problem of low productivity, but the generation of multiple jets brought about other problems such as jet repulsion, lower process controllability, and deterioration of fiber quality. Thus, continuous development is necessary for the optimization of the process. The aim of this review is to provide an overview of the recent electrospinning technologies reported in the literature, particularly on various multiple-jet electrospinning methods from both nozzles and free surfaces. The general principle underlying the electrospinning process, as well as important parameters involved are also presented in this paper.     

Detection and spy sensors in discrete distributed systems

The aim of this work is to study the problem of detection of sources in discrete distributed systems. We characterize discrete detectable sources and spy sensors and we give the relationship between these sensors and strategic sensors. Then we show how to reconstruct a detectable source from the corresponding output, in the cases where the observation is exact or affected by an observation error. In the case of sources located in a subregion of the geometrical support of the considered system, we study the problem of regional detection and reconstruction of discrete sources. Examples and numerical results are also given.     

IRDNU-Net: Inception residual dense nested u-net for brain tumor segmentation

Accurate segmentation of brain tumors is an essential stage in treatment planning. Fully convolutional neural networks, specifically the encoder-decoder architectures such as U-net, have proven successful in medical image segmentation. However, segmenting brain tumors with complex structure requires building a deeper and wider model which increases the computational complexity and may also cause the gradient vanishing problem. Therefore, in this work, we propose a novel encoder-decoder architecture, called Inception Residual Dense Nested U-Net (IRDNU-Net). In this model carefully designed Residual and Inception modules are used in place of standard U-Net convolutional layers to increase the width of the model without increasing the computational complexity. Additionally, in the proposed architecture, the encoder and decoder are connected via a sequence of Inception-Residual densely nested paths to extract more information and increase the depth of the network while reducing the number of network parameters. The proposed segmentation architecture was evaluated on two large brain tumor segmentation benchmark datasets; the BraTS’2019 and BraTS’2020. It achieved a mean Dice similarity coefficient of 0.888 for the whole tumor region, 0.876 for the core region, and 0.819 for the enhancement region. Experimental results illuminate that IRDNU-Net outperforms U-Net by 1.8%, 11.4%, and 11.7% in the whole tumor, core tumor, and enhancing tumor, respectively. Moreover, the IRDNU-Net enables a great improvement on the accuracy compared to comparative approaches, and its ability in the face of challenging problems, such as small tumor regions, with fewer parameters.

     

Improvement of the acoustic and mechanical properties of sponge ethylene propylene diene rubber/carbon nanotube composites crosslinked by subsequent sulfur and electron beam irradiation

In this research, sponge ethylene propylene diene rubber (EPDM) nanocomposites based on functionalized multi-walled carbon nanotubes (f-MWCNTs) and foaming agent azodicarbonamide (AZD) were successfully fabricated as potential acoustic-absorbing foams. Two crosslinking systems were utilized for stabilizing the foam structure and improving its properties by subsequent sulfur and electron beam irradiation at 50 kGy as a fixed dose. The impacts of the concentration of AZD, f-MWCNTs and crosslinking systems on acoustic and physico-mechanical properties were investigated. The results manifested that the optimum foaming content was 3 phr. The acoustic data exhibited satisfactory enhancement in the sound absorption coefficient (α) for irradiated foam nanocomposites compared to unirradiated nanocomposites. This was attributed to the barrier effect of f-MWCNTs in reducing the pore size of the foam, leading to an increase in the tortuous path in the foam matrix that stifled the sound waves from transferring into the bulk. Likewise, the compression properties were also improved. However, tensile stress and strain at break values for irradiated foams relatively decreased. The data obtained revealed an excellent possibility of using these EPDM foam nanocomposites for potential applications such as acoustic panels and airborne sound insulation. © 2022 Society of Industrial Chemistry.