Intrusion Detection System for Wireless Sensor Networks Using Danger Theory Immune-Inspired Techniques

An IDS framework inspired in the Human Immune System to be applied in the wireless sensor network context is proposed. It uses an improved decentralized and customized version of the Dendritic Cell Algorithm, which allows nodes to monitor their neighborhood and collaborate to identify an intruder. The work was implemented and tested both in simulation and in real sensor platform scenarios, comparing them to each other and was also compared to a Negative Selection Theory implementation in order to demonstrate its efficiency in detecting a denial-of-sleep attack and in energy consumption. Results demonstrated the success of the proposal.     

Hybrid modeling techniques for multilayered printed circuit board in power electronics: association of electromagnetic methods

With the fast development of power electronics circuits at increasing switching frequency (over 10 MHz), the multilayered printed circuits boards (PCBs) are being used more and more in the field of power electronics. In this paper, two main computational methods are presented to simulate the dynamic behavior of power electronics interconnection systems. Our aim is to present a methodology to analyze the electromagnetic (EM) behavior of power PCB regarding parasitic effects ( EM couplings) or dynamic effects (impedance): a general procedure is given to calculate EM couplings between strip conductors in multilayered configurations based on the principle of hybrid methods. Finally, we propose a new method to limit computation time based on matrix sparsification.     

Generalized Nakagami-m phase crossing rate

This paper provides simple, exact, new closed-form expressions for the generalized phase crossing rate of Nakagami-m fading channels. Sample numerical results obtained by simulation are presented that validate the formulations developed here. A special case of this formulation is the Rayleigh case, whose result agrees with that obtained elsewhere in the literature. In passing, several new closed-form results concerning the statistics of the envelope, its in-phase and quadrature components, phase, and their time derivatives are obtained.     

An Evolutionary Method for Synthesizing Low-Sensitivity Lossless Matching Networks

Whereas the present practice of designing matching networks for antennas is limited to conventional topologies, requiring a significant amount of domain knowledge, evolutionary algorithms can be used for automatically identifying unconventional designs that are more effective than would otherwise be developed. In this work, an automatic method to design lossless matching networks driven by an evolutionary algorithm (EA) that considers the sensitivities of the network parameters during the synthesis process is presented. To this end, a closed-form expression for the transducer power gain (TPG) sensitivity with respect to the component values is employed in such a way that the effects of the components tolerance on the matching network performance can easily be quantified. A 3D data structure based on the adjacency matrix is conveniently used to represent any type of network topologies. The proposed EA employs a novel set of topology variation operators, tailored for changing the circuit topology, and an association step, with the aim of reducing the number of nodes of the matching circuit. The efficiency of the proposed EA is tested in the synthesis of an impedance matching network for a VHF monopole whip antenna. This study’s results indicate a matching bandwidth improvement, a more uniformly distributed TPG along the operation frequency band and a more stable TPG regarding the components tolerance compared to the results obtained by previous approaches.     

A wavelet‐based expert system for digital subscriber line topology identification

This work proposes a new method for automatically identifying topologies of lines with one or more sections in a telephone network. The method is based on the examination of both impulse response and time‐domain reflectometry trace of a line under test. They are analyzed using a method based on the wavelet transform that identifies and extracts features that contain information about the line topology. Those features are interpreted by an expert system composed of three sequential modules that estimate, respectively, the type of line makeup (serial or bridge tap), the lengths of the line sections, and the corresponding cable type, which are the parameters that completely identify the topology according to the assumed model. A thorough comparison with two state‐of‐the‐art methods is also presented using several twisted‐pair copper cables. The results show that the proposed method provides good accuracy with respect to topology identification at low computational cost. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and characterization of Pt‐CMK‐3 hybrid nanocomposite for hydrogen storage

The nanometric carbon CMK‐3 modified with Pt was synthesized and applied as a reservoir for hydrogen uptake. We found that the newly synthesized hybrid composites exhibited significantly enhanced H₂ storage. The approach that we have followed includes synthesis of nanostructures with the experimental study of its adsorption capacity and storage properties. In summary, we have shown that CMK‐3 ordered porous carbon modified with Pt nanoclusters is a promising material for hydrogen uptake. The samples were characterized by X‐ray diffraction, N₂ isotherms, X‐ray photoelectron spectra and transmission electron microscopy. The nanoparticles of Pt (~1.7 nm) incorporated onto the nanostructured carbon CMK‐3 showed higher hydrogen uptake at low and high pressures (3.3 wt% of H₂ sorption at 10 bar and 77 K) than CMK‐3. Copyright © 2014 John Wiley & Sons, Ltd.     

Nutritional and sensory evaluation of macaroni supplemented with fish protein concentrate

The present work consisted of the supplementation of macaroni with fish protein concentrate (FPC) at the levels of 5, 10, 15, and 20% in relation to wheat flour. The FPC was obtained from eviscerated and deboned trairas (Hoplias malabaricus), using boiling ethanol as a solvent at a pH range of 5.5 to 6.0. The FPC showed desirable aspects such as bright color, no off-flavor, high levels of protein (84.3 g/100 g) and lysine (484 mg/g N) and low levels of fat (0.4 mg/100 g) and moisture (8.6 g/100 g). The macaroni became slightly dark in color with increasing additions of FPC. Nevertheless, the 20% level was the only one not accepted by the testing panel, in terms of color and flavor. Weanling Wistar rats were used in the biological assay to measure the macaroni protein quality at the different supplementation levels. Analyses of PER, NPR, NPU, digestibility and retained carcass N were carried out. The protein quality of the macaroni was improved by the addition of FPC. The level of 10% was similar to the casein and no subsequent improvement in the protein quality was notified with higher levels of FPC. Due to its high lysine content, the FPC is a promising supplement for cereals. From the nutritional and sensory aspects, the 10% level of FPC was the most satisfactory for macaroni supplementation.     

Interpolating datasets with trends: A modified median polish approach

This article investigates an alternative method to deal with data sets in the presence of trends. Median polish kriging (MPK) was introduced as an alternative solution to universal kriging or intrinsic random functions of order k (IRF-k) for estimation in the presence of trends. The maps obtained using the original MPK algorithm show banding artefacts which do not appear in the reference data set. A modified version of MPK was introduced to attempt to remove the banding artefacts. The results confirm the improvement in quality of estimate using the modified version of MPK (called MPKm), which takes into account the problems of clustered samples and boundary effect associated with the re-addition of the trend along bands. The variation introduced in the median polish algorithm proved to be satisfactory in eliminating the artefacts.     

Hydroxyapatite deposition study through polymeric process on commercially pure Ti surfaces modified by laser beam irradiation

Many techniques have been used to coat metallic substrate with bioceramics. The aim of this study was to study the physical-chemical characteristics of polyvinylidene fluoride (α-PVDF)/hydroxyapatite (HA) composite coating, obtained by casting method, on commercially pure titanium (α-CP Ti) substrate surface modified by laser beam irradiation. The preparation of coating was done for mixing α-PVDF pellets shape dissolved in dimethylacetamide (DMA) with HA/DMA emulsion. The mixture was poured onto the α-CP Ti sample and left to dry in an oven. CP Ti plates were coated with α-PVDF/HA composite film, in proportions of 100/00 and 60/40 in weight, and characterized by particle size analysis, scanning electron microscopy, energy dispersive spectroscopy (EDS), X-ray diffractometry, thickness measurement and contact angle. Uniform coating with a small thickness variation along the coated surface was successfully obtained.     

Influence of Particle Size on Nonisothermal Crystallization in a Lithium Disilicate Glass

In this study, lithium disilicate (LS₂) glass samples with different particle sizes ranging from less than 105 to 850 μm were prepared. These specimens were inserted in a Pt‐Rh DSC crucible and heated to 850°C at different rates (? = 0.5–30 K/min) to identify their crystallization peaks. The activation energies for the overall crystallization (E) and the Avrami coefficient (n) were evaluated using different nonisothermal models. Specifically, n was evaluated using the Augis–Benett model and the Ozawa method, and E was evaluated using the Kissinger and Ligero methods. As expected, the coarse particles mainly crystallized in the volume, while surface crystallization was predominant in the samples with particle sizes of less than 350 μm. This result was confirmed through SEM analysis of the double stage heat‐treated samples. In contrast with previous studies, our results demonstrated that the activation energy decreased as the particle size increased. In addition, no clear correlation between the peak intensity (δT_p) and the particle size was observed.