New closed-form expressions for SNR estimates of Nakagami fading channels by the method of moments

Method of moments has been a parameter estimation technique appropriate to calculate signal-to-noise ratio (SNR) estimates in fading channel models in which an optimal technique like maximum likelihood estimation is not mathematically tractable. In this article, the ratio of the second moment squared to the fourth moment of the received signal envelope is considered to calculate an exact expression for the SNR estimate in Nakagami-m fading channel for M-QAM and \(\theta \)-MQAM modulations as well as expressions to evaluate the variance and the mean of the estimate. The paper presents two useful contributions for SNR estimation theory on Nakagami fading. Besides the exact algebraic expression for the estimate for a generalized QAM modulation scheme, its performance is evaluated through a statistical linearization argument.     

Chemical characterization of selected Western Canadian Spring and durum wheat cultivars using the Cornell net carbohydrate and protein analysis

This study determined the chemical composition of new Canada Prairie Spring (CPS, n = 5) and durum (n = 5) wheat cultivars, relative to a common Canada Western Red Spring (Katepwa) and durum (Kyle) wheat, which were used to predict the total digestible nutrient of these cultivars in cattle. The results showed that test weight differed among the spring wheat cultivars (74.9 to 79.9 kg hlitre⁻¹) and was similar among the durum cultivars (average 79.7 kg hlitre⁻¹). Relative to Katepwa, Genesis had higher (P < 0.05) neutral detergent fibre and starch and lower (P < 0.05) crude protein levels. Differences among the other CPS cultivars were small. Chemical composition was uniform among the durum cultivars except for neutral detergent fibre which was higher (P < 0.05) in Sceptre and AC Morse than Kyle. Carbohydrate fractionation showed that intermediately degradable carbohydrate is the main component of dry matter in CPS (664.7 g kg⁻¹) and durum (656.0 g kg⁻¹) wheat. In both types of wheat, true protein was the main protein fraction followed by non-protein nitrogen and unavailable protein, respectively. Total digestible nutrient was similar among the CPS and the durum cultivars. It was concluded that while some differences in chemical composition were observed between CPS cultivars, there was little or no variation among durum cultivars. © 1999 Society of Chemical Industry     

Anodic porous alumina structural characteristics study based on SEM image processing and analysis

The present work reports the porous alumina structures fabrication and their quantitative structural characteristics study based on mathematical morphology analysis by using the SEM images. The algorithm used in this work was implemented in 6.2 MATLAB software. Using the algorithm it was possible to obtain the distribution of maximum, minimum and average radius of the pores in porous alumina structures. Additionally, with the calculus of the area occupied by the pores, it was possible to obtain the porosity of the structures. The quantitative results could be obtained and related to the process fabrication characteristics, showing to be reliable and promising to be used to control the pores formation process. Then, this technique could provide a more accurate determination of pore sizes and pores distribution.     

Design Criteria for Horseshoe and Spiral-Based Interconnects for Highly Stretchable Electronic Devices

Stretchable electronics can be used for numerous advanced applications such as soft and wearable actuators, sensors, bio-implantable devices, and surgical tools because of their ability to conform to curvilinear surfaces, including human skin. The efficacy of these devices depends on the development of stretchable geometries such as interconnection-based configurations and the associated mechanics that helps to achieve optimum configurations. This work presents the essential mechanics of silicon (Si) island-interconnection structures, which include horseshoe and spiral interconnections, without reducing the areal efficiency. In particular, this study demonstrates the range of the geometrical parameters where they have a high stretchability and cyclic life. The numerical results predict the areas that are prone to breaking followed by experimental validation. The figure-of-merit for these configurations is achieved by mapping the fracture-free zones for in-plane and out-of-plane stretching with essential implications in stretchable and wearable system design. Furthermore, this work demonstrates the mechanical response for a range of materials (i.e., copper, gold, aluminum, silver, and graphene) that experience the plastic deformations in contrast to conventionally used Si-based devices that represent the extended usage for advanced stretchable electronic devices. The detailed mechanics of these configurations provides comprehensive guidelines to manufacture wearable and stretchable electronic devices.     

Neural models for an asymmetric coplanar stripline with an infinitely wide strip

This paper presents a new approach, based on artificial neural networks (ANNs), to determine the characteristic impedance and the effective permittivity of an asymmetric coplanar stripline (ACPS) with an infinitely wide strip. ANNs are trained with five learning algorithms to obtain better performance and faster convergence with simpler structure. The best results for training and test were obtained from the models trained with the Levenberg–Marquardt and the Bayesian regularization algorithms. The results obtained by using the neural model are in very good agreement with the results available in the literature. The neural models presented in this work provide simplicity and accuracy to determine both the parameters of an ACPS. The method is not time consuming and is easily included in a CAD system.     

The circuit realization of Mexican Hat wavelet function

A wavelet network circuit implementation for Mexican Hat mother wavelet has been proposed for nonlinear function approximation which can also be used for the realization of the algebraic nonlinear components. The Mexican Hat mother wavelet function has been implemented with discrete circuit components and it has been observed that the experimental waveform obtained from the realized circuit is approximately same as the Spice simulation of the original function. The circuit simulations of exemplar functions implemented in Spice are also given.     

Real traffic logs creation for testing intrusion detection systems

Port scanning is one of the most popular reconnaissance techniques that many attackers use to profile running services on a potential target before launching an attack. Many port scanning detection mechanisms have been suggested in literature. To test the proposed detection approaches, researchers use data sets that are available online or simulate their own. However, the available data sets do not provide complete logs and are usually outdated. Furthermore, the simulated data sets provide logs that do not resemble real‒life scenarios. These deficiencies in the available data sets highly affect the performance of testing the intrusion detection systems (IDSs) and result in poor evaluations. Meanwhile, very little work has been done on generating port scanning benchmarks that researchers can use to test their detection methods. In this work, we suggest a simulation framework using OMNeT++ to generate benchmarks that resemble real‒life traffic. We approach the problem by dividing it into three modules: (1) topology creation; (2) good traffic generation; and (3) bad traffic generation, each of which are made realistic, similar to deployed and usable networks. The benchmark is then tested using Snort and MalwareAnalysis. The tested IDSs were not able to catch many of the generated port scanning attacks, specifically the slow and distributed ones. We also measured the attack detection efficiency of the IDSs under different loads of background activities. Hence, the proposed framework and the annotated benchmarks will provide researchers and industry with an effective way of testing the power of IDSs' port scanning detection modules. Copyright © 2014 John Wiley & Sons, Ltd.     

Improved Analysis for Distortion in Emitter-Driven Variable Gain Pairs

This article presents an improved analysis for the distortion inemitter-driven variable-gain pairs owing to the Early-voltage effect. Theanalysis shows that, by careful design, it is possible to reduce thesecond-order distortion components resulting from the Early-voltage effect.The analysis shows also that, under large signal conditions, the value ofthe normalized input amplitude at which the second-harmonic distortion isminimum is different from the value of the normalized input amplitude atwhich the second-order intermodulation distortion is minimum.     

Static crack extension prediction in aluminium alloy at low temperature

The evaluation of the crack initiation and crack extension under different environmental conditions is very important for many engineering applications. Several crack extension criteria have been proposed in the last decades, but each criterion can be employed only for particular materials, loading configurations, environmental conditions. In the present paper, the R-criterion (minimum extension of the core plastic zone) is modified in order to take into account the temperature dependence. The modified criterion is herein employed to predict the crack path and the crack extension force for an edge-cracked finite plate under tension, by using a simplified procedure to determine the stress-intensity factor (SIF) for different initial crack configurations. Then, results concerning some experimental tests performed on edge-cracked aluminium alloy sheet specimens at different temperatures are reported. Finally, the theoretical results are compared (in terms of crack extension force and crack path) with the experimental data.     

The microwave-assisted synthesis and structural characterization of novel,dithia-bridged polymeric phthalocyanines containing a substituted thiophenylamine Schiff base

Novel polymeric metal-free and metallo(Cu(II), Co(II), Ni(II), Zn(II) and Pb(II))–phthalocyanine complexes were synthesized using microwave irradiation and the products were purified by several (crystallization and preparative thin layer) techniques. The newly prepared compounds were characterized by a combination of elemental analyses, IR, ¹H/¹³C NMR, ¹H–¹H COSY, MS and UV–Vis spectroscopy. In order to better understand the spectroscopy data (especially for ¹H/¹³C NMR and ¹H–¹H COSY techniques), computational calculations were used for characterization at DFT/6-31G(d) level. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core.