Coalitional game‐based behavior analysis for spectrum access in cognitive radios

The core of cognitive radio paradigm is to introduce cognitive devices able to opportunistically access the licensed radio bands. The coexistence of licensed and unlicensed users prescribes an effective spectrum hole‐detection and a non‐interfering sharing of those frequencies. Collaborative resource allocation and spectrum information exchange are required but often costly in terms of energy and delay. In this paper, each secondary user (SU) can achieve spectrum sensing and data transmission through a coalitional game‐based mechanism. SUs are called upon to report their sensing results to the elected coalition head, which properly decides on the channel state and the transmitter in each time slot according to a proposed algorithm. The goal of this paper is to provide a more holistic view on the spectrum and enhance the cognitive system performance through SUs behavior analysis. We formulate the problem as a coalitional game in partition form with non‐transferable utility, and we investigate on the impact of both coalition formation and the combining reports costs. We discuss the Nash Equilibrium solution for our coalitional game and propose a distributed strategic learning algorithm to illustrate a concrete case of coalition formation and the SUs competitive and cooperative behaviors inter‐coalitions and intra‐coalitions. We show through simulations that cognitive network performances, the energy consumption and transmission delay, improve evidently with the proposed scheme. Copyright © 2016 John Wiley & Sons, Ltd.     

Brown tumors in dialyzed patients with secondary hyperparathyroidism: Report of 16 cases

Brown tumors (BTs) are relatively uncommon but they are serious complications of renal osteodystrophy. The objective of this study was to analyze the clinical, biological, and radiological characteristics of 16 patients with BTs provoked by secondary hyperparathyroidism (sHPT) and its response to the decrease in parathyroid hormone levels after parathyroidectomy (PTX). The management of that uncommon condition was also reviewed. We conducted a retrospective study including 16 end‐stage renal disease patients who underwent subtotal PTX between 1997 and 2007 for severe sHPT with BTs. Our study included 10 men and 6 women, whose average age was 34 years. All patients were on dialysis. Ten of them were on dialysis for more than 5 years. The median duration on dialysis was 84 months. Patients included suffered from swellings associated with functional limitations. BTs had multiple locations in 7 patients. Jaw was the most frequent location (62%). Radiography and tomodensitometry demonstrated a mixed radio lucent and radio‐opaque lesions with an expansion of the cortical bone. Bone scan demonstrated an increased uptake of lesions. Chirurgical treatment was indicated in all cases because of severe refractory sHPT with functional limitations and/or disfiguring deformities. In all cases, BTs stopped its progression and even decreased in size. However, it was insufficient in four cases, which required a surgical resection. PTX remains an efficacious approach in resistant cases of sHPT with persistent BTs.     

Impact of surface hardening treatment generated by shot peening on the fatigue life of brass alloy

Brass alloy is widely used because of some attractive properties such as high electrical and thermal conductivity. But its fatigue performance after surface treatment is not very well explored in literature. Thus, in the present work, particular emphasis was given to the influence of surface treatment by shot peening on the fatigue life of brass alloy, throughout surface roughness and microstructural evolution. Fatigue tests were performed on unpeened, peened and peened then polished specimens. Various times of surface hardening treatment as 30, 60 and 120 min were considered. Experimental results reveal that the fatigue life of peened brass alloy decrease for all studied hardening treatment conditions. Surface roughness and microstructural properties showed large sensitivity to the shot peening process of brass alloy.     

Physiological changes, phenolic content and antioxidant activity of Salvia officinalis L. grown under saline conditions

BACKGROUND: Hydroponic culture was used to investigate the effect of NaCl concentrations on the growth, nutrient uptake, phenolic content and antioxidant activity of Salvia officinalis L. leaves. The antioxidant capacity of the methanolic extract of S. officinalis was evaluated by using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging test and β‐carotene‐linoleic acid bleaching assay. Physiological and biochemical parameters of S. officinalis were assessed after 4 weeks of salt treatment with 0, 25, 50, 75 and 100 mmol L^?1 NaCl. RESULTS: Plant growth exhibited a reduction of 61% at 100 mmol L^?1 NaCl. Assessment of Na⁺, K⁺ and Ca²⁺ and water contents of shoots and roots showed that S. officinalis is able to regulate Na⁺ concentration by active compartmentation in vacuoles. Salvia officinalis phenolics were increased in response to salinity at the threshold of 75 mmol L^?1 NaCl. This herb was also found to be able to achieve important DPPH^? quenching activity and to inhibit the β‐carotene‐linoleic acid bleaching notably enhanced by salt treatment. It is interesting to highlight the correlation between the phenolic and antioxidant activity, suggesting the involvement of these compounds in this activity. CONCLUSION: Salvia officinalis treated with 75 mmol L^?1 NaCl constitutes a potential source for production of secondary metabolites useful in several applications. Copyright © 2011 Society of Chemical Industry     

Conductometric biosensor based on glucose oxidase and beta-galactosidase for specific lactose determination in milk

This paper investigates the development of a biosensor associating two distinct enzymatic activities, that of the beta-galactosidase and that of the glucose oxidase, in order to apply it for the quantitative detection of lactose in milk. To eliminate interferences with glucose, a differential mode of measurement was used. Results show a linear calibration curve for lactose concentration between 60 and 800 μM (0.03 to 0.3 g/L). Tests with real commercial milk samples were carried out to validate the conductometric biosensor.     

Prediction and optimization of electroplated Ni-based coating composition and thickness using central composite design and artificial neural network

Journal of Applied Electrochemistry - The choice of the electroplating conditions of Ni-based alloys has always been a serious research question. In this study, an artificial neural network based...     

On various modeling approaches to radiative heat transfer in pool fires

Six computational methods for solution of the radiative transfer equation in an absorbing-emitting, nonscattering gray medium were compared for a 2-m JP-8 pool fire. The emission temperature and absorption coefficient fields were taken from a synthetic fire due to the lack of a complete set of experimental data for computing radiation for large and fully turbulent fires. These quantities were generated by a code that has been shown to agree well with the limited quantity of relevant data in the literature. Reference solutions to the governing equation were determined using the Monte Carlo method and a ray-tracing scheme with high angular resolution. Solutions using the discrete transfer method (DTM), the discrete ordinates method (DOM) with both S₄ and LC₁₁ quadratures, and a moment model using the M₁ closure were compared to the reference solutions in both isotropic and anisotropic regions of the computational domain. Inside the fire, where radiation is isotropic, all methods gave comparable results with good accuracy. Predictions of DTM agreed well with the reference solutions, which is expected for a technique based on ray tracing. DOM LC₁₁ was shown to be more accurate than the commonly used S₄ quadrature scheme, especially in anisotropic regions of the fire domain. On the other hand, DOM S₄ gives an accurate source term and, in isotropic regions, correct fluxes. The M₁ results agreed well with other solution techniques and were comparable to DOM S₄. This represents the first study where the M₁ method was applied to a combustion problem occurring in a complex three-dimensional geometry. Future applications of M₁ to fires and similar problems are recommended, considering its similar accuracy and the fact that it has significantly lower computational cost than DOM S₄.     

Experimental determination of emission and laminar burning speeds of α-pinene

Several researches have reported that under certain conditions forest fires with normal behavior suddenly start to propagate at unusual and very fast rate of spread. A thermochemical approach, based on the ignition of a Volatile Organic Compounds (VOCs) cloud, has been proposed previously to explain these accelerating forest fires. Indeed, some vegetal species when heated emit volatile substances. We have shown using a flash pyrolysis apparatus that a typical Mediterranean plant, Rosmarinus officinalis, emits eighteen components, mainly α-pinene. Laminar burning speeds and Markstein lengths as well as flame thicknesses of α-pinene/air premixed flames are determined using the spherical expanding flames method. Experiments are carried out in a spherical vessel at atmospheric pressure. The effects of equivalence ratio (0.7–1.4) and unburned gas temperature (353–453 K) are studied. Combustion characteristics are obtained using a nonlinear methodology. A correlation is developed to calculate the laminar burning speeds as a function of equivalence ratio and temperature. The experimental results are compared to the computed ones of JP-10 and n-decane as well as to those found in the literature for these compounds.