Analyse de “microantennes” par une méthode temporelle

In this paper, a time domain analysis based on the resolutions of integral equations by the method of moments, is applied to the study of microstrip antennas. At first, the theory will be recalled with the different methods of calculation of antennas characteristics: input impedance, radiation pattern, as well as given approximations. Then, results will be presented and compared to those obtained with frequency methods.     

Retrofitting of reinforced concrete beams using composite laminates

This paper presents the results of an experimental study to investigate the behaviour of structurally damaged full-scale reinforced concrete beams retrofitted with CFRP laminates in shear or in flexure. The main variables considered were the internal reinforcement ratio, position of retrofitting and the length of CFRP. The experimental results, generally, indicate that beams retrofitted in shear and flexure by using CFRP laminates are structurally efficient and are restored to stiffness and strength values nearly equal to or greater than those of the control beams. It was found that the efficiency of the strengthening technique by CFRP in flexure varied depending on the length. The main failure mode in the experimental work was plate debonding in retrofitted beams.     

Use of ion-pairing reversed-phase liquid chromatography in separation of solanidine and solasodine

A method based on ion-pairing reversed-phase liquid chromatography was developed to separate and quantify the total alkaloid content inS. ptycanthum (eastern black nightshade). The method is shown to separate satisfactorily the aglycones and some of the glycoalkaloids. The mobile phase used was aqueous sodium dodecyl sulfate-acetonitrile.     

Severe manifestations in carrier females in X linked retinitis pigmentosa

The aim of this study was to assess the effect of menopause on circadian profile of blood pressure (BP) and heart rate (HR) in the normotensive pre- and postmenopausal women. Systolic BP (SBP), diagnostic BP (DBP) and HR were monitored every 30 min for 48 hrs using noninvasive ambulatory BP monitoring in 24 premenopausal and 40 postmenopausal women. Mean 48-hours, daytime (awake), and nighttime (sleeping) SBP, DBP and HR values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP, DBP and HR were calculated according to the following formula. NRR (%9 = [(daytime mean-nighttime mean)/daytime mean] x 100. The study subjects were then divided into two groups according to the presence (dipper) or absence (nondipper) of a significant reduction in nocturnal BP (> 10%). Mean SBP, DBP and HR measured over 48 hours were similar between the premenopausal and the postmenopausal group. The NRR of DBP and HR in the postmenopausal group were significantly smaller than those in the premenopausal group (17.1 +/- 6.0% vs. 13.5 +/- 7.0%, 241.1 +/- 6.0% vs. 19.8 +/- 9.0%: p < 0.05). There tended to be higher prevalence of nondipper in the postmenopausal (37%) than in the premenopausal group (29%).     

High calcium cementless fly ash binder with low environmental footprint: Optimum Taguchi design

Despite the myriad of research efforts on exploiting fly ash as an alternative binder, its current role in industry is largely restricted to the supplementary use, which enables only partial replacement of conventional portland cement. Herein, we propose an unprecedented binder composite with the promising early-age strength, which is cost-effective and reduces the CO₂ footprint compared with portland cement. The major constituent is fly ash occupying 76.4%-80.3% by the total mass of the constituents, while calcium oxide, nanosilica, and the minimum amounts of sodium-based activators are added to induce the early-age strength development. Optimization of the composition via the Taguchi design of experiments produced the early (7-day) compressive strength of 16.18 MPa. This value is encouraging considering that it is comparable to that of conventional portland cement and that a cementless composition with the minimum amounts of sodium-based activators was employed. The extensive materials analysis demonstrates that the starting Ca/Na molar ratio and the amount of nanosilica play instrumental roles in strength development by influencing the formation of key reaction products, which include the sodium-substituted AFm phase (the U-phase), katoite and portlandite. Overall, the promising early-age strength coupled with the significantly decreased amount of sodium-based chemicals and the reduced CO₂ footprint will lay a foundation for development of low-cost, environmentally friendly binder in diverse industries.     

Analytical modeling nanoparticles-fines reactive transport in porous media saturated with mobile immiscible fluids

This work develops a new analytical solution for the reactive flow of aqueous nanofluid into porous media originally saturated with a mobile aqueous suspension containing fine particles and a mobile oleic-phase. The enhancement of nanoparticles on fines attachment onto rock grains is modeled through the increase of the maximum retention capacity of rock grains. Implementing the splitting technique and stream-function converts the original 3 × 3 system of partial-differential equations into 2 × 2 sub-system of nanoparticles-fines reactive transport, and a lifting equation where only phase saturation appears. Then, method of characteristics is applied to achieve the analytical solution, the validity of which is tested by numerical simulation. The historical profiles of suspended/adsorbed nanoparticles, suspended/attached fines, and phase saturation along 1-D porous medium are reproduced. The impact of injected nanoparticles concentration and carrier fluid saturation on fines attachment is investigated. This work provides a simple-yet-rigorous approach to evaluate nanofluid injection to control fines migration in multiphase flow.     

Merger of Energetic Affinity and Optimal Geometry Provides New Class of Boron Nitride Based Sorbents with Unprecedented Hydrogen Storage Capacity

Hydrogen is an ideal synthetic fuel because it is lightweight, abundant and its oxidation product (water) is environmentally benign. However, its utilization is impeded by the lack of an efficient storage device. A new building block approach is proposed for an exhaustive search of optimal hydrogen uptakes in a series of low density boron nitride (BN) nanoarchitectures via extensive 3868 ab initio‐based multiscale simulations. By probing various geometries, temperatures, pressures, and doping ratios, these results demonstrate a maximum uptake of 8.65 wt% at 300 K, the highest hydrogen uptake on sorbents at room temperature without doping. Li⁺ doping of the nanoarchitectures offers a set of optimal combinations of gravimetric and volumetric uptakes, surpassing the US Department of Energy targets. These findings suggest that the merger of energetic affinity and optimal geometry in BN building blocks overcomes the intrinsic limitations of sorbent materials, putting hybrid BN nanoarchitectures on equal footing with hydrides while demonstrating a superior capacity‐kinetics–thermodynamics relationship.     

Simultaneously achievement of high recoverable energy density and efficiency in sodium niobate-based ceramics

Journal of Materials Science: Materials in Electronics - Single lead-free Na0.73Bi0.09(Nb1???xTax)O3 (x?=?0, 0.10, 0.20, 0.30, and 0.40) ceramic phases were processed...     

Enhancing the prediction of type 2 diabetes mellitus using sparse balanced SVM

Multimedia Tools and Applications - The natural population-based prediction of type 2 diabetes is costly since it needs a high number of resources. Even though much research has used machine...