An online optimum voltage estimation and real‐time MPP tracking for a PV system

In this paper, a photovoltaic system topology incorporating a new maximum power point tracking (MPPT) controller method is presented. This method uses an autotuning estimator and a PI controller to make the system work in the maximum power point. The controller is formulated based on the bijectivity in the photovoltaic generator characteristic; therefore, if the optimal voltage is reached, this means that the maximum of power is obtained. The proposed MPPT algorithm is implemented on a dSpace DS1104 controller board. In order to demonstrate the efficiency of the proposed algorithm in real time, an experimental setup using a boost converter connected to a resistive load is successfully implemented and studied. The obtained experimental results prove the validity of the proposed MPPT algorithm.     

Adsorptive removal of nitrate and phosphate anions from aqueous solutions using functionalised SBA‐15: Effects of the organic functional group

Adsorption of nitrate and monovalent phosphate anions from aqueous solutions on mono, di‐ and tri‐ammonium‐functionalised mesoporous SBA‐15 silica was investigated. The adsorbents were prepared via a post‐synthesis grafting method, using either 3‐aminopropyltrimethoxysilane (N‐silane) or [1‐(2‐aminoethyl)‐3‐aminopropyl]trimethoxysilane (NN‐silane) or 1‐[3‐(trimethoxysilyl)‐propyl]‐diethylenetriamine (NNN‐silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The nominal loading of amino moieties on the SBA‐15 surface was varied from 5% to 20% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of monoammonium groups on the SBA‐15 adsorbent. Nitrate adsorption capacity increased from 0.34 to 0.66 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent while phosphate adsorption capacity increased from 0.34 to 0.63 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent when the molar ratio organoalkoxysilane/silica was varied from 5% to 20%, respectively. Also, for the same organoalkoxysilane/silica molar ratio of 10%, the adsorption capacity increased with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 0.80, 1.16 and 1.38 mmol ${\rm NO}_{3}^{{-} } /{\rm g}$ adsorbent and 0.72, 0.82 and 1.17 mmol ${\rm H}_{2} {\rm PO}_{4}^{{-} } /{\rm g}$ adsorbent were obtained using mono‐, di‐ and triammonium functionalised SBA‐15 adsorbents, respectively. © 2011 Canadian Society for Chemical Engineering     

Mass transfer of viscous gas flow over porous stretching/shrinking sheet in the presence of slip and mass transpiration

The effect of the mass transpiration parameter on the viscous gas flow past a porous stretching/shrinking sheet in the presence of Navier's slip is investigated, and also, the mass transfer characteristics are examined. The physical flow problem executes the Navier–Stokes and the mass equation, which forms the system of nonlinear partial differential equations. These are transformed via similarity variables into a system of ordinary differential equations. The slip flow model of the total mass transfer on the moving sheet is modeled by introducing gas slip velocity. The total mass transfer on the moving sheet is modeled by inducing slip models of first and second order. Further, the suction which induces the slip velocity as opposed to the surface movement is examined. The mass suction-induced slip forces the adjacent gases to flow in the reverse direction to sheet movement. Thus, the solution space expands with the slip-induced suction and sheet movement. In the mass injection case, the induced slip increases the effect of the fluid flow for sheet movement. Upon all previous flow models, the present investigation is significant due as it investigates the mass transfer of viscous gasses flow past a porous medium in the presence of slip and mass transpiration.     

Impacts of slip and mass transpiration on Newtonian liquid flow over a porous stretching sheet

This article focuses on analytic solutions for Newtonian fluid flow with slip and mass transpiration on a porous stretching sheet using the differential transform method and Pade approximants of an exceptionally nonlinear differential equation. The impacts of different parameters including mass transpiration (suction/injection), Navier's slip, and Darcy number parameters on the velocity of the liquid and tangential stress are discussed. A comprehensive comparison of our results with the previous one in the literature is made, and the results showed good agreement. An investigation is conducted of a combination of magnetic liquids that are conceivably pertinent for wound medicines, skin repair, and astute coatings for natural gadgets. It is found that there is a decrease in the velocity profiles and the boundary layer thickness for the case of suction.     

Synthesis and evaluation of the thermal properties of biosourced poly(ether)ureas and copoly(ether)ureas from 1,4:3,6‐dianhydrohexitols

A new series of poly(ether)ureas were prepared by solution polyaddition of three diamines based on 1,4:3,6‐dianhydrohexitols with three types of diisocyanate. The corresponding poly(ether)ureas were obtained with high yields. They were characterized by various analytical techniques (NMR, TGA and differential thermal analysis, DSC). NMR spectroscopy allowed us to confirm structure type and to optimize reaction conditions and DSC proved the high thermal properties of the products obtained (T_g and T_m in the range 126 ? 158 °C and 235 ? 330 °C respectively). Then, copoly(ether)ureas partially based on commercial diamines were synthesized in order to reduce polymer cost and tune their thermal behaviour. The reactivity of both diamines was evaluated by their incorporation in the polymer by means of NMR spectra. Then their thermal properties were compared with fully commercial diamine based polyureas by DSC studies. © 2014 Society of Chemical Industry     

Thermal convection of MHD Blasius and Sakiadis flow with thermal convective conditions and variable properties

Microsystem Technologies - A theoretical study on the effect of magnetohydrodynamic field on the classical Blasius and Sakiadis flows of heat transfer characteristics with variable conditions and...     

Clouding Behavior of C13EOx (x = 10–19) Micelles in a Wide Range of Salinity and Hardness: Concomitant Effects of Salinity and Degree of Ethoxylation

The effect of salinity and degree of ethoxylation on the cloud point, T_cp, in C₁₃EO_x (x = 10–19) micelles was investigated in distilled water and in the salinity range S = 1.96–196 g L⁻¹. At a fixed x value, the rate dT_cp/dS was given by dT_cp/dS = α _b + β _bS with α _b < 0 and β _b > 0. This trend suggests that dT_cp/dS is the result of two opposing effects, an entirely (negative) surfactant-dependent effect (α _b) and a combined (positive) surfactant-solvent (β _bS)-dependent effect. In addition, the rate dT_cp/dS was found to become increasingly less negative with increasing salinity (dT_cp/dS) < 0), suggesting an overwhelming contribution of the α _b effect as compared to the β _bS effect. On the other hand, at fixed S, the rate was given by dT_cp/dx = α _x + β _xx with α _x > 0 and β _x < 0. This trend also suggests the existence of two opposing effects, a strictly (positive) solvent-dependent effect (α _x) and a concomitant solvent (β _x)-surfactant (x)-dependent effect. Contrary to dT_cp/dS, the rate dT_cp/dx was found to become increasingly less positive with increasing x values (dT_cp/dx > 0), suggesting that α _x is the dominant factor in the surfactants’ susceptibility to be salted in. Both constants α_b and α _x were attributed to a dual temperature-salinity effect on the structure of water molecules not involved in surfactant's hydration. On the other hand, β _b and β _x were associated with the change in the structure of water due to the dehydration of surfactants’ oxyethylene moieties with increasing temperature.     

RadiaLE: A framework for designing and assessing link quality estimators in wireless sensor networks

Stringent cost and energy constraints impose the use of low-cost and low-power radio transceivers in large-scale wireless sensor networks (WSNs). This fact, together with the harsh characteristics of the physical environment, requires a rigorous WSN design. Mechanisms for WSN deployment and topology control, MAC and routing, resource and mobility management, greatly depend on reliable link quality estimators (LQEs). This paper describes the RadiaLE framework, which enables the experimental assessment, design and optimization of LQEs. RadiaLE comprises (i) the hardware components of the WSN testbed and (ii) a software tool for setting-up and controlling the experiments, automating link measurements gathering through packets-statistics collection, and analyzing the collected data, allowing for LQEs evaluation. We also propose a methodology that allows (i) to properly set different types of links and different types of traffic, (ii) to collect rich link measurements, and (iii) to validate LQEs using a holistic and unified approach. To demonstrate the validity and usefulness of RadiaLE, we present two case studies: the characterization of low-power links and a comparison between six representative LQEs. We also extend the second study for evaluating the accuracy of the TOSSIM 2 channel model.