Design of cable-driven parallel manipulators for a specific workspace using interval analysis

In this paper, we present a method, based on interval analysis, to solve the problem of designing cable-driven parallel manipulators (CDPMs) for a desired workspace. The constraint of having positive cable tensions ensuring the equilibrium of the platform has to be satisfied within the given workspace. The proposed algorithm is based on interval analysis, which covers the entire workspace and hence guarantees a singularity-free workspace. Furthermore, the algorithm is capable of finding all possible solutions for this problem and an optimal one is selected according to the user-defined criterion. Two examples are selected to show the efficiency of the developed algorithm in solving this complex problem. The first one deals with the design of a planar CDPM and the second one considers a spatial CDPM. In both cases, the algorithm succeeded to find all possible designs from which the designer can select a solution that fits best his application.     

Drying characteristics and sorption isotherms of silverside fish (Atherina)

The aim of this work was to report drying characteristics and sorption isotherms of silverside fish. The sorption isotherm was determined at four temperature levels 40, 50, 60 and 70 °C and at water activities, ranging from 0.058 to 0.89, using the static gravimetric method. Five sorption models were fitted with the desorption data generated from the gravimetric method. It was found that the Peleg model suitably represents the sorption experimental data in the mentioned investigated ranges of temperature and water activities. Sorption isosteric heat was determined from sorption data using the Clausius–Clapeyron equation. The relationship between the net isosteric heat of sorption and the moisture content was best expressed by the Tsami’s equation. The drying characteristic curve and the drying rate expression of silverside fish have been established from experimental convective drying kinetics.     

Essential oils of Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart collected from three localities of north Tunisia—Krib, Bargou and Nefza—were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin–Ciocalteu method, and antioxidant effectiveness, using the 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p‐cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), γ‐terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC₅₀, ranged from 59 to 80 mg L^?1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg^?1 dry weight, varied from 9.37 to 17.70 g kg^?1 dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p‐cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated. Copyright © 2010 Society of Chemical Industry     

Theoretical study of hydrogen absorption and desorption in Ti1-xZrx Mn1.4 using statistical physics treatment: Microscopic investigation and thermodynamic potential interpretation

Experimental absorption and desorption isotherms of hydrogen in Ti_1-xZr_x Mn_1.4 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys at T = 293 K have been fitted using some theoretical model expressions treated by statistical physics through the grand canonical ensemble. The monolayer model with two types of sites is used to fit and interpret the experimental data. The physicochemical parameters governing the absorption-desorption processes and included into the model expressions could be numerically deduced from the relevant experimental isotherms. Six parameters of the model are fitted, namely the numbers of hydrogen atoms per site n₁ and n₂, the receptor site densities N_1m and N_2m, and the energetic parameters P₁ and P₂. The evolution of these parameters as function of composition x is plotted and explained in correlation with absorption-desorption processes. Finally, the thermo-dynamic potential functions which govern the sorption mechanisms such as internal energy E_int, free enthalpy of Gibbs G_a and entropy S_a were derived from statistical physics calculations based on the model adopted.     

Comparative effects of structural and material parameters variability on Pellet–Cladding Interaction in a PWR fuel rod

In the water pressurised nuclear reactors, the fuel rod cladding is the first barrier against radioactive isotopes release. Its integrity must be demonstrated all along the fuel rod irradiation with increasing strenuous operating conditions. This paper deals with a study made with Electricité de France (EDF) in order to improve the understanding and modelling of the thermomechanical behaviour of fuel rods under these more arduous conditions. The aim of this study is to evaluate the separate influences of structural and material parameters variability on Pellet–Cladding Interaction (PCI). The following parameters have been tested by 3D simulations for a common ramping condition: axial and radial pellet cracks numbers, pellet fragment size, relative fragments displacement, non-symmetrical configuration, pellet–pellet friction and pellet–cladding friction. The second part of the article deals with the development of a model, which gives a better assessment of cladding stress concentration near radial fuel cracks. The implementation in the 1D fuel rod EDF code CYRANO3 and the validation of the model are presented.     

Continuous elliptic and multi-dimensional hyperbolic Darcy-flux finite-volume methods

Elliptic and hyperbolic Darcy-flux approximations are presented. Families of flux-continuous finite-volume methods are investigated for the elliptic full-tensor pressure equation with general discontinuous coefficients. Full pressure continuity across control-volume interfaces is built into the methods leading to an important distinction from the earlier pointwise continuous methods. The families of quasi-positive methods significantly reduce spurious oscillations (induced by earlier schemes) in discrete pressure solutions for strongly anisotropic full-tensor fields. Anisotropy favoring triangulation and non-linear flux splitting are also shown to be effective for computing solutions free of spurious oscillations.Multi-dimensional upwind schemes that reduce cross-wind numerical diffusion induced by the standard upwind scheme are also presented for hyperbolic Darcy-flux approximation.     

Removal of tiemonium methylsulfate,from aqueous solutions using activated carbon prepared from date stones

The retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R²?>?0.98. The adsorption capacity of AC–DS was found to be 42.2?mg?g^?1 at 10°C and 60.5?mg?g^?1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG⁰ and ΔH⁰ confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS⁰.     

High level visual scene classification using background knowledge of objects

Multimedia Tools and Applications - This paper introduces a novel and simple approach of high-level scene classification. Knowing that objects are the essence of any given scene, the proposed...     

Advanced interpretation of hydrogen absorption process in LaMgNi3.6M0.4 (M = Ni,Mn, Al,Co, Cu) alloys using statistical physics treatment

To obtain good economic and environmental benefits, LaMgNi_3.6M_0.4 (M = Al, Mn, Ni, Co, Cu) alloys are investigated for the hydrogen storage. The absorption data of hydrogen in the tested alloys are measured experimentally at 373 K. The hydrogen absorption isotherms are analyzed using three models derived from statistical physics formalism. The adequate model permits to discover significant details about the absorption phenomenon via determining the density of the interstitial sites (D_m), the number of hydrogen atoms per site (n) and the energetic parameter ΔE. The results indicate that multi-atomic (n > 1) and multi-linking (n < 1) phenomena are feasible for hydrogen absorption in LaMgNi_3.6M_0.4 (M = Al, Mn, Ni, Cu, Co) metals. The effects of the substitutions of Ni with Mn, Co, Cu and Al on the hydrogen absorption capacity are investigated. The interaction hydrogen/metal is analyzed by the calculation of the absorption energies. The chemical interaction is the responsible for the hydrogen absorption phenomenon. The contribution of this work is to provide advanced investigations of the hydrogen absorption mechanism in LaMgNi_3.6M_0.4 (M = Al, Mn, Ni, Co, Cu) metals, which are promising alloys for the hydrogen storage.