Search results for "Control and Systems Engineering"
showing 10 items of 994 documents
Zinc removal in anaerobic sulphate-reducing liquid substrate process
2002
Abstract Zinc and sulphate removal from synthetic wastewater was investigated by using four laboratory parallel upflow-mode reactors (referred as R1 to R4; R1 contained carriers to retain biomass, whereas R2–R4 were operated as suspended reactors). All reactors were inoculated with anaerobically digested cow manure. R1 and R2 were first fed with glucose- and sulphate-containing feed for 48 days after which all four reactors were fed with wastewater containing 50 mg l−1 of zinc in R1–R3 and 200 mg l−1 in R4 and operated for 96 days. In all reactors, hydraulic retention time, organic loading rate, and sulphate load were 5–6 d, 0.2–0.4 kg COD m−3 d−1 and 3.3–3.8 g SO4 l−1 d−1, respectively, wh…
Thermodynamic approach of supercontinuum generation
2009
International audience; This paper is aimed at providing an overview on recent theoretical and experimental works in which a thermodynamic description of the incoherent regime of supercontinuum generation has been formulated. On the basis of the wave turbulence theory, we show that this highly nonlinear and quasi-continuous-wave regime of supercontinuum generation is characterized by two different phenomena. (i) A process of optical wave thermalization ruled by the four-wave mixing effects: The spectral broadening inherent to supercontinuum generation is shown to result from the natural tendency of the optical field to reach its thermodynamic equilibrium state, i. e., the state of maximum n…
Comparison between grain-size analyses using laser diffraction and sedimentation methods
2010
A comparison between laser diffraction method (LDM) and the sieve-hydrometer method (SHM) was carried out for 228 soil samples representing a different texture classification sampled in a Sicilian basin. The analysis demonstrated that the sand content measured by SHM can be assumed equal to that determined by LDM technique, while the clay fraction measured by LDM was lower than that measured by the SHM. A set of equations to transform LDM results to SHM results was proposed. The influence of the LDM measurements of clay on the estimated percentage of silt + very fine sand particles (particle diameter ranging from 0.002 mm to 0.1 mm), which is useful for estimating soil erodibility, was also…
STRUCTURE AND MAGNETIC PROPERTIES OF COBALT FERRITE PARTICLES PRODUCED BY METHOD OF PYROLYTIC SYNTHESIS
2008
ABSTRACT Magnetic fine particles of cobalt ferrite have been prepared by method of pyrolytic synthesis. X-ray diffraction confirmed the formation of single-phase cobalt ferrite nanoparticles in the range 6–50 nm. The size of the particles varies depending on matrix dispersity and mass content in the organic precursors. A large coercivity observed to be small for smaller single-domain particles due to superparamagnetic behavior.
Elastic Properties of Barium Zirconate Titanate Ceramics
2011
In the paper the influence of zirconium admixture on the structure and material constants of polycrystalline ferroelectric materials BaZrxTi1-xO3 (BZT) was examined. The barium zirconate titanate samples were prepared by a conventional solid state reaction method. A single phase with perovskite structure of the samples, was identified by an X-Ray diffraction technique at room temperature. The performed EDS study revealed that the samples were perfectly sintered and the material was chemically homogeneous. The dependence of shear modulus G on sample composition is similar to the respective dependence of Young's modulus E, whereas the Poisson's ratio ν decreases with the increase in zirconium…
Differential scanning calorimetry investigation of phase transition in $BaZr_{x}Ti_{1-x}O_{3}$
2009
ABSTRACT Lead-free BaZrxTi1-xO3 (x = 0; 0.025; 0.125) ceramics have been obtained by a conventional method. A single-phase perovskite structure of the ceramics was identified by the X-ray diffraction method. EDS analysis, performed for the individual grains of the tested sample, showed a good homogeneous distribution of all elements throughout the grains. The thermal behaviour of BaZrxTi1-xO3 (x = 0; 0.025; 0.125) ceramics was studied using the Differential Scanning Calorimetry (DSC). Measurements showed the influence of Zr addition on the character of phase transition in the BaTiO3 structure. The results were compared with these ones obtained for pure BaTiO3.
Optimal shape design and unilateral boundary value problems: Part II
2007
In the first part we give a general existence theorem and a regularization method for an optimal control problem where the control is a domain in R″ and where the system is governed by a state relation which includes differential equations as well as inequalities. In the second part applications for optimal shape design problems governed by the Dirichlet-Signorini boundary value problem are presented. Several numerical examples are included.
Extensions and intentions in the rough set theory
1998
Abstract The approach to rough set theory proposed in this paper is based on the mutual correspondence of the concepts of extension and intension. It is different from the well-known approaches in the literature in that the upper approximations and the lower approximations of ‘unknown’ sets are considered as certain families of ‘known’ sets. This approach makes it possible to formulate necessary and sufficient conditions for the existence of operations on rough sets, which are analogous to classical operations on sets. The basic results presented in this paper, based on certain ideas of the second author, were formulated by the first author in his doctoral dissertation prepared under the su…
Best Proximity Point Results in Non-Archimedean Fuzzy Metric Spaces
2013
We consider the problem of finding a best proximity point which achieves the minimum distance between two nonempty sets in a non-Archimedean fuzzy metric space. First we prove the existence and uniqueness of the best proximity point by using di fferent contractive conditions, then we present some examples to support our best proximity point theorems.
Tensor product multiresolution analysis with error control for compact image representation
2002
A class of multiresolution representations based on nonlinear prediction is studied in the multivariate context based on tensor product strategies. In contrast to standard linear wavelet transforms, these representations cannot be thought of as a change of basis, and the error induced by thresholding or quantizing the coefficients requires a different analysis. We propose specific error control algorithms which ensure a prescribed accuracy in various norms when performing such operations on the coefficients. These algorithms are compared with standard thresholding, for synthetic and real images.