A new generalised α scale spaces quadrature filters

The α   scale spaces is a recent theory that open new possibilities of phase-based image processing. It is a parameterised class (α∈]0,1])$(\alpha \in ]0,1\left]\right)$ of linear scale space representations, which allows a continuous connection beyond the well-known Gaussian scale space (α=1$\alpha =1$). In this paper, we make use of this unified representation to derive new families of band pass quadrature filters, built from derivatives and difference of the α scale space generating kernels. This construction leads to generalised α kernel filters including the commonly known families derived from the Gaussian and the Poisson kernels. The properties of each family are first studied and then experiments on one- and two-dimensional signals are shown to exemplify how the suggested filters can be used for edge detection. This work is complemented by an experimental evaluation, which demonstrates that the new proposed filters are a good alternative to the commonly used Log-Gabor filter.     

Hot carrier reliability of RF N- LDMOS for S Band radar application

This paper presents an innovative reliability bench specifically dedicated to high RF power device lifetime tests under pulse conditions for radar application. A base-station dedicated LDMOS transistor has been chosen for RF lifetests and a complete device electric characterization has been performed. A whole review of its critical electrical parameters after accelerated ageing tests is proposed and discussed. This study tend to explain the physical degradation mechanisms occurred during RF life-tests by means of 2D ATLAS-SILVACO simulations. Finally, the paper demonstrates that N-LDMOS degradation is linked to hot carriers generated interface states (traps) and trapped electrons, which results in a build up of negative charge at Si/SiO2 interface. More interface states are created at low temperature due to a located maximum impact ionization rate at the gate edge.     

Local maximum likelihood segmentation of echocardiographic images with Rayleigh distribution

In order to interpret ultrasound images, it is important to understand their formation and the properties that affect them, especially speckle noise. This image texture, or speckle, is a correlated and multiplicative noise that inherently occurs in all types of coherent imaging systems. Indeed, its statistics depend on the density and on the type of scatterers in the tissues. This paper presents a new method for echocardiographic images segmentation in a variational level set framework. A partial differential equation-based flow is designed locally in order to achieve a maximum likelihood segmentation of the region of interest. A Rayleigh probability distribution is considered to model the local B-mode ultrasound images intensities. In order to confront more the speckle noise and local changes of intensity, the proposed local region term is combined with a local phase-based geodesic active contours term. Comparison results on natural and simulated images show that the proposed model is robust to attenuations and captures well the low-contrast boundaries.     

Local commute-time guided MDS for 3D non-rigid object retrieval

In this paper, we propose a 3D non-rigid shape retrieval method based on canonical shape analysis. Our main idea is to transform the problem of non-rigid shape retrieval into a rigid shape retrieval problem via the well-known multidimensional scaling (MDS) approach and random walk on graphs. We first segment the non-rigid shape into local partitions based on its salient features. Then, we calculate a local MDS problem for each partition, where the local commute time distance is used as weighting function in order to preserve local shape details. Finally, we aggregate the set of local MDS problems as a global constrained problem. The constraint is formulated using the biharmonic function between local salient features. In contrast to MDS method, the proposed local MDS is computationally efficient, parameters free and gives isometry-invariant forms with minimum features distortion. Due to these advantageous properties, the proposed method achieved good retrieval accuracy on non-rigid shape benchmark datasets.     

Design optimization of a solar tower power plant heliostat field by considering different heliostat shapes

The present study focuses on the optimization of solar tower power plant heliostat field by considering different heliostat shapes including rectangular, square, pentagon, hexagon, heptagon, octagon, and circular heliostat shapes. The optimization is carried out using an in-house developed code-based MATLAB program. The developed in-house code is validated first on a well-known PS10 Solar Thermal Power plant having rectangular heliostats shape and the resulting yearly unweighted heliostat field efficiency of about 64.43% could be obtained. The optimized PS10 heliostat field using different heliostat shapes showed that the circular and octagon heliostat shapes provide better efficiency with minimum land area. The yearly efficiency is increased from 69.65% for the rectangular heliostat shape to 70.96% and 71% for the octagon and circular shapes, respectively. In addition, the calculated field area (land area) is reduced for the case of circular and octagon heliostat shapes with a gain of about 11.10% and 10.93% (about 42.0436 × 10³ and 41.4036 × 10³ m²), respectively, in comparison with the PS10 field area.     

Tractability through symmetries in propositional calculus

Many propositional calculus problems — for example the Ramsey or the pigeon-hole problems — can quite naturally be represented by a small set of first-order logical clauses which becomes a very large set of propositional clauses when we substitute the variables by the constants of the domainD. In many cases the set of clauses contains several symmetries, i.e. the set of clauses remains invariant under certain permutations of variable names. We show how we can shorten the proof of such problems. We first present an algorithm which detects the symmetries and then we explain how the symmetries are introduced and used in the following methods: SLRI, Davis and Putnam and semantic evaluation. Symmetries have been used to obtain results on many known problems, such as the pigeonhole, Schur's lemma, Ramsey's, the eight queen, etc. The most interesting one is that we have been able to prove for the first time the unsatisfiability of Ramsey's problem (17 vertices and three colors) which has been the subject of much research.     

Study of RF N LDMOS critical electrical parameter drifts after a thermal and electrical ageing in pulsed RF

An innovative reliability test bench dedicated to RF power devices is currently implemented. This bench allows to apply both electric and thermal stress for lifetime test under radar pulsed RF conditions. This paper presents the first investigation findings of critical electrical parameter degradations after thermal and electrical ageing. It shows that the tracking of a set of parameters (drain–source current, on-state resistance, threshold voltage, feedback capacitance and transconductance) can give insight into the hot carrier injection phenomenon for a RF n⁻ channel lateral DMOS (N⁻ LDMOS) working under pulsed conditions.     

Formulation Studies on [2-amino-5-bromo-phenyl-4(3)-pyrimidinone] (ABPP), an Interferon Inducer. Anti-Cancerogenic Agent

The apparent solubility of ABPP in aqueous solutions suitable for intravenous use was increased by cosolvent systems.

The solubility of ABPP was determined as a function of pH and concentration of NaOH, NaCl, Na₂CO₃ and co-solvents. Partition coefficient of ABPP in Octanol/water systems were also determined at various pH values. Solubility data and spectrophotemetric methods were used to determine the pKa values. The solubility of the compound increased at lower and higher pHs with increasing NaOH and Na₂CO₃ concentrations and increasing PEG 400, Propylene glycol, dimethylformamide and dimethylacetamide concentrations but decreased with the introduction of NaCl to the solution. The apparent partition coefficient of ABPP showed similar but reversed dependence to the pH of the buffer system.

From these results, suitable formulations for use as parenteral solutions are proposed. The increase in the apparent aqueous solubility of ABPP in such formulations my increase up to 800-fold, depending upon the pH and solvent concentrations. The compound was found to be stable for at least 6 months (experimental period) under normal shelf conditions when formulated for i. v. administration. When the suggested formulation injected intravenously into rabbits, at three different dose levels, the elimination half life of ABPP appeared not be dose dependent although data showed a straight line relationship between the area under the curve and dose and Cpmax ad dose.     

Removal of organic load and phenolic compounds from olive mill wastewater by Fenton oxidation with zero-valent iron

Pre-treatment of olive mill wastewater (OMW) by Fenton Oxidation with zero-valent iron and hydrogen peroxide was investigated to improve phenolic compounds degradation and the chemical oxygen demand (COD) removal. Experimental procedure is performed with diluted OMW with COD 19 g/L and pH 5.2. The application of zero-valent Fe/H₂O₂ procedure allows high removal efficiency of pollutants from OMW. The optimal experimental conditions were found to be continuous presence of iron metal, acidic pH (2–4) and 1 M hydrogen peroxide solution. The experimental results show that the removal of 1 g of COD need 0.06 M of H₂O₂. At pH 1, the maximum COD removal (78%) is achieved after 1 h. Therefore, with a pH value within 2 and 4 the maximum COD removal reached 92%. Phenolic compounds are identified in treated and untreated OMW by gas chromatography coupled to mass spectrometry (GC–MS). The result shows a total degradation of phenolic compounds and an increasing biodegradability of treated OMW.