Application of genetic algorithm to color recipe formulation using reactive and direct dyestuffs mixtures

Color reproduction is a science in constant development. In this article, a new model to solve the color recipe prediction problem using a genetic algorithm is proposed. The objective is to optimize the color recipe prediction stage by determining the dyes to use in a mixture and their respective proportions to reproduce the target color. Two ranges of dyes were used for dyeing 100% cotton woven fabrics: three reactive dyes (CI Reactive Red 238, CI Reactive Yellow 145, and CI Reactive Blue 235) and four direct dyes (CI Direct Orange 34, CI Direct Red 227, CI Direct Blue 85, and CI Direct Black 22). The criterion of optimization, in reproducing the desired shades, is to minimize the CMC color difference between the desired reference color and the color resulting of the predicted recipe. The proposed algorithm revealed good results with small CMC color differences between target and reproduced colors. The effectiveness of the algorithm was also evaluated and proven by calculating errors between the predicted concentrations in the proposed recipes and the actual concentrations.     

Development of heat-resistant anticorrosion urethane siloxane paints

Three two-layer heat-resistant and anticorrosion paints have been formulated from urethane siloxane binder and traditional anticorrosion pigments such as micaceous iron oxide (MIO), zinc phosphate (ZP), and aluminum oxide. These pigments were used as the dominant components of different undercoats or topcoats. Heat-resistant pigments such as silicon nitride and glass-spheres were used in the composition of the topcoats. Thermogravimetric analysis of paints shows that the paint with ZP as dominant component of the undercoat have the highest heat-resistance and stability in inert gas and oxygen. The paint with a combination of MIO and ZP has the best hardness as well as the best protective and anticorrosion properties based on the electrochemical impedance spectroscopy. A maximum synergic effect of the properties of pigments seems to appear in this paint. Surface morphology of paints was studied by means of scanning electron microscopy. Heated at different temperatures and for several hours, paint containing MIO as the dominant component in the undercoat exhibits the best mechanical and adhesion properties.     

Reactive sintering of boron-doped Ni76Al24 intermetallic

A preliminary investigation into the formation of boron-doped nickel-rich Ni₃Al with boron additions up to 2 wt% (i.e. to levels above the equilibrium solid solubility limit of boron in Ni₃Al) from elemental powders by reaction synthesis was carried out. The application of reaction synthesis was seen as a low-energy alternative to the production of Ni₃Al/boride composite suitable for wear applications. X-ray diffraction, Neutron diffraction, SEM/EDS,WDS, Image analysis, Archimedes principle and Rockwell hardness measurements; were used to study the effect of boron addition on the final microstructure, average grain size, bulk density and hardness of as-prepared Ni₇₆Al₂₄. Up to 0.3 wt% boron content, the microstructure consisted of single-phase Ni₃Al, however, at a boron content of 0.5 wt% an apparent transition from a single phase microstructure to a two-phase intermetallic/boride composite microstructure was observed, which dominated when the boron content increased, up to 2 wt%. The two-phase microstructure was identified as Ni₃Al (particles) within an Ni₄₁Al₅B₁₂ boride matrix, with no remaining un-reacted boron. The boron addition was found to increase the Rockwell hardness of Ni₃Al via two mechanisms. Below the solubility limit, the increase in hardness was due to solution hardening. Above 0.5 wt%B, solution hardening in addition to the formation of the harder boride phase, were found to amount to up to 50% increase in the hardness compared with boron free Ni₃Al. The extrusion of semi-molten beads at the surface of the compact at high B-content may be a limiting factor, in the formation of Ni₃Al/boride composites via this route.     

Prediction of grain boundary stress fields and microcrack initiation induced by slip band impingement

Slip localization is widely observed in metallic polycrystals undergoing cyclic deformation or post-irradiation tensile deformation, whatever their crystallographic structure. Hence, strong strain localization occurs in thin slip bands (SBs) inducing by the way local stress concentrations at their intersections with grain boundaries (GBs). Many GB stress field formulae based on the dislocation pile-up theory have been proposed since the pionnering work of Stroh and others. These allow the use of the Griffith criterion for prediction GB fracture initiation. However, recent observations show that assuming that slip is localized on a single atomic plane leads to unrealistic results. In fact, a large number of slip planes are plastically activated and then finite slip band thickness should be accounted for. Numerous crystalline finite element (FE) computations have been carried out using considering a slip bands with low critical resolved shear stress embedded in an elastic matrix. The computed GB normal and shear stress fields:

are considerable lower than the pile-up ones and exhibit strong dependency on the slip band thickness close to the SB corner

but are in fair agreement with the solution predicted by the pile-up theory far away.

Since the pile-up theory leads to the overestimation of the local GB stress fields, the main goal of the current paper is to perform analytical model of GB stress components based upon FE calculations. The effect of various parameters can be understood in the framework of matching asymptotic expansions which is usually applied to cracks with V notches of finite thickness. Finally, the predicted remote stresses to GB fracture in pre-irradiated austenitic stainless steels subjected to tensile loading in various environment are compared to experimental data and the pile-up based predictions.     

Properties of metakaolin based geopolymer incorporating calcium carbonate

An alkaline solution, thermally activated kaolinite clay and a mineral additive (calcium carbonate) were mixed with the aim to elaborate a geopolymer material with physical and mechanical properties comparable to those of classical construction materials.The starting reagents were characterized by quantitative chemical analyses (XRF), mineralogical analyses (XRD), thermal gravimetric analyses (TGA), and grain size distribution measurements. The setting of the mixture (polymerization) was implemented by measuring the evolution of the viscosity as a function of time at different temperatures.The geopolymers were synthesized at a temperature of 40 °C. The investigation of the mechanical behavior reveals that these materials display acceptable characteristics: the flexural and compression strength are around 4.6 and 26 MPa respectively, for an added calcium carbonate over dry matter ration up to 12% by weight.The promising results exposed in this paper show that the geopolymer formulations can be adapted for applications in construction and civil engineering structures as an alternative to conventional materials.     

Silver sulfide nanoparticle assembly obtained by reacting an assembled silver nanoparticle template with hydrogen sulfide gas

A fast, simple procedure is described for obtaining an assembly of silver sulfide nanoparticles (Ag(2)S NPs) on a glass substrate through reaction of a template of an assembled layer of silver nanoparticles (Ag NPs) with hydrogen sulfide (H(2)S) gas. The Ag NP template was prepared by assembling a monolayer of spherical Ag NPs (mean diameter of 7.4?nm) on a polyethylenimine-treated glass substrate. Exposure to pure H(2)S for 10?min converted the Ag NPs of the template to Ag(2)S NPs. The resulting Ag(2)S NP assembly, which retains the template nanostructure and particle distribution, was characterized by optical absorption spectroscopy, atomic force microscopy, transmission electron microscopy (TEM), scanning high resolution TEM, energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The Ag(2)S NPs have a crystal structure of monoclinic acanthite, and while they retained the spherical shape of the original Ag NPs, their mean particle size increased to 8.4?nm due to changes to the crystal structure when the Ag NPs are converted into Ag(2)S NPs. The measured optical absorption edge of the Ag(2)S NP assembly indicated an indirect interband transition with a band gap energy of 1.71?eV. The Ag(2)S NP assembly absorbed light with wavelengths below 725?nm, and the absorbance increased monotonically toward the UV region.     

Range image segmentation using local approximation of scan lines with application to CAD model acquisition

Abstract. Automatic acquisition of CAD models from existing objects requires accurate extraction of geometric and topological information from the input data. This paper presents a range image segmentation method based on local approximation of scan lines. The method employs edge models that are capable of detecting noise pixels as well as position and orientation discontinuities of varying strengths. Region-based techniques are then used to achieve a complete segmentation. Finally, a geometric representation of the scene, in the form of a surface CAD model, is produced. Experimental results on a large number of real range images acquired by different range sensors demonstrate the efficiency and robustness of the method. Received: 1 August 2000 / Accepted: 23 January 2002 Correspondence to: I. Khalifa     

Charged particle equilibrium effects on the electron absorbed fraction in the extrathoracic airways

Estimates of the dose to the extrathoracic airway (nasal vestibule) from inhaled beta-emitting radionuclides, obtained using the respiratory tract model presented in Publication 66 of the International Commission on Radiological Protection, frequently predict that the basal cells in this region are the most highly irradiated tissues of the body. The dose to the basal cells is averaged over a layer of tissue 10 microm thick located at a depth of 40 microm into the airway assuming that charged particle equilibrium exists. Since the target (basal cell layer) is very small and thin (10 cm(2) area and 10 microm thickness), charged particle equilibrium does not exist. In this work the effect on the absorbed fraction of the lack of charged particle equilibrium is investigated.