HEC influence on cement hydration measured by conductometry

Cellulose ethers are of universal use in factory-made mortars, though their influences on mortar properties at a molecular scale are poorly understood. Recent studies dealt with the influence of hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) molecular parameters on cement hydration. It was concluded that the degree of substitution is the most relevant factor on cement hydration kinetics, contrary to the molecular weight. Nevertheless, the major role played by the substitution degree has not been verified for other types of cellulose ethers such as hydroxyethyl cellulose (HEC), which generally possesses a higher hydration retarding capacity compared to HPMC and HEMC. In this frame, a study of the impact of HEC molecular parameters on cement hydration was performed. A negligible influence of the molecular weight was observed. Moreover, the results emphasize that the hydroxyethyl group content mainly determines the delay of cement hydration.     

Super-resolution: a comprehensive survey

Super-resolution, the process of obtaining one or more high-resolution images from one or more low-resolution observations, has been a very attractive research topic over the last two decades. It has found practical applications in many real-world problems in different fields, from satellite and aerial imaging to medical image processing, to facial image analysis, text image analysis, sign and number plates reading, and biometrics recognition, to name a few. This has resulted in many research papers, each developing a new super-resolution algorithm for a specific purpose. The current comprehensive survey provides an overview of most of these published works by grouping them in a broad taxonomy. For each of the groups in the taxonomy, the basic concepts of the algorithms are first explained and then the paths through which each of these groups have evolved are given in detail, by mentioning the contributions of different authors to the basic concepts of each group. Furthermore, common issues in super-resolution algorithms, such as imaging models and registration algorithms, optimization of the cost functions employed, dealing with color information, improvement factors, assessment of super-resolution algorithms, and the most commonly employed databases are discussed.     

The influence of water vapour on the transformation of γ calcium sulphate anhydrite to β anhydrite

The isothermal kinetics of the transformation of γ calcium sulphate anhydrite to β anhydrite have been determined. All the curves obtained have a sigmoidal form. We have also observed an influence of the water vapour pressure on the rate of formation of β anhydrite. On each plot of rate vs. water vapour pressure one observes a maximum whose position shifts to lower values of water vapour pressure when the temperature decreases. The formation of β anhydrite a low temperatures may be explained by the geometry of the water vapour pressure-temperature diagram of the hydrated forms of calcium sulphate, and by the “mineralizing” action of water vapour at or close to saturation.     

Hyper-Spherical Search (HSS) algorithm: a novel meta-heuristic algorithm to optimize nonlinear functions

This paper proposes a novel optimization algorithm called Hyper-Spherical Search (HSS) algorithm. Like other evolutionary algorithms, the proposed algorithm starts with an initial population. Population individuals are of two types: particles and hyper-sphere centers that all together form particle sets. Searching the hyper-sphere inner space made by the hyper-sphere center and its particle is the basis of the proposed evolutionary algorithm. The HSS algorithm hopefully converges to a state at which there exists only one hyper-sphere center, and its particles are at the same position and have the same cost function value as the hyper-sphere center. Applying the proposed algorithm to some benchmark cost functions shows its ability in dealing with different types of optimization problems. The proposed method is compared with the genetic algorithm (GA), particle swarm optimization (PSO) and harmony search algorithm (HSA). The results show that the HSS algorithm has faster convergence and results in better solutions than GA, PSO and HSA.     

Studies in dyeing. II. Effect of crystal modification of disperse dyes on polyester dyeing at 130°C

Four commercial disperse dyes were purified and their different crystal forms were prepared by crystallizing from different solvents or precipitating from their solutions in glacial acetic acid by dilution with water. These forms were found to have different melting points. They were dyed on polyester fibers at 130°C to fiber saturation values by changing the dyebath every 15 min. The effect of pretreatment of the dyes in an aqueous environment at different temperatures (60°, 100°, and 130°C) for 15–60 min in the presence and absence of a dispersing agent on the dye uptake values was also studied. Such treatments are shown to reduce the dye uptake. The implication of these treatments in practical dyeing are pointed out.     

Relative image similarity learning with contextual information for Internet cross-media retrieval

With the fast explosive rate of the amount of image data on the Internet, how to efficiently utilize them in the cross-media scenario becomes an urgent problem. Images are usually accompanied with contextual textual information. These two heterogeneous modalities are mutually reinforcing to make the Internet content more informative. In most cases, visual information can be regarded as an enhanced content of the textual document. To make image-to-image similarity being more consistent with document-to-document similarity, this paper proposes a method to learn image similarities according to the relations of the accompanied textual documents. More specifically, instead of using the static quantitative relations, rank-based learning procedure by employing structural SVM is adopted in this paper, and the ranking structure is established by comparing the relative relations of textual information. The learning results are in more accordance with the human’s recognition. The proposed method in this paper can be used not only for the image-to-image retrieval, but also for cross-modality multimedia, where a query expansion framework is proposed to get more satisfactory results. Extensive experimental evaluations on large scale Internet dataset validate the performance of the proposed methods.     

Effect of composition of metallurgical powder on the slopes and hearths of electric arc furnaces

Summary To reduce the sliding of fettling powders from the slopes of electric furnaces, it is desirable to use powders with not more than 10% of the fraction finer than 0.088 mm, and the SiO₂ content should be about 4.5–6%. Addition to the magnesite powder of coarse dolomite fraction 15-0.5 mm, and also 6–7% coal tar pitch, reduces the mobility of the powders.The rational composition of metallurgical powders used for fettling slopes and hearths of electric arc furnaces largely depends on the grade of steel being melted.The increase in the life of the slopes and hearths of an electric furnace in which stainless steel was being melted, fettled with MPMZ powder, was due to the increase in the content of periclase bonded with melilite and mervinite in the slopes and melilite and forsterite in the hearths.During the melting of steel of changing sorts, the increase in the life of the slopes and hearths, fettling with magnesite-dolomite powders is due to the presence of crystals of periclase bonded mainly with highly refractory dicalcium silicate.When fettling is done with MPMZ powder the structure of the slopes and hearths is identical. The use of chromemagnesite, magnesite-chromite and magnesite-dolomite powders give rise to the formation of a heterogeneous structure in the slopes and hearths which leads to their irregular wearing away.To prolong the service of the hearths and slopes of electric furnaces it is necessary to continue investigating the wear resistance of fettling materials in furnaces of different capacities, where steels of different types are being melted, typifying the life of the powders by the consumption per ton of steel melted, the burn-out profile of the lining, the interrepair periods and other factors.