Crust formation in the blast-furnace stack

Conclusions It was established that the crust forming on the lining of the blast-furnace stack can be divided into two genetic varieties, viz., mass-exchange and metallurgical crusts.The formation of a mass-exchange crust on the stack lining must be prevented by constructing the lining of high-density, thermally and chemically stable refractory minerals. At the same time it is advantageous to create conditions which favor the formation of a protective metallurgical crust on the surface of the lining.Translated from Ogneupory, No, 2, pp. 39–42, February, 1976.     

Creep of oksalon fibres in aqueous sulfuric acid solutions

Conclusions Oksalon yarns do not display an accumulation of plastic deformations in sulfuric acid solutions in stretching in a creep regime, up to a concentration of about 80% by wt.The equilibrium reversible deformation which is reached under conditions of constant tension has a maximum at a sulfuric acid content in the solution of about 70%, and a minimum at 72–73%.The characteristic changes in deformation properties of yarns as a function of the sulfuric acid content of the stretching medium are explained by structural changes which occur in the polyoxadiazole.Stretching Oksalon yarns in a 75% sulfuric acid solution leads to a 25–30% rise in the strength of washed and dried yarnsTranslated from Khimicheskie Volokna, No. 6, pp. 34–36, November–December, 1984.     

Catalytic combustion over platinum group catalysts: fuel-lean versus fuel-rich operation

Performance data are presented for methane oxidation on alumina-supported Pd, Pt, and Rh catalysts under both fuel-rich and fuel-lean conditions. Catalyst activity was measured in a micro-scale isothermal reactor at temperatures between 300 and 800 °C. Non-isothermal (near adiabatic) temperature and reaction data were obtained in a full-length (non-differential) sub-scale reactor operating at high pressure (0.9 MPa) and constant inlet temperature, simulating actual reactor operation in catalytic combustion applications.

Under fuel-lean conditions, Pd catalyst was the most active, although deactivation occurred above 650 °C, with reactivation upon cooling. Rh catalyst also deactivated above 750 °C, but did not reactivate. Pt catalyst was active above 600 °C. Fuel-lean reaction products were CO₂ and H₂O for all three catalysts.

The same catalysts tested under fuel-rich conditions demonstrated much higher activity. In addition, a ‘lightoff’ temperature was found (between 450 and 600 °C), where a stepwise increase in reaction rate was observed. Following ‘lightoff’ partial oxidation products (CO, H₂) appeared in the mixture, and their concentration increased with increasing temperature. All three catalysts exhibited this behavior.

High-pressure (0.9 MPa) sub-scale reactor and combustor data are shown, demonstrating the benefits of fuel-rich operation over the catalyst for ultra-low emissions combustion.     

Gas-discharge He–Ne laser with a wavelength of 1.52 <Emphasis Type="Italic">µ</Emphasis>m for telecommunications systems

Results of a detailed study of a gas-discharge He–Ne laser with a wavelength of 1.52 µm for telecommunications systems are reported. Some important parameters of the laser are measured, such as the laser beam divergence (M ²), the laser power as a function of temperature, laser power stability, noise characteristics of laser radiation, etc. A possibility of laser microminiaturization is mentioned, which is of interest for its application under conditions of intense electromagnetic interference.     

Visual search tree profiling

Understanding how the search space is explored for a given constraint problem – and how it changes for different models, solvers or search strategies – is crucial for efficient solving. Yet programmers often have to rely on the crude aggregate measures of the search that are provided by solvers, or on visualisation tools that can show the search tree, but do not offer sophisticated ways to navigate and analyse it, particularly for large trees. We present an architecture for profiling a constraint programming search that is based on a lightweight instrumentation of the solver. The architecture combines a visualisation of the search tree with various tools for convenient navigation and analysis of the search. These include identifying repeated subtrees, high-level abstraction and navigation of the tree, and the comparison of two search trees. The resulting system is akin to a traditional program profiler, which helps the user to focus on the parts of the execution where an improvement to their program would have the greatest effect.     

Structural changes in molten high-speed steels before atomizing

Molten high-speed steel R6M5F3 has been studied by the x-ray method under different temperature and time conditions. It has been found that transformations of the microheterogeneous structure of the melt with an increase in temperature to 1750°C are associated with a change in atom packing both within microgroups of Fe ( ) and in microregions enriched in carbon (Me₆C, Me_2C MeC). The structural state of high-speed steel powders as a result of temperature-time treatment of the melt varies considerably: There is a high degree of homogeneity due to an increase in the fineness and similarity of carbide-like regions.Institute of Problems of Materials Science, National Academy of Sciences of the Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 8–12, July–August, 1994.     

Isolation and characterization of a novel facultatively alkaliphilic Nitrobacter species, N. alkalicus sp. nov

BACKGROUND: The American College of Rheumatology (ACR) established criteria to discriminate among patients with seven types of vasculitis. Although designated as "classification criteria" for research, these criteria are often used for diagnosis. OBJECTIVE: To examine the operating characteristics of the 1990 ACR classification criteria in the diagnosis of Wegener granulomatosis, giant-cell arteritis, polyarteritis nodosa, and hypersensitivity vasculitis. DESIGN: Prospective cohort study. SETTING: University medical center and Veterans Affairs medical center. PATIENTS: 198 consecutive patients referred to rheumatologists for evaluation of possible vasculitis. Measurements: Blinded chart audits were done to classify patients according to the 1990 ACR classification criteria for Wegener granulomatosis, polyarteritis nodosa, giant-cell arteritis, and hypersensitivity vasculitis on the basis of the patients' initial presentation. Chart audits done 2 to 8 months after baseline provided the patients' final diagnoses, which were considered the gold standard, as in the development of the ACR criteria. Test operating characteristics of the ACR classification criteria were calculated according to 2 x 2 tables for the entire cohort and for only the patients with a final diagnosis of vasculitis. RESULTS: Vasculitis was diagnosed in 51 (26%) patients. Thirty-eight (75%) of 51 patients with vasculitis and 31 (21%) of 147 patients without vasculitis met ACR criteria for one or more types of vasculitis. The positive predictive values for the four vasculitides according to ACR criteria were 17% to 29% for the entire cohort and 29% to 75% for only the patients with a final diagnosis of vasculitis. CONCLUSION: The 1990 ACR classification criteria function poorly in the diagnosis of specific vasculitides.     

Accuracy estimate and optimization techniques for SimRank computation

The measure of similarity between objects is a very useful tool in many areas of computer science, including information retrieval. SimRank is a simple and intuitive measure of this kind, based on a graph-theoretic model. SimRank is typically computed iteratively, in the spirit of PageRank. However, existing work on SimRank lacks accuracy estimation of iterative computation and has discouraging time complexity. In this paper, we present a technique to estimate the accuracy of computing SimRank iteratively. This technique provides a way to find out the number of iterations required to achieve a desired accuracy when computing SimRank. We also present optimization techniques that improve the computational complexity of the iterative algorithm from O(n ⁴) in the worst case to min(O(nl), O(n ³/ log₂ n)), with n denoting the number of objects, and l denoting the number object-to-object relationships. We also introduce a threshold sieving heuristic and its accuracy estimation that further improves the efficiency of the method. As a practical illustration of our techniques, we computed SimRank scores on a subset of English Wikipedia corpus, consisting of the complete set of articles and category links.     

Supervised Learning of Quantizer Codebooks by Information Loss Minimization

This paper proposes a technique for jointly quantizing continuous features and the posterior distributions of their class labels based on minimizing empirical information loss such that the quantizer index of a given feature vector approximates a sufficient statistic for its class label. Informally, the quantized representation retains as much information as possible for classifying the feature vector correctly. We derive an alternating minimization procedure for simultaneously learning codebooks in the euclidean feature space and in the simplex of posterior class distributions. The resulting quantizer can be used to encode unlabeled points outside the training set and to predict their posterior class distributions, and has an elegant interpretation in terms of lossless source coding. The proposed method is validated on synthetic and real data sets and is applied to two diverse problems: learning discriminative visual vocabularies for bag-of-features image classification and image segmentation.