Production Technology of Wear-Resistant Magnesian Refractories in the Context of Contemporary Trends in Developing Steel Production and Other Processes,Ecology, Resource Saving,and Computerization

The physicochemical principles of technology and wear-resistance of magnesian refractories are considered in relation to the problems of resource saving, sustainable development, and environmentally safe production. A new concept of resource saving in the framework of the composition-structure-properties-technology-design-service conditions-ecology-computerization system is proposed as the main line of research for the 21st century.     

Optimal search path for service in the presence of disruptions

We consider the following basic search path problem: a customer residing at a node of a network needs to obtain service from one of the facilities; facility locations are known and fixed. Facilities may become inoperational with certain probability; the state of the facility only becomes known when the facility is visited. Customer travel stops when the first operational facility is found. The objective is to minimize the expected total travel distance.     

Current state of steel-melting production and the technology for and raw-materials base of magnesia refractories in Ukraine

The state of production of magnesia refractories is considered. Ukraine does not produce promising advanced magnesia refractories (periclase-carbon, dolomite-periclase-carbon, and periclase-spinel). Periclase-chromite and chromite-periclase refractories are produced on the basis of imported raw materials of various grades. The technical level of the used equipment does not meet current requirements. The raw-materials base is underdeveloped. In order to bring the production of Ukrainian magnesia refractories to a competitive level have to attain the quality of the world counterparts at a cost 20–30% lower than the world level. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 4, pp. 32–35, April, 1998. For the beginning of the article see No. 3 of 1998.     

Application of magnesia concrete and brick for the lining of electric furnaces

Conclusions Self-setting magnesia concrete and solutions are applicable for the lining of electric furnaces in the form of blocks.The testing of magnesia concrete and basic brick blocks is recommended on an industrial level for the verification of their effectiveness in electric furnaces of different capacity.     

Morphological segmentation and partial volume analysis for volumetry of solid pulmonary lesions in thoracic CT scans

Volumetric growth assessment of pulmonary lesions is crucial to both lung cancer screening and oncological therapy monitoring. While several methods for small pulmonary nodules have previously been presented, the segmentation of larger tumors that appear frequently in oncological patients and are more likely to be complexly interconnected with lung morphology has not yet received much attention. We present a fast, automated segmentation method that is based on morphological processing and is suitable for both small and large lesions. In addition, the proposed approach addresses clinical challenges to volume assessment such as variations in imaging protocol or inspiration state by introducing a method of segmentation-based partial volume analysis (SPVA) that follows on the segmentation procedure. Accuracy and reproducibility studies were performed to evaluate the new algorithms. In vivo interobserver and interscan studies on low-dose data from eight clinical metastasis patients revealed that clinically significant volume change can be detected reliably and with negligible computation time by the presented methods. In addition, phantom studies were conducted. Based on the segmentation performed with the proposed method, the performance of the SPVA volumetry method was compared with the conventional technique on a phantom that was scanned with different dosages and reconstructed with varying parameters. Both systematic and absolute errors were shown to be reduced substantially by the SPVA method. The method was especially successful in accounting for slice thickness and reconstruction kernel variations, where the median error was more than halved in comparison to the conventional approach.     

Unfired brick from magnesite-chromite concrete for open-hearth furnace building

Conclusions Unfired brick made of magnesite-chromite concrete with periclase cement, tested in several parts of open-hearth furnaces, showed the same resistance as fired magnesite or chrome-magnesite refractories.Unfired magnesite-chromite brick made of concrete can be used for building structures with air-setting, water-containing cement instead of iron plates.It is necessary to organize the industrial production of unfired goods made of magnesite-chromite concrete using the method developed by UNIIO for extensive testing and subsequent use in open-hearth furnaces.     

Magnesite-spinel roof products with sintered magnesia-alumina spinel in the batch

Conclusions The basic production parameters were determined for magnesite-spinel refractories using sintered spinel. At the Experimental Factory of the Ukrainian Scientific-Research Institute of Refractories products were prepared having an open porosity of 9.3–12.5%, a compressive strength of 550–820 kg/cm², and a thermal shock resistance of more than 15 water-heat cycles.Petrographic studies established that a typical feature for magnesite-spinel refractories is the irregular granular structure and the development in large quantities of dense contacts between the grains and sections of the spinel and periclase bond, sometimes with partial (mutual) intergrowths. These features apparently determine the high ceramic and service properties of these refractories.Translated from Ogneupory, No. 7, pp. 40–46, July, 1972.     

Locating service facilities to reduce lost demand

We analyze the problem of locating a set of service facilities on a network when the demand for service is stochastic and congestion may arise at the facilities. We consider two potential sources of lost demand: (i) demand lost due to insufficient coverage; and (ii) demand lost due to congestion. Demand loss due to insufficient coverage arises when a facility is located too far away from customer locations. The amount of demand lost is modeled as an increasing function of the travel distance. The second source of lost demand arises when the queue at a facility becomes too long. It is modeled as the proportion of balking customers in a Markovian queue with a fixed buffer length. The objective is to find the minimum number of facilities, and their locations, so that the amount of demand lost from either source does not exceed certain pre-set levels. After formulating the model, we derive and investigate several different integer programming formulations, focusing in particular on alternative representations of closest assignment constraints. We also investigate a wide variety of heuristic approaches, ranging from simple greedy-type heuristics, to heuristics based on time-limited branch and bound, tabu search, and random adaptive search heuristics. The results of an extensive set of computational experiments are presented and discussed.