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Development of Mathematical Model for Control Wear in Backup Roll for Hot Strip Mill

Journal of Iron and Steel Research International 2014年第1期21卷 46-51页

作者： R.Servin-Castaeda A.M.Garcia-Lara R.D.Mercado-Solís C.A.Vega-Lebrun uadec university UANL university UPAEP university

The precision of strip flatness depends on several factors; wear of rolls is one of the main variables that have influence on the surface quality of the strip. The wear of the roils represents a complex friction condition, sometimes the wear in the backup roll is not analyzed because the strip is not in contact with the backup roll; however, after several campaigns of rolling, the wear in the backup roll becomes dangerous because the pressure distribution is not uniform. Investigation of mechanism of the surface deterioration of the backup roll for the hot strip rolling is very important for the development of the automatic strip shape control system used in hot strip mills. A mathematical model is developed considering the Hertzian pressure distribution between two cylinders with parallel axes. It is used in real time for calculating the wear in the backup roll and in this manner take deci- sions for preventing finished product reworking or damage of equipments, which result in accidents caused by excessive wear in the backup rolls.

关键词： strip flatness backup roll dress crown rolling campaign

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Fracture energy evaluation on 7075-T651 aluminum alloy welds determined by instrumented impact pendulum

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Transactions of Nonferrous Metals Society of China 2016年第4期26卷 974-983页

作者： R.R.AMBRIZ D.JARAMILLO C.GARCIA F.F.CURIEL Instituto Politécnico Nacional CIITEC-IPN Cerrada de Cecati S/N Col.Sta.Catarina C.P 02250AzcapotzalcaDFMexico Mechanical and Aerospace Engineering Carleton University1125 Colonel By DriveOttawaONK1S 5B6Canada Universidad Autónoma de Coahuila(uadec) Facultad de MetalurgiaCarr 57Km 5MonclovaCoahuilaMexico

By using an instrumented impact pendulum, the force versus time curves of 7075-T651 aluminum welds were obtained from standard Charpy-V samples. Considering the force-time curves and constant impact velocity, the fracture energies for different zones were quantified. A fracture energy improvement for the HAZ(33.6 J) was observed in comparison with the weld metal(7.88 J), and base metal(5.37 J and 7.37 J for longitudinal and transverse directions, respectively). This toughness increment was attributed to the microstructural transformation caused by the thermodynamic instability of η′ precipitates during the welding. Fracture energy for weld metal was higher than that for base metal, probably due to pores created during solidification. Regarding the dynamic yielding force obtained from the force-time curves, an approximation to the dynamic yield strength for weld, HAZ and base metal was determined. Fracture surfaces revealed an intergranular failure for base metal in longitudinal direction, whereas a predominately brittle failure(cleavage) with some insights of ductile characteristics was observed for the transverse direction. In contrast, a ductile failure was observed for weld metal and HAZ.

关键词： 7075-T651 welded joint instrumented Charpy pendulum force-time curve fracture energy dynamic yield strength

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Minimum inhibitory but maximum non-hemolytic concentration of plasma-treated catheters coated with *** and *** extracts

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Plasma Science and Technology 2023年第12期25卷 83-96页

作者： Francisco Javier ALONSO-MONTEMAYOR Miriam Desirée DÁVILA-MEDINA Alejandro ZUGASTI-CRUZ Rosa Idalia NARRO-CÉSPEDES María Guadalupe NEIRA-VELÁZQUEZ AidéSÁENZ-GALINDO Eduardo ALONSO-CAMPOS Autonomous university of Coahuila Saltillo 25280Mexico Center for Research in Applied Chemistry Saltillo 25294Mexico university of Monterrey San Pedro Garza García 66238Mexico

Antibacterial extract-coated catheters are promising alternatives to their conventional counterparts,but their hemocompatibility and thermal stability must be *** bacteria have developed resistance to conventional ***,the minimum inhibitory but non-hemolytic concentration(MIC-NH)and the thermal stability of Larrea tridentata(***)and Origanum vulgare(***)extract-coated catheters were ***,plasma pretreatment was performed to enhance the extract ***,the extract-coated catheters prevent Staphylococcus aureus colonization without causing hemolysis by using *** and *** extracts at MIC-NH(5000 and 2500μg ml~(-1),respectively).Moreover,it has been discovered that the extract coating and plasma treatment improved the thermal stability and the extract adhesion,***,this study provides evidence of alternative antibacterial but non-hemolytic extract-coated catheters.

关键词： antibacterial activity biocompatibility blood-contact device cold plasma nosocomial bacteria

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Polyurethane as substrate for fungal strains

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Advances in Bioscience and Biotechnology 2011年第2期2卷 52-58页

作者： Araceli Loredo-Trevino Gilberto Garcia Abraham Velasco-Tellez Raul Rodriguez-Herrera Cristobal N.Aguilar Group of Bioprocesses.School of Chemistry.university of Coahuila.Saltillo Mexico Research and Development Division.Nemak SA GarciaN.L.Mexico Biotechnology Department.School of Chemistry.university of Coahuila.Saltillo Mexico

Polyurethane is a versatile plastic with several industrial applications in the modern life, but it is considered as a very recalcitrant material. Biodegradation of this plastic has been poorly explored, and most of the studies that have been published focus on bacterial enzymes. In this work, some fungi with the capacity of growing with polyurethane foam as nutrient source were isolated from sands contaminated with this plastic and from DIA/uadec collection, testing their ability to grow on polyurethane as sole carbon and nitrogen sources and their enzymatic activities were determined in specific media as well as their invasion capacity on polyurethane agar plates. 22 fungal strains demonstrated their capacity of growing on polyurethane. Among the enzymatic activities evaluate, the most common was the urease activity (95% of the strains).Protease, esterase and laccase activities were present in 86%, 50% and 36% respectively. The great ability of the isolated fungal strains to use polyurethane foam as nutrient opens an important opportunity to study at detail the biodegradation of this plastic, with clear implications in cell biology and environmental technology.

关键词： Polyurethane Biodegradation Fungal Enzymes In-Plate Screening

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