Monitoring Single-point Dressers Using Fuzzy Models

AbstractGrinding causes progressive dulling and glazing of the grinding wheel grains and clogging of the voids on the wheel's surface with ground metal dust particles, which gradually increases the grinding forces. The condition of the grains at the periphery of a grinding wheel strongly influences the damage induced in a ground workpiece. Therefore, truing and dressing must be carried out frequently. Dressing is the process of conditioning the grinding wheel surface to reshape the wheel when it has lost its original shape through wear, giving the tool its original condition of efficiency. Despite the very broad range of dressing tools available today, the single-point diamond dresser is still the most widely used dressing tool due to its great versatility. The aim of this work is to predict the wear level of the single-point dresser based on acoustic emission and vibration signals used as input variables for fuzzy models. Experimental tests were performed with synthetic diamond dressers on a surface-grinding machine equipped with an aluminum oxide grinding wheel. Acoustic emission and vibration sensors were attached to the tool holder and the signals were captured at 2MHz. During the tests, the wear of the diamond tip was measured every 20 passes using a microscope with 10 to 100 X magnification. A study was conducted of the frequency content of the signals, choosing the frequency bands that best correlate with the diamond's wear. Digital band-pass filters were applied to the raw signals, after which two statistics were calculated to serve as the inputs for the fuzzy models. The results indicate that the fuzzy models using the aforementioned signal statistics are highly effective for predicting the wear level of the dresser

Mecanización agraria y empleo en el regadío Extremeño

El progreso tecnológico y la mecanización han provocado siempre, a corto plazo, la amortización de puestos directivos de trabajo, generándose fuerte resistencia entre los anteriormente asalariados. La revuelta de los «canuts», por ejemplo en Francia, oponiéndose a la introducción de las máquinas tejedoras, forma parte de la historia del movimiento obrero del siglo XIX. La mecanización agraria no podía ser, evidentemente, la excepción. El Elemento nuevo, introducido por la presente crisis económica, es la desaparición de empleos alternativos en otras ramas de la producción u otros sectores productivos. La resistencia al desarrollo de la mecanización en el campo cobra actualmente su orina quizás más espectacular en los ataques a las cosechadoras de algodón, pero sobre todo permite la generalización de un estado de ánimo contrario en amplias capas de la población, sobre todo en Andalucía y Extremadura. Hoy no podemos seguir utilizando sencillamente los mismos conceptos productivistas de etapas económicas anteriores, aunque los autores se resisten a una oposición sistemática a la mecanización para la realización de las labores agrícolas. Con Maylor y Ver non (1969) podemos destacar el papel de la empresa y el empresario (en nuestro caso, el agricultor) a la hora de la adopción de las decisiones relativas al cómo y al qué producir. El análisis microeconómico aparece, entonces, como una útil herramienta para analizar la incidencia de un desplazamiento de la función de producción hacia una mayor intensidad en la utilización tanto del capital de explotación como del factor trabajo. En esta línea, el presente trabajo se limita al análisis del regadío extremeño —un buen ejemplo de los sistemas de agricultura del riego mediterráneo (C.M. Portas, 1983) en base a datos recogidos y contrastados por nosotros. Están basados en tiempos reales medios determinados en base a las hojas de cultivo de las fincas colaboradoras del Servicio de Extensión Agraria (S.E.A.) de Badajoz. Las conclusiones que podemos sacar del estudio no pueden, entonces, generalizarse fuera de su contexto y de sus limitaciones. Creemos que nuestros resultados al plantearse en unos términos geográficos específicos no pierden interés, sino que pueden servir, junto con otras investigaciones semejantes, para alcanzar conclusiones generales en un futuro, en un «proceso de enriquecimiento continuo entre lo general y lo particular» como señala Tuñón de Lara (1981). Entre los antecedentes más directos de este estudio, podemos destacar el de PINHEIRO y PORTAS (1980). Su contribución no se ha limitado a la aportación de información y documentación útil para contrastar nuestros resultados con la situación del Alentejo portugués, sino que ha sido constante animador en la elaboración

Cultivos hortícolas industriales en las alternativas de regadío: Productividades y mano de obra empleada.

El cultivo de especies hortícolas con destino industrial se considera como el elemento que puede mejorar a corto plazo la productividad económica y de la mano de obra de las explotaciones de regadío de las Vegas del Guadiana. Se estudian cinco alternativas que incluyen en total siete cultivos diferentes y para dos niveles de explotación (5 ha y 20 ha de superficie). Se calculan las necesidades y distribución anuales de la mano de obra, las productividades y la incidencia de la mecanización de la recolección en las especies hortícolas en que ello es hoy posible. Las diferencias en mano de obra empleada entre las distintas alternativas estudiadas son muy importantes, así como las productividades. La incidencia de la mecanización de la recolección tiende a favorecer la introducción de cultivos hortícolas industriales en explotaciones de mayor dimensión, hoy dedicadas a la producción de grano

Video games are exciting: a European study of videogame‐induced seizures and epilepsy.

Epileptic Disord. 2002 Jun;4(2):121-8. Video games are exciting: a European study of video game-induced seizures and epilepsy. Kasteleijn-Nolst Trenité DG, Martins da Silva A, Ricci S, Rubboli G, Tassinari CA, Lopes J, Bettencourt M, Oosting J, Segers JP. Department of Neurology, Medical Centre Alkmaar, PO Box 501, 1800 AM, The Netherlands. [email protected] Abstract BACKGROUND: Video game seizures have been reported in photosensitive and non-photosensitive patients with epilepsy. The game Super Mario World, has led to many cases of first seizures. We examined whether this game was indeed more provocative than other programs and whether playing the game added to this effect. METHODS: We prospectively investigated 352 patients in four European cities, using a standard protocol including testing of a variety of visual stimuli. We correlated historical data on provocative factors in daily life with electroencephalographic laboratory findings. RESULTS: The video game, Super Mario World proved more epileptogenic than standard TV programs and as provocative as programs with flashing lights and patterns. Most striking was the fact that video game-viewing and-playing on the 50 and 100 Hz TV was significantly more provocative than viewing the standard program (P < 0.001, P < 0.05 respectively). Playing the video game Mario World on a 50 Hz TV, appeared to be significantly more provocative than playing this game on the 100 Hz TV (P < 0.001). Of 163 patients with a history of TV-, VG- or CG-seizures, 85% of them showed epileptiform discharges in response to photic stimulation, 44% to patterns, 59% to 50 Hz TV and 29% to 100 Hz TV. CONCLUSIONS: Children and adolescents with a history of video game seizures are, in the vast majority, photosensitive and should be investigated with standardised photic stimulation. Games and programs with bright background or flashing images are specifically provocative. Playing a video game on a 100 Hz TV is less provocative [published with videosequences]. PMID: 12105074 [PubMed - indexed for MEDLINE

Experimental characterization of combustion in recirculation zone of double-stage swirl chamber

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The focus of the present work is a new Low-NOx combustor configuration to especial application in gas turbine. The combustion happens in two phases; the first one with oxidant deficiency, or fuel rich combustion, and the second one is a fuel lean combustion. This combustion structure allows the conciliation of low NOx emissions and partial oxidation combustion products, as carbon monoxide and unburned hydrocarbons. In the new concept proposed here, these unfavorable combustion conditions for NOx formation are reached through the dynamic control of reactants mixing process into the chamber. However, the success of this strategy depends on the formation of a strong recirculation zone in the secondary chamber and quick-mixing between air, reminiscent fuel and combustion products. So that the present work shows experimental results about the structure of the recirculation zone using Particle Image Velocimetry (PIV) and the combustion dynamics using Planar Laser Inducing Fluorescence (PLIF). Both techniques were applied in the secondary zone of combustion. The conclusion based on the results presented in this paper can be summarized according to the increase of the recirculation zone intensity: 1. the volume occupied by recirculation zone is greater, the transition to reverse flow is more abrupt and the magnitude of the reverse velocity is higher; 2. intensify the vortices formation; 3. the combustion reactions take place in the central region of recirculation zone.dc201

Cyclic carbonate synthesis from CO2and epoxides using zinc(II) complexes of arylhydrazones of β-diketones

Zinc(II) complexes of arylhydrazones of β-diketones (AHBD) were used for the first time as catalysts combined with tetrabutylammonium bromide (TBABr), in the coupling reaction between CO2 and epoxides. The influence of pressure and temperature on cyclic carbonate formation was investigated, as well as the catalytic activity toward different substrates (e.g. styrene oxide, propylene oxide and cyclohexene oxide). The molar ratio between metal complex and TBABr was determined for maximum catalytic activity

COMPARAÇÃO ENTRE FITOTERÁPICOS DE USO TÓPICO NA CICATRIZAÇÃO DE PELE EM EQÜINOS

Foram utilizados seis eqüinos adultos sem raça definida (SRD), com o objetivo de estudar os aspectos macroscópicos e histopatológicos da cicatrização de pele por segunda intenção, em feridas provocadas cirurgicamente e tratadas topicamente por fitoterápicos: barbatimão (Stryphnodendron barbatiman), calêndula (Calendula officinalis) e confrey (Symphytum officinale), tendo a solução salina como controle das demais. Foram feitas quatro lesões de cada lado da região lombar, do lado direito destinadas à macroscopia e do lado esquerdo à análise histopatológica. As lesões foram tratadas diariamente, observando-se a evolução de cada ferida quanto à retração centrípeta e aspecto macroscópico, até a cicatrização completa. Finalizado o experimento, a análise estatística não revelou variações significativas no estudo comparativo dos fitoterápicos. As observações macroscópicas, histopatológica e a retração centrípeta do halo da lesão nos 15 primeiros dias permitiram concluir que o barbatimão revelou efeito benéfico no processo de cicatrização, seguido pela calêndula, sendo os resultados do grupo controle superiores ao confrey. Comparison between phytotherapics on equine wound healing Abstract It has been carried out a study on the macroscopic and histopathologic aspects of equine skin healing by second intention in wounds cirurgically performed and topically treated with phytotherapics: barbatiman (Stryphnodendrom barbattiman), calendula (Calendula officinalis) and confrey (Symphytum officinale) and physiological solution as control. Four lesions were performed in each side of the lumbar area: the ones in the right side for macroscopic observations and the ones on the left side for histopathologic analysis. The lesions were daily treated with the above mentioned phytotherapics. Each wounds was observed in regard to its centripetal contraction and macroscopic aspects until the complete healing. In this model, the statistic analysis did not reveal significant variations in regard to the comparative effect of the phytoterapics. Macroscopic observations, histopathologic analysis and wound area centripetal retraction in the first fifteen days displayed a beneficial effect of barbatiman in the healing process, better than the other treatment groups, followed by calendula. The results displayed by the control group showed to be superior when compared with confrey

Partially premixed flame reactive flow characterization in a bluff body burner

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The present work aims the characterization of a natural gas/air partially premixed flame (PPF) reactive flow in a bluff body burner under laminar conditions in equivalence ratio of 2.1, 1.7 and 1.2. The laboratorial bluff body burner is composed of a central outflow for the premixed reactants and an annular air flow. The latter allows for the stabilization of the flame meanwhile it prevents external aerodynamic influence on the behavior of the flame. For the velocity field measurements, a 2-D Particle Image Velocimetry, PIV, optical diagnostic system is employed. The PIV system comprises of two Nd:YAG lasers with an output wavelength of 532 nm. Titanium dioxide particles, TiO2, are used as seeding particles in the premixed flow. The displacement of the seeding particles between two laser pulses with a known short time difference allows a planar velocity field determination. The stored images are processed using a software integrated with the system in order to obtain the medium velocity field. The software uses statistic data to obtain the correlation between two images acquired in an interval of time of an overlapped interrogation window. The major objective of this study is to examine the flame velocity field of laminar partially premixed natural gas and air flames in rich conditions. Three premixed flames under rich conditions have been studied in the present work with equivalence ratios of 2.1, 1.7 and 1.2 respectively. The study focused on: (1) analyze the instantaneous velocity flow field of the three partially premixed flames, (2) analyze the mean velocity flow field formed from the instantaneous flow fields and (3) analyze the velocity behavior along the center line of the flame.cf201

Excitation Spectra and Thermodynamic Response of Segmented Heisenberg Spin Chains

The spectral and thermodynamic response of segmented quantum spin chains is analyzed using a combination of numerical techniques and finite-size scaling arguments. Various distributions of segment lengths are considered, including the two extreme cases of quenched and annealed averages. As the impurity concentration is increased, it is found that (i) the integrated spectral weight is rapidly reduced, (ii) a pseudo-gap feature opens up at small frequencies, and (iii) at larger frequencies a discrete peak structure emerges, dominated by the contributions of the smallest cluster segments. The corresponding low-temperature thermodynamic response has a divergent contribution due to the odd-site clusters and a sub-dominant exponentially activated component due to the even-site segments whose finite-size gap is responsible for the spectral weight suppression at small frequencies. Based on simple scaling arguments, approximate low-temperature expressions are derived for the uniform susceptibility and the heat capacity. These are shown to be in good agreement with numerical solutions of the Bethe ansatz equations for ensembles of open-end chains.Comment: RevTex, 9 pages with 6 figure