Thermal Analysis of a Directly Grid-Fed Induction Machine with Floating Neutral Point, Operating under Unbalanced Voltage Conditions

Significant changes may occur in the thermal behavior of a directly grid-fed induction machine when subjected to unbalances in the voltage supply. This article studies and analyzes the thermal behavior of a low power, three-phase, squirrel-cage induction motor, connected in star configuration with floating neutral point, when subjected to different levels of unbalanced voltage. The dependence of the thermal motor behavior on the severity level of the unbalance is studied and analyzed. In addition to amplitude unbalances, this article focuses on the effects of phase unbalances, as well, which were not addressed in detail in previous published studies. Moreover, situations of mixed unbalance, where amplitude and phase unbalances occur simultaneously, are also studied. The finite element method was used to simulate the thermal behavior of the machine. The experimental setup consists of a three-phase programmable AC power supply, suitable to precisely emulate unbalanced conditions that may occur in real-scale power systems, supplying a 2.2 kW induction motor. Experimental data were acquired resorting to resistance temperature detectors PT100, placed in the machine phase whose supply current value changed the most. Finally, the simulation results are verified and critically discussed through experimentally obtained results.info:eu-repo/semantics/publishedVersio

Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions

[EN] A study on the sources of variability in the measurement of particle size distribution using a two-stage dilution system and an engine exhaust particle sizer was conducted to obtain a comprehensive and repeatable methodology that can be used to measure the particle size distribution of aerosols emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement method; an evaluation of the influence of sampling factors, such as dilution system pre-conditioning; and a study of the effects of the dilution conditions, such as the dilution ratio and the dilution air temperature. An examination of the type and degree of influence of each studied factor is presented, recommendations for reducing variability are given and critical parameter values are identified to develop a highly reliable measurement methodology that could be applied to further studies on the effect of engine operating parameters on exhaust particle size distributions. © 2011 IOP Publishing Ltd.The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain.Desantes, J.; Bermúdez, V.; Molina, S.; Linares Rodríguez, WG. (2011). Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions. Measurement Science and Technology. 22(11):1-14. doi:10.1088/0957-0233/22/11/115101S1142211Dobbins, R. A. (2007). Hydrocarbon Nanoparticles Formed in Flames and Diesel Engines. Aerosol Science and Technology, 41(5), 485-496. doi:10.1080/02786820701225820Davidson, C. I., Phalen, R. F., & Solomon, P. A. (2005). Airborne Particulate Matter and Human Health: A Review. Aerosol Science and Technology, 39(8), 737-749. doi:10.1080/02786820500191348McDonald, J. D., Barr, E. B., & White, R. K. (2004). Design, Characterization, and Evaluation of a Small-Scale Diesel Exhaust Exposure System. Aerosol Science and Technology, 38(1), 62-78. doi:10.1080/02786820490247623Brown, D. M., Wilson, M. R., MacNee, W., Stone, V., & Donaldson, K. (2001). Size-Dependent Proinflammatory Effects of Ultrafine Polystyrene Particles: A Role for Surface Area and Oxidative Stress in the Enhanced Activity of Ultrafines. Toxicology and Applied Pharmacology, 175(3), 191-199. doi:10.1006/taap.2001.9240Lighty, J. S., Veranth, J. M., & Sarofim, A. F. (2000). Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health. Journal of the Air & Waste Management Association, 50(9), 1565-1618. doi:10.1080/10473289.2000.10464197Kittelson, D. B. (1998). Engines and nanoparticles. Journal of Aerosol Science, 29(5-6), 575-588. doi:10.1016/s0021-8502(97)10037-4Dockery, D. W., Pope, C. A., Xu, X., Spengler, J. D., Ware, J. H., Fay, M. E., … Speizer, F. E. (1993). An Association between Air Pollution and Mortality in Six U.S. Cities. New England Journal of Medicine, 329(24), 1753-1759. doi:10.1056/nejm199312093292401Sem, G. J. (2002). Design and performance characteristics of three continuous-flow condensation particle counters: a summary. Atmospheric Research, 62(3-4), 267-294. doi:10.1016/s0169-8095(02)00014-5Ankilov, A., Baklanov, A., Colhoun, M., Enderle, K.-H., Gras, J., Julanov, Y., … Zagaynov, V. (2002). Intercomparison of number concentration measurements by various aerosol particle counters. Atmospheric Research, 62(3-4), 177-207. doi:10.1016/s0169-8095(02)00010-8Wiedensohlet, A., Orsini, D., Covert, D. S., Coffmann, D., Cantrell, W., Havlicek, M., … Litchy, M. (1997). Intercomparison Study of the Size-Dependent Counting Efficiency of 26 Condensation Particle Counters. Aerosol Science and Technology, 27(2), 224-242. doi:10.1080/02786829708965469Giechaskiel, B., Ntziachristos, L., & Samaras, Z. (2004). Calibration and modelling of ejector dilutors for automotive exhaust sampling. Measurement Science and Technology, 15(11), 2199-2206. doi:10.1088/0957-0233/15/11/004Cheng, M.-D., Storey, J. M., Wainman, T., & Dam, T. (2002). Impacts of venturi turbulent mixing on the size distributions of sodium chloride and dioctyl-phthalate aerosols. Journal of Aerosol Science, 33(3), 491-502. doi:10.1016/s0021-8502(01)00180-xHueglin, C., Scherrer, L., & Burtscher, H. (1997). An accurate, continuously adjustable dilution system (1:10 to 1:104) for submicron aerosols. Journal of Aerosol Science, 28(6), 1049-1055. doi:10.1016/s0021-8502(96)00485-5Lyyränen, J., Jokiniemi, J., Kauppinen, E. I., Backman, U., & Vesala, H. (2004). Comparison of Different Dilution Methods for Measuring Diesel Particle Emissions. Aerosol Science and Technology, 38(1), 12-23. doi:10.1080/02786820490247579Wong, C. P., Chan, T. L., & Leung, C. W. (2003). Characterisation of diesel exhaust particle number and size distributions using mini-dilution tunnel and ejector–diluter measurement techniques. Atmospheric Environment, 37(31), 4435-4446. doi:10.1016/s1352-2310(03)00571-5Liu, Z. G., Ford, D. C., Vasys, V. N., Chen, D.-R., & Johnson, T. R. (2007). Influence of Engine Operating Conditions on Diesel Particulate Matter Emissions in Relation to Transient and Steady-State Conditions. Environmental Science & Technology, 41(13), 4593-4599. doi:10.1021/es0616229Liu, Z. G., Vasys, V. N., & Kittelson, D. B. (2007). Nuclei-Mode Particulate Emissions and Their Response to Fuel Sulfur Content and Primary Dilution during Transient Operations of Old and Modern Diesel Engines. Environmental Science & Technology, 41(18), 6479-6483. doi:10.1021/es0629007Desantes, J. M., Bermúdez, V., Pastor, J. V., & Fuentes, E. (2004). Methodology for measuring exhaust aerosol size distributions from heavy duty diesel engines by means of a scanning mobility particle sizer. Measurement Science and Technology, 15(10), 2083-2098. doi:10.1088/0957-0233/15/10/019Lapuerta, M., Armas, O., & Gómez, A. (2003). Diesel Particle Size Distribution Estimation from Digital Image Analysis. Aerosol Science and Technology, 37(4), 369-381. doi:10.1080/02786820300970Wiedensohler, A. (1988). An approximation of the bipolar charge distribution for particles in the submicron size range. Journal of Aerosol Science, 19(3), 387-389. doi:10.1016/0021-8502(88)90278-9Wen, H. Y., Reischl, G. P., & Kasper, G. (1984). Bipolar diffusion charging of fibrous aerosol particles—II. charge and electrical mobility measurements on linear chain aggregates. Journal of Aerosol Science, 15(2), 103-122. doi:10.1016/0021-8502(84)90030-2Oh, H., Park, H., & Kim, S. (2004). Effects of Particle Shape on the Unipolar Diffusion Charging of Nonspherical Particles. Aerosol Science and Technology, 38(11), 1045-1053. doi:10.1080/027868290883324Matti Maricq, M. (2007). Chemical characterization of particulate emissions from diesel engines: A review. Journal of Aerosol Science, 38(11), 1079-1118. doi:10.1016/j.jaerosci.2007.08.001Katz, J. L. (1970). Condensation of a Supersaturated Vapor. I. The Homogeneous Nucleation of the n‐Alkanes. The Journal of Chemical Physics, 52(9), 4733-4748. doi:10.1063/1.1673706Burtscher, H. (2005). Physical characterization of particulate emissions from diesel engines: a review. Journal of Aerosol Science, 36(7), 896-932. doi:10.1016/j.jaerosci.2004.12.001Mamakos, A., Ntziachristos, L., & Samaras, Z. (2004). Comparability of particle emission measurements between vehicle testing laboratories: a long way to go. Measurement Science and Technology, 15(9), 1855-1866. doi:10.1088/0957-0233/15/9/02

Nivel de información médica sobre diabetes, actitud de los pacientes hacia la enfermedad y su asociación con el nivel de control glucémico

ObjetivoDeterminar el nivel de información y de actitud que sobre su enfermedad tienen pacientes con diabetes tipo 2 (DM2) y su asociación con el nivel de control glucémico.DiseñoEncuesta transversal survey.EmplazamientoDos unidades de medicina familiar.PacientesDoscientos sujetos con DM2.IntervencionesSe aplicaron 2 instrumentos validados para valorar nivel de conocimientos y actitud, y se midió el promedio de las últimas 6 glucemias.Mediciones y resultadosLa calificación global del instrumento de conocimientos fue 58,6 ± 17,9 (escala 0-100). Para el instrumento de actitud fue de 18,9 ± 2,1 (escala 0-35). La calificación de conocimientos del grupo controlado fue de 55,48 ± 16,8, y la del grupo descontrolado de 59,2 ± 18,1. La calificación sobre actitud del grupo controlado fue de 17,8 ± 2,3, y la del grupo descontrolado de 19,1 ± 2 (p = 0,001). El nivel de información proporcionado por el médico familiar fue del 42,9%, por el equipo de salud del 10,2% y por otras fuentes del 6,3%. En cuanto al análisis del grado de actitud y el nivel de información, hubo una mejor actitud cuando la información fue proporcionada por otras fuentes (p < 0,05). Por lo que respecta al porcentaje de información y el control glucémico, el nivel de control fue mejor cuando la información fue proporcionada por el equipo de salud (p < 0,01).ConclusionesEl nivel de información médica sobre diabetes proporcionada por el médico familiar y el equipo de salud es bajo, y sólo en este último caso se asocia a un mejor control glucémico. La actitud es mejor cuando se recibe información sobre diabetes de otras fuentes.ObjectiveTo determine the level of information and attitude that it has more than enough their illness has patient with diabetes type 2 (DM2), and their association with level of glucemic control.DesignCross-sectional.SettingTwo units of family medicine.Patient200 subject with DM2.InterventionsTwo instruments were applied validated to measure, level of knowledge and attitude was measured the average of the last 6 glucaemias.Measurements and resultsThe qualification average of the instrument of knowledge was 58.6 ± 17.9 (it scale 0–100). For the instrument of attitude it was of 18.9 ± 2.1 (it scale 0 at 35). The qualification of knowledge of the controlled group was of 55.48 ± 16.8, and of the uncontrolled group it was of 59.2 ± 18.1. The qualification has more than enough attitude of the controlled group it was of 17.8 ± 2.3, and of the uncontrolled group of 19.1 ± 2, p = 0.001. The proportionate level of information the family doctor was of 42.9%, of the team of health of 10.2% and of other sources of 6.3%. At the analysis of the degree of attitude and the level of information, there was a better attitude when the information was provided by other sources p < 0.05. In the percentage of information and the level of glucemic control, the control level was better when the information was for the team of health p < 0.01.ConclusionsThe level of medical information on diabetes provided by the family doctor and the team of health is low and it doesn't and only this last are associate to better glucemic control. The attitude is better when one receives information of other sources

The development of proliferative verrucous leukoplakia in oral lichen planus: a preliminary study

Background: Was to describe 14 cases of a proliferative verrucous leukoplakia as a clinical evolution of oral lichen planus. Material and Methods: The clinical and histopathological characteristics of 14 cases of OLP that progress towards a plaque-like and verrucous form were indicated, with monitoring over a period of six to 24.3 years. Results: The female/male ratio was 11/3, (78.6 and 21.4%). The mean age when the first biopsy was undertaken was 56.4 years old. None of the patients smoked during the study. As bilateral reticular was clinically diagnostic criterion, the second most frequent clinical form was the plaque form (n=10; 71.4%), followed by the atrophic (n=6; 42.8%), and erosive forms (n=4; 28.5%). Clinically it spread towards attached gingival mucosa and the hard palate. In the histopathologic study, there were a predominance of hyperkeratosis and verrucous epithelial hyperplasia. Three of the cases progressed to a squamous cell carcinoma, and one patient developed two verrucous carcinoma. Conclusions: Further research is needed to demonstrate if proliferative multifocal oral lichen planus and proliferative multifocal oral leukoplakia are the same disorder but have different behaviour of malignancy for reasons of origin

Arthrodiastasis for stiff hips in young patients

Joint distraction (arthrodiastasis) with a unilateral fixator was used to treat 9 patients with stiffness of the hip which had followed Perthes' disease (3), epiphysiolysis (2), congenital dysplasia (2), tuberculosis (1) and idiopathic chondrolysis (1). Their average age was 14 years, and they all had pain, limp and shortening of the leg. Distraction of 0.5 to 1 cm was maintained for an average of 94 days. The average range of movement subsequently was 65 degrees compared with 20 degrees before. The articular space was widened by an average of 2.8 mm, and only 3 patients had pain on follow up

Integration of genetic data on fisheries management models. The European hake case.

The European hake is one of the major commercially important species in Western Europe fisheries. Currently its management is divided into different functional units in the Mediterranean (GFCM, General Fisheries Commission for the Mediterranean) and two stocks in the Atlantic: the Southern and the Northern Stock. The basis for the definition of this management stock structure is under permanent discussion and in the latest years there were an increased amount of genetic studies addressing this topic. Integrated ecosystem assessment requires an improved understanding of the marine ecosystem to provide an effective advice. To this end we have gathered hake genetic information from different studies with the aim of developing a spatial assessment model that links the current stocks. These studies show a restricted gene flow between Southern hake and Mediterranean hake, although a smaller genetic distance between Southern and Northern stocks than one expected from two independent populations, suggesting the presence of a major gene flow from northern grounds core stock (Porcupine and Great Sole Banks) towards the Bay of Biscay and the northwest coast of the Iberian Peninsula. However the quantitative implementation of genetic metrics (such as Fst, migration rates, etc) into population dynamic models is not straightforward given the different nature and assumptions behind these different approaches. In this work we discuss the problems to link these different disciplines suggesting ways to overcome them. These include ways to improve future genetic sampling and developing plausible scenarios for genetic connectivity in population dynamic models

Portion control tableware differentially impacts eating behaviour in women with and without overweight

Portion control tableware has been described as a potentially effective approach for weight management, however the mechanisms by which these tools work remain unknown. We explored the processes by which a portion control (calibrated) plate with visual stimuli for starch, protein and vegetable amounts modulates food intake, satiety and meal eating behaviour. Sixty-five women (34 with overweight/obesity) participated in a counterbalanced cross-over trial in the laboratory, where they self-served and ate a hot meal including rice, meatballs and vegetables, once with a calibrated plate and once with a conventional (control) plate. A subsample of 31 women provided blood samples to measure the cephalic phase response to the meal. Effects of plate type were tested through linear mixed-effect models. Meal portion sizes (mean ± SD) were smaller for the calibrated compared with the control plate (served: 296 ± 69 vs 317 ± 78 g; consumed: 287 ± 71 vs 309 ± 79 g respectively), especially consumed rice (69 ± 24 vs 88 ± 30 g) (p < 0.05 for all comparisons). The calibrated plate significantly reduced bite size (3.4 ± 1.0 vs 3.7 ± 1.0 g; p < 0.01) in all women and eating rate (32.9 ± 9.5 vs 33.7 ± 9.2 g/min; p < 0.05), in lean women. Despite this, some women compensated for the reduced intake over the 8 h following the meal. Pancreatic polypeptide and ghrelin levels increased post-prandially with the calibrated plate but changes were not robust. Plate type had no influence on insulin, glucose levels, or memory for portion size. Meal size was reduced by a portion control plate with visual stimuli for appropriate amounts of starch, protein and vegetables, potentially because of the reduced self-served portion size and the resulting reduced bite size. Sustained effects may require the continued use of the plate for long-term impact

Influence of ball milling on CaO crystal growth during limestone and dolomite calcination: Effect on CO2 capture at Calcium Looping conditions

The multicycle CO2 capture performance of CaO derived from the calcination of ball-milled limestone and dolomite have been tested under high temperature and high CO2 concentration environment for the first time. Here it is shown that the CO2 capture capacity of CaO is inversely related to the milling power applied to the starting mineral and the size of nascent CaO nanocrystals. In situ X-ray diffraction analysis used to follow the average crystallite size of CaCO3 and CaO during the calcination process as a function of temperature demonstrates that crystal growth is notably enhanced in a CO2-rich atmosphere for milled sorbents. Contrary to early reports suggesting improved reactivity towards carbonation of CaO from milled sorbents, promoted agglomeration, and crystal growth under these more “realistic” conditions lead to a severe deterioration of both capture capacity and recyclability, as observed from the multicyclic carbonation/calcination experiments. Yet the negative effect of milling is less pronounced in dolomite due to the constrained sintering effect of the inert MgO grains that results in smaller CaO crystallite sizes, reduced crystal growth rate, and improved performance. These results provide insight on the role of CaO crystallinity on the carbonation reaction, useful for devising strategies to improve sorbents performance.Peer reviewe

Critical behavior of the frustrated antiferromagnetic six-state clock model on a triangular lattice

We study the anti-ferromagnetic six-state clock model with nearest neighbor interactions on a triangular lattice with extensive Monte-Carlo simulations. We find clear indications of two phase transitions at two different temperatures: Below $T_I$ a chirality order sets in and by a thorough finite size scaling analysis of the specific heat and the chirality correlation length we show that this transition is in the Ising universality class (with a non-vanishing chirality order parameter below $T_I$). At $T_{KT}(<T_I)$ the spin-spin correlation length as well as the spin susceptibility diverges according to a Kosterlitz-Thouless (KT) form and spin correlations decay algebraically below $T_{KT}$. We compare our results to recent x-ray diffraction experiments on the orientational ordering of CF$_3$Br monolayers physisorbed on graphite. We argue that the six-state clock model describes the universal feature of the phase transition in the experimental system and that the orientational ordering belongs to the KT universality class.Comment: 8 pages, 9 figure