7,313 research outputs found
Modelagem da partida de máquinas síncronas de pólos salientes maciços
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.O objetivo deste trabalho é modelar a partida das máquinas síncronas de pólos salientes maciços (MSPSM) a fim de calcular o torque, a corrente e o aquecimento gerado nas sapatas polares. A metodologia desenvolvida está baseada na determinação dos parâmetros de eixo direto (d) e de quadratura (q) a partir de simulações de ensaios em freqüência da máquina com rotor travado. As simulações dos ensaios são realizadas utilizando o método de elementos finitos (programa EFCAD) e os resultados são modelados por curvas de tendência. De posse das equações das indutâncias de eixo direto e de quadratura e utilizando-se equações em regime quase permanente da máquina síncrona, calculam-se o torque eletromagnético médio, a envoltória da parte oscilante do torque eletromagnético (torque oscilante) e a corrente eficaz do estator em função da velocidade. Com a corrente do estator, calculam-se as perdas por pólo no rotor também através de elementos finitos (EFCAD). Todo o processo de simulação é realizado através de um programa composto por diversos módulos computacionais encadeados apropriadamente para facilitar a utilização por parte do usuário
D. Katsonopoulou and E. Partida (eds), ΦΙΛΕΛΛΗΝ. Essays presented to Stephen G. Miller (The Helike Society, Athens 2016)
No full textBook Review "D. Katsonopoulou and E. Partida (eds), ΦΙΛΕΛΛΗΝ. Essays presented to Stephen G. Miller (The Helike Society, Athens 2016)
Some reflections on the orientations and volume of accounting history research in the 21st century.
No full textEste artículo toma como punto de partida el 8th World Congress of Accounting Historians e intenta identificar las orientaciones que la investigación en historia de la contabilidad ha seguido desde entonces, es decir, desde el año 2000 hasta el 2007, los primeros años del siglo XX. El principal propósito de este ensayo es averiguar si ha habido novedades significativas en las direcciones de la investigación o, si por el contrario, su desarrollo ha seguido el curso previsible. Trataremos de asociar este propósito al estudio del volumen de la investigación publicada a este respecto en las principales revistas de contabilidad. Después de haber examinado y descrito la evolución de la historia de la contabilidad en estos primeros años del presente siglo, presentaremos algunas consideraciones personales acerca de los derroteros en que la investigación podría moverse en el próximo futuro. Taking as starting point the 8th World Congress of Accounting Historians this paper attempts to identify the orientations followed by accounting history research in the first years of the 21st century, that is, from 2000 up to 2007. The main purpose of the attempt is to find out whether there have been significant novelties in the directions of research or, on the contrary, its development has run in the foreseeable course. We shall try to associate this purpose to the study of the amount of related research published in the main accounting journals. After having examined and described the developments of accounting history research in the first years of present century, the paper presents some considerations on the directions in which research should move in the next future.Historia de la contabilidad, investigación, tendencias, siglo XXI. Accounting History, research, orientations, 21st century.
Adoption and diffusion of double entry book-keeping in Mexico and Spain: A related but under-investigated development
No full textThere is a consensus within Mexican accounting historiography regarding widespread use of double entry bookkeeping by the end of the 19th Century in the realm of both private and public enterprise. However, there is conflicting and even contradictory claims as to when exactly this technique arrived to the viceroyalty of New Spain (present day Mexico) as well as its diffusion during the colonial era. In this article we address this conflict while putting forward the idea that the history of ‘modern’ accounting practice in Latin America should be framed by developments in its former colonial power. We offer the analysis of primary and secondary source material to support the view that there was continuity in the use of double entry in Spain and therefore, the so called ‘period of silence and apparent oblivion’ seems limited to the production of indigenous accounting thought (as expressed in the production of bibliographic material such as manuals and textbooks). We conclude that the history of Latin America accounting should be wary of extrapolating everyday practice by interpreting bibliographic material and proceed by examining surviving company documents as well as informal educational practices amongst organisations based in the metropolis and its then colonies.double entry, diffusion of accounting systems, knowledge transfer, Mexico (New Spain), Spain
Piecemeal trade reform in partially liberalized economies : an evaluation for Turkey
No full textTurkey undertook a major liberalization of trade policy in the 1980s. Import quotas disappeared, the Turkish lira was made convertible, and tariffs are generally lower. Those changes and the export subsidies that remain have removed the anti-export bias from Turkey's external incentive regime. Using a 40-sector computable general equilibrium model, the authors consider several more trade liberalization options available to the Turkish government. They conclude that uniformity of tariffs and export subsidies would substantially improve Turkey's welfare. Although the"Ramsey"optimal import taxation would call for non-uniform import taxes inversely proportional to the elasticity of import demand in each sector, the observed dispersion of tariff structure in Turkey is inconsistent with optimal departures from uniform protection. In fact, uniformity achieves an extremely high proportion of the benefits of full trade liberalization because, in the absence of a general anti-export bias, theprincipal distortion remaining in the trade regime derives from dispersion of the tariff and, especially the export subsidy structure. An increasing number of developing countries - including Chile, Indonesia, Mexico, and Poland - have in recent years undertaken extensive trade liberalization. It is no longer clear that these economies retain an anti-export bias in their trade regime. Perhaps the most important policy conclusion the authors reach is that one must be wary of advocating piecemeal reform of tariffs or export subsidies alone. Piecemeal across-the-board tariff reductions do not always improve welfare; they must generally be coordinated with reductions in export subsidies to ensure improved welfare. The authors counterfactually assume that Turkey's tariffs are at the 1985 level which reintroduces an anti-export bias of import tariffs. In this case, piecemeal tariff reduction to the 1989 level is beneficial. Even small export subsidies are not always beneficial, despite the rule of thumb that small export subsidies are a welfare-enhancing offset to the anti-export bias of import tariffs. Export subsidies in Turkey are highly dispersed, and piecemeal reductions in the export subsidies reduce that dispersion. When the authors counterfactually impose uniformity of tariffs and export subsidies, they note that small export subsidies are beneficial as a piecemeal policy for offsetting the anti-export bias. Policymakers in developing countries have occasionally applied export subsidies in individual sectors with high tariffs as a means of encouraging exports in a sector that may otherwise rely on the highly protected domestic market. The authors show that in Turkey high export subsidies in sectors with high tariffs are particularly counterproductive - because at the multisector level the distortion introduced by the export subsidy dominates the reduction in anti-export bias. Turkey's proposed policy of harmonizing its tariff to the European Community's (EC's) common external tariff would yield only small welfare changes. Harmonizing the EC tariffs will require lowering tariffs below already low levels, in the presence of export subsidies almost as large as the existing average effective tariff rate. However harmonizing to the EC tariff structure can be beneficial if at the same time export subsidies are removed or reduced.Environmental Economics&Policies,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Tax Law,Trade Policy
A dopamine- and protein kinase A-dependent mechanism for network adaptation in retinal ganglion cells
No full textVertebrates can detect light intensity changes in vastly different photic environments, in part, because postreceptoral neurons undergo "network adaptation." Previous data implicated dopaminergic, cAMP-dependent inhibition of retinal ganglion cells in this process yet left unclear how this occurs and whether this occurs in darkness versus light. To test for light- and dopamine-dependent changes in ganglion cell cAMP levels in situ, we immunostained dark- and light-adapted retinas with anti-cAMP antisera in the presence and absence of various dopamine receptor ligands. To test for direct effects of dopamine receptor ligands and membrane-permeable protein kinase ligands on ganglion cell excitability, we recorded spikes from isolated ganglion cells in perforated-patch whole-cell mode before and during application of these agents by microperfusion. Our immunostainings show that light, endogenous dopamine, and exogenous dopamine elevate ganglion cell cAMP levels in situ by activating D1-type dopamine receptors. Our spike recordings show that D1-type agonists and 8-bromo cAMP reduce spike frequency and curtail sustained spike firing and that these effects entail protein kinase A activation. These effects resemble those of background light on ganglion cell responses to light flashes. Network adaptation could thus be produced, to some extent, by dopaminergic modulation of ganglion cell spike generation, a mechanism distinct from modulation of transmitter release onto ganglion cells or of transmitter-gated currents in ganglion cells. Combining these observations with results obtained in studies of photoreceptor, bipolar, and horizontal cells indicates that all three layers of neurons in the retina are equipped with mechanisms for adaptation to ambient light intensity
Frontal subduction of the Mid-Atlantic Bight shelf water at the onshore edge of a warm-core ring
No full textAuthor Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans, 123(11), (2018): 7795-7818. doi: 10.1029/2018JC013794.This work studies the subduction of the shelf water along the onshore edge of a warm‐core ring that impinges on the edge of the Mid‐Atlantic Bight continental shelf. The dynamical analysis is based on observations by satellites and from the Ocean Observatories Initiative Pioneer Array observatory as well as idealized numerical model simulations. They together show that frontogenesis‐induced submesoscale frontal subduction with order‐one Rossby and Froude numbers occurs on the onshore edge of the ring. The subduction flow results from the onshore migration of the warm‐core ring that intensifies the density front on the interface of the ring and shelf waters. The subduction is a part of the cross‐front secondary circulation trying to relax the intensifying density front. The dramatically different physical and biogeochemical properties of the ring and shelf waters provide a great opportunity to visualize the subduction phenomenon. Entrained by the ring‐edge current, the subducted shelf water is subsequently transported offshore below a surface layer of ring water and alongside of the surface‐visible shelf‐water streamer. It explains the historical observations of isolated subsurface packets of shelf water along the ring periphery in the slope sea. Model‐based estimate suggests that this type of subduction‐associated subsurface cross‐shelfbreak transport of the shelf water could be substantial relative to other major forms of shelfbreak water exchange. This study also proposes that outward spreading of the ring‐edge front by the frontal subduction may facilitate entrainment of the shelf water by the ring‐edge current and enhances the shelf‐water streamer transport at the shelf edge.W. G. Z. was supported by the National Science Foundation under grants OCE‐1657853, OCE‐1657803, and OCE 1634965. JP is grateful for the support of the Woods Hole Oceanographic Institution Summer Student Fellow Program in 2016 and 2017. W. G. Z. thanks Kenneth Brink, Glen Gawarkiewicz, Rocky Geyer, Steven Lentz, Dennis McGillicuddy, Robert Todd, and John Trowbridge for helpful discussions during the course of the study or useful comments on earlier versions of the manuscript. The satellite sea surface temperature data were obtained from the University of Delaware Ocean Exploration, Remote Sensing, Biogeography Lab (led by Matthew Oliver), through the Mid‐Atlantic Coastal Ocean Observing System (MARACOOS) data server (http://tds.maracoos.org/thredds/catalog.html). The OOI Pioneer Array mooring and glider data presented in this paper were downloaded from the National Science Foundation OOI data portal (http://ooinet.oceanobservatories.org) in July–August 2016.2019-04-1
Avaliação técnico-econômica de alternativas de lodos ativados no tratamento de esgotos domésticos
No full textTCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Sanitária e Ambiental.O tratamento de esgotos no Brasil situa-se num cenário de grandes desafios, sendo o sistema de Lodos Ativados uma importante tecnologia, largamente utilizada e com elevada eficiência de tratamento. Este estudo tem como objetivo avaliar os custos e benefícios de três sistemas de tratamento de esgotos, por variantes da tecnologia de lodos ativados, dimensionados para atender uma população de 100.000 habitantes. É estabelecido um cenário de mesmos parâmetros ambientais para as alternativas consideradas, com as seguintes premissas: (i) necessidade de 90% de eficiência na remoção de carga orgânica (DQO); (ii) necessidade de nitrificação (80%) e (iii) desnitrificação (60%); (iv) estabilização do lodo por processos aeróbios ou anaeróbios.Para estabelecer a comparação entre as alternativas, é aplicada a metodologia de custo do ciclo de vida. Esta metodologia se traduz num método de cálculo da totalidade dos custos inerentes ao projeto, durante toda a vida do mesmo. Os custos e benefícios associados aos respectivos sistemas de tratamento de esgotos são identificados e classificados. Os custos refletem todas as despesas do projeto em questão, desde as primeiras despesas até o fim da vida útil do projeto, e são classificados como custos de investimento inicial, e custos de OM&R (operação, manutenção e reparação). Com o objetivo de simplificar o estudo, o custo de desidratação do lodo não será considerado, apenas será considerado o custo para disposição de lodo em aterro sanitário. Os custos das alternativas avaliadas relevam principalmente os seguintes aspectos: área construída, custos de implantação de obras civis e aquisição de equipamentos, consumo de energia, custo de disposição de lodo, potencial de aproveitamento energético do biogás
Luz y dopamina modulan la excitabilidad ad de las celulas ganglionares de retina de carpa dorada
No full textLa luz y la dopamina endégena de la retina producen un aumento de cAMP en las
celula ganglionares de retina intacta de cara dorada. A la vista de esto
resultados analizamos el efecto de la dopamine y de alguno de sus agonistas, asi
como del cAMP, en ia excitabilidad de estas células. Utilizando luz infrarroja se
aislaron enzimaticamente las células ganglionares de retinas de carpas adaptadas
a la oscuridad. Mediante la teenica de patch-cIamp se registraron los potenciales
de accion de células ganglionares en conifguracion whole-cellperforated-patch.
Se observe que SKFBS393 (agomista de los receptores dopaminérgicos de tipo
D1), dopamina y 8-Br-cAMP aumentan el umbral de descarga de pcteneiales de
accidn, reducen la frecuencia (y el numere de poteneiales de accidn) para un
determinado estimulo de corriente, y aumentan el tiempo necesario para que se
descargue el potertcial de accidn en estas células. SCH23390 (antagcmista de los
reeeptores D1) es capaz de revertir estos efectcs. La activacién de l0s receptores
dopaminérgiccs de tipo D1 reduce la excitabilidad de las células ganglicnanes de
carpa dorada. Este efecto parece estar mediado por la activacidn de la proteina
quinasaA que aumenta 10s niveles citoplasmaticos de cAMP, ya que la aplicacién
de un inhibidor de esta quinasa es capaz de revertir el efecto de SKF38393 sobre
estas celulas. Estes resultados estém de acuerdo com la obsewacién de que el
aumento de la liberacién de dopamina en la retina por efecto de la luz reduce la
sensibilidad para el contraste luminico en estas células
Carta en favor del gobernador interino de las Californias, Pedro Fages, en su partida de Monterrey, 1774 julio 19
No full textFr. Junípero Serra informa sobre la partida del oficial Don Pedro Fages, quien está dejando el presidio y se dirige hacia San Diego. Niega cualquier antagonismo personal hacia el oficial; se sintió obligado a informar sobre la conducta antagonista de Fages hacia los frailes en el pasado, creyendo que era necesario para la prosperidad de la región. Reconoce la posibilidad de inexactitudes en los informes debido a información de segunda mano y expresa el deseo de que se trate a Fages con piedad y misericordia. El autor humildemente menciona sus propias contribuciones a la conquista de la región de California y se ofrece a renunciar a cualquier crédito o reconocimiento que pueda haber recibido en favor del oficial. —— Fr. Junípero Serra reports on the departure of acting governor of the Californias, Don Pedro Fages, who is leaving the presidio and heading towards San Diego. He disclaims any personal antagonism towards the officer; he had felt obligated to report on Fages' antagonistic conduct against the friars in the past, believing it was necessary for the prosperity of the region. He acknowledges the possibility of inaccuracies in the reports due to second-hand information and expresses a desire for Fages to be treated with kindness and mercy. The author humbly mentions their own contributions to the conquest of the California region and offers to surrender any credit or recognition they may have received in favor of the officer. 2 f. (4 p.
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