abstract: The development of a Solid State Transformer (SST) that incorporates a DC-DC multiport converter to integrate both photovoltaic (PV) power generation and battery energy storage is presented in this dissertation. The DC-DC stage is based on a quad-active-bridge (QAB) converter which not only provides isolation for the load, but also for the PV and storage. The AC-DC stage is implemented with a pulse-width-modulated (PWM) single phase rectifier. A unified gyrator-based average model is developed for a general multi-active-bridge (MAB) converter controlled through phase-shift modulation (PSM). Expressions to determine the power rating of the MAB ports are also derived. The developed gyrator-based average model is applied to the QAB converter for faster simulations of the proposed SST during the control design process as well for deriving the state-space representation of the plant. Both linear quadratic regulator (LQR) and single-input-single-output (SISO) types of controllers are designed for the DC-DC stage. A novel technique that complements the SISO controller by taking into account the cross-coupling characteristics of the QAB converter is also presented herein. Cascaded SISO controllers are designed for the AC-DC stage. The QAB demanded power is calculated at the QAB controls and then fed into the rectifier controls in order to minimize the effect of the interaction between the two SST stages. The dynamic performance of the designed control loops based on the proposed control strategies are verified through extensive simulation of the SST average and switching models. The experimental results presented herein show that the transient responses for each control strategy match those from the simulations results thus validating them. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

O objetivo deste trabalho é investigar a relação entre a Temperatura da Superfície do Mar (TSM) no Oceano Atlântico Sul (OAS) e a precipitação no estado de São Paulo. Para tanto, adotaram-se as escalas mensal e sazonal. A técnica estatística multivariada, chamada Análise de Componentes Principais (ACP, ou EOF em inglês) foi aplicada para definir as áreas homogêneas do oceano (de \'A\' a \'L\') e as subregiões do continente (de 1 a 7). Além da definição das áreas e sub-regiões, a ACP identificou muito bem os padrões espaciais da precipitação e da TSM em todas as escalas adotadas: mensal contínua, mensal descontínua e sazonal. Na ACP da série temporal sazonal de verão, o primeiro e o segundo modos da precipitação evidenciam a distribuição espacial típica de verão (zonal) para o estado de São Paulo, e a variância explicada por esses dois modos juntos é de 59,79% do total. Esta distribuição espacial já havia sido observada nas análises iniciais a partir das médias sazonais da precipitação, padrão que se explica pelos fluxos de umidade que, nesta estação, devido ao sistema de monções da América do Sul, movem-se mais intensamente em direção ao continente. Já na ACP da série temporal sazonal de inverno, o primeiro e segundo modos da precipitação evidenciam a distribuição meridional, com variância explicada de 39,15 e 17,77%, respectivamente. Os sistemas frontais no inverno agem como responsáveis por uma parcela considerável do total precipitado, o que explica o padrão meridional da chuva. Os coeficientes de correlação linear significativos entre as áreas oceânicas e sub-regiões continentais homogêneas demonstraram que a variabilidade sazonal da precipitação está associada à TSM, sobretudo na porção central da área estudada (próximo ao litoral sul e sudeste do Brasil), nas estações seca (abril a setembro) e chuvosa (outubro a março). Além das variáveis principais (precipitação e TSM), os campos de Radiação de Onda Longa Emergente (ROLE), Pressão no nível do Mar (PNM), e Divergência do ar em 250 e 850hPa auxiliaram na identificação dos padrões atmosféricos e na análise dos eventos extremos. As estações consideradas atípicas, ou seja, as que apresentaram média muito acima ou muito abaixo do desvio padrão, foram separadas em quatro classes: verão chuvoso, verão seco, inverno chuvoso e inverno seco. A partir da análise desses eventos, conclui-se então que a TSM do OAS pode alterar consideravelmente o padrão sazonal de precipitação no estado de São Paulo, principalmente se estiver atrelada a padrões atmosféricos. No inverno, anomalias negativas (positivas) de TSM estão associadas com a precipitação acima (abaixo) da média climatológica nesse estado. Devido a bloqueios atmosféricos no OAS no verão, a diminuição da passagem de sistemas frontais pode intensificar anomalias positivas no oceano, as quais estão associadas aos períodos chuvosos no sul do país e de seca no estado de São Paulo. / The purpose of this paper is to study the relationship between the Sea Surface Temperature (SST) in the South Atlantic Ocean (SAO) and the precipitation in São Paulo state. So, the monthly and seasonal scales were adopted. The Principal Component Analysis multivariate statistic technic (PCA, and also called EOF) was applied to define the oceans homogeneous areas (from A to L) and the continents sub-regions (from 1 to 7). Besides defining the areas and sub-regions, the PCA has identified very well the spatial patterns of the precipitation and SST in all the adopted scales: continuous monthly, discontinuous monthly and seasonal. In the PCA of the summer seasonal temporal series, the first and the second precipitations mode evidence the summer-typical spatial distribution (zonal) for São Paulo state, and the variance explained by these two modes together is 59,79% of the total. This spatial distribution was already noted in the first analysis from the seasonal precipitation averages, and such a pattern is explained by the flow of humidity, which in the summer, owing to the South America monsoon systems, move more intensely toward the continent. On the other hand, in the PCA of the winter seasonal temporal series, the first and the second precipitations modes evidence the meridional distribution, with a variance explained from 39,15 to 17,77%, respectively. The frontal systems in the winter act as responsibles for a substantial portion of the total of precipitation, which explains the rains meridional pattern. The significative linear correlation coefficients between the oceanic areas and the homogeneous continental sub-regions demonstrate that the precipitations seasonal variability is associated to the SST, mostly in the central portion of the studied area (next to the southern and southeastern Brazilian coast), in the drought season (from April to September) and rainy season (from October to March). Besides the principal variables (precipitation and SST), the fields of Outgoing Long wave Radiation (OLR), Sea-level Pressure (SLP) and air Divergence in 250 and 850hPa has helped to identify the atmospheric patterns and to analyze the extreme events. The atypical seasons, in other words, those which presented an average too high or too low compared to the standard deviation, were divided in four categories: rainy summer, drought summer, rainy winter and drought winter. With the analysis of these events, it is possible to conclude that the SST of the SAO can change substantially the precipitation seasonal pattern in São Paulo state, mainly if it is linked to atmospheric patterns. In the winter, SSTs negative (positive) anomalies are associated to the overage (underage) climatologic precipitation in this state. Owing to atmospheric blockades on the SAO in the summer, the decreasing transit of frontal systems can intensify positive anomalies in the ocean, which are associated to the rainy periods in the Brazilian South and drought periods in the São Paulo state.

Durante o verão austral, diversas regiões do Brasil, como a Sudeste, porções das Regiões Sul e Nordeste e o Brasil central, sofrem períodos de intensa precipitação, geralmente associados à Zona de Convergência do Atlântico Sul (ZCAS), o que ocasiona sérios problemas econômicos e sociais nessas regiões. Assim, o objetivo geral deste trabalho foi estudar as principais características da ZCAS, sendo que, do ponto de vista de modelagem numérica, pretendeu-se estudar as influências da temperatura da superfície do mar (TSM) e da umidade do solo (US) principalmente na precipitação associada ao sistema. Esse estudo foi realizado através de simulações com o modelo regional BRAMS (Regional Atmospheric Modeling System with Brazilian Developments), para dois casos de ZCAS, ocorridos em 1998 e 1999, períodos, respectivamente, com TSMs do Pacífico leste e central anomalamente quentes (El Niño) e anomalamente frias (La Niña). Através de índices estatísticos foi verificado o desempenho do modelo, usando TSMs com resoluções espaciais e temporais diferentes, na previsão de precipitação nas regiões que compõem a ZCAS (oceânica, costeira e amazônica). O pior e o melhor desempenhos do modelo BRAMS se deram quando do uso de TSMs com resoluções espacial e temporal menos e mais refinadas, respectivamente, para o caso de ZCAS de 1998. Para o caso de 1999 não foram observadas diferenças significativas no desempenho do modelo. Grande parte do erro do modelo na previsão de chuva é devida ao viés do próprio modelo, que é melhor em identificar a ocorrência/não-ocorrência de chuva do que em localizar núcleos mais intensos. No entanto, o BRAMS apresenta alto skill no que se refere à quantidade de chuva. Com respeito à simulação de precipitação nas regiões que compõem a ZCAS, o melhor e o pior desempenhos do modelo se deram nas regiões amazônica e oceânica, respectivamente. Com relação à US verificaram-se as influências da condição de solo mais seca possível, aplicada às regiões de ZCAS continental, em características do sistema como convergência de umidade e precipitação. De maneira geral, a quantidade de precipitação acumulada nas regiões onde se aplicou a condição seca foi maior do que no experimento controle devido à convergência de umidade, que é transportada das regiões circunvizinhas para a região de solo mais seco por circulações de meso e grande escalas geradas por heterogeneidades na superfície. Analisaram-se ainda diferenças nas características da ZCAS observada e simulada em diferentes fases do El Niño-Oscilação Sul (ENOS). Os casos de ZCAS de 1998 e 1999 se apresentaram mais alongado sobre o Atlântico e predominantemente continental, respectivamente, o que confirma que períodos de El Niño (La Niña) favorecem a ocorrência de ZCAS oceânica (continental). Nos testes de sensibilidade do BRAMS à US foi observado provável efeito do ENOS sobre a ZCAS simulada, uma vez que o movimento ascendente na ZCAS amazônica foi menos intenso do que na costeira em 1998, ocorrendo o oposto em 1999. A fase quente (fria) do ENOS favorece a subsidência (ascendência) na região amazônica, podendo ter contribuído para enfraquecer (intensificar) o movimento vertical nessa região em 1998 (1999). / During austral summer, several regions of Brazil, as Southeast, portions of South and Northeast Regions and central Brazil, suffer periods of intense precipitation, generally associated with South Atlantic Convergence Zone (SACZ), which causes serious economic and social problems in those regions. Notwithstanding, the general objective of this work was to study the main features of SACZ, and in terms of numerical modeling, it intended to study the influences of the sea surface temperature (SST) and of the soil moisture (SM) mainly upon the precipitation associated with the system. This study was carried out through simulations with BRAMS (Regional Atmospheric Modeling System with Brazilian Developments) regional model, to two SACZ cases, occurred in 1998 and in 1999, periods, respectively, with SSTs of Eastern and central Pacific abnormally warm (El Niño) and abnormally cold (La Niña). Through statistical indices it was verified the model performance, using SSTs with different spatial and temporal resolutions, upon the precipitations forecasting in the regions that compound SACZ (oceanic, coastal and Amazon). The worst and the best performances of BRAMS model occurred when using SST\'s with less and more refined spatial and temporal resolutions, respectively, to the SACZ case of 1998. To the case of 1999 it was observed no significant differences in the models performance. Much of the models error in rains forecasting is due to the bias of the model itself, which is better in identifying the occurrence/non-occurrence of rain than in locate more intense nuclei. However, the BRAMS has high skill regarding to the amount of rain. About the precipitations simulation in the regions that compound SACZ, the best and the worst models performances occurred in the Amazon and oceanic regions, respectively. Concerning the SM it was verified the influences of the driest possible soil condition, applied to continental regions of SACZ, upon systems features such as moisture convergence and precipitation. In general, the amount of rainfall in regions where the dry condition was applied was higher than in the control experiment due to the moisture convergence, which is transported from surrounding regions to the one of drier soil by meso and large scale circulations generated by heterogeneities on the surface. It was also analyzed differences in the characteristics of observed and simulated SACZ at different phases of El Niño-Southern Oscillation (ENSO). The SACZ cases of 1998 and of 1999 were presented more elongated over the Atlantic and predominantly continental, respectively, confirming that periods of El Niño (La Niña) favor the occurrence of oceanic (continental) SACZ. In the BRAMS sensibility tests to SM it was observed probable effect of ENSO upon simulated SACZ, as the upward motion in Amazon SACZ was less intense than in the coastal one in 1998, occurring the opposite in 1999. The warm phase of ENSO favors the subsidence (rising) on Amazon region, which may have contributed to weaken (intensify) the vertical motion on the region in 1998 (1999).

Worldwide, coral cover has declined at rates that have often exceeded 5% per year since the 1980’s. Populations of scleractinians (stony corals) in the Florida Keys reef tract have declined as well, with some communities declining at rates > 3% per year. Decreased water quality (e.g., steady increases in the ocean water temperatures and increased pollution, nutrients, or water turbidity due to coastal runoff) are commonly attributed to this decline. But actual linkages between variability and trends in these environmental parameters, and in stony coral diversity and ecosystem functions such as net community production, have not yet been well characterized. With this research, I examined the influence of water quality (water temperature, nutrients and turbidity) on stony coral diversity and net community productivity in shallow-water reef ecosystems of the Florida Keys between 1996 and 2010. Differences in stony coral diversity in Florida Keys patch reefs with respect to sea surface temperature (SST) variability are evaluated in Chapter Two. Habitat-specific differences in stony coral diversity with respect to changes in a suite of environmental parameters (water turbidity, nutrients, water temperature and depth) are addressed in Chapter Three. Differences in daytime net community production and light-adapted stony coral photosynthetic efficiencies among three reef sites with different turbidity levels and seasons (May and October) are presented in Chapter Four. Environmental parameters examined to characterize the differences in stony coral diversity across the Florida Reef Tract included satellite-derived sea surface temperature [SST] and Degree Heating Weeks [DHWs], field observations of bio-optical properties of the water, and nutrient concentrations. These parameters were compared with live coral cover and species richness, net community production, and coral photo-physiological observations. In Chapter Two, I found that stony coral cover and diversity was higher in patch reefs of the Florida Keys relative to offshore and deeper reefs. Generally, patch reefs were characterized by intermediate to high SST variability (≥7.0°C2). Intermediate SST variance (7.0–10.9°C2) was correlated with higher diversity indices for patch reefs of the Upper (Shannon Diversity: 1.2–1.5) and Middle Keys (Species Richness: 13–19), suggesting that stony coral species in these habitats are either adapted to intermediate temperature ranges or thermal acclimation has taken place for individual colonies. Additionally, I found that found that years for which cold and warm-water extremes coincided (i.e., highest SST variance), such as 1997-98 and 2009-2010, led to significant reductions in both H’ and SR. Coral bleaching and mortality were associated with exposure to cold- and warm-water temperature extremes and the combination of both extremes were associated with reductions in stony coral diversity. The highest species richness and abundance were found in patch reefs of the Middle Keys, despite exposure to the warmest water-temperature anomaly events (as indicated by DHWs exceeding the coral bleaching threshold of 4) observed during the summers of 1998 and 2010. In Chapter Three, I found that the environmental parameters that best explained the differences in stony coral diversity (species composition and abundance) on patch reefs of the Florida Keys were water turbidity, nutrients, surface water temperature, % surface oxygen saturation and chlorophyll a concentrations averaged over a period of 24 months, along with depth (F = 4.4, R2 = 0.66, R2adj. = 0.40, p < 0.05). Surface water turbidity and depth were the most relevant environmental parameters driving the differences in stony coral diversity (R2 = 0.17, p < 0.05, R2 = 0.10, p < 0.05, respectively). The influence of these environmental parameters decreased towards offshore shallow and deep reefs. In the Florida Keys, stony coral diversity was the highest at patch reefs of the Middle and Lower Keys where exposed to higher water turbidity and nutrients than those in the Upper Keys located in clearer waters. This suggests that, at long-term scales, corals in patch reef environments exposed to higher water turbidity and water temperature variabilities (as reported in Chapter Two) might be better able to withstand thermal and light-induced stress. Moreover, a short-term study (described in Chapter Four) indicated that the net community production (NEP) was similar among sites with different water turbidity levels (i.e., Cheeca Rocks and Crocker Reef; Upper Keys and Sugarloaf Key; Lower Keys) and seasons (May or October). However, the light-adapted photosynthetic efficiencies (F/Fm’) varied spatiotemporally. The highest F/Fm’ values (0.57–0.69) were found at the nearshore patch reef of Sugarloaf Key, Lower Keys, in October 2012. At this patch reef, high light attenuation (Kd (488) = 0.12 m-1) was associated with absorption by colored dissolved organic matter and exacerbated by particulates following thunderstorms. The lowest F/Fm’ values ( This study represents a baseline against which future observations on coral reef biodiversity and net community production in the Florida Keys reef tract may be evaluated.

No description available.

Subseasonal variability of tropical Indian Ocean sea surface temperature is thought to influence the active-break cycle of the Asian monsoon. There are several open questions related to the role of surface fluxes, large-scale ocean circulation and subsurface ocean processes in the subseasonal variability of upper ocean temperature. We present a unified study of the subseasonal (2-90 day) variability of surface heat flux and upper ocean temperature and salinity throughout the tropical Indian Ocean in all seasons. We focus on the relation between surface fluxes and ocean response using a new satellitebased daily heat flux. The role of ocean processes (advection, entrainment and mixing) in determining SST variability is diagnosed from the daily satellite SST. Before the onset of the summer monsoon, sea surface temperature (SST) of the north Indian Ocean warms to 30-32oC. Climatological mean mixed layer depth in spring (March-May) is 10-20 m, and net surface heat flux (Qnet) is 80-100 Wm 2 into the ocean. It has been suggested that observed spring SST warming is small mainly due to (a) penetrative flux of solar radiation through the base of the mixed layer (Qpen), (b) advective cooling by upper ocean currents and (c) entrainment of sub-mixed layer cool water. We estimate the role of the first two processes in SST evolution from a two-week ARMEX experiment in April-May 2005 in the the southeastern Arabian Sea. The upper ocean is stratified by salinity and temperature, and mixed layer depth is shallow (6 to 12 m). Current speed at 2 m depth is high even under light winds. Currents within the mixed layer are quite distinct from those at 25 m. On subseasonal scales, SST warming is followed by rapid cooling. The cooling occurs although the ocean gains heat at the surface - Qnet is about 105 Wm 2 in the warming phase, and 25 Wm 2 in the cooling phase; penetrative loss Qpen, is 80 Wm 2 and 70 Wm 2. In the warming phase, SST rises mainly due to heat absorbed within the mixed layer, i.e. Qnet minus Qpen; Qpen, reduces the rate of SST warming by a factor of three. In the second phase, SST cools rapidly because (a) Qpen, is larger than Qnet, and (b) advective cooling is _85 Wm 2. A calculation using time-averaged heat fluxes and mixed layer depth suggests that diurnal variability of fluxes and upper ocean stratification tends to warm SST on subseasonal time scale. Buoy and satellite data suggest that a typical premonsoon intraseasonal SST cooling event occurs under clear skies and weak winds, when the ocean is gaining heat. In this respect, premonsoon SST cooling in the north Indian ocean is different from that due to MJO or monsoon ISO. As a follow-up to ARMEX, we use a short dataset from a field campaign in the premonsoon north Bay of Bengal to study diurnal variability of SST. In addition to the standard meteorological and hydrographic parameters measured from shipborne instruments and buoy sensors, we obtained a two-hourly record of subsurface sunlight profiles. Heat fluxes are seen to drive the SST warming during the day while both advection and entrainment/mixing are important during the night. The simple heat balance based on heat flux shows that it drives the diurnal cycle of SST, though ocean processes contribute towards night time cooling; this has been confirmed using the Price-Weller-Pinkel mixing model forced by heat flux and wind stress. A similar analysis for mixed layer salinity revealed that the salt balance in the region is dominated by advection rather than freshwater flux or entrainment/mixing. Buoy and satellite data show pronounced subseasonal oscillations of sea surface temperature (SST) in the summertime north Indian Ocean. The SST oscillations are forced mainly by surface heat flux associated with the active-break cycle of the south Asian summer monsoon. The input of freshwater (FW) from summer rain and rivers to the Bay is large, but not much is known about subseasonal salinity variability. We use 2002-2007 observations from Argo floats with 5-day repeat cycle to study the subseasonal response of temperature and salinity to surface heat and freshwater flux in the central Bay of Bengal and central Arabian Sea. Estimates of surface heat and freshwater flux are based on daily satellite data sampled along the float trajectory. We find that intraseasonal variability (ISV) of mixed layer temperature is mainly a response to net surface heat flux minus penetrative radiation during the summer monsoon season. In winter and spring, however, temperature variability appears to be mainly due to ocean processes rather than local heat flux. Variability of mixed layer freshwater content is generally independent of local surface flux (precipitation minus evaporation) in all seasons. There are occasions when intense monsoon rainfall leads to local freshening, but these are rare. The large subseasonal fluctuations observed in FW appear to be due to advection, suggesting that freshwater from rivers and rain moves in eddies or filaments. We have developed a new daily satellite-based heat flux dataset for the tropical Indian Ocean (30oE 120oE; 30oS 30oN); satellite data include surface air temperature and relative humidity from the Atmospheric Infrared Sounder (AIRS). On the seasonal scale (> 90 days) the flux compares reasonably well with climatologies and other daily data. On the subseasonal scale, our flux product has realistic behaviour relative to buoy data at validation sites. An important result is that ocean processes (advection, entrainment/detrainment, mixing at the base of the mixed layer) cool the tropical Indian Ocean SST by 8oC over the year. The largest contribution of ocean processes (_20oC SST cooling over the year) is in the western equatorial Indian Ocean. Ocean processes generally cool the upper ocean in all seasons and all regions, except in boreal winter, when they warm the north Indian Ocean. This is likely due to entrainment of warm sub-mixed layer water in regions of inversions. On subseasonal (2-90 days) scales, the contribution of air temperature and humidity to latent heat flux is roughly equal to the contribution from wind speed variability: Another interesting finding is that the contribution of air temperature and humidity increases away from the equator. One of the most important contributions of this thesis is the demonstration that tropical Indian Ocean SST has a coherent response to intraseasonal changes in heat flux associated with organised convection in the summer hemisphere. SST responds to flux in (i) the northeast Indian Ocean during May-October and (ii) the 15oS-5oN region during November-April. In the winter hemisphere and in regions with no organised convection, it is ocean processes and not fluxes which drive the subseasonal changes in SST. This result suggests that SST ISV feeds back to organise and sustain organised convection in the tropical atmosphere.

Den digitala och tekniska utvecklingen som har skett under 2010-talet har påverkat hela samhället. För företag och kunder har samhällsutvecklingen inneburit att roller förändrats och kunderna är allt mer involverade i skapandet av tjänster. På grund av tjänstens karaktärsdrag skapas osäkerhet i kundens förväntningar kring tjänsten, och tjänsteföretagens svårighet är att skapa en trygghet för kunden i servicemötet. Traditionellt sett har denna trygghet skapats av servicepersonal, men teknikutvecklingen har gjort att kunderna allt oftare interagerar med teknologi, Self Service Technology (SST), istället för personal. När teknologi introduceras förändras förutsättningarna för mötet och tidigare forskning kring servicemötet utmanas. Syftet med denna studie är att utveckla förståelse för om SSTs kan vara en relationsbyggande faktor mellan kund och företag. Vi vill identifiera vad som har betydelse för kundrelationen i ett tekniskt servicemöte, för att kunna ge praktiska råd till företag inom tjänstebranschen som står inför beslutet att implementera SSTs i sin verksamhet. För att undersöka detta har vi studerat restaurangbranschen. Vi har genomfört åtta kvalitativa intervjuer med kunder till en restaurang som använder sig av SST i ett fysiskt servicemöte. Den teoretiska bakgrunden om tjänster, relationer och det tekniska samt mellanmänskliga servicemötet har ställts i relation till materialet från intervjuerna. Därefter har vi kunnat besvara studiens problemformulering: Hur upplever kunden relationen till ett företag i en fysisk tjänstemiljö när interaktionen mellan parterna sker via SST? Resultatet av studien visar på att det är möjligt att upprätta en relation mellan kund och företag när interaktionen sker via SST. Hur kunden upplever relationen beror på hur kunden hanterar de nya förutsättningarna som det tekniska servicemötet innebär. Det tekniska servicemötet innebär nya roller och manus vilka kunden och företaget måste lära sig. Det är även viktigt att förstå att förväntningarna bildas av tidigare erfarenheter från såväl det tekniska servicemötet samt från det mellanmänskliga servicemötet för att god tjänstekvalitet ska kunna uppnås. Vi har också identifierat att den upplevda trygghetskänslan är avgörande för att en relation ska ha möjlighet att upprättas mellan kund och företag. För att SST ska vara relationsbyggande är det viktigt att tekniken kan bidra till kundens upplevda trygghetskänsla.

The bachelor thesis aims to explore whether students perceive the usage of self-service technology (SST) as positive, neutral or negative, which occurs before, under and after a visit at the library of University of Borås. In this paper, a qualitative user diary was used as a method to gather empirical data. An established UX method, customer journey mapping (CJM), was selected to analyze the empirical findings. The findings were further analyzed with a theoretical framework of the predecessor David Benyon to gain a deeper understanding of user experience in a cross-channel context. The study shows that students are overall positive to the usage of SST, but a deficiency of information affects the positive experience throughout the library.

No description available.

[ES] Las sequías han incrementado significativamente en las últimas décadas, y se espera que el cambio climático contribuya a esta tendencia creciente, lo que plantea mayores riesgos para aquellos sectores que dependen de la precipitación y los recursos hídricos. Por ello es necesario la detección temprana de la sequía para implementar estrategias y medidas de mitigación antes de que ocurra el evento. En esta investigación se caracterizan las sequías de la Demarcación Hidrográfica de Manabí (DHM) para entender el inicio, desarrollo y el fin del evento. Se realiza un análisis de las sequías para identificar el impacto económico que tiene el evento en la demarcación. Se ha desarrollado un sistema de predicción de sequía basado en Oscilación del Sur-El Niño (ENSO) e índices de sequías, y se han establecido medidas de gestión de sequías que permitan a los tomadores de decisiones prepararse al evento. La caracterización de las sequías en la demarcación, parte del análisis de las series históricas de precipitación y temperatura en el período octubre/1964 - septiembre/2012; para obtener la serie histórica de índices de sequía. Los índices aplicados son el Índice de Precipitación Estandarizado (SPI) y el Índice de Severidad de Sequía de Palmer (PDSI). Los resultados de los índices se validaron con los comunicados de prensa históricos disponibles en el Sistema de Inventario de Desastres. Los resultados indican que en la DHM las sequías son estacionales y anuales. En la Zona Norte y Centro el evento es de corta duración, y puede durar entre 3 y 9 meses y con frecuencia son incipientes y leves. En la Zona Sur, las sequías pueden durar más de un año, llegando a ser extremas. Para el desarrollo del sistema de predicción de sequías se correlacionó el Índice de Oscilación del Sur (SOI), el Índice de Niño Oceánico (ONI), la Temperatura de la Superficie del Mar (SST) en las regiones Niño 4.3, 3.4 y 1+2; y los índices de sequía aplicados, SPI y PDSI, para estimar la relación entre los eventos ENSO y la ocurrencia de sequía en la demarcación. El análisis de las correlaciones permite establecer un sistema de detección temprana de sequía basado en anomalías SST región Niño 1+2 (lag -7), SST región Niño 3 (lag -9) y SST región Niño 3.4 (lag -9) y en ambos índices de sequía. El sistema propuesto debe aplicarse en diciembre para detectar la sequía estacional y en mayo para detectar la sequía anual. Las medidas de mitigación de sequías se dividen en estratégicas, tácticas y de emergencia. Para establecer las etapas, los indicadores y los umbrales de la sequía, se toma como referencia los estándares internacionales y los Lineamientos publicados por la Comisión Nacional del Agua - México. / [CA] Les sequeres s'han incrementat significativament en les últimes dècades, i s'espera que el canvi climàtic contribueixi a aquesta tendència creixent, el que planteja més riscos per a aquells sectors que depenen de la precipitació i els recursos hídrics. Per això cal la detecció primerenca de la sequera per implementar estratègies i mesures de mitigació abans que passi l'esdeveniment. En aquesta investigació es caracteritzat les sequeres de la demarcació hidrogràfica de Manabí per entendre l'inici, desenvolupament i la fi de l'esdeveniment. S'ha realitzat una anàlisi de les sequeres per identificar l'impacte econòmic que té l'esdeveniment a la demarcació. Finalment s'ha desenvolupat un sistema de predicció de sequera basat en El Nen Oscil·lació de l'Sud (ENSO) i índexs de sequeres, i han establert mesures de gestió de sequeres que permetin als prenedors de decisions preparar-se a l'esdeveniment. La caracterització de les sequeres a la demarcació, part de l'anàlisi de les sèries històriques de precipitació i temperatura en el període octubre / 1964 - setembre / 2012; per obtenir la sèrie històrica d'índexs de sequera. Els índexs aplicats són l'Índex de Precipitació Estandarditzat (SPI) i l'Índex de Severitat de Sequera de Palmer (PDSI). Els resultats dels índexs es van validar amb els comunicats de premsa històrics disponibles en el Sistema d'Inventari de Desastres. Els resultats indiquen que a la DHM les sequeres són estacionals i anuals. A la Zona Nord i Centre l'esdeveniment és de curta durada, i pot durar entre 3 i 9 mesos i amb freqüència són incipients i lleus. A la Zona Sud, les sequeres poden durar més d'un any, arribant a ser extremes. Per al desenvolupament de sistema de predicció de sequeres es va correlacionar l'Índex de Oscil·lació de l'Sud (SOI), l'Índex de Nen Oceànic (ONI), la Temperatura de la Superfície de la Mar (SST) en les regions Nen 4.3, 3.4 i 1+2; i els índexs de sequera aplicats, SPI i PDSI, per estimar la relació entre els esdeveniments ENSO i l'ocurrència de sequera a la demarcació. L'anàlisi de les correlacions permet establir un sistema de detecció primerenca de sequera basat en anomalies SST regió Nen 1+2 (lag -7), SST regió Nen 3 (lag -9) i SST regió Nen 3.4 (lag -9) i en tots dos índexs de sequera. El sistema proposat s'ha d'aplicar al desembre per detectar la sequera estacional i al maig per detectar la sequera anual. Les mesures de mitigació de sequeres es divideixen en estratègiques, tàctiques i d'emergència. Per establir les etapes, els indicadors i els llindars de la sequera, es pren com a referència els específics internacionals i els Directrius publicats per la Comissió Nacional de l'Aigua - Mèxic. / [EN] Droughts have increased significantly in recent decades, and climate change is expected to contribute to this growing trend, which poses greater risks for those sectors that depend on precipitation and water resources. Therefore, early detection of drought is necessary to implement mitigation strategies and measures before the event occurs. In this research the droughts of Manabí River Basin District (MRBD) are characterized to understand the beginning, development and end of the event. An analysis of droughts is carried out to identify the economic impact that the event has on the River Basin District. A drought prediction system based on El Niño Southern Oscillation (ENSO) and drought indices has been developed, and drought management measures have been established that allow decision makers to prepare for the event. The characterization of droughts in the River Basin District, start of the analysis of the historical series of precipitation and temperature in the period October/1964 - September/2012 to obtain the historical series of drought indices. The indices applied are the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI). Index results were validated with the historical press releases available in the Disaster Inventory System. The results indicate that in the DHM the droughts are seasonal and annual. In the North and Central Zone the event is of short duration, and can last between 3 and 9 months and are often incipient and mild. In the South Zone, droughts can last more than a year, becoming extreme. For the development of the drought prediction system, the Southern Oscillation Index (SOI), the Ocean Niño Index (ONI), the Sea Surface Temperature (SST) in the Niño 4.3, 3.4 and 1+2 regions; and the applied drought indices, SPI and PDSI, were correlated to estimate the relationship between ENSO events and the occurrence of drought in the River Basin District. The correlation analysis allows establishing an early drought detection system based on anomalies SST Niño 1+2 region (lag -7), SST Niño 3 region (lag -9) and SST Niño 3.4 region (lag -9) and in both drought indices. The proposed system should be applied in December to detect seasonal drought and in May to detect annual drought. Drought mitigation measures are divided into strategic, tactical and emergency. In order to establish the stages, the indicators and the thresholds of the drought, the international specific ones and the Guidelines published by the National Water Commission - Mexico are taken as reference. / A la Secretaría de Educación Superior, Ciencia, Tecnología e Innovación del Ecuador (SENESCYT) por financiar esta investigación en el programa de becas: "Convocatoria Abierta 2012, Segunda Fase" (contrato 323 -2012). / Zambrano Mera, YE. (2020). Determinación de medidas de gestión de sequías en climas tropicales. Aplicación a la Demarcación Hidrográfica de Manabí - Ecuador [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149400 / TESIS