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Estimation of Daily Actual Evapotranspiration using Microwave and Optical Vegetation Indices for Clear and Cloudy Sky ConditionsRangaswamy, Shwetha Hassan January 2017 (has links) (PDF)
Evapotranspiration (ET) is a significant hydrological process. It can be studied and estimated using remote sensing based methods at multiple spatial and temporal scales. Most commonly and widely used remote sensing based methods to estimate actual evapotranspiration (AET) are a) methods based on energy balance equations, b) vegetation coefficient based method and c) contextual methods. These three methods require reflectance and land surface temperature (LST) data measured at optical and thermal portion of the electromagnetic spectrum. However, these data are available only for clear sky conditions and fail to be retrieved under overcast conditions creating gaps in the data, which result in discontinuous of AET product. Moreover, energy balance equation based methods and evaporative fraction (EF) based contextual methods are difficult to apply over overcast conditions. In this context, vegetation coefficient based (Tasumi et al., 2005; Allen et al., 2005) and microwave remote sensing based methods can be applied under cloudy sky conditions (Sun et al., 2012), since microwave radiations can penetrate through clouds, but these data are available at coarse resolution. In the vegetation coefficient method temporal upscaling can be avoided. Therefore in this research vegetation coefficient based method is employed over Cauvery basin to estimate daily AET for clear and cloudy sky conditions. Required critical variables for this method such as reference evapotranspiration (ETo) and vegetation coefficients are obtained using LST and optical vegetation indices for all sky conditions. In this study, all sky conditions refer to both clear and cloudy sky conditions.
Most important variable for estimation of ETo using radiation and temperature based models is air temperature (Ta). In this study, for better accuracy of Ta, two satellite based approaches namely, Temperature Vegetation Index (TVX) and Advance Statistical
Approaches (ASA) were evaluated. In the TVX approach, in addition to traditional Normalized Difference Vegetation Index (NDVI), other vegetation indices such as Enhanced Vegetation Index (EVI) and Global Vegetation Moisture Index (GVMI) were also examined. In case of ASA, bootstrap technique was used to generate calibration and validation samples and Levenberg Marquardt algorithm was used to find the solution of the models. The better of the Ta results obtained out of these two approaches were employed in the ETo models and are referred as Ta based ETo models. Instead of Ta, processed LST data obtained directly from the satellite (Aqua/Moderate Resolution Imaging Spectroradiometer (MODIS)) was applied in the ETo models and these are referred as LST based ETo models. These Ta and LST based Hargreaves-Samani (H-S), Makkink (Makk) and Penman Monteith Temperature (PMT) models were evaluated by comparing with the FAO56 PM model. Additionally, simple LST based equation (SLBE) proposed by Rivas et al. (2004) was also examined. Required solar radiation (Rs) data for ETo estimation was obtained from Kalpana1/VHRR satellite data. Results implied that, Ta based PMT model performed better than the Ta based H-S, Makk and SLBE with less RMSE, MAPE and MBE values for all land cover classes and for various climatic regions for clear sky conditions. LST based H-S, PMT, Makk and Ta based Makkink advection models predominantly overestimated ETo for the study region. In the case of TVX approach, to estimate maximum Ta (Tmax), GVMI performed better than NDVI and EVI. Nevertheless, TVX approach poorly estimated Tmax in comparison with statistical approach. ASA performed better for both Tmax and minimum Ta. This study demonstrates the applicability of satellite based Ta and ETo models by considering very few variables for clear sky conditions.
Spatially distributed vegetation coefficients (Kv) data with high temporal resolution is another important variable in vegetation coefficient method for daily AET estimation and also it is in demand for crop condition assessment, irrigation scheduling, etc. But available Kv models application hinders because of two main reasons i.e 1) Spectral reflectance based Kv accounts only for transpiration factor but not evaporation, which fails to account for total AET. 2) Required optical spectral reflectances are available only during clear sky conditions, which creates gaps in the Kv data. Hence there is a necessity of a model which accounts for both transpiration and evaporation factors and also gap filling method, which produces accurate continuous quantification of Kv values. Therefore, different combinations of EVI, GVMI and temperature vegetation dryness index (TVDI) have been employed in linear and non linear regression techniques to obtain best model. This best Kv model had been compared with Guershman et al. (2009) Kv model. To fill the gaps in the data, initially, temporal fitting of Kv values have been examined using Savitsky-Goley (SG) filter for three years of data (2012 to 2014), but this fails when sufficient high quality Kv values were unavailable. In this regard, three gap filling techniques namely regression, Artificial Neural Networks (ANNs) and interpolation techniques have been analyzed. Microwave polarization difference index (MPDI) has been employed in ANN technique to estimate Kv values under cloudy sky conditions. The results revealed that the combination of GVMI and TVDI using linear regression technique performed better than other combinations and also yielded better results than Guershman et al. (2009) Kv model. Furthermore, the results indicated that SG filter can be used for temporal fitting and for filling the gaps, regression technique can be used as it performed better than other techniques for Berambadi station.
Land Surface Temperature (LST) with high spatiotemporal resolution is required in the estimation of ETo to obtain AET. MODIS is one of the most commonly used sensors owing to its high spatial and temporal availability over the globe, but is incapable of providing LST data under cloudy conditions, resulting in gaps in the data. In contrast, microwave measurements have a capability to penetrate under clouds. The current study proposes a methodology by exploring this property to predict high spatiotemporal resolution LST under cloudy conditions during daytime and night time without employing in-situ LST measurements. To achieve this, ANN based models were employed for different land cover classes, utilizing MPDI at finer resolution with ancillary data. MPDI was derived using resampled (from 0.250 to 1 km) brightness temperatures (Tb) at 36.5 GHz channel of dual polarization from Advance Microwave Scanning Radiometer (AMSR)-Earth Observing System and AMSR2 sensors. The proposed methodology was quantitatively evaluated through three performance measures namely correlation coefficient (r), Nash Sutcliffe Efficiency (NSE) and Root Mean Square Error (RMSE). Results revealed that during daytime, AMSR-E(AMSR2) derived LST under clear sky conditions corresponds well with MODIS LST resulting in values of r ranging from 0.76(0.78) to 0.90(0.96), RMSE from 1.76(1.86) K to 4.34(4.00) K and NSE from
0.58(0.61) to 0.81(0.90) for different land cover classes. For night time, r values ranged from 0.76(0.56) to 0.87(0.90), RMSE from 1.71(1.70) K to 2.43(2.12) K and NSE from 0.43 (0.28) to 0.80(0.81) for different land cover classes. RMSE values found between predicted LST and MODIS LST during daytime under clear sky conditions were within acceptable limits. Under cloudy conditions, results of microwave derived LST were evaluated with Ta which indicated that the approach performed well with RMSE values lesser than the results obtained under clear sky conditions for land cover classes for both day and nighttimes. These predicted LSTs can be applied for the estimation of soil
moisture in hydrological studies, in climate studies, ecology, urban climate and environmental studies, etc.
AET was estimated for all sky conditions using vegetation coefficient method. Essential parameter ETo under cloudy conditions was estimated using LST and Ta based PMT and H-S models and required solar radiation (Rs) in these two models estimated using equation proposed by Samani (2000). In this equation it was found that the differences between LSTmax or Tmax and LSTmin or Tmin could able to capture the variations due to cloudy sky conditions and hence can be used for estimating ETo under cloudy sky conditions. Results revealed that the estimated Rs correlated well with observed Rs for Berambadi station under cloudy conditions for the year 2013. PMT based ETo values were corresponded with observed ETo under cloudy sky condition. The difference between LST and Ta was less during cloudy conditions, therefore LST or Ta can be used as the only input in temperature based PMT model to estimate ETo. AET estimated correlated well with the observed AET values for clear and cloudy sky conditions. In addition, AET estimated using vegetation coefficient method was compared with two source energy balance (TSEB) method developed by Nishida et al. (2003) under clear sky conditions. It was found that the improved vegetation coefficient method performed better than the TSEB method for Berambadi station.
Other microwave vegetation indices such as Microwave Vegetation Indices (MVIs) and Emissivity Difference Vegetation Index (EDVI) are available in literature. Therefore in this study, MVIs are used to predict LST under cloudy conditions using proposed methodology to check whether the MVIs could yield better LST values. Results showed that MPDI performed better than MVIs to predict LST under cloudy sky conditions. Furthermore, MPDI obtained using dual polarizations of 37 GHz channel Tb has advantage
of having fine spatial resolution compared to MVIs, as it requires Tb of 19 GHz in addition to Tb of 37 GHz channel which is of coarse resolution and therefore uncertainties resulting from re-sampling technique can be minimized.
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Developing process quality measurement in shipbuilding industryBasic, Selma January 2019 (has links)
This thesis investigates the possibility to adapt Overall Equipment Effectiveness (OEE), tothe development process in the shipbuilding industry.More specifically the development process wasdelimited to the phases; design, work preparation, production and verification.Ordinarily, OEE is a performance measurement for mass production. Itincludes aquality parameter which has been the focus of this thesis. Both literature review and case study investigation show that process quality is of critical importance in the shipbuilding industry because of the needs for dimensional accuracy and high-quality assemblage.The three main factors affecting process quality are;the flow of information between engineering phaseand productionphase, and the amount of rework and delays. The factors wereevaluated along an optimization method with a specific attention to process quality. Acase studywas conductedto confirm the relevance of the literature review on factors affecting process qualityand allowedto gather factors in process quality that are relevant to the industry.In light of those results, I re-developed a model providingnew measurement of what I call OPQE (Overall Process Quality Efficiency).This study contributes to a betterunderstanding of process quality in ETO(Engineering-To-Order)industries. Notably it shows how deviations that require rework and causesdelays are impacting process quality. It also shows that detecting errors early in the process of production is essential for insuring quality control. An error detected late affects negatively process quality and increases cost.
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Electrical, Magnetic, Thermal Modeling and Analysis of a 5000A Solid-State Switch Module and Its Application as a DC Circuit BreakerZhou, Xigen 28 September 2005 (has links)
This dissertation presents a systematic design and demonstration of a novel solid-state DC circuit breaker.
The mechanical circuit breaker is widely used in power systems to protect industrial equipment during fault or abnormal conditions. Compared with the slow and high-maintenance mechanical circuit breaker, the solid-state circuit breaker is capable of high-speed interruption of high currents without generating an arc, hence it is maintenance-free. Both the switch and the tripping unit are solid-state, which meet the requirements of precise protection and high reliability. The major challenge in developing and adopting a solid-state circuit breaker has been the lack of power semiconductor switches that have adequate current-carrying capability and interruption capability.
The high-speed, high-current solid-state DC circuit breaker proposed and demonstrated here uses a newly-emerging power semiconductor switch, the emitter turn-off (ETO) thyristor as the main interruption switch. In order to meet the requirement of being a high-current circuit breaker, ETO parallel operation is needed. Therefore the major effort of this dissertation is dedicated to the development of a high-current (5000A) DC switch module that utilizes multiple ETOs in parallel. This work can also be used to develop an AC switch module by changing the asymmetrical ETOs used to symmetrical ETOs.
An accurate device model of the ETO is needed for the development of the high-current DC switch module. In this dissertation a novel physics-base lumped charge model is developed for the ETO thyristor for the first time. This model is verified experimentally and used for the research and development of the emitter turn-off (ETO) thyristor as well as the DC switch module discussed in this dissertation.
With the aid of the developed device model, the device current sharing between paralleled multiple ETO thyristors is investigated. Current sharing is difficult to achieve for a thyristor-type device due to the large device parameter variations and strong positive feedback mechanism in a latched thyristor. The author proposes the "DirectETO" concept that directly benefits from the high-speed capability of the ETO and strong thermal couplings among ETOs. A high-current DC switch module based on the DirectETO can be realized by directly connecting ETOs in parallel without the bulky current sharing inductors used in other current-sharing solutions.
In order to achieve voltage stress suppression under high current conditions, the parasitic parameters, especially parasitic inductance in a high-current ETO switch module are studied. The Partial Element Equivalent Circuit (PEEC) method is used to extract the parasitics. Combined with the developed device model, the electrical interactions among multiple ETOs are investigated which results in structural modification for the solid-state DC switch module.
The electro-thermal model of the DC switch module and the heatsink subsystem is used to identify the "thermal runaway" phenomenon in the module that is caused by the negative temperature coefficient of the ETO's conduction drop. The comparative study of the electro-thermal coupling identifies a strongly-coupled thermal network that increases the stability of the thermal subsystem. The electro-thermal model is also used to calculate the DC and transient thermal limit of the DC switch module.
The high-current (5000A) DC switch module coupled with a solid state tripping unit is successfully applied as a high-speed, high-current solid-state DC circuit breaker. The experimental demonstration of a 5000A current interruption shows an interruption time of about 5 microseconds. This high-speed, high-current DC switch module can therefore be used in DC circuit breaker applications as well as other types of application, such as AC circuit breakers, transfer switches and fault current limiters.
Since the novel solid-state DC circuit breaker is able to extinguish the fault current even before it reaches an uncontrollable level, this feature provides a fast-acting, current-limiting protection scheme for power systems that is not possible with traditional circuit breakers. The potential impact on the power system is also discussed in this dissertation. / Ph. D.
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Gränsöverskridande interaktion i en Engineer to order-kontext : En studie om hur boundary object kan underlätta gränsöverskridande interaktionSeger, Janina, Tolstrup, Hanna January 2018 (has links)
Syfte – Studien syftade till att undersöka den interna interaktionen i en liten, tillverkande ETO-verksamhets kundorderprocess samt hur boundary object underlättar dess gränsöverskridande interaktion. För att uppfylla studiens syfte kommer följande frågeställningar att besvaras: Vad kännetecknar den gränsöverskridande interaktionen i en liten, tillverkande ETO-verksamhets kundorderprocess? Hur kan boundary object underlätta den gränsöverskridande interaktionen i en liten, tillverkande ETO-verksamhet? Metod – För att uppfylla studiens syfte har en fallstudie genomförts hos Premould AB. Via intervjuer och dokumentstudier har deras kundorderprocess undersökts och interaktionsobjekt i processen identifierats. Insamlad data låg sedan till grund för hur det teoretiska ramverket upprättades. Med hjälp av den empiriska insamlingen och det teoretiska ramverket har en analys genomförts som i sin tur genererat studiens resultat. Resultat – Genom att undersöka kundorderprocessen, i en ETO-verksamhet, har olika kännetecken för den gränsöverskridande interaktionen kunnat urskiljas. Interaktionsobjekt, som belyses som boundary object, har identifierats i processen. Boundary object kan underlätta den interna interaktionen om de används utefter den nivå av komplexitet av kunskapsridning som finns i gränssnitten mellan funktioner. Implikationer – Resultatet att boundary object underlättar den gränsöverskridande interaktionen ger ett praktiskt bidrag till små, tillverkande ETO-verksamheter. Genom valet av boundary object ska det gå att förenkla kunskapsspridning och genom det effektivisera arbetsprocesser. Det ges även ett teoretiskt bidrag till vidare forskning om boundary object i ETO-kontexter. Begränsningar – En av begränsningarna i studien är att det kan vara svårt att generalisera utifrån resultatet eftersom studien var av enfallsdesign. Gränsöverskridande interaktion är dessutom komplext att undersöka med strukturella metoder och det saknades därför möjlighet att djupt undersöka de identifierade interaktionsobjekten. Nyckelord – Engineer to order (ETO), gränsöverskridande interaktion, kunskapsgränser, kunskapsspridning, boundary object. / Purpose – The purpose of the study was to investigate the internal interaction of a small, manufacturing ETO-business's customer order process, as well as how boundary objects facilitate its boundary-crossing interaction. In order to fulfill the purpose of the study the following questions will be answered: What characterizes boundary-crossing interaction in a small, manufacturing ETO-business's customer ordering process? How can boundary objects facilitate boundary-crossing interaction in a small, manufacturing ETO-business? Method – To fulfil the purpose of the study, a case study has been conducted at Premould AB. Through interviews and document studies, their customer order process has been investigated and interaction objects in the process been identified. The collected data then formed a base for the establishment of the theoretical framework. With the empirical collection and the theoretical framework, an analysis has been conducted which, in turn, generated the results of the study. Findings – By examining the customer ordering process, in an ETO-business, different characteristics of boundary-crossing interaction has been identified. Interaction objects, which are used according to the principles of boundary objects, have been identified in the process. Boundary objects can facilitate internal interaction if used at the proper level of complexity of knowledge sharing found in the interfaces. Implications – The result that boundary objects facilitate boundary-crossing interaction provides a practical contribution to small, manufacturing ETO-business. Through the choice of boundary object used, it is possible to simplify knowledge sharing and make more effective work processes. There is also a theoretical contribution to further research on boundary objects in ETO-contexts. Limitations – One of the limitations of the study is that it can be difficult to generalize from the result, due to the use of a single-case design. Moreover, boundary-crossing interaction is complex to investigate with structural methods, and it was therefore difficult to closely investigate the identified objects. Keywords – Engineer to order (ETO), boundary-crossing interaction, knowledge boundaries, boundary object.
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Product structure modeling for ETO system product considering the product lifecycle : A case study of ABB Mine HoistZhang, Sumei January 2019 (has links)
In order to gain competitive advantages in markets, companies have provided a variety of customized products to satisfy customer-specific requirements, leading to not only a large amount of product data but also high cost, long lead-time and complexity of quality control. Efficient product data management throughout the product lifecycle has become increasingly crucial, of which product structure management is regarded as the most important constituent. The study took ABB Mine Hoist system as a case to investigate how to construct a generic product structure model fit for engineer-to-order system offerings with the consideration of their sales-delivery product lifecycle. The aim of the model is to facilitate the product-related information sharing and reuse across a company, and the integration of different business operations throughout the entire product lifecycle as well. Based on the current situation analysis of product data management on ABB Mine Hoist, three major issues were identified which need to be addressed in the formulation of a generic structure model: namely the integration of requirements of multiple disciplines; the consistency of product information throughout the product lifecycle; and the constant update of product repository. Through illustrating the formulation of ABB Mine Hoist generic structure model, the method of how to construct a generic product structure model for engineer-to-order system product was presented. The model was achieved by applying the framework of the step-based product model and was regarded as a result of integrating domain-specific requirements. The adaptive generic product structure model was then employed to display the role of this generic model in the different phases of a sales-delivery lifecycle. The model could serve as a “master concept” to transfer common product information in the product lifecycle. It’s expected to benefit the business of engineer-to-order system product through improving the integration of different disciplines, enhancing information exchange and reuse. It could also provide an abstract and conceptual basis for potential product repository to reinforce data consistency and completeness.
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Evapotranspiração e coeficientes de cultivo (KC) da cana-de-açúcar irrigada por gotejamento subsuperficial / Evapotranspiration and crop coefficients of subsurface drip irrigated sugar caneGonçalves, Fabricio Mota January 2010 (has links)
GONÇALVES, Fabrício Mota. Evapotranspiração e coeficientes de cultivo (KC) da cana-de-açúcar irrigada por gotejamento subsuperficial. 2010. 64 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola, Fortaleza-CE, 2010. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-06-28T16:59:16Z
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Previous issue date: 2010 / Sugar cane is one of the crops with the highest level of water consumption, with a high evapotranspiration demand throughout most of its cycle. Knowledge of the sugar cane water demand, the time that irrigation should be applied, and how to irrigate the crop are becoming increasingly important for the sustainable development of irrigated sugar cane cultivation, especially in areas of low water availability, as it is the case in northea stern Brazil. The experiment was carried out at the Curu Experimental Field (property of the Embrapa Tropical Agroindustry), located in the Curu-Paraipaba Irrig ation Project, city of Paraipaba-CE (3 ° 29 '20''S, 39 ° 9' 45''W and elevation 30m), in order to determine the evapotrans piration and crop coefficients (Kc) of sugarcane (Saccharum L. officinarium), subsurface drip-irrigated. It was used the SP 6949 sugar cane variety, planted in a spacing of 1.8 m between double rows and 0.4 m between rows within the double row. As to t he irrigation, we used one lateral water line for each double row, buried at a depth of 0.15 m, w ith self-compensating drip emitters, with a flow rate of 1 L h-1, spaced 0.5 m on the water line. The crop was irrigated daily and there were three fertigations per week. The irrigation de pth was periodically adjusted, keeping the soil water potential between -8 kPa to -20 kPa. The crop evapotranspiration (ETc) was determined using a wei ghing lysimeter with a surface area of 2.25 m 2. The reference evapotranspiration (ETo) was estimated by the FAO Penman-Monteith method. The durations of the phenological stages of cane sugar were estimated through analysis of soil cover, with the use of digital images. Durations of 31, 49, 237 and 118 days were observed, respectively for initial, crop development, mid-season and late season stages. The yields achieved within and outside the lysimeter were respectively 144.4 and 108.8 t ha -1 . The total ETc observed during the cycle of the sugar cane was 1074.1 m m, with maximum values of 6.6 mm d-1 during the mid-season stage. Observed Kc values for initial, mid-season and late season stages were respectively 0.23, 1 .03 and 0.50. In the crop development stage, the relationship between Kc and the (crop) soil cover was represented with good accuracy by a negative quadratic model. / A cana-de-açúcar é uma das culturas com maior consumo de água, apresentando uma alta demanda evapotranspirativa ao longo da maior parte do seu ciclo. O conhecimento das necessidades hídricas da cana-de-açúcar, do momento de aplicação da água requerida pela mesma e a forma de aplicação torna-se cada vez mais importante para o desenvolvimento sustentável da sua produção irrigada, principalmente em regiões de pouca disponibilidade hídrica, como é o caso da região Nordeste do Brasil. O experimento foi conduzido no Campo Experimental do Curu, pertencente à Embrapa Agroindústria Tropical localizado no Perímetro Irrigado Curu-Paraipaba, município de Paraipaba-CE (3° 29’ 20’’ S, 39° 9’ 45’’ W e altitude de 30 m), com o objetivo de determinar a evapotranspiração e os coeficientes de cultivo (Kc) da cana-de-açúcar (Saccharum officinarium L.), irrigada por gotejamento subsuperficial. Utilizou-se a variedade de cana SP 6949, plantada no espaçamento de 1,8 m entre fileiras duplas e 0,4 m entre linhas dentro da fileira dupla. Na irrigação utilizou-se uma linha lateral para cada fileira dupla, enterrada na profundidade de 0,15 m, com gotejadores autocompensantes, com vazão de 1 L h-1, espaçados de 0,5 m na linha. A cultura foi irrigada com freqüência diária e foram realizadas três fertirrigações por semana. A lâmina de irrigação foi ajustada periodicamente, mantendo-se o potencial de água no solo entre -8 kPa e -20 kPa. A evapotranspiração da cultura (ETc) foi determinada utilizando-se um lisímetro de pesagem com área superficial de 2,25 m2. A evapotranspiração de referência (ETo) foi estimada pelo método FAO Penman-Monteith. As durações das fases fenológicas da cana-de-açúcar foram estimadas por meio da análise da cobertura do solo pela cultura, determinada com o uso de imagens digitais. Foram observadas durações de 31, 49, 237 e 118 dias, para as fases inicial, de desenvolvimento, intermediária e final, respectivamente. A produtividade alcançada dentro e fora do lisímetro foi de 144,4 e 108,8 t ha-1, respectivamente. A ETc total observada durante o ciclo da cana-de-açúcar foi de 1.074,1 mm, com valores máximos da ordem de 6,6 mm d-1 durante a fase intermediária. Foram observados valores de Kc iguais a 0,23, 1,03 e 0,50, para as fases inicial, intermediária e final, respectivamente. Na fase de desenvolvimento vegetativo a relação entre o Kc e a cobertura do solo pela cultura foi representada com bastante exatidão por um modelo quadrático negativo.
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