Assessment of the potential impacts of plant traits across environments by combining global sensitivity analysis and dynamic modeling in wheat

A crop can be viewed as a complex system with outputs (e.g. yield) that are affected by inputs of genetic, physiology, pedo-climatic and management information. Application of numerical methods for model exploration assist in evaluating the major most influential inputs, providing the simulation model is a credible description of the biological system. A sensitivity analysis was used to assess the simulated impact on yield of a suite of traits involved in major processes of crop growth and development, and to evaluate how the simulated value of such traits varies across environments and in relation to other traits (which can be interpreted as a virtual change in genetic background). The study focused on wheat in Australia, with an emphasis on adaptation to low rainfall conditions. A large set of traits (90) was evaluated in a wide target population of environments (4 sites x 125 years), management practices (3 sowing dates x 2 N fertilization) and $CO_2$ (2 levels). The Morris sensitivity analysis method was used to sample the parameter space and reduce computational requirements, while maintaining a realistic representation of the targeted trait x environment x management landscape ($\sim$ 82 million individual simulations in total). The patterns of parameter x environment x management interactions were investigated for the most influential parameters, considering a potential genetic range of +/- 20% compared to a reference. Main (i.e. linear) and interaction (i.e. non-linear and interaction) sensitivity indices calculated for most of APSIM-Wheat parameters allowed the identifcation of 42 parameters substantially impacting yield in most target environments. Among these, a subset of parameters related to phenology, resource acquisition, resource use efficiency and biomass allocation were identified as potential candidates for crop (and model) improvement.Comment: 22 pages, 8 figures. This work has been submitted to PLoS On

Towards a methodical framework for comprehensively assessing forest multifunctionality

Funded by Deutsche Forschungsgemeinschaft. Grant Number: DFG FOR 891/1-3 National Natural Science Foundation of China. Grant Numbers: 30710103907, 30930005, 31170457, 31210103910 Swiss National Science Foundation (SNSF) Sino-German Centre for Research Promotion in Beijing. Grant Number: GZ 986Peer reviewedPublisher PD

A Distributed Surrogate Methodology for Inverse Most Probable Point Searches in Reliability Based Design Optimization

Surrogate models are commonly used in place of prohibitively expensive computational models to drive iterative procedures necessary for engineering design and analysis such as global optimization. Additionally, surrogate modeling has been applied to reliability based design optimization which constrains designs to those which provide a satisfactory reliability against failure considering system parameter uncertainties. Through surrogate modeling the analysis time is significantly reduced when the total number of evaluated samples upon which the final model is built is less than the number which would have otherwise been required using the expensive model directly with the analysis algorithm. Too few samples will provide an inaccurate approximation while too many will add redundant information to an already sufficiently accurate region. With the prediction error having an impact on the overall uncertainty present in the optimal solution, care must be taken to only evaluate samples which decrease solution uncertainty rather than prediction uncertainty over the entire design domain. This work proposes a numerical approach to the surrogate based optimization and reliability assessment problem using solution confidence as the primary algorithm termination criterion. The surrogate uncertainty information provided is used to construct multiple distributed surrogates which represent individual realizations of a lager surrogate population designated by the initial approximation. When globally optimized upon, these distributed surrogates yield a solution distribution quantifying the confidence one can have in the optimal solution based on current surrogate uncertainty. Furthermore, the solution distribution provides insight for the placement of supplemental sample evaluations when solution confidence is insufficient. Numerical case studies are presented for comparison of the proposed methodology with existing methods for surrogate based optimization, such as expected improvement from the Efficient Global Optimization algorithm

Performance Assessment of Feature Detection Algorithms: A Methodology and Case Study on Corner Detectors

In this paper we describe a generic methodology for evaluating the labeling performance of feature detectors. We describe a method for generating a test set and apply the methodology to the performance assessment of three well-known corner detectors: the Kitchen-Rosenfeld, Paler et al. and Harris-Stephens corner detectors. The labeling deficiencies of each of these detectors is related to their discrimination ability between corners and various of the features which comprise the class of noncorners

An integrated quantitative framework for supporting product design : the case of metallic moulds for injection

Tese de Doutoramento. Programa Doutoral em Engenharia Industrial e Gestão. Faculdade de Engenharia. Universidade do Porto. 201

A disposition of interpolation techniques

A large collection of interpolation techniques is available for application in environmental research. To help environmental scientists in choosing an appropriate technique a disposition is made, based on 1) applicability in space, time and space-time, 2) quantification of accuracy of interpolated values, 3) incorporation of ancillary information, and 4) incorporation of process knowledge. The described methods include inverse distance weighting, nearest neighbour methods, geostatistical interpolation methods, Kalman filter methods, Bayesian Maximum Entropy methods, etc. The applicability of methods in aggregation (upscaling) and disaggregation (downscaling) is discussed. Software for interpolation is described. The application of interpolation techniques is illustrated in two case studies: temporal interpolation of indicators for ecological water quality, and spatio-temporal interpolation and aggregation of pesticide concentrations in Dutch surface waters. A valuable next step will be to construct a decision tree or decision support system, that guides the environmental scientist to easy-to-use software implementations that are appropriate to solve their interpolation problem. Validation studies are needed to assess the quality of interpolated values, and the quality of information on uncertainty provided by the interpolation method

Few-Mode Transmission Technology for Ultra-High Capacity Optical Networks

Tesis por compendio[ES] En esta Tesis Doctoral, se propone diferentes técnicas de acoplo y conversión modal destinadas a aumentar la capacidad de transporte en sistemas de telecomunicaciones sobre fibra óptica. En particular, el objetivo principal es el desarrollo de la tecnología necesaria para conseguir una multiplexación modal utilizando un número limitado de modos, de manera controlada. Para ello, se estudian dos escenarios MDM con dos longitudes de onda distinta. Por un lado, usando la longitud de onda de 850 nm sobre SSMF favoreciendo la utilización de componentes ópticos y electro-ópticos de coste mucho menor que sus equivalentes en la banda C+L. Esta novedosa tecnología de transmisión permitirá una nueva generación de interconexiones ópticas de muy alta capacidad aplicable a enlaces chip-a-chip, a backplanes ópticos y también a clústeres de computación de altas prestaciones y centros de conmutación de red. Por otro lado, usando la longitud de onda de 1550 nm sobre guías ópticas basadas en SOI, es decir, Si (silicio) sobre sustrato de SiO2 (óxido de silicio) favoreciendo la utilización de dispositivos basados en tecnología integrada que ofrecen un menor tamaño, mejor repetibilidad y robustez que los dispositivos basados en fibra óptica. Para ello, se propone el uso de acopladores ópticos fusionados siendo un elemento indispensable a la hora de multiplexar y demultiplexar los distintos modos ópticos en un enlace MDM a 850 nm. Esta técnica permite multiplexar/demultiplexar los modos ópticos cuando el tipo de acoplador óptico utilizado es simétrico (DC, del inglés directional coupler), siendo necesario la utilización de un conversor de modos. También se estudia la posibilidad de convertir el modo óptico mediante la utilización de un acoplador óptico asimétrico (ADC, del inglés asymmetrical directional coupler), no siendo necesario utilizar un conversor de modos y simplificando el esquema MDM. Además, en esta tesis doctoral también se propone y evalúa el diseño de un conversor de modos mecánico basado en SSMF. Esta técnica permite obtener el primer modo de orden superior con una alta calidad y sin la necesidad de utilizar un ADC. Después de esto, se propone y evalúa la posibilidad de utilizar acopladores comerciales (diseñados a 1550 nm) a la longitud de onda de 850 nm permitiendo de esta forma reducir la necesidad de utilizar acopladores ópticos y conversores modales específicamente diseñados en dicha longitud de onda. Esta técnica reduciría los costes del sistema al necesitar un menor número de dispositivos y aprovechar los dispositivos diseñados a 1550 nm, siendo más económicos que los diseñados a 850 nm. En esta Tesis también se propone el uso de ADCs en guías strip basadas en SOI para la conversión y multiplexación de los modos ópticos desde la guia fundamental a la guia de dos modos, a la longitud de onda de 1550 nm. Para ello se estudia y demuestra experimentalmente diferentes diseños con el fin de obtener el diseño más robusto frente a las tolerancias de fabricación consiguiendo un rendimiento óptimo. Además, el uso de DCs sobre guías ridge es comúnmente utilizado y ofrece mejores prestaciones que el basado en guías strip, por ese motivo esta Tesis estudia y evalúa el uso de ADCs sobre guías ridge mediante el método de análisis de los índices efectivos de los supermodos par e impar. De esta forma se realiza una comparación entre los diseños óptimos de ambas estructuras (strip y ridge) con el objetivo de averiguar qué diseño ofrece mejores prestaciones. Por último, se propone y estudia el diseño de un acoplador grating capaz de multiplexar y demultiplexar los modos ópticos del modo fundamental y del primer orden superior desde la guia óptica a la fibra óptica y viceversa. Para ello se proponen diferentes diseños con el objetivo de conseguir un diseño más tolerante y eficiente frente a los errores por desalineamiento obteniendo un acoplo óptimo.[CA] En aquesta Tesi Doctoral, es proposen diferents tècniques d'acoblament i conversió modal destinades a augmentar la capacitat de transport en sistemes de telecomunicacions sobre fibra òptica. En particular, l'objectiu principal és el desenrotllament de la tecnologia necessària per a aconseguir una multiplexació modal utilitzant un número limitat de modes, de manera controlada. Per a això, s'estudien dos escenaris MDM amb dos longituds d'onda distinta. D'una banda, usant la longitud d'ona de 850 nm sobre SSMF afavorint la utilització de components òptics i electro-òptics de cost molt menor que els seus equivalents en la banda C+L. Aquesta nova tecnologia de transmissió permetrà una nova generació d'interconnexions òptiques de molt alta capacitat aplicable a enllaços chip-a-chip, a backplanes òptics i també a clústers de computació d'altes prestacions i centres de commutació de xarxa. D'altra banda, usant la longitud d'ona de 1550 nm sobre guies òptiques basades en SOI, és a dir, Si (silici) sobre substrat de SiO2 (òxid de silici) afavorint la utilització de dispositius basats en tecnologia integrada que ofereixen una menor grandària, millor repetibilitat i robustesa que els dispositius basats en fibra òptica. Per a això, es proposa l'ús d'acobladors òptics fusionats sent un element indispensable a l'hora de multiplexar i demultiplexar els distints modes òptics en un enllaç MDM. Aquesta tècnica permet multiplexar/demultiplexar els modes òptics quan el tipus d'acoblador òptic utilitzat és simètric (DC, de l'anglès directional coupler), sent necessari la utilització d'un convertidor de modes. També s'estudia la possibilitat de convertir el mode òptic per mitjà de la utilització d'un acoblador òptic asimètric (ADC, de l'anglès asymmetrical directional coupler), no sent necessari utilitzar un convertidor de modes i simplificant l'esquema MDM. Es mes, en aquesta tesi doctoral també es proposa i avalua el disseny d'un convertidor de modes mecànic basat en SSMF. Aquesta tècnica permet obtindre el primer mode d'orde superior amb una alta qualitat sense la necessitat d'utilitzar un ADC. Després d'açò, es proposa i avalua la possibilitat d'utilitzar acobladors comercials (dissenyats a 1550 nm) a la longitud d'ona de 850 nm permetent d'esta manera reduir la necessitat d'utilitzar acobladors òptics i convertidors modals específicament dissenyats en la dita longitud d'ona. Aquesta tècnica reduiria els costos del sistema al necessitar un menor nombre de dispositius i aprofitant els dispositius dissenyats a 1550 nm, sent més econòmics que els dissenyats a 850 nm. En aquesta Tesi també es proposa l'ús de ADCs en guies strip basades en SOI per a la conversió i multiplexació dels modes òptics des de la guia fonamental a la guia de dos modes, a la longitud d'ona de 1550 nm. Per a això s'estudia i demostra experimentalment diferents dissenys a fi de obtindré el disseny més robust enfront les toleràncies de fabricació aconseguint un rendiment òptim. A més, l'ús de DCs sobre guies ridge és comunament utilitzat i ofereix millors prestacions que el basat en guies strip, per eixe motiu aquesta Tesi estudia i avalua l'ús de ADCs sobre guies ridge per mitjà del mètode d'anàlisi dels índexs efectius dels supermodes parell i imparell. D'aquesta manera es realitza una comparació entre els dissenys òptims de les dos estructures (strip i ridge) amb l'objectiu d'esbrinar quin disseny ofereix millors prestacions. Finalment, es proposa i estudia el disseny d'un acoblador grating capaç de multiplexar i demultiplexar els modes òptics del mode fonamental i del primer orde superior des de la guia òptica a la fibra òptica i viceversa. Per a això es proposen diferents dissenys amb l'objectiu d'aconseguir un disseny més tolerant i eficient enfront dels errors per desalineament obtenint un acoblament òptim.[EN] In this Ph.D. thesis, different mode coupling and mode conversion techniques with the aim to increase the transport capacity in telecommunications systems over optical fiber are proposed. Concretely, the main aim is the development of the technology to achieve MDM using a limited controlled number of modes. Two different MDM scenarios based on two distinct wavelengths have been considered. On one hand, using the 850 nm wavelength over SSMF favors the use of optical and electro-optical devices with costs much lower than their equivalent in the C+L band. This novel transmission technology enables a new generation of very high capacity optical interconnections applicable to chip-to-chip links, to optical backplanes, and also to high-performance computing clusters and network switching centre interconnections. On the other hand, using the 1550 nm wavelength over optical waveguides based on SOI, i.e., Si (Silicon) above SiO2 substrate (silicon oxide), allows the use of integrated devices offering a less size, better repeatability and robustness in comparison with the optical fiber devices. Fused fiber couplers are proposed as key elements to (de)multiplex different fiber modes in a MDM link at 850 nm. The use of a symmetric directional coupler (DC) as a (de)multiplexer requires the use of an additional mode converter. The use of an asymmetrical directional coupler (ADC) as optical (de)multiplexer and mode converter is proposed, avoiding the necessity of an additional mode converter and simplifying the MDM scheme. Furthermore, in this Ph.D. thesis it is also proposed and evaluated the design of a mechanical mode converter at 850 nm using a SSMF. This technique permits to obtain the first high order mode with high quality and without the necessity of using an ADC. After that, it is analyzed and investigated the employment of commercial optical couplers (designed at 1550 nm) at 850 nm wavelength operation, thus avoiding the use of optical couplers and mode converters specifically designed at 850 nm wavelength. The MDM system costs are reduced as fewer devices are required and commercial components designed at 1550 nm are cheaper than the counterparts at 850 nm. In this Ph.D. thesis it is also considered the employment of ADCs over strip waveguides based on SOI technology for the conversion and multiplexing of the optical modes, from single-mode waveguide to high order mode waveguide at the 1550 nm wavelength. Thus, it has been studied and experimentally investigated different designs aimed to achieve the most robust configuration, in which the yield is less affected by the fabrication tolerances. Furthermore, the use of DCs over ridge waveguides is commonly employed and it offers better performance than strip waveguides. For this reason, the Ph.D. thesis studies and evaluates the use of ADCs with ridge waveguides by considering the effective refractive indexes of the even and odd supermodes analysis. In this way, a comparison between strip and ridge structures is done in order to find the optimum design that offer the best features. Finally, it is analyzed the design of a grating coupler capable of multiplexing and demultiplexing the fundamental and the high order mode from the waveguide to the optical fiber and vice versa. Thus, different designs are evaluated in order to achieve a design more robust and efficient to the coupling misalignments.García Rodríguez, D. (2018). Few-Mode Transmission Technology for Ultra-High Capacity Optical Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115938TESISCompendi