Dynamic Reserve and Transmission Capacity Allocation in Wind-Dominated Power Systems

The large shares of wind power generation in electricity markets motivate higher levels of operating reserves. However, current reserve sizing practices fail to account for important topological aspects that might hinder their deployment, thus resulting in high operating costs. Zonal reserve procurement mitigates such inefficiencies, however, the way the zones are defined is still open to interpretation. This paper challenges the efficiency of predetermined zonal setups that neglect the location of stochastic power production in the system, as well as the availability, cost and accessibility of flexible generating units. To this end, we propose a novel reserve procurement approach, formulated as a two-stage stochastic bilevel model, in which the upper level identifies a number of contiguous reserve zones using dynamic grid partitioning and sets zonal requirements based on the total expected operating costs. Using two standard IEEE reliability test cases, we show how the efficient partitioning of reserve zones can reduce expected system cost and promote the integration of stochastic renewables.Comment: Submitted to IEEE Transactions on Power Systems on the 20th of March 202

Statistical physics approaches to the complex Earth system

Global climate change, extreme climate events, earthquakes and their accompanying natural disasters pose significant risks to humanity. Yet due to the nonlinear feedbacks, strategic interactions and complex structure of the Earth system, the understanding and in particular the predicting of such disruptive events represent formidable challenges for both scientific and policy communities. During the past years, the emergence and evolution of Earth system science has attracted much attention and produced new concepts and frameworks. Especially, novel statistical physics and complex networks-based techniques have been developed and implemented to substantially advance our knowledge for a better understanding of the Earth system, including climate extreme events, earthquakes and Earth geometric relief features, leading to substantially improved predictive performances. We present here a comprehensive review on the recent scientific progress in the development and application of how combined statistical physics and complex systems science approaches such as, critical phenomena, network theory, percolation, tipping points analysis, as well as entropy can be applied to complex Earth systems (climate, earthquakes, etc.). Notably, these integrating tools and approaches provide new insights and perspectives for understanding the dynamics of the Earth systems. The overall aim of this review is to offer readers the knowledge on how statistical physics approaches can be useful in the field of Earth system science

Statistical physics approaches to the complex Earth system

Global warming, extreme climate events, earthquakes and their accompanying socioeconomic disasters pose significant risks to humanity. Yet due to the nonlinear feedbacks, multiple interactions and complex structures of the Earth system, the understanding and, in particular, the prediction of such disruptive events represent formidable challenges to both scientific and policy communities. During the past years, the emergence and evolution of Earth system science has attracted much attention and produced new concepts and frameworks. Especially, novel statistical physics and complex networks-based techniques have been developed and implemented to substantially advance our knowledge of the Earth system, including climate extreme events, earthquakes and geological relief features, leading to substantially improved predictive performances. We present here a comprehensive review on the recent scientific progress in the development and application of how combined statistical physics and complex systems science approaches such as critical phenomena, network theory, percolation, tipping points analysis, and entropy can be applied to complex Earth systems. Notably, these integrating tools and approaches provide new insights and perspectives for understanding the dynamics of the Earth systems. The overall aim of this review is to offer readers the knowledge on how statistical physics concepts and theories can be useful in the field of Earth system science

Estudo numérico e observacional de processos da circulação na margem Ibérica noroeste

The Western Iberian Margin (WIM) is characterized by summer upwelling and winter downwelling, with alternating conditions at short time scales throughout the year. During summer upwelling, o shore-flowing jets may develop on the shelf and give rise to long, narrow upwelling filaments extending far from coast. The aim of this thesis is to study the WIM hydrography and circulation, using both an ensemble of observations consisting of in situ cruises and remote sensing on one hand, and state-of-the-art model configurations using ROMS-AGRIF on the other hand. Three distinct approaches were carried out to assess different time and spatial scales: (1) Assessment of the mesoscale filaments field in the summer for the years 2001-2010 using sea surface temperature from satellite and modeling; (2) The shelf response to upwelling/relaxation cycles on the Northwestern Iberian Margin (NWIM) in July 2009 from an extensive oceanographic cruise; (3) The shelf circulation and hydrography during an annual cycle (November 2008-December 2009) through monthly cruises and a high resolution modeling configuration. Filaments were generally found anchored to the main bathymetric and coastal features but off the smoother northern coast of the WIM, their locations were more variable. There was a clear relation between upwelling-favorable wind strength and the number and length of filaments in the southern region, although the relation was weaker in the northern region. Filaments were also related to eddies during periods of weak winds. Along the smoother northern coast in July 2009, under upwelling favorable winds, an upwelling center was found from cape Silleiro to Porto, where the surface temperature was colder than the neighboring regions. As these winds relaxed, persistent poleward flow developed, with an origin south of the upwelling center and consisting in an inner-shelf tongue of warm waters. Furthermore, study of the full annual cycle for the NWIM around cape Silleiro, between November 2008 to December 2009, revealed the importance of the upwelling/downwelling cycles on the shelf circulation and hydrography. In autumn/winter seasons, poleward flows occur on the shelf due to periods of downwelling favorable highly variable winds, and is formed the Western Iberian Buoyant Plume (WIBP) originated by the higher river flows. This situation occurred in autumn 2009 but not in autumn 2008, when unusually intense upwelling was found, delaying the downwelling favorable period to the winter season (January-February 2009). Upwelling prevailed in spring and summer 2009, although the upwelling front was fully developed only in August and September 2009. This was because in June and July downwelling events were associated with the generation of an inner shelf poleward flow, transporting warm waters. The numerical model configuration used in this work was validated with the set of observations and hence, its applicability to regional multidisciplinary studies was demonstrated.A Margem Ibérica Ocidental (WIM) caracteriza-se pelo afloramento durante o verão e convergência no inverno, alternando entre estas condições em curtas escalas temporais ao longo do ano. Durante o verão, com afloramento, podem-se desenvolver focos de correntes na direção ao largo que dão lugar a lamentos longos e estreitos que se estendem para longe da costa. Esta tese tem como objetivo o estudo da hidrografia e circulação na WIM, através do processamento de dados observacionais in situ e de detecção remota, e do desenvolvimento de configurações regionais de modelação a alta resolução, com o sistema ROMSAGRIF. Três abordagens distintas foram levadas a cabo para avaliar processos a diferentes escalas espaciais e temporais: (1) Análise do campo de lamentos de mesoescala no verão de 2001 a 2010 na WIM, utilizando a temperatura de superfície do mar a partir de imagens de satélite e de modelação oceânica; (2) A resposta do oceano na plataforma continental aos ciclos de upwelling e downwelling através de uma campanha oceanográfica na região Noroeste da Península Ibérica em julho de 2009; (3) A circulação e a hidrografia na plataforma continental durante um ciclo anual (novembro 2008-dezembro 2009) através de campanhas mensais e de uma configuração regional de alta resolução. Os lamentos encontraram-se geralmente ancorados às principais protuberâncias batimétricas e costeiras, mas onde a linha de costa é mais retilínea na região norte da WIM, as suas localizações foram mais variáveis. Observou-se uma clara relação entre a intensidade de ventos favoráveis ao afloramento e o número e comprimento dos lamentos a sul, sendo esta menos clara a norte. Foi também encontrada uma relação entre os lamentos e vórtices de mesoescala em períodos de ventos fracos. A norte, ao longo da costa mais retilínea, em julho de 2009 sob ventos de norte, um centro de afloramento estendeu-se desde o cabo Silleiro até ao Porto onde a temperatura era inferior à região circundante. Resultante do relaxamento dos ventos de norte, desenvolveu-se uma corrente em direção ao polo na plataforma interna com advecção de águas mais quentes com origem a sul do centro de afloramento. O estudo do ciclo anual, realizado no período de novembro 2008 a dezembro 2009 na região do cabo Silleiro, revelou a importância dos ciclos de afloramento/convergência na circulação e hidrografia na plataforma continental. Nas estações de outono/inverno, correntes para o polo ocorrem na plataforma continental associadas a períodos de convergência com ventos variáveis, e são formadas plumas de água doce provenientes do aumento do caudal dos rios. Esta situação ocorreu no outono de 2009 mas não no outono de 2008, quando foi observado afloramento intenso, adiando o período de convergência para o inverno (janeiro-fevereiro 2009). Em 2009 o afloramento foi predominante na primavera e no verão, no entanto a frente de afloramento só se desenvolveu completamente em agosto e setembro. Em junho e julho, advecção de águas quentes de sul, associada a eventos de convergência, atrasaram o desenvolvimento da frente. A configuração do modelo numérico desenvolvido neste trabalho foi validada com o conjunto de dados observacionais, o que demonstra a sua aplicabilidade a estudos multidisciplinares regionais.Programa Doutoral em Ciência, Tecnologia e Gestão do Ma

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 130, July 1974

This special bibliography lists 291 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1974

Study of Climate Variability Patterns at Different Scales – A Complex Network Approach

Das Klimasystem der Erde besteht aus zahlreichen interagierenden Teilsystemen, die sich über verschiedene Zeitskalen hinweg verändern, was zu einer äußerst komplizierten räumlich-zeitlichen Klimavariabilität führt. Das Verständnis von Prozessen, die auf verschiedenen räumlichen und zeitlichen Skalen ablaufen, ist ein entscheidender Aspekt bei der numerischen Wettervorhersage. Die Variabilität des Klimas, ein sich selbst konstituierendes System, scheint in Mustern auf großen Skalen organisiert zu sein. Die Verwendung von Klimanetzwerken hat sich als erfolgreicher Ansatz für die Erkennung der räumlichen Ausbreitung dieser großräumigen Muster in der Variabilität des Klimasystems erwiesen. In dieser Arbeit wird mit Hilfe von Klimanetzwerken gezeigt, dass die Klimavariabilität nicht nur auf größeren Skalen (Asiatischer Sommermonsun, El Niño/Southern Oscillation), sondern auch auf kleineren Skalen, z.B. auf Wetterzeitskalen, in Mustern organisiert ist. Dies findet Anwendung bei der Erkennung einzelner tropischer Wirbelstürme, bei der Charakterisierung binärer Wirbelsturm-Interaktionen, die zu einer vollständigen Verschmelzung führen, und bei der Untersuchung der intrasaisonalen und interannuellen Variabilität des Asiatischen Sommermonsuns. Schließlich wird die Anwendbarkeit von Klimanetzwerken zur Analyse von Vorhersagefehlern demonstriert, was für die Verbesserung von Vorhersagen von immenser Bedeutung ist. Da korrelierte Fehler durch vorhersagbare Beziehungen zwischen Fehlern verschiedener Regionen aufgrund von zugrunde liegenden systematischen oder zufälligen Prozessen auftreten können, wird gezeigt, dass Fehler-Netzwerke helfen können, die räumlich kohärenten Strukturen von Vorhersagefehlern zu untersuchen. Die Analyse der Fehler-Netzwerk-Topologie von Klimavariablen liefert ein erstes Verständnis der vorherrschenden Fehlerquelle und veranschaulicht das Potenzial von Klimanetzwerken als vielversprechendes Diagnoseinstrument zur Untersuchung von Fehlerkorrelationen.The Earth’s climate system consists of numerous interacting subsystems varying over a multitude of time scales giving rise to highly complicated spatio-temporal climate variability. Understanding processes occurring at different scales, both spatial and temporal, has been a very crucial problem in numerical weather prediction. The variability of climate, a self-constituting system, appears to be organized in patterns on large scales. The climate networks approach has been very successful in detecting the spatial propagation of these large scale patterns of variability in the climate system. In this thesis, it is demonstrated using climate network approach that climate variability is organized in patterns not only at larger scales (Asian Summer Monsoon, El Niño-Southern Oscillation) but also at shorter scales, e.g., weather time scales. This finds application in detecting individual tropical cyclones, characterizing binary cyclone interaction leading to a complete merger, and studying the intraseasonal and interannual variability of the Asian Summer Monsoon. Finally, the applicability of the climate network framework to understand forecast error properties is demonstrated, which is crucial for improvement of forecasts. As correlated errors can arise due to the presence of a predictable relationship between errors of different regions because of some underlying systematic or random process, it is shown that error networks can help to analyze the spatially coherent structures of forecast errors. The analysis of the error network topology of a climate variable provides a preliminary understanding of the dominant source of error, which shows the potential of climate networks as a very promising diagnostic tool to study error correlations

Spatial runner : environmental and musical exposure effects on runners through an idealized routing network

Physical activities such as running have previously been proven to be positive on the health of individuals who partake in such activities. Further studies have separately analyzed the positive benefits of natural environments, such as forests, and positive effects of music on runners. This study evaluates how the presence or absence of such natural environments with and without musical stimuli effect the stress levels of individuals both physically and psychologically while running a predetermined route in the real world. Spatially Turn-Restricted Weighting Algorithm (STRWA) was created to solve the route creation criteria required of this study. The results of several analysis, both at the macro and micro levels of the study area, show that natural environments give lower physical stress levels than ones which have more urban characteristics. Additionally, music exposure further increases the positive feeling felt by a runner while increasing running speeds and only mildly increasing heart rate.Physical activities such as running have previously been proven to be positive on the health of individuals who partake in such activity. It has been further shown that runners who are exposed to high tempo music encounter faster running speeds and better psychological feeling levels. This study has evaluated how the presence or absence of such natural environments with and without musical stimuli effect the stress levels of individuals both physically and psychologically. In order to evaluate these differences, a real-world routing scenario was created. This routing scenario was created by an algorithm developed through this study and based on previous routing algorithms found commonly in spatial analysis. This algorithm considered vegetation and urban criteria in the landscape as well as placed restrictions on how runners could be tested and aptly named Spatially Turn-Restricted Weighting Algorithm or STRWA. This algorithm gave two separate running routes, one which was urban centric and the other densely vegetated centric. Where both of these were tested with and without the participants listening to high tempo music. The results of this study, in which analysis was conducted at both the macro and micro levels of the study area showed that natural environments induced lower physical stress levels among the participants than areas with higher urban characteristics. Additionally, music exposure increased the positive feeling felt by the runners while simultaneously increasing running speeds with mild increases in heart rate

Statistical analysis and intercomparison of WAM model data with global ERS-1 SAR wave mode spectral retrievals over 3 years

Ocean wave spectra were retrieved from a set of ERS-1 synthetic aperture radar (SAR) wave mode (SWM) spectra between January 1993 and December 1995. An assessment is given of the SWM data quality and the retrieval performance as well as the operational feasibility of the retrieval algorithm. Sensitivity studies are performed to demonstrate the weak residual dependence of the retrieval on the first-guess input spectrum. The mean spectral parameters of the SWM retrievals are compared with spectral parameters from collocated wave model (WAM) spectra. The time series of SWM-retrieved and WAM-derived monthly mean significant wave heights H-s in various ocean basins show good overall agreement but with a small systematic underestimation of H-s by the WAM. A decomposition of the wave spectra into wind sea and swell reveals an average 10% overprediction of the wind sea by the WAM while swell is underpredicted by 20-30%. The positive wind-sea bias exhibits no clear wave height dependence, while the negative swell bias decreases with swell wave height. This could be due to a too strong damping in the WAM at low frequencies. Detailed regional investigations point to the existence of smaller-scale phenomena, which may not be adequately reproduced by the WAM at the present resolution of the wind forcing. Finally, an intercomparison is made of the observed and modeled azimuthal cutoff length scales, and global distributions are investigated. Ratios of the observed azimuthal cutoff wavenumber to the mean azimuthal wavenumber component indicate that about 75% of the swell can be directly resolved by the SAR, while about 70% of the wind sea lies at least partially beyond the cutoff

Modeling of the polar ionosphere in the inertial corotating frame

Thesis (Ph.D.) University of Alaska Fairbanks, 1996The ionospheric model presented in this thesis is developed from first principles. It is a three-dimensional and time-dependent model that covers the region poleward from 50 degrees of geographic latitude and extends to the height range of 80-500 km. In this model, equations of continuity, motion, and energy balance are self-consistently solved for the densities of 7 ion species \lbrack O\sp+(\sp4S,\ \sp2D,\ \sp2P),\ NO\sp+,\ O\sb2\sp+,\ N\sb2\sp+,\ N\sp+\rbrack and electrons. The model accounts for 40 photochemical processes, the neutral wind drag with its shear, electromagnetic E $\times$ B-drift, and field-aligned ambipolar diffusion. The background thermospheric parameters here are derived from the VSH/MSIS models. Minor species NO,\ N(\sp4S,\ \sp2D) and their molecular and eddy diffusion transfer in the lower ionosphere are considered in this model. Energy balance equations for isotropic electron and ion temperatures are solved. including electron thermal conduction and Joule heating. The model is applicable to a limited polar region (hence the curvature is neglected) and the equations are solved in the corotating Cartesian frame with an azimuthal equidistant projection of all parameters and point-by-point transformation of the inputs specified in the geomagnetic frame. The regular grid has a scaleable resolution; the workstation version of the code presented in this thesis has achieved 100 x 100 km horizontal resolution. The algorithm maintains numerical stability for variable time steps in the range from 10-15 minutes to 1-2 minutes, allowing a flexible time coverage. This effective algorithm and even spatial coverage of the regular grid saves significant computational resources. The model output realistically represents seasonal changes and other large-scale polar ionospheric features such as the abundant day-side ionization, the polar cap tongue of ionization, the auroral oval, the polar hole, and ionospheric troughs of different origins. Ionospheric simulations developed in response to different IMF variations demonstrate destruction of continuous polar cap structures and the creation of "patches" of ionized plasma. Several model simulations have shown good overall agreement with observed ionospheric events