In this thesis, we investigate impulsive differential systems with delays of the form And more generally of the form The dissertation consists of five chapters. The first chapter serves as introduction, contains preliminary considerations and assertions that will be encountered in the sequel. In chapter 2, we construct the adjoint systems and obtain the variation of parameters formulas of the solutions in terms of fundamental matrices. The asymptotic behavior of solutions of systems satisfying the Perron condition is investigated in chapter 3. In chapter4, we give a result that characterizes the behavior of solutions in the case there is a bounded solution. Moreover, a necessary and sufficient condition for the existence of periodic solutions is obtained. In the last chapter, a series of consequences on the existence of periodic solutions of functionally equivlent impulsive systems with delays is established.

The main function of the power grid is to transfer electric energy from generating facilities to consumers. To have a reliable and economical supply of electricity, large amounts of electric energy often have to be transferred over long distances. The transmission system has a limited capacity to transfer electric power, called the transfer capacity. Severe system failures may follow if the transfer capacity is reached during operation. Due to uncertainties, such as the random failure of system components, the transfer capacity for the near future is not readily determinable. Also, due to market principles, and reaction times and ramp rates of production facilities, power flow control is not fully flexible. Therefore, a transfer limit, which is below the transfer capacity, is decided and preventative actions are taken when the transfer reaches this limit. In this thesis an approach to deciding an optimal strategy for power flow control through activation of regulating bids on the regulating power market is outlined. This approach leads to an optimal definition of transfer limits as the boundary between the domain where no bid should be activated and the domains where bids should be activated. The approach is based on weighing the expected cost from system failures against the production cost. This leads to a stochastic impulse control problem for a Markov process in continuous time. The proposed method is a novel approach to decide transfer limits in power system operation. The method is tested in a case study on the IEEE 39 bus system, that shows promising results. In addition to deciding optimal transfer limits, it is also investigated how the transfer capacity can be enhanced by controlling components in the power system to increase stability. / QC 20111010

Thesis (M.A.)--Baylor University, 2008. / Includes bibliographical references (p. 41-47).

Thesis (M.S.)--Mississippi State University. Department of Psychology. / Title from title screen. Includes bibliographical references.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This work in this study covers a powerful technique to derive propagation and scattering information in an expedient fashion. Expedient because time-domain (TD) data gathers a broad spectrum in a single transmitted pulse. TD has been criticised because of a lack of dynamic range, which has now been overcome by the direct sampling system, RATTY and RTA. This study focuses on the investigation of a TD metrology system, to assist with the characterisation of MeerKAT systems. The elementary components of the system include a fast-rising impulse generator that was coupled with an impulse radiating antenna (IRA). The system was calibrated and tested before practical measurements and preliminary testing in the Karoo were done. For TDmetrology a larger bandwidth accelerates measurements without the loss of accuracy. The pulse generator’s (PG’s) fundamental components are an avalanche transistor and a step recovery diode (SRD), to sharpen the leading edge of the pulse. Improving the rise-time of a pulse increases its bandwidth in the spectrum. The external circuitry around these components is pivotal and it determines the shape, amplitude and rise-time of the pulse. In the course of the investigation, the general circuitry around the PG was improved to obtain the best possible pulse for measurements inside a reverberation chamber (RC) and for measurements in the Karoo. In light of this, a second and third PG source were obtained. For measurements in the Karoo, a larger amplitude pulse was required to increase the spectral content and this is essential for propagation measurements over distance and the shielding effectiveness (SE) of structures. Stacking avalanche transistors allow larger amplitude pulses and it improves the dynamic range of the spectrum. A PG incorporating stacked avalanche transistors, was designed, built and measured to assist with RC and small-scale field measurements in the Karoo. The third PG was bought for the practical measurements in the Karoo. The PG produces kilovolt pulses with pico-second rise-times that extend the spectral range of the current PGs at our disposal. With these PGs, an antenna is required for the radiation of impulse-like transients. The IRA is a high-gain large-bandwidth antenna. The IRA consists of a parabolic reflector, conical-plate transmission lines that are terminated through resistors onto the dish, and a feeding balun. The IRA design was thoroughly discussed and a first model for metrology was designed, measured and optimised. The IRA was also simulated with computation software code, FEKO. Before deployment of theTDsystem, calibration and characterisation measurements are required. The measuring devices used within this study were sampling oscilloscopes and direct sampling systems. The limitations of each device were explored and are discussed. The final measurements that were conducted contribute to work related to the SKA. This incorporated antenna pattern calibration, propagation over distance and the SE of a berm built from Karoo soil. The system investigated the propagation attenuation over the Karoo soil and vegetation, with great promise. A broad spectrum was measured over a few kilometres and compared to free-space loss. The SE of the berm covered the same spectral bandwidth. In this measurement, scattering effects and knife-edge diffraction were observed. / AFRIKAANSE OPSOMMING: Die werk in hierdie studie dek ’n kragtige tegniek wat gebruik kan word om die voortplanting en die verstrooiingsinligting van elektromagnetiese golwe op ’n voordelige manier af te lei. Dit is voordelig, want tydgebieddata versamel ’n wye spektrum in ’n enkele oordraagbare puls. Tydgebied is in die verlede baie gekritiseer omdat dit ’n dinamiese reikwydte kortkom en dit is nou oorwin deur die direkte steekproefnemingstelsel, RATTY en RTA. Hierdie studie fokus op die ondersoek van ’n tydgebiedmetingssisteem en dit help met die karakterisering van MeerKAT sisteme. Die elementêre komponente van die sisteem bestaan uit ’n vinnig-stygende impulsgenerator wat gekoppel is aan ’n impulsuitstralende-antenna (IRA). Die sisteem is gekalibreer en getoets voordat praktiese metings en toetse in die Karoo uitgevoer kon word. Vir tydgebiedmetings versnel ’n groter bandwydte die metings sonder om die akkuraatheid daarvan te beïnvloed. Die pulsgenerator se fundamentele komponente is ’n stortvloedtransistor en ’n stap-herstel diode (SRD) wat die voorpunt van die puls verskerp. Die eskterne stroombaan rondom hierdie komponente is noodsaaklik en dit bepaal die vorm, amplitude en die stygtyd van die puls. Deur die loop van hierdie ondersoek is die algemene stroombaan rondom die puls verbeter, om die beste moontlike puls vir metings binne in die weerkaatsingskamer en vir metings in die Karoo, te verkry. Na aanleiding van dit is ’n tweede en derde pulsgenerator bron verkry. Vir die metings in die Karoo is ’n puls met ’n groter amplitude vereis om die spektrale inhoud te vermeerder. Dit is noodsaaklik vir elektromagnetiese golf voortplantingsmetings oor afstand asook die beskermings effektiwiteit (SE) van die strukture. Stapel-stortvloed transistors skep pulse met groter amplitudes en dit verbeter die dinamiese reikwydte van die spektrum. ’n Pulsgenerator wat gestapelde stortvloedtransistors insluit is ontwerp, gebou en gemeet om te help met metings in die weerkaatsingskamer en kleinskaal veldmetings in die Karoo. Die derde pulsgenerator is gekoop vir praktiese metings in die Karoo. Die pulsgenerator vervaardig kilovolt pulse met pikosekond stygtye, wat die reikwydte van die spektrum van ons huidige puls uitbrei. Hierdie pulsgenerators vereis ’n antenna vir die uistraling van impulsagtige seine. Die IRA is ’n hoë-wins, groot-bandwydte antenna. Die IRA bestaan uit ’n paraboliese weerkaatser, konieseplaat transmissielyne wat deur weerstande op die skottel getermineer word, asook ’n voedings "balun". Die IRA ontwerp is deeglik bespreek en ’n model is ontwerp, gemeet en verbeter. Die IRA is ook gesimuleer met behulp van ’n rekenaarsagtewareprogram, FEKO. Voordat die tydgebiedsisteem benut kan word, moet dit gekalibreer word en karakteriseringsmetings moet ook daarmee uitgevoer word. Die meetinstrumente wat in hierdie studie gebruik is, is steekproefneming-ossilloskope en direkte steekproefneming-sisteme. Die tekortkominge van elke instrument is ondersoek en bespreek. Die finale meting wat uitgevoer is, dra by tot die werk wat geassosieer word met die SKA. Dit behels antennapatroonkalibrasie, voortplanting van elektromagnetiese golwe oor afstand en die SE van ’n "berm"wat gebou is uit Karoo-grond. Hierdie sisteem is gebruik om die voortplantings-verswakking oor die Karoo-grond en plantegroei te ondersoek en dit lyk baie belowend. ’nWye spektrumis oor ’n paar kilometer gemeet en dit is met wrywinglose ruimte vergelyk. Die SE van die "berm"het dieselfde spektrale bandwydte gedek. In hierdie meting is verstrooiingseffekte en mespunt-diffraksie waargeneem.

In the field of empirical macroeconomics factor-augmented vector autoregressive (FAVAR) models have become a popular tool in explaining how economic variables interact over time. FAVAR is based upon a data-reduction step using factor estimation, which are then employed in a vector autoregressive model. This paper aims to study alternative methods regarding factor estimation. More precisely, we compare the generally used principal component method with the uncomplicated common correlated effect estimation. Results show low divergence between the two factor estimation methods employed, indicating interchangeability between the two estimation approaches.

[pt] Este estudo busca analisar o efeito do ambiente do varejo aeroportuário no comportamento do consumidor nas compras não planejadas. Foi utilizado o modelo conceitual de Mohan (2013), com a finalidade de testar tanto os elementos inerentes à loja (música, iluminação, lay out e atendentes) quanto as características individuais dos consumidores no que tange o lado afetivo, tanto o positivo quanto o negativo, assim como a necessidade de compra de determinado produto. Foi enviado por e-mail um survey para os clientes que compraram no Free Shop na loja do desembarque de São Paulo dentro do mês de janeiro 2014. Os resultados do estudo indicam a importância do ambiente da loja e principalmente da relevância dos atendentes dentro do modelo estudado. / [en] This study analyzes the effect of airport retail environment on consumer behavior in unplanned purchases. The conceptual model of Mohan (2013) was used for the purpose we test both the both the positive elements inherent to the store (music, lighting, lay out and attendants) and the individual characteristics of consumers regarding the affective side as negative, as well as the need to purchase a particular product. Was sent by e-mail a survey to customers who bought in Duty Free in arrival from Sao Paulo to store at least 1 month. The study results show how this set of elements within the dynamic purchasing influence consumption.

The present thrust in the electronics industry towards integrating multiple functions on a single chip while operating at very high frequencies has highlighted the need for efficient Electronic Design Automation (EDA) tools to shorten the design cycle and capture market windows. However, the increasing complexity in modern circuit design has made simulation a computationally cumbersome task. The notion of model order reduction has emerged as an effective tool to address this difficulty. Typically, there are numerous approaches and several issues involved in the implementation of model-order reduction techniques. Among the important ones of those issues is the problem of determining a suitable order (or size) for the reduced system. An optimal order would be the minimal order that enables the reduced system to capture the behavior of the original (more complex and larger) system up to a user-defined frequency. The contribution presented in this thesis describes a new approach aimed at determining the order of the reduced system. The proposed approach is based on approximating the impulse response of the original system in the time-domain. The core methodology in obtaining that approximation is based on numerically inverting the Laplace-domain of the representation of the impulse response from the complex-domain (s-domain) into the time-domain. The main advantage of the proposed approach is that it allows the order selection algorithm to operate directly on the time-domain form of the impulse response. It is well-known that numerically generating the impulse response in the time-domain is very difficult and its not impossible, since it requires driving the original network with the Dirac-delta function, which is a mathematical abstraction rather than a concrete waveform that can be implemented on a digital computer. However, such a difficulty is avoided in the proposed approach since it uses the Laplace-domain image of the impulse response to obtain its time-domain representation. The numerical simulations presented in the thesis demonstrate that using the time-domain waveform of the impulse response, computed using the proposed approach and properly filtered with a Butterworth filter, guides the order selection algorithm to select a smaller order, i.e., the reduced system becomes more compact in size. The phrase "smaller or more compact" in this context refers to the comparison with existing techniques currently in use, which seek to generate some form of time-domain approximations for the impulse response through driving the original network with pulse-shaped function (e.g., Gaussian pulse).

This study examines the linkages between output growth and output volatility in the G7 countries over the period 1958M2-2013M8. Using the VAR-based spillover index approach by Diebold and Yilmaz (2012) we find that: i) output growth and volatility are highly intertwined; ii) spillovers have reached unprecedented levels during the global financial crisis; and iii) the US has been the largest transmitter of growth and volatility shocks. Generalized impulse response analyses suggest moderate growth spillovers and sizable volatility spillovers across countries. Cross-variable effects indicate that volatility shocks lead to lower growth, while growth shocks reduce output volatility.

Base teórica: A doença de Parkinson (DP) é a segunda enfermidade neurodegenerativa mais frequente, crescendo proporcionalmente com o aumento da idade. É uma doença de comprometimento motor e não motor. Levodopa e agonistas dopaminérgicos (AD) são usados no tratamento da DP, permitindo um controle ótimo dos sintomas nos primeiros anos. Entretanto, em 5 anos, metade dos pacientes terão complicações motoras e nãomotoras induzidas pelo uso de antiparkinsonianos. Manifestações neuropsiquiátricas são frequentes, entre elas depressão, ansiedade, prejuízos cognitivos, sintomas psicóticos e transtorno de descontrole dos impulsos(DI). O DI é uma condição caracterizada pela falência em resistir a impulsos ou tentação de executar atos. O DI está associado ao uso de antiparkinsonianos, em especial, os agonistas dopaminérgicos A identificação desta condição é primordial para seu tratamento e estudo adequados. Na literatura atual, o questionário padrão-ouro foi validado na língua inglesa (QUIP), não existindo uma validação para língua portuguesa. Objetivo: Traduzir e validar o questionário QUIP-CS, em sua versão curta e aplicável no momento presente da DP, para lingua Portuguesa do Brasil Métodos: A versão curta da QUIP (QUIP-CS) foi traduzida para o Português por tradutor juramentado. Após, esta foi avaliada por 5 especialistas em DP no Brasil, sendo sugeridas pequenas correções. A versão corrigida em português foi retrotraduzida para o inglês por 2 tradutores juramentados nativos na língua original da escala (inglês), que compararam suas versões posteriormente, chegando-se a uma nova versão final neste idioma. Esta foi enviada ao autor da escala original, que concordou com esta versão, ou seja, foram mantidas as propriedades semânticas do instrumento. Após, a versão final em Português foi auto-aplicada em 65 indivíduos com diagnóstico de DP em tratamento no ambulatório especializado no HCPA, sendo que, de forma aleatória, para 30 foi aplicado um questionário de avaliação sobre o grau de dificuldade de compreensão de suas perguntas. Resultados: Em uma escala de 1 a 5 pontos, onde 1 era nenhuma compreensão das perguntas e 5, clara compreensão, a média de entendimento pelos pacientes foi de 4,06 +/- 0,69 DP. Conclusão: A avaliação desta versão foi considerada de fácil compreensão pelos próprios pacientes. O artigo para validação da tradução do conteúdo da versão em Português da QUIP-CS está em fase de revisão para publicação. / Background: Parkinson’s disease (PD) is the second most often neurodegenerative disease and proportionally growing with people aging. PD is a disease with motor and nonmotor clinical features. Levodopa and dopaminergic agonists (DA) are used for PD treatment, allowing an exquisite control of the motor symptoms during the first years. However, in five years, half patients will present motor or non-motor complications induced by cronic use of these medications. Neuropsychiatric symptoms are often, for example, depression, anxiety, cognitive impairment, psychotic symptoms and impulse control disorders (ICD). The ICD is characterized by failure on resisting an impulse or on performing an specific act. Identification of the PD affected patients is crucial for proper management and study of this condition. There is an already validated self-reported questionnaire for this purpose, the Parkinson's Disease Impulsive-Compulsive Disorders Questionnaire (QUIP), without equivalent in portuguese language. Objective: To translate and to validate the Portuguese short version of the gold-standard questionnaire for identifying ICDs PD affected patients, applicable at the current moment of PD Methods: QUIP-CS was first translated to Portuguese by a professional translator. This translated version was shown to 5 PD neurologist specialists. in Brazil, being suggested minor modifications on it. This new Portuguese revised version was back translated to English by two independent native English speakers. They were both asked to compare the version one another and checked for differences. Then, they contacted each other and got a final back translated version. This one was sent for the original author, that approved its new version comparing to his original and validated one, with no loss of it’s original properties. The Portuguese corrected version was applied to 65 patients in a random way at PD’s ambulatory at HCPA. From these, 30 were asked to answer a number that would represent their level of QUIP-CS questions’ comprehension. Results: In a 1 to 5 point scale, being 1 no comprehension and 5, total comprehension, the average was 4,06 +/- 0,69 DP. Conclusion: Our results on Portuguese version of QUIP-CS show that QUIP-CS translated and corrected version was easily understood and easily self-applied. The article is under revision to be submitted for publication.