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Information Diffusion and Safe Havens : Multi-scale Network Dynamics in the Biotech MarketsYoussef, Lovisa, Zelic, Tijana January 2019 (has links)
This paper analyzes the return connectedness between the biotechnology sector and other financial assets for 1 January 2000 to 31 December 2018, using an empirical approach from both time- and frequency-domain. The results reveal that the connectedness between the biotechnology sector and other financial assets are decreasing with time, entailing high diversification opportunities in the long-run. Our results also suggest that the spillover effect from the biotechnology sector is higher than the spillover effect to the biotechnology sector, proposing that the sector affects other financial assets to a greater extent than they affect the biotechnology sector. Concurrently, we found that the net directional connectedness is negative for the sector, which means that it does not transmit shocks to others since it is not subject to significant return or volatility shocks. This implies that the systematic risk connected to the biotechnology sector is lower than previous studies argue for. Thus, our main finding is that investments in the sector has safe haven properties, indicating that they are independent towards other sectors. By investing in the biotechnology sector, investors contribute to society and supports the R&D, leading to development of vital drugs. In light of this, we argue that investments in the sector are socially beneficial. Building on these insights, investments in the biotechnology sector are of importance when investing in a prosperous world.
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Study of Global Power System Frequency Behavior Based on Simulations and FNET MeasurementsTsai, Shu-Jen Steven 22 July 2005 (has links)
A global view of power system's frequency opens up a new window to the "world" of large system's dynamics. With the aid of global positioning system (GPS), measurements from different locations can be time-synchronized; therefore, a system-wide observation and analysis would be possible. As part of the U.S. nation-wide power frequency monitoring network project (FNET), the first part of the study focuses on utilizing system simulation as a tool to assess the frequency measurement accuracy needed to observe frequency oscillations from events such as remote generation drops in three U.S. power systems. Electromechanical wave propagation phenomena during system disturbances, such as generation trip, load rejection and line opening, have been observed and discussed. Further uniform system models are developed to investigate the detailed behaviors of wave propagation. Visualization tool is developed to help to view frequency behavior simulations. Frequency replay from simulation data provides some insights of how these frequency electromechanical waves propagate when major events occur. The speeds of electromechanical wave propagation in different areas of the U.S. systems, as well as the uniform models were estimated and their characteristics were discussed. Theoretical derivation between the generator's mechanical powers and bus frequencies is provided and the delayed frequency response is illustrated.
Field-measured frequency data from FNET are also examined. Outlier removal and wavelet-based denoising signal processing techniques are applied to filter out spikes and noises from measured frequency data. System's frequency statistics of three major U.S. power grids are investigated. Comparison between the data from phasor measurement unit (PMU) at a high voltage substation and from FNET taken from 110 V outlets at distribution level illustrates the close tracking between the two. Several generator trip events in the Eastern Interconnection System and the Western Electricity Coordinating Council system are recorded and the frequency patterns are analyzed. Our trigger program can detect noticeable frequency drop or rise and sample results are shown in a 13 month period. In addition to transient states' observation, the quasi-steady-state, such as oscillations, can also be observed by FNET. Several potential applications of FNET in the areas of monitoring & analysis, system control, model validation, and others are discussed. Some applications of FNET are still beyond our imagination. / Ph. D.
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Spatial Scaling of Large-Scale Circulations and Heat Transport in Turbulent Mixed ConvectionWesthoff, Andreas 14 November 2012 (has links)
No description available.
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New Insights into the Spinal Recurrent Inhibitory Pathway Normally and After Motoneuron RegenerationObeidat, Ahmed Zayed 29 May 2013 (has links)
No description available.
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Dinâmica em freqüência de lasers semicondutores sob realimentação ótica ortogonal e aplicação: chaveamento todo-ótico em frequênciaSorrentino, Taciano Amaral 30 June 2010 (has links)
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Previous issue date: 2010-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / We analyze the dynamics of semiconductor lasers radiation frequency when these
lasers are subject to different conditions of optical feedback, and we demonstrate
how it is possible to control the emission frequency using the different configurations
explored. In the first system studied a semiconductor laser is fed back with light
which polarization is orthogonal to the output polarization, spectrally filtered by
a cesium atomic vapor. This system, besides presenting an effective technique to
stabilize the laser frequency and reduce the laser linewidth, was the first to exhibit
frequency bistable and multistable optical regimes with amplitude practically constant.
This unique feature opens the way for applications in all-optical FM logical
devices. The bistable and multistable regimes are interpreted through a phenomenological
model, and, for the bistable regime, we discuss a rate equation model, built
taking in account thermal effects and gain saturation. We also present an all-optical
frequency switch, the first of his kind. The second system is used to investigate
the behavior of the emission frequency of a semiconductor laser with an external
cavity, inside which is placed an atomic filter. For different values of the injection
current we observe the laser frequency locking in the atomic line, bistability and
reproducible frequency instabilities. / Estudamos a dinâmica em frequência da radiação emitida por lasers semicondutores
submetidos a diferentes condições de realimentação ótica e demonstramos
como é possível o controle da frequência de emissão pelo uso das diferentes configurações exploradas. No primeiro sistema estudado, um laser semicondutor é realimentado
por luz com polarização ortogonal á de saída, filtrada espectralmente
por vapor atômico de césio. Além de apresentar uma técnica efetiva para estabilização da frequência laser e redução de largura de linha, esse foi o primeiro sistema
a exibir regimes de biestabilidade e multiestabilidade ótica exclusivamente em sua
frequência, ou seja, com amplitude constante. Essa característica única abre caminho
para aplicações desta técnica em dispositivos lógicos FM do tipo tudo ótico .
O aparecimento desses regimes é analizado através de um modelo fenomenológico e,
para o caso biestável, construímos também um modelo de equações de taxa, onde
levamos em conta efeitos térmicos e de saturação de ganho no laser semicondutor.
Como aplicação dessa técnica apresentamos o funcionamento de uma chave em
frequência do tipo tudo-ótico , a primeira deste gênero. O segundo sistema experimentalmente
investigado foi concebido para produzir um comportamento dinâmico
da frequência de um laser semicondutor com cavidade estendida quando um filtro
atômico é posicionado dentro dessa cavidade. Para diferentes valores da corrente de
injeção observamos o travamento da frequência laser na linha atômica, biestabilidade
e instabilidades não aleatórias.
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Dynamic Model Based Novel Findings in Power Systems Analysis and Frequency Measurement VerificationKook, Kyung Soo Soo 03 July 2007 (has links)
This study selects several new advanced topics in power systems, and verifies their usefulness using the simulation. In the study on ratio of the equivalent reactance and resistance of the bulk power systems, the simulation results give us the more correct value of X/R of the bulk power system, which can explain why the active power compensation is also important in voltage flicker mitigation. In the application study of the Energy Storage System(ESS) to the wind power, the new model implementation of the ESS connected to the wind power is proposed, and the control effect of ESS to the intermittency of the wind power is verified. Also this study conducts the intensive simulations for clarifying the behavior of the wide-area power system frequency as well as the possibility of the on-line instability detection.
In our POWER IT Laboratory, since 2003, the U.S. national frequency monitoring network (FNET) has been being continuously operated to monitor the wide-area power system frequency in the U.S. Using the measured frequency data, the event of the power system is triggered, and its location and scale are estimated. This study also looks for the possibility of using the simulation technologies to contribute the applications of FNET, finds similarity of the event detection orders between the frequency measurements and the simulations in the U.S. Eastern power grid, and develops the new methodology for estimating the event location based on the simulated N-1 contingencies using the frequency measurement.
It has been pointed out that the simulation results can not represent the actual response of the power systems due to the inevitable limit of modeling power systems and different operating conditions of the systems at every second. However, in the circumstances that we need to test such an important infrastructure supplying the electric energy without taking any risk of it, the software based simulation will be the best solution to verify the new technologies in power system engineering and, for doing this, new models and better application of the simulation should be proposed.
Conducting extensive simulation studies, this dissertation verified that the actual X/R ratio of the bulk power systems is much lower than what has been known as its typical value, showed the effectiveness of the ESS control to mitigate the intermittence of the wind power from the perspective of the power grid using the newly proposed simulation model of ESS connected to the wind power, and found many characteristics of the wide-area frequency wave propagation. Also the possibility of using the simulated responses of the power system for replacing the measured data could be confirmed and this is very promising to the future application of the simulation to the on-line analysis of the power systems based on the FNET measurements. / Ph. D.
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