831 |
Imperfect Channel Knowledge for Interference AvoidanceLajevardi, Saina Unknown Date
No description available.
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832 |
Integrable Couplings of the Kaup-Newell Soliton HierarchyZhang, Mengshu 01 January 2012 (has links)
By enlarging the spatial and temporal spectral problems within a certain Lie algebra, a hierarchy of integrable couplings of the Kaup-Newell soliton equations is constructed. The recursion operator of the resulting hierarchy of integrable couplings is explicitly computed. The integrability of the new coupling hierarchy is exhibited by showing the existence of infinitely many commuting symmetries.
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833 |
Prediction Model to Estimate the Zero Crossing Point for Faulted WaveformsHossan, Md. Shakawat 01 January 2014 (has links)
In any power system, fault means abnormal flow of current. Insulation breakdown is the cause of fault generation. Different factors can cause the breakdown: Wires drifting together in the wind, Lightning ionizing air, wires with contacts of animals and plants, Salt spray or pollution on insulators. The common type of faults on a three phase system are single line-to-ground (SLG), Line-to-line faults (LL), double line-to-ground (DLG) faults, and balanced three phase faults. And these faults can be symmetrical (balanced) or Unsymmetrical (imbalanced).In this Study, a technique to predict the zero crossing point has been discussed and simulated. Zero crossing point prediction for reliable transmission and distribution plays a significant role. Electrical power control switching works in zero crossing point when a fault occurs. The precision of measuring zero crossing point for syncing power system control and instrumentation requires a thoughtful approach to minimize noise and external signals from the corrupted waveforms A faulted current waveform with estimated faulted phase/s, the technique is capable of identifying the time of zero crossing point. Proper Simulation has been organized on MATLAB R2012a.
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834 |
Developing a Method to Study Ground State Properties of Hydrogen ClustersSchmidt, Matthew D.G. 02 September 2014 (has links)
This thesis presents the benchmarking and development of a method to study ground state properties of hydrogen clusters using molecular dynamics. Benchmark studies are performed on our Path Integral Molecular Dynamics code using the Langevin equation for finite temperature studies and our Langevin equation Path Integral Ground State code to study systems in the zero-temperature limit when all particles occupy their nuclear ground state. A simulation is run on the first 'real' system using this method, a parahydrogen molecule interacting with a fixed water molecule using a trivial unity trial wavefunction. We further develop a systematic method of optimizing the necessary parameters required for our ground state simulations and introduce more complex trial wavefunctions to study parahydrogen clusters and their isotopologues orthodeuterium and paratritium. The effect of energy convergence with parameters is observed using the trivial unity trial wavefunction, a Jastrow-type wavefunction that represents a liquid-like system, and a normal mode wavefunction that represents a solid-like system. Using a unity wavefunction gives slower energy convergence and is inefficient compared to the other two. Using the Lindemann criterion, the normal mode wavefunction acting on floppy systems introduces an ergodicity problem in our simulation, while the Jastrow does not. However, even for the most solid-like clusters, the Jastrow and the normal mode wavefunctions are equally efficient, therefore we choose the Jastrow trial wavefunction to look at properties of a range of cluster sizes. The energetic and structural properties obtained for parahydrogen and orthodeuterium clusters are consistent with previous studies, but to our knowledge, we may be the first to predict these properties for neutral paratritium clusters. The results of our ground state simulations of parahydrogen clusters, namely the distribution of pair distances, are used to calculate Raman vibrational shifts and compare to experiment. We investigate the accuracy of four interaction potentials over a range of cluster sizes and determine that, for the most part, the ab initio derived interaction potentials predict shifts more accurately than the empirically based potentials for cluster sizes smaller than the first solvation shell and the trend is reversed as the cluster size increases. This work can serve as a guide to simulate any system in the nuclear ground state using any trial wavefunction, in addition to providing several applications in using this ground state method.
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835 |
Zombie Banks and Forbearance Lending: Causes, Effects, and Policy MeasuresWillam, Daniel 28 January 2015 (has links) (PDF)
Zombie banks are banks that are practically insolvent but continue to exist through hiding bad loans on their balance sheet. This can be achieved by rolling over bad loans instead of writing them off, a process known as forbearance lending, zombie lending or evergreening.
Zombie banks have received increased attention of late, not least because of the sovereign debt and banking crisis in Europe. This follows other banking crises in the US and Japan which have equally seen an increased number of bank failures, and where insolvent companies have been kept alive by banks.
This study aims to give a theoretical assessment of the phenomenon around zombie banks and forbearance lending. Although zombie banks are the focus of a wide public debate, the existing research has not been able to fully explain many aspects around them, such as the several motives for forbearance lending, the impact of forbearance lending on the overall portfolio of zombie banks, or the right policy response in dealing with them. In light of this, the study presents three models that simulate the behavior of banks when rolling over bad loans. These models offer insights into the causes and effects of zombie banking, and also allow us to analyze the context of policy measures by the government and the central bank. To put the models into the right context, the study also provides a detailed overview of the theoretical and empirical literature as well as the practical experience with zombie banks and forbearance lending in Japan and Europe.
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836 |
A Rational Exergy Management Model to Curb CO2 Emissions in the Exergy-Aware Built Environments of the FutureKilkis, Siir January 2011 (has links)
This thesis puts forth the means of a strategic approach to address a persistent problem in the energy system and in this way, to transition the built environment to a future state that is more exergy-aware to curb CO2 emissions. Such a vision is made possible by the six-fold contributions of the research work: I) An analytical model is developed, which for the first time, formulates the CO2 emissions that are compounded in the energy system as a function of the systematic failures to match the supply and demand of exergy. This model is namely the Rational Exergy Management Model or REMM. II) REMM is then applied to analyze the pathways in which it is possible to lead the built environment into addressing structural overshoots in its exergy supply to curb CO2 emissions. The cases that embody these pathways are also analyzed over a base case, including cases for sustainable heating and cooling. III) New tools are designed to augment decision-making and exemplify a paradigm shift in the more rational usage of exergy to curb CO2 emissions. These include a scenario-based analysis tool, new options for CO2 wedges, and a multi-fold solution space for CO2 mitigation strategies based on REMM. IV) The concept of a net-zero exergy building (NZEXB) is developed and related to REMM strategies as the building block of an exergy-aware energy system. The target of a NZEXB is further supported by key design principles, which address shortcomings in state-of-the-art net-zero design. V) A premier building that deployed the key design principles to integrate building technology in an innovative, exergy-aware design and received LEED Platinum is analyzed on the basis of the NZEXB target. The results validate that this building boosts net self-sufficiency and curbs compound CO2 emissions, which are then presented in a proposed scheme to benchmark and/or label future NZEXBs. VI) Based on the scalability of the best-practices of the NZEXB ready building, the means to realize a smarter energy system that has exergy-aware relations in each aspect of the value chain to curb CO2 emissions are discussed. This includes a target for such a network at the community level, namely a net-zero exergy community (NZEXC). As a whole, the results of the thesis indicate that the strategic approach as provided by REMM and the NZEXB target of the research work has the potential to steer the speed and direction of societal action to curb CO2 emissions. The thesis concludes with a roadmap that represents a cyclical series of actions that may be scaled-up at various levels of the built environment in a transition to be in better balance with the Planet. / QC 20111014
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837 |
A Numerical Investigation Of A Two-Stroke Poppet-Valved Diesel Engine ConceptTeakle, Philip Robert January 2004 (has links)
Two-stroke poppet-valved engines may combine the high power density of two - stroke engines and the low emissions of poppet-valved engines. A two-stroke diesel engine can generate the same power as a four-stroke engine of the same size, but at higher (leaner) air/fuel ratios. Diesel combustion at high air/fuel ratios generally means hydrocarbons, soot and carbon monoxide are oxidised more completely to water and carbon dioxide in the cylinder, and the opportunity to increase the rate of exhaust gas recirculation should reduce the formation of nitrogen oxides (NOx). The concept is being explored as a means of economically modifying diesel engines to make them cleaner and/or more powerful. This study details the application of two computational models to this problem. The first model is a relatively simple thermodynamic model created by the author capable of rapidly estimating the behaviour of entire engine systems. It was used to estimate near-optimum engine system parameters at single engine operating points and over a six-mode engine cycle. The second model is a detailed CFD model called KIVA-ERC. It is a hybrid of the KIVA engine modelling package developed at the Los Alamos National Laboratory and combustion and emissions subroutines developed at the University of Wisconsin-Madison Engine Research Center. It was used for detailed scavenging and combustion simulations and to provide estimates of emissions levels. Both models were calibrated and validated for four-stroke cycle operation using experimental data. The thermodynamic model was used to provide initial and boundary conditions to the KIVA-ERC model. Conversely, the combustion simulations were used to adjust zero-dimensional combustion correlations when experimental data was not available. Scavenging simulations were performed with shrouded and unshrouded intake valves. A new two-zone scavenging model was proposed and validated using multidimensional scavenging simulations. A method for predicting the behaviour of the two-stroke engine system based on four-stroke data has been proposed. The results using this method indicate that a four-stroke diesel engine with minor modifications can be converted to a two-stroke cycle and achieve substantially the same fuel efficiency as the original engine. However, emissions levels can not be predicted accurately without experimental data from a physical prototype. It is therefore recommended that such a prototype be constructed, based on design parameters obtained from the numerical models used in this study.
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838 |
On the zero-point energy of elliptic-cyliindrical and spheroidal boundaries : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Theoretical Physics at Massey University, New ZealandKitson, Adrian Robert January 2009 (has links)
Zero-point energy is the energy of the vacuum. Disturbing the vacuum results in a change in the zero-point energy. In 1948, Casimir considered the change in the zeropoint energy when the vacuumis disturbed by two parallelmetal plates. The plates disturb the vacuum by restricting the quantum fluctuations of the electromagnetic field. Casimir found that the change in the zero-point energy implies that the plates are attracted to each other. With the recent advances made in the experimental verification of this remarkable result, theoretical interest has been rekindled. In addition to the original parallel plate configuration, several other boundaries have been studied. In this thesis, two novel boundaries are considered: elliptic-cylindrical and spheroidal. The results for these boundaries lead to the conjecture that zero-point energy does not change for small deformations of the boundary that preserve volume. Assuming the conjecture, it is shown that zero-point energy plays a stabilizing role in quantum chromodynamics, the leading theory of the strong interaction.
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839 |
Initial capital and margins required to secure a Japanese life insurance policy portfolio under stochastic interest ratesSato, Manabu Unknown Date (has links) (PDF)
During the last decade several Japanese life insurance companies failed mainly due to interest losses. In fact, interest rate risk dominates mortality risk for a portfolio of business in force. When the interest rates are modelled as random variables, the yields on bonds are the sum of expected short spot rates and a risk premium for random bond prices. However, in our study, we assume a risk-neutral environment, i.e. zero risk premiums. As tools to deal with stochastic interest rates, various interest rate term structure models are considered. The Vasicek model, the Heath-Jarrow-Morton (hereafter “HJM”) approach and Cairns’ model are explained in detail. The history and nature of the very low interest rate environment in Japan is described in line with the monetary policy framework of the central bank. An unusual interest rate movement in the very low interest rate environment is identified. A modified HJM approach and Cairns’ model are chosen in our study. Cairns’ model is used to graduate the initial yield curve. The HJM approach with a specific volatility function and modified to deal with very low interest rates is used for simulating subsequent developments of the initial yield curve. After the introduction of various concepts needed to investigate a life insurance policy portfolio, we prepare for simulation by collecting information and by fitting parameters to market observations. The Yen swap curve is chosen as a base yield curve. The simulation results show how much initial capital and/or margins are needed in order to avoid the ruin of a portfolio.
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840 |
Nolltolerans i skolan om hot och våld : En studie om rektorers tolkning av begreppet nolltoleransLöfving, David, Petersson, Joakim January 2009 (has links)
<p> </p><p>Arbetets art: Examensarbete i lärarutbildningen, Avancerad nivå, 15 hp</p><p>Högskolan i Skövde</p><p>Titel: Nolltolerans i skolan om hot och våld - En studie om rektorers tolkning av</p><p>begreppet nolltolerans</p><p>Sidantal: 41</p><p>Författare: David Löfving och Joakim Petersson</p><p>Handledare: Kennert Orlenius</p><p>Datum: januari, 2009</p><p>Nyckelord: nolltolerans, hot och våld, åtgärder, gränsdragning, agerande</p><p>I USA på 1990-talet infördes en lag gällande nolltolerans mot vapen i skolan. Denna lag</p><p>har fått en vidare tolkning vilket har gjort att många elever har blivit exkluderade från</p><p>undervisningen av märkliga skäl.</p><p>Uppsatsen handlar om rektorers syn på begreppet nolltolerans i frågor om hot och våld</p><p>mot skolpersonal. Vidare redogör studien för hur rektorer arbetar förebyggande och hur</p><p>deras efterarbete ser ut. Dessutom berör studien rektorers erfarenheter kring hot och</p><p>våld mot skolpersonal. För att nå fram till studiens syfte så intervjuades rektorer på</p><p>högstadieskolor.</p><p>De intervjuade rektorerna hade inga större erfarenheter kring hot och våld mot</p><p>skolpersonal. Rektorerna är positivt inställda till nolltoleransbegreppet dock så ser de en</p><p>viss svårighet till att införa ett sådant begrepp. Allting handlar om gränsdragningar, var</p><p>går gränsen för hot och våld? Rektorerna ger också uttryck för det förebyggande arbetet</p><p>i undervisningen. Det finns handlingsplaner på samtliga av de intervjuade rektorernas</p><p>arbetsplatser som både tar upp förebyggande och efterföljande arbete kring hot och</p><p>våld.</p><p> </p>
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