Modelling International Bond Markets with Affine Term Structure Models

This paper investigates the performance of international affine term structure models (ATSMs) that are driven by a mutual set of global state variables. We discuss which mixture of Gaussian and square root processes is best suited for modelling international bond markets. We derive necessary conditions for the correlation and volatility structure of mixture models to accommodate various empirical stylized facts such as the forward premium puzzle and differently shaped yield curves. Using UK-US data we estimate international ATSMs taking into account the joint transition density of yields and exchange rates without assuming normality. We find strong empirical evidence for negatively correlated global factors in international bond markets. Further, the empirical results do not support the existence of local factors in the UK-US setting, suggesting that diversification benefits from holding currency- hedged bond portfolios in these markets are likely to be small. Altogether, we find that mixture models greatly enhance the performance of ATSMs.International affine term structure models, Estimation, Exchange rate, Model Selection

Das Portfolio als Lehr- und Lerninstrument im Deutschunterricht der BMHS

Die vorliegende Arbeit versucht, die Relevanz von konstruktivistisch orientiertem Unterricht am Beispiel des Portfolioinstruments im Deutschunterricht aufzuzeigen. Konstruktivistische Ansätze des Lernens kehren der Wissenseinflößung den Rücken und nehmen die Lerner/-innen als individuelle Subjekte in den Blick, die jeweils eine andere Perspektive auf das Lernen werfen. Die theoretischen Grundlagen der Arbeit nehmen das Portfolio als Weiterentwicklungsinstrument zu schon vorhandenen Lehr- und Lernformen und als Möglichkeit prozessorientierten Schreibens mit dem Fokus auf die Reflexion in den Blick sowie auch den Aspekt des individuellen und eigenverantwortlichen Lernens. Es wird vor allem die Veränderung der Lehr- und Lernkultur näher betrachtet, die durch die Berücksichtigung von selbstbestimmten, selbstgesteuerten und eigenverantwortlichen Aspekten sowohl den Lehrenden als auch den Lernenden eine andere Rolle abverlangt. Ein weiterer Abschnitt der Arbeit widmet sich dem kompetenzorientierten Unterricht mit Portfolios, der das schulische Schreiben unter der prozessorientierten Perspektive berücksichtigt, einzelne Schreibprozessmodelle abbildet und miteinander vergleicht. Die theoretischen Grundlagen sind die Basis für den empirischen Teil dieser Arbeit, dessen Kern die Reflexionen von Schüler/-innen der 11. Schulstufe (Handelsschule) bilden. Die Reflexionen der Lernenden werden herangezogen, um vier Forschungsfragen zu beantworten, die danach fragen, inwiefern die Lehr- und Lernkultur und die Individualität innerhalb der Portfolioarbeit wahrgenommen werden, ob diese Wahrnehmung zur Schreibmotivation beiträgt und ob durch reflexive Praxis metakognitives Denken ermöglicht wird.This thesis tries to demonstrate the relevance of constructivist-oriented teaching in German lessons on the example of the portfolio method. The constructivist view focus on a learning which considers individual subjects, who have a different perspective of learning. The theoretical foundations of this thesis notice the portfolio as a tool to further develop existing teaching and learning methods and process-oriented writing including the focus on the reflection and also the aspect of individual and autonomous learning. In more detail, especially the change in teaching and learning culture that demanded by the inclusion of self-determined, self-directed and autonomous aspects a different role of the teachers and learners is considered. Another part is devoted to the competency-based teaching with portfolios, which involves writing under the process-oriented perspective. Further individual writing process models will be imaged and compared with each other. The theoretical principles are the basis for the empirical part of this thesis. The reflections from the students of the 11th school level (commercial school) will be analyzed in this part. They are used to answer four research questions that ask how the teaching and learning culture and individuality are perceived within the portfolio of work, whether this contributes to the writing motivation and whether through reflective practice metacognitive thinking becomes possible

Experimental study of the relationship between injection rate shape and Diesel ignition using a novel piezo-actuated direct-acting injector

Injection rate shaping is one of the most attractive alternatives to multiple injection strategies; however, its implementation has been for long time impeded by limitations in the injector technology and therefore, the experimental information available in the literature about this topic is lacking. In this work, a novel prototype common-rail injector featuring direct control of the nozzle needle by means of a piezo-stack (direct-acting) allowed a fully flexible control on the nozzle needle movement and enabled the implementation of alternative injection rate shapes typologies. This state of the art injector, fitted with a 7-hole nozzle, was tested at real engine conditions studying the spatial-temporal evolution of CH* and OH* chemiluminescence intensity produced by the fuel combustion. A wide test matrix was performed in an optically accessible hot-spray test rig to understand the influence that partial needle lift and alternative injection rate shapes have on the Diesel ignition The results showed that alternative injection rate profiles have a substantial impact on the ignition event affecting the premixed phase of the combustion and the location where the ignition takes place. Moreover, the results proved that the modifications in the internal flow caused by the partial needle lift are reflected on the ignition timing: although partial needle lift and injection pressure have similar effects on the mass flow rate, in the first case, the ignition delay is reduced, while in the second, the combustion is delayed as a consequence of a different spray development.This work was sponsored by General Motors R&D, Warren, MI. The authors would like to thank Jose Enrique del Rey, Moises Ferrandez Hermosilla and Juan Pablo Viera for their precious help in the laboratory during the tests.Macian Martinez, V.; Payri Marín, R.; Ruiz Rosales, S.; Bardi, M.; Plazas, AH. (2014). Experimental study of the relationship between injection rate shape and Diesel ignition using a novel piezo-actuated direct-acting injector. Applied Energy. 118:100-113. doi:10.1016/j.apenergy.2013.12.025S10011311

Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines.

Alkali metal atoms show an intense natural fluorescence in the burned gas region of internal combustion engines. This fluorescence offers great opportunity for spectroscopic combustion analysis in internal combustion engines without the requirement of laser excitation or image intensifiers. To quantify this fluorescence intensity, spectroscopic and thermodynamic properties of the alkali metals lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) and their oxidation products and ions were analyzed. Collisional energy transfer and reabsorption effects (including temperature- and pressure dependent lineshapes) were calculated over the range of engine environments. Three compounds containing Li, Na and K, respectively, were selected as fuel additives for engine experiments. The experiments were conducted on an optical, single cylinder, spark-ignition, direct-injection research engine, and the fluorescence of the three alkali components was recorded simultaneously using three CMOS high-speed cameras. The two-component fluorescence intensity ratios (Na/K, Li/K and Na/Li) are shown to depend on temperature, pressure and equivalence ratio. However, the three-component ratio Na•Li/K2 is nearly independent of pressure and equivalence ratio in the tested range of operating conditions and can serve as a direct marker for burned gas temperature. Subsequently, equivalence ratio can be determined from any of the bi-component fluorescence ratios. The spatially integrated fluorescence intensity of the single components is a function of burned gas temperature, cylinder pressure, equivalence ratio and mass fraction of burned fuel. When temperature and equivalence ratio are determined from the fluorescence intensity ratios, the spatially integrated fluorescence signal of sodium can serve as a marker for the mass fraction of burned fuel. The tool was applied to various cases of direct injected, stratified engine combustion to illustrate the potential of this technique for optimization of the combustion strategy and engine hardware configuration.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/97841/1/mosb_1.pd

Single Laser Detection of CO and OH via Laser Induced Fluorescence

Two-photon laser-induced fluorescence detection of carbon monoxide with excitation in the Fourth Positive System near 280 nm is demonstrated in carbon monoxide/nitrogen mixtures at ambient conditions and in a methane/air Bunsen flame. Fully resolved rotational spectra are presented for the A–X (5,0) and (4,0) bands near 279 and 284 nm, respectively. Energy transfer from excited molecular nitrogen to carbon monoxide with subsequent fluorescence from carbon monoxide that was reported for low pressure conditions in the literature has also been observed at atmospheric conditions. It was further demonstrated that overlaps of some CO A–X (4,0) rotational lines with OH A–X (1,0) rotational lines allow simultaneous excitation of both species with a single laser. The fluorescence bands are completely separated, enabling detection without crosstalk. Detection limits are adequate to detect CO in nascent state in a flame and it is expected that for application in high-pressure, low-temperature combustion environments, where high quantities of CO are present, this approach can provide advantages compared to the excitation of CO at shorter wavelengths due to decreased laser beam attenuation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86784/1/Sick6.pd