We have developed a new cluster parallel graphics architecture that improves upon prior cluster parallel graphics systems for high performance supergraphics – the Vortex deferred sort-last parallel graphics architecture based on global Zspace paradigm. The new architecture bypasses limitations of screen-space based parallelization paradigms, solves known Z-space parallelization inefficiencies and problems. Vortex addresses the lack of global Z buffer awareness between GPUs and prevents artifacts in globally order-dependent blending on multiple GPUs. The new paradigm allows for full 1-1 process-GPU coupling with minimal interprocess and inter-GPU communications. This allows for maximal input bandwidth, maximal GPU utilization levels, near optimal load balances, and improved efficiency when scaled to larger configurations. The Vortex architecture introduces the new deferred sort-blend approach for preventing visual artefacts in globally order-dependent fragment blends. All blend fragments are buffered in an external sort-blend subsystem until the end of rendering, when they are Z-culled, sorted and blended into the final frame. The new approach allows for efficient automatic order-independent blending and results in frames without any global blending artifacts The new architecture gives us the ability to fully harness the processing power of state of art GPUs, and at the same time it offers a much easier parallelization paradigm to programmers, compared to existing screen-space CPGS parallelization paradigms. / Doctor of Philosophy (PhD)

This Thesis is composed by three independent papers that investigate central debates in empirical macroeconomic modeling. Chapter 1, entitled “A Model for Real-Time Data Assessment with an Application to GDP Growth Rates”, provides a model for the data revisions of macroeconomic variables that distinguishes between rational expectation updates and noise corrections. Thus, the model encompasses the two polar views regarding the publication process of statistical agencies: noise versus news. Most of the studies previous studies that analyze data revisions are based on the classical noise and news regression approach introduced by Mankiew, Runkle and Shapiro (1984). The problem is that the statistical tests available do not formulate both extreme hypotheses as collectively exhaustive, as recognized by Aruoba (2008). That is, it would be possible to reject or accept both of them simultaneously. In turn, the model for the DPP presented here allows for the simultaneous presence of both noise and news. While the “regression approach” followed by Faust et al. (2005), along the lines of Mankiew et al. (1984), identifies noise in the preliminary figures, it is not possible for them to quantify it, as done by our model. The second and third chapters acknowledge the possibility that macroeconomic data is measured with errors, but the approach followed to model the missmeasurement is extremely stylized and does not capture the complexity of the revision process that we describe in the first chapter. Chapter 2, entitled “Revisiting the Success of the RBC model”, proposes the use of dynamic factor models as an alternative to the VAR based tools for the empirical validation of dynamic stochastic general equilibrium (DSGE) theories. Along the lines of Giannone et al. (2006), we use the state-space parameterisation of the factor models proposed by Forni et al. (2007) as a competitive benchmark that is able to capture weak statistical restrictions that DSGE models impose on the data. Our empirical illustration compares the out-of-sample forecasting performance of a simple RBC model augmented with a serially correlated noise component against several specifications belonging to classes of dynamic factor and VAR models. Although the performance of the RBC model is comparable to that of the reduced form models, a formal test of predictive accuracy reveals that the weak restrictions are more useful at forecasting than the strong behavioral assumptions imposed by the microfoundations in the model economy. The last chapter, “What are Shocks Capturing in DSGE modeling”, contributes to current debates on the use and interpretation of larger DSGE models. Recent tendency in academic work and at central banks is to develop and estimate large DSGE models for policy analysis and forecasting. These models typically have many shocks (e.g. Smets and Wouters, 2003 and Adolfson, Laseen, Linde and Villani, 2005). On the other hand, empirical studies point out that few large shocks are sufficient to capture the covariance structure of macro data (Giannone, Reichlin and Sala, 2005, Uhlig, 2004). In this Chapter, we propose to reconcile both views by considering an alternative DSGE estimation approach which models explicitly the statistical agency along the lines of Sargent (1989). This enables us to distinguish whether the exogenous shocks in DSGE modeling are structural or instead serve the purpose of fitting the data in presence of misspecification and measurement problems. When applied to the original Smets and Wouters (2007) model, we find that the explanatory power of the structural shocks decreases at high frequencies. This allows us to back out a smoother measure of the natural output gap than that resulting from the original specification.

Thesis (D. Engr.)--Technische Universität München. / At head of title: Deutsche Geodätische Kommission bei der Bayerischend Akademie der Wissenschaften.

Thesis (M.S. in Information Technology Management and M.S. in Computer Science)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Burt Lundy. Includes bibliographical references (p. 99-100). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 328-349). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Bert Lundy, Wen Su. Includes bibliographical references (p. 101-103). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 116-120). Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 1974. / Mimeographed.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy

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