Business and life in space

The life support systems in the machine called the Space Shuttle is discussed and later about life support systems in a little cocoon that is far smaller than the shuttle; the more common term is a space suit

Baryonic Dark Halos: Machos and Cold Gas?

We consider the possibility that the dark matter in the halos of galaxies may be in the form of clusters of \macho s within which are embedded cold, dense gas clouds. Microlensing experiments have found evidence that the Galactic halo contains up to half of its mass in the form of low-mass \macho s. A number of observational and dynamical arguments point to the existence of hitherto unobserved cold gas around galaxies. We show that the cold gas can be stabilized by \macho\ clusters. Within the framework of a simple two-component model, we derive constraints on the \macho\ clusters and on the halo cold gas content. Typical cluster masses are \sim 10 \msun, typical \macho\ masses are \sim 0.01 \msun, and the gas content could be up to of order 50 \%. Various predictions are given for testing the hypothesis that such objects could constitute most of the mass in the dark halos of galaxies. If halos are indeed baryonic and contain significant amounts of cold gas, they are likely to play a much more active role in galaxy formation and evolution than is commonly supposed.Comment: 13 pages, submitted to ApJ. Uuencoded, gzip-compressed ps-file including 2 figures. Also available at http://www.astro.unibas.ch/~gerhard/papers/dmmn.ps.gz.u

Partitioning-based algorithm for pipelined scheduling and module assignment

We propose partitioning-based algorithms for pipeline scheduling, module assignment, and interconnect sharing. A novel hypergraph model is used to perform module assignment which facilitates the identification of sharable resources and the calculation of interconnect costs. The algorithms use clustering and interchange improvement techniques to maximize interconnect sharing. The results show significant improvement over other published results

Orthogonality and convergence of discrete Zernike polynomials

The Zernike polynomials are an infinite set of orthogonal polynomials over the unit disk, which are rotationally invariant. They are frequently utilized in optics, opthal- mology, and image recognition, among many other applications, to describe spherical aberrations and image features. Discretizing the continuous polynomials, however, introduces errors that corrupt the orthogonality. Minimizing these errors requires numerical considerations which have not been addressed. This work examines the orthonormal polynomials visually with the Gram matrix and computationally with the rank and condition number. The convergence of the Fourier-Zernike coe\ufb03cients and the Fourier-Zernike series are also examined using various measures of error. The orthogonality and convergence are studied over six grid types and resolutions, polynomial truncation order, and function smoothness. The analysis concludes with design criteria for computing an accurate analysis with the discrete Zernike polynomials

Syzygies of string modules for special biserial algebras

We present discrete models of special biserial (SB) algebras and their string modules, drawing inspiration from cellular automata, and cast new light on patterns among syzygies. We explore applications of our models to open questions in homological algebra regarding certain triangulated subcategories of derived categories, with implications for the finitistic dimension conjectures. More pertinently, our models provide the inner workings for a new, original GAP package called SBStrips, written and implemented by the author. Its source code is freely available online and its documentation is included as an appendix. The package calculates syzygies of string modules (and much more besides) using specialised methods much more efficient than the general methods currently employed by the \QPA\ package.Comment: vi+137 pages, 37 figures, single-spaced version of a PhD thesi

Synthesis from VHDL : Rockwell-counter case study

This report describes the design process and synthesis tools used in the UC Irvine CADLAB design environment to design a representative benchmark. The steps taken and rationale used in each stage of the design process are discussed. The benchmark is initially described using a VHDL behavioral description; results produced by each intermediate tool are presented, showing the system flow and integration of tools. The final silicon layout is performed in 3 micron CMOS technology