Results 1  10
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52
Filling Algorithms and Analyses for Layout Density Control
 IEEE Trans. ComputerAided Design
, 1999
"... In very deepsubmicron VLSI, manufacturing steps involving chemicalmechanical polishing (CMP) have varying e ects on device and interconnect features, depending on local characteristics of the layout. To reduce manufacturing variation due to CMP and to improve performance predictability and yield, ..."
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Cited by 26 (14 self)
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In very deepsubmicron VLSI, manufacturing steps involving chemicalmechanical polishing (CMP) have varying e ects on device and interconnect features, depending on local characteristics of the layout. To reduce manufacturing variation due to CMP and to improve performance predictability and yield, layout must be made uniform with respect to certain density criteria, by inserting \ ll &quot; geometries into the layout. To date, only foundries and special mask data processing tools perform layout postprocessing for density control. In the future, better convergence of performance veri cation ows will depend on such layout manipulations being embedded within the layout synthesis (placeandroute) ow. In this paper, we give the rst realistic formulation of the lling problem that arises in layout optimization for manufacturability. Our formulation seeks to add features to a given process layer, such that (i) feature area densities satisfy prescribed upper and lower bounds in all windows of given size, and (ii) the maximum variation of such densities over all possible window positions in the layout is minimized. We present e cient algorithms for density analysis, notably a multilevel approach that a ords usertunable accuracy. We also develop exact solutions to the problem of ll synthesis, based on a linear programming approach. These
Filling and Slotting : Analysis and Algorithms
 Proc. ACM/IEEE Intl. Symp. on Physical Design
, 1998
"... In very deepsubmicron VLSI, certain manufacturing steps  notably optical exposure, resist development and etch, chemical vapor deposition and chemicalmechanical polishing (CMP) have varying effects on device and interconnect features depending on local characteristics of the layout. To make th ..."
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Cited by 22 (15 self)
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In very deepsubmicron VLSI, certain manufacturing steps  notably optical exposure, resist development and etch, chemical vapor deposition and chemicalmechanical polishing (CMP) have varying effects on device and interconnect features depending on local characteristics of the layout. To make these effects uniform and predictable, the layout itself must be made uniform with respect to certain density parameters. Traditionally, only foundries have performed the postprocessing needed to achieve this uniformity, via insertion ("filling") or partial deletion ("slotting") of features in the layout. Today, however, physical design and verification tools cannot remain oblivious to such foundry postprocessing. Without an accurate estimate of the filling and slotting, RC extraction, delay calculation, and timing and noise analysis flows will all suffer from wild inaccuracies. Therefore, future placeand route tools must efficiently perform filling and slotting prior to performance analysi...
Liouville theorems and spectral edge behavior on abelian coverings of compact manifolds
"... Abstract. The paper describes relations between Liouville type theorems for solutions of a periodic elliptic equation (or a system) on an abelian cover of a compact Riemannian manifold and the structure of the dispersion relation for this equation at the edges of the spectrum. Here one says that the ..."
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Cited by 9 (5 self)
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Abstract. The paper describes relations between Liouville type theorems for solutions of a periodic elliptic equation (or a system) on an abelian cover of a compact Riemannian manifold and the structure of the dispersion relation for this equation at the edges of the spectrum. Here one says that the Liouville theorem holds if the space of solutions of any given polynomial growth is finite dimensional. The necessary and sufficient condition for a Liouville type theorem to hold is that the real Fermi surface of the elliptic operator consists of finitely many points (modulo the reciprocal lattice). Thus, such a theorem generically is expected to hold at the edges of the spectrum. The precise description of the spaces of polynomially growing solutions depends upon a ‘homogenized ’ constant coefficient operator determined by the analytic structure of the dispersion relation. In most cases, simple explicit formulas are found for the dimensions of the spaces of polynomially growing solutions in terms of the dispersion curves. The role of the base of the covering (in particular its dimension) is rather limited, while the deck group is of the most importance. The results are also established for overdetermined elliptic systems, which in particular leads to Liouville theorems for polynomially growing holomorphic functions on abelian coverings of compact analytic manifolds. Analogous theorems hold for abelian coverings of compact combinatorial or quantum graphs. 1.
HMMBased semantic Learning for a mobile robot
, 2004
"... We are developing a intelligent robot and attempting to teach it language. While there are many aspects of this research, for the purposes of this dissertation the most important are the following ideas. Language is primarily based on semantics, not syntax, which is the focus in speech recognition r ..."
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Cited by 8 (2 self)
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We are developing a intelligent robot and attempting to teach it language. While there are many aspects of this research, for the purposes of this dissertation the most important are the following ideas. Language is primarily based on semantics, not syntax, which is the focus in speech recognition research these days. To truly learn meaning, a language engine cannot simply be a computer program running on a desktop computer analyzing speech. It must be part of a more general, embodied intelligent system, one capable of using associative learning to form concepts from the perception of experiences in the world, and further capable of manipulating those concepts symbolically. This dissertation explores the use of hidden Markov models (HMMs) in this capacity. HMMs are capable of automatically learning and extracting the underlying structure of continuousvalued inputs and representing that structure in the states of the model. These states can then be treated as symbolic representations of the inputs. We show how a model consisting of a cascade of HMMs can be embedded in a small mobile robot and used to learn correlations among sensory inputs to create symbolic concepts, which can eventually be manipulated linguistically and used for decision making.
New and Exact Filling Algorithms for Layout Density Control
 Proc. IEEE Intl. Conf. on VLSI Design
, 1999
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Bayesian Selection of sign µ within mSUGRA in Global Fits Including WMAP5 Results
, 807
"... Abstract: We study the properties of the constrained minimal supersymmetric standard model (mSUGRA) by performing fits to updated indirect data, including the relic density of dark matter inferred from WMAP5. In order to find the extent to which µ < 0 is disfavoured compared to µ> 0, we compar ..."
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Cited by 7 (1 self)
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Abstract: We study the properties of the constrained minimal supersymmetric standard model (mSUGRA) by performing fits to updated indirect data, including the relic density of dark matter inferred from WMAP5. In order to find the extent to which µ < 0 is disfavoured compared to µ> 0, we compare the Bayesian evidence values for these models, which we obtain straightforwardly and with good precision from the recently developed multi–modal nested sampling (‘MultiNest’) technique. We find weak to moderate evidence for the µ> 0 branch of mSUGRA over µ < 0 and estimate the ratio of probabilities to be P(µ> 0)/P(µ < 0) = 6−61 depending on the prior measure and range used. There is thus positive (but not overwhelming) evidence that µ> 0 in mSUGRA. The MultiNest technique also delivers probability distributions of parameters and other relevant quantities such as superpartner masses. We explore the dependence of our results on the choice of the prior measure used. We also use the Bayesian evidence to quantify the consistency between the mSUGRA parameter inferences coming from the constraints that have the
EGRET Observations of the Extragalactic Gamma Ray Emission Astrophys
, 1998
"... The allsky survey in highenergy gamma rays (E>30 MeV) carried out by the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton GammaRay Observatory provides a unique opportunity to examine in detail the diffuse gammaray emission. The observed diffuse emission has a Galactic comp ..."
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Cited by 6 (0 self)
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The allsky survey in highenergy gamma rays (E>30 MeV) carried out by the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton GammaRay Observatory provides a unique opportunity to examine in detail the diffuse gammaray emission. The observed diffuse emission has a Galactic component arising from cosmicray interactions with the local interstellar gas and radiation as well an almost uniformly distributed component that is generally believed to originate outside the Galaxy. Through a careful study and removal of the Galactic diffuse emission, the flux, spectrum and uniformity of the extragalactic emission is deduced. The analysis indicates that the extragalactic emission is well described by a power law photon spectrum with an index of –(2.10±0.03) in the 30 MeV to 100 GeV energy range. No large scale spatial anisotropy or changes in the energy spectrum are observed in the deduced extragalactic emission. The most likely explanation for the origin of this extragalactic highenergy gammaray emission is that it arises primarily from unresolved gammarayemitting blazars. – 3 – 1.
The cohomology of the Steenrod algebra and representations of the general linear groups
 Trans. Amer. Math. Soc
"... ABSTRACT. Let Trk be the algebraic transfer that maps from the coinvariants of certain GLkrepresentation to the cohomology of the Steenrod algebra. This transfer was defined by W. Singer as an algebraic version of the geometrical transfer trk: n~((BVk)+)7 11'~(8°). It has been shown that the ..."
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Cited by 5 (1 self)
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ABSTRACT. Let Trk be the algebraic transfer that maps from the coinvariants of certain GLkrepresentation to the cohomology of the Steenrod algebra. This transfer was defined by W. Singer as an algebraic version of the geometrical transfer trk: n~((BVk)+)7 11'~(8°). It has been shown that the algebraic transfer is highly nontrivial, more precisely, that Trk is an isomorphism for k = 1, 2, 3 and that Tr = ffikTrk is a homomorphism of algebras. In this paper, we first recognize the phenomenon that if we start from any degree d, and apply Sq0 repeatedly at most (k 2) times, then we get into the region, in which all the iterated squaring operations are isomorphisms on the coinvariants of the GLkrepresentation. As a consequence, every finite Sq0family in the coinvariants has at most (k 2) non zero elements. Two applications are exploited. The first main theorem is that Trk is not an isomorphism for k 2: 5. Furthermore, Trk is not an isomorphism in infinitely many degrees for each k> 5. We also show that if Tre detects a nonzero element in certain de
Computation of TwoPhase Mixing Properties in RayleighTaylor Instability
 Representation and Processing of Spatial Expressions
, 1998
"... The statistical evolution of a planar, randomly perturbed fluid interface subject to RayleighTaylor instability is explored through numerical simulation in two space dimensions. The data set, generated by the fronttracking code FronTier, is highly resolved and covers a large ensemble of initial pe ..."
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Cited by 4 (1 self)
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The statistical evolution of a planar, randomly perturbed fluid interface subject to RayleighTaylor instability is explored through numerical simulation in two space dimensions. The data set, generated by the fronttracking code FronTier, is highly resolved and covers a large ensemble of initial perturbations. We closely approach a twofold convergence of the mean twophase flow: convergence of the numerical solution under computational mesh refinement, and statistical convergence under increasing ensemble size. Quantities that appear in the twophase averaged Euler equations are computed directly and analyzed for numerical and statistical convergence. Bulk averages show a high degree of convergence, whereas interfacial averages are convergent only in the outer portions of the mixing zone, which are comprised of coherent arrays of bubbles and mushrooming jets. Comparison with the familiar bubble/spike penetration law h = Agt 2 is complicated by the lack of scale invariance, inability to carry the simulations to late time, the increasing Mach numbers of the bubble/spike tips, and sensitivity to the method of data analysis. Finally, we use the simulation data to analyze some constitutive properties of turbulent mixing layers.
Zeroes of the Jones polynomial
 Phys. A
, 2001
"... We study the distribution of zeroes of the Jones polynomial VK(t) for a knot K. We have computed numerically the roots of the Jones polynomial for all prime knots with N ≤ 10 crossings, and found the zeroes scattered about the unit circle t  = 1 with the average distance to the circle approaching ..."
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Cited by 4 (0 self)
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We study the distribution of zeroes of the Jones polynomial VK(t) for a knot K. We have computed numerically the roots of the Jones polynomial for all prime knots with N ≤ 10 crossings, and found the zeroes scattered about the unit circle t  = 1 with the average distance to the circle approaching a nonzero value as N increases. For torus knots of the type (m,n) we show that all zeroes lie on the unit circle with a uniform density in the limit of either m or n → ∞, a fact confirmed by our numerical findings. We have also elucidated the relation connecting the Jones polynomial with the Potts model, and used this relation to derive the Jones polynomial for a repeating chain knot with 3n crossings for general n. It is found that zeroes of its Jones polynomial lie on three closed curves centered about the points 1,i and −i. In addition, there are two isolated zeroes located one each near the points t ± = e ±2πi/3 at a distance of the order of 3 −2/(n+2). Closedform expressions are deduced for the closed curves in the limit of n → ∞. 1