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Open Access Publications from the University of California

Scholarly Works (77 results)

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UCLA Previously Published Works (2005)

In this paper, we study an extended global routing problem with RLC crosstalk constraints. Considering simultaneous shield insertion and net ordering, we propose a multiphase algorithm to synthesize a global routing solution with track assignment to satisfy the RLC crosstalk constraint at each sink. The key algorithm phase is global routing synthesis with shield reservation and minimization based on prerouting shield estimation. Experiments using large industrial benchmarks show that compared to the best alternative with postrouting shield insertion and net ordering, the proposed algorithm with shield reservation and minimization reduces the congestion by 18.4 % with a smaller runtime. To the best of our knowledge, this is the first in-depth study on global routing synthesis with RLC crosstalk constraints.

    Cover page: Extended global routing with RLC crosstalk constraints
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    UCLA Previously Published Works (2004)

    Existing layout-optimization methods for both capacitive and inductive (RLC) crosstalk reduction assume a set of interconnects with a priori given crosstalk bounds in a routing region. RLC crosstalk budgeting is critical for effectively applying these methods at the full-chip level. In this paper, we formulate a full-chip routing optimization problem with RLC crosstalk budgeting, and solve this problem with a multiphase algorithm. In phase I, we solve an optimal RLC crosstalk budgeting based on linear programming to partition crosstalk bounds at sinks into bounds for net segments in routing regions. In phase II, we perform simultaneous shield insertion and net ordering to meet the partitioned crosstalk bounds in each region. In phase III, we carry out a local refinement procedure to reduce the total number of shields. Compared with the best alternative approach in experiments, the proposed algorithm reduces the total routing area by up to 5.71% and uses less runtime. To the best of our knowledge, this work is the first in-depth study on full-chip routing optimization with RLC crosstalk budgeting.

      Cover page: Full-chip routing optimization with RLC crosstalk budgeting
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      UCLA Previously Published Works (2014)
      Majority of practical multivariate statistical analysis and optimizations model interdependence among random variables in terms of the linear correlation. Though linear correlation is simple to use and evaluate, in several cases non-linear dependence between random variables may be too strong to ignore. In this paper, we propose polynomial correlation coefficients as simple measure of multi-variable non-linear dependence and show that the need for modeling non-linear dependence strongly depends on the end function that is to be evaluated from the random variables. Then, we calculate the errors in estimation resulting from assuming independence of components generated by linear de-correlation techniques, such as PCA and ICA. The experimental results show that the error predicted by our method is within 1% error compared to the real simulation of statistical timing and leakage analysis. In order to deal with non-linear dependence, we further develop a target-function-driven component analysis algorithm (FCA) to minimize the error caused by ignoring high order dependence. We apply FCA to statistical leakage power analysis and SRAM cell noise margin variation analysis. Experimental results show that the proposed FCA method is more accurate compared to the traditional PCA or ICA. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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        LBL Publications (2002)
          Cover page: Comparison of AlxGa1-xN films grown on sapphire by MBE under N-rich and Ga-rich conditions
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          UC Berkeley Previously Published Works (2016)
          Ultrafast optical heating of the electrons in ferrimagnetic metals can result in all-optical switching (AOS) of the magnetization. Here we report quantitative measurements of the temperature rise of GdFeCo thin films during helicity-independent AOS. Critical switching fluences are obtained as a function of the initial temperature of the sample and for laser pulse durations from 55 fs to 15 ps. We conclude that nonequilibrium phenomena are necessary for helicity-independent AOS, although the peak electron temperature does not play a critical role. Pump-probe time-resolved experiments show that the switching time increases as the pulse duration increases, with 10 ps pulses resulting in switching times of ∼13 ps. These results raise new questions about the fundamental mechanism of helicity-independent AOS.
            Cover page: Role of electron and phonon temperatures in the helicity-independent all-optical switching of GdFeCo
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            UCLA Previously Published Works (2009)
            Two recent genome-wide association studies have identified several novel type 2 diabetes susceptibility variants in intron 15 of the KCNQ1 gene. We aimed to evaluate the effects of the variants in KCNQ1 on type 2 diabetes and metabolic traits in the population of mainland China. Three candidate single nucleotide polymorphisms were genotyped in 1,912 individuals with type 2 diabetes and 2,041 normal controls using the ligase detection reaction method. We confirmed the association of KCNQ1 with type 2 diabetes in the population of mainland China. Allele frequency ORs of the three single nucleotide polymorphisms (SNPs) were: rs2237892 (OR 1.19, 95% CI 1.08–1.31, p = 3.0 × 10−4); rs2237895 (OR 1.20, 95% CI 1.09–1.32, p = 1.9 × 10−4); and rs2237897 (OR 1.24, 95% CI 1.13–1.36, p = 3.9 × 10−5). We also found a significant difference in the distribution of the global haplotypes between the type 2 diabetes group and the normal control group (p = 2.6 × 10−5). In addition, in the control group SNP rs2237892 was marginally associated with increasing fasting plasma glucose and SNPs rs2237892 and rs2237897 were associated with HbA1c. Furthermore, for all three variants, homozygous carriers of the diabetes-associated allele had significantly decreased BMI and waist circumferences. Our investigation confirmed the effects of KCNQ1 variants on type 2 diabetes risk in the Chinese population.
              Cover page: Variants in KCNQ1 are associated with susceptibility to type 2 diabetes in the population of mainland China
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              UC Berkeley Previously Published Works (2016)
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                UCLA Previously Published Works (2016)
                We present high precision measurements of elliptic flow near midrapidity (|y|<1.0) for multistrange hadrons and ϕ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy √[sNN]=200  GeV. We observe that the transverse momentum dependence of ϕ and Ω v2 is similar to that of π and p, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0%-30% and 30%-80% collision centrality. There is an indication of the breakdown of previously observed mass ordering between ϕ and proton v2 at low transverse momentum in the 0%-30% centrality range, possibly indicating late hadronic interactions affecting the proton v2.
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                  UCLA Previously Published Works (2015)
                  We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in p^{↑}+p collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of 5 standard deviations at high transverse momenta, at high pseudorapidities η>0.5, and for pair masses around the mass of the ρ meson. This is the first direct transversity measurement in p+p collisions.
                    Creative Commons 'BY-NC-ND' version 4.0 license
                    • Article
                    • Peer Reviewed
                    UCLA Previously Published Works (2015)
                    Dihadron correlations are analyzed in √sNN = 200 GeV d + Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions.
                      Cover page: Effect of event selection on jetlike correlation measurement in d+Au collisions at sNN=200&nbsp;GeVCreative Commons 'BY-NC-ND' version 4.0 license
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