Karlsruhe Institute of Technology

About: Karlsruhe Institute of Technology is a education organization based out in Karlsruhe, Germany. It is known for research contribution in the topics: Computer science & Catalysis. The organization has 37946 authors who have published 82138 publications receiving 2197068 citations. The organization is also known as: KIT & University of Karlsruhe.

A low latency generic accuracy configurable adder

Abstract: High performance approximate adders typically comprise of multiple smaller sub-adders, carry prediction units and error correction units In this paper, we present a low-latency generic accuracy configurable adder to support variable approximation modes It provides a higher number of potential configurations compared to state-of-the-art, thus enabling a high degree of design flexibility and trade-off between performance and output quality An error correction unit is integrated to provide accurate results for cases where high accuracy is required Furthermore, an associated scheme for error probability estimation allows convenient comparison of different approximate adder configurations without requiring the need to numerically simulate the adder Our experimental results validate the developed error model and also the lower latency of our generic accuracy configurable adder over state-of-the-art approximate adders For functional verification and prototyping, we have used a Xilinx Virtex-6 FPGA Our adder model and synthesizable RTL are made open-source

Combined Deconvolution and CNLS Fitting Approach Applied on the Impedance Response of Technical Ni ∕ 8YSZ Cermet Electrodes

Abstract: A high-resolution impedance study of the hydrogen oxidation in Ni/8YSZ (yttria-stabilized zirconia) cermet anodes has been realized in consideration of a broad range of operating conditions (temperature and partial pressure of fuel gas components H 2 , H 2 O, N 2 , He). A major problem in this respect concerns the origin and physical interpretation of empirical equivalent circuits used to fit the experimental data. We applied a two-stage approach for the evaluation of the impedance data: (i) at first, by the deconvolution of a distribution function of relaxation times (DRT), four different processes and their characteristic relaxation times have been identified. Two processes at frequencies < 1 kHz represent a gas-conversion process or, respectively, a gas diffusion, whereas two processes at higher frequencies (2-30 kHz) are associated with the electro-oxidation of hydrogen at active sites, including the charge transfer reaction and the ionic transport. (ii) Subsequently, the last mentioned processes were fitted to a "transmission line" model describing the electronic and ionic transport properties of the Ni/8YSZ cermet. The high resolution of the DRT combined with the numeric accuracy of the complex nonlinear least square (CNLS) fit enabled us to determine (i) the effective ionic conductivity of the Ni/8YSZ cermet, (ii) the spatial extension of the electrochemically active area adjacent to the electrolyte/electrode interface, and (iii) the charge transfer resistance and its thermal activation energy.

Tropospheric Ozone Assessment Report: Present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation

Abstract: The Tropospheric Ozone Assessment Report (TOAR) is an activity of the International Global Atmospheric Chemistry Project. This paper is a component of the report, focusing on the present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation. Utilizing the TOAR surface ozone database, several figures present the global distribution and trends of daytime average ozone at 2702 non-urban monitoring sites, highlighting the regions and seasons of the world with the greatest ozone levels. Similarly, ozonesonde and commercial aircraft observations reveal ozone’s distribution throughout the depth of the free troposphere. Long-term surface observations are limited in their global spatial coverage, but data from remote locations indicate that ozone in the 21st century is greater than during the 1970s and 1980s. While some remote sites and many sites in the heavily polluted regions of East Asia show ozone increases since 2000, many others show decreases and there is no clear global pattern for surface ozone changes since 2000. Two new satellite products provide detailed views of ozone in the lower troposphere across East Asia and Europe, revealing the full spatial extent of the spring and summer ozone enhancements across eastern China that cannot be assessed from limited surface observations. Sufficient data are now available (ozonesondes, satellite, aircraft) across the tropics from South America eastwards to the western Pacific Ocean, to indicate a likely tropospheric column ozone increase since the 1990s. The 2014–2016 mean tropospheric ozone burden (TOB) between 60˚N–60˚S from five satellite products is 300 Tg ± 4%. While this agreement is excellent, the products differ in their quantification of TOB trends and further work is required to reconcile the differences. Satellites can now estimate ozone’s global long-wave radiative effect, but evaluation is difficult due to limited in situ observations where the radiative effect is greatest.

Short Tree, Long Tree, Right Tree, Wrong Tree: New Acquisition Bias Corrections for Inferring SNP Phylogenies

Abstract: Single nucleotide polymorphisms (SNPs) are useful markers for phylogenetic studies owing in part to their ubiquity throughout the genome and ease of collection. Restriction site associated DNA sequencing (RADseq) methods are becoming increasingly popular for SNP data collection, but an assessment of the best practises for using these data in phylogenetics is lacking. We use computer simulations, and new double digest RADseq (ddRADseq) data for the lizard family Phrynosomatidae, to investigate the accuracy of RAD loci for phylogenetic inference. We compare the two primary ways RAD loci are used during phylogenetic analysis, including the analysis of full sequences (i.e., SNPs together with invariant sites), or the analysis of SNPs on their own after excluding invariant sites. We find that using full sequences rather than just SNPs is preferable from the perspectives of branch length and topological accuracy, but not of computational time. We introduce two new acquisition bias corrections for dealing with alignments composed exclusively of SNPs, a conditional likelihood method and a reconstituted DNA approach. The conditional likelihood method conditions on the presence of variable characters only (the number of invariant sites that are unsampled but known to exist is not considered), while the reconstituted DNA approach requires the user to specify the exact number of unsampled invariant sites prior to the analysis. Under simulation, branch length biases increase with the amount of missing data for both acquisition bias correction methods, but branch length accuracy is much improved in the reconstituted DNA approach compared to the conditional likelihood approach. Phylogenetic analyses of the empirical data using concatenation or a coalescent-based species tree approach provide strong support for many of the accepted relationships among phrynosomatid lizards, suggesting that RAD loci contain useful phylogenetic signal across a range of divergence times despite the presence of missing data. Phylogenetic analysis of RAD loci requires careful attention to model assumptions, especially if downstream analyses depend on branch lengths.