Mismatch Modeling and Simulation—A Comprehensive Approach

This article describes a comprehensive approach to mismatch simulation and modeling as needed for integrated circuit design. Local device mismatch as well as global process variations and parameter correlations are regarded. A method for mismatch modeling based on spatial frequencies is described, which enables to overcome insufficiencies of the first order models. Measurement results are presented to demonstrate the achieved modeling precision. All models and methods mentioned here are commercially available in the simulation tool GAME (General Analysis of Mismatch Effects) which is used in the semiconductor industry since 1998.     

Reconciling fault-tolerant distributed computing and systems-on-chip

Classic distributed computing abstractions do not match well the reality of digital logic gates, which are the elementary building blocks of Systems-on-Chip (SoCs) and other Very Large Scale Integrated (VLSI) circuits: Massively concurrent, continuous computations undermine the concept of sequential processes executing sequences of atomic zero-time computing steps, and very limited computational resources at gate-level make even simple operations prohibitively costly. In this paper, we introduce a modeling and analysis framework based on continuous computations and zero-bit message channels, and employ this framework for the correctness & performance analysis of a distributed fault-tolerant clocking approach for Systems-on-Chip (SoCs). Starting out from a “classic” distributed Byzantine fault-tolerant tick generation algorithm, we show how to adapt it for direct implementation in clockless digital logic, and rigorously prove its correctness and derive analytic expressions for worst case performance metrics like synchronization precision and clock frequency. Rather than on absolute delay values, both the algorithm’s correctness and the achievable synchronization precision depend solely on the ratio of certain path delays. Since these ratios can be mapped directly to placement & routing constraints, there is typically no need for changing the algorithm when migrating to a faster implementation technology and/or when using a slightly different layout in an SoC.     

Thiophene‐ and silarylene‐containing polyesters. Resonance effect on conductivity after polarization in an external electric field

Polyesters were synthesized by direct polycondensation of thiophene‐2,5‐dicarboxylic acid and five different silarylene‐containing diphenols using a tosyl chloride/pyridine/N,N‐dimethylformamide system as a condensing agent. Polymers were obtained in good yields and were characterized using Fourier transform infrared and NMR (¹H, ¹³C, 135‐DEPT and ²⁹Si) spectroscopy and elemental analysis. All polymers were completely soluble in aprotic organic polar solvents such as dimethylformamide, dimethylsulfoxide and N‐methyl‐2‐pyrrolidone. The range of effective mass of the polymers (m/z) was 1 × 10⁵–2 × 10⁵, determined using electrospray ionization mass spectrometry. Asymmetry and steric hindrance prevented dense packing of the polymeric chains, showing glass transition temperatures between ? 78 and ? 51 °C and loss of thermal stability at 177–199 °C (10% weight loss). Additionally, the melting points of the polyesters were found to be in the range 62–67 °C. Because of this, the samples were semi‐solid at room temperature. The optical band gaps of the polymers were observed between 4.54 and 4.48 eV, corresponding in all cases to insulator behavior. The molecular structure of the samples was studied using X‐ray diffraction, showing a degree of order that was associated with two monoclinic lattices. Additionally, the conductivity was studied using a two‐point method with contacts on top of polymer films. Prior to the electrical measurement, the samples were polarized in an external electric field of 0.8 to 6.4 V cm^?1, and the alignment of the dipoles increased the electrical conductivity. Copyright © 2012 Society of Chemical Industry     

Evaluating experience sampling of stress in a single-subject research design

How can we measure subjective experiences or internal states? The rise of happiness as a variable of interest in policy decisions, for instance, necessitates appropriate methods for valid and practical measurements. This self-experimental work contributes to scientific development by analysing and evaluating three methods for recording stress: the experience sampling method with a smartphone, an adapted version of the day reconstruction method (DRM, a diary method) and an ubiquitous biophysical measure of the heart rate. All three methods yield significant treatment effects for eight “natural experiments” as stressors. Surprisingly, the DRM outperforms the other two methods in a simple factor analysis and appears to have no recall bias. Also reactivity has no substantial impact, and an applied researcher should minimise the complexity of the input (amount and type of questions, interface and integration) rather than reduce the number of prompts. Some evidence suggests a Likert-type scale should be preferred over a continuous one. This work also reflects upon the nature of single-subject research and the role of the experimenter.     

Dauerhaftigkeit und mechanische Stabilität von Terrassendielen bei erhöhter Temperatur – Ein Werkstoffvergleich: WPC,thermisch modifiziertes Holz und Massivholz

This article deals with the differences in the long-term durability and thermal stability under load of terrace deckings from various materials. The tested materials were deckings made of wood, thermally modified timber (TMT), and wood–polymer–composites (WPC). For the determination of the test temperatures for component testing according to EN 310, the surface temperatures of the decks during a normal hot summer day were measured. A cyclic test according to EN 321 was applied to all decking materials. Afterwards the component testing was repeated. All wooden samples reveal considerable cracks, some were twisted, and few were even broken. In particular regarding the optical appearance, wood decks show advantages against the TMT decks. Some WPC decks show very fine cracks on the face, which were additionally analyzed by means of X-ray computed tomography (CT). Except for the WPC deck with higher wood content, no WPC deck revealed significant changes after the cyclic test. The CT analysis was also suitable to find cracks inside the materials and illustrate them. Thus, the whole damage inside a sample could be characterized by calculating a kind of error pattern. No considerable cracks or failures could be observed on the WPC decks.     

Layered precursors for new zeolitic materials: Synthesis and characterization of B-RUB-39 and its condensation product B-RUB-41

Condensation of layered silicate precursors leads to new, all silica zeolite frameworks. In order to introduce catalytic functionality, boron has been substituted into the silicate layer of RUB-39 in a single step synthesis process. Condensation of the silicate layer to the zeolite framework of RUB-41, RRO framework structure type, preserved B as constituent of the material. Analysis of structural details obtained from Rietveld analysis of powder diffraction data, ¹¹B and ²⁹Si NMR experiments of the as synthesized precursor as well as of the zeolite condensation product, and crystal chemical reasoning indicates segregation of B on one specific T-site. This T-site is buried in the silicate anionic layer of the precursor shielding the additional negative charge introduced by the trivalent T-atom.