Clockless Stochastic Decoding of Low-Density Parity-Check Codes: Architecture and Simulation Model

This paper introduces clockless stochastic decoding for high-throughput low-density parity-check (LDPC) decoders. Stochastic computation provides ultra-low-complexity hardware using simple logic gates. Clockless decoding eliminates global clocking, which eases the worst-case timing restrictions of synchronous stochastic decoders. The lack of synchronization might use outdated bits to update outputs in computation nodes; however, it does not significantly affect output probabilities. A timing model of clockless-computation behaviours under a 90 nm CMOS technology is used to simulate the BER performance of the proposed decoding scheme. Based on our models, the proposed decoding scheme significantly reduces error floors due to the “lock-up” problem and achieves superior BER performance compared with conventional synchronous stochastic decoders. The timing model includes metastability to verify the affect on BER performance.     

Guest Editorial: Design and Implementation of DSP Systems

Convolution has been extensively used in image processing and computer vision, including image enhancement, smoothing, and structure extraction. However, convolution operation typically requires a significant amount of computing resources. A novel one-dimensional (1D) convolution processor with reconfigurable architecture is implemented in this study. This processor is a combination of a line buffer, controller units, as well as a reconfigurable and separable convolution module. The use of a reconfigurable architecture and separable convolution approach improves the flexibility and performance of the convolution processor. The reconfigurable and separable convolution array, which is the main component of the processor, can simultaneously execute convolution operation with different kernels, with a maximum kernel size of up to 24 × 24. Experimental results show that the maximum frames rate of the processor is approximately 194 frames per second (fps), which exceeds the real-time requirement. Synthesis results show that the processor occupies 13.39 mm ² at a 204 MHz system clock and consumes a power of 419 mW at maximum kernel size at a 120 MHz system clock in SMIC 0.18 μm CMOS technology. Verification experiments on field programmable gate arrays (FPGAs) demonstrate that the processor is suitable for real-time image processing applications even for high-resolution images.     

Dynamic resource allocation in OFDM systems: an overview of cross-layer optimization principles and techniques

Recently, a lot of research effort has been spent on cross-layer system design. It has been shown that cross-layer mechanisms (i.e., policies) potentially provide significant performance gains for various systems. In this article we review several aspects of cross-layer system optimization regarding wireless OFDM systems. We discuss basic optimization models and present selected heuristic approaches realizing cross-layer policies by means of dynamic resource allocation. Two specific areas are treated separately: models and dynamic approaches for single transmitter/receiver pairs (i.e., a point-to-point communication scenario) as well as models and approaches for point-to-multipoint communication scenarios (e.g., the downlink of a wireless cell). This article provides basic knowledge in order to investigate future OFDM cross-layer-optimization issues     

EXAFS as Powerful Analytical Tool for the Investigation of Organic–Inorganic Hybrid Materials

The potential and application of X‐ray absorption spectroscopy (XAS) for structural investigations of organic–inorganic hybrid materials, with a special emphasis on systems consisting of inorganic building blocks (clusters) embedded into polymer backbones, is extensively reviewed. In the first part of the paper, the main features of organic–inorganic hybrid materials, their classification, the synthetic approaches for their preparation, and their applications are concisely presented, whereas the particular issues related to their characterization are discussed in more detail. In the second section of the paper, the principles and the theoretical background of the XAS method, including experimental design, data reduction, evaluation, analysis, and interpretation are described and discussed. Examples of potentialities of the method for the short‐range structural investigation of inorganic nanostructures in hybrids are provided, and the state‐of‐the‐art in the field of hybrid materials is reviewed. In the third part, six different case studies belonging to our past and present experience in this field are presented and discussed, with a particular focus on their XAS investigation.     

Detection of nanoscale etch and ash damage to nanoporous methyl silsesquioxane using electrostatic force microscopy

We have used electrostatic force microscopy (EFM) to detect nanoscale dielectric constant variations resulting from damascene processing of blanket and patterned films of nanoporous methyl silsesquioxane (MSQ) (k = 2.2). Ash processing can cause significant degradation of the dielectric constant for both blanket and patterned MSQ films if the film is exposed to moisture. We have observed that this degradation is reversible because the apparent dielectric constant of the ashed film is nearly the same as the as-deposited film if the film is baked at 80-150 °C. Reactive ion etching (RIE) causes ∼100 nm deep side wall damage in patterned samples as well as leaving a redeposited layer that has a higher dielectric constant. We also present some initial results that show the strength of the EFM signal is humidity dependent.     

The social costs of emotional suppression: A prospective study of the transition to college.

There is growing interest in understanding how emotion regulation affects adaptation. The present study examined expressive suppression (which involves inhibiting the overt expression of emotion) and how it affects a critical domain of adaptation, social functioning. This investigation focused on the transition to college, a time that presents a variety of emotional and social challenges. Analyses focused on 2 components of suppression: a stable component, representing individual differences expressed both before and after the transition, and a dynamic component, representing variance specific to the new college context. Both components of suppression predicted lower social support, less closeness to others, and lower social satisfaction. These findings were robustly corroborated across weekly experience reports, self-reports, and peer reports and are consistent with a theoretical framework that defines emotion regulation as a dynamic process shaped by both stable person factors and environmental demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit Contact Handling for Deformable Objects

We present an algorithm for robust and efficient contact handling of deformable objects. By being aware of the internal dynamics of the colliding objects, our algorithm provides smooth rolling and sliding, stable stacking, robust impact handling, and seamless coupling of heterogeneous objects, all in a unified manner. We achieve dynamicsawareness through a constrained dynamics formulation with implicit complementarity constraints, and we present two major contributions that enable an efficient solution of the constrained dynamics problem: a time stepping algorithm that robustly ensures non-penetration and progressively refines the formulation of constrained dynamics, and a new solver for large mixed linear complementarity problems, based on iterative constraint anticipation. We show the application of our algorithm in challenging scenarios such as multi-layered cloth moving at high velocities, or colliding deformable solids simulated with large time steps.     

α-Substituierte Phosphonate. 40. 1-Trimethylammonium-1-diethylphosphono-1-cyanomethylid,ein stabiles N-Ylid

α-Substituted Phosphonates. 40. 1-Trimethylammonium-1-diethylphosphono-1-cyanomethylid, a Stable N-Ylid Diethyl-1-dimethylamino-1-cyanomethanephosphonate 4 can be alkylated on nitrogen to the quarternary ammoniumsalts 5 , which by C-deprotonation gives the stable N-ylid 8 . The N-ylid 8 behaves inert against carbonyl compounds and acylating agents, but can be C-alkylated and — involving an ester-dealkylation — C-chlorinated.     

α-Substituierte Phosphonate. 39. Methandiphosphonsäureester durch UV-induzierte Michaelis-Becker-Reaktion

α-Substituted Phosphonates. 39. Methane-diphosphonic Esters by U.V.-Induced Michaelis-Becker-Reaction Dibromomethane resp. chlorbromomethane reacts with sodium dialkyl phosphite in heptane-/liq.NH₃ or in liq. NH₃ by u.v. irradiation at low temperatures to give in good yields methane diphosphonic acid tetraalkylesters 1 . In the same manner with sodium diethyl thionophosphite the corresponding methane-bis-thiophosphonic acid tetraethylester 4 is obtained.