Multichannel neural recording system based on family ASICs processed in submicron technology

In this paper we present a measurement system for in vivo multichannel recordings of the electrophysiological activity of brain tissue. The system consists of penetrating Microelectrode Array (MEA), three versions of a Conditioning Module each equipped with different Application Specific Integrated Circuits (ASIC), Digitizer and PC Application for recorded data presentation and storage. The MEA consists of 64 15 μm diameter microelectrodes. The multichannel ASICs amplify and filter field and action potential signals. The custom-made Digitizer Module simultaneously acquires data from all channels with a 14 kS/s sample rate and 12 bit resolution. The resulting byte stream (about 2 MB/s) is transmitted to the PC via USB (Universal Serial Bus). Eventually the measurement data is decoded, presented to the system user and stored on a HDD. Preliminary system tests confirm its excellent performance (low input refereed noise, low power consumption, low area occupancy, ability of Action Potentials/Local Field Potentials separation). Our system equipped with multichannel ASICs meets requirements of many different neurobiology experiments.     

Accurate computation of Zernike moments in polar coordinates.

An algorithm for high-precision numerical computation of Zernike moments is presented. The algorithm, based on the introduced polar pixel tiling scheme, does not exhibit the geometric error and numerical integration error which are inherent in conventional methods based on Cartesian coordinates. This yields a dramatic improvement of the Zernike moments accuracy in terms of their reconstruction and invariance properties. The introduced image tiling requires an interpolation algorithm which turns out to be of the second order importance compared to the discretization error. Various comparisons are made between the accuracy of the proposed method and that of commonly used techniques. The results reveal the great advantage of our approach.     

Fault impact and fault tolerance in multiprocessor interconnection networks

Growing complexity of parallel machines coupled with increasing chip densities escalates the need for fault tolerance and recovery in these systems. In pursuit of the goal of fault-tolerant multiprocessors, many techniques have been proposed. Since methods for designing fault-tolerant processors and memories are relatively mature, the techniques considered in this paper focus on the interconnection network (ICN) linking the processors. The impact of faults on non-fault-tolerant ICNs is contrasted with that in fault-tolerant networks. Fault tolerance in ICNs is addressed at two levels, inter-node or switch level and system level. Inter-node or switch level pertains to data and control integrity and system level deals with maintaining network connectivity and adequate performance levels in the presence of faults. Fault-tolerant schemes at the switching element level warrant some form of concurrent error detection such as the use of codes usually combined with a full handshake protocol. Space–time trade-offs involved in the use of various codes and protocols are investigated. At the system level, several augmented multi-stage switching ICNs, tree and ring networks are studied. The combined provision for fault tolerance together with improved performance in the non-fault condition is emphasized. Finally, strategies for network reconfiguration and rerouting after system failure are presented.     

Atomic migration on ordering and diffusion in bulk and nanostructured FePt intermetallic

“Order-order” kinetics was studied by means of in situ and quasi-residual resistometry in bulk polycrystal stoichiometric L1₀-ordered FePt and in epitaxially deposited FePt thin film. In addition, Fe diffusion in FePt thin film was examined by means of a combination of nuclear resonant scattering and nuclear tracer techniques. In bulk FePt, a discontinuous drop of the activation energy for chemical ordering (from 2.7–15 eV) was detected below 850 K, definitely away from the Curie point (735 K). The activation energy for Fe radiotracer diffusion in the FePt thin film studied below 900 K was found to be equal to 1.7 eV (in view of the value higher than 3 eV measured above 1100 K). Kinetic Monte Carlo simulations of order-order processes in bulk and nanolayered FePt reproduced their experimentally observed multi-time-scale character. In simulated FePt nanolayers, a reorientation of the initial z-variant L1₀ superstructure into a mixture of x and y variants was definitely a dominating process.     

汽油和柴油混合燃料均质压燃(HCCI)的试验研究

汽油和柴油这两种不同特性的燃料被用作HCCI发动机的燃料。汽油具有高挥发性、易雾化和易于形成混合气的特性,被用来形成均质混合气;柴油具有良好的着火性和可燃性,被用来控制自燃和限制爆震燃烧。期望这两种特性不同而又相互补充的燃料混合后能够达到一个折衷的HCCI的燃烧性能。试验在一个专用于HCCI研究的单缸发动机上实施,采用两种中等的压缩比(10．4和15)和两种HCCI模式(进气加热和负气门叠开),试验结果证实了这种期望。结果是:随着混合燃料中柴油比例的增加,对于进气加热模式,HC- CI能稳定工作所需要的进气温度有所降低,对于负气门叠开模式,缸内平均指示压力和过量空气系数的范围有所扩展,并且两种方式下HC和NOx的排放均有所减少。     

Simple method of selecting totalistic rules for pseudorandom number generator based on nonuniform cellular automaton

The Journal of Supercomputing - This paper is devoted to selecting rules for one-dimensional (1D) totalistic cellular automaton (TCA). These rules are used for the generation of pseudorandom...