A biomorphic digital image sensor

An arbitrated address-event imager has been designed and fabricated in a 0.6-/spl mu/m CMOS process. The imager is composed of 80 /spl times/ 60 pixels of 32 /spl times/ 30 /spl mu/m. The value of the light intensity collected by each photosensitive element is inversely proportional to the pixel's interspike time interval. The readout of each spike is initiated by the individual pixel; therefore, the available output bandwidth is allocated according to pixel output demand. This encoding of light intensities favors brighter pixels, equalizes the number of integrated photons across light intensity, and minimizes power consumption. Tests conducted on the imager showed a large output dynamic range of 180 dB (under bright local illumination) for an individual pixel. The array, on the other hand, produced a dynamic range of 120 dB (under uniform bright illumination and when no lower bound was placed on the update rate per pixel). The dynamic range is 48.9 dB value at 30-pixel updates/s. Power consumption is 3.4 mW in uniform indoor light and a mean event rate of 200 kHz, which updates each pixel 41.6 times per second. The imager is capable of updating each pixel 8.3K times per second (under bright local illumination).     

Bias-temperature instabilities of polysilicon gate HfO/sub 2/ MOSFETs

Bias-temperature instabilities (BTI) of HfO/sub 2/ metal oxide semiconductor field effect transistors (MOSFETs) have been systematically studied for the first time. NMOS positive BTI (PBTI) exhibited a more significant V/sub t/ instability than that of PMOS negative BTI (NBTI), and limited the lifetime of HfO/sub 2/ MOSFETs. Although high-temperature forming gas annealing (HT-FGA) improved the interface quality by passivating the interfacial states with hydrogen, BTI behaviors were not strongly affected by the technique. Charge pumping measurements were extensively used to investigate the nature of the BTI degradation, and it was found that V/sub t/ degradation of NMOS PBTI was primarily caused by charge trapping in bulk HfO/sub 2/ rather than interfacial degradation. Deuterium (D/sub 2/) annealing was found to be an excellent technique to improve BTI immunity as well as to enhance the mobility of HfO/sub 2/ MOSFETs.     

NUMERICAL ANALYSIS OF THE EFFECTS OF LOCAL HYDRODYNAMICS ON MASS TRANSFER IN HETEROGENEOUS POROUS MEDIA

Many engineering problems require the estimation of mass transfer coefficients in porous materials. In heterogeneous materials or in cases where mass transfer sites are not spatially uniform, empirical equations for mass transfer coefficients vary widely, and the origin of these differences is not well understood. In this article, we use a stochastic algorithm to model mass transfer from single particles in a two-dimensional heterogeneous packed bed. The computed mass transfer coefficients are used to generate a distribution of local Peclet numbers in the bed. Detailed hydrodynamics are then used to interpret variations in the local Peclet number. The results show clear relationships between pore structure, streamline patterns, and mass transfer rates.     

Orthogonal space-time block codes: maximum likelihood detection for unknown channels and unstructured interferences

Space-time coding (STC) schemes for communication systems employing multiple transmit and receive antennas have been attracting increased attention. The so-called orthogonal space-time block codes (OSTBCs) have been of particular interest due to their good performance and low decoding complexity. In this paper, we take a systematic maximum-likelihood (ML) approach to the decoding of OSTBC for unknown propagation channels and unknown noise and interference conditions. We derive a low-complexity ML decoding algorithm based on cyclic minimization and assisted by a minimum amount of training data. Furthermore, we discuss the design of optimal training sequences and optimal information transfer to an outer decoder. Numerical examples demonstrate the performance of our algorithm.     

QMTool: an XML-based management platform for QoS-aware IP networks

Technological and human factors have contributed to the increasing complexity of the network management problem. Heterogeneity and globalization of network resources have, on one hand, increased user expectations for flexible and easy-to-use environments and, on the other, propounded entirely novel ways to face the management problem. Several research efforts recognize the need for integrated solutions to manage both network resources and services in open and global environments. Undoubtedly, these solutions should permit the coexistence of different management models and should interoperate with legacy systems. The presented management system, QoS management tool (QMTool), aspires to address the heterogeneity, complexity, and dynamic behavior of QoS-enabled IP networks by taking advantage of the optimum fit of a number of novel technologies. A layered framework architecture, including element, network management, and visualization service, is provided, and a high level of information abstraction in network configuration and monitoring is introduced mainly based on the capabilities of the Extensible Markup Language (XML). Moreover, the functional components for providing (re-)configuration, fault management monitoring, and network visualization facilities are also presented, followed by notes of implementation issues.     

Threshold sensitivity of anti-Stokes frequency converter

Expressions describing the threshold sensitivity of a quantum converter of IR radiation into visible light are obtained for two schemes of energy levels in the active atoms. Based on these expressions, practical criteria for the creation of such devices are formulated.     

The stress-whitened damage zone of PVC blends

The stress-whitened damage zone that formed ahead of a semicircular notch during slow tensile loading has been measured from optical micrographs of translucent blends of poly(vinyl chloride) (PVC) with experimental chlorinated polyethylene (CPE) resins. When the zone was small, the plane strain condition applied and from the elastic stress distribution a constant mean stress condition was found at the boundary of the crescent-shaped zone. The critical mean stress did not depend on the chlorine content or the chlorine distribution of the experimental CPE resin used in the blend. While the critical mean stress decreased as the amount of CPE in the blend was increased, the critical volume strain, calculated from the bulk modulus, was independent of composition and was thought to be the controlling parameter for stress-whitening. When the zone was larger, the shape was qualitatively described by concepts of stress redistribution in the presence of a plastic zone ahead of the notch. Macroscopic flow and necking were only detected near the maximum in the stress-displacement curve.     

Catalysis of linoleate oxidation by soluble chicken muscle proteins

A soluble fraction of a chickenMusculus gastrocnemius muscle was used to characterize the catalyst of linoleate oxidation. Separation of the chicken muscle extract into low (free metal) and high (protein) molecular weight fractions revealed that the molecular weight of the major catalyst of linoleate oxidation in chicken muscle extract was greater than 700 daltons. Catalysis of linoleate oxidation by the protein fraction exhibited a pH optimum of 5.9. Subjecting the protein fraction to heat treatments at increasing temperatures (30–90 C) decreased the catalysis of linoleate oxidation. Addition of two mM EDTA had no effect on the catalysis of linoleate oxidation. Cyanide (2 mM), glutathione (1 mM) and cysteine (1 mM) decreased the oxidation of linoleate by the protein fraction 21.0%, 22.9% and 29.0% respectively. Characterization of the oxidative catalyst in chicken muscle extract indicated that free metals and hemoproteins contribute to overall catalysis of linoleate oxidation but are not the sole catalysts. Heat inactivation of the oxidative catalyst and the observed pH optimum suggests that the unidentified catalyst is proteinacious and may be an enzyme.