Long resonator micromachined tunable GaAs-AlAs Fabry-Perot filter

We present novel concepts for tunable optical filters. Long resonant cavities of about 30-/spl mu/m length have been realized with two-chip designs. GaAs technology has been applied to filters that are designed for the use in dense wavelength-division multiplexing (WDM) at wavelengths around 1550 nm. A finesse of 46.7, a full-width at half-maximum (FWHM) of 1.2 nm and electrostatic tuning over a range of 103 nm with an applied voltage of 35 V has been achieved. An alternative tuning concept that allows to tune the resonator length 4 /spl mu/m by heating Ni-Cr resistors placed on the suspending beams of a membrane with an applied voltage of 2.7 V has been realized.     

A Noise-Insensitive Compromise Gradient Method for the Adjustment of Adaptive Echo Cancellers

The time-optimum gradient method for the coefficient adjustment of adaptive echo cancellers allows a fast adjustment and a high echo return loss enhancement (ERLE) in the noise-free case. If noise occurs on the echo path, a compromise is necessary between the relatively large step size needed for rapid convergence and the relatively small step size needed for noise insensitivity. In this paper a noise-insensitive compromise method is proposed, which guarantees an acceptable ERLE in the noise-free case, as well as under line noise conditions. The method has, furthermore, the advantage of being easily instrumented. The efficiency of the proposed algorithm is determined by computer simulations under realistic conditions with two algorithms frequently used in previous publications: with the time-optimum gradient method and with a method with constant step-size factor. The simulations were carried out with floating-point arithmetic and with fixed-point arithmetic with 16 and 12 bit resolution to determine the maximum performance and necessary implementation expense of the different adjustment methods.     

Artificial intelligence: consciousness and conscience

AI & SOCIETY - Our society is in the middle of the AI revolution. We discuss several applications of AI, in particular medical causality, where deep-learning neural networks screen through big...     

Examining the cross-race effect in lineup identification using Caucasian and First Nations samples.

This study examined whether findings from research on the cross-race effect (CRE) in eyewitness memory with Caucasian-Black samples can be generalised to Caucasian-First Nations pairings in a lineup identification task. This study used a novel approach to investigate the CRE, using six targets, as well as simultaneous lineups that included both target-present and target-absent arrays. This study also addressed the efficacy of the contact hypothesis as it applies to these populations. A significant CRE was discovered. Furthermore, both Caucasian and First Nations participants were more likely to choose from the lineup when attempting to recognise First Nations faces than when attempting to recognise Caucasian faces. Contact with the other race had no effect on recognition accuracy of that race. Potential implications and directions for future research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formant and Pitch Detection Using Time-Frequency Distribution

The Wigner-Ville distribution of a multi-component signalhas a unique structure. Based on this structure, a formant and pitchestimation method for speech signals is introduced. Formants andpitch estimated with this method are more accurate, have betterresolution, and are easier to recognize than those estimated by othermethods. A one pitch-period segment is adequate for formantestimation while a minimal two pitch-period segment is needed forboth pitch and formant detection with one step. Experimental resultsare provided to demonstrate the performance of this method, andcomparisons with other methods are provided.     

Experimental testing of the polymer–filler gel formation theory. II.

In Part I of the present article predictions of the polymer–filler gel formation theory were tested experimentally using fine-particle silica in natural rubber (NR) and in styrene–butadiene rubber (SBR). Part II brings a more detailed experiment–theory comparison using carbon blacks differing in specific surface area and structure, graphitized blacks, fume silica, and surface-modified (hydrophobized) fume silica. In the region of low and medium filler concentration c, the c-dependence of the fraction G of polymer in polymer–filler gel, of the fraction B of total filler-bound polymer, of the fraction w_disp of solvent-dispersed filler particles were found to be correctly predicted by the theory. The effect of filler characteristics and of the method of its incorporation into the polymer on the values of the adjustable parameters of the theory (filler surface adsorptivity, D, and filler particles connectivity, f) was determined and is discussed. In the region of very high c increasing positive deviations of D from the low-c behavior were observed and an explanation for this effect is proposed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 95–107, 1998     

3D optical coherence tomography as new tool for microscopic investigations of nucleate boiling on heated surfaces

Boiling phenomena are an important aspect in security and efficiency for technical applications with high heat flux like nuclear reactors. This study presents optical coherence tomography (OCT) as a novel modality for three-dimensional and two-dimensional time resolved imaging of nucleate boiling on heated surfaces on a microscopic scale with high spatial (<10 μm) and temporal (>25 frames per second) resolution. Within this study, a borosilicate glass plate coated with an optically transparent and electrically conductive indium tin oxide (ITO) layer with a thickness of approximately 100 nm was used as heating surface. The combination of these two properties allows optical inspection of the nucleate boiling from the backside by OCT focused on the formation, growth and detachment of single bubbles. We demonstrated for the first time that OCT is an excellent tool to acquire two-dimensional and three-dimensional images of the base of vapor bubbles from the backside of the heated surface. The acquired images allow for instance the temporally resolved measurement of the bubble diameter, diameter of the bubble base and the contact angle. Exploiting the phase information of the acquired OCT signal stacks allows imaging the movement of the bubble surrounding fluid. We think that OCT will provide many new insights into the boiling phenomena at the bubble base. The recent enhancement of the acquisition rates of OCT systems will facilitate four-dimensional imaging of single bubble evaporation procedures in the nearer future.     

Self-assembly as a route to one-dimensional lanthanum(Ⅲ) salicylaldimine coordination polymer

The self-assembled formation of a one-dimensional lanthanum salicylald imine coordination polymer was proved by the X-ray diffraction analysis of new l anthanum(Ⅲ) nitrate complex containing N,N’-bis(salicylidene)-1,5-pentanediami ne ligand(H2L) . It was obtained in situ in a one-step,metal-templated condensa tion of salicylaldehyde with 1,5-pentanediamine(cadaverine,biogenic polyamine) and characterized by microanalysis and spectroscopic(IR,ESI-MS,UV-Vis,and 1 H NMR) data. The [La(NO3) 3(μ-H2L) 2]∞ complex displayed 10-coordinate distorted bicapped dodecahedron geometry with unusual coordination pattern of undeprotonat ed salicylaldimines which acted as μ-bridging ditopic ligands using exclusivel y the oxygens as donor atoms with the nitrogen atoms not being involved in the c oordination environment.