Al2O3─SiC Composites from Aluminosilicate Precursors

Al₂O₃ and SiC composite materials have been produced from mixtures of aluminosilicates (both natural minerals and synthetic) and carbon as precursor materials. These composites are produced by heating a mixture of kaolinite (or synthetic aluminosilicates) and carbon in stoichiometric proportion above 1550°C, so that only Al₂O₃ and SiC remain as the major phases. A similar process has also been used for synthesizing other composite powders having mixtures of Al₂O₃, SiC, TiC, and ZrO₂ in different proportions (all compounds together or selective mixtures of some of them), as desired. The microstructure of hot-pressed dense compacts, produced from these powders, revealed that the SiC phase is distributed very homogeneously, even occasionally within Al₂O₃ grains on a nanosize scale. The homogeneous distribution of SiC particles within the system produced high fracture toughness of the hot-pressed material (K_IC∼ 7.0 MPa · m^1/2) and having Vicker's hardness values greater than 2000 kgf/mm².     

Electrophoretic deposition of carbon nanotubes

Electrophoretic deposition (EPD) has been gaining increasing interest as an economical and versatile processing technique for the production of novel coatings or films of carbon nanotubes (CNTs) on conductive substrates. The purpose of the paper is to present an up-to-date comprehensive overview of current research progress in the field of EPD of CNTs. The paper specifically reviews the preparation and characterisation of stable CNT suspensions, and the mechanism of the EPD process; it includes discussion of pure CNT coatings and CNT/nanoparticle composite films. A complete discussion of the EPD parameters is presented, including electrode materials, deposition time, electrode separation, deposition voltage and resultant electric field. The paper highlights potential applications of the resulting CNT and CNT/composite structures, in areas such as field emission devices, fuel cells, and supercapacitors.     

Remote sensing technique for near-surface wind by optical images of rough water surface

The study of a new remote-sensing technique for the investigation of near-surface wind fields is an important oceanographic problem. This article is focused on a new method of recording wind fields by the analysis of optical images of sea surface and range–time–intensity images (RTI images) of the sea surface. An RTI image constructed from optical profiles of the sea surface is an optical analogue of a side-looking radar image of the sea surface but has a higher spatial resolution and some possibility for remote sensing of sea roughness. It is possible to form RTI images with a range from some tens of metres to tens of kilometres, depending on the spatial resolution needed. A set of original optical devices for recoding RTI images using linear arrays of CCD-photodiodes was created. An analytical model of sea surface radiance for visible light was developed taking into account the polarization of light and shadowing of surface waves for grazing view geometry. The principle of remote sensing of near-surface winds by its manifestations on a waved surface under grazing angles based on a comparison of measured and modelled surface radiance is discussed. Investigations of near-surface wind field features in internal reservoirs and various regions of the seas during the last few years have been conducted by optical systems. The structure of near-surface wind fields, eddies, wind fronts, and katabatic wind flows for ranges from hundreds of metres to some tens of kilometres was recorded and analysed. Derived data of optical monitoring of water surfaces may serve for future investigations of near-surface wind features.     

Optimizing BRDF orientations for the manipulation of anisotropic highlights

This paper introduces a system for the direct editing of highlights produced by anisotropic BRDFs, which we call anisotropic highlights. We first provide a comprehensive analysis of the link between the direction of anisotropy and the shape of highlight curves for arbitrary object surfaces. The gained insights provide the required ingredients to infer BRDF orientations from a prescribed highlight tangent field. This amounts to a non‐linear optimization problem, which is solved at interactive framerates during manipulation. Taking inspiration from sculpting software, we provide tools that give the impression of manipulating highlight curves while actually modifying their tangents. Our solver produces desired highlight shapes for a host of lighting environments and anisotropic BRDFs.     

The metabolism of 1-acyl-PAF in rabbit platelets and its possible interaction with PAF

The metabolism of 1-acyl-2-acetyl-sn-glycero-3-phosphocholine (1-acyl-PAF), a naturally occurring analogue of platelet activating factor (PAF), was investigated in rabbit platelets. Our studies showed that 1-acyl-[³H]PAF (1-palmitoyl-2-acetyl-sn-glycero-3-phospho[N-methyl-³H]-choline) was converted by platelets into phosphatidyl-[³H]choline ([³H]PC) in a time-dependent fashion. The formation of [³H]PC occurred at a rate similar to that observed when lyso-[³H]PC (palmitoyl-sn-glycero-3-phospho[N-methyl-³H]choline) was used as substrate. In addition, a time-dependent increase in the level of water-soluble radioactivity was observed during the incubation of platelets with either 1-acyl-[³H]PAF or lyso-[³H]PC. This increase was parallel to the formation of [³H]PC and was not observed in the presence of [¹⁴C]PAF (1-octadecyl-2-acetyl-sn-glycerol-3-phospho[N methyl-¹⁴C]choline). Analysis by thin-layer chromatography showed that the soluble radioactivity was mainly associated with glycerophosphocholine (GPC). On the other hand, the preincubation of platelets with phenylmethylsulfonyl fluoride, an inhibitor of the acetylhydrolase, reduced the hydrolysis of 1-acyl-[³H]PAF to [³H]GPC with a concomitant accumulation of radioactivity in 1-acyl-PAF. These findings suggest that 1-acyl-PAF is converted into PC through deacetylation-reacylation with lysoPC as an obligatory intermediate. The findings also indicate that the lysoPC resulting from 1-acyl-PAF is either reacylated to phosphatidylcholine (PC) or hydrolyzed to GPC by lysophospholipase. Finally, we showed that the stimulation of platelets with PAF led to a time- and concentration-dependent increase in the conversion of 1-acyl-[³H]PAF to [³H]PC. The stimulatory effect of PAF was not observed when platelets were lysed before incubation, suggesting that PAF enhances the metabolism of 1-acyl-PAF, probably by accelerating its translocation through the plasma membrane.     

Flow-based reputation with uncertainty: evidence-based subjective logic

The concept of reputation is widely used as a measure of trustworthiness based on ratings from members in a community. The adoption of reputation systems, however, relies on their ability to capture the actual trustworthiness of a target. Several reputation models for aggregating trust information have been proposed in the literature. The choice of model has an impact on the reliability of the aggregated trust information as well as on the procedure used to compute reputations. Two prominent models are flow-based reputation (e.g., EigenTrust, PageRank) and subjective logic-based reputation. Flow-based models provide an automated method to aggregate trust information, but they are not able to express the level of uncertainty in the information. In contrast, subjective logic extends probabilistic models with an explicit notion of uncertainty, but the calculation of reputation depends on the structure of the trust network and often requires information to be discarded. These are severe drawbacks. In this work, we observe that the ‘opinion discounting’ operation in subjective logic has a number of basic problems. We resolve these problems by providing a new discounting operator that describes the flow of evidence from one party to another. The adoption of our discounting rule results in a consistent subjective logic algebra that is entirely based on the handling of evidence. We show that the new algebra enables the construction of an automated reputation assessment procedure for arbitrary trust networks, where the calculation no longer depends on the structure of the network, and does not need to throw away any information. Thus, we obtain the best of both worlds: flow-based reputation and consistent handling of uncertainties.     

3D resistive RAM cell design for high-density storage class memory—a review

In this article, we comprehensively review recent progress in the ReRAM cell technology for 3D integration focusing on a material/device level. First we briefly mention pioneering work on high-density crossbar ReRAM arrays which paved the way to 3D integration. We discuss the two main proposed 3D integration schemes—3D horizontally stacked ReRAM vs 3D Vertical ReRAM and their respective advantages and disadvantages. We follow with the detailed memory cell design on important work in both areas, utilizing either filamentary or interface-limited switching mechanisms. We also discuss our own contributions on HfO₂-based filamentary 3D Vertical ReRAM as well as TaO_x/TiO₂ bilayer-based self-rectifying 3D Vertical ReRAM. Finally, we summarize the present status and provide an outlook for the nearterm future.     

Geiringer theorems: from population genetics to computational intelligence, memory evolutive systems and Hebbian learning

The classical Geiringer theorem addresses the limiting frequency of occurrence of various alleles after repeated application of crossover. It has been adopted to the setting of evolutionary algorithms and, a lot more recently, reinforcement learning and Monte-Carlo tree search methodology to cope with a rather challenging question of action evaluation at the chance nodes. The theorem motivates novel dynamic parallel algorithms that are explicitly described in the current paper for the first time. The algorithms involve independent agents traversing a dynamically constructed directed graph that possibly has loops and multiple edges. A rather elegant and profound category-theoretic model of cognition in biological neural networks developed by a well-known French mathematician, professor Andree Ehresmann jointly with a neurosurgeon, Jan Paul Vanbremeersch over the last thirty years provides a hint at the connection between such algorithms and Hebbian learning.     

Influence of grain boundary weak links on the nonequilibrium response of YBaCuO thin films to short laser pulses

The transient voltage response in both epitaxial and granular YBaCuO thin films to 80 ps pulses of YAGNd laser radiation of wavelength 0.63 and 1.54 m was studied. In the normal and resistive states both types of films demonstrate two components: a nonequilibrium picosecond component and a bolometric nanosecond one. The normalized amplitudes are almost the same for all films. In the superconducting state we observed a kinetic inductive response and two-component shape after integration. The normalized amplitude of the response in granular films is up to five orders of magnitude larger than in epitaxial films. We interpret the nonequilibrium response in terms of a suppression of the order parameter by the excess of quasiparticles followed by the change of resistance in the normal and resistive states or kinetic inductance in the superconducting state. The sharp rise of inductive response in granular films is explained both by a diminishing of the cross section for current percolation through the disordered network of Josephson weak links and by a decrease of condensate density in neighboring regions.