Sequential Data Fusion via Vector Spaces: Fusion of Heterogeneous Data in the Complex Domain

A sequential data fusion approach via higher dimensional vector spaces is introduced. This is achieved by making use of the representation of directional signals within the field of complex numbers $C$ . The concept of data fusion is next introduced and the place of the proposed approach within that framework is identified. The benefits of such an approach are illustrated and a range of possible applications is shown. The concept introduced is supported by a real world case study which focuses on simultaneous forecasting of wind speed and direction. The architectures and learning algorithms which support this concept are introduced and their distributed sequential fusion nature is highlighted.     

Some theoretical aspects of the turbulent point-spread function

In a previous work [J. Opt. Soc. Am. A24, 753 (2007)], we developed a theory describing the space-time statistics of the scintillation and displacement fields of the turbulent point-spread function (PSF), which we validated using imaging data. We now expand on that work by deriving the theoretical expression for the spread fields of the PSF. We also show how the displacement and spread fields are derivable from a set of potentials, and we discuss some of the properties of those potentials.     

The manufacture and performance of diodes made in dielectricallyisolated silicon substrates containing buried metallic layers

Results are reported on the performance of diffused p⁺n diode structures manufactured on a novel silicon-on-metal-on-insulator (SMI) substrate. This substrate consists of a thin single crystal silicon layer on top of a tungsten disilicide covered oxidized silicon wafer. The diodes show excellent characteristics with an exponential current-voltage (I-V) relationship over nine orders of magnitude and an ideality factor of 1.005, under forward bias conditions. The reverse leakage current is low with a minority carrier lifetime of typically 500 μs. The diodes show no evidence of stress induced defects or degraded performance due to W migration during processing. The SMI substrate is therefore shown to be compatible with standard manufacturing processes     

Efficient Join Processing Using Partial Precomputation

In this paper, we generalize conventional join indexes to a cluster-based join index, in which objects are grouped into clusters based on proximity. Each record of our join index represents a pair of clusters in which the join condition is satisfied by some members of the cluster. This strategy is especially useful for spatial and high-dimensional databases because of their typically large data volume and complex operations. Our approach leverages on the structure of R-trees by exploiting the internal nodes of an R-tree in effectively determining the precomputed clusters which can be used in our join index. By varying the size of the cluster, we are able to fine-tune the join index to achieve a balance between update cost and retrieval cost to suit individual applications. Different implementations of the join index are examined to determine how the join index can be efficiently maintained. To this end, we also conduct a number of experiments on intersection join and window queries, and the results confirm that semi-precomputation of join results is a robust and cost effective approach to join processing.     

Synthesis and Properties of Designed Low‐k Fluoro‐Copolyetherimides. Part 1

Polyetherimides are versatile melt‐processable engineering resins. A series of fluoro‐polyetherimides compositions based on diether‐containing diamines were designed on paper and their dielectric constants (ϵ′) estimated before their synthesis. Experimentally determined ϵ′ values were compared with the estimated values. The amorphous polyetherimides containing bis‐trifluoromethyl groups exhibited not only low dielectric constants—lower than those of the commercially available polyetherimide ULTEM 1000 and polyimide Kapton H at 1 kHz—but also excellent long‐term thermo‐oxidative stability and reduced water absorption relative to non‐fluorinated polyimides.     

Revisit the crystallization mechanism of vectra,™ a liquid crystal polymer

We have studied isothermal transition kinetics and crystallization mechanisms of the Hoechst Celanese liquid crystal polymer Vectra™ A‐950 using a differential scanning calorimetry. This material is a random copolymer with a composition made of 73 mol %/27 mol % of HBA (1,4‐dihydroxybenzoic acid)/HNA (2,6‐dihydroxynaphthoic acid). When comparing our results to previous work on 75/25 HBA/HNA, we found some similarities as well as dissimilarities. In the case of similarities, both polymers show two types of transition processes in the low‐temperature region (below 495 K). One is a fast process, which can be regarded as liquid crystal transition, and is characterized by a heat of fusion that does not vary significantly with annealing time. The other transition is a slow process related to crystal perfection and shows increases in the heat of transition and the transition temperature with increasing annealing time. However, the apparently slight difference in polymer composition also leads to a few surprising results. For example, previous work on 75/25 HBA/HNA two transition peaks (slow and fast processes) were observed after annealing it at 505 K, while in the current work only one transition peak in the case of 73/27 HBA/HNA was observed. In addition, based on the relationship between heat of fusion and annealing time, the LCP made from 73/27 HBA/HNA may perfect faster (in the time scale we study); hence, its posttreatment processes may be accomplished more efficiently than that of 75/25 HBA/HNA. This result also suggests that the former may have a better sequence or a better matching of molecular dimensions for crystallization than that of the latter. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1139–1150, 1999     

Synthesis and hydrolysis of β-cyanoethyl ether of poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was cyanoethylated by reaction with acrylonitrile in the presence of sodium hydroxide and quaternary ammonium halide. Quaternary ammonium halide, acting as a phase transfer catalyst, increases the degree of substitution (DS) of PVA. The DS also increased with increasing acrylonitrile concentration. Cyanoethylation of PVA up to 98% can be achieved under optimum conditions. The hydrolysis of β-cyanoethyl ether of PVA (CN–PVA) was studied. The rate of hydrolysis was affected by the sodium hydroxide concentration and the reaction temperature. The rheological properties of aqueous solution of hydrolysis product of CN–PVA were determined at different temperatures, and the flow activation energy was calculated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2771–2777, 1999     

Development and assessment of methods for detecting dementia using the human electroencephalogram

This paper makes an outline case for the need for a low-cost, easy to administer method for detecting dementia within the growing at risk population. It proposes two methods for electroencephalogram (EEG) analysis for detecting dementia that could fulfil such a need. The paper describes a fractal dimension-based method for analyzing the EEG waveforms of subjects with dementia and reports on an assessment which demonstrates that an appropriate fractal dimension measure could achieve 67% sensitivity to probable Alzheimer's disease (as suggested by clinical psychometric testing and EEG findings) with a specificity of 99.9%. An alternative method based on the probability density function of the zero-crossing intervals is shown to achieve 78% sensitivity to probable Alzheimer's disease and an estimated sensitivity to probable Vascular (or mixed) dementia of 35% (as suggested by clinical psychometric testing and EEG findings) with a specificity of 99.9%. This compares well with other studies, reported by the American Academy of Neurology, which typically provide a sensitivity of 81% and specificity of 70%. The EEG recordings used to assess these methods included artefacts and had no a priori selection of elements "suitable for analysis." This approach gives a good prediction of the usefulness of the methods, as they would be used in practice. A total of 39 patients (30 probable Alzheimer's Disease, six Vascular Dementia and three mixed dementia) and 42 healthy volunteers were involved in the study. However, although results from the preliminary evaluation of the methods are promising, there is a need for a more extensive study to validate the methods using EEGs from a larger and more varied patient cohorts with neuroimaging results, to exclude other causes and cognitive scores to correlate results with severity of cognitive status.     

Direct and real-time visualization of the disassembly of a single RecA-DNA-ATPgammaS complex using AFM imaging in fluid

RecA disassembly from circular double-stranded DNA (dsDNA) was studied by atomic force microscopy (AFM) imaging in fluid on a single molecule scale. The RecA/DNA complex was formed in the presence of ATPgammaS, and the disassembly was then initiated by buffer exchange to rinse off ATPgammaS. Performing AFM imaging in fluid allowed direct and real-time visualization of the disassembly of RecA from dsDNA in solution. It was found that RecA disassembly commenced from multiple sites both in deionized water and in buffer; the areas where RecA dissociated showed the appearance of "gaps" in the filamentous structure. RecA further disassembled either through the already existing "gaps" or by generation of new gaps. The disassembly was slower in buffer than in deionized water, suggesting that ions also contribute to the stabilization of the complex. RecA hexamers and monomers were observed in deionized water and in buffer, respectively, during the disassembly process.     

Experimental validation of the MODTRAN 5.3 sea surface radiance model using MIRAMER campaign measurements

Radiometric images taken in mid-wave and long-wave infrared bands are used as a basis for validating a sea surface bidirectional reflectance distribution function (BRDF) being implemented into MODTRAN 5 (Berk et al. [Proc. SPIE5806, 662 (2005)]). The images were obtained during the MIRAMER campaign that took place in May 2008 in the Mediterranean Sea near Toulon, France. When atmosphere radiances are matched at the horizon to remove possible calibration offsets, the implementation of the BRDF in MODTRAN produces good sea surface radiance agreement, usually within 2% and at worst 4% from off-glint azimuthally averaged measurements. Simulations also compare quite favorably to glint measurements. The observed sea radiance deviations between model and measurements are not systematic, and are well within expected experimental uncertainties. This is largely attributed to proper radiative coupling between the surface and the atmosphere implemented using the DISORT multiple scattering algorithm.