The multicomponent AM-FM image representation.

We compute AM-FM representations for multicomponent, nonstationary images using a statistical component model. Components are isolated with a filterbank comprising frequency and orientation selective channels. The modulating functions for each component are estimated from the channel responses using localized nonlinear operators followed by optimal MMSE estimators. We also demonstrate reconstruction from the representation.     

Properties of the magnitude terms of orthogonal scaling functions

The spectrum of the convolution of two continuous functions can be determined as the continuous Fourier transform of the cross-correlation function. The same can be said about the spectrum of the convolution of two infinite discrete sequences, which can be determined as the discrete time Fourier transform of the cross-correlation function of the two sequences. In current digital signal processing, the spectrum of the continuous Fourier transform and the discrete time Fourier transform are approximately determined by numerical integration or by densely taking the discrete Fourier transform. It has been shown that all three transforms share many analogous properties. In this paper we will show another useful property of determining the spectrum terms of the convolution of two finite length sequences by determining the discrete Fourier transform of the modified cross-correlation function. In addition, two properties of the magnitude terms of orthogonal wavelet scaling functions are developed. These properties are used as constraints for an exhaustive search to determine a robust lower bound on conjoint localization of orthogonal scaling functions.     

PARTITION CHROMATOGRAPHY OF SUGARS IN WORT AND BEER ON ANION EXCHANGE RESINS

Partition chromatography on anion exchange resins in the sulphate form in 85% ethanol at 75°C was used for the separation of monosaccharides in beer and wort. The eluate was analysed automatically by the orcinol method. Simultaneous analysis by a periodate-formaldehyde method permitted determination of glycerol. Oligomers, except for those precipitated by 65% ethanol, were separated and characterized by chromatography in this medium. Sharp separations of disaccharides were made at an intermediate concentration. Species which were not separated on this resin were resolved on a cation exchanger in its lithium form. The identification of oligomers was facilitated by the fact that for oligomers having the same type of glycosidic bonds there exists a straight line relationship between the logarithm of the distribution coefficient and the number of monosaccharide residues.     

A Genetic Programming Approach to System Identification of Rainfall-Runoff Models

Advancements in data acquisition, storage and retrieval are progressing at an extraordinary rate, whereas the same in the field of knowledge extraction from data is yet to be accomplished. The challenges associated with hydrological datasets, including complexity, non-linearity and multicollinearity, motivate the use of machine learning to build hydrological models. Increasing global climate change and urbanization call for better understanding of altered rainfall-runoff processes. There is a requirement that models are intelligible estimates of underlying physics, coupling explanatory and predictive components, maintaining parsimony and accuracy. Genetic Programming, an evolutionary computation technique has been used for short-term prediction and forecast in the field of hydrology. Advancing data science in hydrology can be achieved by tapping the full potential of GP in defining an evolutionary flexible modelling framework that balances prior information, simulation accuracy and strategy for future uncertainty. As a preliminary step, GP is used in conjunction with a conceptual rainfall-runoff model to solve model configuration problem. Two datasets belonging to a tropical catchment of Singapore and a temperate catchment of South Island, New Zealand with contrasting characteristics are analyzed in this study. The results indicate that proposed approach successfully combines the merits of evolutionary algorithm and conceptual knowledge in the generation of optimal model structure and associated parameters to capture runoff dynamics of catchments.     

Limits on discrete modulated signals

We develop theorems of a general nature that apply to the analysis of AM-FM signals of the form a(m)exp [jφ(m)] or a(m) cos [φ(m)] and to their behavior both in linear systems and in simple nonlinear systems comprised of products of linear elements. Such product-systems include interesting nonlinear demodulation operators, such as the Teager-Kaiser (1990) operator. Expressions for the approximate system responses to AM-FM signals are derived by making an analogy to the eigenfunction interpretation of sinusoids in linear systems; for the case of sinusoidal signals, the approximations are exact. These expressions are collectively called quasieigenfunction approximations (QEAs). For nonsinusoidal AM-FM signals, the approximations have errors that are tightly bounded by functionals that express the smoothness of the AM and FM information signals and the durations of the involved system impulse responses. The bounds are independent of the bandwidths of the AM and FM functions. Two general applications are considered. First, the approximations are found to be useful for analyzing discrete-time nonlinear energy operators, including the Teager-Kaiser operator. Next, the approximation theorems lead to the selection of an optimal class of bandpass filters for use in a discrete multiband AM-FM demodulation system. The filter class selected is optimal in the sense of achieving the lower bound of a novel discrete uncertainty principle     

Multicomponent Multidimensional Signals

In this brief paper, we extend the notion of multicomponent signal into multiple dimensions. A definition for multidimensional instantaneous bandwidth is presented and used to develop criteria for determining the multicomponent nature of a signal. We demonstrate application of the criteria by testing the validity of a multicomponent interpretation for a complicated nonstationary texture image.     

The Role of Heteroatoms Leading to Hydrogen Bonds in View of Extended Chemical Stability of Organic Semiconductors

The major challenge in organic electronics concerns the stability of organic semiconductor materials which affects the operational lifetime of devices. Recent reports have shown that hydrogen‐bonded pigments of the indigoid family are air‐ and moisture resistant. The magenta pigment quinacridone, a hydrogen‐bonded molecule in the solid state with a pentacene like frame, is a perfect example for extraordinary chemical stability. Here, studies using in situ spectroscopic methods comparing quinacridone and pentacene are presented. A different spectral response of their radical cations is observed upon chemical doping. While in pentacene the barrier between doping and irreversible overoxidation is small, this stability toward overoxidation is increased by the heteroatomic structure, leading to hydrogen‐bonded quinacridone. This work provides insight into molecular design principles that may lead to next‐generation organic semiconductors with enhanced stability and performance.     

COPERM: transform-domain energy compaction by optimal permutation

Compaction by optimal permutation (COPERM) is a tool for transform domain energy compaction of broadband signals, whose foundation is a simple but powerful idea: any signal can be transformed to resemble a more desirable (e.g., from a transform-domain compaction viewpoint) signal from a class of “target” signals (e.g., DCT basis functions) by means of a suitable permutation of its samples. One application of transform-domain energy compaction is in lossy compression. We pursue one possible thread in detail and demonstrate some interesting broadband image compression results     

Multidimensional orthogonal FM transforms

The present a novel class of multidimensional orthogonal FM transforms. The analysis suggests a novel signal-adaptive FM transform possessing interesting energy compaction properties. We show that the proposed signal-adaptive FM transform produces point spectra for multidimensional signals with uniformly distributed samples. This suggests that the proposed transform is suitable for energy compaction and subsequent coding of broadband signals and images that locally exhibit significant level diversity. We illustrate these concepts with simulation experiments.