Al-Cd Alloy Formation by Aluminum Underpotential Deposition from AlCl3+NaCl Melts on Cadmium Substrate

Aluminum was incorporated into a polycrystalline cadmium electrode surface by underpotential deposition from equimolar AlCl₃+ NaCl melt at 473 K, 523 K, and 573 K (200 °C, 250 °C, and 300 °C). The process was studied by linear sweep voltammetry and potentiostatic deposition/galvanostatic striping. The deposits were characterized X-ray diffraction (XRD), Auger electron spectroscopy (AES), and electron probe microanalyzer (EPMA). The electrochemical measurements showed evidence of Cd-Al alloys being formed but they could not be identified. The growth kinetics of the Cd-Al layers of various proportion and depths that depended on temperature and deposition time were described.     

Optimization of the Use of Basolan DC in the Shrink-resist Treatment of Wool

The influence of Basolan DC applied by an exhaustion treatment on the changes in the mechanical and physico-chemical characteristics of wool fabric is studied by using a central composite rotatable design. The optimum conditions of the treatment are chosen with the use of the polynomial equations obtained, and an optimization diagram is presented. The minimum area shrinkage after washing and the least degradation of wool fibres are obtained with a Basolan DC concentration between 2.5 and 4.5% on the mass of wool and a pH value between 4 and 5.     

Correlation properties of a general binary combiner with memory

Correlation properties of a general binary combiner with an arbitrary number M of memory bits are derived and novel design criteria proposed. For any positive integer m, the sum of the squares of the correlation coefficients between all nonzero linear functions of m successive output bits and all linear functions of the corresponding m successive inputs is shown to be dependent upon a particular combiner, unlike the memoryless combiners. The minimum and maximum values of the correlation sum as well as the necessary and sufficient conditions for them to be achieved are determined. It turns out that the security of combiners with memory can be considerably improved if M is not small.An efficient linear sequential circuit approximation (LSCA) method is developed for obtaining output and input linear functions with comparatively large correlation coefficients which is feasible for large M and works for any practical scheme. The method consists in deriving and solving a linear sequential circuit with additional nonbalanced inputs that is based on linear approximations of the output and the component next-state functions. The corresponding correlation attack on combiners with linear feedback shift registers is analyzed and it is shown that every such combiner with or without memory is essentially zero-order correlation immune.A preliminary version of this paper was presented at Eurocrypt '92 and was published in the proceedings. This research was supported in part by the Science Fund of Serbia, Grant #0403, through the Institute of Mathematics, Serbian Academy of Arts and Sciences.     

General optimal attenuation of harmonic disturbance with unknown frequencies

We present algorithms for optimal harmonic disturbance attenuation in standard discrete-time control structure, based on a parametrisation of (marginally) stabilising controllers. The Frobenius norm and the spectral norm of the closed-loop transfer matrix at the disturbance frequencies are minimised. If there is only one frequency of the disturbance, the controller has an observer–based form, which we obtain by solving a static output feedback (SOF) stabilisation control problem. Although the SOF stabilisation problem is hard, the generical case of nonsquare matrix G ₂₂ is solved by linear algebra methods. Numerical simulation results are presented. As a corollary, we transform the control problem with unit circle invariant zeros into a ?_∞ control problem without such zeros. The elimination of the unit circle invariant zeros is based on the fact that matrix Y(zI???A?+?BF)^?1 is stable, where (Y,?F) with Y?≥?0 is a solution of a discrete-time algebraic Riccati system.     

Structure-preserving numerical algorithm for solving discrete-time LMI and DARS

We present a numerical algorithm to solve a discrete-time linear matrix inequality (LMI) and discrete-time algebraic Riccati system (DARS). With a given system (A,B,C,D) we associate a para-hermitian matrix pencil. Then we transform it by an orthogonal transformation matrix into a block-triangular para-hermitian form. Under either of the two assumptions (1) matrix pair (A,B) is controllable or (2) matrix pair (A,B) is reachable and (A,B,C,D) is a left invertible system, we extract the solution of LMI and DARS by the entries of the orthogonal transformation matrix.     

LQ tracking and disturbance rejecting with invariant zeros on the unit circle

A solution of the problem of optimal linear-quadratic (LQ) tracking and disturbance rejecting with invariant zeros on the unit circle of the plant is given, under a quite general assumption. For that purpose, we transform this problem to a problem of LQ control of an unstabilisable plant by augmentation, and then deal with weakly stabilising controls, defined as the controls such that the unstable modes of the closed-loop system are at most the unstabilisable modes of the augmented pair (A, B).

Then we solve the transformed problem by the newly introduced minimal rank weakly stabilising solution of the most general discrete-time algebraic Riccati system (DARS), associated with the system given by matrix quadruple (A, B, C, D), with unstabilisable matrix pair (A, B).

We show and illustrate by examples that there is a class of LQ tracking problems in the presence of disturbances, which cannot be solved by the existing methods, but can be solved by the introduced minimal rank weakly stabilising solution of the DARS.     

Pyrolysis and Pt(IV)- and Ru(III)-ion catalyzed pyrolysis of asphaltenes in organic geochemical investigation of a biodegraded crude oil (Gaj, Serbia)

This paper is aimed at investigating the origin and geological history of the biodegraded Gaj (Serbia) crude oil, based on comparison of biomarkers, particularly alkylaromatics, in crude oil maltene fraction, with those in the liquid raw asphaltene pyrolysis products. The content of asphaltenes in crude oils being generally very low, expecting a higher yield of pyrolysate, pyrolysis of raw asphaltenes was also carried out in the presence of Pt(IV)- and Ru(III)-ions. The used metal ions demonstrated positive effects on the yields of total liquid pyrolysate and corresponding hydrocarbons. Occluded maltene and asphaltene pyrolysis products showed that metal ions had considerably stronger effect on maturation changes in naphthalene and phenanthrene rings than in polycyclic alkanes. The values of maturity parameters observed in maltenes and pyrolysates suggested this crude oil to have been expelled from the source before the “oil window” maximum. The investigated sample of the Gaj crude oil was shown to be in the 4th stage of biodegradation scale and to have originated from source rocks poor in clays, most probably carbonates, with significant contribution of algae to oil precursor biomass, deposited under a stratified saline water column.     

Relation between Viscous Characteristics and Dextrose Equivalent of Maltodextrins

Relation between viscous characteristics of different maltodextrins and degree of starch hydrolytic conversion expressed as DE value (dextrose equivalent) was deduced. Reduced viscosity of diluted solutions of maltodextrins linearly increased with maltodextrin concentration in the range 0.2×10⁻² to 1×10⁻² g/cm³. Values of intrinsic viscosity decreased with increasing degree of hydrolysis, which is expressed by DE values. Values of intrinsic viscosity of maltodextrins are independent of the botanical source of a particular starch but are dependent on molecular properties of samples that influence its friction characteristics in solution. When in diluted solutions, maltodextrins behave like macromolecules and obey the Staudinger‐Mark‐Houwink equation. Two ranges of DE value were established: DE = 0.5–10, in this range maltodextrin molecules in solution are randomly coiled (a = 0.53); and DE = 10–20, where the molecules are stretched (a = 1). Equations for determination of DE value by viscometric measurements were derived for each of the two established DE ranges. DE values calculated from the equations show good agreement with the ones obtained by standard chemical titration methods.