Magnetic Thomas-Fermi-Weizsäcker model for quantum dots: A comparison with Kohn-Sham ground states

The magnetic extension of the Thomas-Fermi-Weizs?cker kinetic energy is used within density-functional-theory to numerically obtain the ground state densities and energies of two-dimensional quantum dots. The results are thoroughly compared with the microscopic Kohn-Sham ones in order to assess the validity of the semiclassical method. Circular as well as deformed systems are considered. Received 26 October 2000 and Received in final form 14 December 2000     

An efficient solver for weighted Max-SAT

We present a new branch and bound algorithm for weighted Max-SAT, called Lazy which incorporates original data structures and inference rules, as well as a lower bound of better quality. We provide experimental evidence that our solver is very competitive and outperforms some of the best performing Max-SAT and weighted Max-SAT solvers on a wide range of instances.     

MV-Algebra for Cultural Rules

This paper reports preliminary results on a new area of application of quantum structures, motivated by a reading of the 2004 monograph Reasoning in Quantum Theory. Ethnographers often describe a particular culture by describing rules of social relations that they assert characterize that culture. Viable cultures exist over periods of time, that is, over sequences of “generations”. To embody this, we define a suitable set of objects and relations, and a structure on which cultural rules act as “operators” on a set of “configurations” on generations. This yields an MV-algebra of those operators. This implies that culture theory might be studied as an example of the theory of quantum structures. The author acknowledges Dick Greechie in appreciation for the many comments he offered on this paper and on the development of this line of research. Useful comments of an unidentified reviewer helped clarify results. Only the author is responsible for any errors, and for the ideas asserted. This paper was delivered at the meetings of the International Quantum Structures Association, IQSA-Malta 2006.     

Dynamics of coupled systems

A survey in the form of a review of the author’s research results in the area of dynamics of coupled rotations and coupled systems is presented. The theorem on the existence of a trigger of the coupled singularities and the separatrix in the form of the number eight is presented with a few examples of coupled rotations of the simple systems with debalances. Also, a survey of models and dynamics of coupled systems composed of a number of deformable bodies (plates, beams or belts) with different properties of materials and discrete layer properties is presented and mathematically described. The constitutive stress–strain relations for materials of the coupled sandwich structure elements are presented for different properties: elastic, viscoelastic and creeping. The characteristic modes of the coupled system vibrations are obtained and analyzed for different kinds of materials and structure composition. The visualization of the characteristic numbers and modes and eigenamplitude forms are presented. Structural analysis of sandwich structure vibrations is done.     

Syntheses, crystal structure and spectroscopic characterization of new platinum(II) dithiocarbimato complexes

The reaction of 4-iodobenzenesulfonamide or 4-fluorobenzenesulfonamide with CS₂ and KOH in dimethylformamide yielded the potassium N-R-sulfonyldithiocarbimates, K₂(RSO₂NCS₂) [R = 4-IC₆H₄ (1) and 4-FC₆H₄ (2)]. These salts reacted with K₂[PtCl₄] in water/methanol to yield complex anions bis(N-R-sulfonyldithiocarbimato)platinate(II), which were isolated as their tetrabutylammonium salts, (Bu₄N)₂[Pt(RSO₂NCS₂)₂] [R = 4-IC₆H₄ (3) and 4-FC₆H₄ (4)]. The structures of 2–4 were determined by X-ray crystallography. The Pt²⁺ in both complexes 3 and 4 lies at the inversion centre and the PtS₄ moiety has a distorted square-planar configuration. The compounds were also characterized by IR, ¹H NMR and ¹³C NMR spectroscopies, and elemental analyses. The molar conductance data are consistent with the fact that 3 and 4 are dianionic complexes.     

Designing information structures for quadratic decision problems

This paper investigates the problem of unconstrained optimization when there is only partial information on the random parameters in the objective function. The relation between the optimization performance and the available information is established. The best information structure design with fixed rank is described. The designing procedure is set up in such a way that successive information augmentation or deletion can be considered. The procedure can also be extended to multiperson decision problems.     

Diffusion and reaction in random media and models of evolution processes

A diffusion equation including source terms, representing randomly distributed sources and sinks is considered. For quasilinear growth rates the eigenvalue problem is equivalent to that of the quantum mechanical motion of electrons in random fields. Correspondingly there exist localized and extended density distributions dependent on the statistics of the random field and on the dimension of the space. Besides applications in physics (nonequilibrium processes in pumped disordered solid materials) a new evolution model is discussed which considers evolution as hill climbing in a random landscape.We dedicate this work to the memory of Ilya M. Lifshitz.     

Robust inverse optimal control for flexible structures

An inverse optimal control problem is formulated to develop robust control laws for purely oscillatory systems. The optimal control solution requires output feedback with specified constraints, leading to robustness with respect to unmodeled modes and a large class of parameter variations. The robustness properties are proved directly from known properties of control laws resulting from quadratic performance indices. The control laws are useful for poorly damped flexible structures.This research was supported by the Office of Naval Research, Contract No. N00014-77-C-0247.     

Mode structure in wideband waveguide radiofrequency CO2 lasers

We have analysed the mode structure of a wideband radiofrequency excited waveguide CO₂ laser by using different waveguide diameters and optical cavities. In particular we have observed the phase shift of some linear polarized waveguide modes in the transition region between the guided and the free Gaussian propagation.