Supporting complex group decisions: A probabilistic multi-dimensional scaling approach

Groups often face complex decisions; decisions in which the decision alternatives are not clearly defined and the criteria for choosing an alternative are subject to dispute within the group. We present a Group Decision Support System that will use judgments from the group to visualize the decision problem in a probabilistic geometric space. In this geometric representation, actual decision alternatives and an ideal alternative—an artificial alternative that identifies the ideal solution to the group's decision dilemma—are portrayed as distributions in a multi-dimensional space. Dispersions of the distributions measure the uncertainties of the decision process. The psychometric theory used to develop the probabilistic geometric representation is described. Preliminary research is presented which demonstrates that geometric representations of this type help groups both to understand better the decision they face and to find better solutions.     

Quantum Group Symmetry in sine-Gordon and Affine Toda Field Theories on the Half-Line

 We consider the sine-Gordon and affine Toda field theories on the half-line with classically integrable boundary conditions, and show that in the quantum theory a remnant survives of the bulk quantized affine algebra symmetry generated by non-local charges. The paper also develops a general framework for obtaining solutions of the reflection equation by solving an intertwining property for representations of certain coideal subalgebras of U _q (ĝ). Received: 10 December 2001 / Accepted: 7 October 2002 Published online: 19 December 2002     

Regions of nonexistence of invariant tori for spin-orbit models

The spin-orbit problem in celestial mechanics describes the motion of an oblate satellite moving on a Keplerian orbit around a primary body. We apply the conjugate points criterion for the nonexistence of rotational invariant tori. We treat both the conservative case and a case including a dissipative effect modeling a tidal torque generated by internal nonrigidity. As a by-product of the conjugate points criterion we obtain a global view of the dynamics, thanks to the introduction of a tangent orbit indicator, which allows us to discern the dynamical character of the motion.     

A Review of External Pressure Testing Techniques for Shells including a Novel Volume-Control Method

A review of conventional testing methods for applying external hydrostatic pressure to buckling-critical shells is presented. A new “volume-control” pressure testing method, aimed at preventing catastrophic specimen failures and improving control of specimen deformation near the critical load, is also introduced. The implementation of conventional and volume-control systems in an experimental program involving the destructive pressure testing of ring-stiffened cylinders is described. The volume control method was found to improve control of the specimen deformations, especially near the critical load, and catastrophic failures observed while using a conventional setup were avoided. The quasi-static tracking of post-collapse load-deformation relationships for snap-through buckling behaviour was possible while using a volume-control system, but precise control of dynamic shell deformations during buckling was not achieved for specimens failing with large buckling lobes. Expressions for estimating the available control over specimen deformations for pressure testing systems are presented.     

Coexistence of superconductivity and long-range magnetic order in TmRh4B4

Electrical resistance, heat capacity, thermal conductivity and linear thermal expansion coefficient measurements on TmRh₄B₄ indicate that superconductivity and long-range magnetic order coexist in this compound for temperatures less than 0.4 K.     

Application of Fenton‐Based Reactions for Treating Dye Wastewaters: Stability of Sulfonated Azo Dyes in the Presence of Iron(III)

Fenton‐ and photo‐assisted Fenton advanced oxidation processes generate reactive oxygen species from hydrogen peroxide and are candidates for the remediation of dye wastewaters. The purpose of this study was to investigate interactions of iron (III) with hydroxyazo dyes. The o‐hydroxyazo dyes Acid Orange 7 (AO7; 4‐[(2‐hydroxynaphthalen‐1‐yl)azo]benzenesulfonic acid sodium salt) and Acid Orange 10 (AO10; 7‐hydroxy‐8‐(phenylazo)naphthalene‐1,3‐disulfonic acid disodium salt) represent dyes allegedly able to chelate Fe^III through the chromophore. The p‐hydroxyazo dye Acid Orange 20 (AO20; 4‐[(4‐hydroxynaphthalen‐1‐yl)azo]benzenesulfonic acid sodium salt) represents an analogous structure that is unable to chelate Fe^III due to the position of the OH group. Reactions were carried out at pH 2 – 3 in perchlorate or chloride media in the absence of peroxide. No evidence was found by UV/VIS spectroscopy for complexation of Fe^III by the o‐hydroxyazo chromophore. Instead, Fe^III apparently coordinated or formed an ion pair with the sulfonate group, and, when only one sulfonate group was present (i.e., AO7), the dye formed a co‐precipitate with iron(III) hydrous oxides and perchlorate ion. Dye precipitation was seeded by colloidal iron hydrolysis product nuclei. By contrast, the p‐hydroxyazo dye (AO20) was rapidly oxidized by iron(III). The net Fe²⁺/oxidized AO20 ratio was 2 : 1, and a minor yield of 1,4‐naphthoquinone was obtained. The major initial oxidation product, which was not identified, formed a reversible complex with Fe²⁺. Results of this study indicate that the effectiveness of Fenton‐based methods for treating certain azo dyes that form insoluble ferric salts may be compromised by removal of the catalyst from solution. However, the degradation of certain other azo dyes might be assisted by direct thermal oxidation by iron(III).