Optimal Control of a Ship for a Course-Changing Maneuver

The steering control of a ship during a course-changing maneuver is formulated as a Bolza optimal control problem, which is solved via the sequential gradient-restoration algorithm (SGRA). Nonlinear differential equations describing the yaw dynamics of a steering ship are employed as the differential constraints, and both amplitude and slew rate limits on the rudder are imposed. Two performance indices are minimized: one measures the time integral of the squared course deviation between the actual ship course and a target course; the other measures the time integral of the absolute course deviation. Numerical results indicate that a smooth transition from the initial set course to the target course is achievable, with a trade-off between the speed of response and the amount of course angle overshoot.     

Rough set-based logics for multicriteria decision analysis

In this paper, we propose some decision logic languages for rule representation in rough set-based multicriteria analysis. The semantic models of these logics are data tables, each of which is comprised of a finite set of objects described by a finite set of criteria/attributes. The domains of the criteria may have ordinal properties expressing preference scales, while the domains of the attributes may not. The validity, support, and confidence of a rule are defined via its satisfaction in the data table.     

4-Azapteridines. 2. spectral,chromatographic, and X-Ray crystallographic studies concerning the mode of covalent addition to the pyrazino[2,3-e]-as-triazine ring system

The first examples of the unknown pyrazino[2,3-e]-as-triazine ring system, that is, the 6,7-dihydroxy-5,6,7,8-tetrahydropyrazino[2,3-e]-as-triazines, have been prepared by ring closure of selected 5,6-diamino-as-triazines with 40% aqueous glyoxal. These 4-azapteridines experience a novel exchange process with alcohols at the C(7)-position. When dissolved in alcohol and stirred at room temperature, the 7-alkoxy, 6-hydroxy analogues are formed and isolated. In fact, during ring closure, if alcohols are used as the solvent, only the latter compounds are obtained. Initially, cyclization of the ortho-diamino-as-triazines with glyoxal proceeds in a stereoselective manner giving rise to both the cis and trans adducts. A single-crystal X-ray diffraction study has determined the predominant and most stable adduct to be the trans (R,R or S,S) isomer. Spectroscopy (nmr) has verified the intermediacy of the cis adduct, but because of the aforementioned exchange process only the trans isomer is isolated. The site of exchange on these σ-adducts has been rigorously established as C(7). A plausible reaction mechanism by which this exchange process occurs is presented.     

The Studies of the Resonance Raman Scattering and the Chemical Reactions Involved in the Gaseous Iodine Bromide Under Argon Ion Laser Light

The resonance Raman spectra of gaseous iodine bromide IBr have been studied with the excitation of various argon ion laser lines from 5017 to 4579Å. The fine structures of the fundamental and few overtones of IBr are also studied by various power of 4880Å laser line. The resonance Raman scattering is found to be strong as that of Br₂ and ICI. A new term “apparent spectroscopic temperature” is suggusted for the case of the resonance Raman scattering. The apparent spectroscopic temperatures measured in this cell show that the system is not in thermal equilibrium. Br₂ is the hottest and I₂ is the coldest. IBr is in the middle. Unfortunately, no chemical reaction enhanced phenomenon is found although there should be some chemical reactions occurring under the laser light. The initiating reaction is the photodissociation of the main component IBr which also has large absorptivity. Because of the non-crossing between the B³Π and the ¹Π states, the primary products of the photodissociation should be I and Br. The chemical reactions of I and Br with IBr follow. The reactions of I and IBr is endothermic but the reaction of Br with IBr is exothermic. Therefore vibrational hot Br₂ is produced and its apparent spectroscopic temperature should be higher. On the other hand, the apparent spectroscopic temperature of I₂ is lower.     

Syntheses,Structures and Spectroscopic Studies of Silver(I) Coordination Polymers Bridged by Flexible Bidentate Ligands

The reaction of Ag₂SO₄ and bpp (bpp = 1,3‐bis(4‐pyridyl)propane) in H₂O afforded the complex [Ag₂(bpp)₂(SO₄) · 6.5H₂O·CH₃OH]_n, 1. The IR and TGA have been recorded and the structure has been determined. Crystal data for 1: Space group C₂/c, a = 17.885(4), b = 25.230(6), c = 8.832(2) Å, β = 105.437(4)°. V = 3841(1) ų, Z = 8 with final residuals R1 = 0.0710 and wR2 = 0.1620. The complex shows a three‐dimensional supramoleclar structure constructed with two‐dimensional infinite [Ag₂(bpp)₂]_n sheetlike layers pillared by Ag‐Ag interactions and Ag····O (SO₄) interactions in the solid state.     

Insertion reactions of dimethylsilylene: relative reactivity towards oxygenz.sbnd;hydrogen,siliconhydrogen,and siliconz.sbnd;alkoxy bonds

Photochemically-generated dimethylsilylene is found in competition experiments to insert preferentially into oxygenhydrogen bonds of alcohols compared to either siliconhydrogen bonds of silanes or siliconoxygen bonds of alkoxysilanes. This selectivity for OH bonds compared to SiH bonds is quite high in tetrahydrofuran and in dilute hydrocarbon solutions. However, it decreases in more concentrated hydrocarbon solutions. These effects are discussed in terms of aggregation of alcohols, hydrogen bonding, and solvent-mediated dimethylsilylene reactivity.     

Muttiphoton Ionization of Benzene-Ammonia Clusters: Intracluster Reaction and Cluster Ion Stability

Neutral benzene-ammonia clusters, prepared in a supersonic expansion, were ionized using multiphoton ionization. The cluster ions were investigated with a time-of-flight mass spectrometer. The observed major cluster ions, under 355-nm laser irradiation, resulting from prompt intracluster ion-molecule reaction and fragmentation following ionization are (C₆H₆)_m(NH₃)_nH⁺, m = 1–6, n = 1–4 and (C₆H₆)_m⁺, m = 1–3. The results of isotopic labeling experiments clearly indicate that C₆H₆ does not participate in intracluster ion-molecule reactions to form (C₆H₆)_m(NH₃)_nH⁺. A local maximum appears at n = 2 in the intensity distribution of (C₆H₆)_m(NH₃) _nH⁺ for each value of m under all experimental conditions. This finding indicates that (C₆H₆)_m(NH₃)₂H⁺ is more stable than any other (C₆H₅)_m(NH₃)_mH⁺ (n = 1,3,4) for m = 1–6.