Personal Computer Simulation Program for Step Motor Drive Systems

A system of equations modeling a class of step motors known as the permanent magnet rotor step motor is presented. The model is implemented on a APPLE personal computer in a version of BASIC. Measurements are then made on an existing motor and input to the program for validation. A special test fixture is utilized to take performance data on the motor to facilitate comparisons with the predictions of the program. The comparisons show the model is indeed valid for design of step motor drive systems and emphasize the practical nature of using personal computers and simulations for design

Novel Methods for Modern NMR Spectroscopy - Optimized Pulses and New Experiments

Die NMR-Spektroskopie verdankt ihre Flexibilität der Vielzahl möglicher NMR-Experimente. Im Rahmen dieser Arbeit wurden NMR Pulse, die Bausteine der Experimente, mit Methoden der Optimal Control Theory optimiert und mehrere neue Experimente entwickelt: Das CLIP-COSY, ein homonukleares Korrelationsexperiment, wird vorgestellt. Verbesserungen und theoretische Betrachtungen zum ASAP-HSQC, einem heteronuklearen Korrelationsexperiment, werden beschrieben. Abschließend werden Experimente zur Analyse inhomogener und anisotroper Proben, die die Messung von RDCs vereinfachen, präsentiert

Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

The Grignard reaction of 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside and benzylmagnesium chloride (or bromide) afforded a non-separable mixture of diastereomeric benzyl carbinols and diastereomeric o-tolyl carbinols. The latter resulted from an unexpected benzyl to o-tolyl rearrangement. The proportion of benzyl versus o-tolyl derivatives depended on the reaction conditions. Benzylmagnesium chloride afforded predominantly o-tolyl carbinols while the application of benzylmagnesium bromide led preferably to the o-tolyl carbinols only when used in excess or at higher temperatures. The structures of the benzyl and o-tolyl derivatives were confirmed unambiguously by NMR spectral data and X-ray crystallographic analysis of their 5-ketone analogues obtained by oxidation of the corresponding mixture of diastereomeric carbinols. A possible mechanism for the Grignard reaction leading to the benzyl -> o-tolyl rearrangement is also proposed

The Kazhdan-Lusztig conjecture for W-algebras

The main result in this paper is the character formula for arbitrary irreducible highest weight modules of W algebras. The key ingredient is the functor provided by quantum Hamiltonian reduction, that constructs the W algebras from affine Kac-Moody algebras and in a similar fashion W modules from KM modules. Assuming certain properties of this functor, the W characters are subsequently derived from the Kazhdan-Lusztig conjecture for KM algebras. The result can be formulated in terms of a double coset of the Weyl group of the KM algebra: the Hasse diagrams give the embedding diagrams of the Verma modules and the Kazhdan-Lusztig polynomials give the multiplicities in the characters.Comment: uuencoded file, 29 pages latex, 5 figure

DAC-Less amplifier-less generation and transmission of QAM signals using sub-volt silicon-organic hybrid modulators

We demonstrate generation and transmission of optical signals by directly interfacing highly efficient silicon-organic hybrid (SOH) modulators to binary output ports of a field-programmable gate array. Using an SOH Mach-Zehnder modulator (MZM) and an SOH IQ modulator we generate ON-OFF- keying and binary phase-shift keying signals as well as quadrature phase-shift keying and 16-state quadrature amplitude modulation (16QAM) formats. Peak-to-peak voltages amount to only 0.27 V-pp for driving the MZM and 0.41 V-pp for the IQ modulator. Neither digital-to-analog converters nor drive amplifiers are required, and the RF energy consumption in the modulator amounts to record-low 18 fJ/bit for 16QAM signaling

Game theory and its practical applications

Game theory identifies players\u27 optimal strategies in the face of interdependence and uncertainty . Games can be divided into two-person and n-person games, zero-sum and nonzero-sum games, and cooperative and non-cooperative games. Although this paper does not touch upon all of these aspects of game theory, it does offer a nice introduction of game theory and its applications for those who are not mathematical specialists