Detection and Validation of Clusters of Polynomial Zeros

We consider the task of partitioning the zeros of a real or complex polynomial into clusters and of determining their location and multiplicity for polynomials with coefficients of limited accuracy. We derive computational procedures for the solution of this task which combine symbolic computation with floating-point arithmetic. The validation of the existence ofmzeros in a specified small disk is described.     

Kinetic study of the hydrolysis of isocyanic acid in the gas phase

The hydrolysis of isocyanic acid in the gaseous phase has been investigated at temperatures between 553 and 613 K by mass spectrometry and evaluated to obtain the corresponding kinetic data. The reaction order and reaction constant have been determined. Finally, the influence of water on the catalysed formation of melamine from isocyanic acid under the operating conditions employed has been investigated in order to determine whether there is a need to try the process gas.     

Transient and dynamic average-value modeling of synchronous machinefed load-commutated converters

A new average-value model of a synchronous machine fed load-commutated converter is set forth in which the stator dynamics are combined with the DC link dynamics. This model is shown to he extremely accurate in predicting system transients and in predicting frequency-domain characteristics such as the impedance looking into the synchronous machine fed load-commutated converter. The model is verified against a detailed computer simulation and against a hardware test system, thus providing a three-way comparison. The proposed model is shown to be much more accurate than models in which the stator dynamics are neglected     

Zu einem Phänomen der Lochkorrosionsbegrenzung bei hochlegierten Sonderedelstählen und NiCrMo-Legierungen in Chloridlösungen

On a phenomenon of the limitation of pitting corrosion at high alloyed special stainless steels and NiCrMo-alloys in chloride solutions Testing the pitting corrosion resistance of high alloyed special stainless steels and NiCrMo-alloys in chloride solutions there was observed a limitation of the pitting corrosion range toward more positive potentials. Above this limitation, the so-called pitting corrosion limitation potential, the pit initiation by all means is prevented, but the growth of pits which had been initiated before in the pitting corrosion range not necessarily comes to a stop. Therefore current density-potential curves which are obtained by downward polarization after an initial potential jump into the transpassive region and chronopotentiostatic tests are more suitable to investigate this phenomenon than cyclic polarization measurements and potentiostatic alteration tests. There is indicated a dependence of this phenomenon on temperature. The phenomenon of a limitation of the pitting corrosion range toward more positive potentials has been found until now at alloy 926, alloy 31, alloy 28, alloy 59 and alloy C-276.     

Power engineering industry interaction at Clemson University

The authors present a successful model of industry/university cooperation in establishing a strong power system curriculum in both the graduate and undergraduate level. Numerous long-term and short-term research projects have been developed to satisfy the university mission and to tackle challenging problems facing the power industry. A unique structure for the Clemson University Electric Power Research Association (CUEPRA) has been established to promote electric power system research and to meet the need for a working communication link between the power industry and the academic community. The power industries involvements in the power program at Clemson University and the strategic improvements that have been accomplished in research and education are outlined     

Development of improved methods for type testing present day mediumvoltage circuit breakers for outdoor service

Type testing for fault currents for medium-voltage circuit breakers rated at 15 kV to 72.5 kV is addressed. The ANSI designation of a new class of definite-purpose circuit breakers capable of switching transformer secondary faults and the introduction of the requirement for short-line-fault tests for breakers rated 72.5 kV and below have increased the difficulty of performing type tests in a testing laboratory. It is concluded that synthetic testing using the parallel current injection circuit is described in ANSI C37.081 provides the best available method for proving these complex requirements for medium-voltage circuit breakers