Effect of series compensation on the voltage instability of EHV long lines

In this paper, the effects of the operating conditions and dynamic performance on the voltage instability phenomena of EHV lines with series compensation is discussed. Exponential modelling of loads and exact long-line equations are used in the analysis. Graphs showing the variations of the receiving-end voltage and the transformer tap ratio with time for an assumed load variation are given. It is shown that when series compensation is provided, the chances of voltage instability occurring are less. The effect of switched series compensation on the voltage instability is also investigated. The error in using short-line equations for the analysis of voltage instability phenomena is highlighted. The random loading conditions of the system and the random load parameter variations are also considered for the first time in analysing the voltage instability phenomenon.     

Measurement of individual differences in preference for numerical information.

Develops and validates a measure of preference for numerical information, defined as a proclivity toward using numerical information and engaging in thinking involving numerical information, and assesses the relationship of this construct to several constructs. Although past research has focused on ability in using numerical information, a basic attitude or proclivity toward numerical information has not been isolated and studied. This construct is argued to have applications in settings that involve the use of numerical information and to be related to several interests, temperaments, and cognitive styles. A measure of preference for numerical information is developed and tested for reliability and validity, its relationship with several constructs is examined, and its applications in various settings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dilatometric technique for evaluation of the kinetics of solid-state transformation of maraging steel

Solid-state transformation kinetics of a 350 grade commercial maraging steel were investigated using a nonisothermal dilatometric technique. Two solid-state reactions—namely, precipitation of intermetallic phases from supersaturated martensite and reversion of martensite to austenite—were identified. Determination was made of the temperatures at which the rates of these reactions reached a maximum at different heating rates. The kinetics of the individual reactions in terms of activation energy were analyzed by simplified procedures based on the Kissinger equation. An estimated activation energy of 145 ± 4 kJ/mol for the precipitation of intermetallic phases was in good agreement with reported results based on the isothermal hardness measurement technique. Martensite to austenite reversion was associated with an activation energy of 224 ± 4 kJ/mol, which is very close to the activation energy for diffusion of substitutional elements in ferrite. Results were supplemented with microstructural analysis.     

Diversity combining in FH/BFSK systems to combat partial bandjamming

A combiner for a frequency-hopped binary frequency-shift keyed (FH/BFSK) system, called the product-combining receiver (PCR), is introduced. The performance of the PCR is evaluated for the cases of an on/off partial-band noise with optimum-jamming fraction, and worst-case, partial-band tone jamming. The performance of PCR is shown to be comparable to that of the clipper receiver. The effect of diversity combining, along with convolutional coding and ratio-threshold technique, is analyzed. Whereas the clipper requires the knowledge of signal-to-noise ratio for threshold adjustments, the PCR does not require this knowledge for this operation     

Superconductivity in irradiated A-15 compounds at low fluences. I. Neutron-irradiated V3Si

The behavior of the superconducting transition temperature T _c of singlecrystal and polycrystalline V₃Si was investigated as a function of low-fluence neutron irradiation. It is found that the initial degradation of T _c is sample-dependent, some specimens showing no degradation in T _c up to a fluence of 2 × 10¹⁸ n/cm². This and many other earlier observations on low-fluence behavior are explained in terms of a recently proposed model of radiation damage in A-15 compounds.Work performed under the auspices of the U.S. Energy Research and Development Administration.     

Synthesis, kinetic observations and characteristics of polyarylene ether sulphones prepared via a potassium carbonate DMAC process

The classical route for the synthesis of this family of macromolecules is via nucleophilic aromatic substitution of 4,4′-dichlorodiphenyl sulphone with bisphenates using dimethylsulphoxide (DMSO) and aqueous sodium hydroxide. High molecular weight homopolymers can be synthesized in a relatively short time. However, hydrolytic side reactions can limit its scope for the synthesis of both homopolymers derived from insoluble bisphenates and for copolymers. An alternate route is discussed herein that uses potassium carbonate/dimethylacetamide as base and aprotic dipolar solvent, respectively, for the synthesis of several homopolymers and copolymers derived from various bisphenols. In this system, excess potassium carbonate, unlike aqueous caustic, does not prevent the synthesis of high molecular weight macromolecules. Investigations of the kinetics and mechanism of this process were conducted. These studies demonstrated that this route deviates from the relatively simple second order kinetics previously observed for the aqueous sodium hydroxide/DMSO system. This deviation has been rationalized as resulting from the partially heterogeneous nature of the potassium carbonate.     

Persistency of excitation for nonminimal models of systems having purely deterministic disturbances

All results to date on the question of persistency of excitation depend on the model being minimal. Thus the results do not apply to systems having purely deterministic disturbances since these automatically give rise to uncontrollable modes on the unil circle. This note presents new results on persistency of excitation applicable to nonminimal models of systems having purely deterministic disturbances.     

A three-dimensional approach to the electrolytic degradation of solid electrolytes

A semiquantitative three-dimensional analysis of the electrolytic degradation of solid electrolytes is presented. This analysis leads to critical current densities that are in accord with experimental observations in contrast with the two-dimensional models which lead to a discrepancy of three orders of magnitude. The effect of microstructure has also been incorporated into the analysis.     

Martensitic transformations in V3Ga and Nb3Al

It is shown by low-temperature heat capacity measurements using ac technique that martensitic transformation in small samples of V₃Ga and Nb₃A1 can be prevented by covering them nearly completely with copper plating.