Analysis and Performance of a Fixed Filter-Thyristor Controlled Reactor (FF-TCR) Compensator

A fixed Filter-Thyristor Controlled Reactor (FF-TCR) type of compensator is proposed to improve the power factor of a single phase thyristor-controlled inductive load and it is shown that this compensator gives better power factor improvement than the more generally used FC-TCR type of compensator. Analysis is carried out for the exact equivalent circuit of an FF-TCR compensator containing two filter branches tuned to the third and the fifth harmonics respectively. It is shown that with an FF-TCR compensator the power factor improvement is much better when the source impedance is large. However, even with a small source impedance, a reasonable improvement in power factor is realised. It is further shown that even when the source impedance is large the distortion in the terminal voltage waveform is kept within reasonable limits. The analytical results are verified experimentally.     

Microprocessor-Based Universal Regulator Using Dual-Rate Sampling

Standard single-rate sampling self-tuning regulators may not be able to effectively control fast-acting systems if the minimum computation time required is larger than the largest sampling period permissible. A dual-rate sampling self-tuning regulator that overcomes this problem by allowing a data sampling rate to be chosen consistent with the system time constants and a control output interval based on the computation time is described in this paper. This algorithm is also very suitable for implementation using fixed word-length processors as the quantization problems are minimized. The algorithm has been implemented on a microprocessor. Implementation details with emphasis on data acquisition, interrupt controlled sampling, time sufficiency test and scaling, and experimental results are also given.     

Adaptive instantaneous pitch detector with microcomputer error correction

A microcomputer is interfaced with an analogue circuit to detect the pitch of voiced speech over a 50 to 500 Hz range in real time.     

Pressure dependence of burning rate of nitrophenolformaldehyde composite propellants

Polymers of o-, m-, and p-nitrophenols with formaldehyde were used as fuel binders in composite propellants based on NH₄ClO₄ and KClO₄ oxidizers. A study of the burning rate in nitrogen has revealed the occurrence of a breakpoint at about 3–5 atm in the burning rate-pressure curves of all six types of composite propellants that contained nitro-substituted phenolic resins as fuel binders.     

Energy utilization in sugarcane production in North India

Average physical and monetary data on sugarcane crops, planted or ratooned, from 128 farms covering 122 ha in North India were transformed into energy equivalents and assessed for energy balance. Farm manure and irrigation consumed major shares. Energy inputs and yields were greatly reduced but energy utilization doubled in ratooned sugarcane. Average energy output-input ratios were about 0.8 and 2.3 for sugar and total biomass, respectively.     

Efficient management of critically important systems

Maintainability of goods producing systems is undertaken on the principles of minimum cost whereas the maintenance of service producing systems is done on the principles of operational reliability. In this paper, theoretical reliability of a service producing system is developed and its application is demonstrated through an actual case history.     

An analysis of the distributions of electronic states associated with hydrogenated amorphous silicon

We study the distributions of conduction band and valence band electronic states associated with hydrogenated amorphous silicon. We find that there are substantial deviations from square-root distributions of electronic states, particularly deep within the bands and within the gap region. We clearly identify where these distributions of electronic states exhibit square-root functional dependencies by fitting square-root functional forms to some experimental data. The corresponding DOS effective masses are determined, and are found to be about 2 to 4 times greater than the crystalline silicon case.     

Einfluß von Legierungselementen auf die Keimbildung von Perlit

Anwendung quantitativer metallographischer Messungen in Verbindung mit statistischen Auswerteverfahren zur Ermittlung der Keimbildungsgeschwindigkeit des Perlits in Legierungen des Eisens mit rd. 0,8 bis 0,9 % C ohne und mit Legierungsanteilen an 2,0% Si, 2,15% Co, 1,15% Cr oder 0,35% Mo. Folgerungen besonders über den Einfluß der Legierungselemente auf die Keimbildungsgeschwindigkeit des Perlits unter Berücksichtigung des Abstandes der Umwandlungstemperatur vom A₁-Punkt.     

Polarographic studies on the coupled product of β-diketones with aryl diazonium chloride

Polarographic reduction of some coupled product of acetyl acetone with aryl diazonium chloride takes place in a single 4-electron transfer, giving a diffusion controlled irreversible waves in B.R. buffers of pH range 2–11.8. The reduction in these compounds takes place at the ---NH---N=C bond. Effect of various cations, anions, surfactant and solvent percentage on the reduction has been discussed.