Electromotive Force

What is reactance? In electricity, measure of the opposition that a circuit or a part of a circuit presents to electric current insofar as the current is varying or alternating is called reactance. Greater reactance gives smaller current for the same applied voltage. Reactance is similar to resistance in this respect, but differs in that reactance does not lead to dissipation of electrical energy as heat. Instead, energy is stored in the reactance, and a quarter-cycle later returned to the circuit, whereas a resistance continuously loses energy. The reactance is to change in any current, not just AC.

This paper presents a general proposal to design and calculate the performance of a tubular permanent magnet linear generator using the Finite Element Method, The cogging force, which occurs due to the interaction between stator teeth and the permanent magnets, is reduced by optimizing the linear generator dimensions. The generated voltage is analyzed for both no load and load cases to take the armature reaction effects on the air gap flux density. A repetitive routine is followed to calculate the output voltage from the change afflux and the speed of the generator. The output voltage is calculated for different resistive loads, and hence the generator load characteristic is obtained. The designed linear generator is capable to generate an output power of 5.3kW with output voltage of 222V and the generator efficiency of 96.8%. © 2004 IEEE.

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1374629

We propose a dynamical theory of how the chemical energy stored in a battery generates the electromotive force (emf). In this picture, the battery's half-cell acts as an engine, cyclically extracting work from its underlying chemical disequilibrium. We show that the double layer at the electrode-electrolyte interface can exhibit a rapid self-oscillation that pumps an electric current, thus accounting for the persistent conversion of chemical energy into electrical work equal to the emf times the separated charge. We suggest a connection between this mechanism and the slow self-oscillations observed in various electrochemical cells, including batteries, as well as the enhancement of the current observed when ultrasound is applied to the half-cell. Finally, we propose more direct experimental tests of the predictions of this dynamical theory.

The complex species formed between vanadium(III) and 1,10-phenanthroline (phen), 2,2′-bipyridine (bipy), and 8-hydroxyquinoline (8hq) were studied in aqueous solution by means of electromotive forces measurements, emf(H), at 25 °C with 3.0 mol⋅dm−3 KCl as the ionic medium. The potentiometric data were analyzed using the least-squares computational program LETAGROP, taking into account the hydrolytic vanadium(III) species formed in solution. Analysis of the vanadium(III)–phen system data shows the formation of [VHL]4+, [V(OH)L]2+, [V2OL2]4+ and [V2OL4]4+ complexes. In the vanadium(III)–bipy system the [VHL]4+, [V(OH)L]2+, [V2OL2]4+ and [V2OL4]4+ complexes were observed, and in the vanadium(III)–8hq system the complexes [V(OH)L]+, [V(OH)2L], [VL2]+ and [VL3] were detected.

Modeling of multi-phase PMSM has been widely studied in the literature. Nevertheless, the methods applied for this achievement are complex due to the strong need to do an analysis of the magnetic field distribution inside the machine. In addition, mathematical transformations and calculations are required to implement such models. In the proposed study, a new modeling method is proposed based on a very simple theoretical computation approach with high accuracy. Its importance is that the model created will be used to do a fault tolerant control for the machine under study. The methodology is explained and presented first, the model is then simulated using the Matlab/Simulink software and finally validated by experimental tests using various topologies and hazards of electrical networks connected to the machine phases.

In this work, the mean activity coefficient of NiCl 2 in the (NiCl 2 + NiSO 4 + H 2 O) mixed electrolyte system were determined by using the potentiometric technique at T = 298.15 K. The measurements were carried out on the galvanic cell without liquid junction of the type: Ni–ISE/NiCl 2 (m A ...

The thermodynamic properties of liquid (Sb + Sn) and (Au + Sb + Sn) alloys were determined using solid oxide galvanic cells with zirconia electrolyte: Re þ kanthal;Sb x À Sn ð1ÀxÞ ; SnO 2 ==ZrO 2 þ ðY 2 O 3 Þ==NiO; Ni; Pt; ðIÞ Re þ kanthal;Au x À Sb y À Sn ð1ÀxÀyÞ ; SnO 2 ==ZrO 2 þ ðY 2 O 3 Þ==NiO; Ni; Pt; ðIIÞ over the temperature range from (973 to 1273) K. Using the Gibbs free energy of formation of pure solid tin oxide SnO 2 , at first the activities of tin were determined in the binary (Sb + Sn) system. Next, measurements were conducted in the ternary (Au + Sb + Sn) system along two cross-sections specified by the ratio of mole fractions x Au /x Sb = 1:2 and 2:1. Thermodynamic properties of the liquid phase were described by the Redlich-Kister-Muggianu formula. In this procedure, the heat of mixing determined in our previous paper was included. The results of the calculations were compared with the experimental values obtained for this system.