Current variation

Figure 14-4A. Oscillogram shows variation of current to a synchronous motor driving a reciprocating compressor, The compressor is two-cylinder, horizontal, double-acting, and operates at 257 rpm. Line A is the envelope of the current wave. Difference B-C is current variation. Value B-C divided by the rated full load current is the percentage of current variation. (Used by permission Oscarson, G. L. E-M Synchronizer, 200 SYN 52, p. 11. Dresser-Rand Company.)...

Miniaturisation of electronic components has enabled the construction of a compact, portable, battery-operated recording voltmeter. The principal use of this instrument is to measure pipe/soil potential fluctuations over a period of time. The instrument can be modihed to measure current variations. 

For the individual types of transient measuring techniques, special names exist but their terminology lacks uniformity. The potentiostatic techniques where the time-dependent current variation is determined are often called chronoamperometric, and the galvanostatic techniques where the potential variation is determined are called chronopotentiometric. For the potentiodynamic method involving linear potential scans, the term voltammetry is used, but this term is often used for other transient methods as well. 

In a Boost topology, there are no edges of inductor current waveform at the input. That is because there is an inductor present in series with the input, which helps level any current variations. So though a certain (small) amount of bulk capacitance is still required to smooth out the slowly undulating inductor current further, in principle, high-frequency... 

Figure 25. Schematic illustration of current variation and coverage of silicon oxide on the surface of a pore bottom.

The most striking feature of the peak or plateau current variation with substrate concentration is that the initial, and expected, increase is followed be a strong decrease that eventually annihilates catalysis. This decrease results from inhibition by the substrate, H202, which converts the E2 complex in the complex E3. E3 is the iron(II) dioxygen complex classically considered in dioxygen transport. It may regenerate E spontaneously by expulsion of the superoxide ion. This process is, however, very slow and the most important regeneration pathway involves the cosubstrate as pictured in Scheme 5.3. 

Figure 7. Conductivity map of KTP showing the ionic current variation over the wafer.

In chronoamperometry, which is employed in a few electronic tongue systems (Cortina et al., 2008 Han et al., 2004), the potential is kept constant, while the current variations, resulting from faradic processes occurring at the electrode, are monitored as a function of time. 

Cyclic voltammograms were also performed with platinum microelectrodes on skin surface at regular time intervals of about 7 h. Figure 8.10 shows the typical curve giving the evolution of the anodic current at 0.9V/SCE as a function of time. A sinusoidal evolution was observed for the nine volunteers. Current values as well as the amplitude and the period of the variations were different for each subject. It has been verified that the amplitude of the current variations was significantly higher than the accuracy of the amperometric response. Consequently, the variation of the anodic current was actually due to a variation of the oxido-reductive properties of the skin and was not an artifact of the measurements. 

In STM, image contrast is derived from spatial variations in current flowing between the proximal probe and the sample.126 Tunneling in an STM relies on the spatial overlap of the tip and sample electronic orbitals. Therefore, the tunneling current falls off very rapidly (on atomic length scales) as a function of distance between the tip and a particular sample feature such as an isolated atom. Tunneling current variations and information on surface chemistry are specifically derived from the associated atomic-scale variations in the density of states near the sample surface. 

Figure 3. Photo scanning of plasma radiation intensity at 44 kHz frequency during one period of current. Corresponding graph of current variation is shown below. Scheme of electrodes positioning is shown on the right, r - distance between electrodes, I - current t -time.

Scroggs RS, Fox AP (1992) Calcium current variation between acutely isolated adult rat dorsal root ganglion neurons of different size. J Physiol 445 639-658... 

Arrangements of atoms on the surface of a crystal can be determined. Surface species and the nature of bonding of these can be studied by examining voltage-current variations during scanning... 

Two Radio-Corporation amplifiers (CX 371 A) with a filament temperature of about 800° C. are used as a source of current. Variations of temperature have very little effect on the frequency. The gas-filled condenser Co is compared with a condenser Cl (filled with nitrogen) of exactly the same construction. Each condenser consists of nine heavily gilt precision cylinders with a total capacity of 2070 cm. The gas and air condensers are fitted into a metal boiler in a bath of about 50 litres of paraffin oil. The range of temperature of the bath is from room temperature to about 300° C. A quartz compensation manometer connected with the boiler by an invar-quartz joint enables the pressure of the gas to be measured correct to i/io mm. One side of... 

The sample positioned in the magnetic field is, in addition, surrounded by a coil of several turns (cf. Fig. 13.3 ). An alternating current of gradually varying frequency runs through this coil. On resonance, the transmitter transfers the energy to the spin system, resulting in a current variation in the coil. Once the resonance is passed, the system returns to equilibrium and the current returns to the value prior to resonance. The spectrum, represented by a curve... 

From the electron beam current variation experiments of Stuckey and Kiser, it is known that two electrons are involved in the overall process of the formation of a doubly-charged negative ion. One of these electrons must be involved in the initial formation of the singly-charged ion by either resonant capture, dissociative resonant... 

Note that rather than presenting the current variations versus a time axis, a current versus potential plot is preferred. Thus in Fig. 23b, the upper trace corresponds to the forward cathodic scan, whereas the lower trace corresponds to the backward anodic scan. 

Hamad David Houle made an appeal to the importance of the consequent variation for any evolutionary thinking. I didn t deny that. What I said was that in a particular case of variation, namely, current individual differences in traits, my points about the relevance of that current variation to the understanding of the trait itself are not a reflection of the importance or non-importance of ancestral variation in evolution. 

Harnad I can put it as a much simpler methodological point, about current, extant creatures. You have an ability, and you have the causal mechanism that underlies it. Then you have current variation in that, on the basis of which you can do this individual difference testing, analyse the correlations, and come up with a g factor, some of it genetic and some non-genetic. The methodological... 

The retardation of the bimolecular reaction on the surface provided a more convenient time domain for observation. 2) Low temperature experiments (-78°C in n-butyronitrile) were easy to perform and allowed a key intermediate to be observed. 3) It was possible to use faster cyclic voltammetry sweep rates (up to 200 V/s) for surface couples because their peak current variation with sweep rate has the same functional dependence (ip v) as for double layer charging currents while for solution couples, ip v 2... 

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