Transformers short-time factors

Table 15.11 Maximum short-time factors obtainable economically corresponding to rated output, accuracy class, accuracy limit factor and rated short-time for wound primary current transformers...

The cure of thermoset resins involves the transformation of a liquid resin, first with an increase in viscosity to a gel state (rubber consistency), and finally to a hard solid. In chemical terms, the liquid is a mixture of molecules that reacts and successively forms a solid network polymer. In practice the resin is catalyzed and mixed before it is injected into the mold thus, the curing process will be initialized at this point. The resin cure must therefore proceed in such a way that the curing reaction is slow or inhibited in a time period that is dictated by the mold fill time plus a safety factor otherwise, the increase in viscosity will reduce the resin flow rate and prevent a successful mold fill. On completion of the mold filling the rate of cure should ideally accelerate and reach a complete cure in a short time period. There are limitations, however, on how fast the curing can proceed set by the resin itself, and by heat transfer rates to and from the composite part. 

Suppression rules. Let X(p,Qk) denote the short-time Fourier transform of x[ri, where p is the time index, and Qk the normalized frequency index (0t lies between 0 and 1 and takes N discrete values for k = 1,N, Wbeing the number of sub-bands). Note that the time index p usually refers to a sampling rate lower than the initial signal sampling rate (for the STFT, the down-sampling factor is equal to hop-size between to consecutive short-time frames) [Crochiere and Rabiner, 1983]. 

The short time limit is Gaussian and determines the envelope of the spectrum, shown in Fig. 6. Since the Fourier transform of a Gaussian in time is a Gaussian in frequency and since a phase factor corresponds to a shift in the frequency, the frequency mQ corresponds to the center of the Franck-Condon band (it is the frequency of the transition turning... 

When an enzyme is added to a reaction mixture, there is first a short lag period before a steady rate of reaction is attained. Once established, the reaction rate remains constant for a finite period of time. This can be as long as several hours, but in other cases it may be as short as only a few minutes. The rate of reaction begins to fall after this period because of factors like reduced substrate concentration or accumulation of end-products. The decrease in reaction rate is not easily analysed mathematically and enzyme studies are thus usually confined to studies of the constant reaction rate. Because the lag phase is extremely short, this reaction rate is computed as the initial reaction rate. In practice, it can be evaluated as the tangent to a curve relating substrate transformed to time. 

The 13C NMR sensitivity can sometimes be a problem, but for the kind of samples studied here the effective concentration of monomer units is several molar which does not place excessive demands on present Fourier transform NMR spectrometers. In addition to the sensitivity of the chemical shift to structure (9), the relaxation of protonated carbons is dominated by dipole-dipole interaction with the attached proton (9). The dependence of the relaxation parameters T, or spin-lattice, and Tor spin-spin, on isotropic motional correlation time for a C-H unit is shown schematically in Figure 1. The T1 can be determined by standard pulse techniques (9), while the linewidth at half-height is often related to the T2. Another parameter which is related to the correlation time is the nuclear Overhauser enhancement factor, q. The value of this factor for 13C coupled to protons, varies from about 2 at short correlation times to 0.1 at long correlation... 

Second, the fluctuation is delayed by a time 5t which is a function of the residence time t, of the element in the reservoir. For an infinite residence time the argument of the tangent tends towards n/2 and the delay 5f towards T/4, while for a short residence time, the delay tends towards zero. As expected, reactive elements respond more rapidly than inert elements. The phase shift and the damping factor relating input to output concentrations represent the angular phase and argument of a complex function known as the transfer function of the reservoir. Such a function, however, is most conveniently introduced via Laplace and Fourier transforms. Applications of these geochemical concepts to the dynamics of volcanic sequences can be found in Albarede (1993). 

The idea of back transformation of a three-dimensional NMR experiment involving heteronuclear 3H/X/Y out-and-back coherence transfer can in principle be carried to the extreme by fixing the mixing time in both indirect domains. Even if one-dimensional experiments of this kind fall short of providing any information on heteronuclear chemical shifts, they may still serve to obtain isotope-filtered 3H NMR spectra. A potential application of this technique is the detection of appropriately labelled metabolites in metabolism studies, and a one dimensional variant of the double INEPT 111/X/Y sequence has in fact been applied to pharmacokinetics studies of doubly 13C, 15N labelled metabolites.46 Even if the pulse scheme relied exclusively on phase-cycling for coherence selection, a suppression of matrix signals by a factor of 104 proved feasible, and it is easily conceivable that the performance can still be improved by the application of pulsed field gradients. 

Transient — Subcycle disturbance in the AC waveform evidenced by a sharp, brief discontinuity of the waveform. This may be of either polarity and may be additive or subtractive from the nominal waveform. Transients occur when there is a sudden change in the voltage or the current in a power system. Transients are short-duration events, the characteristics of which are predominantly determined by the resistance, inductance, and capacitance of the power system network at the point of interest. The primary characteristics that define a transient are the peak amplitude, the rise time, the fall time, and the frequency of oscillation. Figure 1.12 shows a transient voltage waveform at the output of a power transformer as the result of switching-in of a motor containing power factor correction capacitors. 

Abstract. The Coulomb interaction which occurs in the final state between two particles with opposite charges allows for creation of the bound state of these particles. In the case when particles are generated with large momentum in lab frame, the Lorentz factors of the bound state will also be much larger than one. The relativistic velocity of the atoms provides the oppotrunity to observe bound states of (-n+fx ), (7r+7r ) and (7x+K ) with a lifetime as short as 10-16 s, and to measure their parameters. The ultrarelativistic positronium atoms (.4oe) allow us to observe the effect of superpenetration in matter, to study the effects caused by the formation time of A e. from virtual e+e pairs and to investigate the process of transformation of two virtual particles into the bound state. 

In contrast to Xenopus laevis, the maternal histone pool in the mouse one-cell embryo (based on synthetic rates for histones) is probably sufficient for only one to two rounds of DNA replication (Wassarman and Mrozak, 1981). Consistent with such a small histone pool is the observation that poly spermic eggs have the capacity to transform up to three to four sperm nuclei into metaphase chromosomes (Clarke and Masui, 1986) a similar capacity was also determined from experiments that manipulated the cytoplasmic volume by either bisection or cell fusion (Clarke and Masui, 1987). This small pool of maternal histones may hence be insufficient to prevent effectively the assembly of stable basal transcription complexes. Thus, titration of the maternal histone pool by an increase in the mass of DNA due to blasto-mere proliferation may not be a critical factor in regulating the onset of transcription in the mouse embryo and other mammalian eggs this is because the maternal transcription factors may be able to outcompete successfully maternal histones for the newly replicated chromatin. This could, at least in part, account for the early onset of transcription in mammalian embryos ranging from rodents to humans (Telford et al., 1990). Moreover, the lack of arapid S phase in the mouse embryo and other mammalian embryos would permit sufficient time for productively assembled transcription complexes to generate full-length transcripts. In contrast to mammalian embryos, S phase is very short prior to the midblastula transition in Xenopus laevis (Newport and Kirschner, 1982) and hence these rapid rounds of DNA replication could prematurely terminate the transcription of genes for which transcription had initiated. 

---