Negative phase

The RF field is applied in such a way that one pair of opposed rods has the positive phase applied and the other pair has the negative phase apphed. 

An RF field is applied to the rings. The positive phase is applied to every other ring and the negative phase to the remaining intervening rings. Such an ion guide is called an ion tunnel. 

Protection against voltage unbalance or negative phase sequence 12/291... 

Voltage unbalance (negative phase sequenceJ This causes negative sequence components and results in excessive heating of the motor windings. An unbalanced voltage may occur due to unevenly distributed single-phase loads. 

Impedanceofa motor during a normal running condition to a negative phase sequence voltage will be almost the... 

Figure 12.23(a) Schematic (or a negative phase sequence (NPS) relay... 

Negative Phase Sequence Relay, M/s English Electric Co. of India Ltd, Catalogue Ref. PR 0I 306 A. 

Zj = Negative phase sequence impedance Zq = Zero phase sequence impedance... 

Generators that are solidly grounded have a different grounding practice from others due to their zero phase sequence reactance, which is much less than its positive or negative phase sequence reactances (Section 13.4. ((. i))... 

In the surrounding atmosphere, a blast wave is experienced as a transient change in gas-dynamic-state parameters pressure, density, and particle velocity. Generally, these parameters increase rapidly, then decrease less rapidly to sub-ambient values (i.e., develop a negative phase). Subsequently, parameters slowly return to atmospheric values (Figure 3.7). The shape of a blast wave is highly dependent on the nature of the explosion process. 

The most important blast-wave parameters are peak overpressure and positive impulse i, as shown in Figure 6.11. The deep negative phase and second shock are clearly visible in this figure. 

Negative phase That portion of a blast wave whose pressure is below ambient. 

The gauge records eimbient pressure Pq. At arrival time ta, the pressure rises quite abruptly (discontinuously, in an ideal wave) to a peak value Pj + Pq. The pressure then decays to ambient in total time tg + T+, drops to a partial vacuum of amplitude Pj, and eventually returns to Po in total time tg + T+ + T. The quantity P is usually termed the peak side-on overpressure, or merely the peak overpressure. The portion of the time history above initial ambient pressure is called the positive phase, of duration T+. That portion below Po, of amplitude Ps and duration T, is called the negative phase. 

As mentioned already, the INEPT spectra are typified by the antiphase character of the individual multiplets. The INEPT C-NMR spectrum of 1,2-dibromobutane is shown, along with the normal off-resonance C-NMR spectrum, in Fig. 2.12. Doublets show one peak with positive phase and the other with negative phase. Triplets show the outer two peaks with positive and negative amplitudes and the central peak with a weak positive amplitude. Quartets have the first two peaks with positive amplitudes and the remaining two peaks with negative amplitudes. 

Blast wave (Overpressure and negative phase pressure relative to atmospheric condition) Diffraction loading—forces on a structure resulting from the direct and reflected overpressure... 

The theory behind both of these experiments, and in particular the DEPT experiment, is rather complicated, so that we refer you to NMR textbooks for details. The important feature of both is that the carbon signals appear to have been simply broad-band decoupled, but that according to the multiplicity they appear either in positive (normal) phase or in negative phase, according to their multiplicity. 

APT, you will perhaps remember, stands for Attached Proton Test, meaning that this spectrum tells you the multiphcity of the signals (Me, CH2, CH or quaternary C). These two spectra tell you how many magnetically non-equivalent types of carbon are present in the molecule, but (for the reasons we discussed earlier) we do not use integration to try to find out relative numbers. We shall present APT spectra as follows CH, CH3 in negative phase (down), CH2 and quaternary C in positive phase (up). 

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