Loop resonator

Fig. 13.1 Photonic sensors that are either based on MNF sensing ((a),(b), (d), (e), (f)) or use MNF for the input and output connection (c), (g) (j). (a) straight MNF sensor with surrounding evanescent field (b) straight MNF sensor coated with bio or chemical layer and surrounding evanescent field (c) generic structure of MNF based optical sensor with surrounding evanescent field (d) straight MNF sensor (e) MNF loop resonator (MLR) sensor (f) MNF coil resonator (MCR) sensor (g) MNF/microsphere sensor (h) MNF/microdisk sensor (i) MNF/micro cylinder sensor (j) MNF/microcapillary sensor (k) a sensor composed of an MNF coupled to a series of microcylinders (optical fibers)...

MNF Loop Resonator, MNF Microsphere Resonator, and MNF /Microdisk Resonator... 

An MLR, which is illustrated in Fig. 13.le, is a miniature version of a fiber loop resonator created from an MNF. An MNF/microsphere resonator and MNF/ microdisk resonator, which are illustrated in Fig. 13.lg, h, consist of an MNF coupled to a microsphere or a microdisk. The excited WGMs are localized in the neighborhood of the microsphere (microdisk) circumference situated in the plane of symmetry of these devices. The transmission power of an MLR, a microsphere, or a microdisk sensor, P(/1), near the resonance wavelength 20 can be found in the form similar to the transmission power of a ring, a disk, and a microsphere resonator66,67 ... 

Sumetsky, M. Dulashko, Y. Fini, J. M. Hale, A. DiGiovanni, D. J., The microfiber loop resonator Theory, experiment, and application, IEEE J. Lightwave Technol. 2006, 24, 242 250... 

I am deeply indebted to the late Professor Jacques Pescia of Universite Paul Sabatier, Toulouse, France, for introducing me to the technique of modulation spectroscopy, with whom I collaborated extensively since 1993, within the framework of Cooperation France-Quebec. (Sadly, he passed away in 2001.) In addition, I am grateful to Professors Sandra Eaton and Gareth Eaton of the University of Denver, USA, for informing me of the crossed-loop resonator technique and pointing out the deficiencies of the pickup coil arrangement. Some sections of this chapter are based closely on unpublished materials that they provided me. 

Rinard GA, Quine RW, Eaton GR, Eaton SS. 2002. 250 MHz crossed-loop resonator for... 

The D loop resonance is downshifted, which indicates a shift away from a gauche, gauche phosphoester configuration toward a gauche, trans. 

It has also been observed that the period of oscillation which a particular loop will exhibit is characteristic of that loop. The loop resonates at that period. Furthermore, any disturbance not periodic, applied to the loop but containing components near the natural period, will excite oscillations of the natural period. A pendulum is a good example of a feedback loop. The controlled variable is the angular position of the mass, and the set point is the vertical position. The mass of the pendulum, acted upon by gravity, is the manipulated variable, which tries to restore the angle to zero. Its natural period in seconds is... 

Because flow loops resonate in the 1- to 10-sec range, they are safe to use in cascade with temperature or composition, but not ordinarily with liquid or gas pressure or other flow loops. Liquid level is only cascaded to flow in applications involving boiling liquids or condensing vapors, where the natural period of the primary loop is long compared to the flow loop. 

Rinard and co-workers described an L-band version of a crossed-loop bi-modal EPR resonator. Like this group s previous S-band version, the crossed-loop resonator consists of two orthogonal LGRs, normally tuned to the same frequency (about 1.9 GHz) with a common sample volume. With appropriate mechanical adjustment it was possible to achieve 60 to 70 dB isolation between the two LGRs this made the resonator ideal for use in pulsed EPR experiments, with one LGR used for transmitting pulses and the other for receiving signals, and a dead-time of less than 60 ns was quoted by the authors. 

Here we have a collection of open-loop transfer functions with simple equations, charts, or tables fiar finding controller gain, reset time, and closed-loop resonant frequency. An example is ... 

For tight pressure contol, we should use these models with caution. Most of the tight column pressure controls we have studied have closed-loop resonant frequencies in the range of 0.5-2 cpm. For the upper value one should make at least a rov h check of condenser and reboiler dynamics. It may be of interest that the only applications of tight pressure control we have found are in heat-recovery schemes where the vapor from one column serves as the heating medium for the reboiler of another column, and perhaps furnishes heat to other loads. If the vapor flow must be throttled to each load, constant up- and downstream pressures help good flow control. 

Other frequently used resonators are dielectric cavities and loop-gap resonators (also called split-ring resonators) [12]. A dielectric cavity contains a diamagnetic material that serves as a dielectric to raise the effective filling factor by concentratmg the B field over the volume of the sample. Hollow cylinders machmed from Ilised quartz or sapphire that host the sample along the cylindrical axis are conunonly used. 

Hyde J S and Froncisz W 1989 Loop gap resonators Advanced ERR in Biology and Biochemistry ed A J Hoff (Amsterdam Elsevier) oh 7, pp 277-305... 

As shown in Figure 27, an in-phase combination of type-V structures leads to another A] symmetry structures (type-VI), which is expected to be stabilized by allyl cation-type resonance. However, calculation shows that the two shuctures are isoenergetic. The electronic wave function preserves its phase when tr ansported through a complete loop around the degeneracy shown in Figure 25, so that no conical intersection (or an even number of conical intersections) should be enclosed in it. This is obviously in contrast with the Jahn-Teller theorem, that predicts splitting into A and states. 

In compounds in which overlapping parallel p orbitals form a closed loop of 4n -f 2 electrons, the molecule is stabilized by resonance and the ring is aromatic. But the evidence given above (and additional evidence discussed below) indicates that when the closed loop contains 4n electrons, the molecule is destabilized by resonance. In summary, 52, 59, and 60 and their simple derivatives are certainly not aromatic and are very likely antiaromatic. 

The analysis of combustion dynamics is then intimately linked to an understanding of perturbed flame dynamics, the subsequent generation of unsteady rates of heat release, and the associated radiation of sound and resulting acoustic feedback. In practical configurations, the resonance loop involves the flow, the combustion process, and the acoustic modes of the system as represented schematically in Figure 5.2.2. 

We have sequenced RpII and studied the structures of RpII and RpIII in solution by 2D-NMR and distance geometry methods. The resonances are almost completely assigned, and secondary and tertiary structures have been determined. Our results indicate that Rp toxins have a four strand anti-parallel )9-sheet and no a-helix. Functionally important residues are found to be located in looped regions of the... 

The deuterium line of the deuterated solvent is used for this purpose, and, as stated earlier, the intensity of this lock signal is also employed to monitor the shimming process. The deuterium lock prevents any change in the static field or radiofrequency by maintaining a constant ratio between the two. This is achieved via a lock feedback loop (Fig. 1.10), which keeps a constant frequency of the deuterium signal. The deuterium line has a dispersion-mode shape i.e., its amplitude is zero at resonance (at its center), but it is positive and negative on either side (Fig. 1.11). If the receiver reference phase is adjusted correcdy, then the signal will be exactly on resonance. If, however, the field drifts in either direction, the detector will... 

Figure 1.10 (a) The dispersion mode line should have zero amplitude at resonance, (b) The deuterium lock keeps a constant ratio between the static magnetic field and the radiofrequency. This is achieved by a lock feedback loop, which keeps the frequency of the deuterium signal of the solvent unchanged throughout the experiment. 

Of course, the distinction between reactive- and bound-state wave functions becomes blurred when one considers very long-lived reactive resonances, of the sort considered in Section IV.B, which contain Feynman paths that loop many times around the CL Such a resonance, which will have a very narrow energy width, will behave almost like a bound-state wave function when mapped onto the double space, since e will be almost equal to Fo - The effect of the GP boundary condition would be therefore simply to shift the energies and permitted nodal structures of the resonances, as in a bound-state function. For short-lived resonances, however, Te and To will differ, since they will describe the different decay dynamics produced by the even and odd n Feynman paths separating them will therefore reveal how this dynamics is changed by the GP. The same is true for resonances which are long lived, but which are trapped in a region of space that does not encircle the Cl, so that the decay dynamics involves just a few Feynman loops around the CL... 

Figure 8 Measure of delocalisation of each defect type predicted by resonance theory. The loops enclose centres which have numbers of classical structures larger than. 74 times the greatest number in the type. The cut-off point for type bi (or type 63) centres is particularly arbitrary since the delocalisation is spread around the equator. The small circles are the point of muonium attachment. The dotted circle is coincident with the equator of Cra-...

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