Resonance tuning system

A transducer or converted) to convert eleotrioal power into meohanical vibrations. This is a tuned system resonating at the operating frequency. 

In this paper we discuss the resonance tuning hypothesis as an Important mechanism whereby resonances are spread in the F-t-H, and F-+ D2 reaction systems and examine whether the shift from backward to sideways scattering of the HF and DF products Is a resonance signature. All results are obtained using the Muckerman 5 potential surface. 

Xu, B., Duan, F. Chapeau-Blondeau, F. (2004).Comparison of aperiodic stochastic resonance in a bistable system realized by adding noise and by tuning system parameters, Phys. Rev. E, vol. 69, 061110. 

Frequency tuning over at least 10 GHz has been achieved with a magnetic tuning system where the resonator output mirror is mounted on a loudspeaker membrane in a magnetic coil and is displaced linearly with the magnet current. The mechanical construction also allows synchronous tilting of the F.P.I. etalon [7.56]. 

More commonly, the resonant two-photon process in Figure 9.50(c) is employed. This necessitates the use of two lasers, one at a fixed wavenumber Vj and the other at a wavenumber V2 which is tunable. The first photon takes the molecule, which, again, is usually in a supersonic jet, to the zero-point vibrational level of an excited electronic state M. The wavenumber of the second photon is tuned across the M to band system while, in principle, the photoelectrons with zero kinetic energy are detected. In practice, however, this technique cannot easily distinguish between electrons which have zero kinetic energy (zero velocity) and those having almost zero kinetic energy, say about 0.1 meV... 

Because of the tunabiUty, dye lasers have been widely used in both chemical and biological appHcations. The wavelength of the dye laser can be tuned to the resonant wavelength of an atomic or molecular system and can be used to study molecular stmcture as well as the kinetics of a chemical reaction. If tunabiHty is not required, a dye laser is not the preferred instmment, however, because a dye laser requires pumping with another laser and a loss of overall system efficiency results. 

It should be ensured that under no condition of system disturbance w ould the filter circuit become capacitive when it approaches near resonance. To achieve this, the filter circuits may be tuned to a little less than the defined harmonic frequency. Doing so will make the L and hence Xl always higher than Xc, since... 

Once the driver and driven equipment have been chosen and it is deter mined that none of the items will be subject to any lateral vibration problems, the system torsional analysis is performed. If a calculated torsional natural frequency coincides with any possible source of excitation (Table 9-21, the system must be de-tuned in order to assure reliable operation. A good technique to add to the torsional analysis was presented by Doughty [8 j, and provides a means of gauging the relative sensitivity of changes in each stiffness and inertia in the system at the resonance in question. 

Should analysis indicate that a coupling is in a sensitive position, then a small amount of custom design in a relatively standard coupling can accommodate the de-tuning of the critical in question. One note of caution while changes in stiffness or inertia may de-tune a given resonance, their effect on the other criticals must also be determined, since any change in the system will result in a new set of resonant frequencies. 

The ability to create and observe coherent dynamics in heterostructures offers the intriguing possibility to control the dynamics of the charge carriers. Recent experiments have shown that control in such systems is indeed possible. For example, phase-locked laser pulses can be used to coherently amplify or suppress THz radiation in a coupled quantum well [5]. The direction of a photocurrent can be controlled by exciting a structure with a laser field and its second harmonic, and then varying the phase difference between the two fields [8,9]. Phase-locked pulses tuned to excitonic resonances allow population control and coherent destruction of heavy hole wave packets [10]. Complex filters can be designed to enhance specific characteristics of the THz emission [11,12]. These experiments are impressive demonstrations of the ability to control the microscopic and macroscopic dynamics of solid-state systems. 

This system has been developed to acquire NMR spectra with such broad resonance lines that a single RF pulse cannot excite all the spin packets at once. In such a case, it is more convenient to vary the external field and fix the carrier frequency than to change the carrier frequencies with a constant field magnet, because the latter require probe re-tuning at every increment of the carrier frequencies. Moreover, it can alter the efficiency and phase response of the circuit, putting questions on the quantitative analyses of the data. 

An automatic probe tuning and matching (ATM) accessory allows one to automatically tune the NMR probe to the desired nuclei s resonant frequency and match the resistance of the probe circuit to 50 Q [7]. Traditional NMR instruments are designed so that one must perform these adjustments manually prior to data acquisition on a new sample. The advent of the ATM accessory allows the sampling of many different NMR samples without the need for human intervention. The ATM in conjunction with a sample changer enables NMR experiments to be conducted under complete automation. The sample changers are designed so that once the samples are prepared, they are placed into the instrument s sample holders. Data are then acquired under software control of both the mechanical sample delivery system as well as the electronics of the spectrometer. 

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