Modulation wave

Overall, the RDE provides an efficient and reproducible mass transport and hence the analytical measurement can be made with high sensitivity and precision. Such well-defined behavior greatly simplifies the interpretation of the measurement. The convective nature of the electrode results also in very short response tunes. The detection limits can be lowered via periodic changes in the rotation speed and isolation of small mass transport-dependent currents from simultaneously flowing surface-controlled background currents. Sinusoidal or square-wave modulations of the rotation speed are particularly attractive for this task. The rotation-speed dependence of the limiting current (equation 4-5) can also be used for calculating the diffusion coefficient or the surface area. Further details on the RDE can be found in Adam s book (17). 

The difficult part of the problem is to identify and describe the mechanism by which the acoustic wave modulates the combustion rate. There are many possible mechanisms by which an acoustic wave can influence combustion, and the dominant mechanism varies with the design of the combustion device. Possible coupling mechanisms include... 

In connection with the square-wave technique, mention can be made of high-frequency polarography, also called radiofrequency polarography and developed by Barker53, in which a sinusoidal radio-frequency cu, (100kHz to 6.4 MHz) square-wave modulated at co2 (225 Hz) is superimposed on to the dc potential ramp as the wave form includes (apart from additional higher... 

A small square wave modulation of the current is applied in order to disturbe the non-equilibrium steady state of the discharge. The exponential decay of the concentrations leads to characteristic relaxation times, which allow the calculation of rate constants used in the modeling of the deposition mechanism. 

Figure 3.8 Current-potential linear sweep voltammogram and the differential reflectivity change in the hydrogen adsorption region at fixed wavelengths (a) 2.34 pm and (b) 1.93 pm. The sweep rate was 15mVs with a square wave modulation of lOmV at 8.5 Hz. From Bewick et al.

The spectra recorded for the hole injection process by the thianthrene radical cation into the Au(lll) electrode are shown in Fig 4, for three different excitation energies. Once again, square wave modulation was employed with a fixed positive value of +1.0V where the cation radical is produced /4/ to negative values... 

Fig. 9.16 A sine wave modulation of the etching current produces an array of macropores with a corresponding modulation of diameter.

Perhaps the first detailed discussion of such a technique in fluorescent thermometry (shown in Figure 11.10) was given by Zhang et al. in their work(36) based on both mathematical analysis and experimental simulation. Examples of the electronic design of the corresponding system and the application of the technique in a ruby fluorescence-based fiber-optic sensor system are also listed. This shows that there is no difference in the measurement sensitivity between a system using square-wave modulation and one using sinusoidal modulation. However, the former performs a little better in terms of the measurement resolution. 

V at 100 MC/sec compared with 10 kV in Kerr cells) and they transmit over a wide spectral range (2500-12000 A). When designed as travelling wave modulators, they can be used even up to micro-wave modulation frequencies... 

The fundamental performance parameter of any detector is its noise equivalent power (NEP). This is simply the input irradiance power necessary to achieve a detector output just equal to the noise. This NEP is dependent on a number of detector and signal variables such as modulation frequency and wavelength (the input signal is defined as sine wave modulated monochromatic light), and detector area, bandwidth and temperature. 

Figure 3, Triplet EPR spectra of TCP 10 M) in CH Cl-CH OH recorded at about 10 K. Microwave power 0,5 mW field modulation 20 G (100 kHz) excitation with square wave modulated (83 Hz) light of an argon laser (514.5 am 0.5 W). (a) No addition (b) with NaCl (- 5 x 10 M) and (c) with KCl ( 5 X 10 N). Absorption and emission peaks have been labeled A and E. respectively.

Figure 4, Triplet EPR spectra of ZnTCP ( -10 ) in Cn Cl-CII OH recorded at 10 K before (solid line) and after (dotted line) addition of KCl ( S x 10 ). Microwave power 0.5 mW, field modulation 20 gauss (100 kHz), excitation with square wave modulated (13 Hz) light from an Xe high pressure arc (1000 W) passed through a CuSO heat filter.

Fig. 21. Sine-wave modulation observed above Tjj = 18.5 K in NpAs2- (Rossat-Mignod et al. )...

We observed the silver doublet again, this time with a 27-Hz square-wave modulation applied to the retarding potential of the energy analyzer. The spectrometer thus was made to alternate rapidly between two different scan... 

Fig. 3.2 The fast beam approach of Bayfield and Koch (ref. 13). H+ ions of roughly 10 keV energy pass through a charge exchange cell forming a fast beam of H Rydberg atoms. Down-stream from the charge exchange cell the ions are deflected from the beam and a band of n states is selected by a square wave modulated ionization field.

Most of the high precision spectroscopy of He Rydberg states has been done by microwave resonance, which is probably the best way of obtaining the zero field energies. Wing et a/.8-12 used a 30-1000pA/cm2 electron beam to bombard He gas at 10-5-10-2 Torr. As electron bombardment favors the production of low states, it is possible to detect A transitions driven by microwaves. The microwave power was square wave modulated at 40 Hz, and the optical emission from a specific Rydberg state was monitored. When microwave transitions occurred to or... 

The simple analysis presented above confirms that new formulations are required to produce stable, reliable products for field use. Practical system requirements, as defined by Mil Spec conformity and the use of standard fabrication and assembly processes, definitely require that a electro-optic polymer system with better thermal properties than thermoplastic acrylates be developed. That this is true for optical interconnection boards and modules is not surprising because of their complexity. It is perhaps remarkable that it remains true for even simple devices, such as a packaged, pigtailed traveling-wave modulator. The ultimate success of electro-optic polymers will be their use in cost-effective products that are used by systems designers. 

The functions in eq. (26) are called Bloch functions and are plane waves modulated by the function nk(r), which has the periodicity of the lattice,... 

A time-dependent quantity X t) responding to the sine wave modulation of some low level perturbation dKcos a>t and frequency a>/2n, is generally written in linear conditions as ... 

In a particular case of a sine wave modulation of low amplitude, a similar relation can be written with the complex quantities. Differentiating Eq. (1-1) for each frequency and considering the fact that /, E or Q are independent variables two by two, one obtains ... 

S. Brukenstein et al. proposed in 1973 [5] this technique as an alternative to the sine-wave modulation technique. Their approach was based on the Benton s analysis of fluid flow near an impulsively started disk from rest [61]. They assumed that the... 

These locally-scaled plane-waves are precisely the equidensity orbitals of Har-riman [25]. When the generating orbitals of Eq. (20) are substituted into Eqs. (9) and (10) (for the latter we assume spherical symmetry, viz., 1 = 0 for all i) we obtain the following constant term for the local-scaling plane-wave modulating function... 

With today s continuous-wave modulation techniques in telecommunications the necessary nonlinearities are very difficult if not impossible to achieve. However, for other transmission schemes (e.g. solitons) and new potential concepts the development of organic materials fulfilling the requirements imposed by applications may is possible. 

Square-wave voltammetry is a large-amplitude differential technique in which a waveform composed of a symmetric square wave, superimposed on a base staircase potential, is applied to the working electrode (8) (Fig. 3.9). The current is sampled twice during each square-wave cycle, once at the end of the forward pulse (at h) and once at the end of the reverse pulse (at t2). Since the square-wave modulation amplitude is very large, the reverse pulses cause the reverse reaction of the product (of the forward pulse). The difference between the two measurements is plotted versus the base staircase potential. 

The first successful ROA measurements were achieved with the use of an electro-optic modulator (EOM) operating in a square-wave modulation cycle. 

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