Bandwidth methods

Common Methods for Damping Measurement Logarithmic Decrement and Bandwidth Method... 

After the transformation of the response signal into the frequency domain, the damping ratio of a linear, viscously and lightly damped system can be determined using the bandwidth method given by... 

FRAs provide a very convenient, high-precision, wide-bandwidth method of measuring impedances in electrochemical systems. Commercial instruments are available which provide up to 4 digits of precision in the real and imaginary components, in frequency ranges covering 10 to lO Hz. These are direct-measuring devices and therefore are not susceptible to limitations on imposed potentiostat control. 

Damping can be determined using the half-power bandwidth method or from the logarithmic decrement by placing the sample in free vibration (ASTM 2007). This technique has been modified to allow cyclic torsional shear testing to strain levels above those typically achieved during a... 

In many instanees, it is important tiiat some fonn of ehemieal seleetivity be applied in magnetie resonanee imaging so as to distinguish nuelei m one or more speeifie moleeular enviromnent(s). There are many ways of doing this and we diseuss here just three. The first option is to ensure that one of the exeitation RF pulses is a narrow bandwidth, frequeney seleetive pulse applied in the absenee of any gradient [22]. Sueh a pulse ean be made speeifie to one partieular value of the ehemieal shift and thereby aflfeets only nuelei with that ehemieal shift. In praetiee this ean be a reasonable method for the speeifie seleetion of fat or oil or water in a mixed hydoearbon/water system. 

The compensation schemes shown in this book are the most common methods. Several of these will work in each applications, but only one for each is considered the optimum method insofar as the dc gain and closed-loop bandwidth aspects are concerned. Tables B-1 and B-2 will help match a possible compensation method with your application. 

The first step in determining the component values for this compensation method is to determine the inherent dc gain of the power stages. The calculation should be performed with the maximum value of the input voltage, since this is where the system will have its widest exhibited bandwidth. This is done using Equation B.12. 

Self-diffusion coefficients were measured with the NMR spin-echo method and mutual diffusion coefficients by digital image holography. As can be seen from Figure 4.4-3, the diffusion coefficients show the whole bandwidth of diffusion coeffi-... 

The second method uses the slip frequency to monitor for loose rotor bars. The passing frequency created by this failure mode energizes modulations associated with slip. This method is preferred since these frequency components are within the normal bandwidth used for vibration analysis. 

Back e.m.f. 505 Back titration 311, 324 Balance analytical care and use, 75 constant load, 73 electronic, 73 free swinging, 73 maximum load of, 74 single pan, 73 Balance top pan, 75 tare facility, 74 Balancing method 652, 656 Bandwidth 663... 

The preferable excitation source is an Nd-YAG laser because of its bandwidth (which is only about 0.3 ps), its easier mode locking, and its wavelength range. The use of an ultrafast laser creates the need for time resolution in a similarly short regime. The fastest photodiodes and oscilloscopes cannot resolve times <50 ps, and so other methods have been developed. One of them is the streak camera but it is not all that fast (0.5-5 ps resolution), and it is none too sensitive to small signals. 

In the DC-biased structures considered here, the dynamics are dominated by electronic states in the conduction band [1]. A simplified version of the theory assumes that the excitation occurs only at zone center. This reduces the problem to an n-level system (where n is approximately equal to the number of wells in the structure), which can be solved using conventional first-order perturbation theory and wave-packet methods. A more advanced version of the theory includes all of the hole states and electron states subsumed by the bandwidth of the excitation laser, as well as the perpendicular k states. In this case, a density-matrix picture must be used, which requires a solution of the time-dependent Liouville equation. Substituting the Hamiltonian into the Liouville equation leads to a modified version of the optical Bloch equations [13,15]. These equations can be solved readily, if the k states are not coupled (i.e., in the absence of Coulomb interactions). 

Fortunately, an alternative method of excitation exists, instead of the sequential excitation of nuclei by the slow variation of the magnetic field. This involves the application of a short but intense radiofrequency pulse extending over the entire bandwidth of frequencies in which the nuclei to be observed resonate, so that all the nuclei falling within the region are excited simultaneously. As a result the total scan time is made independent... 

Shafqat et al. ° previously validated the National Institutes of Health Stroke Scale (NIHSS) assessment as a reliable method of evaluating patients with stroke symptoms at a bandwidth of 384 kbit/s comparing a bedside neurologist to a telemedicine-enabled neurologist teamed with a bedside nurse in patients with ischemic stroke and NIHSS scores ranging from 1 to 24. There was an excellent correlation between bedside and remote scores (inter-rater correlation coefficient... 

In the time-domain detection of the vibrational coherence, the high-wavenumber limit of the spectral range is determined by the time width of the pump and probe pulses. Actually, the highest-wavenumber band identified in the time-domain fourth-order coherent Raman spectrum is the phonon band of Ti02 at 826 cm. Direct observation of a frequency-domain spectrum is free from the high-wavenum-ber limit. On the other hand, the narrow-bandwidth, picosecond light pulse will be less intense than the femtosecond pulse that is used in the time-domain method and may cause a problem in detecting weak fourth-order responses. 

S.3.4.3. Photodissociation It is also possible to use light as the activation method. Laser sources are especially useful because of their high intensity and narrow wavelength bandwidth. Photodissociation can be used to determine bond dissociation energies in ions directly, similar to what is done with threshold CID, or, alternatively, can be used in conjunction with direct ionization. 

Capillary electrophoresis offers several useful methods for (i) fast, highly efficient separations of ionic species (ii) fast separations of macromolecules (biopolymers) and (iii) development of small volume separations-based sensors. The very low-solvent flow (l-10nL min-1) CE technique, which is capable of providing exceptional separation efficiencies, places great demands on injection, detection and the other processes involved. The total volume of the capillaries typically used in CE is a few microlitres. CE instrumentation must deliver nL volumes reproducibly every time. The peak width of an analyte obtained from an electropherogram depends not only on the bandwidth of the analyte in the capillary but also on the migration rate of the analyte. 

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