Amplitude measurements

The maximum permissible vibration, in mils (0.001 in.), during shop test at rated speed shall be equal to the square root of 20,000 divided by the sum of rated speed plus meeh-anieal and eleetrieal runout for the overhung rotor design. Only the aetual total measured runout may be subtraeted from the unfiltered peak-to-peak amplitude measured during testing to attain the shaft vibration. The meehanieal-plus-eleetrieal runout subtraeted from the unfiltered peak-to-peak amplitude shall not exeeed 0.5 mils regardless of total runout. 

There are at least three classifications of amplitude measurements used in vibration analysis broadband, narrow-band, and component. 

The total energy of all vibration components generated by a machine is reflected by broadband, or overall, amplitude measurements. The normal convention for expressing the frequency range of broadband energy is a filtered range between 10 to 10,000 Hz, or 600 to 600,000 cpm. Because most vibration-severity charts are based on this filtered broadband, caution should be exercised to ensure that collected data are consistent with the charts. 

Expertise required to operate One of the objectives for using microprocessor-based predictive maintenance systems is to reduce the expertise required to acquire error-free, useful vibration and process data from a large population of machinery and systems within a plant. The system should not require user input to establish maximum amplitude, measurement bandwidths, filter settings, or allow free-form data input. All of these functions force the user to be a trained analyst and will increase both the cost and time required to routinely acquire data from plant equipment. Many of the microprocessors on the market provide easy, menu-driven measurement routes that lead the user through the process of acquiring accurate data. The ideal system should require a single key input to automatically acquire, analyze, alarm and store all pertinent data from plant equipment. This type of system would enable an unskilled user to quickly and accurately acquire all of the data required for predictive maintenance. 

Frequency Response Analysis the response of an electrode to an imposed alternating voltage or current sign of small amplitude, measured as a function of the frequency of the perturbation. Also called Electrochemical Impedance Spectroscopy. 

Figure 8.1 The duration of NREM sleep and delta activity during NREM sleep following saline (open circles) or 0.5mg/kg MK-801 (filled circles), administered 6h after the start of the dark period. MK-801 initially produced a period of wakefulness approximately 3 h long. In the subsequent light period, NREM sleep duration (A), total integrated amplitude (TIA, a period amplitude measure similar to power) of NREM sleep delta (B), and NREM sleep delta integrated amplitude per minute (IA/min) (C) were all significantly increased above control levels.

For a given grade of SAN, stress amplitude measured in accordance with DIN 53 442 is about 25 MPa for a failure at 10 cycles. 

Konobeev ei al. (K20), 1957 Study of C02 absorption in water films in upward and downward cocurrent flow VKe = 5-200, gas velocities 11.6-39 m./sec. It is suggested that only wavelength and amplitude of interfacial waves affect the rate of mass transfer. Values of wavelength and amplitude measured and compared with previous theories. 

A comparative study of the readout options for the SAW sensor with additional film has shown that for a single SAW sensor the highest signal-to-noise ratio is obtained from the amplitude measurement (Wohltjen and Dessy, 1979). Voltage output related to the phase-shift as discussed above works well for dual delay lines. There are also inherent advantages in measurement of the change of the resonant frequency. The frequency shift due to deposited film of low elastic shear modulus p is... 

Analysis/Synthesis With estimates of excitation and system sine-wave amplitudes and phases at the center of the new time-scaled synthesis frame, the synthesis procedure becomes identical to that of the baseline system of section 3.6. The goal then is to obtain estimates of the amplitudes, Ak (/), and phases, Ok (/), in Equation (9.42) at the center of the synthesis frame of duration Q = pQ where Q is the analysis frame interval as defined in section 3.5. Since in the time-scale modification model, the system and excitation amplitudes are simply time scaled, from Equations (9.40a) and (9.42) the composite amplitude need not be separated and therefore the required amplitude can be obtained from the sine-wave amplitudes measured on each frame m, by spectral peak-picking. 

Fig. 7.52 Electrode reaction of azobenzene at HMDE. The dependence of the peak potential separation of conventional voltammograms (a) and potential-corrected voltammograms (b) on the amplitude, measured at different frequencies ...

It appears that, through a combination of theoretical and experimental efforts, the kinetic methods have developed into one of the most fruitful approaches to the study of physico-chemical properties of micellar systems. One of the main problems that remains to be solved is the kinetics for systems containing rod-shaped micelles where the size distribution is very broad. There is also a problem in the interpretation of the amplitudes measured in the different kinetic experiments. 

The process dynamics is complex. Typical response times vary from a few seconds up to weeks and months. Nonlinear phenomena are common due to large disturbance amplitudes. Measurement and transport time delays cannot be neglected. Sensor location is important due to spatial distributions. As living organisms are part of the system, not only parameters but the structure of the system dynamics can be changed during the operation. 

The FMM images and the corresponding data evaluation of a measurement performed on a respective surface are displayed in Fig. 11. Again, the FMM amplitude measured on epoxy close to the Cu/epoxy borderline is reduced as compared to that measured on bulk epoxy. However, in contradic-... 

Accommodative amplitude measurements after instillation of 2.5% or 10% phenylephrine generally indicate that the effect is far less than the decrease observed with cycloplegic agents such as tropicamide (see Chapter 9). A loss of approximately 2.00 D (7.93 D from 9.95 D) at... 

A number of publications give a good overview of the basics of the optimization of signal processing systems for timing and amplitude measurements... 

Although vidicon-tubes are commercial devices, it still takes a long way to turn them into an excellent X-ray detector. For accurate amplitude measurements, quite some effort has to be invested in the development and tests of the different components. 

Serious complications arise, however, if the spins are subject to strong nuclear electric quadrupolar interactions, which tend to modify the echo amplitudes measured. In such cases, it is still possible to extract dipole-dipole coupling information from spin echo decay spectroscopy, if the 71-pulses are applied entirely selectively to the central l/2>o -l/2> transition [6]. If the resonance frequencies between the coupled nuclei are sufficiently similar to allow for spin-exchange via the flip-flop mechanism, Eq. (5) turns into... 

Practically, DMTA is limited to low frequencies (up to tens of hertz) and, consequently, provides information about relatively slow processes. Dielectric spectroscopy is a related approach in which an alternating electric field is applied to a sample and the complex permittivity is then obtained from phase and amplitude measurements of current and voltage again, it is possible to consider data in the frequency domain, the temperature domain, or even as frequency/temperature contour maps.2 ° 2 See Refs. 230 and 232 for a theoretical account of the underlying physics. The approach can provide information in the frequency range W -io" coupling the applied electric field... 

Sonnefeld, J., Lobbus, M., and Vogelsberger, W.. Determination of electric double layer parameters for spherical silica particles under application of the triple layer model using surface charge density data and results of electrokinetic sonic amplitude measurements, Colloids Surf. A, 195, 215, 2001. 

This representation is suitable if one is interested particularly in both amplitude (measured along the x-axis), and period (measured along the /-axis), both being (quantitative characteristics). Furthermore it may be used for more than one variable, e.g. x and y by plotting multiple graphs for (x, /), (y, /),. The only qualitative information we get is that x is bounded. 

FIG. 4.12 Phase angle and amplitude measurement results for an antibacterial hand soap at 2 Hz using the T2SR rheometer. 

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