Noise characterization

Improving the noise characterization. In many real life applications, the hypothesis that the noise is stationary is unrealistic and it is necessary to track the time-variations... 

We give two examples of fractal time series. The first is fractal Gaussian intermittent noise characterized by a long-time correlated waiting-time sequence, and the second is a Levy-walk intermittent noise. These examples were developed in an environmental context to explain the observed distribution of earthquakes in California [66]. 

The other form of noise found in semiconductors is 1// power law noise, characterized by a spectrum in which the noise power depends approximately inversely upon frequency. The general expression for the noise current is... 

In TFRs, the current noise (1//behavior) dominates over the thermal noise. Current noise is caused by the conduction mechanism between the resistive particles in the microstructure. For noise characterization, the Quan-Tech noise measuring method is used ... 

T)) is given by a zero mean Frisson white noise characterized by TX- W-) the stochastic master equation is meaningful for X-w. 

Minimum exposure times must be observed in order to reach the requisite S/N ratio. As per EN 1435 and EN 584-1, for the different ranges of utilization (energy, wall thickness), definite film elasses are prescribed. They are characterized by the minimum gradient-to-noise ratios. Based on this, one can calculate the minimum values for the S/N ratio based on the IP systems. The exposure time and the device parameter sensitivity and dynamics (latitude) must be adjusted accordingly, with an availability of an at least 12 bit system for the digitalization. 

As any conventional probe, acoustic beam pattern of ultrasound array probes can be characterized either in water tank with reflector tip, hydrophone receiver, or using steel blocks with side-drilled holes or spherical holes, etc. Nevertheless, in case of longitudinal waves probes, we prefer acoustic beam evaluation in water tank because of the great versatility of equipment. Also, the use of an hydrophone receiver, when it is possible, yields a great sensitivity and a large signal to noise ratio. 

Based upon a piezoelectric 1-3-composite material, air-bome ultrasonic probes for frequencies up to 2 MHz were developped. These probes are characterized by a bandwidth larger than 50 % as well as a signal-to-noise ratio higher than 100 dB. Applications are the thickness measurement of thin powder layers, the inspection of sandwich structures, the detection of surface near cracks in metals or ceramics by generation/reception of Rayleigh waves and the inspection of plates by Lamb waves. 

Equation (A3.3.57) must be supplied with appropriate initial conditions describing the system prior to the onset of phase separation. The initial post-quench state is characterized by the order parameter fluctuations characteristic of the pre-quench initial temperature T.. The role of these fluctuations has been described in detail m [23]. Flowever, again using the renomialization group arguments, any initial short-range correlations should be irrelevant, and one can take the initial conditions to represent a completely disordered state at J = xj. For example, one can choose the white noise fomi (i /(,t,0)v (,t, 0)) = q8(.t -. ), where ( ) represents an... 

The noise is expressed as noise density in units of V/(Hz), or integrated over a frequency range and given as volts rms. Typically, photoconductors are characterized by a g-r noise plateau from 10 to 10 Hz. Photovoltaic detectors exhibit similar behavior, but the 1/f knee may be less than 100 Hz and the high frequency noise roU off is deterrnined by the p—n junction impedance—capacitance product or the amplifier (AMP) circuit when operated in a transimpedance mode. Bolometers exhibit an additional noise, associated with thermal conductance. 

The performance of a centrifugal compressor (discharge to suction-pressure ratio vs. the flow rate) for different speeds is shown in Fig. 11-87. Lines of constant efficiencies show the maximum efficiency. Unstable operation sequence, called surging, occurs when compressors fails to operate in the range left of the surge envelope. It is characterized by noise and wide fluctuations of load on the compressor and the motor. The period of the cycle is usually 2 to 5 s, depending upon the size of the installation. 

Nitrophenyl groups covalently bonded to classy carbon and graphite surfaces have been detected and characterized by unenhanced Raman spectroscopy in combination with voltammetry and XPS [4.292]. Difference spectra from glassy carbon with and without nitrophenyl modification contained several Raman bands from the nitrophenyl group with a comparatively large signal-to-noise ratio (Fig. 4.58). Electrochemical modification of the adsorbed monolayer was observed spectrally, because this led to clear changes in the Raman spectrum. 

Is PPE selected and used to protect employees from the hazards and potential hazards they are likely to encounter as identified during the site characterization and analysis (including physical hazards such as heat stress, ionizing radiation, and noise) ... 

As regards the noise spectrum, the different situations can be analyzed ap proximately with NC (noise criterion) and NR (noise rating) curves (Fig. 9.6.3). NC and NR curves define the octave band limits of an acceptable back ground noise each of them is characterized by a number representing the sound pressure level at 1000 Hz. 

Regimes I-III are each characterized by peaks immersed in broad-band noise. In regime IV the peaks are replaced by a Lorentzian band noise around [kaneko89]. 

Few, if any, minor signals are in evidence for which the signal-to-noise ratio is good and which can be assigned to known chemical entities that are available in quantities sufficiently large to allow for a complete physicochemical characterization. 

All f.a.b. spectra are characterized by (a) abundant, pseudomolecular ions for both the sample and the matrix, and (b) a relatively high level of chemical noise, resulting in a signal at every mass number up to the... 

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