Frequency INDEX

In the internal representation model the time-frequency plane is divided in cells with a resolution of 20 ms along in the time axis (time index m) and of 0.2 Bark along the frequency axis (frequency index /). A first approach was to use the power ratio between the output y and input x, py px in every (At, A f) cell (m, /) as a correction factor for the noise disturbance L (m, l) in that cell (nomenclature is chosen to be consistent with [Beerends and Stemerdink, 1992]). 

Suppression rules. Let X(p,Qk) denote the short-time Fourier transform of x[ri, where p is the time index, and Qk the normalized frequency index (0t lies between 0 and 1 and takes N discrete values for k = 1,N, Wbeing the number of sub-bands). Note that the time index p usually refers to a sampling rate lower than the initial signal sampling rate (for the STFT, the down-sampling factor is equal to hop-size between to consecutive short-time frames) [Crochiere and Rabiner, 1983]. 

In general, it is desired to make the pilot sequence as short as possible, however, very short pilot sequences lead to an inaccurate PDF estimation, and thus to incorrect estimations of Ar and r0nS(H. Fig. 19 shows the estimation performance for Lpii0t = 250,500,1000, and 2000. Fig. 19.(a) depicts 5at which describes the relative estimation error of Ar. For Lpoot = 2000, 8at decreases monotonically with increasing WNR, and is lower than 1% for WNR > —3 dB. Shorter pilot sequences lead to an increased relative estimation error. However, for some WNR, robust estimation is no longer possible at all. Lowering the WNR further introduces so much noise into the PDF estimation that the largest component of the computed DFT spectrum appears at any random frequency index 0 < l < Ldft — 1. 

Furthermore, simulation shows that the random variables Sy icok) and Sy kf ojk ) are un-correlated in the same range of frequencies for the Chi-square distribution, for k k and k, k 6 K.. According to Yaglom [277], uncorrelated Chi-square random variables are independent. Use K to denote the, frequency index set that contains the frequency indices for these approximations to be accurate. Given the observed data V, the spectral set can be computed by using Equation (3.25) ... 

Here the frequency index set K. represents a range over which Equations (3.56) and (3.58) give a satisfactory approximation and this will be further discussed in Section 3.3.3. Using the Bayes theorem, the updated PDF of the model parameter vector 0, given the averaged spectral set [Pg.114]

Another case is investigated with a very short duration of measurement, namely T = 60 s, so it contains roughly 38 fundamental periods of the oscillator. The Bayesian spectral density approach is used for its identification with the frequency index set /C = 1,2,..., 45. Figure 3.13 shows the conditional updated PDFs of and with all other parameters fixed at their optimal values. It is obvious that the conditional PDFs are non-Gaussian so the Gaussian... 

Even though the spectral density approach requires computation of the inverse and determinant of a number of matrices, the size of these matrices is only No y. No. They are significantly smaller than the NgNp x NgNp matrix Eyj j (= E22) required in the time-domain approach. Comparison of the computational efficiency between the two methods depends on the number of the elements in the frequency index set and the number of data points in a fundamental period. The ratio of the computations required by the Bayesian spectral density approach and the Bayesian time-domain approach can be approximated by ... 

Here, the frequency index q = co/fflo and the dimensionless damping coefficient (5 = jS/coo are defined using the resonance frequency for volume oscillations [38],... 

An index is the ratio between two measurements made under different conditions but on the same sample volume. The index can be calculated from measurement results with respect to the results from a gold standard or be based, for instance, upon the same parameter measured at different energies or frequencies. Indexes can also be made by a mathematical operation on the combination of measurement results and other parameters such as, for example, height or weight of the measured person. Actually the phase angle (p = arctan(B/G) is an index. 

Indemnity Case Rate, which is a negative metric providing the rate of all workers compensation cases that involve lost time payments per 100 full time employees per year. It may be indicative of the company s basic prevention and reduction efforts in minimizing more serious lost time case incidence and severity. It relates closely to OSHA s DART or rate of injuries and illnesses resulting in days away from work, restricted work activity, and/or job transfer. According to Italian National Standards UNI 7249 (UNI 2007) further index rates are introduced, like incidence index of occurred accidents, defined as rate of occurred accidents per 1.000 workers, frequency index (rate of occurred accidents per 1.000.000 hours worked), severity index of accidents, which represents 1000 times total number of lost days per hours worked. 

Main ID my 1.2 below actual cate ID. Under main ID, etc. (just an example, or may be escalation issue). FI, frequency index SI, severity index. 

Variations of Fourier series were developed over time to solve certain practical problems. For example, the sine and cosine building-block functions are not concentrated near any particular x value. No position information can be gleaned from just the coefficients at a single frequency index n. On the other hand, an individual sample /(jc ) of a smooth function / indicates roughly how big the function is near x, but confers no frequency information. What was sought was a collection of nice functions w = w k x), with two indices n, k, such that an arbitrary function / = fix) could be written as a superposition ... 

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