Data analysis time constants

Loss of offsite power at nuclear power plants is addressed in EPRI NP-2301, 1982 giving data on the frequency of offsite power loss and subsequent recoveiy at nuclear power plants. Data analysis includes point estimate frequency with confidence limits, assuming a constant rate of occurrence. Recovery time is analyzed with a lognormal distribution for the time to recover. 

In this section, the analysis of the data reconciliation problem is restricted to quasi-steady-state process operations. That is, those processes where the dominant time constant of the dynamic response of the system is much smaller than the period with which disturbances enter the system. Under this assumption the system displays quasi-steady-state behavior. The disturbances that cause the change in the operating conditions may be due to a slow variation in the heat transfer coefficients, catalytic... 

Involves converting concentrations to the ratio of an Individual specie to the total concentration of all dissolved species. The data analysis Is then performed on these normalized or relative concentrations. To the degree that an assumption of constant scavenging efficiency holds (each element Is removed from the atmosphere with equal efficiency) relative concentrations might be expected to better reflect the Influence of a pollution source, which, over time might experience differing amounts of dilution by air and water. This technique may produce spurious correlations due to closure (the constant sum) depending on the data structure before normalization ( ). 

Experimental Analysis. The most reliable process measurement is the oscillator frequency from the PAAR densitometer. Along with the frequency, the temperature is also measured ( 0.05 C). These two states are used to interpolate the solute concentration. CSD weight percent information and obscuration measurements were obtained from the Malvern Particle Sizer. Approximately 500 concentration data points and 200 CSD and obscuration measurements were recorded during a run of about 80 -100 minutes. Therefore, the dynamics of the system were well monitored, i.e., the time constant of the crystallizer is much larger than the sampling time. We have performed 25 experimental runs. This section summarizes the analysis of a single, typical experiment. 

Since mass transfer between phases occurs for all time t, the mass and volumes of each phase are non-constant in the interval between initial and final reaction times [tospectroscopic results and data analysis, particularly when calculating moles present. 

As shown in the preceding two sections, the constant time version of REDOR, CT-REDOR, may be applied as an expedient alternative to the existing REDOR versions in the presence of strong heteronuclear dipolar couplings. In these cases, only few data points are available for the data analysis, which especially in the case of multiple-spin systems renders an evaluation of the second moments impossible. The efficiency of the dipolar recoupling may be intentionally reduced either via a dislocation of the dephasing Ti-pulses from the centre of the rotor period or via an application of non-Ti-dephasing pulses. A variation of the pulse position fpp... 

The correlation function data are then transformed by a digital analog converter and displayed on an oscilloscope where the evolution of Ci(r) may be conveniently watched. Alternatively, the digital output may be punched on paper tape for subsequent analysis. A typical solution will allow Ci(t) to develop in 5-15 sec with sufficient signal to noise ratio to obtain the time constant with an accuracy of 1% or better. 

To reach steady state, the residence time of the fluid in a constant stretch rate needs to be sufficiently long. For some polymer melts, this has been attained however, for polymer solutions this has proved to be a real challenge. It was not until the results of a world wide round robin test using the same polymer solution, code named Ml, became available that the difficulties in attaining steady state in most extensional rheometers became clearer. The fluid Ml consisted of a 0.244% polyisobutylene in a mixed solvent consisting of 7% kerosene in polybutene. The viscosity varied over a couple of decades on a logarithmic scale depending on the instrument used. The data analysis showed the cause to be different residence times in the extensional flow field... 

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