Error logs, computer system

All quality systems need to demonstrate that the equipment used is properly maintained and in some instanees ealibrated. Computers are no exception to this. Therefore, records of the maintenance of the CDS need to be set up and updated in line with the work carried out on it. The main emphasis of the maintenance records is toward the physical components of a system hardware, networking, and peripherals. The software maintenance is covered imder the error logging system described above. 

Windows NT, like other network operating systems, employs comprehensive error and informational logging routines. Every program and process theoretically could have its own logging utility, but Microsoft has come up with a rather slick utility, Event Viewer, which, through log files, tracks all events on a particular Windows NT computer. Normally, though, you must be an administrator or a member of the Administrators group to have access to Event Viewer. 

To start Event Viewer, log in as an administrator (or equivalent) and go to Start > Programs > Administrative Tools > Event Viewer. Erom here you can view the System, Application, and Security log files. The System log file displays alerts that pertain to the general operation of Windows. The Application log file logs server application errors. The Security log file logs security events such as login successes and failures. These log files can give a general indication of a Windows computer s health. 

Estimation of model error bars and sensitivity analyses are based rai the same principle. AU rate coefficients (or other model parameters) of a system are randomly varied within a certain range. The chemical evolution is then computed for each set of rate coefficients. For a network containing 4,000 reactions, the model is typically run 2,000 times with different sets of rate coefficients. The distribution of the rate coefficients can be either log-normal or log-uniform (see Fig. 4.5). The first choice implies that the mean value ko is a preferred value. This is usually the case for rate coefficients, which are measured with an uncertainty defined by statistical errors. The factor Fq, which defines the range of variation, can be a fixed factor for aU reactiOTis for a sensitivity analysis or specific to each reaction for an uncertainty propagation study. Use of the same Fq for all reactions, in the case of a sensitivity analysis, assures the modeller that an underestimated uncertainty factor will not bias the analysis. The results of thousands of runs are used differently to identify important reactions and to estimate model error bars. 

A typical printout of the instrumentation performance analysis algorithm is shown in Fig. 12. The error computation is not accurate for reactor period signals, which are differential in nature and have large fluctuations around the mean value. The mean-value of the period signals is however useful for reactor operator. There have been many instances where the computer has detected a noisy instrumentation chaimel or detector, and the problem was corrected by maintenance. It was observed that by replacing the detector signal cables by double shielded cable in the startup channels, the scatter in neutron counts signal reduced by a factor of two. The time constant of the log countrate meter was also adjusted with the help of the system to obtain minimum error. 

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