Retrieval errors

The whole range of error types that could occur at each task step are described in Figure 4.16. The terms action errors and checking errors are self-explanatory. Retrieval errors refer to the retrieval of infonnation either from an external source (e.g., a chart recorder or a procedure) or from memory. Transmission/ communication errors refer to communications among individuals either directly or via written communications. Selection/choice errors refer to making incorrect choices among alternative operations, for example, manual instead of automatic. 

Studies have shown that the retrieval accuracy is particularly sensitive to horizontal temperature gradients. For example, ignoring a temperature gradient of 3 K / 100 km (a typical maximum, e.g. associated with crossing the polar vortex) can lead to composition retrieval errors of tens of %, although these errors are localized and... 

Figure 28.28 Correlation of (a) the particle extinction coefficient at 308 nm, (b) the back-scatter coefficient at 308 nm, (c) the extinction-to-back-scatter DIAL ratio, (d) the effective radius of the particle size distribution, (e) the particle surface-area and (f) the mass concentrations the data were recorded on 4 April 1992. The lidar signal profiles are smoothed with a height window of 600 m for the back-scatter coefficient and 2500 m in all other cases the error bars indicate the overall retrieval error. The optical depth of the stratospheric aerosol layer was 0.25. The dashed line indicates the tropopause. Adapted from Ansmann et al, J. Atmos. Sci., 1997, 54 2630, with permission ofthe American Meteorological Society...

Retrieval errors (e.g. getting information from a screen or manual) information not obtained wrong information obtained information retrieval incomplete. 

Totally 67 errors were identified in all permit to work system tasks including 28 action error, 23 checking error, 8 retrieval error, 5 selection error and 3 information communication error. 

As can be seen in Figure 5-17, some search fields (e.g., POW [= Power]) do not need any input in the search mask this means that all entries with any content of those Helds are retrieved. However, other fields always demand an input. In case the input is omitted (for example for the decadic logarithm of the partition coefficient), a corresponding error message results. Since the PCB are more soluble in the organic phase, the input of that Field is restricted to positive values. 

The filing provisions you have made should enable your records to be readily retrievable however, you need to maintain your files if the stored information is to be of any use. In practice, records will collect at the place they are created and unless promptly removed to secure files may be mislaid, lost, or inadvertently destroyed. Once complete, quality records should not be changed. If they are subsequently found to be inaccurate, new records should be created. Alterations to records should be prohibited as they bring into doubt the validity of any certification or authentication as no one will know whether the alteration was made before or after the records were authenticated. In the event that alterations are unavoidable due to time or economic reasons, errors should be struck through in order that the original wording can still be read, and the new data added and endorsed by the certifying authority. 

Consider the basic probkun of how information is distributed throughout a system, and the manner in which it is retrieved. We. know that in a conventional computer, for example, information is stored in random-access memory (RAM). This means that the memory address of where the information actually exists and the information itself are uncorrelated. In order to retrieve the information, one must know its address exactly, as even the slightest error renders that information effectively unretrievable. In particular, it is in general impossible to retrieve RAM data if armed only with a partial knowledge of its address. In contrast, associative memories (sometimes also called content-addressable memories), much like the form of memory believed to be used by human brains, are such that they can be completely retrieved even when searched for with partial information,... 

In addition to the chemical inferences that can be drawn from the values of AS and AH, considered in Section 7.6, the activation parameters provide a reliable means of storing and retrieving the kinetic data. With them one can easily interpolate a rate constant at any intermediate temperature. And, with some risk, rate constants outside the experimental range can be calculated as well, although the assumption of temperature-independent activation parameters must be kept in mind. For archival purposes, values of AS and AH should be given to more places than might seem warranted so as to avoid roundoff error when the exponential functions are used to reconstruct the rate constants. 

Given a space G, let g (x) be the closest model in G to the real function, fix). As it is shown in Appendbc 1, if /e G and the L°° error measure [Eq. (4)] is used, the real function is also the best function in G, g = f, independently of the statistics of the noise and as long as the noise is symmetrically bounded. In contrast, for the measure [Eq. (3)], the real function is not the best model in G if the noise is not zero-mean. This is a very important observation considering the fact that in many applications (e.g., process control), the data are corrupted by non-zero-mean (load) disturbances, in which cases, the error measure will fail to retrieve the real function even with infinite data. On the other hand, as it is also explained in Appendix 1, if f G (which is the most probable case), closeness of the real and best functions, fix) and g (x), respectively, is guaranteed only in the metric that is used in the definition of lig). That is, if lig) is given by Eq. (3), g ix) can be close to fix) only in the L -sense and similarly for the L definition of lig). As is clear,... 

After a simple Fourier inversion of a set of magnetic structure factors MbU, one can retrieve the magnetisation density. A much better result, e.g. the most probable density map, can be obtained using the Maximum Entropy (MaxEnt) method. It takes into account the lack and the uncertainty of the information not all the Bragg reflections are accessible on the instrument, and all the values contained in the error bars are satisfactory and have to be considered. However, as this method extracts all the information contained in the data, it is important to keep in mind that it may show spurious small details associated to a low accuracy and/or a specific lack of information located in (/-space. 

In 1991 Shi et al. published their seminal observation that high-temperature incubation of formalin-fixed, paraffin-embedded (FFPE) tissue sections in buffers for short periods led to improved immunohistochemical staining.1 However, more than 15 years later, heat-induced antigen retrieval (AR) remains largely an empirical procedure, requiring the optimization of several critical parameters by trial and error.2,3 Further improvements in AR will require an in-depth understanding of the chemistry of formaldehyde fixation and the molecular mechanism(s) underlying the AR method. 

Bottom panel Observed and synthetic Ha profiles for HD 140283 (black 5760K, grey 5560 K). The data was retrieved from the VLT archive (observing date 2000-06-15), reduced using REDUCE and rectified using parabolic fits to the continua in adjacent orders. Notice the variable telluric features which somewhat suppress the blue wing. An effective temperature of 5560 K (best estimate of [3]) is clearly too low, 5760 K (derived from the UVES POP spectrum) too high. At a S/N of 150, observational systematic errors are thus of the order of at least 100 K. 

At first sight many more soft deviations were expected to be found compared to hard deviations, because from accident analysis it is known that in many cases, events triggering the accident are very often human errors, Reason (Reason, 1997). However, considering that soft deviations are often not explicitly reported or known, it makes sense that more hard deviations are present. Retrieving soft deviation information is... 

Should an error be encountered during input, the interpreter will not complete its task. However, it does copy all input to a file from which it may be retrieved, edited and resubmitted in batch mode, making it unnecessary to retype all the equations. 

---