One of Cranium's and Synapse's most important capabilities is their ability to select the best estimation technique for a given estimation problem. Both applications perform this selection using techniques' applicability and accuracy rules. These rules determine if an estimation technique is applicable and how accurate it is for a give chemical or mixture. (See documentation on the Model Information Section for additional discussion.)
Developing applicability and accuracy rules starts with evaluating a technique's estimates against experimental values. This is done using the Technique Evaluation Dialog.
The evaluation dialog provides numerous statistics for examining the techniques applicability and accuracy. The interactive graphs can also be very helpful.
|Pressing the dialog's Ignore button will remove the selected records from statistics calculations and graphs.
|Ignored records are displayed in light gray.
|Ignoring outliers can often significantly improve the technique's accuracy.
|Ignored records are not displayed in the evaluation dialog's graphs. The removal of outlining values often reveals additional outlying data points that should be investigated further.
This particular analysis shows that the Cp,l (T): Missenard Method [MKS] does not estimate the liquid heat capacity of water well. Having obtained this result, we should first examine the technique's implementation to ensure no errors are present, and then, assuming correct implementation, consider add an applicability rule to improve the technique's performance.
When evaluating an estimation technique, Cranium and Synapse will use selected manual techniques. We recommend always checking the manual techniques selections and usually clearing all manual technique selections before performing a technique evaluation. (See documentation on the Manual Techniques Dialog for more documentation.)
Given the results of the evaluation performed in the previous example, we will add an applicability rule that excludes the use of the Cp,l (T): Missenard Method [MKS] technique for estimating the liquid heat capacity of water. (Note: this rule may already be present in the knowledge bases you are using.)
Note that the code's result, i.e., the argument to the SetResult function, is the Avg Abs % Error calculated by the Technique Evaluation dialog.
Remember that text values in both Cranium and Synapse are case sensitive. Thus, "ethanol" does not equal "Ethanol". If you wish to make your technique's code more robust, you should account for differences in case. For example, the previous applicable code could be written as:
|Estimating Chemical Properties
|a short video demonstrating how to estimate the physical properties of pure chemical using either Synapse or Cranium.
|Estimating Mixture Properties
|a short video demonstrating how to estimate the physical properties of mixtures using either Synapse or Cranium.
|Getting Started using Cranium
|provides a quick tour of Cranium's capabilities including physical property estimation and a discussion of structure editing.
|Getting Started using Synapse
|provides a quick tour of Synapse's capabilities including examples of chemical product design.