Kernel-Based Calibration for Process Analyzer Reagent Aging
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Solution Overview
Problem
Existing analyzers for determining ion concentrations in process automation technology face challenges due to non-linear relationships between light absorption and substance concentration, which are influenced by external disturbances and reagent aging, leading to inaccurate measurements and the need for frequent recalibration.
Innovation Solution
A method using a kernel-based calibration function that considers reagent aging, incorporating support vector machines or kernel Fisher discriminants to determine measured values, which compensates for reagent age and external influences, allowing for accurate measurements without reagent replacement or analyzer adjustment for up to 12 weeks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear calibration model is used to determine substance concentration from light absorption, then the measurement process is simple, but the measurement precision deteriorates at higher concentrations due to non-linear relationships
Solution Approach 1:
The patent transforms the calibration approach by changing the mathematical model from linear to non-linear (using support vector machines with kernel functions). This allows the system to accurately capture the non-linear relationship between light absorption and substance concentration across the entire measurement range, resolving the contradiction between model simplicity and measurement accuracy at high concentrations.
2Device complexity
If external disturbance variables and reagent aging are not compensated for, then the device operation is simple, but the reliability of measurements deteriorates over time
Solution Approach 1:
The patent incorporates reagent age as a preprocessing parameter in the calibration model before measurement occurs. By including the reagent age variable in the support vector machine calibration function, the system proactively compensates for reagent degradation effects, maintaining measurement reliability throughout the reagent's usable lifetime without requiring frequent recalibration or replacement.
Solution Approach 2:
The system uses the measured light absorption values combined with reagent age information to continuously adapt the calibration model. The support vector machine learns from the relationship between absorption, reagent age, and actual concentration, providing feedback that maintains accuracy even as reagents age and external conditions vary.
3Measurement precision
If frequent recalibration and reagent replacement are performed, then the measurement precision is maintained, but the productivity and operational time are reduced
Solution Approach 1:
The patent performs preliminary calibration that accounts for reagent aging effects throughout the entire reagent lifetime. By incorporating reagent age as a parameter in the support vector machine model during the initial calibration phase, the system prepares for future measurements with aged reagents, eliminating the need for frequent recalibration and extending productive operational time while maintaining precision.
4Ease of manufacture
If the relationship between absorption and concentration is modeled as linear, then the calibration process is simple, but the manufacturing precision of the calibration model deteriorates
Solution Approach 1:
The patent changes the mathematical parameters of the calibration model from linear to non-linear using kernel-based support vector machines. This transformation enables the calibration model to accurately represent the true non-linear relationship between light absorption and substance concentration, significantly improving calibration accuracy while the automated training process keeps the creation process manageable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides accurate ion concentration measurements, maintaining sensitivity across the measuring range and extending analyzer self-sufficiency by accounting for reagent aging, reducing operational costs and time through prolonged reagent usage.
Implementation Method 1
supplying an emitter (17.1) with an exciter signal for producing sent light
Implementation Method 2
the sent light by interaction with, especially by absorption by, the mixed sample is converted into received light as a function of the measured variable
Implementation Method 3
producing a receiver signal by means of the receiver from the converted, received light
Data Source
AI summary
A method and analyzer for determining a measured value of a measured variable of process automation technology in a liquid or gaseous medium by means of an optical sensor includes taking a sample of the medium; mixing the sample with one or more reagents; supplying an emitter of the optical sensor with an exciter signal for producing sent light, wherein the sent light by interaction with the mixed sample is converted into received light as a function of the measured variable; producing a receiver signal by means of a receiver of the optical sensor from the converted, received light; and determining the measured value based on the receiver signal and a calibration function, which includes a term which takes aging of the reagents into consideration.