Shadow Photography Correction for Accurate Particle Volume Flow
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Solution Overview
Problem
Existing shadow photography methods for measuring particle volume flow inaccurately determine particle size due to blurring outside the focal plane, leading to incorrect measurements, and the measurement volume depends on particle size, which affects the precision of particle number, size, and concentration calculations.
Innovation Solution
A method that corrects particle size and measurement volume by calibrating the shadow photography device, determining a focal plane, using a calibration device with predefined diameters, and applying a correction formula based on gradient inclinations to ensure accurate particle diameter determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If particles are measured outside the focal plane, then the measurement volume is increased, but the particle shadows become blurred and appear larger leading to measurement inaccuracies
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements at multiple predefined distances to the focal plane before actual particle measurements. This creates a lookup table of gradient inclination values that are used to correct particle size measurements taken at various distances, thereby compensating for the blurring effect without requiring real-time focal plane adjustments.
Solution Approach 2:
The patent changes the parameter of gradient inclination measurement to compensate for blurring effects. By measuring the gradient inclination of particle shadow edges and using calibration data to correct the apparent particle diameter based on the gradient inclination value, the system maintains measurement accuracy across different distances from the focal plane.
2Ease of operation
If a threshold value is used for binarization, then the image processing is simplified, but the measured particle size becomes dependent on the selected threshold value
Solution Approach 1:
The patent changes from using a fixed threshold value for binarization to using gradient inclination as the measurement parameter. Instead of relying on intensity thresholding that is sensitive to particle size, the method measures the gradient inclination of shadow edges, which provides threshold-independent particle size determination while maintaining the simplicity of digital image processing.
3Quantity of substance
If the measurement volume is increased to capture more particles, then the particle concentration measurement is improved, but the detection of small particles becomes less reliable due to blurring
Solution Approach 1:
The patent performs preliminary calibration at multiple distances to establish the relationship between gradient inclination and apparent particle diameter. This calibration data is then used to correct measurements of particles at various distances, ensuring that small particles are reliably detected and sized even when located outside the focal plane, thereby maintaining detection reliability across an extended measurement volume.
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
Improves the accuracy of particle size and volume flow measurements by compensating for blurring effects and binarization thresholds, ensuring clear assignments and optimal detection efficiency, thereby enhancing the precision of particle number, concentration, and velocity calculations.
Implementation Method 1
measuring a particle volume flow using shadow photography
Data Source
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AI summary
Method for measurement correction in particle volume flow measurements using shadow photography, the method comprising the steps of: calibrating a shadow photography recording device; generating high-resolution shadow photographs of a particle volume flow using the calibrated shadow photography recording device; evaluating the high-resolution shadow photographs; calculating measured values of the particle volume flow; and correcting calculated measured values of the particle volume flow taking into account the value of the gradient slope GS, wherein the value of the gradient slope GS corresponds to the value of a normalized intensity decrease per pixel at a detected particle edge or point edge.