Open-Path Air Contaminant Detection Moving Average Filtering
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Solution Overview
Problem
Current methods for detecting air contaminants using open-path spectroscopic analyzers face challenges in accurately determining concentration levels due to noise and error introduction from atmospheric temperature scintillation and require frequent updates of background measurements, which can be inefficient.
Innovation Solution
The method involves obtaining single beam measurements frequently, calculating moving average sample and background values, and determining a moving average differential Double Beam value to evaluate the quantity of air contaminants through transmission, absorption, or extinction, using a system with an active or passive optical remote sensing system that includes an EM radiation source, wavelength separator, and detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent background measurements are performed to update baseline data, then measurement precision is improved, but productivity deteriorates due to time consumption
Solution Approach 1:
The system performs preliminary background measurements during periods when no plume is present to establish baseline atmospheric conditions. This preliminary action allows the system to pre-characterize atmospheric absorption and scattering properties, so that when a plume appears, the pre-established baseline can be used for rapid concentration calculations without requiring continuous background updates.
Solution Approach 2:
The system implements periodic background measurements at predetermined time intervals rather than continuously updating the baseline. The processor is configured to acquire background spectra at specific intervals and use these periodic updates to maintain accurate concentration measurements, balancing the need for baseline accuracy with efficient plume detection timing.
2Productivity
If single beam measurements are used for rapid detection, then productivity is improved, but measurement precision deteriorates due to noise from atmospheric temperature scintillation
Solution Approach 1:
The system extracts and removes the atmospheric baseline signal from the total measured signal. By separating the atmospheric absorption and scattering components (obtained from background measurements) from the plume signal, the system can subtract the atmospheric contribution, leaving only the plume-related absorption features. This extraction process eliminates atmospheric temperature scintillation noise while preserving the rapid detection capability of single-beam measurements.
Solution Approach 2:
The background spectrum serves as an intermediary that mediates between the raw single-beam measurement and the final concentration calculation. The processor uses the background spectrum to calculate the plume spectrum by subtraction, and this intermediary step allows the system to maintain the speed of single-beam measurements while achieving the precision of differential measurements through the mediating background reference.
3Measurement precision
If multiple open-paths are scanned by a single spectrometer to obtain detailed emission information, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The single optical remote sensing system is designed to perform multiple functions: it can measure absorption spectra, emission spectra, and extinction coefficients using the same hardware platform. The system can scan multiple open-paths and acquire spectra in different configurations (sequential over defined path length, spatially adjacent directions, or from moving platforms), making the single device universal and eliminating the need for multiple specialized instruments.
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
This approach provides accurate and continuous monitoring of air contaminant concentrations by reducing noise and error, allowing for real-time updates and efficient detection of air contaminants along a defined path or spatially adjacent direction.
Implementation Method 1
Open-Path spectroscopic analyzers are used to provide quantitative information on a chemical mixture of gases and aerosol that propagate from emission sources
Implementation Method 2
The transmission is the ratio S(λ)/S0(λ) used to determine absorbance, emission or extinction
Implementation Method 3
calculating moving average sample and background values, and determining a moving average differential Double Beam value
Implementation Method 4
wavelength separator
Implementation Method 5
detector
Data Source
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AI summary
The subject matter discloses a method for detecting concentration of air contaminants, comprising obtaining an average sample single beam value, the average sample single beam value comprises a first set of single beam measurements obtained from a detector; obtaining an average background single beam value, the average background single beam value comprises a second set of single beam measurements obtained from the detector; comparing the average sample single beam value to the average background single beam value to determine the concentration of air contamination; continuously updating the averages upon detection of new single beam measurements; wherein the second set of single beam measurements comprises a plurality of single beam measurements that were detected by the detector prior to the detection of the single beam measurements included in the first set of single beam measurements. In some cases, the first set partially overlaps with the second set.