Gas leak detection and event selection based on spatial concentration variability and other event properties

Patent metadata

Field	Value
Publication number	US-2016011069-A1
Application number	US-201414326195-A
Country	US
Kind code	A1
Filing date	Jul 8, 2014
Priority date	Jul 8, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

This work provides event selection in the context of gas leak pinpointing using mobile gas concentration and atmospheric measurements. The main idea of the present approach is to use a moving minimum to estimate background gas concentration, as opposed to the conventional use of a moving average for this background estimation.

First claim

1 . A method for gas leak event detection and selection, the method comprising:
providing a series of gas concentration measurements c i indexed by an integer i; detecting peaks p i in the series of gas concentration measurements c i , wherein each peak p i has a corresponding amplitude a i ; computing a moving minimum mc i given by the minimum of c j , wherein j is an index in a range i−n min +k 1 ≦j≦i+k 1 , wherein n min is a moving minimum window width, and wherein k 1 ≦n min is a first window offset; computing a moving standard deviation σ i of mc j , wherein j is an index in a range i−n b +k 2 ≦j≦i+k 2 , wherein n b is a moving standard deviation window width, and wherein k 2 ≦n b is a second window offset; performing event selection by computing a ratio R i of peak amplitude a i at peak p i to the moving standard deviation σ i of at peak p i and selecting events that have R i exceeding a predetermined threshold condition; and providing selected events as an output.

2 . The method of claim 1 , wherein the performing event selection further comprises computing a width w i of the peak p i .

3 . The method of claim 2 , wherein the predetermined threshold condition is a predetermined curve defined in a w i −R i plane.

4 . The method of claim 3 , wherein the threshold curve is a line.

5 . The method of claim 1 , wherein the predetermined threshold condition is a predetermined value R*.

6 . The method of claim 1 , wherein the providing the series of gas concentration measurements c i comprises:
performing raw gas concentration measurements at several times from a moving vehicle; determining the series of gas concentration measurements c i from the raw gas concentration measurements and from knowledge of position (time) of the moving vehicle.

7 . The method of claim 6 wherein the series of gas concentration measurements c i has its points substantially equally spaced apart in position.

8 . The method of claim 6 wherein the performing event selection further comprises computing a width w i of the peak p i , and wherein the width w i is normalized by a speed of the moving vehicle.

9 . The method of claim 1 , wherein the detecting peaks p i comprises identifying data points having corresponding concentrations c i such that c i−1 ≦c i and c i+1 ≦c i .

10 . The method of claim 1 , wherein the detecting peaks p i comprises using a peak finding algorithm to identify peaks p i .

11 . The method of claim 10 , wherein the peak amplitude a i is provided by the peak finding algorithm.

12 . The method of claim 1 , wherein the peak amplitude a i is determined according to a i =c i −mc i .

Assignees

• Picarro Inc

Inventors

• Steele David
• Crosson Eric R
• Tan Sze Meng

Classifications

• G01N33/0004 Primary

  Gaseous mixtures, e.g. polluted air · CPC title

• G01M3/22

  for pipes, cables or tubes; for pipe joints or seals; for valves; {for welds; for containers, e.g. radiators} · CPC title

• G01M3/00 Primary

  Investigating fluid-tightness of structures · CPC title