Gas detection method, information processing device, information processing method, and laser gas detection device

Abstract

This technology provides a column density that corresponds to the gas concentration, enabling gas detection. [Solution] The gas in the measurement target area is detected by irradiating the area with laser light. In this method, a concentration distribution model of a gas cloud having a specific extent length L of gas is referenced, and the representative value of the gas concentration in the concentration distribution model and the threshold value of the gas column density for detecting the gas are obtained according to one input value.

Description

【Technical Field】 【0001】 The present invention relates to a gas detection method, an information processing apparatus, an information processing method, and a laser gas detector. 【Background Art】 【0002】 Conventionally, a laser gas detector using a laser has been known (see, for example, Patent Documents 1 and 2). In a laser gas detector, a gas is detected by collision of laser light with gas molecules, for example, methane molecules. Therefore, in a laser gas detector, since the number of gas molecules on the optical path of laser light is detected, the detection value of the gas is expressed in units of column density (for example, ppm·m). 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2018-169202 【Patent Document 2】 International Publication No. 2022 / 195673 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 On the other hand, conventionally, a concentration detection type gas detector for detecting the concentration of a gas in the atmosphere (for example, ppm) has been widely used. Since a laser gas detector detects gas molecules on the optical path of laser light, it has a sufficiently high detection sensitivity compared to a concentration detection type gas detector. 【0005】 However, the unit of the detection value of a laser gas detector is column density (ppm·m), which is essentially different from that (ppm) of a concentration detection type gas detector. In order to use a laser gas detector in place of a conventionally widely used concentration detection type gas detector, it is necessary that the detection value of the laser gas detector can be appropriately converted into the detection value of the concentration detection type gas detector. 【0006】 One aspect of the present invention aims to provide a technology that enables gas detection using a column density corresponding to the gas concentration. [Means for solving the problem] 【0007】 To solve the above problems, a gas detection method according to one aspect of the present invention is a method for detecting gas in a measurement target area by irradiating the area with laser light, and includes the step of obtaining, according to one input value, a representative value of the gas concentration in the concentration distribution model and a threshold value of the column density of the gas for detecting the gas, by referring to a concentration distribution model of a gas cloud having a specific extent length L of the gas. 【0008】 Furthermore, in order to solve the above problems, an information processing device according to one aspect of the present invention includes: a model acquisition unit that acquires a concentration distribution model of a gas cloud having a specific extent length L of gas; an information acquisition unit that, in response to an input of either a representative value of the gas concentration in the concentration distribution model or a threshold value for the column density of the gas for detecting the gas, refers to the concentration distribution model and acquires information on the other of the representative value and the threshold value; and a column density acquisition unit that refers to the scattered light signal of a laser beam irradiated onto the measurement target area and acquires information on the column density of the gas in the measurement target area. 【0009】 To solve the above problems, an information processing method according to one aspect of the present invention includes: a model acquisition step of acquiring a concentration distribution model of a gas cloud having a specific extent length L of gas; an information acquisition step of acquiring information on the other of a representative value of the gas concentration in the concentration distribution model and a threshold value of the column density of the gas for detecting the gas by referring to the concentration distribution model; and a column density acquisition step of acquiring information on the column density of the gas in the measurement target area by referring to the scattered light signal of a laser light irradiated onto the measurement target area. 【0010】 To solve the above problems, a laser-type gas detection device according to one aspect of the present invention is equipped with the above-mentioned information processing device. [Effects of the Invention] 【0011】 According to one aspect of the present invention, a technology can be provided that enables gas detection at a column density corresponding to the gas concentration. [Brief explanation of the drawing] 【0012】 [Figure 1] This diagram schematically shows one embodiment of the present invention. [Figure 2] This figure schematically shows a block diagram of an example of the functional configuration of a laser-type gas detection device according to one embodiment of the present invention. [Figure 3] This figure schematically shows an example of a gas cloud concentration distribution model in one embodiment of the present invention. [Figure 4] This diagram schematically shows an example of the functional configuration of an information processing device according to one embodiment of the present invention. [Figure 5] This flowchart shows an example of the processing flow in an information processing method according to one embodiment of the present invention. [Modes for carrying out the invention] 【0013】 The embodiments of the present invention will be described in more detail below. The embodiments of the present invention will be described using a configuration for detecting gas in an indoor space as an example. One embodiment of the present invention is schematically shown in Figure 1. 【0014】 As shown in Figure 1, there is an interior space 100 of a building. The building is, for example, a factory or warehouse, and the interior space 100 is, for example, a corridor, living room, or workshop. In the interior space 100, for example, a gas pipe 110 is located near the ceiling. Also, a laser-type gas detection device 1 is located at an arbitrary position on the floor of the interior space 100 (for example, a few centimeters above the floor). 【0015】 The gas pipe 110 is connected via the flange 140. If the gas (e.g., liquefied petroleum gas) flowing through the gas pipe 110 leaks from the flange 140, the gas will be distributed in the internal space 100. The collection of gas molecules thus distributed is referred to as the gas cloud 120. 【0016】 〔Laser Gas Detection Device〕 A block diagram of an example of the functional configuration of the laser gas detection device 1 is schematically shown in FIG. 2. As shown in FIG. 2, the laser gas detection device 1 includes an irradiation unit 11, a light receiving unit 12, a control unit 13, and a communication unit 14. 【0017】 The irradiation unit 11 is a device that irradiates laser light LB with a specific wavelength. The irradiation unit 11 includes, for example, an output adjustment unit 111 and a laser diode 112. 【0018】 The wavelength of the laser light LB irradiated by the irradiation unit 11 is the wavelength absorbed by the gas to be detected, and is determined according to the type of the gas to be detected. The type of the gas to be detected can be appropriately determined according to the application of the laser gas detection device 1. For example, if the application of the laser gas detection device 1 is for fire prevention, the gas to be detected may be a combustible gas, such as methane or propane. When the gas to be detected is, for example, methane gas, the wavelength of the laser light LB is, for example, 1.6 μm. The irradiation unit 11 is configured to be able to irradiate the laser light LB horizontally with respect to the floor surface of the internal space 100. 【0019】 The light receiving unit 12 is a device that receives the return light SL from the above atmosphere irradiated with the laser light LB. Examples of the return light SL include the laser light LB that has passed through the above atmosphere, its reflected light, and its diffusely reflected light. The light receiving unit 12 is a device that generates a signal according to the intensity of the received light, and is, for example, a photodiode (PD). The light receiving unit 12 is configured to detect the return light SL condensed by the light receiving lens 15, which is, for example, a condenser lens. 【0020】 The control unit 13 has a function of acquiring information on the detection result of the gas to be detected (hereinafter also referred to as "gas to be detected"), based on the detection signal of the light received by the light receiving unit 12, by referring to a specific threshold value of the column density of the gas to be detected for detecting the gas to be detected. In the present embodiment, the control unit 13 corresponds to the information processing apparatus in the present invention. The control unit 13 and the detection of the gas to be detected will be described in more detail later. 【0021】 The communication unit 14 has a function of receiving an input signal to the control unit 13 from the outside and transmitting an output signal from the control unit 13 to the outside. The communication unit 14 can be a functional configuration for known data transmission. 【0022】 The laser gas detection device 1 emits laser light LB into the internal space 100. The laser light LB is reflected by a reflecting portion such as a wall in the internal space 100, and the return light SL, which is scattered light reflected by the reflecting portion, is received via the light receiving lens 15. The laser gas detection device 1 detects gas molecules on the optical paths of the laser light LB and the return light SL from the detection value of the received return light SL, and outputs a detection value of the column density (ppm·m). 【0023】 〔Gas Detection Method〕 Gas can be detected by the laser gas detection device 1. The laser gas detection device 1 irradiates the measurement target area with laser light LB to detect the gas in the measurement target area. The measurement target area may be the internal space 100 itself or an arbitrary area determined by referring to laws and regulations. For example, the High-Pressure Gas Safety Act stipulates that one gas detection device should be installed every ten meters indoors. Therefore, the measurement target area 160 of the laser gas detection device 1 can be a prismatic area with a side length L of 2.5 m (perimeter length of 10 m) located directly below the flange 140 within the internal space 100. By setting the measurement target area 160 based on the current laws and regulations in this way, a threshold value equivalent to the threshold value in the gas detection of a conventional concentration detection type gas detection device that detects gas in terms of gas concentration (ppm) and is installed based on the High-Pressure Gas Safety Act can be set in the laser gas detection device 1. 【0024】 Next, the laser-type gas detection device 1 refers to a concentration distribution model of a gas cloud having a specific extent length L of gas. An example of a concentration distribution model of a gas cloud 120 in an embodiment of the present invention is schematically shown in Figure 3. The concentration distribution model shown in Figure 3 is a concentration distribution model of the gas cloud 120 in the horizontal direction. 【0025】 If the internal space 100 is a closed space, it can be assumed that the gas leaking out of the flange 140 and flowing down will have the highest concentration directly below the point of leakage, and that the gas concentration will decrease horizontally as it moves away from the point of leakage. Therefore, the concentration distribution model of the gas cloud 120 can be represented by a roughly triangular concentration distribution model 310 with the gas concentration below the point of leakage as its apex, as shown in Figure 3. 【0026】 In the figure, Cmax is the highest gas concentration in the concentration distribution model, and in the illustrated model, for example, it is the gas concentration directly below the leak point. Cmax is a representative value that represents the gas concentration in the concentration distribution model 310, which represents the horizontal gas concentration distribution. According to the High Pressure Gas Safety Act, one gas detection device is placed every 10 meters, and a threshold value for the measured value can be set in the gas detection device. Therefore, the concentration distribution model 310 of the measurement target area 160 can be related to the threshold value for the measured value in the gas detection device. The threshold value can be appropriately determined depending on the type of gas, but here, if the threshold value in a conventional concentration-detection type gas detection device is 10 ppm, then Cmax can be set to "10 ppm". 【0027】 On the other hand, gas detection devices generally have a detection limit. Therefore, gas concentrations below the detection limit have virtually no effect on the concentration distribution model 310. Thus, the concentration distribution model 310 is more accurately represented by a pentagon. In the figure, Cmin is the detection limit value for a concentration-sensing type gas detection device. When a gas detection device is installed at the edge of the measurement target area 160 and gas is detected, if Cmin is the lowest gas concentration that can be detected by the gas detection device, then the minimum concentration distribution model 310 for the measurement target area 160 at that time is represented by a pentagon. In this model, if the minimum value of the highest concentration to be detected, Cmax, and the length of the base, L can be given, the column density corresponding to those conditions can be determined. 【0028】 On the other hand, the unit of column density is ppm·m. Since the concentration distribution model 310 is represented by concentration (ppm) in the vertical direction and length (m) in the horizontal direction, the unit of the area D of the concentration distribution model 310 is ppm × m. Therefore, this area D becomes the threshold d when the gas cloud represented by the concentration distribution model 310 is measured by the laser gas detection device 1. This threshold d can be calculated from the following formula. d = L × {Cmin + (Cmax - Cmin) × 1 / 2} 【0029】 Here, L is the size (m) of the gas cloud 120 to be detected, determined, for example, by law; Cmin is the lower detection limit concentration (ppm) in the concentration-sensing gas detector; and Cmax is the highest gas concentration (ppm) in the smallest gas cloud 120 to be detected. When the laser-type gas detector 1 is applied to the same applications as a conventional concentration-sensing gas detector, Cmax may be the threshold value of the gas concentration detected in the concentration-sensing gas detector, and Cmin may be the lower detection limit value of the gas concentration in the concentration-sensing gas detector. Therefore, once the threshold value Cmax of the gas concentration is determined, the threshold value (ppm·m) of the laser-type gas detector 1 is determined based on the concentration distribution model 310. 【0030】 In this way, the laser-type gas detection device 1 acquires one input value based on the other: Cmax, which is a representative value of the gas concentration in the concentration distribution model 310 of the gas cloud 120, and the column density threshold for detecting the gas cloud 120. 【0031】 Therefore, given that the concentration distribution model 310 and Cmin are determined, if a certain value is input as the column density threshold d, the gas detected by the laser gas detection device 1 according to that threshold d is a gas that can constitute a gas cloud 120 having the highest gas concentration Cmax when distributed over a size of 2.5 m. 【0032】 Alternatively, given that the concentration distribution model 310 and Cmin are determined, if a certain value is input as the maximum gas concentration Cmax when the gas is distributed in a size of 2.5 m, the column density threshold of the laser gas detection device 1 that enables detection of the gas constituting the gas cloud 120 can be determined. 【0033】 Therefore, for example, if the gas detection threshold in a conventional concentration-detection type gas detection device is Cmax, then the gas constituting the gas cloud 120, where the conventional threshold is the highest gas concentration in the measurement target area 160, can be detected by the column density threshold d of the laser-type gas detection device 1. 【0034】 As described above, the gas detection method in this embodiment is a method for detecting gas in a measurement target area by irradiating the measurement target area with laser light, and includes a step of obtaining one of the following input values: a representative value of the gas concentration (Cmax) in the concentration distribution model 310 and a threshold value d for the column density of the gas to be detected, by referring to a concentration distribution model 310 of a gas cloud 120 having a specific extent length L of gas; and the other. Thus, in this embodiment, if the representative value Cmax is input, the threshold value d is determined, and if the threshold value d is input, the representative value Cmax is determined. Therefore, in this embodiment, by comparing the detected value obtained by irradiating the measurement target area 160 with laser light, the measured value of the column density, and the threshold value d in the concentration distribution model 310, gas corresponding to the gas cloud 120 can be detected in the measurement target area 160. 【0035】 Furthermore, if the representative value of the gas concentration is the maximum gas concentration Cmax in the gas cloud 120, the gas concentration distribution model can be simplified by a concentration distribution model 310 that includes Cmax. Therefore, it is preferable from the viewpoint of reducing the computational load and speeding up the processing if the representative value of the gas concentration is the maximum gas concentration Cmax in the gas cloud 120. 【0036】 Furthermore, by further referencing the minimum gas concentration in the gas cloud 120 (for example, the detection limit Cmin of the gas concentration in the concentration distribution model 310) to obtain the concentration distribution model 310, the concentration distribution model 310 becomes more limited, and calculations in parts that have little impact on the calculation of the threshold d can be omitted. Therefore, further referencing the minimum gas concentration Cmin in the gas cloud 120 when obtaining the concentration distribution model 310 is more preferable from the viewpoint of achieving both detection accuracy and low and high-speed computation. 【0037】 As described above, the laser-type gas detection device 1 of this embodiment uses Cmax as the gas detection threshold in a conventional concentration-detection type gas detection device, Cmin as the lower detection limit in the same concentration-detection type gas detection device, and L as a value based on the law. Therefore, it can be used for the same purposes as a conventional concentration-detection type gas detection device, i.e., for a gas detector installed in accordance with the law. 【0038】 The above gas detection method can be realized through the following information processing. 【0039】 [Information Processing Device] Figure 4 shows an example of the functional configuration of the control unit 13. As described above, the control unit 13 is one embodiment of an information processing device according to one embodiment of the present invention. 【0040】 As shown in Figure 4, the control unit 13 includes a model acquisition unit 131 that acquires a concentration distribution model of a gas cloud having a specific extent length L of the gas to be detected; an information acquisition unit 132 that, in response to one of the inputs of a representative value of the concentration of the gas to be detected in the concentration distribution model and a threshold value for the column density of the gas to be detected for detecting the gas, refers to the concentration distribution model and acquires the other information of the representative value and threshold value; and a column density acquisition unit 133 that refers to the signal of scattered light, i.e., reflected light SL, of the laser light irradiated onto the measurement target area and acquires information on the column density of the gas to be detected in the measurement target area. 【0041】 Furthermore, the control unit 13 further includes a determination unit 134. The determination unit 134, for example, refers to a threshold for column density acquired by the information acquisition unit 132 and determines whether the column density information acquired by the column density acquisition unit 133 is greater than or equal to that threshold. 【0042】 Furthermore, the control unit 13 is further equipped with a storage unit 135. The storage unit 135 stores various types of data related to the detection of the target gas, such as data for detecting the target gas and data acquired through the detection of the target gas. 【0043】 [Information Processing Methods] The information processing method for detecting the target gas by the control unit 13 will be explained. Figure 5 shows an example of the information processing flow according to one embodiment of the present invention. 【0044】 In step S501, the model acquisition unit 131 acquires a concentration distribution model of the gas cloud of the target gas. For example, the model acquisition unit 131 acquires the aforementioned concentration distribution model of the horizontal gas cloud 120 stored in the memory unit 135. Alternatively, the model acquisition unit 131 acquires a concentration distribution model received from an external source via the communication unit 14. In this way, the model acquisition unit 131 acquires a concentration distribution model of a gas cloud having a specific extent length L of the target gas. Furthermore, the model acquisition unit 131 acquires the above concentration distribution model by further referring to the minimum value Cmin of the concentration of the target gas in the gas cloud. 【0045】 Next, in step S502, the information acquisition unit 132 acquires information on a representative value of the gas concentration or a threshold value for the column density of the gas. For example, the information acquisition unit 132 acquires the following from the storage unit 135: the threshold value for gas detection in a conventional concentration-detection type gas detection device stored in the storage unit 135 is Cmax of the aforementioned concentration distribution model; the lower detection limit value for gas detection in a conventional concentration-detection type gas detection device stored in the storage unit 135 is Cmin of the aforementioned concentration distribution model; and 2.5 (m) is the specific spread length L of the target gas to be detected based on the placement conditions of the gas detection device in conventional laws and regulations, such as the High Pressure Gas Safety Act (one per 10m perimeter). The information acquisition unit 132 then refers to the aforementioned formula stored in the storage unit 135 to acquire a threshold value d corresponding to the acquired concentration distribution model. In this way, the information acquisition unit 132 acquires information on the threshold value d of the column density of the target gas to be detected in response to the input of the representative value Cmax of the concentration of the target gas in the concentration distribution model. 【0046】 Next, in step S503, the column density acquisition unit 133 acquires the detected value of the column density of the target gas. For example, the column density acquisition unit 133 acquires the measured value of the column density (ppm·m) of the target gas detected by the light receiving unit 12, in accordance with the detection signal of the light received by the light receiving unit 12. In this way, the column density acquisition unit 133 acquires information on the column density of the target gas in the measurement target area by referring to the signal of scattered light from the laser light irradiated onto the measurement target area. 【0047】 Next, in step S504, the communication unit 14 transmits the acquired column density detection value. For example, if the laser gas detection device 1 has a display unit such as a liquid crystal monitor, the communication unit 14 transmits information of the column density detection value to the display unit for display. Alternatively, if the target gas concentration in the measurement area is constantly monitored by a monitor via a monitoring control PC, the communication unit 14 transmits the acquired column density detection value to the monitoring control PC. 【0048】 Next, in step S505, the determination unit 134 determines whether the detected column density is above a threshold. If the detected column density is above a threshold, the control unit 13 causes the communication unit 14 to transmit a warning signal to the outside in step S506. If the detected column density is below a threshold, the control unit 13 repeatedly performs the processes from steps S501 to S505. 【0049】 In this way, the control unit 13 enables the detection of the target gas, which can be detected at the gas detection threshold of a conventional concentration-sensing type gas detection device, using the laser-type gas detection device 1, which detects the target gas by column density. Therefore, the laser-type gas detection device 1 can be used for the same purposes as conventional concentration-sensing type gas detection devices. 【0050】 [Other Embodiments] In this invention, a representative value Cmax of the concentration of the target gas in the concentration distribution model of the target gas may be obtained according to the input value of a threshold d for the column density of the target gas used to detect the target gas. For example, by inputting a column density threshold d, a specific concentration distribution model and a representative value Cmax of the concentration of the target gas when detecting the target gas can be obtained. Therefore, this is effective for initial investigation of detection conditions. 【0051】 Obtaining a representative value Cmax according to the input value of threshold d is also effective when the conditions of the internal space 100 in the above embodiment change (or when the measurement area of ​​the gas to be detected changes). More specifically, when a laser gas detection device is installed in an openable and closable space such as a retractable warehouse to detect a gas to be detected, only the L value based on the law may differ. In such cases, it is preferable to obtain a representative value Cmax according to threshold d. Alternatively, when it is known that the laser gas detection device 1 can properly detect the gas to be detected, it may be possible to change or optimize only the concentration distribution model from the viewpoint of improving detection accuracy. In such cases as well, it is preferable to obtain a representative value Cmax according to threshold d. 【0052】 Furthermore, in the present invention, the representative value Cmax of the concentration of the target gas in the concentration distribution model of the target gas may be appropriately determined according to the concentration distribution model, and may be, for example, the average value of the concentration of the target gas in the measurement target area. In addition, the concentration distribution model of the target gas may include a gas concentration distribution model that includes a factor of the flow of the target gas, in addition to the horizontal gas concentration distribution model described above. 【0053】 Furthermore, the representative value Cmax and minimum value Cmin of the target gas concentration in the gas cloud do not have to be the threshold and detection limit of a conventional concentration-detection type gas detection device. The representative value Cmax and minimum value Cmin may be calculated values ​​obtained, for example, from a computer simulation of the gas behavior in the measurement target area, or they may be values ​​determined based on measured gas concentrations in the measurement target area. 【0054】 For example, in a concentration distribution model representing a flowing gas, if there are multiple maximum values ​​of gas concentration, the average value of each maximum value may be used as Cmax. Furthermore, there may be multiple Cmax values ​​within the range represented by the concentration distribution model. Similarly, if there are multiple minimum values ​​of gas concentration, the average value of each minimum value may be used as Cmin, and there may be multiple Cmin values. Such configurations are preferable from the viewpoint of simplifying the shape of the concentration distribution model and reducing the information processing load for gas detection. 【0055】 Furthermore, the specific extent length L of the target gas in the gas cloud concentration distribution model does not have to be a value based on legal provisions. The length L, like the representative value Cmax and minimum value Cmin mentioned above, may be a calculated value obtained, for example, from a computer simulation of the gas behavior in the measurement target area, or it may be a value determined based on measured gas concentrations in the measurement target area. 【0056】 Furthermore, the laser gas detection device 1 may have configurations other than those described above in the previous embodiment, within the scope of achieving the effects of the present invention. For example, the laser gas detection device 1 does not have to be fixed to the internal space 100, and may be configured to be portable by an operator. Such a portable laser gas detection device can be used to detect unknown gas leak locations throughout the entire gas facility. The portable laser gas detection device can measure along the gas pipe. Therefore, for example, by setting the flange at the joint of the gas pipe as a location where gas leakage is expected (virtual leak point), and setting a representative value (maximum value) Cmax at the virtual leak point in the case of the horizontal gas cloud concentration distribution model described above, gas detection can be performed in the same manner as in the previous embodiment. 【0057】 Furthermore, the laser-type gas detection device of the present invention may further include an input device capable of inputting various parameters such as a representative value Cmax, a threshold value d, and a specific spread length L of the gas to be detected. Various known input devices such as a dial (rotary selector), a keyboard, or a touch panel can be applied to the input device. Having an input device in the laser-type gas detection device is preferable from the viewpoint that it is possible to input and change various parameters at the detection site, thereby enabling detailed setting of gas detection conditions according to the conditions around the virtual leak point. 【0058】 Furthermore, if the laser gas detection device of the present invention has an input device, it is preferable to also have a display unit such as the aforementioned liquid crystal monitor, from the viewpoint of confirming the input content and referring to various information during input. 【0059】 Furthermore, the laser-type gas detection device of the present invention may further include a distance measuring device. The distance measuring device is, for example, a device capable of measuring the distance from the laser-type gas detection device to a specific position in the detection target area, such as a virtual leak point, and may be a known distance measuring device such as a laser measuring instrument. Having a distance measuring device in the laser-type gas detection device makes it possible to appropriately set a specific spread length L of the detection target gas according to a specific distance, such as from the laser-type gas detection device to the virtual leak point when gas is detected by the laser-type gas detection device. Therefore, it is preferable from the viewpoint of making it possible to appropriately set the length L according to the conditions around the virtual leak point. 【0060】 Furthermore, the laser gas detection device of the present invention does not necessarily have the communication unit 14 described above. For example, if the detection conditions and detection results of the laser gas detection device can be directly confirmed from the laser gas detection device, then the setting of gas detection conditions, implementation, and confirmation of detection results can be performed even without a communication unit. 【0061】 The laser-type gas detection device 1 may further include an alarm transmitter that generates sound, such as a speaker, and may output a warning signal, such as a warning sound, from the alarm transmitter when the column density of the gas to be detected is equal to or greater than a threshold d. 【0062】 [Other embodiments relating to information processing] In the present invention, the function of the laser gas detection device 1 (hereinafter referred to as "device") is a program for causing a computer to function as the device, and can be realized by a program for causing a computer to function as each control block of the device (particularly each part included in the control unit 13). 【0063】 In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, the functions described in each of the embodiments above are realized. 【0064】 The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium. 【0065】 Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer. 【0066】 Furthermore, each process described in the above embodiments may be performed by AI (Artificial Intelligence). In this case, the AI ​​may operate on the control device described above, or it may operate on other devices (for example, an edge computer or a cloud server). 【0067】 〔summary〕 A first aspect of the present invention is a method for detecting gas in a measurement target area (160) by irradiating the area with laser light (LB), the method comprising the step of obtaining, by referring to a concentration distribution model (310) of a gas cloud (120) having a specific extent length L of gas, a representative value of the gas concentration in the concentration distribution model (Cmax) and a threshold value (d) of the gas column density for gas detection, one of which is an input value. According to the first aspect, gas can be detected at a column density corresponding to the gas concentration. 【0068】 A second aspect of the present invention is that, in the first aspect, the representative value of the gas concentration is the highest gas concentration in the gas cloud. In the second aspect, the concentration distribution model of the gas to be detected is simplified by a concentration distribution model that includes Cmax. Therefore, it is even more effective from the viewpoint of reducing the computation load and speeding up the processing. 【0069】 A third aspect of the present invention is that, in the first or second aspect, the gas detection method further includes a step of obtaining a concentration distribution model by referring to the minimum gas concentration (Cmin) in the gas cloud. In the third aspect, the concentration distribution model can be further limited and simplified because Cmin is further input. Thus, it is more effective from the viewpoint of reducing the computation load and speeding up the processing and improving the accuracy of gas detection. 【0070】 A fourth aspect of the present invention is an information processing device comprising: a model acquisition unit (131) that acquires a concentration distribution model of a gas cloud having a specific gas extent length L; an information acquisition unit (132) that, in response to an input of either a representative value of the gas concentration in the concentration distribution model or a threshold value for the gas column density for detecting the gas, refers to the concentration distribution model to acquire information on the other of the representative value and the threshold value; and a column density acquisition unit (133) that refers to the scattered light signal of a laser beam irradiated onto the measurement target area to acquire information on the gas column density in the measurement target area. According to the fourth aspect, gas can be detected at a column density corresponding to the gas concentration. 【0071】 A fifth aspect of the present invention is that the model acquisition unit acquires a concentration distribution model by further referencing the minimum gas concentration in the gas cloud. The fifth aspect is even more effective, as with the third aspect, in terms of reducing the computation load and speeding up the processing, and improving the accuracy of gas detection, because the concentration distribution model is further limited since Cmin is further referenced. 【0072】 A sixth aspect of the present invention is an information processing method comprising: a model acquisition step of acquiring a concentration distribution model of a gas cloud having a specific extent length L of the gas; an information acquisition step of acquiring information on the other of a representative value and a threshold value of the gas column density for detecting the gas, by referring to the concentration distribution model in response to an input of one of the following: a representative value of the gas concentration in the concentration distribution model and a threshold value of the gas column density for detecting the gas; and a column density acquisition step of acquiring information on the gas column density in a measurement target area by referring to the signal of scattered light from a laser beam irradiated onto the measurement target area. According to the sixth aspect, the gas can be detected at a column density corresponding to the gas concentration. 【0073】 A seventh aspect of the present invention is a laser-type gas detection device comprising an information processing device according to the fourth or fifth aspect. According to the seventh aspect, gas can be detected at a column density corresponding to the gas concentration. 【0074】 According to the present invention, a laser-type gas detection device, which has a sufficiently high detection sensitivity compared to conventional concentration-detection type gas detection devices, can be applied to the same applications as conventional concentration-detection type gas detection devices. In addition, since the above application is achieved by processing the detected values ​​in the present invention, it can also be repurposed for applications that have advantages in detecting gas at column density, and for example, it is possible to detect gas leakage itself before it reaches a threshold. The present invention, which has such effects, is expected to contribute to achieving goals such as Goal 9 of the United Nations Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation." 【0075】 The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols] 【0076】 1. Laser-type gas detection device 11 Irradiation area 12 Light receiving part 13 Control Unit 14 Communications Department 15. Light-receiving lens 100 interior space 110 gas pipe 111 Output adjustment section 112 Laser Diode 120 Gas clouds 131 Model Acquisition Section 132 Information Acquisition Department 133 Column Density Acquisition Unit 134 Judgment section 135 Storage section 140 flange 160 Measurement target area 310 Concentration Distribution Model LB laser light SL (steam locomotive) return light

Claims

[Claim 1] A method for detecting gas in a measurement target area by irradiating the area with laser light, The process includes a step of obtaining, by reference to a concentration distribution model of a gas cloud having a specific extent length L of the gas, a representative value of the gas concentration in the concentration distribution model, and a threshold value for the column density of the gas for detecting the gas, one of which is an input value, the other of which is an input value. Methods for detecting gases. [Claim 2] The gas detection method according to claim 1, wherein the representative value of the gas concentration is the highest value of the gas concentration in the gas cloud. [Claim 3] The gas detection method according to claim 1, further comprising the step of obtaining the concentration distribution model by referring to the lowest concentration of the gas in the gas cloud. [Claim 4] A model acquisition unit that acquires a concentration distribution model of a gas cloud having a specific gas extent length L, An information acquisition unit that, in response to an input of either a representative value of the gas concentration in the concentration distribution model or a threshold value for the column density of the gas for detecting the gas, refers to the concentration distribution model and acquires the other information of the representative value and the threshold value. A column density acquisition unit that acquires information on the column density of the gas in the measurement target area by referring to the scattered light signal of the laser light irradiated onto the measurement target area, An information processing device equipped with the following features. [Claim 5] The information processing apparatus according to claim 4, wherein the model acquisition unit acquires the concentration distribution model by further referring to the lowest value of the gas concentration in the gas cloud. [Claim 6] A model acquisition step to obtain a concentration distribution model of a gas cloud having a specific gas extent length L, An information acquisition step in which, in response to input of either a representative value of the gas concentration in the concentration distribution model or a threshold value for the column density of the gas for detecting the gas, information of the other of the representative value and the threshold value is obtained by referring to the concentration distribution model, A column density acquisition step involves obtaining information on the column density of the gas in the measurement target area by referring to the scattered light signal of the laser light irradiated onto the measurement target area, Information processing methods, including those mentioned above. [Claim 7] A laser-type gas detection device comprising the information processing device described in claim 4 or 5.

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