Rain gauge blockage detection method and device

Abstract

The invention belongs to the technical field of meteorological monitoring equipment, and discloses a rain gauge blockage detection method, which comprises the following steps of: installing a two-stage filter screen of a rain gauge, and arranging a wide-angle lens and a CCD (Charge Coupled Device) sensor; the monitoring system is started, and the CCD sensor transmits the filter screen image data to the remote operation and maintenance platform; performing image processing, and counting the number of light-transmitting bright spots and the area of the bright spots; and the remote operation and maintenance platform sends out an early warning signal according to the criterion, and after the operation and maintenance personnel clean the rain gauge, the monitoring system is started again to verify the cleaning effect so as to ensure that the filter screen returns to the normal state. The invention further discloses an anti-blocking rain gauge which comprises an outer cylinder and a two-stage filter screen, and the two-stage filter screen is arranged in the rain gauge. The bottom of the rain gauge is provided with a water outlet pipe. The rain gauge blockage monitoring method can be widely applied to rain gauge monitoring operation of various meteorological monitoring stations, and the operation and maintenance management level and the meteorological data quality of the rain gauge can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of meteorological monitoring equipment, and in particular relates to a rain gauge blockage detection method and device. Background Art

[0002] Rain gauges play an important role in photovoltaic applications of meteorological monitoring, but they face many problems in actual operation. Since the rain gauge is in an open environment, foreign objects such as dust, stones, and leaves can easily enter the rain gauge, resulting in frequent blockage of the rain gauge. Once the rain gauge is blocked, the accuracy of rainfall measurement cannot be guaranteed, which in turn affects the reliability and scientificity of meteorological data.

[0003] To ensure that the measuring instruments of the rain gauge are in good operating condition, the traditional solution is to increase the frequency of on-site maintenance. However, this approach will lead to a significant increase in operation and maintenance costs, including manpower, material resources, and time costs.

[0004] The existing method of detecting whether the rain gauge is operating normally mainly uses electrodes to issue an alarm when rain is detected. However, this method is only used to detect and repair the fault after it occurs, that is, when inaccurate measurement has occurred, which is a post-fault remedial measure.

[0005] Therefore, it is currently impossible to carry out effective prevention and early warning before a failure occurs, and it is difficult to meet the high requirements of modern meteorological monitoring for data accuracy and equipment reliability. Summary of the invention

[0006] To solve the above problems, the present invention provides a rain gauge blockage detection method to overcome the shortcomings of the prior art, achieve early perception and early warning of the rain gauge status, reduce operation and maintenance costs, improve the accuracy of monitoring data, and meet the reliability of equipment operation.

[0007] To achieve the above objectives, the present invention provides the following technical solutions.

[0008] An anti-clogging rain gauge comprises an outer cylinder and a two-stage filter screen, wherein the second-stage filter assembly is arranged inside the rain gauge; and a water outlet pipe is arranged at the bottom of the rain gauge; The two-stage filter screen includes a primary filter screen and a secondary filter column. The primary filter screen is a uniform mesh structure, and is located inside the rain gauge. A secondary filter column is arranged below the primary filter screen, and the secondary filter column passes through the outlet pipe of the rain gauge and is fixedly connected to the rain gauge. A first wide-angle lens is installed on the outer side of the top of the secondary filter column, and a first CCD sensor is arranged directly below the first wide-angle lens. A second wide-angle lens is installed on the inner side of the top of the secondary filter column, and a second CCD sensor is arranged directly above the second wide-angle lens. The first CCD sensor and the second CCD sensor convert the optical signal into an electrical signal, thereby generating a digital image signal; The first CCD sensor and the second CCD sensor are connected to the CPU, the CPU is connected to the data transmission module, and the data transmission module can transmit data to the remote operation and maintenance platform.

[0009] Furthermore, the secondary filter column includes a column, a two-stage filter screen, and a retaining ring. A two-stage filter screen is provided between the column and the retaining ring. The two-stage filter screen is a uniform mesh structure. A retaining ring is provided at the bottom of the secondary filter column. The secondary filter column passes through the outlet pipe and the retaining ring is located on the outlet pipe. The outer side of the outlet pipe is threadedly connected to the rainwater collecting pipe. During installation, the secondary filter column passes through the outlet pipe from bottom to top, and the retaining ring is located on the outlet pipe; then the outlet pipe is tightened with the rainwater collecting pipe thread to achieve the fixed connection of the secondary filter column to the bottom of the rain gauge.

[0010] Furthermore, a mounting ring is provided on the inner wall of the rain gauge, and the primary filter is arranged on the mounting ring, so that the primary filter can be detachably and conveniently installed in the rain gauge.

[0011] A method for detecting blockage of a rain gauge comprises the following steps: Step 1: Install the two-stage filter of the rain gauge, set up the wide-angle lens and CCD sensor; A two-stage filter is installed inside the rain gauge, the two-stage filter includes a primary filter and a secondary filter column, the primary filter is located above the secondary filter column, and the secondary filter column passes through the outlet pipe of the rain gauge and is fixedly connected to the rain gauge; A first wide-angle lens is installed on the outer side of the top of the secondary filter column, a first CCD sensor is arranged directly below the first wide-angle lens, a second wide-angle lens is installed on the inner side of the top of the secondary filter column, a second CCD sensor is arranged directly above the second wide-angle lens, the first CCD sensor and the second CCD sensor convert the optical signal into an electrical signal, and then generate a digital image signal; The first CCD sensor and the second CCD sensor are connected to the CPU, and the CPU is connected to the data transmission module, and the data transmission module can transmit data to the remote operation and maintenance platform; Step 2: Start the monitoring system; Start the monitoring system, the first wide-angle lens transmits the image information of the first filter to the first CCD sensor below it, and the first CCD sensor transmits the image data to the CPU through the data transmission module; At the same time, the second wide-angle lens transmits the image information of the secondary filter column to the second CCD sensor above it, and the second CCD sensor transmits the image data to the CPU through the data transmission module; Step 3: Image processing, counting the number and area of ​​light-transmitting bright spots; The CPU processes the image through image analysis algorithms; For the first-level filter image, count the number of light-transmitting bright spots and the bright spot area in the image; For the secondary filter column image, the number of light-transmitting bright spots and the bright spot area were counted in the same way; Step 4: The remote operation and maintenance platform issues an early warning signal based on the judgment criteria The remote operation and maintenance platform makes a judgment based on the preset alarm criteria. When the image data of the primary filter or the secondary filter column meets the alarm criteria, the remote operation and maintenance platform immediately issues an early warning signal; the criteria is that the number of bright spots or the bright spot area actually detected in step 3 is less than the threshold value; Step 5: After the operation and maintenance personnel clean the rain gauge, start the monitoring system again to verify the cleaning effect, ensure that the filter returns to normal, and ensure the accuracy of rainfall measurement.

[0012] Furthermore, the threshold is that the number of bright spots is less than N, where N is comprehensively determined by the filter shape, environment, and management requirements.

[0013] Furthermore, the threshold is that the bright spot area is less than A%, and A% is comprehensively determined by the filter shape, environment and management requirements.

[0014] Furthermore, the image analysis algorithm is based on the OpenCV image processing library to identify the number of bright spots and calculate the bright spot area. The specific method is: Preprocess the image data; remove incomplete images and images with poor clarity; Convert image data into grayscale image; The Gaussian algorithm is used to smooth the image and remove noise; the grayscale image is thresholded to separate the bright spot area, and the threshold segmentation point is set. When the pixel value is greater than 200, the pixel value is set to white, representing the bright spot area; when the pixel value is not greater than 200, the pixel value is set to black, representing the non-bright spot area; Use erosion and dilation operations to remove noise and spots in the image: perform erosion operations on the image in a 3*3 rectangular structure to expand the image; keep the shape and size of the bright spot area clearer and more complete; Use contour detection to find the bright spot area, traverse the detected contours, mark them, count the number of bright spots, and calculate the total area of ​​each bright spot area found.

[0015] Furthermore, the number of bright spots in the actual monitored image is counted as a percentage of the total number of bright spots in the grid in the image data, and an alarm is triggered when the trend reaches a preset value.

[0016] Where P(t) is the trend of the proportion changing with time; x(t) is the measured number of translucent bright spots changing with time; b(t) is the total number of translucent bright spots changing with time.

[0017] Furthermore, the changing trend of the bright spot area in the actual monitored image to the total grid area in the image data is counted, and an alarm is triggered when the changing trend reaches a preset value.

[0018] Where S(t) is the trend of the proportion changing with time; x(t) is the measured area of ​​the light-transmitting bright spot changing with time; b(t) is the total area of ​​the light-transmitting bright spot changing with time.

[0019] Furthermore, the early warning signal can be sent in various forms, such as text message notification to operation and maintenance personnel, pop-up warning boxes on the monitoring system interface, etc., so that the operation and maintenance personnel can know in time and take cleaning measures.

[0020] Working principle: (1) Light is irradiated onto the CCD sensor through a wide-angle lens, photons are absorbed and generate photogenerated charges. (2) The charges are converted into digital image data inside the CCD sensor. (3) The data transmission module receives the digital image data output by the CCD sensor and transmits it to the remote operation and maintenance platform through a wireless network for processing and analysis, to achieve alarm monitoring and realize "pre-event monitoring".

[0021] Beneficial effects: The monitoring method of the present invention can remotely monitor the two-stage filter status of the rain gauge under normal rainless conditions. Through accurate analysis of the number and area of ​​light-transmitting bright spots, it can determine in advance whether the rain gauge is at risk of blockage and send out an early warning signal, thereby avoiding the inaccurate measurement problem caused by the post-repair method of traditional monitoring, effectively reducing the workload and cost of personnel going to the site for periodic operation and maintenance, significantly improving the efficiency and reliability of rain gauge monitoring, and providing a strong guarantee for the accurate collection of meteorological monitoring data.

[0022] The rain gauge blockage monitoring method of the present invention can be widely used in rain gauge monitoring operations at various meteorological monitoring stations, whether in urban meteorological observation stations, rural meteorological monitoring points or field meteorological research facilities, and can effectively improve the operation and maintenance management level of rain gauges and the quality of meteorological data. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] Figure 2 It is a schematic diagram of the installation structure of the present invention.

[0025] Figure 3It is a schematic structural diagram of the secondary filter column of the present invention.

[0026] Figure 4 Schematic diagram of the monitoring system of the present invention.

[0027] In the figure: 1. outer cylinder; 2. primary filter screen; 3. secondary filter column; 31. column; 32. two-stage filter screen; 33. retaining ring; 4. water outlet pipe; 5. first wide-angle lens; 6. first CCD sensor; 7. second wide-angle lens; 8. second CCD sensor; 9. rainwater collecting pipe; 10. mounting ring. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Example

[0029] like Figures 1 to 4 The anti-clogging rain gauge shown in the figure comprises an outer cylinder 1 and a two-stage filter screen, wherein the two-stage filter screen is arranged inside the rain gauge; a water outlet pipe 4 is arranged at the bottom of the rain gauge; the two-stage filter screen comprises a primary filter screen 2 and a secondary filter column 3. The primary filter screen is a uniform mesh structure, which is located inside the rain gauge; a secondary filter column is arranged below the primary filter screen, which passes through the water outlet pipe of the rain gauge and is fixedly connected to the rain gauge.

[0030] The secondary filter column includes a column 31, a two-stage filter screen 32, and a retaining ring 33. A two-stage filter screen is arranged between the column and the retaining ring. The two-stage filter screen is a uniform mesh structure. A retaining ring is arranged at the bottom of the secondary filter column. The secondary filter column passes through the outlet pipe and the retaining ring is located on the outlet pipe. The outer side of the outlet pipe is threadedly connected to the rainwater collecting pipe 9.

[0031] A first wide-angle lens 5 is installed on the top outer side of the secondary filter column, and a first CCD sensor 6 is arranged directly below the first wide-angle lens. A second wide-angle lens 7 is installed on the top inner side of the secondary filter column, and a second CCD sensor 8 is arranged directly above the second wide-angle lens.

[0032] The first CCD sensor and the second CCD sensor convert the optical signal into an electrical signal, and then generate a digital image signal; the first CCD sensor and the second CCD sensor are connected to the CPU, the CPU is connected to the data transmission module, and the data transmission module can transmit the data to the remote operation and maintenance platform.

[0033] A mounting ring 10 is provided on the inner wall of the rain gauge, and the primary filter is arranged on the mounting ring, so that the primary filter can be detachably and conveniently installed in the rain gauge.

[0034] During installation, carefully install the first wide-angle lens so that it can completely cover the primary filter area, and install the first CCD sensor below the first wide-angle lens to ensure that the optical signal can be effectively transmitted and converted. At the same time, properly install the second wide-angle lens and the second CCD sensor in the position corresponding to the two-stage filter in the two-stage filter column so that it can completely cover the two-stage filter area. Connect the communication lines between the data transmission module and the two CCD sensors and the remote operation and maintenance platform to ensure stable and efficient data transmission. Accurately install the filter column in the middle position inside the rain gauge to ensure that it is stable and does not affect the normal collection of rainfall. Set the primary filter on the mounting ring to achieve a fixed connection, and the secondary filter column passes through the outlet pipe from bottom to top, and the retaining ring is located on the outlet pipe; then tighten the outlet pipe with the rain collection pipe thread to achieve a fixed connection between the secondary filter column and the bottom of the rain gauge.

[0035] When rainwater enters the rain gauge, it is first filtered through the primary filter to effectively intercept leaves, branches, impurities, etc.; then it is filtered through the two-stage filter of the secondary filter column to further intercept impurities, and then the rainwater enters the measuring element of the rain gauge from the outlet pipe and the rainwater collecting pipe to achieve measurement. Example

[0036] A method for detecting blockage of a rain gauge comprises the following steps: Step 1: Install a two-stage filter screen of a rain gauge, set a wide-angle lens and a CCD sensor; this is achieved by using the rain gauge of Example 1. Install a two-stage filter screen inside the rain gauge, install a first wide-angle lens on the top outer side of the secondary filter column, set a first CCD sensor directly below the first wide-angle lens, install a second wide-angle lens on the top inner side of the secondary filter column, and set a second CCD sensor directly above the second wide-angle lens. The first CCD sensor and the second CCD sensor convert the optical signal into an electrical signal, thereby generating a digital image signal; the first CCD sensor and the second CCD sensor are connected to the CPU, the CPU is connected to the data transmission module, and the data transmission module can transmit the data to the remote operation and maintenance platform.

[0037] Connect the communication lines between the data transmission module and the two CCD sensors, CPU, and remote operation and maintenance platform to ensure stable and efficient data transmission.

[0038] Step 2: Start the monitoring system; During daily periods without rainfall, the monitoring system is started according to the set time cycle. The first wide-angle lens transmits the image information of the first-level filter to the first CCD sensor below it, and the first CCD sensor transmits the image data to the CPU through the data transmission module. At the same time, the second wide-angle lens transmits the image information of the secondary filter column to the second CCD sensor above it, and the second CCD sensor transmits the image data to the CPU through the data transmission module.

[0039] Step 3: Image processing, counting the number and area of ​​light-transmitting bright spots; The CPU processes the image through an image analysis algorithm; for the first-level filter image, the number of light-transmitting bright spots and the bright spot area in the image are counted; for the second-level filter column image, the number of light-transmitting bright spots and the bright spot area are counted in the same way.

[0040] The image analysis algorithm is based on the OpenCV image processing library to identify the number of bright spots and calculate the bright spot area. The specific method is: Preprocess the image data; remove incomplete images and images with poor clarity; Convert image data into grayscale image; Gaussian algorithm is used to smooth the image and remove noise; The grayscale image is thresholded to separate the bright spot area. The threshold segmentation point is set. When the pixel value is greater than 200, the pixel value is set to white, representing the bright spot area; when the pixel value is not greater than 200, the pixel value is set to black, representing the non-bright spot area. Use erosion and dilation operations to remove noise and spots in the image: perform erosion operations on the image in a 3*3 rectangular structure to expand the image; keep the shape and size of the bright spot area clearer and more complete; Use contour detection to find the bright spot area, traverse the detected contours, mark them, count the number of bright spots, and calculate the total area of ​​each bright spot area found.

[0041] When there is no obstruction at all, the changing trend of the number of bright spots in the actual monitored image as a percentage of the total light-transmitting bright spots in the grid in the primary image data is counted, and an alarm is triggered when the changing trend reaches a preset value.

[0042]

[0043] Where P(t) is the trend of the proportion changing with time; x(t) is the number of measured light-transmitting bright spots x changing with time; b(t) is the number of total light-transmitting bright spots changing with time.

[0044] Count the changing trend of the bright spot area in the actual monitored image to the total grid area in the image data, and alarm when the changing trend reaches the preset value.

[0045] Where S(t) is the trend of the proportion changing with time; x(t) is the measured area of ​​the light-transmitting bright spot changing with time; b(t) is the total area of ​​the light-transmitting bright spot changing with time.

[0046] Step 4: Issue a warning signal based on the criteria According to the preset alarm criteria, when the image data of the primary filter or the secondary filter column meets the alarm criteria, the remote operation and maintenance platform immediately issues an early warning signal; the criteria is that the number of bright spots or the bright spot area actually detected in step 3 is less than the threshold; where the threshold is the number of bright spots less than N, and N is determined by the filter shape, environment, and management requirements. Wherein, the threshold is the bright spot area less than A%, and A% is determined by the filter shape, environment, and management requirements.

[0047] Step 5: After the operation and maintenance personnel clean the rain gauge, restart the monitoring system to verify the cleaning effect, ensure that the filter returns to normal, and ensure the accuracy of rainfall measurement. The early warning signal can be sent in various forms, such as SMS notification to the operation and maintenance personnel, pop-up warning boxes on the monitoring system interface, etc., so that the operation and maintenance personnel can know in time and take cleaning measures.

[0048] For example, the monitoring system is started every 4 hours. The first CCD sensor collects the image data of the first-stage filter transmitted by the wide-angle lens, and the second CCD sensor collects the image data of the second-stage filter, and sends the two sets of data to the CPU through the data transmission module. The image analysis algorithm of the CPU processes the received image data, counts the number and area of ​​the light-transmitting bright spots in the first-stage filter and the second-stage filter images, and compares them with the preset alarm criteria.

[0049] When the warning signal is issued, the operation and maintenance personnel will quickly go to the location of the rain gauge according to the notification and clean the blocked filter. After the cleaning is completed, the monitoring system will be started again to recheck the filter status. If the filter returns to normal, the operation and maintenance process is completed; if there is still an abnormality, continue to clean until the filter status meets the requirements, so as to ensure that the rain gauge can continuously and accurately measure rainfall.

[0050] The above are only preferred technical solutions of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements without departing from the principles of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A rain gauge for preventing clogging, characterized in that: It includes an outer cylinder and a two-stage filter screen, wherein the two-stage filter screen is arranged inside the rain gauge; a water outlet pipe is arranged at the bottom of the rain gauge; The two-stage filter screen includes a primary filter screen and a secondary filter column. The primary filter screen is a uniform mesh structure, and is located inside the rain gauge. A secondary filter column is arranged below the primary filter screen, and the secondary filter column passes through the outlet pipe of the rain gauge and is fixedly connected to the rain gauge. A first wide-angle lens is installed on the outer side of the top of the secondary filter column, and a first CCD sensor is arranged directly below the first wide-angle lens. A second wide-angle lens is installed on the inner side of the top of the secondary filter column, and a second CCD sensor is arranged directly above the second wide-angle lens. The first CCD sensor and the second CCD sensor convert the optical signal into an electrical signal, thereby generating a digital image signal; The first CCD sensor and the second CCD sensor are connected to the CPU, the CPU is connected to the data transmission module, and the data transmission module can transmit data to the remote operation and maintenance platform.

2. The rain gauge according to claim 1, characterized in that: The secondary filter column includes a column body, a two-stage filter screen, and a retaining ring. A two-stage filter screen is arranged between the column body and the retaining ring. The two-stage filter screen is a uniform mesh structure. A retaining ring is arranged at the bottom of the secondary filter column. The secondary filter column passes through a water outlet pipe and the retaining ring is located on the water outlet pipe. The outer side of the water outlet pipe is threadedly connected to the rainwater collecting pipe.

3. The rain gauge according to claim 1, characterized in that: A mounting ring is arranged on the inner side wall of the rain gauge, and the primary filter screen is arranged on the mounting ring.

4. A method for detecting a blockage of a rain gauge, characterized in that: The steps include: Step 1: Install the two-stage filter of the rain gauge, set up the wide-angle lens and CCD sensor; A two-stage filter is installed inside the rain gauge, the two-stage filter includes a primary filter and a secondary filter column, the primary filter is located above the secondary filter column, and the secondary filter column passes through the outlet pipe of the rain gauge and is fixedly connected to the rain gauge; A first wide-angle lens is installed on the outer side of the top of the secondary filter column, and a first CCD sensor is arranged directly below the first wide-angle lens. A second wide-angle lens is installed on the inner side of the top of the secondary filter column, and a second CCD sensor is arranged directly above the second wide-angle lens. The first CCD sensor and the second CCD sensor convert the optical signal into an electrical signal, thereby generating a digital image signal. The first CCD sensor and the second CCD sensor are connected to the CPU, and the CPU is connected to the data transmission module, and the data transmission module can transmit data to the remote operation and maintenance platform; Step 2: Start the monitoring system; Start the monitoring system, the first wide-angle lens transmits the image information of the first filter to the first CCD sensor below it, and the first CCD sensor transmits the image data to the CPU through the data transmission module; At the same time, the second wide-angle lens transmits the image information of the secondary filter column to the second CCD sensor above it, and the second CCD sensor transmits the image data to the CPU through the data transmission module; Step 3: Image processing, counting the number and area of ​​light-transmitting bright spots; The CPU processes the image through image analysis algorithms; For the first-level filter image, count the number of light-transmitting bright spots and the bright spot area in the image; For the secondary filter column image, the number of light-transmitting bright spots and the bright spot area were counted in the same way; Step 4: Issue a warning signal based on the judgment criteria. According to the preset alarm criteria, when the image data of the primary filter or the secondary filter column meets the alarm criteria, the remote operation and maintenance platform immediately issues an early warning signal; the criteria is that the number of bright spots or the bright spot area actually detected in step 3 is less than the threshold value; Step 5: After the operation and maintenance personnel clean the rain gauge, start the monitoring system again to verify the cleaning effect and ensure that the filter returns to normal.

5. The method according to claim 4, characterized in that: The threshold is that the number of bright spots is less than N, where N is determined by the filter shape, environment and management requirements.

6. The method according to claim 5, characterized in that: The threshold is that the bright spot area is less than A%, and A% is determined by the filter shape, environment and management requirements.

7. The method according to claim 5 or 6, characterized in that: The image analysis algorithm in step 3 is based on the OpenCV image processing library to identify the number of bright spots and calculate the bright spot area. The specific method is: Preprocess the image data; remove incomplete images and images with poor clarity; Convert image data into grayscale image; Gaussian algorithm is used to smooth the image and remove noise; The grayscale image is thresholded to separate the bright spot area. The threshold segmentation point is set. When the pixel value is greater than 200, the pixel value is set to white, representing the bright spot area; when the pixel value is not greater than 200, the pixel value is set to black, representing the non-bright spot area. Use erosion and dilation operations to remove noise and spots in the image: perform erosion operations on the image in a 3*3 rectangular structure to expand the image; keep the shape and size of the bright spot area clearer and more complete; Use contour detection to find the bright spot area, traverse the detected contours, mark them, count the number of bright spots, and calculate the total area of ​​each bright spot area found.

8. The method according to claim 7, characterized in that: Count the changing trend of the number of bright spots in the actual monitored image as a percentage of the total light-transmitting bright spots in the grid in the image data, and sound an alarm when the changing trend reaches the preset value ， Where P(t) is the trend of the proportion changing with time; x(t) is the measured number of translucent bright spots changing with time; b(t) is the total number of translucent bright spots changing with time.

9. The method according to claim 7, characterized in that: Count the changing trend of the bright spot area in the actual monitored image to the total grid area in the image data, and alarm when the changing trend reaches the preset value. ， Where S(t) is the trend of the proportion changing with time; x(t) is the measured area of ​​the light-transmitting bright spot changing with time; b(t) is the total area of ​​the light-transmitting bright spot changing with time.

10. The method according to claim 7, characterized in that: Early warning signals can be sent in a variety of forms, such as text messages notifying operation and maintenance personnel and popping up a warning box on the monitoring system interface.

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