River section water quality monitoring and sampling device and method based on water surface propellers

Abstract

The invention relates to a river section water quality monitoring and sampling device and method based on a water surface propeller. The river section water quality monitoring and sampling device comprises the water surface propeller, collecting bottle units, a fixing assembly used for fixing the collecting bottle units in batches and a negative pressure assembly used for extracting air in the collecting bottle units. According to the monitoring and sampling device, the semi-submersible water surface propeller is arranged, so that the monitoring and sampling device cannot roll over due to stormy waves and undercurrent and is suitable for river sections with complex water regimen, the collecting bottle is inversely buckled to enter the water surface, a water sample enters the bottle body through air exhaust of the negative pressure assembly, the thread fixing structure is simple, and the monitoring and sampling device is suitable for batch arrangement; after the water level of the bottle body reaches a certain degree, the bottle plug is automatically closed under the driving of the floating bag and is tightly closed under negative pressure, a water sample cannot enter a pipeline of the negative pressure assembly, and the water sample directly enters from the bottle opening and does not pass through the pipeline and a medium pump, so that the influence on subsequent collection caused by residual pollution is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of water quality monitoring, and particularly relates to a river cross-section water quality monitoring and sampling device and method based on a water surface thruster. Background Technique

[0002] With the acceleration of the industrialization and urbanization processes, as well as the extensive use of chemical fertilizers and pesticides in agricultural production, water bodies such as rivers and lakes are facing unprecedented pollution pressures. Water quality monitoring of rivers is of great significance. Since the sources of pollution are different, the positions of pollutants in the river cross-section are also different. Obviously, only monitoring at fixed points cannot meet the requirements.

[0003] When monitoring the water quality of a river cross-section, existing water quality monitoring and sampling devices generally carry out monitoring and sampling by a small unmanned boat carrying monitoring personnel. The Chinese invention patent with the application number 202111577376.5 discloses an air extraction type water quality sampling mechanism for water quality monitoring, which is installed on an unmanned boat. This sampling mechanism collects samples by setting a water sampling bottle and a negative pressure device. The disadvantages of this mechanism are as follows: Due to the possible presence of undercurrents, fast-flowing water, wind waves and other adverse conditions in the river cross-section (especially the longitudinal section), the small unmanned boat has a certain risk of capsizing; the fixed structure of its water sampling bottle is relatively complex and is not suitable for the collection requirements of a large number of samples; the bottle mouth of its water sampling bottle has no sealing structure and can only be closed by an electromagnetic valve, but this valve is not directly set at the bottle mouth, and it is easy to spill when the water sampling bottle is removed from the device; the distance between the air extraction port and the water inlet is relatively close, and it is difficult to monitor the water volume in the water sampling bottle. If the electromagnetic valve is not closed in time, as the unmanned boat shakes, the air extraction port is likely to suck the polluted water into the negative pressure pump, causing pollutants to remain inside the negative pressure pump and being not easy to clean. Summary of the Invention

[0004] The purpose of the present invention is to provide a river cross-section water quality monitoring and sampling device and method based on a water surface thruster to solve the above problems.

[0005] The present invention realizes the above purpose through the following technical solutions:

[0006] A river cross-section water quality monitoring and sampling device based on a water surface thruster, comprising

[0007] A water surface thruster: which is used to carry each component into the river, including a frame, a propulsion component, and a monitoring module;

[0008] A fixing component, which is used to fix the collection bottle unit, including a fixing frame and threaded holes penetrating through the surface of the fixing frame;

[0009] A water collection bottle unit for collecting water, comprising a bottle body inverted in a threaded hole and an air extraction pipe inserted into the bottle body. The bottle mouth of the bottle body is provided with an external thread structure corresponding to the threaded hole. The side surface of the air extraction pipe near the upper end is provided with a floating bladder, and the side surface near the bottom is provided with a bottle stopper.

[0010] A negative pressure assembly is connected to the bottom of each air extraction pipe for evacuating the water collection bottle unit one by one.

[0011] As a further optimized solution of the present invention, the water surface thruster further includes a floating box, a cross frame for supporting the floating box, a navigation and positioning module, a camera assembly, and a power supply unit. The floating box is used to generate buoyancy so that the water surface thruster has a load capacity. The navigation and positioning module is used to control the traveling direction of the water surface thruster, and the camera assembly is used to facilitate the operator to observe the situation.

[0012] As a further optimized solution of the present invention, the fixing frame is fixedly connected to the cross frame through a plurality of fixing members. The fixing frame is used to fix the bottle body. Especially after the bottle body is filled with samples, in order to improve the stability, the fixing frame needs to be connected by a plurality of fixing members.

[0013] As a further optimized solution of the present invention, the surface of the air extraction pipe is further provided with discontinuous guiding members. The guiding members are slidably connected to the inside of the bottle mouth and are used to limit the sliding direction of the air extraction pipe. By setting the guiding members for guiding, the air extraction pipe can slide vertically. Among them, the guiding members are discontinuous to prevent blocking the water flow when absorbing water.

[0014] As a further optimized solution of the present invention, a baffle is provided at the top of the air extraction pipe. Among them, the bottom part of the bottle body of the bottle bulges outward to form a convex part. The baffle enters the convex part after the floating bladder moves upward. The bottom of the air extraction pipe is threadedly connected with a sleeve. The sleeve is provided with a one-way valve plate facing the outside of the bottle mouth. This solution is used to further seal the water collection bottle unit after collecting the water sample. First, the floating bladder drives the air extraction pipe to move upward. When the bottle stopper enters the bottle mouth, the baffle enters the convex part. And because the floating bladder is airtight and forms a piston, under negative pressure, this piston drives the bottle stopper to further tighten the bottle mouth, and the negative pressure causes the floating bladder to expand and then block the convex part to prevent the collected water sample from sloshing into the air extraction pipe.

[0015] As a further optimized solution of the present invention, the negative pressure assembly includes a connecting rod provided on a frame and a sealing cylinder provided on the connecting rod. The sealing cylinder corresponds to the sleeve and is slidably sealed with each other. By setting the sealing cylinder, the sleeve has a guide and is connected to the negative pressure assembly for air extraction.

[0016] As a further optimized solution of the present invention, the negative pressure assembly further includes a negative pressure pump and a switching valve. The bottom of the sealing cylinder is communicated with the switching valve through a connecting pipe. The negative pressure pump and the switching valve are communicated through a negative pressure pipe, and a compensation valve is arranged on the negative pressure pipe. After the negative pressure pump extracts air, the switching valve connects different connecting pipes, so that each sampling bottle unit can collect independent water samples.

[0017] As a further optimized solution of the present invention, the switching valve includes a valve housing and a rotatably arranged valve core. Among them, through holes are opened on the circumferential surface of the valve housing and communicated with each connecting pipe. The valve core is driven to rotate by a stepping motor arranged on the valve housing, and a flow channel is arranged in the valve core. One outlet of the flow channel is communicated with the negative pressure pipe, and the other outlet is used to switch and dock with different through holes. The switching valve in this solution can be provided with a plurality of through holes on its circumferential surface. Its structure is simple, it can carry a large number of sampling bottle units, and the wiring is simple. Only one stepping motor is required, and there is no need to set solenoid valves one by one. The wiring is simple, and the requirement for waterproof ability is relatively low.

[0018] In order to apply the above monitoring and sampling device, the present invention also proposes a monitoring and sampling method, which includes the following steps:

[0019] S1: Use the water surface thruster to carry a number of sampling bottle units into the preset area of the river section to be monitored. Use the propulsion component of the water surface thruster to counter the undercurrent and wind and waves, so as to stay in the preset area. Directly monitor the water through the monitoring module to obtain the real-time water quality situation. If the water quality monitoring meets the preset standard, go to the next preset area. The indicators of the water quality situation at least include pH, water temperature, water depth, pressure, conductivity, dissolved oxygen, and chlorophyll a concentration;

[0020] S2: Sample the water body whose water quality monitoring does not meet the preset standard. Operate the negative pressure component to extract air from one of the sampling bottle units, so that water enters the bottle body. When the water level makes the floating bladder float, the bottle stopper closes the bottle mouth to complete the sampling of this area, and record the position and time;

[0021] S3: Monitor multiple points of the water body within the preset range upstream of this area. For the water body whose monitoring does not meet the preheating standard, use the negative pressure component to extract air and sample a new sampling bottle unit, and record the position and time, and so on until all the preset monitoring and sampling are completed.

[0022] The beneficial effects of the present invention are as follows:

[0023] The present invention is provided with a semi-submersible water surface thruster, which will not capsize due to wind waves and undercurrents, and is applicable to river sections with complex water conditions. The sampling bottle is inverted into the water surface, and the water sample is drawn into the bottle body by pumping air through the negative pressure component. The threaded fixing structure is simple and suitable for batch setting. After the water level in the bottle body reaches a certain level, the bottle stopper is automatically closed under the drive of the floating bladder and is tightly closed under negative pressure. The water sample will not enter the pipeline of the negative pressure component, and the water sample directly enters from the bottle mouth without passing through the pipeline and the medium pump, so as not to cause residual pollution and affect subsequent sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the front view of the present invention;

[0025] Figure 2 is the side sectional view of the present invention;

[0026] Figure 3 is the Figure 2 view in the direction of A-A of the present invention;

[0027] Figure 4 is the Figure 3 enlarged view of the structure of part B in the present invention;

[0028] Figure 5 is the Figure 2 enlarged view of the structure of part C in the present invention;

[0029] Figure 6 is the Figure 2 enlarged view of the structure of part D in the present invention;

[0030] Figure 7 is the Figure 3 enlarged view of the structure of part E in the present invention;

[0031] Figure 8 is the schematic sectional view of the guiding member of the present invention;

[0032] In the figure: 1. Water surface thruster; 11. Frame; 12. Cross frame; 13. Float box; 14. Navigation and positioning module; 15. Monitoring module; 16. Propulsion component; 17. Camera component; 18. Power supply unit; 2. Fixing component; 21. Fixing frame; 22. Threaded hole; 23. Fixing piece; 3. Sampling bottle unit; 31. Bottle body; 32. Bracket; 33. Protrusion; 34. Suction pipe; 35. Guiding member; 36. Bottle stopper; 37. Sleeve; 38. Check valve plate; 39. Floating bladder; 310. Baffle; 4. Negative pressure component; 41. Valve housing; 42. Valve core; 43. Stepper motor; 44. Connecting pipe; 45. Sealing cylinder; 46. Negative pressure pipe; 47. Negative pressure pump; 48. Connecting rod; 5. Compensation valve; 51. Valve body; 52. Valve block; 53. Side groove; 54. Spring. DETAILED DESCRIPTION OF THE INVENTION

[0033] The following further describes the present application in conjunction with the accompanying drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0034] Embodiment 1

[0035] As Figure 1-8 shown, a river cross-section water quality monitoring and sampling device based on a water surface thruster includes a water surface thruster 1, a collection bottle unit 3, a fixing component 2 for batch-fixing the collection bottle unit 3, and a negative pressure component 4 for extracting the air in the collection bottle unit 3.

[0036] The water surface thruster 1 is used to carry each component into the river and includes a frame 11, a propulsion component 16, and a monitoring module 15. The propulsion component 16 includes a number of propellers, which cooperate with each other for steering and traveling. In this solution, there are four, which are respectively arranged at the four corners of the frame 11, and the axial direction of the propellers is distributed at a 45° angle with the frame 11;

[0037] The fixing component 2 is used to fix the collection bottle unit 3 and includes a fixing frame 21 and threaded holes 22 penetrating through the surface of the fixing frame 21;

[0038] The collection bottle unit 3 is used to collect water and includes a bottle body 31 buckled in the threaded hole 22 and an air extraction pipe 34 inserted into the bottle body 31. The bottle mouth of the bottle body 31 is provided with an external thread structure corresponding to the threaded hole 22. The side surface of the air extraction pipe 34 near the upper end is provided with a floating bladder 39, and the side surface near the bottom is provided with a bottle stopper 36;

[0039] The negative pressure component 4 is connected to the bottom of each air extraction pipe 34 and is used to extract air from the collection bottle unit 3 one by one.

[0040] In this solution, by setting a semi-submersible water surface thruster 1, it will not be overturned by undercurrents and wind waves, and the bottle body 31 is buckled into the water surface. The negative pressure component 4 extracts air to make the water sample enter the bottle body 31. The threaded fixing structure is simple and suitable for batch setting. After the water level in the bottle body 31 reaches a certain level, the bottle stopper 36 is automatically closed under the drive of the floating bladder 39 and is tightly closed under negative pressure. The water sample will not enter the pipeline of the negative pressure component 4, and the water sample directly enters from the bottle mouth without passing through the pipeline and the medium pump, so there will be no residual pollution to affect subsequent collection.

[0041] The water surface thruster 1 further includes a floating box 13, a cross frame 12 for supporting the floating box 13, a navigation and positioning module 14, a camera assembly 17, and a power supply unit 18. The floating box 13 is used to generate buoyancy so that the water surface thruster 1 has a load capacity. The navigation and positioning module 14 is used to control the traveling direction of the water surface thruster 1, and the camera assembly 17 is used to facilitate the operator to observe the situation.

[0042] The fixing frame 21 is fixedly connected to the cross frame 12 through a plurality of fixing members 23. The fixing frame 21 is used to fix the bottle body 31. Especially after the bottle body 31 is filled with samples, in order to improve the stability, the fixing frame 21 needs to be connected by multiple fixing members. The structure of the fixing frame 21 is simple, and the threaded holes 22 are arranged in sequence.

[0043] The surface of the air extraction pipe 34 is also provided with a discontinuous guiding member 35. The guiding member 35 is slidably connected to the inside of the bottle mouth and is used to limit the sliding direction of the air extraction pipe 34. By setting the guiding member 35 for guiding, the air extraction pipe 34 can slide vertically. Among them, the guiding member 35 is discontinuous, and its side surface is provided with side grooves along the axial parallel direction, which does not block the water flow from entering during water absorption.

[0044] A baffle 310 is provided at the top of the air extraction pipe 34. Among them, the bottom of the bottle body 31 bulges outward to form a convex portion 33. After the floating bladder 39 moves upward, the baffle 310 enters the convex portion 33. The bottom of the air extraction pipe 34 is threadedly connected with a sleeve 37. The sleeve 37 is provided with a one-way valve plate 38 facing the outside of the bottle mouth. This solution is used to further seal the sampling bottle unit 3 after sampling water. First, the floating bladder 39 drives the air extraction pipe 34 to move upward. When the bottle stopper 36 enters the bottle mouth, the baffle 310 enters the convex portion 33. And because the floating bladder 39 is airtight and forms a structure similar to a piston together with the baffle 310, under negative pressure, this piston drives the bottle stopper 36 to further tighten the bottle mouth, and the negative pressure causes the floating bladder 39 to expand and then block the convex portion 33. The one-way valve plate 38 blocks the gas from entering the air extraction pipe 34, maintains a negative pressure in the bottle body 31, and then maintains a tight closed state to prevent the sampled water from sloshing into the air extraction pipe 34. When removing the sampling bottle unit 3, rotate the sleeve 37 to allow gas to enter the air extraction pipe 34 and the bottle body 31, and then the bottle stopper 36 and the air extraction pipe 34 can be pulled out to pour out the water sample for further testing.

[0045] After setting the convex portion 33, the bottle body 31 is not easy to place, so a bracket 32 can be set at the bottom of the bottle body 31.

[0046] The negative pressure assembly 4 includes a connecting rod 48 arranged on the frame 11 and a sealing cylinder 45 arranged on the connecting rod 48. The sealing cylinder 45 corresponds to the sleeve 37 and is slidably connected in a sealed manner. By setting the sealing cylinder 45, the sleeve 37 has guidance and is connected to the negative pressure assembly 4 for air extraction.

[0047] The negative pressure assembly 4 further includes a negative pressure pump 47 and a switching valve. The bottom of the sealing cylinder 45 is connected to the switching valve through a connecting pipe 44. The negative pressure pump 47 and the switching valve are connected through a negative pressure pipe 46. A compensation valve 5 is provided on the negative pressure pipe 46. After the negative pressure pump 47 pumps air, the switching valve connects to different connecting pipes 44 so that each sampling bottle unit 3 can collect independent water samples. The compensation valve 5 is opened by overcoming the pressure difference. After the sampling bottle unit 3 is closed, the negative pressure opens the compensation valve 5 to prevent the negative pressure pump 47 from idling. The compensation valve 5 includes a valve body 51, a valve block 52, and a spring 54. A side groove 53 is provided on the valve body 51 to facilitate the valve body 51 to open the compensation valve 5 when overcoming the spring 54.

[0048] The switching valve includes a valve housing 41 and a rotatably arranged valve core 42. Among them, through holes are provided on the circumferential surface of the valve housing 41 and are connected to the respective connecting pipes 44. The valve core 42 is driven to rotate by a stepping motor 43 provided on the valve housing 41. A flow channel is provided inside the valve core 42. One outlet of the flow channel is connected to the negative pressure pipe 46, and the other outlet is used to switch and dock with different through holes. The switching valve in this solution can be provided with a plurality of through holes on its circumferential surface. Its structure is simple, it can carry a large number of sampling bottle units 3, only one stepping motor 43 is required, there is no need to set solenoid valves one by one, the wiring is simple, and the difficulty of electrical waterproofing is relatively low.

[0049] In order to apply the above monitoring and sampling device, the present invention also proposes a monitoring and sampling method, including the following steps:

[0050] S1: Use the water surface thruster 1 to carry a number of sampling bottle units 3 into the preset area of the river section to be monitored. Use the propulsion assembly 16 of the water surface thruster 1 to counter the undercurrent and wind and waves to stay in the preset area. The center of gravity of the water surface thruster 1 is relatively low and it is not easy to capsize. Directly monitor the water through the monitoring module 15 to obtain the real-time water quality situation. If the water quality monitoring meets the preset standard, go to the next preset area. The indicators of the water quality situation at least include pH, water temperature, water depth, pressure, conductivity, dissolved oxygen, and chlorophyll a concentration. The monitoring module 15 also has a communication module and a storage module to store and transmit the monitoring data in real time;

[0051] S2: Sample the water body whose water quality monitoring does not meet the preset standard. Operate the negative pressure assembly 4 to pump air for one of the sampling bottle units 3 so that water enters the bottle body 31. When the water level causes the floating bladder 39 to float, the bottle stopper 36 closes the bottle mouth to complete the sampling of this area, and record the location and time;

[0052] S3: Monitor the water body at multiple points within a preset range upstream of this area. For the water body that fails to meet the preheating standard during monitoring, use the negative pressure component 4 to evacuate and collect a new sampling bottle unit 3, record the location and time, and so on until the collection of all preset monitoring is completed.

[0053] By conducting subsequent chemical analysis on water samples from different areas, it helps to locate the pollution source based on information such as composition and concentration. And this collection device can accommodate a large number of sampling bottle units 3, and the complexity of its attached structure will not increase linearly with the increase in the number of sampling bottle units 3, which helps to provide a large number of samples, determine the position of pollutants in the river section, and is conducive to finding and locating the pollution source.

[0054] The specific implementation method is as follows: Monitor the water quality through the monitoring module 15. When the standard is not met, the negative pressure pump 47 is turned on to extract the gas in the bottle body 31 and suck the water sample into the bottle body 31. After the water level in the bottle body 31 rises, the floating bladder 39 rises to drive the suction pipe 34 to rise, and the bottle stopper 36 enters the bottle mouth, and water no longer enters the bottle body 31. The negative pressure makes the bottle stopper 36 tightly plugged. During the next collection, the stepping motor 43 drives the valve core 42 to rotate so that the negative pressure flow channel is aligned with the next bottle body 31.

[0055] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A river section water quality monitoring sampling device based on a water surface propeller, characterized in that: include A surface propeller (1) is used to carry various components into a river, including a frame (11), a propulsion assembly (16), and a monitoring module (15); A fixing assembly (2), which is used to fix the collection bottle unit (3), comprising a fixing frame (21) and a surface threaded hole (22) penetrating the fixing frame (21); A collection bottle unit (3) is used for collecting water, comprising a bottle body (31) buckled in the threaded hole (22), an air extraction pipe (34) inserted into the bottle body (31), the bottle mouth of the bottle body (31) having an external thread structure corresponding to the threaded hole (22), a floating bag (39) being arranged on the side surface of the air extraction pipe (34) near the upper end, and a bottle stopper (36) being arranged on the side surface near the bottom; The negative pressure assembly (4) is connected to the bottom of each suction pipe (34) and is used to evacuate the collection bottle units (3) one by one.

2. The river section water quality monitoring sampling device based on a water surface propeller according to claim 1 is characterized in that: The water surface propeller (1) also includes a buoyancy box (13), a cross frame (12) for supporting the buoyancy box (13), a navigation and positioning module (14), a camera assembly (17), and a power supply unit (18).

3. The river section water quality monitoring sampling device based on a water surface propeller according to claim 2 is characterized in that: The fixed frame (21) is fixedly connected to the cross frame (12) via a plurality of fixing members (23).

4. The river section water quality monitoring sampling device based on a water surface propeller according to claim 1 is characterized in that: A discontinuous guide component (35) is also provided on the surface of the air extraction pipe (34), and the guide component (35) is slidably connected to the inside of the bottle mouth and is used to limit the sliding direction of the air extraction pipe (34).

5. The river section water quality monitoring sampling device based on a water surface propeller according to claim 1 is characterized in that: A baffle (310) is provided at the top of the air extraction pipe (34), wherein the bottom of the bottle body (31) protrudes outward to form a protruding portion (33), and the baffle (310) enters the protruding portion (33) after the float bag (39) moves upward. A sleeve (37) is threadedly connected to the bottom of the air extraction pipe (34), and the sleeve (37) is provided with a one-way valve plate (38) facing the outside of the bottle mouth.

6. The river section water quality monitoring sampling device based on a water surface propeller according to claim 5 is characterized by: The negative pressure assembly (4) comprises a connecting rod (48) arranged on the frame (11) and a sealing cylinder (45) arranged on the connecting rod (48), wherein the sealing cylinder (45) corresponds to the sleeve (37) and is sealingly and slidably connected to each other.

7. The river section water quality monitoring sampling device based on a water surface propeller according to claim 6 is characterized by: The negative pressure assembly (4) further comprises a negative pressure pump (47) and a switching valve. The bottom of the sealing cylinder (45) is connected to the switching valve via a connecting pipe (44). The negative pressure pump (47) and the switching valve are connected via a negative pressure pipe (46), and a compensation valve (5) is provided on the negative pressure pipe (46).

8. The river section water quality monitoring sampling device based on a water surface propeller according to claim 7 is characterized in that: The switching valve comprises a valve housing (41) and a rotatably arranged valve core (42), wherein a through hole is opened on the circumferential surface of the valve housing (41) and is connected to each connecting pipe (44), the valve core (42) is driven to rotate by a stepping motor (43) arranged on the valve housing (41), and a flow channel is arranged in the valve core (42), one outlet of the flow channel is connected to the negative pressure pipe (46), and the other outlet is used for switching to connect with different through holes.

9. A monitoring sampling method based on the monitoring sampling device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: A plurality of collection bottle units (3) are carried by a water surface propeller (1) into a preset area of ​​a river section to be monitored, and the propulsion component (16) of the water surface propeller (1) resists undercurrents and wind and waves to stay in the preset area, and the water is directly monitored by a monitoring module (15) to obtain real-time water quality conditions. If the water quality conditions meet the preset standards, the water goes to the next preset area, wherein the water quality indicators at least include pH, water temperature, water depth, pressure, conductivity, dissolved oxygen, and chlorophyll a concentration; S2: For water bodies that do not meet the preset standards in water quality monitoring, sampling is performed, and air is pumped from one of the collection bottle units (3) through the operation of the negative pressure component (4), so that water enters the bottle body (31). When the water level causes the float bag (39) to float up, the bottle stopper (36) seals the bottle mouth, completing the sampling of the area, and recording the position and time; S3: Monitor the water bodies within a preset range upstream of the area at multiple points. For water bodies that do not meet the preheating standard, vacuum the new collection bottle unit (3) through the negative pressure component (4), and record the position and time, and so on, until all preset monitoring and collection are completed.

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