CFST arch bridge concrete pouring pressure regulation and control method based on infrared vision

Abstract

The invention discloses a CFST arch bridge concrete pouring pressure regulation and control method based on infrared vision, and the method comprises the steps: building a concrete liquid level-pipe pressure calculation model through an infrared vision positioning method, determining a pipe blocking risk grading model through the calculation model, and carrying out the risk grading and risk early warning. And finally, the pressure of the pumping machine is regulated to a reasonable range in real time according to risk grading. According to the concrete liquid level-pipe pressure calculation model established through the infrared vision positioning method, the pumping pressure of the pumping machine can be automatically regulated and controlled in real time according to pipe pressure changes, risk assessment and early warning of pipe blocking are conducted, construction personnel can be conveniently guided to make regulation and control decisions, the purposes of reducing the pipe blocking risk and preventing the pipe blocking phenomenon are achieved, and the construction efficiency is improved. The problems that an existing regulation and control method is poor in real-time performance and low in accuracy rate are solved, and accurate monitoring and intelligent regulation and control of the concrete pouring process are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel tube concrete arch bridge construction, and relates to a pumping pressure control method in a steel tube concrete arch bridge pouring construction process. Background Art

[0002] As an excellent closed steel-concrete composite structure, the bearing capacity and local stability of the steel tube are improved by filling with concrete. At present, the concrete pumping jacking pouring method has become a common technology to ensure the compactness of the concrete in the tube. This construction method uses a pumping machine to press the concrete from the pump pipe to the slurry inlet on the steel tube arch rib, and then continuously pumps the concrete in the steel tube to the slurry outlet of the arch top. The concrete is naturally compacted by the pressure generated during the pouring process. However, due to the influence of concrete rheological properties and pumping rate, concrete pipe blockage and even pipe burst are prone to occur, which seriously hinders the progress of pouring construction, reduces the quality of concrete in the tube, and threatens the personal safety of construction workers. Therefore, in order to ensure the quality of concrete pumping pouring in the main arch tube, ensure pouring continuity, and avoid concrete pipe blockage and pipe burst accidents, it is necessary to adjust the concrete pumping pressure in real time during the pouring construction process. In mountainous areas with complex terrain and environment, due to factors such as high concrete strength, large volume, large height difference, long pump distance, and closed environment, there are certain technical difficulties in accurately controlling the concrete in the tube. The commonly used control method currently relies solely on the pressure feedback of the pumping machine hydraulic system to adjust the frequency of pumping propulsion. This method has the following technical defects in actual engineering applications: (1) Due to the long pumping distance and the complex pressure loss along the pump pipe and steel pipe, the pressure feedback of the pumping machine hydraulic system usually has a certain lag, resulting in insufficient real-time control. (2) Due to the large pumping height difference, the concrete in the pipe is prone to stopping or slowing down. However, relying solely on the pressure feedback data of the hydraulic system cannot accurately judge the risk of pipe blockage, which can easily cause local backlogs or sudden increases in resistance in the pipeline, and ultimately lead to pipe blockage and bursting due to the inability to effectively control. In summary, the existing control methods have certain limitations in terms of real-time control and risk warning assessment. There is an urgent need for a reliable and efficient method for controlling the pouring of concrete in pipes.

[0003] In view of this, the present invention is based on the patented technology entitled "An infrared visual positioning method for concrete pumping liquid level in a steel tube arch bridge" authorized on October 1, 2024 (patent number "ZL202410125151.3"), and proposes an innovative method for regulating the pressure of pipe pressure concrete pouring to solve the above-mentioned engineering problems. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The purpose of the present invention is to provide a CFST arch bridge concrete pouring pressure control method based on infrared vision, establish a concrete liquid level-pipe pressure calculation model through an infrared vision positioning method, and automatically control the pumping pressure of the pumping machine in real time according to the pipe pressure change, and perform pipe blockage risk assessment and early warning, so as to guide construction personnel to make control decisions, achieve the purpose of reducing the risk of pipe blockage and preventing pipe blockage, solve the problems of poor real-time performance and low accuracy of existing control methods, and realize accurate monitoring and intelligent control of the concrete pouring process.

[0006] (II) Technical solution

[0007] The technical solution adopted by the present invention includes three steps: first, a concrete level-pipe pressure calculation model is established through an infrared visual positioning method, and then a pipe blockage risk classification model is established through the calculation model to perform risk rating and risk warning, and finally, the pumping machine pressure is adjusted to a reasonable range in real time according to the risk classification. The specific operation steps are as follows:

[0008] (1) Establish an accurate concrete level-pipe pressure calculation model, which specifically includes the following steps:

[0009] ① Determination of prior calculation parameters. Before pouring concrete for steel tube concrete arch bridges, it is necessary to measure the working performance parameters and mechanical properties of concrete. Take the concrete sample to be poured, measure its slump S (cm), and calculate the adhesion coefficient K1 (Pa) and velocity coefficient K2 (Pa / m / s) of the inner wall of the pump pipe, as shown in formula (1).

[0010]

[0011] ② Concrete level positioning and pumping rate calculation. Select appropriate monitoring points to set up infrared thermal imaging cameras, and use a monitoring software system based on infrared vision methods to obtain the mileage M and elevation H of the concrete pumping level at a long distance, quickly and in real time. Considering that the liquid level pumping rate is slow during the concrete pouring process and the rate will not change significantly in a short period of time, the average value of the rate in the previous 1 minute is taken as the concrete pumping rate at the current moment. The horizontal pumping rate v at the current moment is calculated by formula (2): x (m / s) and the pumping rate v in the vertical direction h (m / s):

[0012]

[0013] In formula (2), M t (m) and M t-1 (m) represents the liquid level mileage at the current moment and the liquid level mileage 1 minute ago; H t (m) and H t-1(m) represents the liquid level at the current moment and the liquid level 1 minute ago respectively.

[0014] If the liquid level rise path within 1 minute is approximately regarded as a straight line, then the pumping rate v in the direction of the pipe axis perpendicular to the concrete liquid surface at the current moment is l (m / s) is calculated by formula (3):

[0015]

[0016] ③ Calculate the pressure at the inlet of the steel pipe. Since concrete is a non-Newtonian liquid, it is subjected to complex forces during the pumping process. Based on the Bingham plastic fluid model, this paper proposes a method for calculating the pumping pressure in a large-diameter steel pipe. The pressure at the inlet of the steel pipe is composed of the concrete head deadweight pressure and the pressure loss along the way. The concrete head deadweight pressure P g (MPa) is calculated by formula (4):

[0017] P g =γ c H0 (4)

[0018] In formula (4), γ c is the concrete density; H0 is the elevation from the steel pipe inlet to the liquid level.

[0019] The resistance loss along the concrete pumping in the steel pipe takes into account the pressure loss caused by yield stress and pipe wall friction. f (MPa), calculated by formula (5):

[0020]

[0021] In formula (5), τ y (Pa) is the yield shear stress of concrete; D(m) is the inner diameter of the steel pipe; η(Pa·m) is the plastic viscosity of concrete; k is the rheological coefficient of concrete, usually laminar flow, with k=4; L(m) is the arc distance from the slurry inlet of the steel pipe to the concrete liquid level along the axis of the steel pipe.

[0022] The pumping pressure P1 (MPa) at the slurry inlet of the steel pipe is expressed by formula (6):

[0023] P1=P g +P f (6)

[0024] ④ Calculate the pump inlet pressure of the pump pipe. During the pouring process, concrete needs to be unloaded from the tank truck to the pumping machine, and then enter the pump pipe from the pump inlet until it is transported to the slurry inlet on the arch rib steel pipe. The pump outlet of the pump pipe is connected to the slurry inlet of the steel pipe. According to the "Technical Code for Concrete Pumping Construction" JGJ / T 10-2011, the pressure loss of concrete in the pump pipe needs to take into account the resistance along the way from the pumping machine to the slurry inlet of the steel pipe. The on-site pump pipe layout path may include horizontal pipes, vertical pipes, curved pipes, and inclined upward pipes. For the convenience of calculation, the horizontal length of the pumping path is converted, and the horizontal pipe length l0 (m) does not need to be converted and is represented by Z1 (m).

[0025] The conversion formulas for the horizontal length of the vertical tube are shown in equations (7) and (8):

[0026]

[0027] Z3=l1 (8)

[0028] In formula (7), Z2(m) is the horizontal conversion length of the vertical upward pipe; l1(m) is the vertical length of the vertical pump pipe; d(mm) is the diameter of the pump pipe; and in formula (8), Z3(m) is the horizontal conversion length of the vertical downward pipe.

[0029] The horizontal conversion length Z4 (m) of the elbow is calculated by formula (9):

[0030]

[0031] In formula (9), β is the elbow angle of the elbow (rad); n is the number of elbows of the elbow; r is the bending radius of the elbow (m);

[0032] The horizontal conversion length Z5 (m) of the inclined upward pipe is calculated by formula (10):

[0033]

[0034] In formula (10), l2 (m) is the straight length of the inclined upward pipe; α (rad) is the inclination angle of the inclined upward pipe; d (mm) is the diameter of the pump pipe.

[0035] After obtaining the horizontal conversion length of the pump pipe according to equations (7) to (10), the pressure loss ΔP (MPa) along the concrete in the pump pipe is calculated, as shown in equation (11):

[0036]

[0037] In formula (11), d (mm) is the inner diameter of the pump pipe; K1 is the concrete adhesion coefficient; K2 is the speed coefficient; t2 / t1 is the ratio of the switching time of the pumping machine distribution valve to the piston pushing the concrete cycle time, which is generally taken as 0.3; v0 (m / s) is the average flow rate of concrete in the pump pipe, which is expressed by the formula Conversion: a0 is the ratio of the radial pressure of concrete to the axial pressure, generally taken as 0.9.

[0038] Finally, the pressure P2 at the pump inlet is calculated by formula (12). Thus, the concrete level-pipe pressure calculation model is established, and the total propulsion force exerted by the pump to push the current concrete is predicted, laying a theoretical foundation for pouring control.

[0039] P2=P1+ΔP(Z1+Z2+Z3+Z4+Z5) (12)

[0040] (2) After the concrete level-pipe pressure calculation model is established, the pipe blockage risk rating and early warning are carried out, which specifically includes the following steps:

[0041] ① Calculate the pipe blocking risk rating index. First, calculate the predicted pressure value P2 of the pumping machine and the pressure value P2 monitored by the hydraulic gauge. b The pressure difference δP is as shown in formula (13).

[0042] δP=P2-P b (13)

[0043] According to the size of δP, pipe blockage may occur with different risk levels. Therefore, the pipe blockage risk rating index R is calculated to represent the predicted probability of pipe blockage at the current moment, as shown in formula (14).

[0044]

[0045] ② Establish a pipe blockage risk rating model. According to the risk rating index R obtained by formula (14), a pipe blockage risk rating model T is established to perform pipe blockage risk rating on the perfusion process at the current moment, as shown in formula (15).

[0046]

[0047] Among them, level III to level I means that the risk of pipe blockage increases step by step.

[0048] ③ Carry out pipe blockage risk warning. Install the warning module on the pumping machine pressure control device to complete the warning of the perfusion process with different risk ratings. The warning module is a warning indicator device embedded with the risk rating model. According to formula (15), when the risk rating index R < 15%, the pipe blockage risk is assessed as level III, which is within the normal pressure fluctuation range, and the warning module indicator light is green; when the risk rating index R∈[15%,50%], the pipe blockage risk is assessed as level II, and a level II warning is issued, and the warning module indicator light is yellow; when the risk rating index R≥50%, the pipe blockage risk is assessed as level I, and a level I warning is issued, and the warning module indicator light is red.

[0049] (3) According to the established pipe blockage risk rating model, real-time perfusion control is performed. When the pressure difference δP < 0, it indicates that the monitoring pressure value P of the pumping machine at the current moment is b δP will be reduced rapidly. To ensure a continuous and stable pumping pressure during the perfusion process, the system will control the pumping machine to increase the pumping thrust by δP. When the pressure difference δP>0, if T=Level III, the system will not adjust the pumping pressure. If T=Level II, the system will control the pumping machine to reduce the pumping thrust by δP. If T=Level I, the system will immediately stop the pumping machine and wait for the pressure to drop to normal levels before continuing pumping.

[0050] The present invention has the following beneficial effects:

[0051] (1) An accurate concrete level-pipe pressure calculation model was established through remote infrared visual monitoring, enabling the system to predict the concrete pumping pressure at the current moment and perform real-time regulation based on the pressure difference. Compared with traditional manual regulation methods, this method has better real-time performance and can achieve automatic regulation, effectively ensuring the stability of the pouring process and preventing pipe blockage and bursting.

[0052] (2) A pipe blockage risk grading model was established, and the early warning module was linked to provide construction personnel with real-time risk feedback, which helped construction personnel to change the control strategy in a timely manner according to the early warning indicators and on-site conditions, thereby improving the flexibility and reliability of injection control. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1It is a flow chart of the CFST arch bridge pipe pressure concrete pouring control method based on infrared vision proposed by the present invention;

[0055] Figure 2 Schematic diagram of the layout of the pump pipe and the steel pipe in Example 1 of the present invention;

[0056] Figure 3 It is a system flow diagram of the perfusion regulation process in Example 2 of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0058] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0059] Example 1

[0060] A C60 steel tube concrete arch bridge with a clear span of 300m, a rise of 70m, and a pipe diameter of 0.9m is used as an embodiment of the present invention. Before pouring construction, the working performance parameters and mechanical property indicators of the concrete are measured. The concrete sample to be poured is taken to measure its slump S = 18cm, the plastic viscosity of the concrete η = 200Pa·m, the rheological coefficient of the concrete on the inner wall of the steel tube k = 4, and the yield stress τ y =1200Pa, and calculate the adhesion coefficient of the inner wall of the pump tube and the speed factor Select appropriate monitoring points to set up infrared thermal imaging cameras and use the monitoring software system to obtain the mileage M of the concrete pumping level 1 minute ago. t-1 =65.199m and elevation H t-1 =50.148m, the mileage of the concrete pumping level at the current moment M t =66.11m and elevation H t =50.481m, at this time, the arc distance from the steel pipe inlet to the concrete liquid surface is L = 90m, Figure 2 The pump pipe and steel pipe route diagram of this embodiment is shown. Then the pumping rate in the horizontal direction at the current moment is calculated. and the vertical pumping rate The pumping rate in the direction of the pipe axis perpendicular to the concrete liquid surface at the current moment is Further, calculate the concrete head deadweight pressure Pg =2430×(66.11-2)=0.156Mpa, then calculate the total resistance loss along the concrete pumping in the steel pipe The pumping pressure at the steel pipe inlet is P1 = 0.156 + 0.486 = 0.642 MPa. Furthermore, the pressure loss ΔP along the concrete in the pump pipe is calculated. The inner diameter of the pump pipe is 125 mm. The average flow rate of the concrete in the pump pipe is Then calculate the pressure loss along the pump pipe Then calculate the horizontal conversion length of the pump tube, such as Figure 2 As shown, the horizontal pipe length Z1 = 4 + 1.5 + 1 = 6.5 m, the vertical upward pipe horizontal conversion length Z2 = 4 × 3 = 12 m, the vertical downward pipe horizontal conversion length Z3 = 3.5 m, the curved pipe horizontal conversion length Horizontal conversion length of the inclined upward tube The total horizontal converted length of the pump pipe is Z=6.5+12+3.5+1.1+10.6=33.7m, and finally the predicted pressure value at the pump inlet of the pump pipe is P2=0.642+0.02×33.7=1.316Mpa.

[0061] Example 2

[0062] Based on Example 1, pipe blockage risk classification, early warning and regulation are carried out. Figure 3 The system flow diagram of the perfusion control process is shown. First, the monitoring system calculates the pressure difference between the predicted pressure and the monitored pressure at the pump inlet δP = 1.316-1.037 = 0.279Mpa, and then calculates the pipe blockage risk rating index. At this time, the pipe blockage risk is graded as Level II, the system control risk warning indicator light turns yellow, and the pumping machine is controlled to reduce the propulsion pressure by 0.279 MPa.

[0063] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A CFST arch bridge concrete pouring pressure control method based on infrared vision, characterized in that: The following steps are involved: Step (1): Establish an accurate concrete level-pipe pressure calculation model, including: ① Determination of prior calculation parameters; ② Concrete level positioning and pumping rate calculation; ③ Calculate the pressure at the slurry inlet of the steel pipe; ④Calculate the pump inlet pressure; Step (2): After establishing the concrete level-pipe pressure calculation model, conduct pipe blockage risk rating and early warning, including: ① Calculate the pipe blocking risk rating index; ② Establish a pipe blockage risk rating model; ③ Provide early warning of pipe blockage risks; Step (3): Perform real-time perfusion regulation based on the established pipe blockage risk rating model.

2. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 1 is characterized in that: The determination of the a priori calculation parameters in the step (1) includes: before the concrete pouring construction of the steel tube concrete arch bridge, measuring the working performance parameters and mechanical property indicators of the concrete, taking a concrete sample to be poured, measuring its slump S (cm), and calculating the adhesion coefficient K1 (Pa) and the velocity coefficient K2 (Pa / m / s) of the inner wall of the pump pipe, as shown in formula (1):

3. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 2 is characterized in that: The concrete level positioning and pumping rate calculation in step (1) include: selecting appropriate monitoring points to set up infrared thermal imaging cameras, using a monitoring software system based on infrared vision methods to obtain the mileage M and elevation H of the concrete pumping level at a long distance, quickly and in real time, taking the average value of the rate in the previous 1 minute as the concrete pumping rate at the current moment, and calculating the pumping rate v in the horizontal direction at the current moment by formula (2): x (m / s) and the pumping rate v in the vertical direction h (m / s): In formula (2), M t (m) and M t-1 (m) represents the liquid level mileage at the current moment and the liquid level mileage 1 minute ago; H t (m) and H t-1 (m) represents the liquid level at the current moment and the liquid level 1 minute ago respectively; If the liquid level rise path within 1 minute is approximately regarded as a straight line, then the pumping rate v in the direction of the pipe axis perpendicular to the concrete liquid surface at the current moment is l (m / s) is calculated by formula (3):

4. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 3 is characterized in that: The step (1) of calculating the pressure at the steel pipe inlet includes: based on the Bingham plastic fluid model, the pressure at the steel pipe inlet is composed of the concrete head deadweight pressure and the pressure loss along the way, and the concrete head deadweight pressure P g (MPa) is calculated by formula (4): P g =c c H0 (4) In formula (4), γ c is the concrete density; H0 is the height from the steel pipe inlet to the liquid level; The resistance loss along the concrete pumping in the steel pipe takes into account the pressure loss caused by yield stress and pipe wall friction. f (MPa), calculated by formula (5): In formula (5), τ y (Pa) is the yield shear stress of concrete; D (m) is the inner diameter of the steel pipe; η (Pa·m) is the plastic viscosity of concrete; k is the rheological coefficient of concrete, usually laminar flow, k=4; L (m) is the arc distance from the slurry inlet of the steel pipe to the concrete liquid level along the axis of the steel pipe; The pumping pressure P1 (MPa) at the slurry inlet of the steel pipe is expressed by formula (6): P1=P g +P f (6) 5. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 4 is characterized in that: The calculation of the pump inlet pressure of the pump pipe in the step (1) includes: the on-site pump pipe arrangement path includes a horizontal pipe, a vertical pipe, a curved pipe and an inclined upward pipe. For the convenience of calculation, the horizontal length of the pumping path is converted, wherein the horizontal pipe length l0 (m) does not need to be converted and is represented by Z1 (m); The conversion formulas for the horizontal length of the vertical tube are shown in equations (7) and (8): Z3＝l1 (8) In formula (7), Z2 (m) is the horizontal conversion length of the vertical upward pipe; l1 (m) is the vertical length of the vertical pump pipe; d (mm) is the diameter of the pump pipe; in formula (8), Z3 (m) is the horizontal conversion length of the vertical downward pipe; The horizontal conversion length Z4 (m) of the elbow is calculated by formula (9): In formula (9), β is the elbow angle of the elbow (rad); n is the number of elbows of the elbow; r is the bending radius of the elbow (m); The horizontal conversion length Z5 (m) of the inclined upward pipe is calculated by formula (10): In formula (10), l2 (m) is the straight length of the inclined upward pipe; α (rad) is the inclination angle of the inclined upward pipe; d (mm) is the diameter of the pump pipe; After obtaining the horizontal conversion length of the pump pipe according to equations (7) to (10), the pressure loss ΔP (MPa) along the concrete in the pump pipe is calculated, as shown in equation (11): In formula (11), d (mm) is the inner diameter of the pump pipe; K1 is the concrete adhesion coefficient; K2 is the speed coefficient; t2 / t1 is the ratio of the switching time of the pumping machine distribution valve to the piston pushing the concrete cycle time, which is generally taken as 0.3; v0 (m / s) is the average flow rate of concrete in the pump pipe, which is expressed by the formula Conversion; a0 is the ratio of the radial pressure of concrete to the axial pressure, generally taken as 0.9; Finally, the pressure P2 at the pump inlet is calculated by formula (12). Thus, the concrete level-pipe pressure calculation model is established, and the total propulsion force exerted by the pump to push the current concrete is predicted, laying a theoretical foundation for pouring control: P2=P1+ΔP(Z1+Z2+Z3+Z4+Z5) (12) 6. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 5 is characterized in that: The calculation of the pipe blocking risk rating index in step (2) includes: firstly calculating the predicted pressure value P2 of the pumping machine and the pressure value P2 monitored by the hydraulic gauge. b The pressure difference δP is as shown in formula (13): δP=P2-P b (13) According to the size of δP, pipe blockage may occur at different risk levels. Therefore, the pipe blockage risk rating index R is calculated to represent the predicted probability of pipe blockage at the current moment, as shown in formula (14):

7. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 6 is characterized in that: The step (2) of establishing a pipe blockage risk rating model includes: establishing a pipe blockage risk rating model T according to the risk rating index R obtained from formula (14), and performing a pipe blockage risk rating on the perfusion process at the current moment, as shown in formula (15). Among them, level III to level I means that the risk of pipe blockage increases step by step.

8. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 7 is characterized in that: The pipe blocking risk warning in step (2) includes: installing a warning module on the pumping machine pressure control device to complete the warning of the perfusion process with different risk ratings, the warning module is a warning indicator device embedded with a risk rating model. According to formula (15), when the risk rating index R is less than 15%, the pipe blocking risk is assessed to be level III, which is within the normal pressure fluctuation range, and the warning module indicator light is displayed in green; when the risk rating index R∈[15%,50%], the pipe blocking risk is assessed to be level II, and a level II warning is performed, and the warning module indicator light is displayed in yellow; when the risk rating index R≥50%, the pipe blocking risk is assessed to be level I, and a level I warning is performed, and the warning module indicator light is displayed in red.

9. The infrared vision-based CFST arch bridge concrete pouring pressure control method according to claim 8 is characterized in that: The step (3) includes: when the pressure difference δP < 0, indicating that the monitored pressure value P of the pumping machine at the current moment b δP will be reduced rapidly. To ensure a continuous and stable pumping pressure during the perfusion process, the system will control the pumping machine to increase the pumping thrust by δP. When the pressure difference δP>0, if T=Level III, the system will not adjust the pumping pressure. If T=Level II, the system will control the pumping machine to reduce the pumping thrust by δP. If T=Level I, the system will immediately stop the pumping machine and wait for the pressure to drop to normal levels before continuing pumping.

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