A method for calculating the maximum resistance path of a mine ventilation system
By converting roadway frictional resistance into negative weights and using virtual nodes to process multi-source and multi-sink networks, the problems of loop air pressure imbalance and unidirectional loop in the calculation of the maximum resistance path of mine ventilation systems are solved, achieving wider applicability and accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2022-07-13
- Publication Date
- 2026-06-12
AI Technical Summary
The existing method for calculating the maximum resistance path of a mine ventilation system cannot meet the loop pressure balance under a fixed air volume condition, and conventional algorithms cannot handle cases with additional power sources and unidirectional loops, resulting in inaccurate calculation results.
The roadway friction resistance is converted into a negative value as the roadway weight. The path with the maximum resistance is calculated through the topology graph. Virtual nodes are used to convert the multi-source multi-sink network into a single-source single-sink network. When a unidirectional loop exists, the influencing branch is deleted and recalculated.
It enables accurate calculation of the maximum resistance path of a mine ventilation system under various conditions, has wider applicability, and avoids calculation errors caused by local circulation.
Smart Images
Figure CN115130262B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of intelligent ventilation technology in mines, specifically to a method for calculating the maximum resistance path of a mine ventilation system. Background Technology
[0002] The field of intelligent ventilation technology in mines has made significant progress, with research on intelligent algorithms for mine ventilation systems being particularly important. The maximum resistance path in a mine ventilation system, as a fundamental part of the network solution process and system adjustment, occupies a crucial position in intelligent algorithms for mine ventilation systems. However, currently, there is little research on methods for calculating the maximum resistance of mine ventilation systems, and existing calculation methods have certain shortcomings and cannot adequately meet the requirements for calculating maximum resistance.
[0003] According to the definition of the maximum resistance path in a mine ventilation system, it is the path with the greatest sum of frictional resistance and local resistance generated during the airflow from the intake shaft to the main fan ventilation shaft. However, in practice, the following problems exist when calculating it using a computer: ① Under normal conditions, the ventilation system network is a balance diagram, where the maximum resistance path can be any path from the intake shaft to the return shaft. However, when solving the network for a ventilation system with a fixed air volume, the fixed air volume makes it impossible to satisfy the loop pressure balance law, thus making it impossible to calculate the maximum resistance path by arbitrarily selecting a path. ② Existing methods for calculating the maximum resistance path mostly use Dijkstra's algorithm. However, since its pathfinding strategy is greedy, simply changing its discrimination conditions cannot be applied to the calculation of the maximum resistance path. ③ Due to the influence of additional power sources such as the installation of local ventilation fans, fire sources or gas outbursts during disasters, and auxiliary ventilation methods in multi-stage stations in metal mines, conventional algorithms cannot calculate the maximum resistance path when there are unidirectional loops in the ventilation system.
[0004] Currently, there is no universally applicable method for calculating the maximum resistance path. Accurately calculating the maximum resistance path under multiple conditions is of great significance for realizing the intelligentization of ventilation systems. Summary of the Invention
[0005] To address the shortcomings of existing calculation methods, this invention provides a method for calculating the maximum resistance path of a mine ventilation system, which can effectively solve the problem that conventional algorithms cannot calculate the maximum resistance path in certain situations.
[0006] The technical solution adopted by this invention to solve its technical problem is as follows:
[0007] A method for calculating the maximum resistance path of a mine ventilation system includes the following steps:
[0008] Step 1: Establish the topological relationship of the mine ventilation system according to the mine ventilation system diagram;
[0009] Step 2: Use the negative value of the roadway friction resistance as the roadway weight to calculate the maximum resistance path of the mine ventilation system;
[0010] Step 3: Initialize the weight parameters of each node. Select the starting node and the ending node of the topology graph, and initialize the node weights from the starting node to each node.
[0011] Step 4: Calculate the weights from the starting node to each node. Based on the roadway weights, calculate the weights from the selected starting node to each node in sequence. Use the absolute value of the weights from the starting node to the final node as the maximum path resistance value. Use the order of the branch numbers that update the node weights from the starting node to the final node according to the roadway weights as the maximum resistance path.
[0012] Step 5: Check the existence of a one-way loop in the diagram. If a one-way loop exists, further processing is required; otherwise, the final result can be output.
[0013] Furthermore, in step one, the mine ventilation system topology diagram includes the topological information of each roadway, which is distinguished by subscripts: roadway branch e i Branch number m i The starting node v corresponding to the roadway branch i The final node v corresponding to the roadway branch j Node number n i Roadway frictional resistance r i Air volume q in the alley i Roadway friction resistance h i Roadway weight W (e) i ), weight W (v) of the starting node of the roadway i ), weight W(v) of the end node of the roadway j ); the aforementioned tunnel branch e i Includes virtual branches, the starting node v corresponding to the roadway branch i Includes virtual nodes, the end node v corresponding to the roadway branch. j Includes virtual nodes.
[0014] Furthermore, in step two, the roadway friction resistance of each roadway is calculated according to formula (1).
[0015] (1)
[0016] Among them, h i For the roadway friction resistance, Pa;r i For the frictional resistance of the tunnel, N·S 2 / m8 ;q i For the air volume passing through the tunnel, m 3 / s,
[0017] The calculated result of the roadway friction resistance is converted into a negative value, and this is used as the roadway weight W(e) i To calculate the minimum weight path of the lane in the topology graph.
[0018] Furthermore, in step three, when the ventilation system has multiple air intake shafts or return air shafts, additional virtual nodes need to be added. The virtual nodes convert the graphical topology from a multi-source, multi-sink network to a single-source, single-sink network for path calculation. When virtual nodes exist, they are used to connect the virtual nodes with each air intake shaft or return air shaft to form a single-source, single-sink network, which is not actually a line.
[0019] Furthermore, the starting node is the starting node of the intake air shaft branch of the mine. If there are multiple intake air shafts, the added virtual node is selected as the starting node. The ending node is the ending node of the return air shaft branch of the mine. If there are multiple return air shafts, virtual nodes are added to assist in the calculation. When selecting the ending node, the ending nodes of the branches with return air shafts are selected sequentially as the ending nodes. The initial node weight of the starting node is 0, and the weights of the other nodes are all +. .
[0020] Furthermore, in step four, each branch is selected sequentially according to the branch numbering order in step one, and based on the roadway weight, the node weights from the selected starting node in the graph to each node in the topology graph are calculated sequentially.
[0021] First, calculate the weight W(v) of the current starting node. i ) and roadway weight W (e i Perform a summation operation; then sum the summation with the weight W(v) of the last node of the current branch. j Compare the result with W(v). i )+W(e i The weight W(v) of the last node is less than the weight of the last node. j Let the weight of the last node be W(v). j ) = W(v i )+W(e i Conversely, there is no need to update the weight of the last node. The process of summing and comparing is repeated by continuously selecting the next edge, and the branch numbers for correcting node weights with roadway weights are recorded sequentially, until all branches have performed relaxation calculations on the nodes, and all node weights in the graph are recalculated, judged, and updated.
[0022] Repeat step four above n-1 times, where n is the number of nodes in the graph, to finally obtain the weights of each node in the topological relationship graph from the starting node.
[0023] Furthermore, in step five, if the calculation result remains unchanged, it indicates that there is no unidirectional loop in the graph, and the maximum path resistance value and the maximum resistance path are output. Conversely, under the existing conditions, the existence of unidirectional loops in the graph causes the calculation result to fall into a local loop. The node weights are affected by the continuous accumulation of local roadway weights, ultimately leading to errors in the result. Corresponding changes need to be made and the calculation needs to be recalculated.
[0024] Furthermore, the calculation method also includes step six: if a one-way loop exists, find the branch that causes the one-way loop in the topology graph, delete the branch that causes the one-way loop and connects the last node of the branch, and then re-enter the calculation in step 4.
[0025] Compared with the prior art, the present invention has the following advantages: it has a wider applicability, not only applicable to the calculation of the maximum resistance path of the ventilation system under normal circumstances, but also applicable to the calculation of the maximum resistance path of the ventilation system under special circumstances where there is a unidirectional loop. Attached Figure Description
[0026] Figure 1 It is an algorithm flowchart.
[0027] Figure 2 This is an example network topology diagram of a ventilation system. Detailed Implementation
[0028] The present invention will now be clearly and completely described with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.
[0029] A method for calculating the maximum resistance path of a mine ventilation system, specifically including the following steps:
[0030] Step 1: Establish the topology of the mine ventilation system
[0031] Based on the actual mine ventilation system diagram, establish the topological relationships of the mine ventilation system, including the topological information of each roadway in the diagram. Distinguish roadways using subscripts: Roadway Branches (including virtual branches) e i Branch number m i The starting node (including virtual nodes) corresponding to the branch of the alleyway. i The end node (including virtual nodes) corresponding to the roadway branch v j Node number ni Roadway frictional resistance r i Air volume q in the alley i Roadway friction resistance h i Roadway weight W (e) i ), weight W (v) of the starting node of the roadway i ), weight W(v) of the end node of the roadway j ).
[0032] Virtual nodes: When there are multiple air intake shafts or return air shafts in the ventilation system, additional nodes that do not exist need to be added to transform the graphical topology from a multi-source, multi-sink network into a single-source, single-sink network for path calculation.
[0033] Virtual branch: When virtual nodes exist, it is used to connect the virtual nodes with each intake or return air shaft to form a single-source, single-sink network. It is a line that does not actually exist.
[0034] Step 2: Calculation of roadway weights
[0035] Since the calculation focuses on the maximum resistance path of the mine ventilation system, the frictional resistance of each roadway is used as the basis for calculating the roadway weight. The roadway frictional resistance is calculated according to the following formula:
[0036] (1)
[0037] Among them, h i For the roadway friction resistance, Pa;r i For the frictional resistance of the tunnel, N·S 2 / m 8 ;q i For the air volume passing through the tunnel, m 3 / s.
[0038] Since the algorithm is a process of finding the path with the minimum weight in the graph, in practical applications, the frictional resistance of the branches is calculated sequentially according to formula (1), the calculation result of the roadway frictional resistance is converted into a negative value, and this is used as the roadway weight W(e i This is used to calculate the path with the minimum lane weight in the topology graph, and then to find the path with the maximum resistance.
[0039] Step 3: Initialize the weight parameters of each node
[0040] Select the starting node and the ending node of the graph. The starting node is the beginning node of the intake air shaft branch of the mine (if there are multiple intake air shafts, select the added virtual node as the starting node). The ending node is the end node of the return air shaft branch of the mine (if there are multiple return air shafts, virtual nodes need to be added to assist in the calculation; however, when selecting the ending node, the ending nodes of the branches with return air shafts should be selected in sequence as the ending nodes).
[0041] Initialize the node weights from the starting node to each other: the starting node's weight is initially 0, and the weights of all other nodes are positive. .
[0042] Step 4: Calculate the weights from the starting node to each node.
[0043] Following the branch numbering order in Step 1, each roadway is selected sequentially. Based on the roadway weight, the node weights from the selected starting node in the graph to each node in the topology graph are calculated sequentially. First, the weight W(v) of the current starting node is calculated. i ) and roadway weight W (e i Perform a summation operation; then sum the summation with the weight W(v) of the last node of the current branch. j Compare the result with W(v). i )+W(e i The weight W(v) of the last node is less than the weight of the last node. j Let the weight of the last node be W(v). j ) = W(v i )+W(e i Conversely, there is no need to update the weight of the last node. The process of summing and comparing is repeated by continuously selecting the next edge, and the branch numbers for correcting node weights with roadway weights are recorded sequentially. This continues until all branches have performed relaxation calculations on the nodes, and all node weights in the graph are recalculated, judged, and updated.
[0044] Repeat step four above n-1 times, where n is the number of nodes in the graph, to obtain the weights of each node in the topology graph from the starting node. The absolute value of the weights from the starting node to the final node is used as the maximum path resistance value. The path with the maximum resistance is defined as the branch numbering that updates the node weights sequentially according to the roadway weights from the starting node to the final node.
[0045] Step 5: Verify the existence of a one-way loop in the diagram.
[0046] Based on the calculation results in step four, a relaxation calculation is performed on the weights of each node in the graph to verify whether there are unidirectional loops in the graph that interfere with the calculation results.
[0047] If the calculation results remain unchanged, it indicates that there is no unidirectional loop in the graph, and the maximum path resistance value and the path with the maximum resistance are output. Conversely, under the current conditions, the existence of unidirectional loops in the graph causes the calculation results to fall into a local loop, and the node weights are affected by the continuous accumulation of local roadway weights, ultimately leading to errors in the results. Therefore, it is necessary to make corresponding changes and recalculate.
[0048] Step Six: Special Handling of Unidirectional Loops
[0049] If a one-way loop exists, find the branch in the diagram that causes the one-way loop due to local fans, additional power sources, etc. Delete the branch that connects the last node of the one-way loop branch, and then re-enter step four of the calculation.
[0050] Example 1: A simplified network diagram of the ventilation system in a certain mine is shown below. Figure 2 As shown, there are two intake shafts, branched as e0 and e1; and two return shafts, branched as e12 and e15. Due to changes in the mining plan, a local ventilation fan was installed in branch e8, which changed the airflow direction in branch e9. The path of maximum resistance in the mine was calculated after the change in the airflow direction in branch e9.
[0051] Step 1: Establish the topology of the mine ventilation system
[0052] Analysis shows that the ventilation system is a multi-source, multi-sink network. To meet the computational requirements, two virtual nodes, numbered v10 and v12, are added first; four virtual branches, e13, e14, e16 and e17, are added to convert it into a single-source, single-sink network for computation.
[0053] The topology of the ventilation system network in this example is established. Data such as branch number, corresponding start and end node number of the branch, roadway frictional resistance, air volume, and roadway frictional resistance are shown in Table 1.
[0054] Table 1. Relevant Topology Information of a Mine Ventilation System
[0055]
[0056] Step 2: Calculation of roadway weights
[0057] The frictional resistance of each roadway is calculated according to formula (1), and the roadway frictional resistance is converted into roadway weight according to step two. The relevant data are shown in Table 2.
[0058] Table 2
[0059]
[0060] Step 3: Initialize the weight parameters of each node
[0061] Since this example is a multi-source, multi-sink ventilation system, adding virtual nodes and virtual branches transforms it into a multi-source, multi-sink ventilation system. Therefore, the starting node of the graph is selected as v10, and the ending nodes are v9 and v11. The weights of each node are initialized: the weight of node v10 is set to 0, and the initial weights of the remaining nodes 2 to 11 are set to +. .
[0062] Step 4: Calculate the weights from the starting node to each node.
[0063] According to step four and Figure 1 The algorithm flow shown is used for calculation. When v10 is the starting node and v9 and v11 are the final nodes, the calculation results are as follows:
[0064] From the starting node v10 → the weights of each node: [0, 0, -72.7, -412.6, -409.8, -13024.4, -14259.2, -15341.2, -16046.2, -16142.1, 0, -15754.5, -16142.1].
[0065] Step 5: Verify the existence of a one-way loop in the diagram.
[0066] Following the verification method for the correctness of the calculation results in step five, after recalculating the weights of each node in the graph, the results changed. Therefore, it can be determined that the unidirectional loops in the graph interfered with the calculation results. The recalculated result is as follows:
[0067] From the starting node v10 → the weights of each node: [0, 0, -72.7, -412.6, -409.8, -14310.0, -15544.8, -16626.8, -17331.8, -17427.7, 0, -17040.1, -17427.7].
[0068] Step Six: Special Handling of Unidirectional Loops
[0069] Analysis shows that the presence of the local ventilator causes branches e8, e9, and e6 to form a closed loop, trapping the program in a local optimal loop during the calculation. Therefore, adjustments are needed. Referring to the method in step six, identify the local ventilator branch in the unidirectional loop and delete the unidirectional loop branch connected to its final node, i.e., branch e9. Then, recalculate the path of maximum resistance.
[0070] The calculation results are as follows when v10 is the starting node and v9 and v11 are the ending nodes:
[0071] From the starting node v10 → weights of each node: [0, 0, -72.7, -412.6, -409.8, -1046.8, -996.0, -2078.0, -2783.0, -2878.9, 0, -2491.3, -2878.9];
[0072] The correctness of the maximum resistance path calculation was verified again, and it was found that the calculation result did not change. Therefore, the influence of the unidirectional loop on the maximum resistance path calculation was eliminated after deleting branch e9.
[0073] The maximum path resistance from the starting node v10 to the final node v9 is 2878.9;
[0074] The path with the greatest resistance from the starting node v10 to the final node v9 is: v10=>v1=>v3=>v6=>v7=>v8=>v9;
[0075] The maximum path resistance from the starting node v10 to the final node v11 is 2491.3;
[0076] The path with the greatest resistance from the starting node v10 to the final node v11 is: v10=>v1=>v3=>v6=>v7=>v11.
[0077] The results show that the method proposed in this invention is feasible and can effectively solve the problems of conventional algorithms being unable to calculate the maximum resistance path of a mine ventilation system due to the presence of negative weight edges and errors in the calculation results when a one-way loop occurs due to certain special reasons.
[0078] The above description is merely a calculation method described in this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.
Claims
1. A method for calculating the maximum resistance path of a mine ventilation system, characterized in that... The calculation method includes the following steps: Step 1: Based on the mine ventilation system diagram, establish a topology diagram of the mine ventilation system. This topology diagram includes the topological information of each roadway in the diagram, distinguished by subscripts: roadway branch e i Branch number m i The starting node v corresponding to the roadway branch i The final node v corresponding to the roadway branch j Node number n i Roadway frictional resistance r i Air volume q in the alley i Roadway friction resistance h i Roadway weight W (e) i ), weight W (v) of the starting node of the roadway i ), weight W(v) of the end node of the roadway j ); the aforementioned tunnel branch e i Includes virtual branches, the starting node v corresponding to the roadway branch i Includes virtual nodes, the end node v corresponding to the roadway branch. j Includes virtual nodes; Step two: The negative value of the roadway friction resistance is used as the roadway weight to calculate the maximum resistance path of the mine ventilation system. The roadway friction resistance of each roadway is calculated according to formula (1). （1） Among them, h i For the roadway friction resistance, Pa;r i For the frictional resistance of the tunnel, N·S 2 / m 8 ;q i For the air volume passing through the tunnel, m 3 / s, converting the calculated result of the roadway friction resistance into a negative value, and using this as the roadway weight W(e i To calculate the minimum path weight for each lane in the topology graph; Step 3: Initialize the node weight parameters. Select the starting and ending nodes of the topology graph and initialize the node weights from the starting node to each node. When the ventilation system has multiple intake or return air shafts, additional virtual nodes need to be added. These virtual nodes transform the graph topology from a multi-source, multi-sink network to a single-source, single-sink network for path calculation. Virtual nodes connect the virtual nodes to the various intake or return air shafts, forming lines that do not actually exist in the single-source, single-sink network. The starting node is the beginning node of the intake air shaft branch in the mine. If multiple intake air shafts exist, the added virtual node is selected as the starting node. The ending node is the end node of the return air shaft branch in the mine. If multiple return air shafts exist, virtual nodes are added to assist in the calculation. When selecting the ending node, the end node of the branch with the return air shaft is selected sequentially. The initial node weight of the starting node is 0, and the weights of all other nodes are +. ; Step 4: Calculate the weights from the starting node to each node. Based on the roadway weights, calculate the weights from the selected starting node to each node in the graph sequentially. Use the absolute value of the weights from the starting node to the final node as the maximum path resistance value. The order in which the branch numbers from the starting node to the final node are updated with roadway weights is used as the maximum resistance path. Select each branch sequentially according to the branch numbering order in Step 1. Based on the roadway weights, calculate the node weights from the selected starting node to each node in the topology graph sequentially. First, calculate the weight W(v) of the current starting node. i ) and roadway weight W (e i Perform a summation operation; then sum the summation with the weight W(v) of the last node of the current branch. j Compare the result with W(v). i )+W(e i The weight W(v) of the last node is less than the weight of the last node. j Let the weight of the last node be W(v). j ) = W(v i )+W(e i Conversely, there is no need to update the weight of the last node. The next edge is continuously selected to repeat the above process of summation and comparison, and the branch number of the node weight correction with the lane weight is recorded in turn until all branches have performed relaxation calculation on the nodes, and the weight of all nodes in the graph is recalculated, judged and updated. The above step four is repeated n-1 times, where n is the number of nodes in the graph, and finally the weight of each node in the topological relationship graph from the starting node is obtained. Step 5: Check the existence of a one-way loop in the diagram. If a one-way loop exists, further processing is required; otherwise, the final result can be output.
2. The method for calculating the maximum resistance path of a mine ventilation system according to claim 1, characterized in that: In step five, if the calculation result remains unchanged, it indicates that there is no one-way loop in the graph. The maximum path resistance value and the maximum resistance path are then output. Conversely, under the existing conditions, the existence of one-way loops in the graph causes the calculation result to fall into a local loop. The node weights are affected by the continuous superposition of local roadway weights, which ultimately leads to errors in the result. Corresponding changes need to be made and the calculation needs to be recalculated.
3. The method for calculating the maximum resistance path of a mine ventilation system according to claim 2, characterized in that... The calculation method also includes step six: if a one-way loop exists, find the branch that causes the one-way loop in the topology graph, delete the branch that causes the one-way loop and connects the last node of the branch, and then re-enter step four for calculation.