A ship channel assessment method based on network flow

Abstract

The present invention discloses a ship channel evaluation method based on network flow, comprising the following steps: 1) according to the design of the ship channel to be evaluated, a ship channel network with all ship cabins or personnel circulation stations as nodes is constructed; 2) for the constructed channel network, the flow of people in each arc is used as the design variable, the continuity equation of energy conservation followed by each node and the capacity limit satisfied by each arc are used as constraints, and the total distance of network travel is minimized as the optimization goal, and a network flow optimization model is established; 3) the model is solved by the branch and bound method to obtain the flow of each arc; 4) the network flow when a node or arc in the network is damaged is calculated, and the maximum flow of the corresponding arc is set to 0 for simulation, and the evaluation result is obtained. The method of the present invention can provide a basis for the design, evaluation, verification and improvement of the channel network.

Description

Technical Field

[0001] The invention relates to a ship channel design technology, and in particular to a ship channel evaluation method based on network flow. Background Art

[0002] The design of ship passages is one of the important tasks of the ship's general layout design. The passages directly affect the rationality of the design of personnel flow, logistics and damage control. The design of passage layout should facilitate various activities such as combat operations, personnel circulation, goods transportation and equipment handling; the circulation route should be as short, straight and smooth as possible, and ensure that all cabins and parts are accessible, which involves the design and verification of the passages. Good passage design can not only improve the efficiency of ship personnel and logistics, but also help the emergency circulation of personnel under damage control conditions, so that the ship can restore its combat effectiveness and vitality as soon as possible. There are many cabins, personnel and departments on the ship, and the deployment and scheduling of personnel under various conditions are complicated. When the ship is attacked, the passage may be damaged and impassable. In response to such problems, it is necessary to provide a flow evaluation method under the complete working condition and damage working condition of the ship passage network to provide a basis for the design, evaluation, verification and improvement of the ship passage network. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a ship channel assessment method based on network flow in view of the defects in the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a ship channel assessment method based on network flow, comprising the following steps:

[0005] 1) According to the ship channel design to be evaluated, a ship channel network with cabins or personnel circulation stations as nodes is constructed, wherein the ship channel network includes nodes representing cabins or stations and arcs representing channels connecting nodes; the direction of the arc is set: including forward flow, reverse flow and bidirectional flow; the maximum flow rate accommodated by the channels corresponding to all arcs is set;

[0006] 2) For the constructed channel network, the flow of people in each arc is taken as the design variable, the continuity equation of energy conservation of each node and the capacity limit of each arc are taken as constraints, and the minimum total distance of network travel is taken as the optimization goal to establish a network flow optimization model;

[0007] Min∑ (i，j)∈E c ij x ij ········(i,j)∈E··············

[0008] St. ij ≤u ij ············(i,j)∈E

[0009] x ij ≥0·············(i,j)∈E

[0010] ∑ (j，i)∈E x ji -∑ (i，j)∈E x ij =b i ·····(i,j)∈E·i∈N··

[0011] Where N is the set of all nodes, E is the set of all arcs, and both N and E are integer sets;

[0012] x ij is the flow of people on the arc between node i and node j;

[0013] c ij is the length of the arc between node i and node j, that is, the distance of the channel;

[0014] u ij is the maximum flow of the arc between node i and node j;

[0015] b i is the supply / demand of node i, which is the difference between the outflow and inflow of the node;

[0016] 3) Use the branch and bound method to solve the model and obtain the flow rate x of each arc ij ;

[0017] The entire solution space of a constrained optimization problem (whose feasible solutions are finite in number) is systematically searched appropriately. The entire solution space is usually repeatedly divided into smaller and smaller subsets, which is called branching; and a target lower bound is calculated for the solution set in each subset (for the minimum problem), which is called bounding. After each branch, if the target value of a known feasible solution set cannot reach the current limit, this subset is discarded. In this way, many subsets are not considered, which is called pruning. The idea is specific: there is a maximization integer programming problem A, and its corresponding linear programming problem is B. Starting from solving problem B, if its optimal solution does not meet the integer condition of A, then the optimal objective function of B must be the upper bound of the optimal objective function z* of A, denoted by z - ; The objective function value of any feasible solution of z will be a lower bound z_ of z. The branch and bound method is a method of dividing the feasible region of B into subregions. Gradually reduce z - and increase z_. Finally, z* is obtained.

[0018] 4) Calculate the network flow when a node or arc in the network is damaged (i.e., N-1 condition), and perform simulation calculations by setting the maximum flow of the corresponding arcs to 0 in turn to obtain the evaluation results.

[0019] The channel design is verified and improved through the evaluation results, such as whether it meets the survivability design requirements of the NX damage condition, whether there are redundant channels that can be deleted, etc. The capacity of the channel can be designed with reference to the calculation results to reduce the travel distance and overall resources.

[0020] The beneficial effects of the present invention are as follows: the method of the present invention can provide a basis for the design, evaluation, verification and improvement of the channel network, and has a reference significance for the design rationality, recoverable vitality evaluation and damage control decision-making and operation of the channel network. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0022] Figure 1 is a simplified channel network node distribution diagram of an embodiment of the present invention;

[0023] Figure 2 is a complete channel network flow diagram of an embodiment of the present invention;

[0024] Figure 3 is a channel network N-arc 4 flow diagram of an embodiment of the present invention;

[0025] Figure 4 is a flow diagram of a channel network N-arc 7 according to an embodiment of the present invention;

[0026] Figure 5 is a flow diagram of a channel network N-arc 14 according to an embodiment of the present invention;

[0027] Figure 6 is a flow diagram of a channel network N-arc 25 according to an embodiment of the present invention;

[0028] Figure 7 is the maximum network flow of the channel network N-1 working condition of the embodiment of the present invention;

[0029] Figure 8 It is a method flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] like Figure 8 As shown, a ship channel assessment method based on network flow includes the following steps:

[0032] 1) According to the ship channel design to be evaluated, a ship channel network with cabins or personnel circulation stations as nodes is constructed, wherein the ship channel network includes nodes representing cabins or stations and arcs representing channels connecting nodes; the direction of the arc is set: including forward flow, reverse flow and bidirectional flow; the maximum flow rate accommodated by the channels corresponding to all arcs is set;

[0033] 2) For the constructed channel network, the flow of people in each arc is taken as the design variable, the continuity equation of energy conservation of each node and the capacity limit of each arc are taken as constraints, and the minimum total distance of network travel is taken as the optimization goal to establish a network flow optimization model;

[0034] Min∑ (i，j)∈E c ij x ij ········(i,j)∈E··············

[0035] St. ij ≤u ij ···········(i,j)∈E

[0036] x ij ≥0·············(i,j))∈E

[0037] ∑ (j，i)∈E x ji -∑ (i，j)∈E x ij =b i ·····(i,j)∈E·i∈N·

[0038] Where N is the set of all nodes, E is the set of all arcs, and both N and E are integer sets;

[0039] X ij is the flow of people on the arc between node i and node j;

[0040] c ij is the length of the arc between node i and node j, that is, the distance of the channel;

[0041] u ij is the maximum flow of the arc between node i and node j;

[0042] b i is the supply / demand of node i, which is the difference between the outflow and inflow of the node;

[0043] 3) Use the branch and bound method to solve the model and obtain the flow rate x of each arc ij ;

[0044] The entire solution space of a constrained optimization problem (whose feasible solutions are finite in number) is systematically searched appropriately. The entire solution space is usually repeatedly divided into smaller and smaller subsets, which is called branching; and a target lower bound is calculated for the solution set in each subset (for the minimum problem), which is called bounding. After each branch, if the target value of a known feasible solution set cannot reach the current limit, this subset is discarded. In this way, many subsets are not considered, which is called pruning. The idea is specific: there is a maximization integer programming problem A, and its corresponding linear programming problem is B. Starting from solving problem B, if its optimal solution does not meet the integer condition of A, then the optimal objective function of B must be the upper bound of the optimal objective function z* of A, denoted by z - ; The objective function value of any feasible solution of z will be a lower bound z_ of z. The branch and bound method is a method of dividing the feasible region of B into subregions. Gradually reduce z - and increase z_. Finally, z* is obtained.

[0045] 4) The network flow is calculated when a node or arc in the network is damaged (i.e., N-1 condition), and the evaluation results are obtained by setting the maximum flow of the corresponding arcs to 0 for simulation.

[0046] The channel design is verified and improved through the evaluation results, such as whether it meets the survivability design requirements of the NX damage condition, whether there are redundant channels that can be deleted, etc. The capacity of the channel can be designed with reference to the calculation results to reduce the travel distance and overall resources.

[0047] For example:

[0048] (1) Build a two-deck simplified channel network including various cabins and station nodes, such as Figure 1 As shown in the figure, the process of 12 soldiers going from the cabin to each station in a simulated combat deployment is shown. The simplified channel network contains 23 nodes, and the actual ship position (simplified example) and station settings of each node are shown in Table 1. The arcs connected by the nodes are shown in Table 2. The network contains 26 arcs, and the direction of the arc is 1 for forward flow, 2 for reverse flow, and 3 for bidirectional flow. The arcs of the channel network are all bidirectional flows. The maximum capacity of all arcs is initially set to 8 people.

[0049] Table 1 Channel network nodes

[0050]

[0051]

[0052] Table 2 Channel network arc list

[0053]

[0054]

[0055]

[0056]

[0057] (2) For the constructed network, solve it in MATLAB, and the calculation results are as follows Figure 2 As shown, Figure 2 The hard dashed lines represent the flow channels without flow, and the flow with flow arcs is represented by the line width.

[0058] (3) Channel vitality assessment

[0059] Table 3 lists several typical network flows (arc 4, 7, 14, 25 damage conditions). The red star line indicates the location of the damage arc, the line width indicates the flow rate of each arc, and the dotted line indicates no flow. Figures 3 to 6 shown.

[0060] Table 3 Network flows for each typical working condition

[0061]

[0062]

[0063] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A ship channel assessment method based on network flow, characterized in that: The following steps are involved: 1) According to the ship channel design to be evaluated, a ship channel network with cabins or personnel circulation stations of the whole ship as nodes is constructed, wherein the ship channel network comprises nodes representing cabins or personnel circulation stations and arcs representing channels connecting the nodes; Set the direction of the arc: including forward flow, reverse flow and bidirectional flow; set the maximum flow of people that can be accommodated in the corresponding channels of all arcs; 2) For the constructed channel network, the flow of people in each arc is taken as the design variable, the continuity equation of energy conservation of each node and the capacity limit of each arc are taken as constraints, and the minimum total distance of network travel is taken as the optimization goal to establish a network flow optimization model; The established network flow optimization model is as follows: Min∑ (i，j)∈E c ij x ij (i,j)∈E St x ij ≤u ij (i,j)∈E x ij ≥0 (i,j)∈E ∑ (j，i)∈E x ji -∑ (i，j)∈E x ij =b i (i,j)∈Ei∈N Where N is the set of all nodes, E is the set of all arcs, and both N and E are integer sets; x ij is the flow of people on the arc between node i and node j; c ij is the length of the arc between node i and node j, that is, the distance of the channel; u ij is the maximum flow of the arc between node i and node j; b i is the supply / demand of node i, which is the difference between the outflow and inflow of the node; 3) Use the branch and bound method to solve the model and obtain the flow rate x of each arc ij ; 4) Calculate the network flow when a node or arc in the network is damaged, and perform simulation calculations by setting the maximum flow of the damaged arcs to 0 in turn to obtain the evaluation results.

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