CN112836334B - Reliability evaluation and post-disaster recovery method for marine network - Google Patents

Abstract

The invention discloses a method for evaluating reliability of a marine network and recovering after disaster, which comprises the following steps: collecting container shipping data, and constructing a container shipping network database so as to construct a container shipping network model; calculating a shipping network structure toughness index based on a toughness triangle theory according to a container shipping network model, constructing a shipping operation loss cost model based on a ship operation process, and constructing a toughness-cost model according to the shipping network structure toughness index and the operation loss cost; based on the toughness-cost model, the toughness-cost ratios under different recovery strategies are calculated, and the recovery strategy corresponding to the maximum toughness-cost ratio is adopted to recover the post-disaster shipping network. The method structurally evaluates the toughness index of the shipping network, constructs an operation loss cost model from the operation angle, researches the relationship between the toughness index of the shipping network and the operation loss cost, provides reference for the operation management of the marine silk road shipping network, and provides a strategy for the recovery of the marine network after the disaster.

Description

Maritime Network Reliability Assessment and Disaster Recovery Methods

technical field

The invention belongs to the technical field of marine networks, and in particular relates to a method for reliability assessment and post-disaster recovery of marine networks.

Background technique

The shipping network of the Maritime Silk Road bears more and more important economic and trade activities, but also faces many potential risks and threats. How to improve the response speed of the shipping network to major disaster events and strengthen the self-healing ability of the shipping network to make the shipping network more reliable, and how to solve the problem of post-disaster recovery of the shipping network on the Maritime Silk Road, are the relevant managers and decision makers need to pay close attention to issue.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for reliability assessment and post-disaster recovery of maritime transport networks, which solves the problems of reliability assessment of maritime transport networks and post-disaster recovery of maritime transport networks.

The present invention provides a method for reliability assessment and post-disaster recovery of shipping network, comprising the following steps:

S1. Collect container shipping data, including departure port, port of call and destination port, and build a container shipping network database;

S2. Based on the container shipping network database, with ports as nodes and routes as edges, build a container shipping network model;

S3. Calculate the structural resilience index of the shipping network based on the resilience triangle theory according to the container shipping network model, construct a shipping operation loss cost model based on the ship operation process, and construct a resilience-cost model based on the shipping network structural resilience index and operating loss cost;

S4. Based on the resilience-cost model, calculate the resilience-cost ratio under different recovery strategies, and adopt the recovery strategy corresponding to the maximum resilience-cost ratio to restore the shipping network after the disaster.

Further, the calculation formula of the toughness index _Re is:

In the formula, t ₀ represents the initial recovery time of the shipping network, t _l represents the recovery time of the shipping network, E _f represents the global network efficiency of the shipping network, and E _f0 represents the global network efficiency of the initial shipping network.

Further, the expression of the shipping operation loss cost model is:

In the formula, C represents the total loss cost, C _i represents the daily loss of operating expenses of the port, Ti represents the recovery time of the port, and _n represents the total number of ports.

Further, the resilience-cost model expression is:

In the formula, λ is the toughness-to-cost ratio, _Re is the toughness index, and C is the total loss cost.

Further, the daily loss of operating expenses of a port is the sum of port charges, security charges, pilotage charges and berthing charges.

Further, the recovery strategy includes a random recovery strategy, which randomly selects ports from the shipping network to restore the shipping network after the disaster.

Further, the recovery strategy includes a recovery strategy based on degree centrality, and the post-disaster shipping network is restored in the order of the degree centrality ranking of ports.

Further, the recovery strategy includes a recovery strategy based on proximity centrality, and the post-disaster shipping network is restored in the order of the proximity centrality ranking of ports.

Further, the recovery strategy includes a recovery strategy based on betweenness centrality, and the post-disaster shipping network is restored in the order of the betweenness centrality ranking of ports.

Further, a fully connected graph composition method is used to build a container shipping network model.

The beneficial effects of the present invention are as follows: the present invention is based on the analysis of the vulnerability and resilience of the maritime Silk Road shipping network, and combines the two stages of resilience resistance and resilience recovery according to the resilience performance curve to construct a quantitative model of the resilience index of the shipping network. Evaluate the resilience index of the shipping network, and construct an operating loss cost model from the perspective of operation, and evaluate the impact of the lost operating cost on the resilience. The research results can provide a reference for the operation and management of the shipping network of the Maritime Silk Road, and for the post-disaster recovery of the shipping network. Provide a strategy.

Description of drawings

Fig. 1 is the flow chart of the shipping network reliability assessment and post-disaster recovery method in the present invention;

Fig. 2 is the shipping network diagram of the Maritime Silk Road in the present invention;

Fig. 3 is the distribution map of ports affected by typhoons in the maritime Silk Road shipping network of the present invention;

Fig. 4 is the change of global network efficiency under two different recovery strategies in the Pacific Northwest region in the present invention;

Fig. 5 is the change of global network efficiency under two different recovery strategies in the middle and north Indian Ocean region of the present invention;

Fig. 6 is the change of global network efficiency under different recovery strategies of the shipping network in the Northwest Pacific region in the present invention;

Fig. 7 is the recovery time and resilience index of different recovery strategies of the shipping network in the Northwest Pacific region according to the present invention;

Fig. 8 is the change of global network efficiency under different recovery strategies of the shipping network in the central and northern Indian Ocean regions of the present invention;

Figure 9 shows the recovery time and resilience index of different recovery strategies of the shipping network in the central and northern Indian Ocean regions according to the present invention;

Figure 10 shows the recovery time and operating loss cost of different recovery strategies in the Pacific Northwest region in the present invention;

Figure 11 shows the recovery time and operating loss cost of different recovery strategies in the North Indian Ocean region of the present invention;

Figure 12 shows the toughness-to-cost ratio of different regions in the present invention;

FIG. 13 is a schematic diagram of calculating the structural toughness index of the shipping network based on the toughness triangle theory in the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings:

On the basis of analyzing the vulnerability and recovery capability of the maritime Silk Road shipping network, the present invention constructs a quantification model of the maritime Silk Road shipping network resilience index from the network structure level, and establishes a shipping network operation loss cost model from the economic benefit level. This paper further studies the relationship between the shipping network resilience index and shipping operation loss cost, and proposes a method to evaluate the reliability of shipping network, so as to more comprehensively reflect the status of each port in the shipping network and provide support for post-disaster recovery.

The shipping network reliability assessment and post-disaster recovery method according to the embodiment of the present invention, as shown in FIG. 1 , includes the following steps:

S1. Collect container shipping data, including departure port, port of call and destination port, and build a container shipping network database. Data can be collected from various government agency websites, gazettes, yearbooks and related websites to build a container shipping network database.

S2. Based on the container shipping network database, with ports as nodes and routes as edges, build a container shipping network model. Based on the container shipping network database, build a shipping network model: where the port N represents the total number of nodes in the network, and the number of routes between ports S represents the edges in the network. , GAL) composition method, abstract the port as the node or intersection of the network, and abstract the channel or route as the edge of the network, and construct the shipping network model M(N,S).

S3. Calculate the structural resilience index of the shipping network based on the resilience triangle theory according to the container shipping network model, build a shipping operating loss cost model based on the ship operation process, and build a resilience-cost model based on the shipping network structural resilience index and operating loss cost.

覆盖面积的比值，性能指标可以用全局网络效率表示。其计算公式如下：Among them, the toughness index _Re can be expressed as the coverage area of the performance index curve Q _(t) interrupted by external factors within the recovery time t _l and the uninterrupted curve

The ratio of the coverage area, the performance index can be expressed by the global network efficiency. Its calculation formula is as follows:

In the formula, t ₀ represents the initial recovery time of the shipping network, t _l represents the recovery time of the shipping network, E _f represents the global network efficiency of the shipping network, and E _f0 represents the global network efficiency of the initial shipping network.

The global network efficiency E _f reflects the connectivity between network nodes and the overall efficiency of the network. The higher the global network efficiency of the shipping network, the higher the benefits of container transportation. Its calculation formula is as follows:

In the formula, ε _ij represents the reciprocal of the shortest path between any two nodes i and j in the network.

T is the recovery time of the shipping network, which is inversely proportional to the gross domestic product G, and proportional to the length of the wharf shoreline L. The calculation formula is as follows:

The annual container throughput of the port is M _i , and the annual throughput is converted into the number of container ships F _i passing through the port per day, and its calculation formula is as follows:

In the formula, 4800 is the cargo load of the fifth type of ship, the unit is TEU; 365 is the total number of days in a year.

基础设施保安费

如下所示。假设每艘船的货物装载量为4800TEU，每箱重12吨，则每艘船净载货57600吨，每日引航费

的计算公式如下所示。每艘船每日的停泊费为0.25元/吨，则引航费

的计算公式如下所示。Assuming that the number of container ships imported and exported every day is equal, both of which are F _i /2, then the daily port fee

Infrastructure Security Fee

As follows. Assuming that the cargo loading capacity of each ship is 4800TEU and each box weighs 12 tons, the net cargo load per ship is 57600 tons, and the daily pilotage fee

The calculation formula is as follows. The daily berthing fee for each ship is 0.25 yuan / ton, the pilotage fee

The calculation formula is as follows.

安保费

引航费

和停泊费

之和，那么港口每日损失的运营费用C_i和总的损失成本C计算公式如下所示：Through sorting, the daily loss of operating expenses of the port is port charges

Security costs

Pilotage fee

and parking fees

The sum of the operating expenses C _i and the total loss cost C for the daily loss of the port is as follows:

In the formula, C represents the total loss cost, C _i represents the daily loss of operating expenses of the port, Ti represents the recovery time of the port, and _n represents the total number of ports.

Finally, the toughness-to-cost ratio λ of the shipping network resilience of the Maritime Silk Road represents the impact of the performance loss and cost loss of the shipping network on the resilience, and its calculation formula is as follows:

In the formula, C reflects the restoration cost of the shipping network, and _Re is the resilience index.

S4. Based on the resilience-cost model, calculate the resilience-cost ratio under different recovery strategies, and adopt the recovery strategy corresponding to the maximum resilience-cost ratio to restore the shipping network after the disaster.

Next, take the shipping network of the Pacific Northwest and the North Indian Ocean of the Maritime Silk Road under the influence of storms as an example, as shown in Figure 3, to conduct a specific analysis. The specific steps are:

(1) Build a container shipping schedule database

The container shipping network is composed of route networks and network nodes. The maritime Silk Road shipping network database should maintain the accuracy of routes and data, which can be obtained from the official website hosted by the National Information Center and the official documents released by the French well-known shipping analysis agency Alphaliner. Global liner shipping service information, collect port and route information of 37 countries along the Maritime Silk Road, including basic information such as departure port, destination port, port of call, timetable, and fleet, and build the database of this embodiment based on the above information.

(2) Building a container shipping network model of the Maritime Silk Road

The statistics of container shipping service data of 19 liner companies from the end of October 2016 to the end of December 2016 were carried out, and 1,249 shipping routes (passing through 37 countries and 254 ports) related to the Maritime Silk Road were screened out. According to the above information, take the port as the node and the route as the edge to build the maritime Silk Road shipping network, as shown in Figure 2.

(3) Analysis of network centrality

① Degree centrality refers to the number of other nodes connected to a node, representing the relevance and importance of the node to other nodes. If the degree value of a point is larger, it means that this node is more closely connected with other nodes. The calculation formula of the degree value is as follows, where n represents the total number of nodes in the network, and δ _ij represents the number of edges between port nodes i and j.

As shown in Table 1, the maximum degree of the node is 273. This port is Hong Kong, China, indicating that the port connected to Hong Kong, China has the most ports. The top five ports in terms of degree centrality are Hong Kong Port, Singapore Port, Shanghai Port, Ningbo Port, and Yantian Port, indicating that there are a large number of routes connected to these ports, and they occupy a higher position in the maritime Silk Road shipping network. Among them, the port with the highest out-degree is Ningbo Port, but its in-degree is only 26. The large difference between the out-degree and the in-degree indicates that the port’s route connection is unbalanced, and the trade demand is different from the direction of cargo flow.

② Proximity centrality represents the sum of the shortest distances from all nodes to a fixed node, which is used to evaluate the spatial advantage of a point in the network and the efficiency of communication with other nodes. If the distances from other nodes to a fixed node are very small, the closeness centrality of the fixed node is high. The calculation of closeness centrality is as follows, where d _ij represents the shortest distance between two nodes, and n represents the number of ports.

The ports that are close to the centrality mainly include Hong Kong Port, Singapore Port, Yantian Port, Shanghai Port, and Ningbo Port, which are all important hub ports on the Maritime Silk Road. In general, the values close to the centrality of each port are not very different, and each port in the network has a good spatial advantage in the Maritime Silk Road.

③ Betweenness centrality measures the degree to which a node is located in the "middle" of other "point pairs" in the graph, reflecting the mediating role of the node in the network. In the following formula, s, t represent a set of node pairs, δ(s, t|i) is the number of times that the shortest distance of a node pair passes through node i, and δ(s, t) is the total number of shortest paths between node pairs.

The Port of Singapore is the port with the highest intermediary centrality, which reflects its position as a transportation fortress in the shipping network and has a strong cargo transfer capacity. Singapore Port, Hong Kong Port, Port Klang, Busan Port and Yantian Port are the top five ports in betweenness centrality, and there are 59 ports in the network whose betweenness centrality value is 0, indicating that the ports between the Maritime Silk Road regions There are huge differences in intermediary capacity and uneven development of shipping networks. See Table 1 for the top 10 ports in each centrality of the Maritime Silk Road shipping network.

Table 1 The top 10 ports of the Maritime Silk Road shipping network by centrality

(4) Vulnerability and resilience of regional networks

According to the methods of vulnerability analysis and resilience analysis, global network efficiency is selected as the performance index for evaluating vulnerability and resilience, and the vulnerability and resilience of different regional networks under storm disasters are studied.

①Northwest Pacific region

The initial efficiency of the shipping network in the Pacific Northwest was 37.67%, and the global network efficiency of the shipping network destroyed by storm damage was 18.35%. In order to better describe the degree of network degradation, the relative values shown in Figure 4 are used to reflect the percentage change in network efficiency. After the storm disaster, the network efficiency in the Pacific Northwest decreased by 51.29% compared with the initial state, and the global network efficiency under the recovery strategy based on degree centrality, near centrality and betweenness centrality was higher than that under the recovery strategy based on the random recovery strategy. faster.

②North Indian Ocean region

The stochastic recovery strategy and the recovery strategy based on degree centrality, near centrality, and betweenness centrality were used to analyze the vulnerability and resilience of the shipping network in the North Indian Ocean before and after the disaster. The results are shown in Figure 5. The initial efficiency of the shipping network is 37.67%, and the global network efficiency after storm damage is 29.24%. Compared with the initial state before the disaster, the network efficiency of the shipping network decreased by 22.38% after the disaster. Similarly, the overall network efficiency rises faster when the shipping network recovers based on a certain recovery strategy.

The results of the study show that the network efficiency of the shipping network decreases more significantly in the Pacific Northwest region than in the North Indian Ocean region, indicating that the Pacific Northwest region is more vulnerable. The shipping network in these two regions adopts a specific recovery strategy to restore the network than the random recovery strategy, and the overall network efficiency rises faster, which means that with certain recovery measures, the shipping network will reach its original state faster and better. .

(5) The resilience index of each regional network based on different recovery strategies

Based on the analysis results of the shipping network vulnerability and resilience of the Northwest Pacific region and the North Indian Ocean region in the previous section, the resilience indices of these two regions are calculated according to the resilience index quantitative model.

①Northwest Pacific region

The GDP data in 2018 of 8 countries in the Northwest Pacific region, China, Indonesia, Malaysia, Vietnam, the Philippines, Thailand, South Korea and Japan, and the length of the wharf shorelines of 47 ports can be calculated, and the recovery time of each port can be calculated. Since the units of the GDP value and the length of the wharf shoreline are not uniform, they need to be normalized before calculation. Considering the diversity and suddenness of disasters and the unequal distribution of resources in each port, the present invention introduces an adjustment coefficient k to reflect the differences in port post-disaster reconstruction policies and effects of different port management departments. The recovery time of Tokyo Port from the 2011 earthquake was 30 days through literature review, and the present invention will take this as a reference and set up adjustment coefficients to make the recovery time of each port consistent with the actual situation. The value of k is related to factors such as the completeness of the port's infrastructure, the amount of material storage required for restoration, the division of labor, and the level of restoration technology. The GDP data of the port, the length of the shoreline of the terminal and the recovery time of each port are shown in Table 2 below.

Table 2. Gross National Product, Dock Shoreline Length and Recovery Days for Ports in the Pacific Northwest Region

According to the invention, the port repairs are carried out at intervals of 20% of the number of ports, and the repair time is based on the longest repair time in each repair stage, and the resilience index of the shipping network in the Northwest Pacific is obtained.

As shown in Figure 6 and Figure 7, after calculation, it can be seen that the area enclosed by the initial efficiency curve and the time axis of the shipping network based on the random recovery strategy is 280.6415, and the area enclosed by the resilience performance curve and the time axis is 200.0023, indicating that the storm disaster The resilience index of the shipping network in the Lower Northwest Pacific region based on the stochastic recovery strategy was 0.7127, and the recovery time was 745 days. The area enclosed by the initial efficiency curve and the time axis of the shipping network based on the degree centrality recovery strategy is 261.4298, and the area enclosed by the resilience performance curve and the time axis is 188.6830. It can be seen that the shipping network in the Northwest Pacific region under the storm disaster is based on degree centrality. The resilience index of recovery strategy recovery was 0.7217, and the recovery time was 694 days. The area enclosed by the initial efficiency curve and the time axis of the shipping network based on the near centrality recovery strategy is 261.4298, and the area enclosed by the resilience performance curve and the time axis is 189.6062. It can be seen that the shipping network in the Northwest Pacific region under the storm disaster is based on the near centrality The resilience index of recovery strategy recovery was 0.7253, and the recovery time was 694 days. The area enclosed by the initial efficiency curve and the time axis of the shipping network based on the betweenness centrality recovery strategy is 244.4783, and the area enclosed by the resilience performance curve and the time axis is 174.5658. It can be seen that the shipping network in the Northwest Pacific region under the storm disaster is based on betweenness centrality The resilience index of recovery strategy recovery was 0.7140, and the recovery time was 649 days.

When the shipping network in the Northwest Pacific region chooses to recover based on the near-centrality recovery strategy, the resilience index is the largest of 0.7253, which is 1.77% lower than that based on the random recovery strategy, indicating that the resilience loss is the smallest and the performance recovery is better. The recovery time of shipping network based on betweenness centrality in this region is 96 days shorter than that based on random recovery strategy. When the two indicators of shipping network performance recovery and time recovery are comprehensively considered, the recovery strategy based on betweenness centrality is better. .

②North Indian Ocean region

The gross domestic product (GDP) of 6 countries in the Indian Ocean region and the length of the wharf shoreline of 27 ports are collected. According to the actual recovery days of Tokyo Port in the earthquake, the adjustment coefficient k is set to obtain the recovery time of each port. Finally, the global network efficiency changes of the shipping network under the random recovery strategy, degree centrality-based, near centrality, and betweenness centrality recovery strategies are shown in Figure 8.

As shown in Figure 8 and Figure 9, the area enclosed by the initial efficiency curve and the time axis of the shipping network based on the stochastic recovery strategy is 80.2371, and the area enclosed by the resilience performance curve and the time axis is 68.6154. The resilience index of shipping network recovery based on stochastic recovery strategy was 0.8552, and the recovery time was 213 days. The area enclosed by the initial efficiency curve and the time axis of the shipping network based on the degree centrality recovery strategy is 62.1555, and the area enclosed by the resilience performance curve and the time axis is 53.7469. It can be seen that the shipping network in the northwest Indian Ocean region under the storm disaster is based on degree centrality. The resilience index of recovery strategy recovery was 0.8647, and the recovery time was 165 days. The area enclosed by the initial efficiency curve and the time axis of the shipping network based on the near-centrality recovery strategy is 71.1963, and the area enclosed by the resilience performance curve and the time axis is 62.3180. It can be seen that the shipping network in the North Indian Ocean region has recovered based on the near-centrality recovery strategy. The resilience index was 0.8753 and the recovery time was 189 days. The area enclosed by the initial efficiency curve and the time axis of the shipping network based on the betweenness centrality recovery strategy is 74.2099, and the area enclosed by the resilience performance curve and the time axis is 65.6383. It can be seen that the shipping network in the North Indian Ocean has recovered based on the betweenness centrality recovery strategy. The resilience index was 0.8845 and the recovery time was 197 days.

Through comparison and analysis, the shipping network in the Northwest Pacific region has a smaller resilience index and a longer recovery time than the shipping network in the North Indian Ocean region. The research results of the two regions both show that adopting certain recovery strategies can not only shorten the recovery time of the shipping network, but also effectively reduce the resilience loss of the shipping network and improve the recovery efficiency of the shipping network performance. However, in different regions, the recovery measures taken to reduce the loss of resilience are different. The recovery strategies of the shipping network in the Northwest Pacific region and the North Indian Ocean region are the recovery strategy based on proximity centrality and the recovery strategy based on betweenness centrality. When considering the two indicators of resilience loss and recovery time at the same time, the recovery strategy based on betweenness centrality is better for the shipping networks in the two regions.

(6) Loss of operation cost of each regional network

According to the loss operation cost model, the loss operation cost of the Northwest Pacific region and the North Indian Ocean region under the influence of storm disaster is analyzed.

①Northwest Pacific region

Table 3 presents container throughput and lost operating costs for ports in the Pacific Northwest, as follows:

Table 3 Container throughput and lost operating costs of ports in the Pacific Northwest

According to the recovery strategy of the port, it is assumed that in the process of restoring the port according to the proportion, the recovery time is based on the maximum port recovery time of each recovery stage. When calculating the operating cost of the port loss in each stage, the total time required should be the sum of the time the port in the area was repaired and the time waiting for the completion of the repair in the previous stages. As shown in Figure 10, the total recovery time of the shipping network based on the random recovery strategy is 745 days, and the lost operating cost is 18.098 billion yuan. The total recovery time based on the degree-centric recovery strategy was 694 days, and the lost operating cost was 14.761 billion yuan. The total recovery time of the shipping network based on the near-centrality recovery strategy was 694 days, and the lost operating cost was 13.461 billion yuan. The total recovery time of the shipping network based on the intermediary centrality recovery strategy is 649 days, and the lost operating cost is 17.006 billion yuan.

Through comparison and analysis, the shipping network in the Northwest Pacific region chooses to recover based on the near-centrality recovery strategy. The loss and operating cost of the shipping network is at least 13.461 billion yuan, which is 4.637 billion yuan less than the recovery based on the random strategy, and the economic benefit is the highest. Recovery based on betweenness centrality recovery strategy took the shortest time at 649 days. When the two indicators of recovery time and recovery cost are comprehensively considered, the recovery strategy based on the near centrality recovery strategy is the best.

②North Indian Ocean region

Table 4 shows the container throughput and lost operating costs of ports in the North Indian Ocean region, as follows:

Table 4 Container throughput and lost operating costs of ports in the North Indian Ocean region

As shown in Figure 11, the total recovery time of the shipping network based on the random recovery strategy is 213 days, and its operating loss cost is 685 million yuan. The total recovery time of the shipping network based on the degree centrality recovery strategy is 165 days, and its operating loss cost is 647 million yuan. The total recovery time of the shipping network based on the near-centrality recovery strategy was 189 days, and its operational loss cost was 691 million yuan. The total recovery time based on the betweenness centrality recovery strategy is 197 days, and its operating loss cost is 676 million yuan.

Through comparison and analysis, storm disasters caused more economic losses to the shipping network in the Northwest Pacific than in the North Indian Ocean. The study found that repairing ports in the Pacific Northwest and North Indian Ocean regions based on different types of recovery strategies can not only shorten the recovery time of the shipping network, but also reduce the cost of lost operations and save the funds needed to repair ports after disasters. This means that adopting specific repair strategies can not only effectively promote the recovery efficiency of the shipping network, but also reduce the economic losses caused by disasters. However, the measures taken to reduce economic losses are different in different regions. The shipping network in the Northwest Pacific region adopts the recovery strategy based on proximity centrality, which is more effective, while the shipping network in the North Indian Ocean region adopts the recovery strategy based on degree centrality.

(7) Comprehensive analysis of "Silk Road" network storm resilience-cost under different recovery strategies

Based on the resilience-cost model, a comprehensive analysis of the resilience-cost of shipping networks in the Pacific Northwest and North Indian Ocean regions under storm disasters

①Northwest Pacific region

Table 5 Resilience-to-cost ratios in the Pacific Northwest Region

As shown in Table 5, the shipping network in the Pacific Northwest region has the shortest recovery time and the fastest recovery rate based on the intermediary centrality recovery strategy, which is 649 days. This means that when faced with the need to minimize port repair time and reduce ship schedule delays, a recovery strategy based on intermediary centrality can be adopted to maintain ports, that is, to prioritize the repair of ports with high intermediary centrality. Based on the near-centrality recovery strategy, the resilience index is the largest, the loss of operating costs is the least, and the toughness-to-cost ratio is the largest at 0.00540. This shows that in the Pacific Northwest region, choosing port restoration based on a near-centrality recovery strategy results in the least loss of resilience of the shipping network and the least economic loss. Although the implementation of this strategy increases the recovery time, it can achieve higher economic benefits.

②North Indian Ocean region

Table 6 Toughness-to-cost ratios in the North Indian Ocean region

According to Table 5, Table 6 and Figure 12, the toughness-to-fee ratios of ports in different regions are compared and analyzed. The toughness-to-cost ratio of the shipping network in the Northwest Pacific region is much smaller than that of the North Indian Ocean region, which indicates that the impact of the storm on the Northwest Pacific region is much higher than that in the Indian Ocean region. After a disaster, more time and money will need to be devoted to recovery in the Pacific Northwest. The shipping networks in the two regions are recovered by adopting a random recovery strategy, with the lowest toughness-to-cost ratio. The toughness-to-cost ratios of the shipping network in the Pacific Northwest are ranked from high to low, and the recovery strategy based on proximity centrality is the best, followed by the recovery strategy based on degree centrality, then the recovery strategy based on betweenness centrality, and finally the random recovery strategy. The toughness-to-cost ratio of the shipping network in the North Indian Ocean is ranked from high to low as the recovery strategy based on degree centrality, the recovery strategy based on betweenness centrality, and the recovery strategy based on proximity centrality. This also shows that ports with a high ranking of close centrality in the Northwest Pacific region have a greater impact on structural resilience and economic benefits, such as Singapore Port, Hong Kong Port, and Shenzhen Port. Ports with high regional centrality ranking in the North Indian Ocean have a greater impact on structural resilience and economic benefits, such as Nawasiva Port, Laem Chabang Port and Jeddah Port. These ports need to be restored first to ensure the smooth flow of related routes.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be Included in the protection scope of the present invention.

Claims (10)

1. A shipping network reliability assessment and post-disaster recovery method, characterized in that, comprise the following steps: S1. Collect container shipping data, including departure port, port of call and destination port, and build a container shipping network database; S2. Based on the container shipping network database, with ports as nodes and routes as edges, build a container shipping network model; S3. Calculate the structural resilience index of the shipping network based on the resilience triangle theory according to the container shipping network model, construct a shipping operation loss cost model based on the ship operation process, and construct a resilience-cost model based on the shipping network structural resilience index and operating loss cost; S4. Based on the resilience-cost model, calculate the resilience-cost ratio under different recovery strategies, and adopt the recovery strategy corresponding to the maximum resilience-cost ratio to restore the shipping network after the disaster. 2. The shipping network reliability assessment and post-disaster recovery method according to claim 1, wherein the calculation formula of the resilience index _Re is:

In the formula, t ₀ represents the initial recovery time of the shipping network, t _l represents the recovery time of the shipping network, E _f represents the global network efficiency of the shipping network, and E _f0 represents the global network efficiency of the initial shipping network. 3. The shipping network reliability assessment and post-disaster recovery method according to claim 2, wherein the expression of the shipping operation loss cost model is:

In the formula, C represents the total loss cost, C _i represents the daily loss of operating expenses of the port, Ti represents the recovery time of the port, and _n represents the total number of ports. 4. The shipping network reliability assessment and post-disaster recovery method according to claim 3, wherein the resilience-cost model expression is:

In the formula, λ is the toughness-to-cost ratio, _Re is the toughness index, and C is the total loss cost. 5. The shipping network reliability assessment and post-disaster recovery method according to claim 3, characterized in that, the operating cost of the daily loss of the port is the sum of port charges, security charges, pilotage charges and berthing charges. 6 . The shipping network reliability assessment and post-disaster recovery method according to claim 1 , wherein the recovery strategy includes a random recovery strategy, randomly selecting ports from the shipping network, and restoring the shipping network after the disaster. 7 . 7. The shipping network reliability assessment and post-disaster recovery method according to claim 1, wherein the recovery strategy comprises a degree-centrality-based recovery strategy, and the post-disaster shipping network is carried out in the order of the degree-centrality ranking of ports. recover. 8. The shipping network reliability assessment and post-disaster recovery method according to claim 1, wherein the recovery strategy includes a recovery strategy based on proximity centrality, and the post-disaster shipping network is carried out in the order of proximity centrality ranking of ports. recover. 9. The shipping network reliability assessment and post-disaster recovery method according to claim 1, wherein the recovery strategy includes a recovery strategy based on betweenness centrality, and takes the betweenness centrality ranking of the port as an order to carry out the post-disaster shipping network. recover. 10 . The shipping network reliability assessment and post-disaster recovery method according to claim 1 , wherein the container shipping network model is constructed using a fully connected graph composition method. 11 .

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