Container empty container distribution optimization method and system considering multiple transportation modes

Abstract

The application provides a container empty container distribution optimization method and system considering multiple transportation modes, belongs to the technical field of logistics transportation resource allocation, and constructs a sea-railway-public multi-modal empty container distribution network; according to the constructed sea-railway-public multi-modal empty container distribution network, an integer programming model of multi-modal empty container distribution is constructed with the lowest total cost as the target; the integer programming model of multi-modal empty container distribution is solved, and the optimal empty container distribution quantity between a port and a container freight station and the empty container inventory of each container freight station in each planning period are determined. The application can fully exert the advantages of each transportation mode and meet different transportation demands; a multi-period empty container distribution model is constructed, multi-period decision can be made, the empty container distribution quantity on each transportation line, the rented empty container quantity, the inventory quantity of the container freight station in each decision period and the selected transportation mode of each transportation line in each period are determined.

Description

Technical Field

[0001] This invention relates to the field of logistics and transportation resource allocation technology, specifically to an optimized method and system for empty container relocation that considers multiple modes of transportation. Background Technology

[0002] Container shipping refers to the assembly of goods into units using containers, loading and unloading operations, and transportation using rail, road, or sea. Empty containers are a crucial resource in container logistics. The issue of empty container relocation is a key problem arising during container turnover, primarily caused by trade imbalances between regions. This imbalance manifests in two main ways: First, in export-oriented regions, shippers require empty containers to pack their goods, leading to a large demand for them. If there aren't enough empty containers locally, the solution is usually to lease or relocate them from other regions. However, container leasing costs are typically high, so logistics companies prefer to relocate containers to meet the demand. Second, in import-oriented regions, arriving loaded containers become empty after unloading. Insufficient demand for empty containers in these regions often leads to an accumulation of empty containers, requiring timely relocation to avoid additional inventory costs. It's important to emphasize that approximately 20% of containers transported globally are empty. Although these empty containers occupy the same transportation space and incur the same costs as loaded containers, they do not generate any revenue. This situation is inefficient for the logistics industry, and solutions need to be sought to maximize resource utilization, reduce additional costs, and improve overall transportation efficiency.

[0003] Currently, there are many technologies related to empty container relocation, but they all have certain problems in different aspects: First, most existing technologies usually only consider a single container freight station, ignoring the complex relationships between freight stations of different types and locations. This simplification may lead to failure to formulate optimal empty container relocation plans in different scenarios; second, existing technologies are usually limited to one mode of transport, failing to fully consider the joint relocation of multiple modes of transport. This may lead to a failure to fully leverage the synergistic advantages of different modes of transport, resulting in reduced efficiency of empty container relocation plans; finally, many existing technologies fail to build multi-period models that can better adapt to the complexity of container logistics. In reality, demand and supply may change over time, thus requiring a multi-period model to handle this dynamic nature.

[0004] Traditional research on empty container relocation has mainly focused on single modes of transport. However, with the development of supply chains and container multimodal transport, researchers have realized the limitations of single modes of transport and have begun to explore combinations of multiple modes of transport for empty container relocation.

[0005] Regarding the technology of empty container relocation in a single mode of transportation, Song et al. considered the problem of empty container relocation in maritime transport involving multiple service routes, multiple vessels, and multiple scheduled routes, and proposed two optimization methods: the first is an integer programming method based on two-stage shortest path, and the second is a two-stage integer programming method based on heuristic rules. Yang Guang et al., based on an analysis of the problems in empty container relocation in railway transport, used a multi-objective programming model to establish an optimization model for empty container relocation in railway transport, aiming at minimizing transportation costs and prioritizing the relocation of major containers. Shen Erle, from the perspective of low-carbon economy, considered maritime carbon trading and carbon emission constraints, and established a dual-objective optimization model for empty container relocation in maritime transport under the premise of ensuring the normal transportation of loaded containers. Jia Qiong analyzed the causes of empty container relocation in port logistics from a qualitative perspective and put forward relevant suggestions for improving the management of empty container relocation.

[0006] Regarding the technology of empty container relocation across multiple modes of transportation, Runfangyuan et al., based on a comparison of empty container relocation problems in sea and rail transport, analyzed the nodes and processes of empty container relocation in sea-rail intermodal transport, as well as the composition of container relocation costs, and specifically analyzed the costs of container leasing and port stacking. Xie et al. studied the problem of empty container sharing and coordination in multimodal transport. By establishing centralized and decentralized models, they explored the inventory sharing and coordination problem of empty containers between seaports and land ports in container multimodal transport, and designed bilateral repurchase contracts to solve the inventory sharing game between railway companies and liner companies. Tian et al. first considered empty container relocation when land ports and seaports did not cooperate, and then established decentralized and centralized models for the case of cooperation between the two ports. They analyzed the optimal level of empty container inventory for land ports and seaports under different models, as well as the impact of empty container relocation price changes on inventory levels. Xing Lei et al. focused on the integrated sea-land container transport system between China-Europe freight trains, and considered foldable containers. They constructed a mixed-integer linear programming model with the goal of minimizing costs, and solved it using CPLEX.

[0007] In summary, the existing technologies still have shortcomings and drawbacks, including: (1) Existing empty container relocation technologies mainly focus on the relocation of a single mode of transport, while having significant limitations in considering the coordinated transport of multiple modes of transport. These technologies fail to fully explore and leverage the advantages of combined transport of multiple modes of transport, and therefore fail to provide comprehensive decision support to meet the empty container relocation needs across the entire network. (2) Most existing empty container relocation technologies only focus on the research of a single type of container freight station, without fully considering the diversity between freight stations, that is, without fully distinguishing and deeply analyzing the specific functions of various types of container freight stations.

[0008] Therefore, existing research has not yet developed more innovative and practical strategies for empty container relocation for different types of freight stations, a limitation that has a significant impact on promoting efficiency, sustainability, and economy in the container logistics sector. Summary of the Invention

[0009] The purpose of this invention is to provide a method and system for optimizing the handling of empty containers that takes into account multiple modes of transportation, so as to solve at least one of the technical problems existing in the background art.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] On the one hand, the present invention provides an optimized method for empty container relocation that considers multiple modes of transportation, including:

[0012] Construct a multimodal transport network for empty containers, G = (N, A), where N represents the set of points and A represents the set of arcs; let N = P∪I∪J represent the set of all nodes; set P consists of ports p; set I represents freight stations near ports; set J represents inland container freight stations; A includes road transport arcs between ports and freight stations near ports, as well as road or rail transport arcs between freight stations near ports and inland container freight stations, and between different inland container freight stations.

[0013] Based on the constructed sea-rail-road multimodal transport empty container dispatching network, an integer programming model for multimodal transport empty container dispatching is constructed with the goal of minimizing total cost; where total cost includes empty container leasing cost, empty container storage cost, and total inland empty container dispatching cost;

[0014] Solve the integer programming model for the transfer of empty containers in multimodal transport to determine the optimal amount of empty containers transferred between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

[0015] Furthermore, the construction of an integer programming model for multimodal transport empty container repositioning includes container demand constraints: demand for freight stations near ports. via port lease Inventory at the beginning of the planning period Empty containers returned by customers To meet the needs of inland container freight stations From the cargo station near the port Other inland container freight stations lease Initial inventory planning Empty boxes returned by customers To satisfy.

[0016] Furthermore, the multimodal transport empty container relocation integer programming model includes inventory capacity constraints: at the beginning of the planning period (t=1, t∈T), for any given node, the existing inventory of that node is equal to the initial inventory of that node; at the beginning of the planning period t (t>1, t∈T), the inventory of each node includes: the sum of the remaining inventory of the previous period, the number of empty containers transported from other nodes, the number of leased containers of the previous period, and the number of empty containers returned by customers, minus the number of empty containers already transported out of that node; the inventory of each node in each planning period cannot exceed the capacity limit of that node.

[0017] Furthermore, the multimodal transport empty container relocation integer programming model includes container flow constraints: the number of empty containers transferred from freight station i near the port to other freight stations during period t. and the number of empty containers to meet the demand Cannot exceed inventory Container rental Customer returns empty box and the number of empty containers transported from the port The sum; the number of empty containers transferred from freight station u to other freight stations during decision period t. and the number of empty containers to meet the demand Cannot exceed inventory Container rental Empty boxes returned by the customer Empty containers from other freight stations The sum; the number of empty containers delivered to other freight stations at time t. The number of containers shipped from overseas shall not exceed y t The sum of the inventory at port P.

[0018] Furthermore, the construction of the multimodal transport empty container relocation integer programming model includes transport capacity constraints: the number of empty containers relocated by transport mode m. It cannot exceed the transport capacity of the line.

[0019] Furthermore, the decision variables in the multimodal transport empty container repositioning integer programming model are divided into three groups: the first group includes variables related to leasing, denoted as... The second group consists of variables related to container flow, namely The last group includes inventory-related variables.

[0020] Secondly, the present invention provides a container empty container relocation optimization system that considers multiple modes of transportation, comprising:

[0021] The first construction module is used to construct the sea-rail-road multimodal transport empty container dispatch network G = (N, A), where N represents the set of points and A represents the set of arcs; let N = P∪I∪J represent the set of all nodes; set P consists of ports p; set I represents freight stations near ports; set J represents inland container freight stations; A includes road transport arcs between ports and freight stations near ports, as well as road or rail transport arcs between freight stations near ports and inland container freight stations, and between different inland container freight stations;

[0022] The second construction module is used to construct an integer programming model for multimodal transport empty container dispatching based on the constructed sea-rail-road multimodal transport empty container dispatching network, with the goal of minimizing the total cost; where the total cost includes empty container leasing cost, empty container storage cost, and total inland empty container dispatching cost;

[0023] The solution module is used to solve the integer programming model for multimodal empty container relocation, and to determine the optimal empty container relocation volume between ports and container freight stations, the empty container leasing volume of each container freight station in each planning period, and the empty container inventory.

[0024] Thirdly, the present invention provides a non-transitory computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the container empty container relocation optimization method considering multiple modes of transportation as described above.

[0025] Fourthly, the present invention provides a computer device including a memory and a processor, wherein the processor and the memory communicate with each other, the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the container empty container relocation optimization method considering multiple modes of transportation as described above.

[0026] Fifthly, the present invention provides an electronic device, comprising: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the container empty container relocation optimization method considering multiple modes of transportation as described above.

[0027] The beneficial effects of this invention are as follows: It considers the combination of multiple transportation modes, including road, rail, and water transport, and solves the container air-conditioning transportation problem under multiple transportation modes, thus fully leveraging the advantages of each mode. It takes into account various types of container freight stations, dividing them into two main categories based on actual container operation: container freight stations near ports and inland container freight stations. Furthermore, based on the available transportation modes, these freight stations are subdivided into railway container freight stations and road container freight stations to meet different transportation needs, especially the need for empty container relocation. A multi-period empty container relocation model is constructed, enabling multi-period decision-making to determine the amount of empty containers relocated on each transportation route, the number of leased empty containers, the inventory of container freight stations in each decision-making period, and the selected transportation mode for each transportation route.

[0028] The advantages of additional aspects of the invention will be set forth more clearly in the following description or will be learned by practice of the invention. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the multimodal transport network for empty container handling as described in an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of container flow balance according to an embodiment of the present invention. Wherein, Figure 2 (a) is a freight station (i) near the port. Figure 2 (b) is an inland container freight station (u). Figure 2 (c) is the port (p).

[0032] Figure 3 This is a schematic diagram illustrating the complexity analysis described in an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram illustrating the empty container transportation results according to an embodiment of the present invention. Figure 4 (a) is t=1, Figure 4 (b) is t=2, Figure 4 (c) is t=3. Figure 4 (d) is t=4. Figure 4 (e) is t=5. Figure 4 (f) is t=6, Figure 4 (g) is t=7 Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0036] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0037] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0038] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0039] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0040] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0041] Example 1

[0042] In this embodiment 1, a container empty container relocation optimization system considering multiple transportation modes is first provided. This system includes: a first construction module for constructing a sea-rail-road multimodal transport empty container relocation network G = (N, A), where N represents the set of points and A represents the set of arcs; let N = P∪I∪J represent the set of all nodes; set P consists of ports p; set I represents freight stations near the ports; set J represents inland container freight stations; A includes road transport arcs between ports and freight stations near ports, and between freight stations near ports and inland container freight stations. The first module is a road or rail transport arc between transport stations and between different inland container freight stations; the second module is a construction module used to build an integer programming model for multimodal transport empty container transfer based on the constructed sea-rail-road multimodal transport empty container transfer network, with the goal of minimizing the total cost; the total cost includes empty container leasing cost, empty container storage cost, and total inland empty container transfer cost; the third module is a solution module used to solve the multimodal transport empty container transfer integer programming model to determine the optimal empty container transfer volume between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

[0043] Using the above system, an optimization method for empty container relocation considering multiple modes of transportation was implemented, including: constructing a multimodal transport empty container relocation network G = (N, A); based on the constructed multimodal transport empty container relocation network, constructing an integer programming model for multimodal transport empty container relocation with the objective of minimizing total cost; wherein, the total cost includes empty container leasing cost, empty container storage cost, and inland empty container relocation total cost; solving the multimodal transport empty container relocation integer programming model to determine the optimal empty container relocation volume between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

[0044] The construction of the multimodal transport empty container repositioning integer programming model includes container demand constraints: demand for freight stations near the port. via port lease Inventory at the beginning of the planning period Empty containers returned by customers To meet the needs of inland container freight stations From the cargo station near the port Other inland container freight stations lease Initial inventory planning Empty boxes returned by customers To satisfy.

[0045] The multimodal transport empty container relocation integer programming model includes inventory capacity constraints: at the beginning of the planning period (t=1, t∈T), for any given node, the existing inventory of that node is equal to the initial inventory of that node; at the beginning of the planning period t (t>1, t∈T), the inventory of each node includes: the sum of the remaining inventory of the previous period, the number of empty containers transported from other nodes, the number of leased containers of the previous period, and the number of empty containers returned by customers, minus the number of empty containers already transported out of that node; the inventory of each node in each planning period cannot exceed the capacity limit of that node.

[0046] The multimodal transport empty container relocation integer programming model includes container flow constraints: the number of empty containers transferred from freight station i near the port to other freight stations during period t. and the number of empty containers to meet the demand Cannot exceed inventory Container rental Customer returns empty box and the number of empty containers transported from the port The sum; the number of empty containers transferred from freight station u to other freight stations v during decision period t. and the number of empty containers to meet the demand Cannot exceed inventory Container rental Empty boxes returned by the customer Empty containers from other freight stations The sum; the number of empty containers delivered to other freight stations at time t. The number of containers shipped from overseas shall not exceed y t The sum of the inventory at port P.

[0047] The construction of an integer programming model for the repositioning of empty containers in multimodal transport includes a transport capacity constraint: the number of empty containers repositioned by transport mode m. It cannot exceed the transport capacity of the line.

[0048] The decision variables in the multimodal transport empty container repositioning integer programming model are divided into three groups: the first group includes variables related to leasing, denoted as... The second group consists of variables related to container flow, namely The last group includes variables related to inventory.

[0049] Example 2

[0050] In this embodiment 2, an optimized method for empty container relocation considering multiple transportation modes is provided. Container freight stations are subdivided: port-adjacent and inland container freight stations are considered, further divided into railway and road container freight stations. The method also considers a combination of water, road, and rail transport for empty container relocation, which better matches the actual container freight practices in China. Addressing the shortcomings of existing technologies, the method provided in this embodiment focuses on solving the following key problems: Multiple container freight stations: It considers various types of container freight stations, including those located near ports and inland. These stations are further divided into railway and road container freight stations to better reflect the actual situation. Multiple transportation modes: It considers the combined relocation of empty containers using multiple transportation modes such as sea, road, and rail to fully utilize the advantages of each mode and make relocation more efficient. Multi-period model: A multi-period empty container relocation model is constructed. The proposed model can determine the amount of empty containers relocated on each transportation route, the number of leased empty containers, the inventory of container freight stations in each decision period, and the selected transportation mode for each transportation route.

[0051] Specifically, the container empty container relocation optimization method considering multiple modes of transportation described in this embodiment includes the following steps:

[0052] (1) Construction of a multimodal transport network for empty containers involving sea, rail and road

[0053] In this embodiment, an empty container dispatching network combining sea, rail, and road transportation is constructed, denoted by G = (N, A). Figure 1 (As shown) where N represents the point set and A represents the arc set, this network combines multiple modes of transportation, including sea, rail and road, to facilitate the redistribution of empty containers.

[0054] Let N = P∪I∪J denote the set of all nodes. Set P consists of ports p, which are nodes for container transshipment by sea and land, capable of storing a limited number of containers but generating no demand. Set I represents freight stations near the ports. Set J represents inland container freight stations. Both sets I and J include both railway container freight stations and road container freight stations.

[0055] A represents an arc, primarily including road transport arcs between ports and nearby freight stations, as well as road or rail transport arcs between nearby freight stations and inland container freight stations, and between different inland container freight stations. Regulations stipulate that only two railway container freight stations can conduct railway container transport, and the direction of empty container transport is unidirectional, i.e., from the port end to the container freight station. The demand of nearby freight stations can only be met by empty containers returned by the port and customers, without considering the situation of empty containers being transported from inland areas to the port.

[0056] The container transportation process comprises two parts: overseas relocation and inland empty container transportation. (a) In the first stage, logistics companies regularly order empty containers from overseas ports. At the beginning of each planning period, the ordered empty containers arrive at the port. The number of empty containers arriving is predetermined. (b) In the second stage, decision-makers need to determine, based on the needs of each freight station, the number of empty containers transferred from that port to other freight stations, the mode of transport for the transferred empty containers, and the inventory quantity. If the amount of empty container transshipment still cannot meet the demand, the number of leased empty containers should be determined.

[0057] (2) Construction of Integer Programming Model for Multimodal Transport Empty Container Relocation

[0058] In this embodiment, the following assumptions are made for the construction of the integer programming model for the transshipment of empty containers in multimodal transport:

[0059] Only 40-foot containers are considered; the number of empty containers transferred from overseas in each cycle is known; there is a fixed number of trains and a predetermined available capacity for each planning period; empty containers can be leased immediately within the container freight station with no limit on the number, and the return of leased containers is not considered; containers are intact throughout the transshipment process, i.e., maintenance, depreciation and damage costs of containers are not considered.

[0060] The main objective of constructing an integer programming model for multimodal empty container relocation is to determine the optimal empty container relocation volume between ports and container freight stations, and the empty container inventory of each container freight station in each planning period, while minimizing total cost. The total cost of the problem consists of three parts: Z1 represents the empty container leasing cost, including container leasing costs near the port. and inland container freight station leasing costs Z2 represents the cost of storing empty containers, including storage costs at freight stations near the port. Inland container freight station leasing costs and port empty container inventory costs Z3 represents the total cost of inland empty container relocation, including transportation costs between the port and nearby freight stations. Transportation costs between port-adjacent freight stations and inland container freight stations Transportation costs between inland container freight stations

[0061]

[0062]

[0063]

[0064] min Z=Z1+Z2+Z3 (4)

[0065] Container demand constraints: Constraints (5) and (6) indicate that the demand of each freight station must be met. Demand for freight stations near the port. via port lease Inventory at the beginning of the planning period Empty containers returned by customers To meet the needs of inland container freight stations. From the cargo station near the port Other inland container freight stations lease Initial inventory planning Empty boxes returned by customers To satisfy.

[0066]

[0067]

[0068] Inventory capacity constraints: Constraints (7), (9), and (11) indicate that at the start of the planning period (t = 1, t ∈ T), for any given node, the existing inventory of that node is equal to the initial inventory of that node. Constraints (8), (10), and (12) indicate that at the start of the planning period t (t > 1, t ∈ T), the inventory of each node includes: the remaining inventory from the previous period, the number of empty containers transported from other nodes, the number of leased containers from the previous period, and the number of empty containers returned by customers, minus the number of empty containers already shipped out of that node (transferred to other freight stations or to meet customer demand). Constraints (13), (14), and (15) indicate that the inventory of each node in each planning period cannot exceed the capacity limit of that node.

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078] Container flow constraints: such as Figure 2As shown, (a) represents the container flow at freight stations near the port. During period t, the number of empty containers transferred from freight station i near the port to other freight stations. and the number of empty containers to meet the demand Cannot exceed inventory Container rental Customer returns empty box and the number of empty containers transported from the port The sum (see constraint (16)). (b) is the container flow of inland container freight stations. The number of empty containers transferred from freight station u to other freight stations during decision period t. and the number of empty containers to meet the demand Cannot exceed inventory Container rental Empty boxes returned by the customer Empty containers from other freight stations The sum. (See constraint (17)). (c) represents the container flow at port p, and the number of empty containers delivered to other freight stations at time t. The number of containers shipped from overseas shall not exceed y t The sum of the inventory at port p (see constraint (18)).

[0079]

[0080]

[0081]

[0082] Transport capacity constraints: Constraints (19) and (20) represent the number of empty containers transported by transport mode m (m∈M). It cannot exceed the transport capacity of the line.

[0083]

[0084]

[0085]

[0086] Standardization constraints: Constraint (21) represents the standard non-negative integer variables of the model.

[0087] (3) Complexity analysis of the model

[0088] The decision variables in this model can be divided into three groups. The first group includes variables related to leasing, denoted as... The second group consists of variables related to container flow, namely The last group includes variables related to inventory, such as... This section provides a detailed analysis of the complexity of the proposed model, including the total number of variables involved in the problem and key constraints. Table 1 summarizes this information.

[0089] Table 1 Number of decision variables and constraints

[0090]

[0091] Clearly, the complexity of the proposed model depends primarily on the size of certain sets, namely the number of freight stations (i.e., |I|, |J|), ports (i.e., |P|)), modes of transport (i.e., |M|), and planning period (i.e., |T|). These factors directly affect the number of decision variables and constraints in the model, ultimately influencing its computational complexity.

[0092] To clearly illustrate this relationship, Table 2 provides several examples. In this invention, it is assumed that the number of ports and their nearby freight stations is fixed, so we only discuss variations in inland container freight stations and time periods. By changing the size of the above sets, the number of decision variables and constraints will also change accordingly. Figure 3 As shown, the number of constraints increases exponentially with the increase in the number of container freight stations.

[0093] Table 2 Complexity Analysis

[0094]

[0095]

[0096] In this embodiment 2, with Figure 1 A computational example was designed using a network consisting of one port, two nearby container freight stations, and ten inland container freight stations. The two nearby port freight stations are a railway container freight station and a road container freight station, respectively. The ten inland container freight stations include four railway container freight stations and six road container freight stations. The planning cycle is seven days. Based on the model proposed in this invention, the solution was obtained using the solver software CPLEX. The final empty container relocation results are as follows: Figure 4 As shown.

[0097] Example 3

[0098] This embodiment 3 provides a non-transitory computer-readable storage medium for storing computer instructions. When executed by a processor, the computer instructions implement the container empty container relocation optimization method considering multiple transportation modes as described above. The method includes:

[0099] Construct a multimodal transport network for empty containers, G = (N, A), where N represents the set of points and A represents the set of arcs; let N = P∪I∪J represent the set of all nodes; set P consists of ports p; set I represents freight stations near ports; set J represents inland container freight stations; A includes road transport arcs between ports and freight stations near ports, as well as road or rail transport arcs between freight stations near ports and inland container freight stations, and between different inland container freight stations.

[0100] Based on the constructed sea-rail-road multimodal transport empty container dispatching network, an integer programming model for multimodal transport empty container dispatching is constructed with the goal of minimizing total cost; where total cost includes empty container leasing cost, empty container storage cost, and total inland empty container dispatching cost;

[0101] Solve the integer programming model for the transfer of empty containers in multimodal transport to determine the optimal amount of empty containers transferred between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

[0102] Example 4

[0103] This embodiment 4 provides a computer device, including a memory and a processor, wherein the processor and the memory communicate with each other, the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute a container empty container relocation optimization method considering multiple transportation modes, the method including:

[0104] Construct a multimodal transport network for empty containers, G = (N, A), where N represents the set of points and A represents the set of arcs; let N = P∪I∪J represent the set of all nodes; set P consists of ports p; set I represents freight stations near ports; set J represents inland container freight stations; A includes road transport arcs between ports and freight stations near ports, as well as road or rail transport arcs between freight stations near ports and inland container freight stations, and between different inland container freight stations.

[0105] Based on the constructed sea-rail-road multimodal transport empty container dispatching network, an integer programming model for multimodal transport empty container dispatching is constructed with the goal of minimizing total cost; where total cost includes empty container leasing cost, empty container storage cost, and total inland empty container dispatching cost;

[0106] Solve the integer programming model for the transfer of empty containers in multimodal transport to determine the optimal amount of empty containers transferred between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

[0107] Example 5

[0108] This embodiment 5 provides an electronic device, including: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the container empty container relocation optimization method considering multiple transportation modes as described above. The method includes:

[0109] Construct a multimodal transport network for empty containers, G = (N, A), where N represents the set of points and A represents the set of arcs; let N = P∪I∪J represent the set of all nodes; set P consists of ports p; set I represents freight stations near ports; set J represents inland container freight stations; A includes road transport arcs between ports and freight stations near ports, as well as road or rail transport arcs between freight stations near ports and inland container freight stations, and between different inland container freight stations.

[0110] Based on the constructed sea-rail-road multimodal transport empty container dispatching network, an integer programming model for multimodal transport empty container dispatching is constructed with the goal of minimizing total cost; where total cost includes empty container leasing cost, empty container storage cost, and total inland empty container dispatching cost;

[0111] Solve the integer programming model for the transfer of empty containers in multimodal transport to determine the optimal amount of empty containers transferred between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

[0112] In summary, the container empty container relocation optimization method considering multiple transportation modes described in this invention solves the bottlenecks in existing empty container relocation problems, improves transportation efficiency, reduces costs, and promotes sustainable logistics and transportation. This method simultaneously considers multiple transportation modes such as rail, road, and waterway to jointly relocate empty containers. By utilizing sea transport to relocate large numbers of empty containers from regions primarily importing containers to regions primarily exporting containers, and then transferring them to the port hinterland via rail and road, it can fully leverage the advantages of sea transport's large volume and low cost, and the high flexibility and speed of rail and road transport, effectively reducing overall transportation costs. Various types of container freight stations are considered, and based on actual container operation, container freight stations are divided into port-adjacent container freight stations and inland container freight stations. Furthermore, according to the available transportation modes, freight stations are subdivided into railway container freight stations and road container freight stations to meet the actual needs of relocating empty containers using multiple transportation modes. A multi-cycle empty container dispatching model was constructed. The proposed model can realize multi-cycle decision-making, determine the dispatching volume of empty containers on each transportation route in each cycle, the number of leased empty containers, the inventory of container freight stations in each decision cycle, and the transportation mode selected for each transportation route.

[0113] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0114] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0115] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0116] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, whereby a series of operational steps are performed to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0117] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. A method for optimizing the relocation of empty containers considering multiple modes of transportation, characterized in that, include: Building a multimodal transport network for empty containers integrating sea, rail, and road ,in represents a point set, Represent the arc set; let A set representing all nodes; a set From the port Composition; set Indicates a freight station near a port; a collection Indicates an inland container freight station; This includes road transport arcs between ports and nearby freight stations, as well as road or rail transport arcs between nearby freight stations and inland container freight stations, and between different inland container freight stations. Based on the constructed sea-rail-road multimodal transport empty container dispatching network, an integer programming model for multimodal transport empty container dispatching is constructed with the objective of minimizing total cost. The total cost includes empty container leasing costs, empty container storage costs, and the total cost of inland empty container dispatching. The construction of the multimodal transport empty container dispatching integer programming model includes container demand constraints: demand on freight stations near ports. via port ,lease Inventory at the beginning of the planning period Empty containers returned by customers To meet the needs of inland container freight stations From the freight station near the port Other inland container freight stations ,lease Initial inventory planning Empty boxes returned by customers To meet the requirements; constructing an integer programming model for the relocation of empty containers in multimodal transport includes inventory capacity constraints: during the planning period Initially, for any given node, the node's current inventory equals its initial inventory; At the start of the planning period, the inventory at each node includes: the remaining inventory from the previous period, the number of empty containers transported from other nodes, the number of leased containers from the previous period, and the number of empty containers returned by customers, minus the number of empty containers already shipped out of that node; the inventory at each node during each planning period cannot exceed the capacity limit of that node. Solve the integer programming model for the transfer of empty containers in multimodal transport to determine the optimal amount of empty containers transferred between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

2. The method for optimizing the relocation of empty containers considering multiple modes of transportation as described in claim 1, characterized in that, Constructing an integer programming model for multimodal empty container repositioning includes container flow constraints: During this period, from the cargo station near the port Number of empty containers transferred to other freight stations and the number of empty containers to meet the demand Cannot exceed inventory Container leasing Customer returns empty boxes and the number of empty containers transported from the port The sum; in During the decision-making period, freight stations Number of empty containers transferred to other freight stations and the number of empty containers to meet the demand Cannot exceed inventory t, leased containers Empty boxes returned by customers Empty containers from other freight stations , sum; in The number of empty containers delivered to other freight stations at any time The number of containers shipped from overseas shall not exceed and The sum of Hong Kong's inventory.

3. The method for optimizing the relocation of empty containers considering multiple modes of transportation according to claim 2, characterized in that, Constructing an integer programming model for the repositioning of empty containers in multimodal transport includes transport capacity constraints: based on transport mode Number of empty containers transported It cannot exceed the transport capacity of the line. .

4. The method for optimizing the relocation of empty containers considering multiple modes of transportation according to claim 3, characterized in that, The decision variables in the multimodal transport empty container repositioning integer programming model are divided into three groups: the first group includes variables related to leasing, denoted as... The second group consists of variables related to container flow, namely... The last group includes variables related to inventory.

5. A container empty container relocation optimization system considering multiple modes of transportation, characterized in that, include: The first building module is used to construct a multimodal transport network for empty containers, integrating sea, rail, and road transport. ,in represents a point set, Represent the arc set; let A set representing all nodes; a set From the port Composition; set Indicates a freight station near a port; a collection Indicates an inland container freight station; This includes road transport arcs between ports and nearby freight stations, as well as road or rail transport arcs between nearby freight stations and inland container freight stations, and between different inland container freight stations. The second construction module is used to build an integer programming model for multimodal empty container relocation based on the constructed sea-rail-road multimodal transport empty container relocation network, with the objective of minimizing the total cost. The total cost includes empty container leasing costs, empty container storage costs, and the total cost of inland empty container relocation. The construction of the multimodal empty container relocation integer programming model includes container demand constraints: the demand for freight stations near ports. via port ,lease Inventory at the beginning of the planning period Empty containers returned by customers To meet the needs of inland container freight stations From the freight station near the port Other inland container freight stations ,lease Initial inventory planning Empty boxes returned by customers To meet the requirements; constructing an integer programming model for the relocation of empty containers in multimodal transport includes inventory capacity constraints: during the planning period Initially, for any given node, the node's current inventory equals its initial inventory; At the start of the planning period, the inventory at each node includes: the remaining inventory from the previous period, the number of empty containers transported from other nodes, the number of leased containers from the previous period, and the number of empty containers returned by customers, minus the number of empty containers already shipped out of that node; the inventory at each node during each planning period cannot exceed the capacity limit of that node. The solution module is used to solve the integer programming model for multimodal empty container relocation, and to determine the optimal empty container relocation volume between ports and container freight stations and the empty container inventory of each container freight station in each planning period.

6. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the container empty container relocation optimization method considering multiple modes of transportation as described in any one of claims 1-4.

7. A computer device, characterized in that, The system includes a memory and a processor, which communicate with each other. The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the container empty container relocation optimization method considering multiple modes of transportation as described in any one of claims 1-4.

8. An electronic device, characterized in that, include: The electronic device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the container empty container relocation optimization method considering multiple modes of transportation as described in any one of claims 1-4.

Images