CN113313331A - Emergency material multi-cycle segmentation distribution method and device based on inventory gap risk - Google Patents
Emergency material multi-cycle segmentation distribution method and device based on inventory gap risk Download PDFInfo
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Abstract
The invention discloses an emergency material multi-period segmentation distribution method and device based on inventory gap risks, wherein the method comprises the following steps: dividing the total time of the emergency plan into a plurality of scheduling periods at preset period intervals; for any material point, dividing the material point into a plurality of equal-part virtual node sets according to the capacity; solving the multi-cycle vehicle path model to obtain a material scheduling scheme of the current scheduling cycle, executing the material scheduling scheme of the current scheduling cycle, updating the reserve quantity of material points, and updating the service state of the virtual nodes according to the material scheduling scheme; and calculating material gaps of each material point at the end of the current scheduling period according to the preset period interval and the material consumption speed, updating the service state of the virtual node according to the preset period interval and the material consumption speed, updating the objective function of the multi-period vehicle path model, and entering the calculation of the next scheduling period. The invention can generate the sequence of using and visiting the stations of the vehicle at the execution level, so that the optimization result has more actual reference value.
Description
Technical Field
The invention relates to the technical field of material distribution and vehicle routing, in particular to an emergency material multi-period segmentation distribution method and device based on inventory gap risks.
Background
Various sudden disaster accidents have serious destructiveness, which causes great damage to the daily life of people. After a disaster accident occurs, emergency materials need to be delivered to a disaster site. In the prior art, the problem of multi-cycle emergency material distribution only concerns the problem of material distribution, namely only concerns the destination and the corresponding quantity of material sources, and an economically feasible vehicle path scheme is not provided.
Disclosure of Invention
The invention solves the problem that the existing material distribution problem does not provide an economically feasible vehicle path scheme.
The invention provides an emergency material multi-period segmentation distribution method based on inventory gap risks, which comprises the following steps:
step 1: dividing the total time length of the emergency plan into a plurality of dispatching cycles at preset cycle intervals, using i to represent the serial numbers of the dispatching cycles,(ii) a For any material point, dividing the material point into material points according to capacityA set of virtual nodes that are equal in size,;
step 2: solving the multi-cycle vehicle path model to obtain the firstMaterial scheduling scheme of scheduling periodExecution of the firstA material scheduling scheme for each scheduling period;
and step 3: after the execution is finishedAfter the material scheduling scheme of each scheduling period, updating the reserve quantity of material points, and updating the service state of the virtual nodes according to the material scheduling scheme;
and 4, step 4: calculating material gaps of each material point at the end of the current scheduling period according to the preset period interval and the material consumption speed, updating a virtual node service state according to the preset period interval and the material consumption speed, and updating a target function of the multi-period vehicle path model;
Optionally, the objective function of the multi-cycle vehicle path model is:
wherein the content of the first and second substances,for a positive number greater than the preset value,a fleet set is represented as a set of vehicles,represents a vehicle number, 0 represents a distribution center,a set of virtual nodes is represented that is,、each of which represents a virtual node,representative arcThe driving distance of the vehicle is set to be,is shown asThe decision variables of the cycle are varied in such a way that,indicating the value of the access reward,the status of the service is indicated,representing virtual nodesThe corresponding inventory gap space-time risk,indicating that the preset period interval is set to be,representing virtual nodesCorresponding material pointAt said predetermined periodic intervalsThe integral of the inner one of the two,for material pointThe size of the (c) is (d),for material pointThe risk factor of inventory gaps of (a),for material pointThe number of the capacity is divided into parts,first fingerThe time of execution of the periodic scheduling scheme.
Optionally, the updating the service state of the virtual node according to the material scheduling scheme includes:
setting the service states of all accessed virtual nodes in the emergency plan of the current scheduling period asSetting the service state of the nodes with preset number for the virtual nodes which are not served in the emergency plan of the current scheduling period。
Optionally, the preset number is:
wherein the content of the first and second substances,as the ith period material pointThe minimum amount of the delivery of the liquid,for material pointThe total capacity of (c).
Alternatively,
wherein the content of the first and second substances,for material pointThe minimum guaranteed amount of reserve of the tank,the speed of the consumption of the material is shown,reserve the amount of materials before dispatching.
Optionally, the updating the service state of the virtual node according to the preset cycle interval and the material consumption speed includes:
calculating the number of virtual nodes to be consumed according to the material consumption speed in the preset period interval, and setting the service state of the part of virtual nodes as。
Optionally, the constraint conditions of the multi-cycle vehicle path model are:
wherein the decision variablesRepresentative vehicleWhether or not to pass through arcAnd 0 represents a number of the distribution center,is a set of nodes to be served,is a collection of a fleet of vehicles,which represents the number of the vehicle,is a node to be served by a node,representsThe amount of demand for the point(s),is a collection of network arcs and is,represents a segment of an arc in the network,representsThe arc-out of the point is realized,representsThe arc-in of the point is formed,set of representative material pointsAll of the arc-out points of (c),indicating vehiclesWhether or not to pass through arc。
Optionally, the method further comprises:
presetting a value range of a stock gap risk coefficient and the preset period interval;
respectively executing the steps 1-5 according to parameter combinations composed of different inventory gap risk coefficients and preset period intervals to obtain material scheduling schemes under different parameter combinations and corresponding transportation cost and risk cost;
and normalizing the transportation cost and the risk cost of all the material scheduling schemes, calculating the weighted sum to obtain dimensionless comprehensive cost, determining the material scheduling scheme with the lowest comprehensive cost and the corresponding optimal parameter combination thereof, and taking the material scheduling scheme with the lowest comprehensive cost as the optimal scheme for multi-period emergency material scheduling.
The invention further provides an emergency material multi-period segmentation and distribution device based on the inventory gap risk, which comprises a computer readable storage medium and a processor, wherein the computer readable storage medium stores a computer program, and the computer program is read by the processor and runs to realize the emergency material multi-period segmentation and distribution method based on the inventory gap risk.
The invention further provides a computer-readable storage medium, which stores a computer program, and when the computer program is read and executed by a processor, the method for multi-cycle segmentation and distribution of emergency materials based on the risk of inventory gaps is implemented.
The multi-cycle vehicle path problem model which is constructed under different risk estimations and takes the reward collection, the division and the distribution as well as the capacity constraint into consideration not only pays attention to the material source and the destination, but also generates the vehicle use, the station access sequence and the like of the logistics scheme execution level, so that the optimization result has more actual reference value, and the utilization efficiency of the transportation resource is improved; the invention divides the material points into the virtual node sets according to the capacity so as to split the requirements of the material points, thereby improving the full load rate of vehicles and the utilization efficiency of transportation resources; the invention considers the periodic initial gap risk in the multi-period vehicle path model by utilizing the reward collection mechanism, in the reward collection model, the vehicle does not need to visit all demand points any more, but encourages the vehicle to visit the distribution points with higher priority preferentially through a certain reward mechanism, and under the condition that the transportation resources are limited in the actual emergency material scheduling scene, the material scheduling scheme can preferentially ensure the material supply of the region with higher potential risk so as to reduce the global loss.
Drawings
FIG. 1 is a schematic diagram showing the reserve amount of material points in the first 3 periods as a function of time;
FIG. 2 is a schematic diagram of an embodiment of a multi-cycle division distribution method for emergency materials based on risk of inventory gaps according to the present invention;
FIG. 3 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 0;
FIG. 4 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 1;
FIG. 5 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 2;
FIG. 6 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 3;
FIG. 7 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 4;
FIG. 8 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 5;
FIG. 9 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 6;
FIG. 10 is a schematic plan view of an emergency materials dispatch vehicle routing scheme at time step 7;
FIG. 11 is a schematic plan view of an emergency materials dispatch vehicle path plan at time step 8;
FIG. 12 is a three-dimensional schematic diagram of an emergency material dispatching vehicle path scenario at time steps 0-60;
fig. 13 is a schematic diagram of the logistics cost and the risk of the inventory gap with an estimated risk coefficient f =1 and a preset period interval T = 1;
fig. 14 is a schematic diagram of the estimated risk coefficient f =9 and the logistics cost and the inventory gap risk at the preset cycle interval T = 1;
fig. 15 is a schematic diagram of the estimated risk coefficient f =22 and the logistics cost and the inventory gap risk at the preset cycle interval T = 1;
FIG. 16 is a multi-dimensional spatial schematic of the composite cost at different estimated risk factors and preset periodic intervals;
fig. 17 shows the variation of the logistics cost with the estimated risk coefficient on the premise of a certain preset period interval;
fig. 18 is a diagram showing the change of the logistics cost with the preset period interval on the premise that the estimated risk coefficient is fixed;
FIG. 19 is a diagram showing the variation of the gap risk of the materials with the estimated risk coefficient under the premise of a certain interval of the preset period;
fig. 20 shows the variation of the material gap risk with the preset period interval on the premise that the estimated risk coefficient is constant.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
To facilitate understanding of the present invention, key words related to the present invention are briefly explained.
Vehicle Routing Problem (VRP) is the set of best routes to travel to provide travel services for a group of customers to solve a group of vehicles. The multi-period material scheduling refers to performing multiple times of material scheduling according to different period intervals in a longer time, and searching for an optimal combined scheduling scheme under different periods. In conventional research, the multi-cycle scheduling problem is modeled as an allocation/assignment problem, generally without concern for logistics-related attributes such as specific vehicle transportation paths and vehicle capacities/quantities. The present invention addresses the multi-cycle Vehicle Routing Problem (VRP) whose solution is a specific set of performable vehicle access site sequences, including the number of vehicles used and the corresponding vehicle capacities.
Periodically needing emergency materials: the emergency supplies can be divided into disposable demand supplies (such as quilts and tents) and periodic demand supplies (such as foods and sanitary supplies) according to consumption types. The type of materials researched by the invention is periodically required materials consumed regularly, one characteristic of the materials is that the materials can be lost along with time and the speed is stable, and the other characteristic is that the stock can not be lower than a certain level at any time so as to guarantee the emergency disaster relief requirement.
Risk of inventory gaps: the shortage of points presents a potential risk, which is affected by the size of the points (serving area/population).
And (3) reward collection: in the reward collection model, the vehicle no longer needs to visit all demand points, but rather is encouraged to visit higher priority (potentially high risk) delivery points preferentially by some reward mechanism. In the case of limited resources, the optimization scheme will prioritize the higher risk of service material points to minimize global losses.
Referring to fig. 2, in an embodiment of the emergency material multi-cycle distribution method based on the risk of inventory gaps, the multi-cycle distribution method includes:
step 1:
step 1.1: and dividing the total time of the emergency plan into a plurality of scheduling periods at preset period intervals. And generating a corresponding material scheduling scheme in each scheduling period, and distributing materials for corresponding material points.
Wherein, i represents the sequence number of the scheduling cycle,and the initial value of i is 0. The predetermined period interval is a fixed time interval,Using a set of exponential integers, using a predetermined periodic intervalWill total time length ofIs divided intoIn each scheduling period, the sequence number set of the scheduling period is as follows:
the execution time of the material scheduling scheme is generally far less than the scheduling periodThe multicycle vehicle path model assumes that it begins at each cycleAnd executing the material scheduling scheme at any moment to finish material scheduling (the process shown by a black solid line in figure 1).
Set the coverage of the emergency planIndividual material points, each material pointHas a total capacity ofThe minimum guaranteed reserve is. In thatAt the moment, the reserve amount of materials before dispatching isThe scheduled material reserve amount is. The reserve amount of each material point is supplemented after the material scheduling, and the period isInternal natural losses. The reserve quantity of the material points in any period needs to meet the following constraint:
wherein the content of the first and second substances,is as followsPeriodic material scheduling scheme at material pointsTotal delivery amount of (c).
Step 1.2: for any material point, dividing the material point into material points according to capacityEqual parts of virtual node sets.
For any material pointWill capacity ofIs divided intoEqual parts of virtual node setOriginal network non-distribution center node setIs divided into virtual node setsThe logistics cost between the virtual nodes is 0. Put the material pointAfter cuttingA virtual node is represented asVirtual nodeMaterial demand ofComprises the following steps:
based on the above virtual nodeMaterial point pair by periodic material scheduling schemeTotal material demand for replenishmentComprises the following steps:
wherein the content of the first and second substances,
is as followsThe periodic material scheduling scheme decision variables,to representIn the form of a virtual node, the node is,to representAs a set of virtual nodesAnd in distribution center node andthe number of different nodes is such that,refers to the upper limit of the capacity of the vehicle,finger-shapedThe amount of demand for the point(s),is a collection of a fleet of vehicles,representing the vehicle number.
Since the demand for a single material point may exceed the capacity of the vehicle, a limited capacity of vehicles may be used for co-transportation for demand splits. And the demands of different material points are different, and the full load rate of the vehicle can be improved by adopting segmentation delivery.
Before the step 1-step 5 are executed, initializing material point data, vehicle parameters and a plan total duration L, wherein the material point data comprises data such as material point positions and material point specifications, and the vehicle parameters comprise vehicle capacity; and set a period intervalRisk factor of gap of material,The value is assigned to 0.
Step 2: solving the multi-cycle vehicle path model to obtain the firstA material scheduling scheme for each scheduling cycle is performedAnd (4) a material scheduling scheme of each scheduling period.
The multi-cycle vehicle path model can be solved by adopting a local search algorithm, and the solving method is the prior art and is not described herein. The directly obtained solution is a set of virtual node access sequences, for example, in a physical site ID (virtual node number) format, there are physical sites 1-9, and the solution may be 1(0) -1(1) -3(0) -6 (0) -9 (0), that is, the access sequence is: virtual node No. 0 of physical site 1-virtual node No. 1 of physical site 1-virtual node No. 0 of physical site 3-virtual node No. 0 of physical site 9. Based on the obtained solution, an executable vehicle access station sequence may be further generated, and if a plurality of virtual nodes of the same physical station are consecutively accessed in one solution, only one physical station is reserved in the vehicle access station sequence generated based on the solution, for example, assuming that the solution is: 1(0) -1(1) -3(0) -6 (0) -9 (0), the obtained vehicle access station sequence is: 1-3-6-9, assuming the solution is: 1(2) -3(1) -6 (0) -9 (0), the obtained vehicle visiting station sequence is also: 1-3-6-9.
The optimization goals of the multi-cycle vehicle path model are as follows:
wherein the content of the first and second substances,for a positive number greater than the preset value,a fleet set is represented as a set of vehicles,represents a vehicle number, 0 represents a distribution center,a set of virtual nodes is represented that is,、all represent virtual sectionsThe point(s) is (are) such that,representative arcThe driving distance of the vehicle is set to be,is shown asThe decision variables of the cycle are varied in such a way that,indicating the value of the access reward,the status of the service is indicated,representing virtual nodesThe corresponding inventory gap space-time risk,indicating that the preset period interval is set to be,representing virtual nodesCorresponding material pointAt said predetermined periodic intervalsThe integral of the inner one of the two,for material pointThe size of the (c) is (d),for material pointThe risk factor of inventory gaps of (a),for material pointThe number of the capacity is divided into parts,first fingerThe time of execution of the periodic scheduling scheme.
Is a sufficiently large positive number whenValue of the prizeAt this time, the risk caused by inventory gaps in the next period interval can be reduced by supplementing materials to the corresponding virtual nodes, the risk reduction is converted into the reward for the objective function, and the target value can be obviously reduced by accessing the virtual nodes. When in useValue of the prizeAccessing the corresponding virtual node must result in a significant increase in the target value. When in useValue of the prizeIn this case, whether the access is carried out is determined by balancing the logistics cost of accessing the node and the size of the risk gap of the virtual node.
The constraints of the multi-cycle vehicle path model include:
Which represents the capacity constraint, is,indicating vehiclesWhether or not to pass through arcIf passing through, thenIf not, it is。
Wherein the decision variablesRepresentative vehicleWhether or not to pass through arcAnd 0 represents a number of the distribution center,is a set of nodes to be served,is a collection of a fleet of vehicles,which represents the number of the vehicle,is a node to be served by a node,representsThe amount of demand for the point(s),is a collection of network arcs and is,represents a segment of an arc in the network,representsThe arc-out of the point is realized,representsThe arc-in of the point is formed,set of representative material pointsAll of the arcs.
Further, in the optimization target of the multi-cycle vehicle path model, inventory gap risks are considered, the type of materials researched by the invention is periodically required materials consumed regularly, one characteristic of the materials is that the materials are lost along with time and the speed is stable, and the other characteristic is that the inventory is not lower than a certain level at any time to guarantee emergency disaster relief requirements. Fig. 1 shows the reserve amount of the material points in the first 3 periods as a function of time, in which the horizontal axis of fig. 1 is a time step, the vertical axis represents the reserve amount of the material points, and the gray part represents the current remaining reserve amount of the material. It can be observed that the material accumulation gap of each period is composed of two parts, one part is the accumulation gap of the period initial inventory gap represented by the white rectangular area in the period interval, and the other part is the accumulation gap of the additional inventory gap in the period interval caused by the material loss represented by the horizontal line triangular area. The risk value caused by the gap is positively correlated with the cumulative gap size. At the time of 2T, if the material scheduling and supplementing are not carried out on the material point, the material residual reserve is expected to not meet the guarantee requirement in the period 2. The thick dotted line represents the process that the material storage reaches the maximum capacity of the material point after the material scheduling and supplementing are carried out on the material point. The optimization goal of the multi-cycle materials scheduling model is to minimize the sum of the emergency inventory breach risk and the logistics cost of vehicle delivery for all cycles.
Since the risk value of the material points is influenced by the stock gap proportion and the gap duration, the risk value is determined for any periodTo the material pointAt periodic intervalsInner integral (trapezoidal area) as spatio-temporal risk value:
when considering the scale of the material points and the risk coefficient, the material pointsIn the first placeThe risk values due to gaps in the cycle are:
wherein the content of the first and second substances,for material pointThe size (area/population) parameter of (c),for material pointFor representing an estimate of risk of a breach.
Because the optimization target of the invention uses virtual node calculation, the material points are calculatedIn the first placeThe risk value caused by the gap in the period is converted into the virtual node at the firstRisk values caused by gaps within a cycle, in particular, virtual nodesWhen served by the material scheduling scheme, the material pointReduction of stock gap ratioThen virtual nodeCorresponding material pointAt periodic intervalsThe integral in (d) is:
and step 3: after the execution is finishedAnd after the material scheduling scheme of each scheduling period, updating the reserve quantity of the material points, and updating the service state of the virtual nodes according to the material scheduling scheme.
After the execution is finishedAfter the material scheduling scheme of each scheduling period, the material reserve of all material points or some material points is supplemented, the material point reserve is updated, and the latest reserve data is obtained.
The invention assumes that at the beginning of each cycleExecuting the material scheduling scheme at any time to complete material scheduling, so that the first time is finishedThe reserve quantity of the material points updated after the material scheduling scheme of each scheduling period isThe amount of material reserve at the beginning of each dispatch cycle.
As shown in fig. 2, at the beginning of each cycleAnd executing the material scheduling scheme at any moment, and after the material scheduling scheme is executed, updating the virtual point service state at the beginning of the period, namely updating the virtual node service state according to the material scheduling scheme. The updating the service state of the virtual node according to the material scheduling scheme comprises:
all accessed virtual nodes in the emergency plan of the current scheduling periodService state of (2) is set toWherein, in the step (A),representing the service, setting the service state of a preset number of nodes in the virtual nodes which are not served in the emergency plan of the current scheduling period,Indicating that service is necessary.
The preset number is as follows:
wherein the content of the first and second substances,is as followsPeriodic material pointThe minimum amount of the delivery of the liquid,for material pointThe total capacity of (c).
In order to prevent the remaining material at the end of the cycle from falling below the guaranteed capacity at the material point,the following constraints need to be satisfied:
wherein the content of the first and second substances,for material pointThe minimum guaranteed amount of reserve of the tank,the speed of the consumption of the material is shown,reserve the amount of materials before dispatching.
Demand splitting of material points intoVirtual node for not servedA virtual node provided thereinService state of individual nodeWherein, in the step (A),is shown asPeriodic material pointMinimum delivery volume ofDivided by the capacity of a single virtual nodeAnd then rounding up to obtain the number of virtual nodes which need to be served.
And 4, step 4: and calculating material gaps of each material point at the end of the current scheduling period according to the preset period interval and the material consumption speed, updating the service state of the virtual node according to the preset period interval and the material consumption speed, and updating the target function of the multi-period vehicle path model.
In obtaining the firstAfter the material reserve amount at the beginning of each scheduling period, the period interval length (namely the preset period interval) is used) And the material consumption rate calculates the current scheduling period (i.e. the firstEach scheduling period) ends based on the material point's material loss at the beginning of the periodAnd (4) obtaining the residual materials at the end of the period and further obtaining a material gap by the material quantity and the material loss in the whole period. For any periodMaterial pointAt periodic intervalsInternal uniform velocity lossAnd the residual materials at the end of the period are as follows:
wherein the content of the first and second substances,for material pointThe amount of material lost per unit time,first fingerAnd (4) reserving the materials before scheduling in each scheduling period.
The material gap of each material point when the current scheduling period is finished can be calculated by a formula:either the first or the second substrate is, alternatively,。
as shown in fig. 2, when a cycle is finished, calculating the consumption of periodic materials, and updating the service state of the virtual node according to the preset cycle interval and the material consumption speed, where updating the service state of the virtual node according to the preset cycle interval and the material consumption speed includes:
calculating the number of virtual nodes to be consumed according to the material consumption speed in the preset period interval, and setting the service state of the part of virtual nodes as。
Calculating the number of virtual nodes to be consumed according to the material consumption speed in the preset period interval, and setting the service state of the part of virtual nodes asWherein, in the step (A),indicating an unserviceable condition. The calculation formula for calculating the number of the virtual nodes of the loss according to the material consumption speed is as follows:i.e. to point the materialsAmount of material lost per unit timeAt a predetermined periodic intervalDivided by the capacity of a single virtual nodeAnd rounding up to obtain the number of the lost virtual nodes. Resetting the service state of the partially lost virtual node, i.e. setting the service state of the partially lost virtual node to。
And 5: order toIf, ifThen go back to execute the step 2, ifIf so, the dispatching is finished and a complete emergency plan can be output.
The invention couples a vehicle path problem model and a periodic material loss model: the method comprises the steps of considering accumulated space-time risks caused by inventory gap proportion and period intervals, converting the accumulated space-time risks into a reward collection problem, considering vehicle capacity constraints in demand splitting and actual logistics transportation in a scheduling scheme, and further constructing a multi-period vehicle path problem model considering reward collection, division delivery and capacity constraints under different risk estimation so as to provide a multi-target multi-period material scheduling vehicle path combination scheme for minimizing gap risks and logistics costs. Specifically, the method not only focuses on material sources and destinations, but also generates vehicle use, station access sequence and the like on the logistics scheme execution level, so that the optimization result has more actual reference value, and the utilization efficiency of transportation resources is improved; the invention divides the material points into the virtual node sets according to the capacity so as to split the requirements of the material points, thereby improving the full load rate of vehicles and the utilization efficiency of transportation resources; the invention considers the periodic initial gap risk in the multi-period vehicle path model by utilizing the reward collection mechanism, in the reward collection model, the vehicle does not need to visit all demand points any more, but encourages the vehicle to visit the distribution points with higher priority preferentially through a certain reward mechanism, and under the condition that the transportation resources are limited in the actual emergency material scheduling scene, the material scheduling scheme can preferentially ensure the material supply of the region with higher potential risk so as to reduce the global loss.
Optionally, a gap material risk coefficient is presetAnd periodic intervalThe value ranges of (1) are respectively combined by different parameters (gap material risk coefficient)And periodic intervalThe combination of the vehicle route schemes and the corresponding transportation cost and risk cost under different parameter combinations are obtained by executing the steps 1-5, the transportation cost and the risk cost of all the emergency material scheduling schemes are normalized and then summed by equal weight (or multi-target weight is defined according to requirements) to obtain dimensionless comprehensive cost, the multi-cycle vehicle route scheme with the lowest comprehensive cost and the corresponding optimal parameter combination are determined, and the multi-cycle vehicle route scheme with the lowest comprehensive cost is used as the optimal scheme for the multi-cycle emergency material scheduling. Referring to fig. 16, a multidimensional space diagram of the aggregate costs at different estimated risk factors and preset period intervals is shown, based on which the parameter combination with the lowest aggregate cost can be determined. FIG. 17 shows the variation of the logistics cost with the estimated risk factor under the premise of a certain preset period interval, as can be seen from FIG. 17, when the period interval is large, the estimated risk factorThe influence on the logistics cost is not obvious, and when the period interval is small, an excessively high risk coefficient can bring higher logistics cost, such asIn time, the logistics cost is not basically influenced by the estimated risk coefficient,in time, the logistics cost is greatly influenced by the estimated risk coefficient, and the estimated risk coefficient is too highWhich can result in excessive logistical costs. FIG. 18 shows the variation of the logistics cost with the predetermined period interval under the premise that the estimated risk factor is constant, as can be seen from FIG. 18, the estimated risk factorWhen the value is larger, the larger period interval brings lower logistics cost, and the estimated risk coefficientWhen smaller, the effect of the periodic intervals on logistics costs is insignificant, e.g. whenThe logistics cost is very little affected by the preset period interval. FIG. 19 is a diagram showing the variation of the gap risk of the material with the estimated risk factor under the premise of a certain preset period interval, as shown in FIG. 19, when the period interval is low, the estimated risk factorHas great influence on the risk of the material gap and estimates the risk coefficientThe elevation can reduce the risk of material gaps (e.g.Time, estimated risk factorThe risk of material gap is greatly reduced due to rising), and when the period interval is larger, the estimated risk coefficientThe risk of material gaps is not significantly affected, for example, whenWhen is atWhen the risk of the gap of the material is less than a certain value, the influence of the estimated risk coefficient is greatWhen the risk of the material gap is larger than a certain value, the risk of the material gap is not influenced by the estimated risk coefficient any more; when in useAnd meanwhile, the risk of the material gap is not influenced by the estimated risk coefficient. Fig. 20 shows the variation of the gap risk of the material with the predetermined period interval under the premise that the estimated risk factor is constant, the lower the estimated risk factor is, the stronger the monotonicity of the gap risk of the material with respect to the period interval is, the lower the estimated risk factor is, the larger the corresponding minimum gap risk of the material is, for example,andcompared with the prior art, the gap risk of the materials is more monotonous relative to the periodic interval, and the corresponding minimum gap risk of the materials is less.
The invention provides a combined optimization solving mechanism of multi-period multi-risk estimation coefficients, all optimal schemes in a designated value range interval are solved through parallel computing, and the scheme with the lowest comprehensive cost is selected for reference.
To facilitate understanding, a practical case is given, and fig. 3 to 11 show the risk coefficients in sequencePeriodic interval ofUnder the condition of the reaction, the reaction kettle is used for heating,the total of 9 periods of the material dispatching vehicle path scheme. The numerical value pairs of the nodes in the graph respectively represent the material point number and the residual material proportion of the material point after the current logistics scheme is executed, and different line types represent different vehicle paths. It can be observed that in this case, the material scheduling is performed only in the periods 0, 1 and 8, while the material scheduling is not performed in the periods 2 to 7, and the remaining material proportion of each material point is continuously decreased. Since the remaining material reserve at the material points will be consumed with the cycle iteration, as shown in fig. 10, the 8 th cycle estimates that the material remaining at the material point 1 (14%) is not enough to be supported to the end of the cycle, and the 9 th cycle immediately supplements each material point (as shown in fig. 11).
Step of timeAs Z axis, for complete emergency plansThe material scheduling scheme is visualized, and the effect is shown in fig. 12. It can be observed that after a certain number of iterations, a period is formed every 7 unit time steps, which indicates that the multi-period emergency plan generated by the invention forms a stable scheduling mode under the current parameter setting.
The logistics cost and the inventory gap risk of each period of the scheme are counted to obtain figures 13 to 15, wherein the figure 13 shows the estimated risk coefficientPreset periodic intervalLogistics cost and inventory gap risk, fig. 14 shows the estimated risk factorsPreset periodic intervalLogistics cost and inventory gap risk, fig. 15 shows the estimated risk factorPreset periodic intervalLogistics costs and inventory gap risks. The white bar represents logistics cost at different time steps and the grey represents inventory gap risk at different time steps.
In one embodiment, the device for multi-cycle split distribution of emergency materials based on inventory gap risk comprises a computer readable storage medium storing a computer program and a processor, wherein the computer program is read by the processor and runs to implement the method for multi-cycle split distribution of emergency materials based on inventory gap risk. Compared with the prior art, the beneficial effects of the emergency material multi-period segmentation and distribution device based on the inventory gap risk are consistent with those of the emergency material multi-period segmentation and distribution method based on the inventory gap risk, and the description is omitted here.
In one embodiment, the present invention provides a computer-readable storage medium, which stores a computer program, and when the computer program is read and executed by a processor, the method for multi-cycle segmentation and distribution of emergency materials based on risk of inventory gaps as described above is implemented.
Compared with the prior art, the beneficial effects of the computer-readable storage medium of the invention are consistent with the above-mentioned emergency material multi-period segmentation distribution method based on the risk of the inventory gap, and are not repeated herein.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.
Claims (10)
1. An emergency material multi-cycle segmentation distribution method based on inventory gap risks is characterized by comprising the following steps:
step 1: dividing the total time length of the emergency plan into a plurality of dispatching cycles at preset cycle intervals, using i to represent the serial numbers of the dispatching cycles,(ii) a For any material point, dividing the material point into material points according to capacityA set of virtual nodes that are equal in size,;
step 2: solving the multi-cycle vehicle path model to obtain the firstA material scheduling scheme for each scheduling cycle is performedA material scheduling scheme for each scheduling period;
and step 3: after the execution is finishedAfter the material scheduling scheme of each scheduling period, updating the reserve quantity of material points, and updating the service state of the virtual nodes according to the material scheduling scheme;
and 4, step 4: calculating material gaps of each material point at the end of the current scheduling period according to the preset period interval and the material consumption speed, updating a virtual node service state according to the preset period interval and the material consumption speed, and updating a target function of the multi-period vehicle path model;
2. The stock gap risk based emergency material multi-cycle segmentation distribution method of claim 1, wherein the objective function of the multi-cycle vehicle path model is as follows:
wherein the content of the first and second substances,for a positive number greater than the preset value,a fleet set is represented as a set of vehicles,represents a vehicle number, 0 represents a distribution center,a set of virtual nodes is represented that is,、each of which represents a virtual node,representative arcThe driving distance of the vehicle is set to be,is shown asThe decision variables of the cycle are varied in such a way that,indicating the value of the access reward,the status of the service is indicated,representing virtual nodesThe corresponding inventory gap space-time risk,indicating that the preset period interval is set to be,representing virtual nodesCorresponding material pointAt said predetermined periodic intervalsThe integral of the inner one of the two,for material pointThe size of the (c) is (d),for material pointThe risk factor of inventory gaps of (a),for material pointThe number of the capacity is divided into parts,first fingerExecution of a periodic scheduling schemeThe line time.
3. The stock gap risk based emergency material multi-cycle segmentation distribution method according to claim 2, wherein the updating of the virtual node service state according to the material scheduling scheme comprises:
4. The stock gap risk based emergency material multi-cycle segmentation distribution method as claimed in claim 3, wherein the preset number is:
5. The multi-cycle split distribution method for emergency materials based on inventory gap risk as claimed in claim 4,
6. The stock gap risk based emergency material multi-cycle segmentation distribution method as claimed in any one of claims 2 to 5, wherein the updating of the virtual node service state according to the preset cycle interval and the material consumption speed comprises:
7. The stock gap risk based emergency material multi-cycle segmentation distribution method as claimed in any one of claims 2 to 5, wherein the constraint conditions of the multi-cycle vehicle path model are as follows:
wherein the decision variablesRepresentative vehicleWhether or not to pass through arc0 represents in distributionThe heart is provided with a plurality of heart-shaped grooves,is a set of nodes to be served,is a collection of a fleet of vehicles,which represents the number of the vehicle,is a node to be served by a node,representsThe amount of demand for the point(s),is a collection of network arcs and is,represents a segment of an arc in the network,representsThe arc-out of the point is realized,representsThe arc-in of the point is formed,set of representative material pointsAll of the arc-out points of (c),indicating vehiclesWhether or not to pass through arc。
8. The stock gap risk based multi-cycle split distribution method for emergency materials according to claim 1, further comprising:
presetting a value range of a stock gap risk coefficient and the preset period interval;
respectively executing the steps 1-5 according to parameter combinations composed of different inventory gap risk coefficients and preset period intervals to obtain material scheduling schemes under different parameter combinations and corresponding transportation cost and risk cost;
and normalizing the transportation cost and the risk cost of all the material scheduling schemes, calculating the weighted sum to obtain dimensionless comprehensive cost, determining the material scheduling scheme with the lowest comprehensive cost and the corresponding optimal parameter combination thereof, and taking the material scheduling scheme with the lowest comprehensive cost as the optimal scheme for multi-period emergency material scheduling.
9. An emergency material multi-cycle segmentation distribution device based on inventory gap risk, which comprises a computer readable storage medium storing a computer program and a processor, wherein the computer program is read and executed by the processor to realize the emergency material multi-cycle segmentation distribution method based on inventory gap risk according to any one of claims 1 to 8.
10. A computer-readable storage medium, wherein a computer program is stored, and when the computer program is read and executed by a processor, the method for multi-cycle split distribution of emergency materials based on risk of inventory gaps according to any one of claims 1 to 8 is implemented.
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