Comprehensive scheduling method considering on-time completion and energy consumption

Abstract

A comprehensive scheduling algorithm considering on-time completion and energy consumption, the method of the present invention comprises: adopting an energy consumption priority strategy to determine the scheduling order of the process; adopting an equipment time consumption allocation strategy to determine the processing equipment for non-subtree key energy consumption processes; adopting a process time consumption balancing strategy to determine the initial processing equipment for subtree key energy consumption processes; adopting a process equipment adjustment strategy to re-determine the process processing equipment when the subtree key energy consumption process does not meet the time constraint after scheduling on the initial processing equipment; and adopting a delivery date backtracking adjustment strategy to make final equipment adjustments for the processes that do not meet the on-time completion requirement.

Description

Technical Field

[0001] The invention relates to a comprehensive scheduling method considering on-time completion and energy consumption. Background Art

[0002] At present, the comprehensive scheduling method based on flexible equipment processing only considers whether the product can be completed on time due to processing on different equipment, but does not consider the energy consumption in the production process.

[0003] In actual workshop scheduling, it is necessary to design a comprehensive scheduling method that takes into account both on-time completion and energy consumption. While ensuring that products are completed on time, it is necessary to reasonably configure processing equipment, optimize equipment operation plans, and minimize energy consumption. Summary of the invention

[0004] The purpose of the present invention is to provide a comprehensive scheduling method that takes on-time completion and energy consumption into consideration. Aiming at the problem that on-time completion and energy consumption are not taken into consideration in the existing comprehensive scheduling methods, a comprehensive scheduling method that takes on-time completion and energy consumption into consideration is proposed, in which an energy consumption priority strategy is adopted to determine the scheduling order of the processes; for non-subtree key energy consumption processes, an equipment time consumption allocation strategy is adopted to determine the processing equipment; for subtree key energy consumption processes, a process time consumption balancing strategy is adopted to determine the initial processing equipment; when the subtree key energy consumption process does not meet the time constraint after being scheduled on the initial processing equipment, a process equipment adjustment strategy is adopted to re-determine the process processing equipment; and a delivery date backtracking adjustment strategy is adopted to make final equipment adjustments for the processes that do not meet the on-time completion requirement.

[0005] The energy consumption priority strategy is to sort the scheduling order of the processes to facilitate the arrangement of processing equipment for subsequent processes. Advantages are analyzed as follows: the hierarchical priority strategy can be used to process the leaf nodes of the subtree with more layers as soon as possible, and the parallel processing time of the processes on the remaining paths can be increased, thereby reducing the total time. Prioritizing the processing of critical paths can control the total time; the short-time strategy can advance the processing time of subsequent processes; and the low-energy consumption strategy is used to resolve conflicts.

[0006] The process time consumption balancing strategy is to preliminarily select the processing equipment for the key energy consumption process of the subtree to reduce time and energy consumption. Advantage analysis: Since the process on the key energy consumption path of the subtree determines the energy consumption and time of the entire process, the processing machine is determined first, and based on the relevant calculation results, the dual optimal solution of time and energy consumption is achieved in the selectable equipment concentration, which can reduce the time and energy consumption on the key energy consumption path of the subtree, thereby reducing the total time and total energy consumption.

[0007] The equipment time consumption allocation strategy is to select equipment for non-subtree key energy-consuming processes to ensure that the processing time, equipment load level and energy consumption are acceptable. Advantage analysis: It not only considers the impact of time and machine load energy consumption on the entire processing, but also takes into account the parallel effect of each processing equipment. Under the premise of not affecting the scheduling time of the subtree key energy-consuming processes, the equipment screening strategy can be flexibly selected according to the number of machines and equipment.

[0008] The equipment adjustment strategy is to optimize the pre-selection situation and reduce the total energy consumption on the basis of ensuring the delivery time. Advantage analysis: the key energy-consuming processes of the subtree that meet the conditions are adjusted, which not only takes into account the actual production scheduling situation to enable early processing, but also ensures the parallelism of processing and the utilization rate of the machine.

[0009] The delivery date backtracking adjustment strategy is to ensure that the product is completed on time. Advantage analysis: According to the delivery date, root node, and subtree root node, the subtree power delivery date range is limited to ensure the flexibility and timeliness of processing and production.

[0010] The above purpose is achieved through the following technical solutions:

[0011] A comprehensive scheduling method considering on-time completion and energy consumption, the method mainly includes the following steps: using energy consumption priority strategy to determine the scheduling order of the process; for non-subtree key energy consumption processes, using equipment time consumption allocation strategy to determine the processing equipment; for subtree key energy consumption processes, using process time consumption balance strategy to determine the initial processing equipment; when the subtree key energy consumption process does not meet the time constraint after scheduling on the initial processing equipment, using process equipment adjustment strategy to re-determine the process processing equipment; using delivery date backtracking adjustment strategy to make final equipment adjustments for processes that do not meet on-time completion; the comprehensive scheduling method considering on-time completion and energy consumption, the specific implementation steps of the scheduling method are as follows:

[0012] Step 1 calculates the process processing energy consumption, virtual energy consumption, equipment startup energy consumption, average processing time, subtree power delivery period and period radius;

[0013] Step 2: Split the process tree into subtrees, calculate the key energy consumption paths of the subtrees, and sort them in descending order.

[0014] Step 3: Use the process time consumption balance strategy to select the processing equipment of the key energy consumption process of the subtree, and determine the selection order of the process processing according to the energy consumption priority strategy;

[0015] Step 4 determines whether the key energy-consuming process of the subtree meets the equipment process adjustment strategy. If yes, execute step 5; otherwise, execute step 6;

[0016] Step 5: Use the device time consumption allocation strategy to select devices;

[0017] Step 6: Schedule the root node. As long as it meets the delivery period of the subtree power, select the equipment with the lowest processing energy consumption for processing;

[0018] Step 7 determines whether the schedulable process set is empty. If so, proceed to step 8; otherwise, proceed to step 4;

[0019] Step 8 determines whether the no-load energy consumption and no-load time of the machine with idle time are both greater than the startup energy consumption and startup time respectively. If they are satisfied, the device restarts; otherwise, no-load is selected; the initial startup time of the machine is adjusted; the initial startup time of the machine is adjusted;

[0020] Step 9: After product processing is completed, the Gantt chart of product scheduling results is output.

[0021] The comprehensive scheduling method considering on-time completion and energy consumption, the energy consumption priority strategy, first sets the priority for the process, the higher the priority, the earlier it is scheduled; when the priorities of the processes are the same, the processes with longer subtree critical energy consumption paths are scheduled first, and the non-subtree critical energy consumption processes with shorter average processing time are selected for scheduling; when the lengths of the subtree critical energy consumption paths are the same or the average processing time is the same, the processes with lower virtual energy consumption are selected for priority scheduling.

[0022] The comprehensive scheduling method considering on-time completion and energy consumption and the process time consumption balancing strategy respectively calculate the weights of the optional equipment set, select the equipment with the smallest weight for processing, and preliminarily determine the processing equipment for the key energy-consuming processes of the subtree.

[0023] The comprehensive scheduling method that considers on-time completion and energy consumption, and the equipment time consumption allocation strategy, determine the processing equipment of non-subtree key energy-consuming processes by deleting processing equipment whose concentrated processing time and processing energy consumption are greater than the average processing time and virtual energy consumption, and flexibly selecting different screening schemes according to the number of remaining equipment.

[0024] The comprehensive scheduling method that considers on-time completion and energy consumption, and the equipment adjustment strategy, re-determine the process processing equipment for the subtree key energy-consuming processes that meet the requirement that the start processing time on this equipment is greater than or equal to the maximum completion time on all its machines, so as to ensure processing parallelism and machine utilization.

[0025] The comprehensive scheduling method considering on-time completion and energy consumption and the delivery date retrospective adjustment strategy make final equipment adjustments for processes that do not meet on-time completion requirements; the subtree power delivery date range is limited based on the delivery date, root node, and subtree root node to ensure the flexibility and timeliness of processing and production.

[0026] Beneficial effects:

[0027] 1. The present invention effectively balances the time and energy consumption issues of key energy-consuming processes through a process time consumption balancing strategy, and provides a basis for the subsequent screening of the maximum completion time constraint equipment set for non-subtree key energy-consuming processes.

[0028] The present invention adopts the equipment time consumption allocation strategy to screen relatively good equipment processing strategies, and finely divides different scheduling strategy selections according to the number of equipment, making the selection of processing machines for the process more flexible.

[0029] The present invention uses a delivery date backtracking adjustment strategy to adjust the process using the delivery date constraint, which not only takes into account the reasonable allocation of energy consumption and equipment time consumption, but also flexibly adjusts the process by setting the delivery date range in layers to achieve an optimization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Attached Figure 1 It is a process tree illustration of the present invention.

[0031] Attached Figure 2 It is the device related information of the present invention.

[0032] Attached Figure 3 The present invention is based on the attached Figure 2 The calculation results of relevant information.

[0033] Attached Figure 4 The present invention is to Figure 1 The processing equipment selection results of the process tree shown.

[0034] Attached Figure 5 The present invention is to Figure 1 Gantt chart of the scheduling results of the process tree is shown. DETAILED DESCRIPTION

[0035] Embodiment 1:

[0036] A comprehensive scheduling method considering on-time completion and energy consumption is characterized by: first determining the scheduling order of each process; using different strategies to screen the equipment set for the subtree key energy consumption process and the non-subtree key energy consumption process; when the subtree key energy consumption process does not meet the time constraint after scheduling on the initial processing equipment, using the whole strategy to re-determine the process processing equipment; and rescheduling the process that does not meet the delivery period.

[0037] Embodiment 2:

[0038] The above-mentioned flexible comprehensive scheduling method for workshop 2 with early migration of the buffer process, the specific implementation steps of the scheduling method are as follows:

[0039] Step 1 calculates the process processing energy consumption, virtual energy consumption, equipment startup energy consumption, average processing time, subtree power delivery period and period radius;

[0040] Step 2: Split the process tree into subtrees, calculate the key energy consumption paths of the subtrees, and sort them in descending order.

[0041] Step 3: Use the process time consumption balance strategy to select the processing equipment of the key energy consumption process of the subtree, and determine the selection order of the process processing according to the energy consumption priority strategy;

[0042] Step 4 determines whether the key energy-consuming process of the subtree meets the equipment process adjustment strategy. If yes, execute step 5;

[0043] Step 5: Use the device time consumption allocation strategy to select devices;

[0044] Step 6: Schedule the root node. As long as it meets the delivery period of the subtree power, select the equipment with the lowest processing energy consumption for processing;

[0045] Step 7 determines whether the schedulable process set is empty. If so, proceed to step 8; otherwise, proceed to step 4; otherwise, proceed to step 6;

[0046] Step 8 determines whether the no-load energy consumption and no-load time of the machine with idle time are both greater than the startup energy consumption and startup time respectively. If they are satisfied, the device restarts; otherwise, no-load is selected; the initial startup time of the machine is adjusted; and the initial startup time of the machine is adjusted;

[0047] Step 9: After product processing is completed, the Gantt chart of product scheduling results is output.

[0048] Embodiment 3:

[0049] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption, the energy consumption priority strategy, first sets the priority for the process, the higher the priority, the earlier it is scheduled; when the priorities of the processes are the same, the processes with longer subtree critical energy consumption paths are scheduled first, and the non-subtree critical energy consumption processes with shorter average processing time are selected for scheduling; when the lengths of the subtree critical energy consumption paths are the same or the average processing time is the same, the processes with lower virtual energy consumption are selected for priority scheduling.

[0050] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption and the process time consumption balancing strategy respectively calculate the weights of the optional equipment set, select the equipment with the smallest weight for processing, and preliminarily determine the processing equipment of the key energy-consuming process of the subtree.

[0051] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption, and the equipment time consumption allocation strategy, determine the processing equipment of non-subtree key energy-consuming processes by deleting the processing equipment whose concentrated processing time and processing energy consumption are greater than the average processing time and virtual energy consumption, and flexibly selecting different screening schemes according to the number of remaining equipment.

[0052] The comprehensive scheduling method that considers on-time completion and energy consumption, and the equipment adjustment strategy, re-determine the process processing equipment for the subtree key energy-consuming processes that meet the requirement that the start processing time on this equipment is greater than or equal to the maximum completion time on all its machines, so as to ensure processing parallelism and machine utilization.

[0053] The delivery date retrospective adjustment strategy is to make final equipment adjustments for processes that fail to meet the deadline; the subtree power delivery date range is limited according to the delivery date, root node, and subtree root node to ensure the flexibility and timeliness of processing and production.

[0054] Embodiment 4:

[0055] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption, the energy consumption priority strategy, first sets the priority order for the process, assuming that the processing tree has a total of c layers, then the priority of the root node process is set to 1, and the priority of its left and right child node processes is set to 2, and so on, and it is stipulated that the larger the number, the higher the priority, and the earlier the process is selected for scheduling; when the priorities are the same, the processes with long subtree key energy consumption paths are scheduled first, when the energy consumption path lengths are the same, the processes with small average processing time are selected for addition, and the non-subtree key energy consumption processes with small average processing time are selected for processing; finally, when the subtree key energy consumption path lengths are the same or the average processing time is the same, the processes with low virtual energy consumption are scheduled first.

[0056] Embodiment 5:

[0057] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption, the process time consumption balancing strategy, because the process on the critical energy consumption path of the subtree determines the energy consumption and time of the entire process, so first determine its processing machine; in order to achieve the dual optimal solution of time and energy consumption in the selectable equipment set, it is measured by W, and its calculation formula is:

[0058] W=a1(Tij / t)+a2(Eij / e)

[0059] Among them, a1 and a2 are the weight coefficients of processing time and energy consumption during processing respectively. The specific weight coefficients need to be analyzed and determined according to the purpose. t and e are unit time and unit energy consumption respectively. We hope to choose equipment with low energy consumption and short processing time for processing, so the objective function of the equipment is selected as min(W).

[0060] Embodiment 6:

[0061] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption, the equipment time consumption allocation strategy described, first deletes the processing equipment whose processing time and processing energy consumption are greater than the average processing time and virtual energy consumption, and observes the number of equipment m in the optional equipment set: if m=1, then this equipment is selected for processing; if m=2, when their completion times all meet the delivery date or the maximum completion time of the key energy-consuming process of this layer, if the processing time and energy consumption of one of the equipment are less than that of the other equipment, then the former is selected; otherwise, the equipment with a smaller ratio of maximum completion time to processing energy consumption is selected for processing; if m≥3, the load time consumption factor is calculated:

[0062] X=n1(|C-Cave| / Cmax-Cmin)+n2(|W-Wave| / Wmax-Wmin)+n3(|E-Eave| / Emax-Emin)

[0063] Among them, C, W, and E are the completion time of the process on this equipment, the existing load energy consumption of the machine, and the process processing energy consumption, respectively. *ave represents the average value of the process and equipment parameters, *max-*min is the range, and min(X) is the objective function.

[0064] Embodiment 7:

[0065] The above-mentioned comprehensive scheduling method that considers on-time completion and energy consumption, and the equipment adjustment strategy, for the subtree key energy-consuming processes that meet the requirement that the start processing time of the process on this equipment is greater than or equal to the maximum completion time on all its machines, it is necessary to delete this equipment information in the optional equipment set, update its equipment set and re-screen it using the equipment time consumption allocation strategy.

[0066] Embodiment 8:

[0067] The above-mentioned comprehensive scheduling method considering on-time completion and energy consumption, the delivery date backtracking adjustment strategy, limits the production time of the preceding process of the root node according to the delivery date. If the delivery date is m, this tree has n layers, and Cn-k+1 is the average processing time of the kth layer. Since k∈[n-2,n-1,n], which corresponds to the calculation of the root node completion time limit, the subtree root node completion time limit and the subtree root node processing time limit respectively, the delivery time of the kth layer is called the subtree power delivery time, and its calculation formula is: [Σkn-1[m-Cn-k+1]-Cn-k], the period radius is Cn-kC(nk)min (when k=n, the period radius is r0), where [*] is the integer function; the subtree power delivery time limit is: [Σkn-1[m-Cn-k+1]-Cn-k]+Cn-kC(nk)min; when the completion time of the process exceeds the subtree power delivery time limit, it is necessary to use the equipment time consumption allocation strategy to re-screen the equipment for the process.

[0068] Embodiment 9:

[0069] The above comprehensive scheduling method considering on-time completion and energy consumption is shown in the attached Figure 1 As shown in the figure, it is a process tree diagram of a multiple order product A. There are 24 processes in total and 6 processing equipment. Each process can be processed on different equipment. The detailed information of the process processing equipment is as follows. Figure 2 As shown, each machine can be switched on and off up to 2 times in a single processing operation, with a delivery period of 80.

[0070] The following will be combined with the attached Figure 1 The process tree diagram and attached Figure 2 The detailed information of the device is used to illustrate the specific execution process of this method.

[0071] Embodiment 10:

[0072] The above comprehensive scheduling method considering on-time completion and energy consumption will be used to schedule the following Figure 1 The process tree diagram in the figure is used to perform scheduling. The specific steps are as follows:

[0073] First, it is necessary to calculate the processing energy consumption, virtual energy consumption, equipment startup energy consumption and average processing time of each machine of the product. The results are shown in the attached Figure 3 shown.

[0074] The process tree of A is split into subtrees and arranged in descending order according to the key energy consumption paths on each subtree. The arrangement order is {(A1, A4, A8, A14, A21), (A2, A5, A9, A16, A22), (A6, A12, A19, A23)}; and the subtree key energy consumption path priority strategy is used to preliminarily determine the processing equipment set of the key energy consumption process as {(A1 / 6 / 16 / 1.5, A4 / 1 / 4 / 7, A8 / 4 / 9 / 2. 1, A14 / 4 / 10 / 2, A21 / 6 / 8 / 1), (A2 / 3 / 6 / 2.1, A5 / 4 / 7 / 2.1, A9 / 1 / 7 / 2.3, A165 / 10 / 3, A22 / 6 / 10 / 0.7), (A6 / 5 / 16 / 1.8, A12 / 1 / 7 / 2.8, A19 / 2 / 12 / 3.2, A23 / 2 / 6 / 2)}, where it means process number / processing equipment / processing time / average processing energy consumption.

[0075] Assuming that all equipment starts at time 0, the energy consumption priority strategy is used to sort the process selection: the processes at the same level give priority to scheduling the subtree critical path. For non-subtree critical energy consumption processes, the processes with short average processing time are prioritized. When the average processing times are the same, the processes with large virtual energy consumption are selected for scheduling. The final selectable process queue is: {(A1, A2, A3), (A4, A5, A6), (A8, A9, A12, A11, A10, A13, A7), (A14, A16, A19, A17, A20, A18, A15), (A21, A22, A23), A24}.

[0076] The equipment time consumption allocation strategy is used to screen the equipment for non-subtree key energy consumption processes, and the equipment adjustment strategy is used to adjust the equipment for processes that do not meet the conditions. The screening and adjustment results are as follows: Figure 4 shown.

[0077] Finally, the devices in idle time are restarted / idled. Since the idle energy consumption of the M2 device is greater than the restart energy consumption, and the idle time is greater than the device startup time, the device M2 is restarted during idle time. After calculation, the devices that need to be restarted are M2, M5, and M6, and the device that needs to be idle is M4. The initial startup time of M1 and M4 is adjusted to 16:00 and 7:00 respectively. After the product scheduling is completed, the Gantt chart is output, as shown in the attached figure. Figure 5 shown.

[0078] Embodiment 11:

[0079] The above comprehensive scheduling method considering on-time completion and energy consumption is compared with the following examples:

[0080] Since the comprehensive scheduling method considering on-time completion and energy consumption proposed in this invention has not been studied before, no suitable examples have been found for comparative analysis. Figure 1 The Gantt chart of Product A is shown in the attached Figure 5 It can be seen that the total processing time of product A is 63, which is less than the delivery period, and the energy consumption is 446.29. In addition, the parallelism, equipment load balancing, subtree power delivery period delivery restrictions and idle time energy consumption issues are fully considered in the scheduling process, and good scheduling results are achieved. This method solves the problem of flexible comprehensive scheduling of a single workshop to a certain extent.

[0081] Therefore, the scheduling method proposed in the present invention is to solve the problem of considering on-time completion and energy consumption in the comprehensive scheduling of a single workshop.

Claims

1. A comprehensive scheduling method considering on-time completion and energy consumption, characterized by The method mainly includes the following steps: using energy consumption priority strategy to determine the scheduling order of the process; using equipment time consumption allocation strategy to determine the processing equipment for non-subtree key energy consumption processes; using process time consumption balance strategy to determine the initial processing equipment for subtree key energy consumption processes; when the subtree key energy consumption process does not meet the time constraint after scheduling on the initial processing equipment, using process equipment adjustment strategy to re-determine the process processing equipment; using delivery date retrospective adjustment strategy to make final equipment adjustments for processes that do not meet the on-time completion time; the specific implementation steps of the scheduling method are as follows: Step 1: Calculate the process energy consumption, virtual energy consumption, equipment startup time, average processing time, subtree power delivery period and period radius, that is, the maximum minus the minimum average processing time of the kth layer of the subtree; Step 2: Split the process tree into subtree powers, that is, after removing the root node from the process tree, its child nodes become subtrees separately. The set of all subtrees in the tree is called subtree power. Calculate the subtree key energy consumption path, that is, the path with the largest sum of virtual energy consumption on a path from the root node to the leaf node in the subtree, and arrange them in descending order; Step 3: Use the process time consumption balance strategy to select the processing equipment for the key energy consumption process, and determine the scheduling order of the process according to the energy consumption priority strategy; Step 4 determines whether the key energy consumption process of the subtree meets the equipment process adjustment strategy. If yes, execute step 5; otherwise, execute step 6; Step 5: Use the device time consumption allocation strategy to select devices; Step 6: Schedule the root node. As long as it meets the delivery period of the subtree power, select the equipment with the minimum processing energy consumption for processing; Step 7 determines whether the schedulable process set is empty. If so, proceed to step 8. Otherwise, proceed to step 4. Step 8 determines whether the no-load energy consumption and no-load time of the machine with idle time are both greater than the startup energy consumption and startup time respectively. If they are satisfied, the device restarts. Otherwise, no-load is selected and the initial startup time of the machine is adjusted; Step 9: After product processing is completed, the Gantt chart of product scheduling results is output.

2. The comprehensive scheduling method considering on-time completion and energy consumption according to claim 1 is characterized by: The energy consumption critical priority strategy first sets the priority for the process. The higher the priority, the earlier it is scheduled, so that the leaf nodes of the subtree with more layers can be processed as soon as possible, and the parallel processing time of the processes on the remaining paths can be increased, thereby reducing the total time; in the same layer, the process priorities on the subtree critical energy consumption path are arranged in descending order of path length, which can control the total time and total energy consumption; the process priorities on the non-subtree critical path are arranged in ascending order of average processing time; low energy consumption is used to resolve priority setting conflicts in the same situation.

3. The comprehensive scheduling method considering on-time completion and energy consumption according to claim 1 is characterized by: The process time consumption balancing strategy described above is to preliminarily determine the processing equipment of the key energy consumption process of the subtree, select the processing equipment according to its processing time and processing energy consumption, and achieve a dual optimal solution of time and energy consumption in the selectable equipment set, which can reduce the time and energy consumption on the key energy consumption path of the subtree, thereby reducing the total time and total energy consumption.

4. The comprehensive scheduling method considering on-time completion and energy consumption according to claim 1 is characterized by: The device time consumption allocation strategy is used to select equipment for non-subtree key energy-consuming processes. It not only considers the impact of time and machine load energy consumption on the entire processing, but also considers the parallel effect of each processing equipment. Under the premise of not affecting the scheduling time of key energy-consuming processes, the equipment screening plan is flexibly selected according to the number of machines and equipment.

5. The comprehensive scheduling method considering on-time completion and energy consumption according to claim 1 is characterized by: The equipment process adjustment constraint strategy re-determines the process processing equipment for the subtree key energy-consuming process that satisfies the requirement that the start processing time on this equipment is greater than or equal to the maximum completion time on all its machines, so as to ensure the parallelism of processing and the utilization rate of the machine.

6. The comprehensive scheduling method considering on-time completion and energy consumption according to claim 1 is characterized by: The delivery date retrospective adjustment strategy is to make final equipment adjustments for processes that fail to meet the deadline; the subtree power delivery date range is limited according to the delivery date, root node, and subtree root node to ensure the flexibility and timeliness of processing and production.

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