Logistics simulation technology paper 1: Analysis and research of logistics system simulation technology Abstract Logistics system simulation is to simulate the logistics system with the help of computer technology, which is of great significance to logistics engineering projects. This paper mainly studies the basic theory of logistics system simulation technology, and puts forward the method of simulation using Flexsim software. This method can provide important decision-making basis for logistics system construction planning.
Logistics system simulation; Flexsim software
With the development of China's economy, the logistics industry is developing rapidly, and the construction of logistics projects all over the country is gradually carried out. However, in the investment and construction of the project, a series of rationality analysis problems have appeared, such as technical and economic feasibility and management methods. For example, whether the location of the logistics distribution center in the planning and construction process is appropriate, whether its capacity design, equipment configuration and site planning are reasonable, whether it can better simplify work and save cost and time, and whether the division of work areas such as tally, warehousing and sorting can be more convenient for the progress and management of various operations. If we judge these practical problems only by experience and feeling, we will inevitably ignore some aspects. Adjustment after completion will increase the project cost, delay the normal work and bring huge losses.
Logistics simulation technology is an application technology to simulate logistics system by using virtual reality method, computer technology, network technology and mathematical means. It needs the help of computer simulation technology to model and analyze the real logistics system, and obtain instantaneous simulation records of various dynamic activities and their processes through simulation experiments, so as to study the performance and output effect of the logistics system. The biggest advantage of logistics simulation technology is that the following objectives can be verified without installing actual equipment and implementing corresponding schemes: ① increasing the effect of new equipment on enterprises; ② Design the quality of new production line; ③ Compare the advantages and disadvantages of various design schemes and so on. This paper mainly studies the basic theory of logistics system simulation technology, and explains it through Flexsim simulation software.
1. Characteristics of logistics system simulation
The characteristics of logistics system simulation are mainly reflected in the following three aspects.
(1) Simulation of flow in logistics system: For various flows in logistics system, such as cargo flow, vehicle flow, information flow and capital flow, dynamic simulation can be used to describe the generation, flow, disappearance, accumulation and transformation of flows.
(2) Simulation of queuing in logistics system: A discrete system consisting of one or more service desks and customers waiting for service becomes a queuing system. Logistics system is a complex discrete event system. All kinds of facilities and equipment can be regarded as service desks, and all kinds of objects can be regarded as customers waiting for service.
(3) Factor simulation of logistics system organization: Logistics organization is realized through the participation of various personnel and equipment, which are all resources in the logistics system. Through different planning of various resources, the quality of logistics service and operational efficiency are also different. By using computer simulation technology to describe the behavior process of people and equipment, a better logistics system organization scheme can be obtained.
2. Advantages of logistics system simulation
When building a logistics system, because of the huge investment, there are certain investment risks, and the unreasonable places need to be transformed after completion, and the cost will be high. Using simulation technology to realize the running state of each module of logistics system, an economical and effective design scheme is obtained to adapt to development. Logistics system simulation technology mainly has the following advantages.
(1) Complex logistics system can be modeled by simulation; (2) The feasibility and efficiency of the new logistics system can be correctly judged by computer simulation without actual construction investment, and if the scheme is reasonable, the investment risk can be reduced; (3) Multiple schemes can be analyzed and compared, and the optimal scheme can be selected; (4) Adjust the objective function and constraint conditions through simulation, and optimize the scheme.
3. Steps of logistics system simulation
General steps of logistics system simulation: (1) Find out the problem and grasp the actual situation; (2) collecting and sorting out data; (3) Determine the interrelation among various factors; (4) building a simulation model; (5) determining model parameters; (6) Check the correctness of the model; (7) Operation and result analysis of the simulation model.
4.Flexsim simulation software
4. 1 Flexsim simulation software introduction
Flexsim is a commercial discrete event system simulation software produced by American Flexsim software production company. Flexsim adopts object-oriented technology and has three-dimensional display function. Modeling is fast and convenient, and the display ability is strong, especially suitable for manufacturing, distribution, transportation and other fields. Its main features include: (1) modeling based on object-oriented technology; (2) Excellent 3D graphic display function; (3) convenient modeling and debugging; (4) The expansibility of modeling is strong; (5) Good openness.
4.2 Modeling and simulation methods using Flexsim simulation software
(1) Set the model layout
The objects in the Flexsim object library can basically reflect the actual facilities. For example, the source of goods and the source of goods can be represented by generators and absorbers respectively, the processing operation can be represented by processors, and there are corresponding entities for shelves, conveyor belts and operators respectively. And according to the number and size of each entity, adjust it to a suitable position to make it consistent with the actual plan. When setting these parameters, it is necessary to set the parameters according to the specific object characteristics in order to simulate the display correctly.
(2) Definition? Flow?
According to the logical relationship between objects in the system, the corresponding ports are connected to construct the logical flow of the model.
Connections between entities can be connected through input/output (A) or intermediate endpoints (S). The operation flow should be consistent with the actual operation.
(3) Design of equipment parameters
According to the characteristics of the logistics system described by each object, the parameters of the object are set. Some commonly used simulation parameters in Flexsim mainly include:
① Generator parameters: temporary entities can be created according to arrival interval mode, arrival plan mode and arrival sequence mode. Through the generator, you can set the arrival type and arrival time distribution of goods.
② Processor parameters: Generally speaking, processor parameters are processor capacity, processing time, preset time, mean failure time and mean maintenance time.
③ Temporary storage area parameters: Temporary storage area parameters mainly include temporary storage area capacity, temporary storage area size and storage form of goods in the temporary storage area.
④ Shelf parameters: Shelf parameters mainly include shelf capacity, shelf quantity, floor number, column width, floor height, minimum residence time and stacking mode.
⑤ Transport parameters: Transport includes workers, transport forklifts, stackers, etc. The parameters mainly include loading time, unloading time, running speed, loading capacity, acceleration and transportation line design.
⑥ Temporary entity flow parameters: The temporary entity flow parameters determine how the entity sends the temporary entity downstream. These parameters mainly include the port of delivery, whether to use means of transport, whether to pull goods, conditions for pulling goods, priority and so on.
4.3 Analysis of compilation, operation and simulation results
After the model is established, the simulation model can be compiled and run. In order to reduce the error, the simulation results can be obtained by repeated operation or operation according to different setting conditions. Analyze the working conditions and efficiency of each object in the experiment, compare the results of different experiments, put forward improvement and optimization measures, and verify them again. Finally, the optimal scheme is obtained.
refer to
[1] Peng Yang, Wu. Modeling and Simulation of Logistics System [M]. Hangzhou: Zhejiang University Press, 2009.
[2] Zhou Xiangyang. One of the series lectures on logistics system simulation [J]. Logistics Technology and Equipment Edition, 20 10(3).
Xiao jiangbo. Simulation and Optimization of Distribution Center System Based on FLEXSIM [D]. Beijing: Beijing University of Posts and Telecommunications, 2008.
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