深圳大学管理学院：《运筹学》课程教学资源（PPT课件讲稿）专题（计算机仿真）分布仿真模型 Distributed Simulation Modeling of Warehousing Operations

Distributed Simulation Modeling of Warehousing Operations M. Zhou, Y.J. Son, C. Chen, and Q. Zhang Center for System Modeling and simulation Indiana State University Terre haute. Indiana 47809

Distributed Simulation Modeling of Warehousing Operations M. Zhou, Y. J. Son, C. Chen, and Q. Zhang Center for System Modeling and Simulation Indiana State University Terre Haute, Indiana 47809

Intro to distributed simulation What is adistributed sinu lation?? A super simulation process that contains multiple sub- simulation programs that are independently executing and interacting with each other, and coordinated through the super-simulation process Why distributed simu lation? Composite and complex nature of real world Systems Needs for synchronizing multiple asynchronized software processes/systems Needs for simulating geographically distanced systems(e.g. military applications) Applications

Intro to distributed simulation ◼ What is a “distributed simulation”? A super￾simulation process that contains multiple sub￾simulation programs that are independently executing and interacting with each other, and coordinated through the super-simulation process ◼ Why distributed simulation? – Composite and complex nature of real world systems – Needs for synchronizing multiple asynchronized software processes/systems – Needs for simulating geographically distanced systems (e.g. military applications) – Applications

Intro to Warehousing/DC operations Key operational processes in warehouse- based Distribution Centers(DCs) Truck-docking process: activities to prepare trucks for loading or offloading at a DC In-bound process: receiving operations, e.g offloading, inspecting, sorting and storing Out-bound process: shipping operations, e.g picking, staging, sorting, packing, and loading Cross-docking: breaking bulk, mixing and directly shipping without storage

Intro to Warehousing/DC operations ◼ Key operational processes in warehouse￾based Distribution Centers (DCs): – Truck-docking process: activities to prepare trucks for loading or offloading at a DC – In-bound process: receiving operations, e.g. offloading, inspecting, sorting and storing. – Out-bound process: shipping operations, e.g. picking, staging, sorting, packing, and loading – Cross-docking: breaking bulk, mixing and directly shipping without storage

Intro to warehousing processes a In real world these processes are considered running separately or independently The activities/operations in the processes are inter-related in terms of resource(e.g, sharing the same crew of labor and equipment)and flow logic(e.g. truck docking affects both inbound and outbound operation, inventory management also affects inbound (replenishment)and outbound flows)

Intro to warehousing processes ◼ In real world these processes are considered running separately or “independently” ◼ The activities/operations in the processes are inter-related in terms of resource (e.g. sharing the same crew of labor and equipment) and flow logic (e.g. truck docking affects both inbound and outbound operation, inventory management also affects inbound (replenishment) and outbound flows)

Exemplary interactions Inbound process assigns resource (e.g. an offloading crew that involves labor and equipment) and starts sorting and put-away storage operation when truck- docking process seizes and finishes connecting to a dock-door When Inbound process finishes off-loading activity the truck will release the door and leave the yard(a waiting or staging space Outbound process initializes picking-sorting-packing jobs as a result of order-processing(an activity of inventory management) Interactions are triggered by the events that are the consequences of the activities belonging to different processes

Exemplary interactions ➢ Inbound process assigns resource (e.g. an offloading crew that involves labor and equipment) and starts sorting and put-away storage operation when truck￾docking process seizes and finishes connecting to a dock-door ➢ When Inbound process finishes off-loading activity, the truck will release the door and leave the yard (a waiting or staging space) ➢ Outbound process initializes picking-sorting-packing jobs as a result of order-processing (an activity of inventory management) ➢ Interactions are triggered by the events that are the consequences of the activities belonging to different processes

Simulation of subsystems and overall system To reduce modeling complexity, we usually build simulation models separately for each subsystem to evaluate its performance with assumptions(and constraints) about the interfaces between the subsystems Subsystems usually assume different forms of entities defined to satisfy the different objectives of analysis the objectives for analyzing that subsystem

Simulation of subsystems and overall system ◼ To reduce modeling complexity, we usually build simulation models separately for each subsystem to evaluate its performance with assumptions (and constraints) about the interfaces between the subsystems ◼ Subsystems usually assume different “forms” of entities defined to satisfy the different objectives of analysis__ the objectives for analyzing that subsystem

An example In a CD/DVD distribution process, three subsystems, a location-based picking process, an automatic sorting proces and a wrapping/packing/shipping process are running separately but coordinated through the control of a sequence of events Location-based Automatic Picking process sorting process Wrapping and shipping process Solid arrows: material flow: dashed arrows. information flow

An example … ◼ In a CD/DVD distribution process, three subsystems, a location-based picking process, an automatic sorting process, and a wrapping/packing/shipping process are running separately but coordinated through the control of a sequence of events Location-based Picking process Automatic sorting process Wrapping and shipping process Solid arrows: material flow; dashed arrows: information flow

Distributed simulation a In order to effectively and efficiently simulate the overall performance of a DC, we need to integrate the individual simulation models developed for the subsystems (legacy systems), i.e. coordinate their executions in a distributed environment to accomplish the analysis Distributed simulation provides a technology that enables us to integrate and coordinate the simulation models developed for each subsystems namely, truck-docking, inbound, and outbound process so that the per formance of the overall system(a distribution center) can be more realistically and accurately described and evaluated through simulation

Distributed simulation ◼ In order to effectively and efficiently simulate the overall performance of a DC, we need to integrate the individual simulation models developed for the subsystems (legacy systems), i.e. coordinate their executions in a distributed environment to accomplish the analysis ◼ Distributed simulation provides a technology that enables us to integrate and coordinate the simulation models developed for each subsystems, namely, truck-docking, inbound, and outbound process so that the performance of the overall system (a distribution center) can be more realistically and accurately described and evaluated through simulation

a distributed simulation environment Architectural components Legacy models/systems(HLA based federates) Coordination/manager model(hLa based Federation manager Data repository Interfaces/adapters(transmission, receipt and internal updates to all FOm objects used by a federate) Tools(e.g. output analysis) a Integration infrastructure/platform(e.g. RTI based on the hla standard

Architectural components: ◼ Legacy models/systems (HLA based federates) ◼ Coordination/manager model (HLA based Federation manager) ◼ Data repository ◼ Interfaces/adapters (transmission, receipt and internal updates to all FOM objects used by a federate) ◼ Tools (e.g. output analysis) ◼ Integration infrastructure/platform (e.g. RTI based on the HLA standard) A distributed simulation environment

a distributed simulation environment Data integration Communications between subsystems are realized via messages that trigger the events and transfer common data structures MessageName Sender, Receiver, List FOM Object Attributes For example Request IB TD: IB,(I Load Type, T. SkuList T. SkuOty, T Requested Task Type, . 7

A distributed simulation environment ◼ Data integration - Communications between subsystems are realized via messages that trigger the events and transfer common data structures MessageName {Sender; Receiver; List_FOM Object Attributes}; For example: Request_IB {TD; IB; (T.LoadType, T.SkuList, T.SkuQty; T.RequestedTaskType, …)}