1、Inventory workforceInventory workforce这个模型是库存管理部门和劳动力供应链的相互作用,就像在John Sterman的“Business Dynamic”中描绘的一样。订货率可以使偶发的,或者可以人工调节的。第一步:创建新模型。(同模型Billing Department)第二步:创建库存的逻辑模型。1. 右键单击模型,选择new一个Active Object Class,命名为Inventory,如图1:图 12. 点击System Dynamics,想Inventory中拖入两个Stock Variable和三个Flow Aux Variable,分别
2、命名为Work_in_Process_Inventory、Inventory和Production_Start_Rate、Production_Rate、Shipment_Rate。双击Production_Start_Rate连接到Work_in_Process_Inventory,再点击Work_in_Process_Inventory再连接到Production_Rate,以此类推,最后连接到Shipment_Rate,其中Work_in_Process_Inventory和Inventory的Initial value分别是Desired_WIP和Desired_Inventory具体
3、布局如图2所示:图 23. 再从System Dynamics中拖入九个Flow Aux Variable,分别命名为Switch_for_Labor_in_Production、Productivity、Workweek、WIP_Adjustment_Time、Manufacturing_Cycle_Time、Inventory_Adjustment_Time、Minimum_Order_Processing_Time、Safety_Stock_Coverage、Time_to_Average_Order_Rate,并都选中Constant。在各自值的部分分别填写1、0.25、40、6、8、
4、12、2、2、8。4. 从System Dynamics拖入三个Flow Aux Variable,分别命名为Desired_Production_Start_Rate、Labor和Customer_Order_Rate,然后都选中public,Customer_Order_Rate再勾中External,分别右键单击三者,选择Create Shadow。5. 再从System Dynamics拖入十个Flow Aux Variable,分别命名为Adjustment_for_WIP、Desired_WIP、Desired_Production、Production_Adjustment_fr
5、om_Inventory、Desired_Inventory、Inventory_Coverage、Maximum_Shipment_Rate、Desired_Inventory_Coverage、Order_Fulfillment_Ratio、Desired_Shipment_Rate。6. 最后再从System Dynamics拖入一个Flow Aux Variable和一个Stock Variable。分别命名为Change_in_Exp_Orders和Expected_Order_Rate。在Expected_Order_Rate的Initial value中填写Customer_Or
6、der_Rate。以上的各种变量之间的关系和位置图如图3:图 37. 点击General,从中拖入一个Table Function,命名为Table_for_Order_Fulfillment,其具体参数如图4所示:图 48. 定义变量的值。以上拖入的变量的值如表1所示:表 1Production_Start_RateSwitch_for_Labor_in_Production * Labor * Workweek * Productivity + ( 1 - Switch_for_Labor_in_Production ) * Desired_Production_Start_RatePro
7、duction_Ratedelay3( Production_Start_Rate, Manufacturing_Cycle_Time )Shipment_RateDesired_Shipment_Rate * Order_Fulfillment_RatioDesired_Production_Start_RateDesired_Production + Adjustment_for_WIPAdjustment_for_WIP( Desired_WIP - Work_in_Process_Inventory ) / WIP_Adjustment_TimeDesired_WIPManufactu
8、ring_Cycle_Time * Desired_ProductionDesired_Productionmax( 0, Expected_Order_Rate + Production_Adjustment_from_Inventory )Production_Adjustment_from_Inventory( Desired_Inventory - Inventory ) / Inventory_Adjustment_TimeDesired_InventoryDesired_Inventory_Coverage * Expected_Order_RateInventory_Covera
9、geInventory / Shipment_RateMaximum_Shipment_RateInventory / Minimum_Order_Processing_TimeDesired_Inventory_CoverageMinimum_Order_Processing_Time + Safety_Stock_CoverageOrder_Fulfillment_RatioTable_for_Order_Fulfillment( Maximum_Shipment_Rate / Desired_Shipment_Rate )Desired_Shipment_RateCustomer_Ord
10、er_RateChange_in_Exp_Orders( Customer_Order_Rate - Expected_Order_Rate ) / Time_to_Average_Order_Rate第三步:创建劳动力逻辑模型1. 同第二步的第一小步方法一样,右键单击模型创建一个名字为Labor的Active Object Class。2. 同库存的原理一样,首先从System Dynamics里面拖入两个Stock Variable,分别命名为Vacancies和Labor,初始值为Desired_Vacancies和Desired_Labor。3. 再拖入六个Flow Aux Varia
11、ble分别命名为Vacancy_Cancellation_Rate、Vacancy_Creation_Rate、Vacancy_Closure_Rate和Hiring_Rate、Quit_Rate、Layoff_Rate,双击Vacancy_Creation_Rate连接到Vacancies,双击Vacancies连接到Vacancy_Closure_Rate和Vacancy_Cancellation_Rate,双击Hiring_Rate连接到Labor,双击Labor,连接到Quit_Rate和Layoff_Rate。4. 拖入两个Flow Aux Variable,分别命名为LaborEx
12、port和Desired_Production_Start_Rate,右键单击,各自选择Create Shadow,其中Desired_Production_Start_Rate再勾中External。5. 拖入9个Flow Aux Variable,分别命名为Vacancy_Cancellation_Time、Vacancy_Adjustment_Time、Average_Time_to_Fill_Vacancies、Average_Layoff_Time、Average_Duration_of_Employment、Labor_Adjustment_Time、Willingness_to_
13、Lay_Off、Productivity和Standard_Workweek,并勾中Constant。6. 最后再拖入12个Flow Aux Variable,分别命名为Desired_Vacancy_Cancellation_Rate、Desired_Vacancy_Creation_Rate、Maximum_Vacancy_Cancellation_Rate、Adjustment_for_Vacancies、Desired_Vacancies、Expected_Time_to_Fill_Vacancies、Desired_Hiring_Rate、Maximum_Layoff_Rate、Ad
14、justment_for_Labor、Expected_Productivity、Desired_Labor和Desired_Lay_Off_Rate。各个变量的布局如图5:图 57. 以上变量的值图表2所示:表 2Vacancy_Cancellation_Ratemin( Desired_Vacancy_Cancellation_Rate, Maximum_Vacancy_Cancellation_Rate )Vacancy_Creation_Ratemax( 0, Desired_Vacancy_Creation_Rate )Vacancy_Closure_RateHiring_RateH
15、iring_RateVacancies / Average_Time_to_Fill_VacanciesQuit_RateLabor / Average_Duration_of_EmploymentLayoff_Ratemin( Desired_Lay_Off_Rate, Maximum_Layoff_Rate )LaborExportLaborVacancy_Cancellation_Time2Vacancy_Adjustment_Time4Average_Time_to_Fill_Vacancies8Average_Layoff_Time8Average_Duration_of_Emplo
16、yment100Labor_Adjustment_Time13Willingness_to_Lay_Off0Productivity0.25Standard_Workweek40Desired_Vacancy_Cancellation_Ratemax( 0, -Desired_Vacancy_Creation_Rate )Desired_Vacancy_Creation_RateDesired_Hiring_Rate + Adjustment_for_VacanciesMaximum_Vacancy_Cancellation_RateVacancies / Vacancy_Cancellati
17、on_TimeAdjustment_for_Vacancies( Desired_Vacancies - Vacancies ) / Vacancy_Adjustment_TimeDesired_Vacanciesmax( 0, Expected_Time_to_Fill_Vacancies * Desired_Hiring_Rate )Expected_Time_to_Fill_VacanciesAverage_Time_to_Fill_VacanciesDesired_Hiring_RateExpected_Attrition_Rate + Adjustment_for_LaborMaxi
18、mum_Layoff_RateLabor / Average_Layoff_TimeAdjustment_for_Labor( Desired_Labor - Labor ) / Labor_Adjustment_TimeExpected_ProductivityProductivityDesired_LaborDesired_Production_Start_Rate / ( Standard_Workweek * Expected_Productivity )Desired_Lay_Off_RateWillingness_to_Lay_Off * max( 0, -Desired_Hiri
19、ng_Rate )第四步:创建界面1. 分别在Inventory和Labor里面创建如下的图形(图6和图7):图 6图 72. 将模型下面的Inventory和Labor拖入到Main的编辑区域,则在Main区域里面将出现图6和图7的图案。从General里面想Main中拖入一个Parameter,命名为OrderRate,Type选择double,再从System Dynamics里面拖入一个Flow Aux Variable,命名为OrderRateLink,值填写OrderRate,从General中拖入一个Event,命名为changeOderRate,具体参数如图8所示:图 8其中在
20、First occurrence time(absolute)中填入10+5*uniform_discr(0,4)。再从General里面拖入三个Connector,将OrderRateLink和inventory右侧连接起来,将inventory和labor对应的点连接起来,如图9:图 93. 从Controls里面拖入一个Radio Buttons,在Radio Buttons里面写入Sporadic和User controlled,再从其中拖入一个Slider,Orientation选择Vertical,勾中Link后,在其中填写OrderRate,Minimum value为0,Max
21、imum value为20000。4. 最后从Analysis里面拖入三个Time Plot,在第一个中点击Add date item,Title写Order Rate,value处写OrderRate,Interpolation处选择Step。再点击Add data item,Title写Shipment Rate,value处填写invenroty.Shipment_Rate,Interpolation处选择Linear。Time Window填写100,Vertical scale选择Fixed,From 0 to 20000,Display up to 250 latest sampl
22、es。同理,第二个也添加两个数据,第一个数据Title写Desired Labor,Value为labor.Desired_Labor,第二个数据Title为Labor,Value处写labor.Labor,Time Window为100,Vertical Scale选择Fixed,From-5000 to 5000。第三个也添加两个数据,第一个数据的Title为Desired Inventory,Value写inventory.Desired_Invenroty,Interpolation选择Linear,第二个数据的Title为Inventory,value处填写invenroty.Invenroty,Interpolation处填写Linear,Time Window为100,Vertical Scale选择Fixed,From 0 to 1000000。最后整个界面如图10:图 10 到目前为止关于Inventory workforce的模型就基本完成,运行过程中的截图如图11:
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