Supply Chain Management New Perspectives Part 12 doc

Reverse Supply Chain Management - Modeling Through System Dynamics 427 Selected Variables 2,000 1,500 1,000 500 0 0 50 100 150 200 250 300 350 400 450 500 Time (Week) unit/Week D : Current PR : Current RPR : Current Fig. 6. Demand, production and reprocessing Selected Variables 200 unit/(Week*Week) 1,000 unit/Week 100 unit/(Week*Week) 500 unit/Week 0 unit/(Week*Week) 0 unit/Week 0 75 150 225 300 375 450 Time (Week) CCIR : Current unit/(Week*Week) CCRR : Current unit/(Week*Week) COR : Current unit/Week Fig. 7. Collection capacity The collection capacity (Fig. 7) and the reprocessing capacity (Fig. 8) increase or decrease according to the growth or reduction decisions they receive. Supply Chain Management - New Perspectives 428 Selected Variables 400 unit/(Week*Week) 2,000 unit/Week 200 unit/(Week*Week) 1,000 unit/Week 0 unit/(Week*Week) 0 unit/Week 0 75 150 225 300 375 450 Time (Week) RCIR : Current unit/(Week*Week) RCRR : Current unit/(Week*Week) RPC : Current unit/Week Fig. 8. Reprocessing capacity For the residence time (Fig. 9), a random sample of values has been estimated according to a normal probability distribution with a minimum of 10 weeks, a maximum of 30 weeks, and an average of 20 weeks with a standard deviation of 2 weeks. RT 40 32.5 25 17.5 10 0 50 100 150 200 250 300 350 400 450 500 Time (Week) Week RT : Current Fig. 9. Residence time Reverse Supply Chain Management - Modeling Through System Dynamics 429 The volume of collected products usually exceeds the number of reusable products until the end of the life of the product, when it increases (Fig. 10). Selected Variables 2,000 1,500 1,000 500 0 0 50 100 150 200 250 300 350 400 450 500 Time (Week) unit CP : Current REP : Current Fig. 10. Collected products and reusable products The system also tends to ensure that the number of products disposed in an uncontrolled manner stabilizes at values lower than those of the controlled disposal (Fig.11) Selected Variables 80,000 60,000 40,000 20,000 0 0 50 100 150 200 250 300 350 400 450 500 Time (Week) unit DP : Current UDP : Current Fig. 11. Controlled and uncontrolled disposed products Supply Chain Management - New Perspectives 430 Selected Variables 6 M 4.5 M 3 M 1.5 M -4 0 50 100 150 200 250 300 350 400 450 500 Time (Week) €/Week ILI : Current SI : Current Fig. 12. Revenue The revenue of the chain (Fig. 12) comes from sales and the final liquidation of the inventories. Selected Variables 20 M 15 M 10 M 5 M 0 0 50 100 150 200 250 300 350 400 450 500 Time (Week) €/Week ICOST : Current OCOST : Current Fig. 13. Costs Reverse Supply Chain Management - Modeling Through System Dynamics 431 The costs of the chain (Fig. 13) can either be operating costs or investment costs. The operating costs essentially correspond to storage, transport and production and reprocessing. The NCV of the whole chain has been estimated (Fig.14), showing that with the parameters set for this model, the investment is recovered after week 165. It can also be noted that there is a recovery of value as a result of the liquidation of inventories. NPVWN 60 M 30 M 0 -30 M -60 M 0 50 100 150 200 250 300 350 400 450 500 Time (Week) € NPVWN : Current Fig. 14. Cumulative NCV of model As anticipated at the beginning of this part of the section, the model is highly generic and the answers obtained can vary greatly as a function of the input parameters which are set according to the type of product and its life cycles. However, the parameters of expansion and contraction of the collection and reprocessing capacities (Kc1. KC2, KR1 and KR2) have a great impact on the results and this phenomenon should be analyzed in some future work. 6. Conclusion The model developed represents quite accurately the behavior of a reverse supply chain for a single product with reprocessing, so that the main proposal of this part of the work is considered to be achieved. Phenomena such as the Bullwhip effect are represented in the model as well as phenomena such as saturation on reaching the peak of the productive capacity, and delays in the system responses resulting from the inertias acquired in the operations. The assessment of costs and revenues represents the phenomena of investment and disinvestment in a logical way and the cumulative net present value shows that in the case simulated, gains are made and it is therefore viable. It should not be forgotten that this is a Supply Chain Management - New Perspectives 432 test case, a dummy, so that depending on the type of product that the model is applied to, the economic results can vary significantly. In short, we consider that modeling with system dynamics is an effective tool for describing reverse logistics systems due to the existence of delays and feedback loops. Moreover, system dynamics is a highly valuable and affordable method for performing simulations since all the variables and parameters are known; it is thus distinct form other simulation techniques that have more of a "black box" nature. Therefore we can conclude that it is a highly useful tool for decision-making. 7. Annex 1. Model variables VARIABLE OR PARAMETE R SIGNIFICANCE OF VARIABLE OR PARAMETER a-CC Parameter of delay in collection capacity a-D Parameter delay in demand a-DI Parameter of delay in distributors’ inventory a-MI Parameter of delay in wholesalers’ inventory a-RI Parameter of delay in retailers’ inventory a-RPC Parameter of delay in reprocessing a-RR Parameter of delay in reprocessing ratio CCCCOST Costs of constructions for collection capacity CCCR Ratio of contraction of collection capacity CCDE Desired collection capacity CCDI Discrepancy in collection capacity CCER Ratio of expansion of collection capacity CCIR Ratio of increase in collection capacity CCOST Collection costs CCRCOST Costs of reduction in collection capacity CCRR Ratio of reduction in collection capacity CCWCOST Weekly costs of collection capacity CD Controlled disposal CIC Coefficient of investment in collection COR Collection capacity CP Collected products CR Collection ratio CTCOST Costs of transport to clients CWCOST Weekly costs of collection Reverse Supply Chain Management - Modeling Through System Dynamics 433 VARIABLE OR PARAMETE R SIGNIFICANCE OF VARIABLE OR PARAMETER D Orders DB Backorders DCT Time of delivery to clients DI Distributors’ inventory DIAT Time of adjustment of distributors’ inventory DICT Time of coverage of distributors’ inventory DID Discrepancy with distributors’ inventory DIDE Inventory of desired distributors DIL Liquidation of distributors’ inventory DILI Revenue from liquidation of distributors’ inventory DILT Time of liquidation of distributors’ inventory DISCOST Cost of storage of distributors’ inventory DISWCOST Weekly cost of storage of distributors DLP Distributors’ liquidation price DO Distributors’ orders DORR Ratio of reduction of backorders DP Waste products DST Time of delivery to distributors DTCOST Cost of transport to distributors DTWCOST Weekly cost of transport to distributors ED Expected demand EDO Orders expected from distributors EMO Orders expected from wholesalers ERO Orders expected from retailers FP Percentage of error ICOST Investment costs ILI Revenue from liquidation of inventories ILPI Revenue from liquidation of inventories of the plant IT Inspection time Kc1 Parameter of increase in collection capacity Kc2 Parameter of reduction in collection capacity Kr1 Parameter of increase in reprocessing capacity Supply Chain Management - New Perspectives 434 VARIABLE OR PARAMETE R SIGNIFICANCE OF VARIABLE OR PARAMETER Kr2 Parameter of reduction in reprocessing capacity LPP Liquidation price in plant MBO Wholesalers’ Backorders MFL Minimum for liquidation MI Wholesalers’ inventory MIAT Time of adjustment of wholesalers’ inventory MICT Time of coverage of wholesalers’ inventory MIDE Inventory of desired wholesalers MIDI Discrepancy with wholesalers’ inventory MIL Liquidation of wholesalers’ inventory MILI Revenue from liquidation of wholesalers’ inventory MILT Time of liquidation of wholesalers’ inventory MISCOST Storage costs of wholesalers’ inventory MISWCOST Weekly storage cost of wholesalers’ inventory MLP Price of liquidation of retailers MLPR Price of liquidation of wholesalers MO Wholesalers’ orders MOBRR Ratio of reduction in wholesalers’ backorders MP Materials for processing MS Deliveries to wholesalers MSICOST Storage costs of retailers’ inventory MSIWCOST Weekly storage costs of retailers’ inventory MST Time of delivery to wholesalers MTCOST Cost of transport to wholesalers MTWCOST Weekly cost of transport to wholesalers NCF Net cash flow NPVP Current value of the period NPVWN Current net value of the whole network OB Backorders OBRR Ratio of reduction of backorders OCOST Operating costs PARU Products accepted for reuse Reverse Supply Chain Management - Modeling Through System Dynamics 435 VARIABLE OR PARAMETE R SIGNIFICANCE OF VARIABLE OR PARAMETER PC Production capacity PCOST Production costs PD Peak demand PLIR Revenue from liquidation of retailers’ inventories PR Production ratio PRR Products rejected for reuse PT Production Time PTCOST Total costs per period RCC Coefficient of reduction in collection RCCCOST Costs of constructions for reprocessing capacity RCCR Ratio of contraction in reprocessing capacity RCDE Desired reprocessing capacity RCER Ratio of expansion of reprocessing capacity RCIR Ratio of increase in reprocessing capacity RCRCOST Costs of reduction in reprocessing capacity RCRR Ratio of reduction in reprocessing capacity RCWCOST Weekly cost of reprocessing capacity REP Reusable products RER Expected reprocessing ratio RI Retailers’ inventory RIAT Time of adjustment to retailers’ inventory RICOST Coefficient of investment in reprocessing RICT Time of coverage of retailers’ inventory RIDE Inventory of desired retailers’ inventory RIDI Discrepancy with retailers’ inventory RIL Liquidation of retailers’ inventory RILT Time of liquidation of retailers’ inventory RO Retailers’ orders ROB Retailers’ backorders ROBRR Ratio of reduction of retailers’ backorders RPC Reprocessing capacity RPCD Discrepancy with reprocessing capacity Supply Chain Management - New Perspectives 436 VARIABLE OR PARAMETE R SIGNIFICANCE OF VARIABLE OR PARAMETER RPCOST Reprocessing costs RPR Reprocessing ratio RPSCOST Cost of storage of reusable products RPT Reprocessing time RRC Coefficient of reduction in reprocessing RS Deliveries to retailers RSKT Waiting time for reusable stock RSPWCOST Weekly cost of storage of reusable products RST Time of delivery to retailers RT Time of residence RTCOST Cost of transport to retailers RTWCOST Weekly cost of transport to retailers RWCOST Weekly cost of reprocessing S Sales SD Deliveries to distributors SI Revenue from sales SMPO Products sent to secondary markets SP Sales price STWCOST Weekly cost of sales transport TIP Total revenue per period Tc1 Time of increase in collection capacity Tc2 Time of reduction in collection capacity TPD Total demand pattern Tr1 Time of increase in reprocessing capacity Tr2 Time of reduction in reprocessing capacity UD Uncontrolled disposal UDP Products disposed of uncontrollably UI Useful inventory UIAT Time of adjustment to useful inventory UICT Time of coverage of useful inventory UID Discrepancy with useful inventory UIDE Desired useful inventory [...]... organisation’s supply chain may pass through the supply chains of many suppliers or manufacturers on their way to the organisation and outputs from an organisation may pass through many distributors, retailers or customer’s supply chains before it reaches the final customer (Ward & Peppard, 2002) This can be referred to as a supply chain network (SCN) Supply chains and SCNs have become an integral part of... Kingdom Department for International Development www.etfrn.org/etfrn/workshop/ntfp/download.html (Accessed June 2010) Part 5 Competing Through Information and Technologies 22 Web Technologies and Supply Chains Alexis Barlow Glasgow Caledonian University Scotland 1 Introduction This chapter is concerned with examining the role of web technologies across the field of supply chains and supply chain management. .. which have transformed business 462 Supply Chain Management - New Perspectives strategies, business models, supply chains and business processes It is an exciting field that offers many new opportunities but poses many different challenges (Li, 2007) 2.1 Internet & world wide web The origins of the Internet can be traced back to a military project commissioned by the US Department of Defence in 1969 The... units 440 Supply Chain Management - New Perspectives ( 112) RER= SMOOTH(RPR, "a-RR") Units: units/week (113) RI= INTEG (RS-RIL-S,0) Units: units (114) RIAT= 1 Units: week (115) RICOST=RCER^0.6 Units: units/week (116) RICT= 2 Units: week (117) RIDE=ED*RICT Units: units (118) RIDI= MAX(RIDE-RI, 0) Units: units (119) RIL=IF THEN ELSE(RIDElbr, RCDE-RPC, 0) Units: units/week (126 ) RPCOST=25 Units: €/units (127 ) RPR= MAX( MIN(REP/RPT, RPC), 0) Units: units/week (128 ) RPSCOST= 0.4 Units: €/(week*units) (129 ) RPT= 1 Units: week (130) RPWCOST=... processes, and in particular for collaboration, integrating business processes and developing visibility and information sharing across SCNs It will highlight a range of challenges related to the use of web technology for supply chains and supply chain management such as trust, security, social and cultural issues and depersonalisation and the chapter will close by discussing future trends in supply chains and... This chapter examined the various stages of NTFPs supply chain in Ghana, the actors involved in the chain and its key challenges The study revealed that the supply chain of NTFPs in Ghana faces a number of critical challenges from the production to the marketing stage The chapter identified number of strategies for improving the management of NTFPs supply chain in Ghana These include processing and marketing... announcements/bulletins, corporate documents, staff lists, phone directories, human resource issues, health and safety regulations, training materials etc Individual departments may have web sites linked to the intranet which can be used for identifying who’s who in the department, what’s new in the department, departmental products/services, projects the department are involved in and relevant documents and tools... the local, regional, national and international level Improving the supply chain of NTFPs has become very important in the efforts of most developing countries trying to enhance the economic empowerment of the rural poor This chapter seeks to examine the NTFPs supply chain activities, actors and the key challenges of supply chain management 1.1 Definition and classification of NTFPs NTFPs are “biological... technologies across the field of supply chains and supply chain management (SCM) Supply chains and SCM are growing concerns for organisations as customers become more demanding, cost reduction is becoming more and more important and supply chains are increasingly complex as globalisation and the use of global partners becomes greater Supply chains embrace all those processes involved in creating and delivering . Supply Chain Management - New Perspectives 430 Selected Variables 6 M 4.5 M 3 M 1.5 M -4 0 50 100 150 200 250 300 350 400 450 500 Time (Week) €/Week ILI : Current SI : Current Fig. 12. . RICOST*RCCCOST+RRC*RCRCOST Units: €/week (111) REP= INTEG (PARU-CD-RPR,0) Units: units Supply Chain Management - New Perspectives 440 ( 112) RER= SMOOTH(RPR, "a-RR") Units: units/week (113) RI= INTEG. & Logistics Management, vol. 25, no. 2, pp. 56. Martín Garcia, J. 2003, Teoría y Ejercicios prácticos de Dinámica de Sistemas, ed. el autor. Supply Chain Management - New Perspectives