供应链习题课

1、1. Moon Micro is a small manufacturer of servers that currently builds all of its product in Santa Clara, California. As the market for servers has grown dramatically, the Santa Clara plant has reached capacity of 10,000 servers per year. Moon is considering two options to increase its capacity. The

2、 first option is to add 10,000 units of capacity to the Santa Clara plant at an annualized fixed cost of $10,000,000 plus $500 labor per server. The second option is to have Molectron, an independent assembler, manufacture servers for Moon at a cost of $2,000 for each server (excluding raw materials

3、 cost), raw materials cost $8,000 per server, and Moon sells each server for $15,000.Moon must make this decision for a two-year time horizon. During each year, demand for Moon servers has an 80 percent chance of increasing 50 percent from the year before and a 20 percent chance of remaining the sam

4、e as the year before. Molectron prices may change as well. They are fixed for the first year but have a 50 percent chance of increasing 20 percent in the second year and a 50 percent chance of remaining where they are.Using a decision tree to determine whether Moon should add capacity to its Santa C

5、lara plant or if it should outsource to Molectron. What are some other factors that would affect this decision that we have not discussed.Assume that a discount factor is 10 percent.注意：Moon已有设备产能为10,000,对两种方案都是一样提供该产能，所以比较增量需求 禾I润即可。Option ABase year 0Year 1Year 2Probability64%16%16%Year 2Revenue=(2

6、0,000-10,000)*15,000*0.64+(15,000-10,000)*150,000*(0.16+0.16)+(10,000-10,000)*15,000*0.04Variable cost = (20,000-10,000)*500*0.64 +(15,000-10,000)*500*(0.16+0.16) +(10,000-10,000)*500*0.04Fixed cos2=10,000,000Total cos2= Variable cost+ Total costProfit2= Revenues- Total costYear 1Revenue =(15,000-10

7、,000)*15,000*0.8+(10,000-10,000)*150,000*0.2Variable cost=(15,000-10,000)*500*0.8+(10,000-10,000)*500*0.2Fixed cost=10,000,000Total cost= Variable cost+ Total costProfit1 = Revenue- Total costBase Year 0Profit0=0NPVa = profit 0 profit 11 -kprofit12(1 k)Option B丫 :ar 240% Dam a ndM ole ctro n cost/se

8、rver22.500$ 2.000Probability32% 一DemandDennsindl 1 D1,00040% DBrnandl15jDOO y- Molactrcin cast/ssrveir22.5QD$ 2,40032%110% DsmandMolectron cost/seiwr110% DemandMolectrcin cost/serverMolectron cost/serverDemand15.000S 2.00015.ODD$ 2.4DQ15.000$ 2 .ODD15J00D$ 2.40010.000$ 2,000WJOOO$ 2.40口8%B%8%8%2%Yea

9、r 2Revenue=(22,500-10,000)*15,000*(0.32+0.32)+(15,000-10,000)*15,000*(0.08+0.08+0.08+0.08) +(10,000-10,000)*15,000*(0.02+0.02)Cost2 =(22,500-10,000)*(2000+8000) *0.32+(22,500-10,000)*( 2400+8000) *0.32 +(15,000-10,000)*(2000+8000)*(0.08+0.08)+(15,000-10,000)* (2400+8000)*(0.08+0.08) +(10,000-10,000)

10、*(2000+8000)*0.02 +(10,000-10,000)* (2400+8000)*0.02Profit2 = Revenue- Total Cost同理可得Year 1 ,Year 0利润，代入下式： ,11NPVB = profit 0 profit 1 profit 2 1k(1 k)2比较NPVa, NPVb大者为最优方案！2. Weekly sales of Hot Pizza are as follows:WeekDemand ($)WeekDemand ($)WeekDemand($)110859691122116611910102311879611924124810

11、21291Estimate demand for the next four weeks using a four-week moving average and simple exponential smoothing with o=0.1. Evaluate the MAD, MAPE, MSE, bias, and TS in each case. Which of the two methods do you prefer? Why?Refer to excel!3. Harley Davidson has its assembly plant in Milwaukee and its

12、 motorcycle assembly plant in Pennsylvania. Engines are transported between the two plants using trucks, with each trip costing $1000. The motorcycle plant assembles and sells 300 motorcycles each day. Each engine costs $500, and Harley incurs a holding cost of 20 percent per year. How many engines

13、should Harley load onto each truck? What is the cycle inventory of engines at Harley?Solution:2DSThe economic order quantity is given by . In this problem:D = 109,500 (i.e., 300 units/day multiplied by 365 days/year)S = $1000/orderH = hC =0.2*500 = $100/unit/yearQ* = 2DS =1480hCSo, theEOQ value is 1

14、480 unitsD _ Q，TC S 一hC DC =$147,986 Q 2So the total yearly cost is $147,986.The cycle inventory value is EOQ/2 = 1480/2 =7404. Prefab, a furniture manufacturer, uses 20,000 square feet of plywood per month. Their trucking company charges Prefab $400 per shipment, independent of the quantity purchas

15、ed. The manufacturer offers an all unit quantity discount with a price of $1 per square foot for orders under 20,000 square feet, $0.98 per square foot for orders between 20,000 square feet and 40,000 square feet, and $0.96 per square foot for orders larger than 40,000 square feet. Prefab incurs a h

16、olding cost of 20 percent per year. What is the optimal lot size for Prefab? What is the annual cost of such a policy? What is the cycle inventory of plywood at Prefab? How does it compare with the cycle inventory if the manufacturer does not offer a quantity discount but sells all plywood at $0.96

17、per square foot?Solution(1) For, price = $1.00 per unitQi= EOQ =2 20000 12 4000.2 1=30,984Since Qi> 19,999We select Qi= 20,000 (break point) and evaluate the corresponding total cost, which includes purchase cost + holding cost + order costTotal Cost尸 DC。Q1 hC0 S 2Qi2000020000 12= 20000 12 0.98 0

18、.2 0.98 400 = $ 241,960220000(2) For, price = $0.98 per unitQ2= eoq =2 20000 12 400312980.2 0.98Q2 =31298 20000,40000)Total Cost2 = DC1 Q2hC1 S 2Q2= 20000 12 0.983129820000 120.2 0.98 400 = $241,334231298(3) For, price = $0.96 per unit0.2 0.96Q3= EOQ =2 20000 12 400 =31623Q3 =31623 ：: 40000We select

19、 Q3= 40,000 (break point) and evaluate the corresponding total cost, which includes purchase cost + holding cost + order costTotal Cost3 = DC 2 Q3 hC2 2 S 2Q3= 20000 12 0.96316230.2 0.96 20000 12 400 =$236,640231623Total Cost3 <Total Cost 2 <Total Cost 1So, the optimal value of Q* = 40000 and

20、the total cost is $236,640The cycle inventory is Q*/2 = 40000/2 = 20000 (b) If the manufacturer did not offer a quantity discount but sold all plywood at $0.96 per square foot then Q = 31,623 and the total cost is $ 233,4365. Weekly demand for Motorola cell phones at a Best Buy store is normally dis

21、tributed, with a mean of 300 and a standard deviation of 200. Motorola takes two weeks to supply a Best Buy order. Best Buy is targeting a CSL of 95% and monitors its inventory continuously. How much safety inventory of cell phones should Best Buy carry? What should its ROP be.SolutionDl = LD = 2*30

22、0 = 600二 L = L O d = 200,2 = 283ss = Fs1 (CSL)二l = Fs1 (0.95)283 = 465(where, Fs1 (0.95) = NORMSINV (0.95)=1.6431)ROP = DL + ss = 600 + 465 = 10656. Assume that the Best Buy store in Exercise 1. The store manager has decided to review inventory every three weeks. Assuming a periodic review replenish

23、ment policy, evaluate the safety inventory that the store should carry to provide a CSL 95%. Evaluate the OUL for such a policy.SolutionDl = (T+L) D = (2+3)*300 = 1500oL = vfTLct D = 2002+3 = 447ss = Fs-1(CSL) ；=l = Fs-1(0.95) 447 = 736 (where,FS-1(0.95) = NORMSINV (0.95) =1.6431)OUL = D(T+L) + ss = 1500 + 736 = 2236Supply chain, cycle inventory, safety inventory, replenishment policy, continuous review, periodic review, produc