Management Engineering - Logistics Management

Full exam

LOGISTICS MANAGEMENT A.Y. 2021 -22 -Prof. Marco Melacini 2nd call -February 11th 2022 EXERCISE 1 2 lOMoARcPSD|20562176 EXERCISE 1.1 Consider an AS/RS warehouse whose layout is shown in Figure 1, consisting of 4 storage aisles with double -deep storage racks. The I/O system is located at the first level. A conveyor connects storage area to 4 picking stations. The unit loads (ULs) handled by the AS/RS warehouse are palletized ULs. At the picking stations, the pickers pick cartons from the ULs. Assuming the following additional information: number of storage levels: 10; number of storage columns: 30; gross size of each storage location (= storage bay): 2,600 (depth) * 1,800 * 1,600 (height) mm; each storage location can hold 4 ULs; number of forks per each S/R machine: 1; item allocation to the storage locations: random; horizontal speed: 2.5 m/s; vertical speed: 1.1 m/s; fixed time for positioning: 4 s; fork cycle time: 5 s; acceleration + deceleration delay: 6 s; S/R machines availability: 100%; the required UL is never stored behind another UL (assumption only for Exercises 1.1 to 1.3); the expected cycle time can be estimated through FEM 9851 rule, Estimate the average single command cycle time. Enter your answer 3 EXERCISE 1.2 Considering the same setting described in Exercise 1.1, estimate the average dual command cycle time. Enter your answer 4 EXERCISE 1.3 Considering the AS/RS warehouse described in Exercise 1.1 and the following assumptions: the warehouse works 3 shifts/day; the storage activity is performed every day during the third shift; carton picking is performed every day during the first and second shift; on average, the number of customers orders is 10 orders/hour; on average, each order consists of 10 order lines, with 3 cartons per order line; in 90% of the cases, the UL is not empty after the picking activity and returns into the storage area, Estimate the target throughput capacity [UL/hour] of the automated warehouse during the picking activity. Enter your answer 5 EXERCISE 1.4 Considering the AS/RS warehouse described in Exercise 1.1 and the following assumptions: percentage of single -command cycles: 100%; in 50% of the cycles, the required UL is stored behind another UL (i.e. in the second line of the double -deep rack). Whenever this happens, the average time required for the additional activities of the S/R machine (moving the UL to an empty location and going back) is 1 minute, Estimate the throughput capacity of one S/R machine during the picking activity. Enter your answer LOGISTICS MANAGEMENT A.Y. 2021 -22 -Prof. Marco Melacini 2nd call -February 11th 2022 EXERCISE 2 6 EXERCISE 2.1 The company CAT&DOG is a manufacturer of fresh petfood that wants to start up a last -mile deliver y service in the city of Milano .The delivery, performed by means of vans, will start from awarehouse located 30 km far from the city . Considering the following assumptions : size of the delivery area: 250 km2; number of customers in the area: 90; the distribution of customers inside the area is random uniform; average van speed outside the city: 45 km/h; average truck speed inside the city: 20 km/h; every stop at the customer lasts 10 minutes ; each customer is visited three times a week ; average order weight :60 kg ; average order volume :0.04 m 3; the van has acapacity of 1.2 tons and 5 m 3; each van performs one tour per day ;the shift of a van lasts 8 hours ; 6 working days/week ; rectilinear paths inside the delivery area (coefficient = 1.15 ), Estimate the expected distance between two customers by applying the Daganzo model. Enter your answer 2/11/22, 10:30 AM LOGISTICS MANAGEMENT A.Y. 2021 -22 -Prof. Marco Melacini 2nd call -February 11th 2022 (Page 3of6) 7 EXERCISE 2.2 Considering the same setting described in Exercise 2.1, and neglecting the weight and volume constraints, estimate the required fleet size. Enter your answer 8 EXERCISE 2.3 Considering the same setting described in Exercise 2.1, estimate the required fleet size. Enter your answer lOMoARcPSD|20562176 LOGISTICS MANAGEMENT A.Y. 2021 -22 -Prof. Marco Melacini 2nd call -February 11th 2022 EXERCISE 3 The company ALFA isan Italian electronics retailer whose distribution network isshown in Figure 2. The company sells its products through both a traditional channel (100 stores) and an eCommerce channel. For the eCommerce channel, customer orders are fulfilled by 3 picking warehouses (PWs). In the current network configuration, each PW serves the customers located in a specific geographical area (Figure 2). As shown in Figure 2, both the stores and the PWs are replenished by a central warehouse (CW). Focusing on one of the products sold by the company, called MICROWAVE, the company wants to investigate the impact of safety stocks. 9 EXERCISE 3.1 Assuming the following information: the weekly demand of each store follows a normal distribution with mean value equal to 3 units and standard deviation equal to 1 unit; for the eCommerce channel, the weekly demand of each geographical area follows anormal distribution with mean value equal to 20 units and standard deviation equal to 3 units; allocation strategy of safety stock: coupled system; the CW is replenished from suppliers once every 2 weeks. The replenishment lead time follows a normal distribution with mean value equal to 5 days and standard deviation equal to 2 days; the stores and PWs are replenished from the CW once a week; the replenishment lead time between the CW and each store or PW is constant and equal to 2 days; there is a positive linear correlation between the demands seen by PW1 and PW2. The correlation coefficient is 0.2; the service level, measured as the Item Fill Rate, must be not lower than 90% in the PWs; the values for the unit normal loss integral are reported in Table 1; 5 working days/week; 48 weeks/year, Assess the amount of safety stock in the first picking warehouse (PW1). Enter your answer lOMoARcPSD|20562176 10 EXERCISE 3.2 Considering the same setting described above and the following additional information: storage cost in the PWs: 20 €/(unit*year); cost of capital: 5%/year; value of the product held at the PWs: 150 €/unit, Assess the yearly inventory carrying costs for safety stock held in PW1. Enter your answer 11 EXERCISE 3.3 Considering the same setting described above and focusing on the eCommerce channel, determine the standard deviation of the demand seen by the CW. Enter your answer 12 EXERCISE 3.4 Considering the same setting described above, the company is evaluating the introduction of a “virtual warehouse” strategy for the eCommerce channel, with a dynamic allocation of customers orders. This strategy would imply that customers orders could be fulfilled by any PW, regardless of the customer geographical area. What is the expected service level (in terms of Item Fill Rate) if this strategy is adopted? Enter your answer LOGISTICS MANAGEMENT A.Y. 2021 -22 -Prof. Marco Melacini 2nd call -February 11th 2022 QUESTIONS 13 QUESTION 1 Considering the design of the warehouse picking area in case of picker -to -parts system, you are required to explain how the replenishment frequency of the picking locations affects the warehousing costs. Enter your answer 14 QUESTION 2 Explain the importance of a Supply Chain perspective in road transportation management, also providing some examples. Enter your answer