供应链设计与管理：概念、战略与案例研究课后答案-英文.pdf

【实例简介】
供应链设计与管理：概念、战略与案例研究++课后答案-英文
strategies in order to achieve this goal. Some of them focus on customer satisfaction and quick delivery, while others may be more concerned about minimizing inventory holding costs d. In general, different parts of the supply chain have objectives that are not aligned with edo ner 1. Purchasing: Stable order quantities, fiexible delivery lead times and little variation In mIX 2. Manufacturing: Long production runs, high quality, high productivity and low pro- duction costs 3. Warehousing Low inventory, reduced transportation costs and quick replenishment capability 4. Customers: Short order lead times, a large variety of products and low prices ypically. the automobile dealer would like to offer a variety of car colors and config urations to accommodate different, customer preferences, and meanwhile have a short delivery lead time from the manufacturer. However, in order to maximize the length of production runs, and utilize resources more efficiently, the manufacturer would like to aggregate orders fron dillerent dealers and offer less variety in car conligurations. This is a clear example of conflicting marketing and manufacturing goals a. The supply chain for a consumer mortgage offered by a bank may involve various com ponents 1. Marketing companies that handle solicitation to potential customers 2. Credit reporting agencies that evaluate potential customers 3. The bank that extends the mortgage loans 4. Mortgage brokers through which the loans are distributed b. The marketing companies strive to increase the response rate from homebuyers in order to maximize their returns. Banks aim at a customer portfolio with a relatively low risk hcalthy How of payments and low avcragc loan maturity datc. The brokers would like to maximize their sales commissions c. Similar to product supply chains, the objective of a service supply chain is to provide what is needed(in this case a particular type of service, rather than a physical product) at the right location, at the right time, and in a form that conforms to customer require ments while minimizing systemwide costs. However, there are a number of differences between the two types of supply chains. For instance 1. In a product supply chain, there is both a How of information and physical products In a service supply chain, it is primarily information 2. Contrary to a service supply chain, transportation and inventory are major cost components in a product supply chain 3. Services typically cannot be held in inventory, so matching capacity with demand is frequently more important in a service supply chain 4. In a service supply chain, the(explicit) cost of information is higher than in a product supply chain. Note that in the mortgage example above, the bank has to compensate the credit reporting agency for each credit report it obtains Many supply chains evolve over time. For example, consider a memory chip supply chain Production strategies may change during different stages of the product life cycle. W a new memory chip is introduced, price is high, yield is low, and production capacity is tight, and the availability of the product is important. Consequently, production is usually donc at plants closc to markets, and the management focuscs on incrcasing yicld reducing the number of production disruptions, and fully utilizing capacity. When the product matures, however, its price drops and demand is stabilized for a period of time so minimizing production cost moves to center stage. To reduce costs, production may be outsourced to overseas foundries, where labor and materials are much cheaper a vertically integrated company aims at tighter interaction among various business com ponents, and frequently manages them centrally. Such a structure helps to achieve sys- temwidc goals more casily by removing conflicts among different parts of the supply chain through central decision making. In a horizontally integrated company, there is frequently no benefit in coordinating the supply chains of each business within the company. Indeed if every business specializes in its core function, and operates optimally, an overall global optimum may be approached Effective supply chain management is also important for vertically integrated companies In such an organizational structure, various business functions are handled by different departments of the company that usually have different internal objectives, and these objectives are not necessarily aligned with each other. This may be due to lack of com munication among departments or the incentives provided by the upper management. For instance, if the sales department is evaluated based on revenue only, and the manufacturing department is evaluated based on cost only, the company's profit may not be maximized globally. Effective supply chain management is still necessary to achieve globally optimal operations The sources of uncertainty in this example include 1. Factors such as weather conditions, diseases, natural disasters cause uncertainty in availability of raw materials, i. e, peach crop 2. Uncertain lead times during transportation of crop from the field to the processing facility may affect the quality of peaches, e. g, they may get spoiled 4 3. Processing times in the plant, as well as the subsequent warehousing and transportation times are subject to uncertainty 4. Demand is not known in advance A small number of centrally located warehouses allows a firm to take advantage of risk pooling in order to increase service levels and decrease inventory levels and costs. However bound transportation cost is typically higher, and delivery lead times are longer. On the other hand by building a larger number of warehouses closer to the end customers. a firm can decrease outbound transportation costs and delivery lead times. However, this type of system will have increased total inventory levels and costs, decreased economies of scale, increases warehousing expenses, and potentially increased inbound transportation expenses The choice of the particular transport a t ion service depends largely on the types and sizes f products the company wants to transport, the inventory and delivery strategies and the need for Flexibility 1. A truckload carrier is bettor if delivering bulky items or small items in largc and stablc quantities from warehouses to demand points(stores). A good example is the delivery of groceries from warehouses to supermarkets. Note that in this case we would like the demand to be in increments of full truck loads 2. A package delivery firm is more appropriate if relatively small items are delivered from the manufacturer/warehouse directly to the customers. Additionally, a package carrier company offers more flexibility by different modes of transportation depending on the needs of the individual customers 1. High inventory levels i. Advantages: High fill rate(service level)and quick order fulfillment ii. Disadvantages: Iligh opportunity cost of capital tied in inventory, danger of price declines over time and obsolescence, need for more warehouse space 2. Low inventory levels i. Advantages: Low inventory holding and warehousing costs li. Disadvantages: Higher risk of shortages and lower service levels 5 Meditech experiences poor service levels for new products, and inventory levels higher than necessary for all products There are many causes for these problems 1. Demand is not studied in detail 2. Information systems that record and monitor demand and inventory are poorly designed 3. Forecasting errors are not tracked 4. There is a tendency to shift the blame to the customers, e. g, panic ordering 5. There are built-in delays and monthly buckets in the planning system 6. The planning system amplifies small variations in demand 7. Poor cOInmunication with custoners; Meditech doesn,t typically see enld-custoiner de mand The customer service manager is directly exposed to the complaints from the customers Hence, he is in a good position to gauge the scope of the problems. Other managers do not face the customers, and they do not necessarily focus on their satisfaction 1. Recognize that demand is predictable, and establish better forecasting systems and accountability for forecasts 2. Institute better planning systems to eliminate planning delays; reduce the size of system time buckets 3. Alternatively, put assembly within the pull system and eliminate bulk inventory com- pletely 4. Devclop and implement better information systcms 5. Improve colmnullicaLions with customers 6 The factors that affect the performance of the logistics network are not change over time. These factors include demand, product design, various costs in the logistics network, regulations, contracts, etc. The effects of these dynamics need to be evaluated periodically in order to determine whether the existing configuration is still satisfactory given the new operating environment For instance, service level requirements may change due to increased competition which typically means that the lead time to fulfill customer orders needs to be shortened. this may require the firm to redesign its logistic network and build new warehouses that are closer to the end customers The design of the logistics network is a strategic decision that has long lasting effects and impacts all functions within the company. For the success of such a project, many levels of the organization must be involved 1. Upper Management: The new design must be aligned with the vision and strategic goals of the company. Additionally, such a project may be costly, so management buy-in is essential to ensure that sufficient resources are devoted to the project 2. Sales and Marketing: Demand forecasts and anticipated changes in product design and offerings affect the network and need the involvement of sales and marketing teams 3. Manufacturing and Operations: The logistics network design has obvious impact on day to-day operation of the firm. In order for the implementation to succeed, it is essential that the people involved with operating the system on a daily basis are involved in its design The decision that a warehouse will be built has been made up-front Therefore. we only need to focus on the of the warehouse and determine how much space should be allocated to each product in the warehouse. The main steps of the analysis are outline below 1. Data collection Location of retail stores warehouses (5 warehouses located in Atlanta, Boston, Chicago, Dallas and Los Angeles), manufacturing facilities(a single man ufacturing facility in San Jose), and suppliers i. Candidate locations for the warehouse iii. Informa tion a bout products, i. e, their sizes, shapes and volumes iv. Annual demand(past actuals and future estimates) and service level requirements of the retail stores v. Transportation rates by available modes vi. Transportation distances from candidate warehouse locations to retail stores vii. Handling, storage and fixed costs associated with warehousing. Fixed costs should be expressed as a function of warehouse capacity viii. Fixed ordering costs, order frequencies and sizes by product or product famil 2. Data aggregation. Demand needs to be aggregated based on distribution patterns and or product types. Replace aggregated demand data points by a single customer 3. Mathematical model building 4. Model validation based on existing network structure 5. Selection of a few low cost alternatives based on the mathematical model i. For the final decision, incorporate qualitative factors that were disregarded in the mathematical model, e. g, specific regulations, environmental factors, etc li. Optionally, build a detailed simulation model to evaluate these low cost candidate solutions 6. Decide where to locate the centralized warehouse With the centralized warehouse, service level will increase(less stock-outs)and inven. tory holding costs will decrease due to risk pooling. Also, fixed costs associated with ware housing will typically decrease, and inbound transportation costs from the manufacturing facility to the warehouse shiould be less than the suIn of the previous inbound transporta tion costs. However, we will incur increased outbound transportation costs from the central warehouse to the retailers. In summary, the essential design trade-off is between trans portation costs on one hand, and inventory holding costs and service level requirements on the othe a. In automobile manufacturing, cars are usually delivered over land, and demand is con centrated around major cities. Therefore, we would expect warehouses in this industry to be located near large cities with easy access to freeways and railroads. This would help to reduce the delivery lead time to dealerships in the cities b. In the pharmaceutical industry, overnight delivery is common. Therefore, proximity to a major airport is a factor that should be considered when choosing a warehouse location. Additionally, for raw material warehouses it is important that these are close to natural rcsources c. In the book industry, supplier warehouse locations would be affected by the availability of nearby natural rcsourccs d. In the aircraft manufacturing industry, sub-assemblies and parts are delivered by thou- sands of suppliers scattered all over the globe to the manufacturing facilities. Therefore for these supplier warehouses, by far the most significant consideration is the ability to ship parts easily and on-time, i.e., the proximity to railroads, freeways, harbors, etc In such a capital intensive industry, we would also expect that regulations such as tax breaks have an impact on potential warehouse locations e. With a large customer base shopping for books on-line, short delivery lead times are crucial. Therefore in book distribution, we would expect to find large centralized ware houses on reasonably priced land and where quick transportation modes are available f. Furniture manufacturing and distribution depends heavily on manual labor. Therefore warehouses in this industry should be located close to cities with sufficient labor supply. g. In PC manufacturing, outsourcing from all around the world is common where labor is cheaper and regulations favor the huge investments associated with high-tech manufac turing. These considerations should be factored in when choosing candidate warehouse locations In the pharmaceutical industry, we would expect more warehouses closer to the end cus tomers for short delivery lcad times. On the other hand, in the chcmical industry therc would be fewer centralized warehouses in order to consolidate orders and decrease outbound transportation costs If we expect that the truck would travel on its return route. then tl rate would be higher. Considering the exalmple in Section 2.2.2, the probability that the truck comes back empty from Illinois(industrial heartland )to Now York is lowcr than thc corrcsponding probability from new york to illinois which explains the asymmetric cost structure between these two citi 1. Handling Costs i. Labor cost of workers in material handling 9 ii.Costs of conveyors, fork lifts, automated guided vehicles(AGVs),etc, used to carry the goods in the warehouse. Note that these costs have two components: variable costs that are linearly proportional to the distances the goods are transported over and purchasing costs of cquipmcnt that are proportional to the daily output rcquircd from the material handling system, but in a non-linear way because equipment is purchased in discrete quantities 2. Fixed costs i. Purchasing or rental cost of land ii. Cost of maintaining and operating the warehouse building which ncludes annua depreciation and utility costs ii. Cost of racks that depend on the capacity of the warehouse iv. The cost of insurance for the facility 3. Storage costs i. Opportunity cost of capital tied up in inventory ii. Cost of price declines while inventory is sitting in the warehouse. Note that this includes the risk of obsolete inventory that needs to be salvaged An exact optimization technique is guaranteed to provide an optimal solution(if one exists even if it lakes a long time. On the other hand. a heuristic algorithim is a method that will find good solutions to the problcm in a rcasonablc amount of timc where the terms good"and"reasonable depend on the heuristic and the particular problem instance. ( See Bramel and Simchi-Levi(1997). ) The choice between an exact optimization technique and a heuristic algorithm for a given problem frequently depends on the trade-off between solution quality and solution time. Note that even if a heuristic algorith(by chance finds the optimal solution to a problem, it cannot confirm the optimality of the solution On the other hand, for many problems there are no known optimal algorithms, so heuristics must be used Simulation is a popular performance evaluation and modeling tool for complex stochastic systems that cannot be evaluated analytically. A simulation model can closely reflect a real system and mimic its behavior, but it has some drawbacks: simulation is a tool, i. e, it, cannot provide optimal va lues for system inputs. It generates, for a set of inputs, sample outputs from the system that are used to compute statistical estimates of the performance measures. Also, accurate simulation models of large systems require extensive development effort, and typically take a long time to run. Thus, we advocate a two-phase approach to solve difficult logistics problems 1. Use a mathematical optimization model to generate a number of good candidate solutions, taking into account the most important cost components 【实例截图】
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