Inventory-management-库存管理--外文翻译.doc

Floyd D. Hedrick, Library of Congress, Washington, D.C.
Editor: Jeannette Budding, Communications Manager
National Association of Purchasing Management

Inventory management

Abstract

Inventory management, or inventory control, is an attempt to balance inventory needs and requirements with the need to minimize costs resulting from obtaining and holding inventory. There are several schools of thought that view inventory and its function differently. These will be addressed later, but first we present a foundation to facilitate the reader's understanding of inventory and its function
Inventory management is inventory management in short .As an important inventory of liquid assets, its existence is bound to take up a lot of liquidity. In general, inventories of industrial enterprises accounted for about 30% of the total assets of commercial circulation enterprises is even higher, the management of utilization is directly related to the occupation of the level of corporate funds and asset efficiency. Therefore, a business to maintain high profitability, should be attached great importance to inventory management. Inventory management at different levels, the company's average occupancy level of funding is a big difference. Through the implementation of proper inventory management methods to reduce the level of the average amount of funds used to improve the inventory turnover rate and total assets, will ultimately improve the economic efficiency of enterprises
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Keyword： Inventory； Management

ChapterⅠ Inventory Definition
Inventory is a quantity or store of goods that is held for some purpose or use (the term may also be used as a verb, meaning to take inventory or to count all goods held in inventory). Inventory may be kept "inhouse," meaning on the premises or nearby for immediate use; or it may be held in a distant warehouse or distribution center for future use. With the exception of firms utilizing just-in-time methods, more often than not, the term "inventory" implies a stored quantity of goods that exceeds what is needed for the firm to function at the current time (e.g., within the next few hours).

Chapter II The meaning of Inventory Management

2.1 maintain the list
Why would a firm hold more inventory than is currently necessary to ensure the firm's operation? The following is a list of reasons for maintaining what would appear to be "excess" inventory.
Table 1

January
February
March
April
May
June
Demand
50
50
0
100
200
200
Produce
100
100
100
100
100
100
Month-end inventory
50
100
200
200
100
0

Table 1 1-6 month a business demand production, end balance situation

2.2 Meet demand
In order for a retailer to stay in business, it must have the products that the customer wants on hand when the customer wants them. If not, the retailer will have to back-order the product. If the customer can get the good from some other source, he or she may choose to do so rather than electing to allow the original retailer to meet demand later (through back-order). Hence, in many instances, if a good is not in inventory, a sale is lost forever.

2.3 Keep operations running
A manufacturer must have certain purchased items (raw materials, components, or subassemblies) in order to manufacture its product. Running out of only one item can prevent a manufacturer from completing the production of its finished goods.
Inventory between successive dependent operations also serves to decouple the dependency of the operations. A machine or workcenter is often dependent upon the previous operation to provide it with parts to work on. If work ceases at a workcenter, then all subsequent centers will shut down for lack of work. If a supply of work-in-process inventory is kept between each workcenter, then each machine can maintain its operations for a limited time, hopefully until operations resume the original center.

2.4 Lead time
Lead time is the time that elapses between the placing of an order (either a purchase order or a production order issued to the shop or the factory floor) and actually receiving the goods ordered. If a supplier (an external firm or an internal department or plant) cannot supply the required goods on demand, then the client firm must keep an inventory of the needed goods. The longer the lead time, the larger the quantity of goods the firm must carry in inventory.
A just-in-time (JIT) manufacturing firm, such as Nissan in Smyrna, Tennessee, can maintain extremely low levels of inventory. Nissan takes delivery on truck seats as many as 18 times per day. However, steel mills may have a lead time of up to three months. That means that a firm that uses steel produced at the mill must place orders at least three months in advance of their need. In order to keep their operations running in the meantime, an on-hand inventory of three months' steel requirements would be necessary.

2.5 Hedge
Inventory can also be used as a hedge against price increases and inflation. Salesmen routinely call purchasing agents shortly before a price increase goes into effect. This gives the buyer a chance to purchase material, in excess of current need, at a price that is lower than it would be if the buyer waited until after the price increase occurs.
2.6 Smoothing requirements
Sometimes inventory is used to smooth demand requirements in a market where demand is somewhat erratic. Consider the demand forecast and production schedule outlined in Table1
Notice how the use of inventory has allowed the firm to maintain a steady rate of output (thus avoiding the cost of hiring and training new personnel), while building up inventory in anticipation of an increase in demand. In fact, this is often called anticipation inventory. In essence, the use of inventory has allowed the firm to move demand requirements to earlier periods, thus smoothing the demand.

Chapter III Controlling Inventory

Often firms are given a price discount when purchasing large quantities of a good. This also frequently results in inventory in excess of what is currently needed to meet demand. However, if the discount is sufficient to offset the extra holding cost incurred as a result of the excess inventory, the decision to buy the large quantity is justified.
Firms that carry hundreds or even thousands of different part numbers can be faced with the impossible task of monitoring the inventory levels of each part number. In order to facilitate this, many firm's use an ABC approach. ABC analysis is based on Pareto Analysis, also known as the "80/20" rule. The 80/20 comes from Pareto's finding that 20 percent of the populace possessed 80 percent of the wealth. From an inventory perspective it can restated thusly: approximately 20 percent of all inventory items represent 80 percent of inventory costs. Therefore, a firm can control 80 percent of its inventory costs by monitoring and controlling 20 percent of its inventory. But, it has to be the correct 20 percent.
The top 20 percent of the firm's most costly items are termed "A" items (this should approximately represent 80 percent of total inventory costs). Items that are extremely inexpensive or have low demand are termed "C" items, with "B" items falling in between A and C items. The percentages may vary with each firm, but B items usually represent about 30 percent of the total inventory items and 15 percent of the costs. C items generally constitute 50 percent of all inventory items but only around 5 percent of the costs.
By classifying each inventory item as an A, B or C the firm can determine the resources (time, effort and money) to dedicate to each item. Usually this means that the firm monitors A items very closely but can check on B and C items on a periodic basis (for example, monthly for B items and quarterly for C items).
Another control method related to the ABC concept is cycle counting. Cycle counting is used instead of the traditional "once-a-year" inventory count where firms shut down for a short period of time and physically count all inventory assets in an attempt to reconcile any possible discrepancies in their inventory records. When cycle counting is used the firm is continually taking a physical count but not of total inventory.
A firm may physically count a certain section of the plant or warehouse, moving on to other sections upon completion, until the entire facility is counted. Then the process starts all over again.
The firm may also choose to count all the A items, then the B items, and finally the C items. Certainly, the counting frequency will vary with the classification of each item. In other words, A item may be counted monthly, B items quarterly, and C items yearly. In addition the required accuracy of inventory records may vary according to classification, with A items requiring the most accurate record keeping.

Chapter IV Summary

Time inventory management is now faced with the defects.The advent, through altruism or legislation, of environmental management has added a new dimension to inventory management-reverse supply chain logistics. Environmental management has expanded the number of inventory types that firms have to coordinate. In addition to raw materials, work-in-process, finished goods, and MRO goods, firms now have to deal with post-consumer items such as scrap, returned goods, reusable or recyclable containers, and any number of items that require repair, reuse, recycling, or secondary use in another product. Retailers have the same type problems dealing with inventory that has been returned due to defective material or manufacture, poor fit, finish, or color, or outright "I changed my mind" responses from customers.
Finally, supply chain management has had a considerable impact on inventory management. Instead of managing one's inventory to maximize profit and minimize cost for the individual firm, today's firm has to make inventory decisions that benefit the entire supply chain.

References
[1] D. Bertsekas. Dynamic Programming and Optimal Control, (Volumes
1 and 2). Athena Scientific, 2005.
[2] A. Burnetas and P. Ritchken. Option pricing with downward-sloping
demand curves: The case of supply chain options. Management Science, 51(4):566–580, 2005.
[3] F. Chen and M. Parlar. Value of a put option to the risk-averse
newsvendor. IIE Transactions, 39(5):481–500, 2007.
[4] J. Cox, S. Ross, and M. Rubinstein. Option Pricing: A Simplified
Approach'. International Library of Critical Writings in Economics,
143:461–495, 2002.
[5] R. Levine and S. Zervos. Stock markets, banks, and economic growth.
American Economic Review, 88(3):537–58, June 1998.
[6] E. L. Porteus. Foundations of Stochastic Inventory Theory. Stanford
University Press, Stanford, 2002.
[7] J. Primbs. Dynamic hedging of basket options under proportional
transaction costs using receding horizon control. Preprint, 2007.

Floyd D. Hedrick, Library of Congress, Washington, D.C.
Editor: Jeannette Budding, Communications Manager
National Association of Purchasing Management

库存管理
摘要

库存管理或库存控制，是为了平衡库存的需要和要求，有必要从降低成本获得和持有的库存造成的。有一些企业或学校的思想管理都不尽相同，这些将得到解决。但首先我们提出了一个基础，以方便读者的理解库存和其功能 。
库存管理简而言之就是存货的管理，存货作为一项重要的流动资产，它的存在势必占用大量的流动资金。一般情况下，存货占工业企业总资产的30%左右，商业流通企业的则更高，其管理利用情况如何，直接关系到企业的资金占用水平以及资产运作效率。因此，一个企业若要保持较高的盈利能力，应当十分重视存货的管理。在不同的存货管理水平下，企业的平均资金占用水平差别是很大的。通过实施正确的存货管理方法，来降低企业的平均资金占用水平，提高存货的流转速度和总资产周转率，才能最终提高企业的经济效益。

关键词：库存；管理

第一章 库存的定义

库存数量或者是某些目的或用途（这个词也可以用作动词，意思是把库存或库存的数量在所有商品）持有的商品商店。库存可能会保持“内部”，在该处所或附近即时使用的意义，或者它可能是一个遥远举行
仓库或配送中心供日后使用。随着公司的异常利用刚刚在时间的方法，往往不是中，“库存”意味着商品储存量超过所需要的公司，在当前时间功能（例如，在未来数小时）。

第二章 库存管理的意义
2.1 保持清单
一个公司持有更多的存货比目前要确保公司的运作似乎显得更为重要？以下是为什么要维护存货“过剩”原因列表。
Table 1

January
February
March
April
May
June
Demand
50
50
0
100
200
200
Produce
100
100
100
100
100
100
Month-end inventory
50
100
200
200
100
0

Table1一个企业1-6月份的需求、生产、月末结存情况

2.2 满足需求
为了使零售商继续经营，他们必须对我们的产品，客户手头上的资料，以及仓库里面的存存货必须有所了解，当顾客想用他们时，如果没有，零售商将不得不回到原来的产品。如果这些客户可以从其他来源更好的供应商，他们就可以选择的作比较，使原来的零售商以应付需求后（通过回订单）。因此，在许多情况下，如果没有一个良好的库存，销售是永远失去了
2.3 保持工作的顺利
一个制造商必须具备一定的购买物品（原材料，零部件或部件）能力，以及制造出自己的产品的能力。在许许多多的生产环节中往往创新突破的只有
一个项目，这个项目不仅可以改变你从其他的渠道获得产品，而且还让你的企业获得更高的知名度与利润。
连续相关的操作之间的库存也有助于解决整个行动的依赖。在工作中心的机器往往是根据工人提供的部分工作依赖于它。如果一个工作中心的机器在工作中停止，那么所有的后续工作将无法进行，则必定会影响工作的稳定性。如果一个工作在制造库存是每个工作中心之间，那么每一台机器可以在有限时间内保持其运作，希望恢复到原来的操作中心保持供应。
2.4 节省时间
交货期是时间之间的命令（一个采购订单或生产订单发出到店或工厂车间）和实际接收的货物摆放是有一定的间隔。
如果供应商（外部公司或内部部门或植物）不能按要求提供所需商品，然后在客户端企业必须保持一个必要的商品库存。前置时间越长，规模较大的商品量的企业必须进行库存管理。保持好企业的存货供应充足。
一个刚刚实行（JIT）的制造公司，如在士麦那，田纳西州的日产，能保持极低的库存水平。日产汽车座位上需要交付高达18次之多每天。然而，钢厂可能有一个准备时间长达三个月。这意味着，一个公司，使用在工厂生产的订单，必须在他们需要至少提前三个月钢铁。为了保持其业务运行的同时，一个三个月的钢铁需求对现有库存是必要的。
2.5 数量优惠
通常公司都会给予价格折扣时购买大量的好。在目前需要什么是多余的库存来满足需求，这也是很多企业在降低产品成本的原因。但是，如果折扣足以抵消额外的持有成本作为多余的库存而产生的，决定购买的大量使用是合理的。
2.6 平滑要求
有时候，库存是用来平滑市场需求的地方，是有点古怪的需求要求。考虑需求预测和生产进度表1所述。
同时必须得注意的是如何使用的库存使得公司能够保持稳定的输出率（从而避免了新的招聘和培训人员的费用），从而建立在预期的需求增加库存。事实上，这通常被称为预期库存。从本质上讲，存货的使用使企业移动需求的要求，从而平滑的需求。

第三章 控制库存量

库存还可以用来作为打击价格上涨和通货膨胀的手段。销售人员经常打电话给采购商协商提高价格前不久生效。这使买方有机会购买材料，在目前需要在一个多余的价格低。如果买方价格上涨之后才发生的就不算是控制库存量。
某个公司携带数百甚至不同的零件编号，可面对成千上万的监测各部分数量的库存水平不可能完成的任务。为了促进这一点，许多公司使用ABC办法。 ABC分析是基于帕累托分析，也为“80/20”规则而闻名。 80/20来自帕累托的发现，百分之二十的民众拥有百分之八十的财富。从库存角度看，可以重申正是如此：约百分20之代表所有库存物品的库存成本的百分之80。因此，公司可以控制的监测和控制其库存的百分20之百分之80的库存成本。但是，它必须是正确的百分之二十。
排名前20的公司最昂贵的项目占百分之20的称为“A”的项目（这应该是近似代表总数的百分之80库存成本）。非常便宜的物品或有低需求被称为的“C”与“B”的A和C之间的物品掉落物品物品。该百分比可能会随每个企业的不同而不同，但B项目通常约占百分之三十的项目，总库存成本的百分之十五。 C项目一般占所有库存物品的百分之五十，但只有大约百分之五的费用。
通过划分为A，B或C各存货项目的公司可以决定的资源（时间，精力和金钱）奉献给每一个项目。通常这意味着该公司的项目非常密切监视，但可以在B和C项定期检查（例如，每月为B项和C项季刊）。
另一种控制方法相关的ABC的概念是循环计数。循环计数是用来代替传统的一次的为期三年的”盘点公司关闭了在很短的时间内和物理计算，试图调和他们的库存记录任何可能出现的差异所有库存资产。当使用周期计算，公司不断进行实物计数，但不是总库存。
一个公司可能算一个身体的某一部分厂房或仓库，完成后移动到其他章节，直到整个设施计算在内。那么过程又重新开始。
该公司也可以选择数着一个项目，则B项，最后在C项。当然，计数频率将随每个项目的分类。换言之，一个项目可能被计算每月，每季B项和C项年度。此外，存货记录的准确性可能会有所不同要求进行分类，以A级要求最准确的记录保存项目。

第四章 总结

面对着现时段的库存管理的缺陷，期待着未来存货管理的到来，通过利他主义或法律环境管理，又增加了一个新的层面，库存管理，逆向供应链物流。环境管理，扩大了公司的存货类型必须协调的数目。除了原材料，在产品，产成品，商品和维修，公司现在必须处理后的消费项目，如废弃，退货，可重复使用或可回收容器，以及任何需要维修的项目的数量，再利用，再循环，或在其他产品的二次利用。零售商是同一类型的问题与库存已返回因材料或制造缺陷，或直接交易“改变了我们的库存环境，不过这些都可以从客户的反应上能反映出企业存货管理存在的一些问题。
最后，供应链管理，已对库存管理产生重大影响。不仅是管理自己的库存，而且以利润最大化和尽量减少单个企业的成本，今天的公司必须做出库存决策，造福于整个供应链。

参考文献
[1] D. Bertsekas. Dynamic Programming and Optimal Control, (Volumes
1 and 2). Athena Scientific, 2005.
[2] A. Burnetas and P. Ritchken. Option pricing with downward-sloping
demand curves: The case of supply chain options. Management Science, 51(4):566–580, 2005.
[3] F. Chen and M. Parlar. Value of a put option to the risk-averse
newsvendor. IIE Transactions, 39(5):481–500, 2007.
[4] J. Cox, S. Ross, and M. Rubinstein. Option Pricing: A Simplified
Approach'. International Library of Critical