Inventory management models for businesses. Inventory management models What does the inventory management model include?
CLASSIFICATION OF MATERIAL RESERVES
Stock- Form of material flow. If the entire logistics lance with which the material flow collapses, working like one mechanical conveyor, the cleaning hour could be reduced to zero and appear as reserves. However, in real life this is not possible.
The material flow from the beginning to the end of the operation can accumulate like a stock of any kind of dealer. Therefore, the reserves of cheese, materials, ready-made vegetables, etc. are divided. bud. All stocks can be divided into the following groupies: virobnichi, commodity. The leather, by its nature, is divided into groups according to its defined function: current, insurance, seasonal.
Meta-creation of organic reserves- Ensuring the uninterrupted production process.
Inventories– stocks of finished products at pharmaceutical enterprises, stocks of wholesale and dispensary trade enterprises, as well as stocks at dosage. Current stocks- What is important is the large number of industrial reserves. Such reserves will ensure the uninterrupted production and trade processes between goods supplies. Insurance stocks Designed for the provision of material and commodity resources in various non-transferable situations: control over the frequency and volume of supplies; neperedbachuvane zrostannya drink. Seasonal stocks They acknowledge the seasonal nature of the production (farm products). Maximum reserve– the value of the reserve, economically complementary to this system. The threshold level of the vikory stock is determined at the moment of the agreement of the upcoming parties. The current stock can be maintained at any time with the maximum stock, trade level and guarantee (insurance) stock.
The logistics inventory management system is designed to ensure uninterrupted production. The implementation of this goal is achieved by the highest levels of upcoming tasks: - the flow level of inventory in warehouses; depending on the size of the guarantee (insurance) stock; resolution of the size of the contract; The time interval between orders is determined.
Is scurrying two main models of inventory management system: model with a fixed contractual agreement (Q-model); model with a fixed period between transactions (P-model). Bathroom systems are fixed in size. With a controlled Q-model, the final order for delivery occurs at the moment when the stock of material decreases to a threshold level. This may happen, whatever the matter, and lie down due to the obligation of living. This system provides continuous control over stock levels. The Q-model is recommended to be stocked with reserves of expensive resources, which will ensure the lowest average procurement cost. However, this model is characterized by high maintenance complexity, so for less expensive objects a system with a fixed hour between orders is preferred. Inventory management system with a fixed period of time between orders. When managing inventory R-models of placement of draft preparations take place through a later singing period. R- the model for calculating surplus stock will only take place after the end of the control period.
The P-model has a larger reserve, and the remaining resources can be exhausted before the actual delivery through a fixing interval.
30. RULE 80–20. ABC ANALYSIS. XYZ ANALYSIS
Rule 80–20 use for structuring inventories, so that in order to see the nomenclature of these inventories, the optimization of which may be carried out in the first place: 20% of inventories account for approximately 80% of current sales or sales dynamics, and 80% of stocks – 20% of sales or sales obligations. The importance of LAN analysis based on the 80–20 rule is that when it is carried out, the entire range of inventories is divided into three groups, and sometimes not into two.
Most of the time, the product range of the products is wide, so modeling and analysis of the skin position is impossible. To simplify the process, carry out ABC-analysis, On this basis, all resources are divided into the following groups: L- High vartisny obsyag; U- Pomerny vartisny obsyag; Z- Low vartisny obsyag. To classify reserves by significance (LAN analysis), the part of the cutaneous grade of the reserves is determined, and they are arranged in decreasing order. Then group A include approximately 20% of the first items in the ordered list, which can be 75–80% of the total inventory. U group U include approximately 30% of positions, part of the range of which should be up to 70%. U group Z include positions that are lost, approximately 50%. The purpose of these procedures is to strengthen the current positions from non-net ones.
This method has the greatest effect in those who are connected with method XYZ This makes it possible to develop a classification of the same inventory nomenclature, as well as depending on the dynamics of their production. The grouping of resources in the XVZ analysis is based on the order of the increase in the coefficient of variation in consumption of the product during the last period of time, which is allocated for the skin item in the assortment:
de Xi- The value of the drink according to the assessed position; X- average quarterly value; P- Number of quarters.
Before categories X contribute resources with a variation coefficient of less than 10%. The stench is transferred, characterized by a stable growth rate. Category Y – these resources, the coefficient of variation which changes in the progressive dynamics from 10 to 25%. Category resources Z are recorded irregularly, the accuracy of forecasting is low, and the coefficient of variation is over 25%.
Based on the results of stagnation ABC-і XYZ- Analysis methods reveal 9 groups of reserves, from which the company can develop its own management options. Groupy AH, AYі AZ demand the greatest respect. For them, a model with a fixed size of the order is put in place, the optimal size of the order is insured, and the technology of “just-in-line” production is developed. For SG group resources, СYі СZ Simpler planning methods are used, and the functions of controlling them are, as a rule, transferred to the lower arms of the flywheel.
The inventory management model can be based on two aspects: how many products to stock and how many to stock. In fact, the number of inventory management models is significant, most of which rely on a variety of mathematical tools - from simple analysis schemes to complex mathematical programming algorithms. This phenomenon is explained by the different nature of the waste of products, which can be deterministic (reliable) or homogeneous. In its own way, the determination of the drink can be static, if the intensity of the reaction does not change over time, or dynamic, if the actual drink changes over time. A homogeneous drink can be stationary, if the thickness of the homogeneity of the drink does not change over time, and non-stationary, if the function of the thickness of the homogeneous drink changes over time.
The main features of the classification of inventory management models are: consumption, inventory replenishment parameters, expenditure associated with the formation and maintenance of inventories, exchange and management strategy. It is necessary to distinguish between deterministic and stochastic (virtuous) inventory management models - due to the influx of temporary officials on the parameters of the management system. If we want one parameter to be a variable value (process), the model will be stochastic, otherwise deterministic.
In real minds, episodes of deterministic statistical power rarely occur. Such an attack can be seen as the simplest one. So, for example, if you want to rely on such mass production products as bread, you can change from one day to the next, but the changes may be so insignificant that the assumption of staticity in the drink does not interfere with its effectiveness.
The most accurate character of the popu can be described in the appearance of incredibly non-stationary divisions. However, from a mathematical point of view, the model significantly collapses, especially with an increased period of time to be viewed. Figure 4 illustrates the increase in mathematical complexity of the inventory management model during the transition from a deterministic static supply to a globally consistent stationary supply.
Due to the nature of the products consumed in the case-by-case model of inventory management, it is necessary to hire other officials:
- 1) contract terms, which is the hour interval between the moment of submission of the contract and the arrival of the purchased products at the co-worker’s address. This interval may be stable or episodic in nature;
- 2) the process of replenishing the stock, which can be migrating (for example, in the case of properly collected products via transport) or constant (for example, in the case of proper products through pipelines or from one’s own workshops);
- 3) the period during which the regulation of the stock level takes place. It depends on the time at which it is possible to reliably predict, perhaps at the end or indefinitely;
- 4) the number of mutually dependent points for saving stocks;
- 5) the number of types of products, if there is an essential balance between different types of products when they are stored in one storage area;
- 6) the availability of exchanges for circulating goods and warehouse space for the preservation of products that are subject to foreign exchange and transit standards, etc. It is extremely important to establish a formalized inventory management model to accommodate all the different types of minds that exist in real systems. Although I decided to try to obtain a universal model, it was unlikely that it would turn out to be analytically clear.
Next we will take a closer look at two models. One of them is single-product, and the other includes the influx of several types of products that “compete.” An important official looks at the formulation and resolution of the task and is also a type of function of expenditures. Various solution methods are being explored that include the classic optimization scheme, linear and dynamic programming.
- 1) Single-product inventory management model - a model of the simplest type, which is characterized by constant supply, constant replenishment of stock and constant shortage. This model can be used in the following typical situations:
- - replacement of lighting lamps in the building;
- - supply of such stationery products as paper, notepads and olives by a great company;
- - selection of various industrial components, such as nuts and bolts;
- - Consolidation of basic food products (for example, bread and milk).
Baby 5 shows a change equal to the reserve of an hour. It is transferred so that the intensity of the drink (per hour) reaches the same level D. The highest level of stock is available at the time of delivery according to the size q(it is transferred that the delivery backlog is a given constant.) The stock level reaches zero according to q/D one hour after removing the size order q.
The smaller size of contract q Thus, it is more often necessary to introduce new agreements. On the other hand, due to the larger size of the reserve, the reserve level moves, otherwise the reserve is placed lower (Figure 6). So, since the amount of money that is being saved depends on the frequency of placement, the amount of q is chosen to ensure balance between the two types of expenditures. This is the basis of a consistent model of inventory management.
Let's go C O- spend on the preparation of the contract, which will take place immediately when it is placed and left, which will be spent on saving the unit of the contract in one hour of equal C h Well, spend the sum in one hour TC as a function q can be seen at a glance:
TC= Spend on order processing in one hour + Spend on saving inventory in one hour
As can be seen from baby 5, the cycle of the roc of the agreement is trivial t 0 =q/D and the average level of the stock is higher q/2.
Optimal values q come out as a legacy of minimization TC By q. In such a manner, at the lower end, q- uninterrupted change, perhaps:
The optimal value for the size of the contract is determined by the following expression:
Formula (3) may be called Wilson's formula of economic size. The optimal strategy of the model conveys the intention q wholesale units of products through the skin
t 0 wholesale =q wholesale /D
one hour. Optimal spending TC wholesale otrimani way without a middle substitution add up.
Most real situations are based on the positive term of final agreement (time delay) L from the moment of placing the order until the effective delivery. The strategy of placing the wording at the pointing model can indicate the point of updating the wording. Malyunok 7 illustrates the fall when the point of renewal of the contract is subject to compression L One hour after the post. For practical purposes, this information can simply be reversed by identifying the inventory renewal point through the inventory level, which indicates the inventory renewal point. In practice, this is achieved by continuously monitoring the level of stock until the delivery point is reached. Perhaps, the model of economical size of procurement is also called the model of continuous control of the procurement process. It should be noted that from the analysis of the minds of the stabilization of the system of the terminology L you can take less cycle time in the future t 0 wholesale .
The assumptions adopted from the above-mentioned models can be similar to some real minds as a result of the drink’s peaceful character. In fact, having expanded the proximity of the method, which preserves the simplicity of the model of economical obligatory registration, the instantaneous peace of mind protects the universal character of the popu. The idea of the method is extremely simple. It transfers the creation of a permanent (stationary) buffer stock along the entire planning horizon. The size of the reserve is determined in such a way that the possibility of replenishing the reserve throughout the contracting period L did not exceed the predetermined value.
In some cases, the amount of money spent on saving products is significant, even though the amount of money spent on stock is limited over a short period of time. You can create an inventory management model in which regular periods are transferred during which there is no stock.
There are two possible outcomes. The first one will end up with products that are out of stock and become dissatisfied. Kerivnitstvo can praise the decision to reduce the level of stocks of large-sized products that are stored in warehouses. This decision will lead to the fact that there will be no reserves of this product in the skin cycle for several days. Through a reduction in sales obligations, the singing sense of spending the trust of clients appears to be spent. The cost of production will be affected by the costs and the amount of savings captured due to the availability of product inventories. Another option may be the fact that the purchased products are accepted from the warehouse and the buyer in the world receives the purchased products from the warehouse. Whenever a business incurs expenses associated with the support of the procurement system, this is reflected in the amount of savings generated by the conservation of inventories. The main difference between the two described phenomena is that in the first of them, after the withdrawal of new supplies, the purchasers' demands do not end, and the maximum level of inventories is maintained with the size of the purchases made. In another case, part of the products from the new supply is due to customer satisfaction, so the maximum level of inventory is the difference between the size of the order and the maximum supply, which is due to the lack of inventory.
To decompose the average stock of reserves, we will consider one cycle of the stock of trivalist Trocks. Let the available supply be acquired by the extension of t1 rocks, and by the extension of t2 rocks the daily reserve:
During the period of depletion of stock t 1 the average price of the stock is old (q - S)/2. Well, it’s being saved in warehouses (q - S)/2 units of production in the middle period t 1 .
The result is negligible (q - S)t/2 units of products. For a part of the cycle, then. for an hour t 2 0 units of products are stored in warehouses; as a result, it is eliminated 0 H t 2 units of products.
It is necessary to know the average number of units of production that is kept in stock throughout the entire cycle T.
Also, the average number of units of products that are kept in stock over the course of the stock cycle becomes.
Now we can calculate the rate of growth of reserves D (unit of production per river) as follows:
D = (q - S)/t 1
D = q/T.
t 1 = (q-S)/Dі T = q/D.
Submitting known relationships for t 1 i T The formula for the average level of reserves over one cycle is eliminated:
Thus, the average size of the deficit is equal to:
Based on this, you can find the optimal size of the contract and the maximum size of the deficit:
If we look at the first phase, in which the clients' agreements do not end, the analysis procedure will be similar to the established algorithm, except that the maximum amount of reserves will be equal q. So you can just get a replacement (q - S) on q, a q- on (q+S), substituting the values of the formula for the breakdown of the average level of reserves and the average size of the deficit. In this case, the zealous changeable vartosti will look like this:
As in the first instance, having established the operation of differentiation by parts, it can be shown that the optimal size of the proposal is determined by the following formula:
and the maximum size of the deficit becomes:
2) A static product model with interconnected warehouse spaces. This model is intended for storage systems that include several types of products that are stored in one warehouse in a limited area. This concept means the interconnections between different types of products and can be included in the model as an exchange.
Let's go A- maximum permissible storage area for n types of products; it is acceptable that a is the area required to save one product i In view, then the exchange for the needs of the warehouse premises arises in appearance:
It is acceptable that the supply of skin-type products will be replenished by Mittev and daily price reductions. It is acceptable that shortages are not allowed. Let's go D i , C Oi ta C hi- Intensity of consumption, expenditure on processing orders and expenditure on saving one product per hour for i This type of product is consistent. The total costs for skin products, in essence, will be the same as for an equivalent single-product model. In this manner, the misery that is seen may appear to be minimized.
for everyone i.
The most advanced approach is the Lagrange multiplier method. However, first of all to use this method, it is necessary to establish what the purpose of the exchange is, having verified the importance of the exchange in the warehouse area for optimal
unbounded plant. As soon as the exchange is concluded, it is supernatural, and it can be seized. The difference is that it doesn’t mean anything. In this case, it is necessary to find new optimal values of qi, which satisfies the exchange in the warehouse area in the appearance of equality. This result is achieved by a per-day function of the form:
de, (<0) - множитель Лагранжа.
Optimal values q i And you can find out by adjusting the corresponding differences to zero, which gives:
From another level, there is a trace that can significantly satisfy the area of the warehouse as equal.
From the first, jealousy grows that:
Dear, what to keep below the optimal value * multiplier In addition, when * =0 value - the tasks are released without interchange.
Significance * can be determined by systematic testing and testing. Remnants of the objectives of the main task of minimization<0, то при последовательной проверке отрицательных значений найденное значение * instantly significant value q op t, which satisfy the given exchange in the appearance of equality. In this manner, as a result of the appointment * automatically display values q op T.
In addition to the list of inventory management models in logistics, there are also different systems that are divided into subsystems and have a variety of options. When choosing an inventory management model, one of the major factors is the nature of the supply. Just like that
Following are the main indicators of the government's financial activity of the enterprise, the characteristics of the manufactured/sold products and many other factors.
2.3.1. Standardization of stock
Inventory management has two main tasks:
1) paying for the necessary supplies, then. normalize the reserve and frequency of this increase;
2) the creation of a system to control the actual size of the stock and its current additions to the established norm.
Stock norm– the minimum level of inventory that may be in the warehouse of the enterprise to ensure uninterrupted supply of production or sale of goods. To determine inventory standards, three groups of methods are used: heuristic methods, methods of technical and economic development, and economic and mathematical methods.
Heuristic methods transmit detailed information to traders who determine the market value for the previous period, analyze the market and make decisions about minimally necessary stocks, based on a significant value on the subjective side I will drink smart trends from development. As a specialist, you can act as a business operator who constantly maintains the required standardization of inventories. In this case, the method of solving a problem is called pre-trace-statistical. As a result, several fakists are tested, their subjective assessments of the situation are analyzed using a special algorithm, checked for imperfection and transformed into a residual solution that is close to optimal. This method is called the method expert assessments.
Method of technical and economic developments lies in the aggregate stock section depending on the purpose of the group, for example, nomenclature or assortment positions. Then, for these groups, it is necessary to obtain insurance, current and seasonal reserves. From these regions there may also be divisions into other warehouses, for example, an insurance stock for the event of a disruption in supply, or an insurance stock for the event of an increase in food, etc. Method of technical and economic developments allows you to accurately determine the required amount of reserves, but it turns out to be very difficult. This approach is also used in the MRP system (section 7.5.2).
Economic and mathematical methods allow you to determine the stock norm on the basis of the required mathematical models of ultrasound, or for additional help extrapolation methods forecast future reserves based on the rate of change and trends in the development of reserves in the previous period.
The effectiveness of the work of ultrasound systems depends a lot on how much water will be transferred to the resource and, therefore, how correctly the standardization will be carried out. Tse dosit folded zavdannya. These types of pits are distinguished by the level of importance and immutability of their value (Fig. 2.3)
Fig.2.3. Classification of drink types
Determinations will come just home from afar, to the front of the line Have a delicious drink. At static Type of consumption, the intensity of the resource loss becomes unchanged in hours, when dynamic The type of drinking intensity changes over time. At stationary The type of drinker's function of intensity and intensity is unchanged in hours, and when non-stationary – The function of the power and strength of the drink changes over time.
Behind the sign the dzherel viniknenya will drink to fall on the independent and fallow. Independent will drink - drink, which consists of a large number of people living in warehouses, whose skins have different needs than others. Zalezhny will drink It is possible to place, if the vicorist’s manufacturer contains a number of components for the preparation of GP, apply to the skin from the components of the dressings one by one and lie in the vicinity of the preparation plan for the preparation of GP.
With the independent type of drink, the approach is taken into account, whose reserves do not correspond with the production plans, and that may be kept high in order to satisfy any possible drink. These reserves decrease during the time of production, but will never be replenished again. The underlying dynamics of changes in reserves during non-stale and stale drinking is clearly shown in Fig. 2.4 (a) and (b).
Fig.2.4. The dynamics of changes in reserves
for stale and non-stale drinking
If you have a stale drink, you may need to take a victorious approach MRP – materials consumption planning(material requirements planning) (div. 7.5.2). The essence of this approach lies in the breakdown of requirements for all types of materials, raw materials, components, parts necessary for the production of a leather product according to the production plan for the necessary service, and the supply of such orders for delivery. Have rozrakhunkah vikoristovuyutsya Specification sheet– ordering the transfer of all warehouses, the necessary selection of a specific product.
Another way to plan is to approach "exactly in lines"(just in time) or JIT (div. clause 7.5.4). PurposeJIT- Ensuring the delivery of materials without delay until the end of specific operations, which is why the stock is actually depleted. In Fig. 2.5 presents the obligations of reserves for various approaches to planning.
Small 2.5. Inventory level for different approaches to inventory management
The reason for the decrease in the level of inventories, shown in Fig. 2.5 (b) and (c), there is greater coordination between the supply to the market and the supply of the enterprise to the materials that are delivered to the customers.
2.3.2. Static inventory management models
The optimal batch model has been normalized for the settlement of unconfirmed orders
Input parameters of the model
1) n – intensity of inventory growth [supply/spec.t];
2) l – intensity of procurement production [od.product/od.t];
3) s – spend on saving stock [rub./item. * od.t];
4) d – penalty for shortage [rub./item. * od.t];
5) K – Vitrati zdіysnennya zamovlennya [rub.].
Output parameters of the model
1) Q - size of the contract [single item];
2) t - period of fasting [od. t];
3) - the complexity of the i-th stage of the cycle of changing the stock;
4) L – overhead costs of inventory management per hour, [rub./unit];
5) N – maximum level of warehouse stock [same items];
6) h – maximum level of deficit [od.
This model is based on the assumption that it is a vibrational process, in which, at the first level, a batch of parts with intensity is generated, which are then processed at another level with intensity (Fig. 2.6).
Fig.2.6. Principle diagram of the production process
New applications for a product that survive, accumulate and are inevitably satisfied in the world of new product developments. The cycle of inventory change is divided into 4 stages (Fig. 2.7):
1) t 1 – the harvested product vibrates, the vibrated product accumulates, the stock accumulates;
2) t 2 – the harvested product does not vibrate, the stock decreases ® the stock changes to zero;
3) t 3 – the purchased product is not produced, the supply of daily ® unfilled orders accumulates, the shortage increases;
4).
Fig. 2.7. Graph of inventory change cycles in the established UZ model
z urahuvannyam new applications
Model formulas
; 
; ;
; 
; 
; 
;
The model of the optimal batch of delivery due to the wastage of new orders has been adjusted
This model is characterized by the fact that during the period of t 3 harvests, the product does not accumulate, the stock is daily, the shortage increases, and in the event of which the demand does not accumulate, but is lost (Fig. 2.8). In this case, the penalty for a shortage of a model with the loss of unauthorized applications is greater than that of a model with the loss of unauthorized applications.
Fig. 2.8. Graph of inventory change cycles in the established UZ model
from the waste new applications
Model formulas
; 
;
; ; 
; ; .
The skin from the examined ultrasonic models is subject to several possible ultrasound situations:
1) the product is vibrating (), shortage is allowed () (div. Fig. 2.7, 2.8);
2) the product is purchased (), shortages are allowed ();
3) the product is vibrated (), the deficiency is blocked ();
4) the product is purchased (), the shortage is blocked () – Wilson model(Fig.2.9).
Fig.2.9. Graph of inventory change cycles in the Wilson model
UZ model that provides insurance benefits
This model gives the insurance company the ability to provide a discount to the buyer to add a batch of goods of a certain size. When ordering in larger quantities, on the one hand, there will be a reduction in costs for purchasing and delivery, and on the other hand, there will be an increase in costs for savings. Thus, the optimal size of the contract can change depending on the situation and the availability of reductions. A detailed description of the UZ model, which provides insurance benefits, is provided in paragraph 12.
2.2.3. Dynamic KM systems
In real minds, ultrasonic parameters may change over the course of a given planning period due to the following reasons:
· Changing the intensity is similar to the other;
· Trimming or speeding up delivery;
· Posting an unplanned contract;
· Changes to the actual stock, which leads to incorrect allocation of the size of the order.
Table 2.1 presents the possible inflows that will overcome, that will bring the system to the point of either a shortage of the Ministry of Health or warehouse space. In fact, there may be different types of injections that are overfilled in the right and left sections of Table 2.1.
Table 2.1
Possible developments in the inventory management system
In the descriptions of situations, static KM models do not work, and therefore it is necessary to stagnate dynamic KM models from which adaptation mechanism until the situation changes.
Another feature of static models of KZ, which is unpleasant in the descriptions of minds, is the corresponding criterion for minimizing the total costs of storing stocks and making deliveries. Such a criterion is not meaningful in situations where
· The hour of the viconn's promise is to finish the trival hour;
· Deliveries are often delayed;
· Popit feels the sound of the day;
· Prices for raw materials, raw materials, and other products fluctuate greatly.
In this case, it is inappropriate to rely on diminished reserves. This can lead to the impossibility of uninterrupted service for the resident, which indicates the functioning of the UZ logistics system. In other situations, the optimal procurement procedure will ensure a reduction in costs for saving inventory without sacrificing service costs.
Before main dynamic systems of ultrasound include:
1) a system with a fixed size of the contract;
2) a system with a fixed hour interval between orders.
Ultrasound system with fixed size of contract
The flow of reserves in the system with a fixed size is indicated by graphical representations in Fig. 2.10.
Fig.2.10. Graphic model of the robotic system of ultrasound
with fixed contract size
The threshold level of the stock is insured as it is for the stock, which will be available at the time of delivery to ensure the safety of the safety stock. In the event of any failures in the delivery system, the order will be made as soon as the stock reaches insurance equal. Insurance stock allows you to ensure the need for an hour of maximum possible pre-stitching. The replenishment of the safety stock increases according to the hour of upcoming deliveries. In the event of failures in supplies and the optimal size, the supply stock will increase to maximum bazhanogo equal. In addition to the insurance and threshold maximum reserves, the reserve does not immediately affect the functioning of the system as a whole. This level of stock is indicated by the increase in the demand for space.
The order of setting up the parameters of the inventory management system with a fixed size of the order is in a series of views in Table 2.2.
Table 2.2
Parameters of the ultrasound system based on the fixed size of the contract
|
Input parameters |
Appointment |
|
|
Maximum |
||
|
Delivery rate, K, rub. |
||
|
Output parameters |
Rozrahunok |
|
|
Optimal order size, pcs. |
||
|
Safety stock, pcs. |
||
|
Threshold stock level, pcs. |
||
Necessity peacefulstock in stock In a system with a fixed size, the structure can be seen as its main shortcoming. In addition, this system is not oriented towards the non-disposable malfunctions in communication. The stinks can lead to a deficit country, which may be blocked by the advance of supplies (Fig. 2.11). To correct such a situation, it is necessary to contact the supervisor disposable There is an increased supply requirement to allow you to replenish the supply to the maximum required level.
System of supplying stocks with a fixed hour interval between orders
A graphical model of the robotic ultrasound system with a fixed hour interval between tasks is presented in Fig. 2.12.
Fig.2.11. Graphic model of the robotic ultrasound system with a fixed size of the agreement for the detection of non-disposable delays in supplies
Fig.2.12. Graphic model of the robotic system of ultrasound
with a fixed hour interval between orders
The procedure for setting up the parameters of the inventory supply system at a fixed interval of an hour between the submissions is in Table 2.3. Hour interval between orders (fasting period) start screaming take out the insurance, and then they can correct it. For example, if you have completed a 4-day period, you can apply a period of 5 days in order to submit your application once a week.
Descriptions of the main KM system are based on fixing one of two possible parameters – the size of the order or the hour interval between orders. Aloha for clarity systematic Failures in the established and established main ultrasound systems become ineffective.
Table 2.3
Parameters of the ultrasound system based on a fixed hourly interval
between agreements
|
Input parameters |
Appointment |
|
|
Intensity of growth, pcs./unit. (in case of expansion, rounding to the larger side) |
||
|
Delivery term: , od. |
||
|
Maximum Possible zatrymka in supplies, od. |
||
|
Delivery rate, K, rub. |
||
|
Stock saving amount, s, rub. / (Pieces * Days) |
||
|
Output parameters |
Rozrahunok |
|
|
Delivery period, , od. |
||
|
Safety stock, pcs. |
||
|
Maximum stock, pcs. |
||
|
Volume of orders, Q, pcs. |
||
|
de - current stock of goods that were ordered but not delivered |
||
A wide range of developments of the main ultrasound systems, together with the addition of fundamentally new ideas, will lead to the possibility of forming a large number of other ultrasound systems that represent extremely different benefits.
To the widest modifications The main dynamic systems of ultrasound include:
1) a system with established periodicity for replenishing stocks to a constant level;
2) the “minimum-maximum” system.
The KZ system, based on the established frequency of replenishment of stocks to a constant level
An important feature of the system are those that are divided into two categories:
1) plans Q p, what is served at specified intervals at hour t;
2) additional Q d when stocks in the warehouse are reduced to a threshold level. The need for additional agreements may arise when the pace of development accelerates compared to the plans.
Thus, this system includes a system element with a fixed hour interval between purchases (the frequency of purchase orders is set) and a system element with a fixed size of purchases (the threshold level of inventory is established). In addition to the main systems, it is focused on working with significant kolivannya spozhivannya.
A graphical illustration of the functioning of the US system based on the established frequency of replenishment of stocks to a constant level is shown in Fig. 2.13. The order of breakdown of all parameters of the KM system in a series of views is in Table 2.4.
KM system “minimum-maximum”
Fig.2.13. Graphical model of the robotic management system based on the established frequency of replenishment of inventories to a constant level
Threshold reserve reserve the “minimum-maximum” system has a unique role “ minimal»River. As soon as this period has passed, the agreement is drawn up, otherwise the agreement is not seen. The detection of the threshold level, as well as the appearance of the contract, occurs only through the tasks at the hour interval t.
This system operates with two levels of reserves – minimal(threshold) that maximum and place elements of the system with a fixed interval of hours between orders (constant interval between deliveries) and systems with a fixed size of orders (variable threshold level). The “minimum-maximum” system is focused on the situation when the expenditure on the stock of reserves and the expenditure on registration of agreements is significant, which becomes equal to the expenditure due to a shortage of reserves. A graphical illustration of the functioning of the “minimum-maximum” ultrasonics system is shown in Fig. 2.14. The order of distribution of all powers of this system of ultrasound representations is in Table 2.5.
Table 2.4
Parameters of the US system based on the established frequency of replenishment of inventories to a constant level
Federal state budgetary education for the establishment of high professional education
"Volgograd State Technical University"
Department of Economics and Management
Faculty of Engineering Personnel Training
Inventory management models
Volgograd 2014 r_k
Enter
1. Basic provisions of the theory of inventory management
2. Types of inventory management models
3. The inventory management model for these items has been formalized
4. Wilson model
Visnovok
List of references
Enter
Widely stocked areas, logistics systems and vicoristic stocks. Therefore, in order to undertake important tasks, one must learn; optimal inventory management strategy. As a stock, you can see milk, finished products, components and finished products. Proper inventory management is closely linked to the organization of the purchasing process, both from the production of goods and from finished products.
There is a need for a mother's reserves, which is based on one of these factors:
· Kolivannya drink on goods;
· definition of terms for delivery of goods from the enterprise;
· minds that will require purchasing products in batches;
· Detection of any costs associated with shortages (in stock) or delays in delivery.
In most situations that arise from trade activity, one is wary of the rapid emergence of these factors. Obviously, only in certain situations can businesses pay for the availability of reserves.
1. Basic provisions of the theory of inventory management
The theory of inventory management is important to the youngest students of operations.
The basics of the modern theory of inventory management are setting orders, analyzing factors that contribute to the market, and a way to determine the level of uncertainty in drinking. The developments of the theory include, for example, the following ideas:
· Managing inventories of the same product in an isolated warehouse while fixing supply delays;
· Inventory management during sudden supply delays;
· Management of extensive inventory, etc.
Maximum reserveindicates the level of inventory, which is economically equivalent to this inventory management system. This rhubarb may be overestimated. In some control systems, the maximum supply of vicor is used as a guideline for the breakdown of procurement procedures.
Threshold rhubarbThe stock is determined according to the time of receipt of the draft order.
Current stockIt shows equal reserves at any moment. You can use a maximum reserve, a limit or a safety stock.
Warranty(or insurance) stockpurposes for uninterrupted supply of companions in unfavorable situations.
The inventory management model consists of three blocks:
Sales forecasting block - forecasting the year/day sales of a product;
Inventory control unit – optimization of planning of safety stock, in-line stock, etc. with the established model of inventory management for the leather product category;
Delivery control unit - optimization of delivery planning in the middle of the company’s logistics network with the management of planned sales, production output, the presence of surpluses, transport pressures, various interactions and business rules.
Types of reserves
Understanding of material stock
Reasons for the destruction of material reserves
Concept of material stock.Inventory - this includes raw materials, materials, components, finished products and other material assets that are ready for entry into the process of manufacturing and special production.
The main part of the stocks for the enterprise are production items that are included in the material flow at various stages of its technological processing.
Reasons for the destruction of material reserves.Stocks for business are created for two main reasons:
the inconsistency of one-time obligations;
the gap between the moment of acquiring the material and acquiring it.
The supply of raw materials occurs in most bursts periodically, and their supply is usually continuous and does not occur in the hour of need. Also, ensuring uninterrupted operation of the skin industry creates reserves of essential types of raw materials, materials, finished products, burning and other resources. There are also other reasons that lead to the creation of reserves. Tse – seasonal price variations; disruption of the established delivery schedule (non-transferable reduction in the intensity of the input material flow); the possibility of pumping (untransferred increase in the intensity of the output flow) and others.
Types of material reserves.On the way of transformation of the syrup into the final production and further development of the final production, two main types of reserves are created: production and commodity reserves.
Viral stocks are formed in storage organizations in order to ensure the uninterrupted production process.
Commodity inventories include stocks of finished products at manufacturing enterprises, and supply stocks according to the amount of goods from the delivery person to the customer, then. at wholesale and retail trade enterprises, and at manufacturing organizations, stocks are high. They are necessary for the uninterrupted provision of material resources for their residents.
Viral and commodity stocks are divided into production, preparation, insurance and seasonal:
Accurate stocks are necessary for the business to ensure uninterrupted operation between two deliveries and ensure the ability to produce products in optimally sized batches. This part of the stock is established in the minds of an even and regular supply through the inconsistency of delivery obligations and one-time supply, as well as the delays associated with the flow of materials.
Preparatory stocks are kept in stock to ensure uninterrupted operations during the period necessary to prepare materials prior to delivery and delivery to work sites.
Guaranteed (insurance) reserves of necessary safety equipment for the enterprise in case of possible interruptions in the supply and production process. These additional reserves are used to compensate for the improvement of actual production from the forecasted one, the improvement of actual production from the planned one, and the improvement of actual production from the planned one.
Seasonal stocks are made up of seasonal quantities for production and production. This stock of indications of satisfaction with the forecasted (seasonal) increase in drinking will lead to the current expansion of the enterprise during the emptying period.
2. Types of inventory management models
Regardless of the fact that any inventory management model responds to two main principles (as many as they do), there are a number of models that require a variety of mathematical tools.
This situation is explained by the difference in the output minds. The main basis for the classification of inventory management models is the nature of the purchased products that are stored.
Depending on the nature of this model, inventory management models may
· Determined;
· Imovirnisny.
In its own way, the determinations of the drink can be static, if the intensity of the reaction does not change over time, or dynamic, if the intensity of the drink can change over the course of time.
A smooth drink can be stationary, if the thickness of the drink does not change over time, and non-stationary, if the function of the thickness of the drink changes over time.
The simplest type is the production of deterministic static products.
However, this type of living is practically impossible to achieve very often. The most folding models are non-stationary models.
Due to the nature of the products consumed, individual inventory management models must be taken into account without other officials, for example:
· Vikonannya terms. The severity of the procurement period is either steady or intermittent;
· Inventory replenishment process. Perhaps we will hold a meeting and divide the hour;
· Obviousness of the boundaries of circulating goods, warehouse areas, etc.
3. The inventory management model for these items has been formalized
Securing the needs of government, social and military objects in various material means includes three phases: planning, selection and division. As a rule, at the time of implementation of the supply, the data included as the basis of the application are outdated and the delivery promise does not correspond to actual demand. In order to keep up production in times of shortage of supply, supplies are created in the supply system. The following factors should be used to build up reserves:
Discreteness of deliveries
Vipadkovi Kolivannya
at a drink for the interval between deliveries;
supply obligations;
at trivial intervals between deliveries.
Current changes in the situation:
seasonality of the drink;
seasonality of production;
inflationary pressures;
price increases have been identified.
The listed officials are creating a trend towards increasing reserves.
And, however, a number of considerations are taken to minimize reserves:
fee for physical storage of reserves;
Spend a lot of stock (steaming, drying, stealing);
There are clear changes (the loss of lingering powers as a result of irrevocable processes in the product that is being preserved);
Morally I'm exhausted.
Inventory management is related to the established moments and obligations of ordering for replenishment and distribution of newly arrived batches behind the lower lines of the supply system. The set of rules by which decisions are made is called an inventory management strategy. The search for an optimal strategy is the subject of the theory of inventory management optimization.
With the same strategy, the insurance will lose the variable warehouse function of expenses, as in the choice of strategies, i.e. In many inventory management models, it is possible to ignore most of the costs of the management team (except for the costs of processing deliveries), and to assign a proportional responsibility to the party for the production of inventory, so that the three-valued bucket can fill In a short time it is indicated as a summary drink and must be kept in mind for the organization of delivery.
The mathematical formulation of the knowledge about finding the optimal strategy is based on the situation under investigation. However, the multiplicity of factors involved in insurance allows us to talk about a single model of inventory management. Let us give a clear description, limiting it for simplicity to one warehouse, which allows us to find an intermittent flow of clearly identical applications - applications from companions. Requests are strictly satisfied until their total supply (from the beginning of the planned period) exceeds the initial supply. All events cannot be serviced immediately, so the customer is standing still and recognizes the jams. If you deposit this amount before the post-payment system, you will pay a fine. In some cases, the mine reserve that is saved is replenished from the utility warehouse, the central base, or from industry, and such replenishments are associated with additional expenses. Nareshti, the warehouse will not be spent on saving the lane that is located in New. It is necessary to choose the moment and obligation to renew so that the total amount spent on savings, fines and expenses are minimal. Interchange actions may be applied to the warehouse work. In such cases, there is a minimum amount of money spent.
Thus, the elements of inventory management are:
Posting system;
Drinks on the items;
Possibility of replenishment of reserves;
function vitrat;
obmezhennya;
Inventory management strategy.
Under the delivery system, there is a totality of orders and warehouses, between which, during the delivery operation, the transported mine is processed and saved. There are three options for the wake-up system:
· Decentralized. All warehouses directly serve the residents, and the shortage of one or more warehouses for the decisions of the governing body can be covered with the help of excess stocks in other warehouses.
· Linea. A virobnic lancet is seen and the distribution of buffer stocks is being insured to ensure the readiness of the goods.
· Echelonovana. The skin shortage is covered by the end of the stocks of the warehouse at the highest level.
Spend your savings:
· Proportional to the average level of positive reserves during the period when the positive reserve was established;
· Proportional to the positive surplus at the end of the period;
· Proportional to the maximum reserve;
· Nonlinear functions are one of the most popular predictors.
Inventory management.
Vidi vitrat
The practical implementation of the concept of material flow management is associated with the optimization of total inventories. The criterion for optimizing inventories is wasted expenditure on production and conservation of materials.
In the system of purchasing and saving materials, expenses are divided into the following groups:
vitrati na vikonannya zamovlennya;
direct spending, which is represented by the purchase price;
spend on reducing reserves;
"Eliminate the deficit."
Vitrati na vikonannya zamovlennya related to the placement and postal agreements. Before them, the following statistics are due, such as the development of the development of minds and their preparation until hardening; spend on additional advertising catalogues; vytrati, connected with the control of the viconic agreement and shortened line of their viconic; transport expenses, since the cost of transportation is not included in the cost of the goods; Vitrati on folding and trimming the order.
All of them are recorded in the contract and are not subject to obligation; others, for example, transport and warehouse expenses are directly related to the contract value. The amount of money spent on a written contract includes all types of spending, the amount of which is due to the amount of money that needs to be written. Spend directly are determined by the price of the materials that are purchased and changed in stock as a wholesale reduction to the price that is established with a larger batch size. Spend on increasing reserves are determined by expenses for saving materials and the very fact of the availability of reserves. This group of expenses includes the following types of expenses, such as the maximum amount of capital, investments in stock; spend on warehouse operations and rental fees for the warehouse; exactly spend on the maintenance of warehouses that are located in the production unit; Waste associated with the risk of waste and moral obsolescence of materials, and insurance and tax losses. A decrease in inventories will lead to a change in warehouse costs and operational costs for the reduction of warehouse space. “Waiting on the deficit” means spending that arises from the connection with the exchange of these or other material resources during any period. This group of expenses includes expenses of three types:
inventory management is a model of manufacturing waste associated with a slowdown in the manufacturing process through the lack of necessary materials, as well as the replacement of material with another at a higher cost;
the amount of wasted sales in the event of an unconventional agreement, when the sales manager is transferred to another distributor (in such a situation, the loss of the deficit is considered the same as the loss of the profit);
additional expenditures that arise from time to time on the basis of a new contract.
Standards for warehouse vitrats. Warehouse expenses are enlarged to be insured according to the legal norm, which is the insurance relationship between the permanent and changeable part of expenses. The norm of warehouse receipts is
de N – norm of warehouse vitrates; A is the interest rate on investments in the capital stock; B - the rate of expenditure for saving materials in the warehouse;
de R - spent on saving materials in warehouses for the current period; D – average level of warehouse stock.
4. Wilson model
Mathematical models of inventory management (IM) allow you to know the optimal level of inventory for a given product, which minimizes the total costs of purchasing, processing and delivery, saving goods, and also stocking up on shortages. . The Wilson model is the simplest KZ model and describes the situation of purchasing products from an external supplier, which is characterized by the following assumptions:
· The intensity of growth is a priori known and constant;
· The order is delivered to the warehouse, where the goods are preserved before they are damaged;
· the hour of fasting is a known and constant value;
· skin lesions appear in one party;
· the amount spent on this agreement does not fall short of the amount of the agreement;
· spend on saving stock in proportion to its size;
· Insufficient stock (shortage) is unacceptable.
Input parameters of the Wilson model
) u-intensity (swisdom) compared to the reserve, [od. Comrade / od. t];
) s - Spend saving on stock, [rub./item* item. t];
) K - expenses for the contract, which includes registration and delivery of the contract, [rub.];
) t d - Hour of delivery of the order, [od. t].
Output parameters of the Wilson model
) Q - contract size, [od. Comrade];
) L - spent on keruvannya in reserves per hour, [rub. / od. t];
) t- the period of fasting, then. hour between supplies and deliveries, [od.t];
)h 0- point of agreement, then. the size of the warehouse stock, who needs to submit a request for delivery of the prepared batch, [odd. Comrade].
The cycles of change in the stock level of the Wilson model are graphically presented in Fig. 1. The maximum quantity of products that is in stock is subject to the order quantity Q.
Fig.1 Graph of inventory change cycles in the Wilson model
Wilson model formulas
(11.1)
de Q w - The optimal size of the contract in the Wilson model;
Vitrat graph on the ultrasonic Wilson model of representations in Fig. 2
Small 2. Vitrate schedule based on Wilson’s ultrasound model
Visnovok
Until recently, it was believed that the more reserves a business has, the better. This is true if the business faces problems with material and technical supplies, for the minds, if it is necessary to create significant insurance reserves. However, in modern minds, the problem of scarcity is less acute, and businesses can make highly profitable investments. The ruler is under pressure to create reserves, so that in other cases, expenses will increase or income will change.
survivable popit inventory management model
List of references
1. Blank I.A. Financial management: Basic course. - 2nd view, - K.: Elga, Nika-Center, 2008.
Nerush Yu.M. Logistics: Handbook for universities. - 2nd view. - M: UNITI-DANA, 2007.
Financial management: theory and practice: Pidruchnik. / For ed. Stoyanova E.S. - 2nd type, processed. ta add. - M: View Perspective, 2000.
Afanasenko I.D. Workshop on logistics of delivery: nutrition and dough / Afanasenko I.D., Borisova V.V. - St. Petersburg. : View of St. Petersburg State University of Economics and Economics, 2011. – pp. 131-134 (188 pp.)
http://ua. wikipedia.org -< свободная энциклопедия>
Logistclub.com.ua -< Типы моделей управления запасами>
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The main goal is to ensure an uninterrupted process of production and sale of products while minimizing the total cost of maintaining inventory.
At a glance, management of current assets bring to the production reserves not only raw materials and materials necessary for the production process, but also unfinished production, finished products and goods for resale.
Managing optimal inventory levels
Important food supplies require a large amount of safety stock to deal with unexpected supply disruptions and possible seasonal surges in livestock supplies. It is obvious that insurance reserves will absorb the financial results of industrial activity (for the purpose of freezing assets in stocks), but will ensure the stability and liquidity of the enterprise.
Inventory shortage This is due to the need for production, the decline in implementation obligations, and in some cases there is a need to obtain the necessary materials at protected prices. Finally, there is an under-recovery of possible gains. Inventory scraps are all liquid assets, and their decrease reduces the flow liquidity indicator.
Excess reserves lead to increased costs for their savings, growth, non-removal of possible income through the freezing of financial resources in reserves, costs as a result of physical disposal and obsolescence of reserves
Inventory management
In the case of a steady increase in prices, a more objective assessment of the results can be given by the LIFO method, which smoothes out the influx of inflation to form profits. Also, depending on the time of this method, the amount of surplus and, consequently, the amount of the cash flow changes.
Since at the moment the enterprise is pursuing a policy of minimizing prices and reducing costs, it is entirely necessary to use the FIFO method.
It improves financial indicators (), increasing the availability of surpluses and changing expenses, increasing profits.
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