Компьютерный тренажер для обучения методам управления запасами в эшелонированных логистических сетях
It is developed and presented an approach to inventory management EOQ-model optimization in this paper taking into the deferrals provided for the order cost payments. They summarize the results for the traditional EOQ-models taking into account the deferrals of payments which relate to payment of the batch of goods, with the payment of storage costs, and of the delivery costs payment. Presented modifications of EOQ-formulas will allow for managers to while considering the above features also to take into account he specificity costs of storage charging, in the form of rent, and for the used place on stock, to improve the decisions on the organization of the supply chain quality.
The paper deals with an investigation of relief formation in Europa's surface. Jupiter's satellite Europa is close in size to the Moon. Its surface is covered with a layer of ice crust of thickness 10-30 km. Europa's surface is of large interest, because under the ice crust there is an ocean of liquid water creating conditions for possible life. The entire ice surface of the satellite is covered with a system of bands, valleys, and ridges. These structures are explained by the fact, that the ice surface is rather mobile and it was repeatedly broken from internal stresses and large-scale tectonic processes. The analysis performed showed that compressing, extending, shearing and bending stresses can influence some arbitrarily separated section of Europe's ice surface. The computer simulation with a finite element method (FEM) was performed to see, what types of defects could arise from such effects. The heterogeneity of the satellite's ice cover in thickness, density and temperature was taking into account during the simulation. The calculations, carried out for the cross-section of a thawed ice structure's area, have shown that, the most dangerous, from the crack formation viewpoint, is the shear stress at loading application angles of ±90°. Using models of thawed ice patches in the distributed field of temperatures, the effect of mechanical gravitation-tidal forces on the formation of surface defects on Europa was studied. It is shown that fractures and cracks can have various forms depending on the stress-strained state arising in their vicinity. The formation of such defects is caused by the chaotic set of many factors, mechanic and temperature ones predominantly. Copyright © 2013 by the International Astronautical Federation. All rights reserved.
The article presents a special modification of the EOQ-formula for a diversified EOQ-model of inventory management with account to specifics of lot deliveries. It will allow managers to determine the optimal parameters of the inventory management strategy if it is required to take into account the following features: 1) the possibility of order payment deferral; 2) time value of money at cashflow modelling 3) incomes specifics, when the proceeds come with a delay 4) specificity of storage costs payment (in form of rent or by the occupied storage space). In addition, the article specifies some options related to the possibility of using such a formula if it is necessary to additionally take into account: a) the restriction on the allowable length of the delay in payment of goods, so that the point of receipt of the proceeds did not exceed the corresponding reorder interval duration (on average); b) the vehicle capacity. The presented research materials on optimization of supplies will allow managers to estimate the effect of permissible delays in order payments, delays in receipt of proceeds, and the factor of vehicle capacity on the parameters of the optimal strategy of inventory management. The procedures of EOQ formula modification for inventory management systems are performed in relation to interesting and business-relevant models of this type that correspond to efficient deliveries, where these delays allow to make order payments from revenue at reordering intervals.
Mathematical and computer simulation of economic processes.
Nowadays simulation modeling is applied for solving a wide range of problems. There are simulations which require significant performance and time resources. To decrease overall simulation time a model can be converted to a distributed system and executed on a computer network. The goal of this project is to create a library enabling clear and rapid development parallel discrete event models in AnyLogic. The library is aimed for professionals in computer simulation and helps to reduce code amount. The project includes a research on different synchronization algorithms. In this paper we present techniques which can be used in creating distributed models. We present comparison of a single threaded model with a distributed model implementing optimistic algorithm. The comparison shows a significant improvement in wallclock time achieved by separating the model into independent submodels with minimal communications.
The results concern roll pass design for rolling a round bar of a 20mm diameter from a 55mm diameter input. Concerning materials, this roll pass design must cover a wide range of steels, from low-carbon micro-alloyed steels to stainless steels. The roll pass design proposal takes into consideration lower plasticity of certain steels. The comparison was enabled by suggesting two roll pass designs. The classical oval-round roll pass design, where the maximum extension coefficient is set to 1.55 in oval and 1.22 in round grooves. The second roll pass design uses a combination of smooth part of the roll (curves) and round roll passes. Distribution of the extension coefficient in individual passes is similar to that of oval-round series. The paper also compares values of energy-force parameters calculated analytically using the method of finite elements. If we compare the distribution of temperature, stress and size of the grain, it is proved that the oval-round roll pass designs are the best as far as the balanced distribution of the above-mentioned values is concerned. The roll pas design combining smooth part of the roll with a round part does not achieve such balance. However, its advantage lies in far lower requirement for the needed length of the working part of the roll. Five passes are carried out on the smooth part of the roll, which considerably cuts down the required length of the roll body. Therefore it is this variant that will be used in the laboratory of wire rolling created within the project RMSTC.