Планирование цепей поставок в условиях риска с исполь-зованием математического программирования и имитационного моделирования
This paper proposes a risk-aware approach to tactical supply chain planning based on integration of mathematical programming and simulation. A prototype planning system implementing this ap-proach is described. The prototype is developed using Anylogic simulation software and an open source mixed integer optimization tool – GNU Linear Programming Kit (GLPK)
This volume contains a selection of contributions from the "First International Conference in Network Analysis," held at the University of Florida, Gainesville, on December 14-16, 2011. The remarkable diversity of fields that take advantage of Network Analysis makes the endeavor of gathering up-to-date material in a single compilation a useful, yet very difficult, task. The purpose of this volume is to overcome this difficulty by collecting the major results found by the participants and combining them in one easily accessible compilation.
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.
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.
The article shows that Supply Chain Management is an active organization and a current mobilization of value chain to raise contracting parties’ competitiveness. The author analyzes three main groups of decisions (stages in strategic supply chain planning): Supply Chain Design (SCD), Supply Chain Planning (SCP), Supply Chain Operations (SCO). A general outline of strategic decisions realization in supply chains based on a successive principle is suggested: understanding a customer and vagueness of a supply chain; understanding supply chain opportunities; achieving strategic conformity. The author determines areas of strategic conformity in two spectrums of a coordinate: an assumed vagueness of demand and “reactivity/effectiveness” balance of supply chains.
In the article are esteemed assigning and main capabilities of the subsystem of the analysis and maintenance of thermal values of designs of radio electronic means ASONIKA-T, and also principles of simulation of thermal processes in designs with the help of the subsystem ASONIKA-T. The example of simulation of thermal processes in a standard design is adduced.