Ein SIMULA-Modell zur Ereignissimulation von Stadtstraßennetzen

Zusammenfassung Die Grundkonzepte eines semimakroskopischen, stochastischen und ereignisorientierten Simulationsmodells für Stadtstraßennetze werden entwickelt. Dabei liegt das Schwergewicht auf dem Fahrverhaltensmodell, Fahrfolgeverhalten an Kreuzungen und Pulkauflösung. Das Programm wurde in SIMULA geschrieben und kann zur Simulation von Stadtstraßennetzen verwendet werden.

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Summary The fundamental concepts for a semimakroscopic, stochastic and eventoriented simulation model of the traffic in an urban area are developed. Special attention is paid to vehicle movement, queue discharge and platoon dispersion. The program was written in SIMULA and can be used for the simulation of urban networks up to 80 nodes.

     

Elasto-plastic earthquake response of arch dams including fluid–structure interaction by the Lagrangian approach

Elasto-plastic earthquake response of arch dams including fluid–structure interaction by the Lagrangian approach is mainly investigated in this study. To this aim, three-dimensional eight-noded version of Lagrangian fluid finite element including the effects of compressible wave propagation and surface sloshing motion, and three-dimensional version of Drucker–Prager model based on associated flow rule assumption were programmed in FORTRAN language by authors and incorporated into the program NONSAP. Two new components added into the NONSAP were tested on a simple fluid tank and a simple fluid–structure system and obtained very reasonable results.     

Solving linear systems on a vector computer

This paper gives a classification for the triangular factorization of square matrices. These factorizations are used for solving linear systems. Efficient algorithms for vector computers are presented on basis of criteria for optimal algorithms. Moreover, the Gauss—Jordan elimination algorithm in a version which admits efficient implementation on a vector computer is described. Comparative experiments in FORTRAN 77 with FORTRAN 200 extensions for the Cyber 205 are reported.     

Computer program for the discrete linear restricted Chebyshev approximation

This paper constitutes a computer program for the discrete linear restricted Chebyshev approximation problem. The program is written in ANSI basic FORTRAN language. The ordinary Chebyshev solution, the one-sided Chebyshev solutions and the Chebyshev approximation by non-negative functions may be calculated as special cases by this program.     

Notice

In a recent issue of this journal, Trypia presented a simple rule to determine the blending pattern and quantities for a multi‐product blending firm. This paper presents three variations of Trypia's model suitable for discussion in production management and mathematical modelling courses. First, it presents a generalized version of Trypia's problem leading to a linear programming formulation. Next a more realistic version of Trypia's problem including set‐up costs is presented together with a simple method for determining production sequence and quantities. Finally, the case of sequence dependent set‐up costs is discussed.     

Implementation of EOQ and Lambert W function in 1-D engine simulation model for optimizing fuel injection in GDI engine

The aim of this study was to implement Economic Order Quantity method (EOQ) together with the Lambert W function in a 1-D engine simulation model in order to develop a fuel control strategy for a Gasoline direct injection (GDI) engine. Previous work of the co-author demonstrated the possibility of optimizing fuel injection quantity in GDI engine using the EOQ that is commonly used in supply chain of perishable products. This work extends the previous work and implements it in a 1-D, crank angle resolved, engine simulation model for the application of model based calibration process. The present work uses a validated engine simulation model, which is based on predictive combustion modelling approach, and couples the 1-D engine simulation model with SIMULINK to add the evaporation, wall- wetting and heat transfer models. It employs FORTRAN subroutines to modify the internal code of the 1-D simulation software in order to add crank angle resolved evaporation model. Finally, EOQ with Lambert W function was added to the model using MATLAB with special attention to the decimal control for the solution. This study demonstrated that EOQ and Lambert W functions together are a suitable method to develop fuel control strategy for a model based calibration procedure when implemented in crank angle resolved 1-D simulation model.     

Derivation of near-optimal pump schedules for water distribution by simulated annealing

The scheduling of pumps for clean water distribution is a partially discrete non-linear problem with many variables. The scheduling method described in this paper typically produces costs within 1% of a linear program-based solution, and can incorporate realistic non-linear costs that may be hard to incorporate in linear programming formulations. These costs include pump switching and maximum demand charges. A simplified model is derived from a standard hydraulic simulator. An initial schedule is produced by a descent method. Two-stage simulated annealing then produces solutions in a few minutes. Iterative recalibration ensures that the solution agrees closely with the results from a full hydraulic simulation.     

Confidence regional method of stochastic spanning tree problem

We consider a P model version of stochastic spanning tree problems with random edge costs. Parameters of underling probability distribution of edge costs are unknown and so they are estimated by a confidence region from statistical data. The problem is first transformed into a deterministic equivalent problem with a minimax type objective function and a confidence region of means and variances, since we assume normal distributions with respect to random edge costs. Our model reflects the situation that the maximum possible damage due to an unknown parameter should be minimized. We show the problem can be reduced to the deterministic equivalent problem of another stochastic spanning tree problem, which is already investigated by us. Thus, we can find an optimal spanning tree of the original problem very efficiently by this reduction.     

Cost allocation games with information costs

We propose a simple model which embeds cost allocation games into a richer structure to take into account that information on costs can be itself costly. The model is an outgrowth of experience on cost allocation for consortia of municipalities dealing with garbage collection.The authors thank an anonymous referee for having pointed out a mistake in the previous version of Lemma 1     

Combined Cost and Linear Programming Models of Industrial Complexes

Many industrial complexes are chains of unit processes, the end-product of one process being the raw material for another; often the same process can also make several end-products sequentially and, furthermore, intermediate products can be bought in or sold. In managing these "multi-processes", cost accountants often use input/output models to measure historic internal costs while simultaneously, planners calculate the most profitable future mix of end-products from linear programming (LP) models. A general combined cost/LP model is proposed here, usable either for costing purposes or for LP planning. Its cost version can include standard cost techniques; when used with the planning version, it leads to the concept of "super-standard" costs for the most profitable way of running the multiprocess. The combined model is thus a basic part of an overall management information and control system.     

The salvo combat model with a sequential exchange of fire

This paper develops a version of the stochastic salvo combat model in which the exchange of fire is sequential, rather than simultaneous. This sequential-fire version is built by modifying the equations in the original simultaneous-fire version. The performance of the sequential model is tested by comparing its outputs with those of a Monte Carlo simulation. The fit between the model and the simulation is very close, especially for the mean and standard deviation of losses. The model is then applied to the Battle of the Coral Sea. The results suggest that attacking first would have given the American force a larger advantage than that provided by an extra aircraft carrier.     

Simulation in Microcomputers Revisited

This note discusses experiences in running discrete-events simulation models on an Apple II microcomputer. The use of PASCAL as a simulation language is commented on. To give an indication of the type of simulations that can be run on a micro, a fairly complex model relating to icebreaking operations is discussed. Run times for this model are mentioned. It is indicated how those run times can be reduced by programming part of the random number generation in assembly language. The conclusion is that significant simulation work can be done on a small micro like the Apple II.     

The McCormack model for gas mixtures: The temperature-jump problem

An analytical version of the discrete-ordinates method (the ADO method) is used to establish a concise and particularly accurate solution to the temperature-jump problem for a binary gas mixture described by the McCormack kinetic model. The solution yields, in addition to the temperature-jump coefficient for the general (specular–diffuse) case of Maxwell boundary conditions for each of the two species, the density and temperature profiles for both types of particles. Numerical results are reported for two binary mixtures (Ne-Ar and He-Xe) with various molar concentrations. The algorithm is considered especially easy to use, and the developed (FORTRAN) code requires typically less than a second on a 2.2 GHz Pentium 4 machine to compute all quantities of interest.     

Nonstationary Spatial Gaussian Markov Random Fields

Thin-plate splines have been widely used as spatial smoothers. In this article, we present a Bayesian adaptive thin-plate spline (BATS) suitable for modeling nonstationary spatial data. Fully Bayesian inference can be carried out through efficient Markov chain Monte Carlo simulation. Performance is demonstrated with simulation studies and by an application to a rainfall dataset. A FORTRAN program implementing the method, a proof of the theorem, and the dataset in this article are available online.     

Simulation model of multi-compartment distribution in the catering supply chain

An efficient distribution system of high performance is needed to anticipate market developments in the catering supply chain (CSC) in the Netherlands. A simulation model was developed to analyse a multi-compartment distribution system which should satisfy customer demands for shorter lead times, increased delivery frequency and improved quality of process and product. The simulation model quantifies logistic and financial performances in various alternative logistic scenarios for multi-compartment distribution in the catering supply chain. This stochastic simulation model was constructed on the basis of a value chain analysis yielding activities and performance indicators (PIs). The model proved to be accurate in its predictions when applied to a case situation taken from the Dutch CSC. It is concluded that discrete event simulation is an effective tool to evaluate promising logistic scenarios. The new, multi-compartment method of distribution allowed for a 14% decrease in total costs in the Dutch CSC while satisfying customer demands.     

The McCormack model for gas mixtures: The temperature-jump problem

An analytical version of the discrete-ordinates method (the ADO method) is used to establish a concise and particularly accurate solution to the temperature-jump problem for a binary gas mixture described by the McCormack kinetic model. The solution yields, in addition to the temperature-jump coefficient for the general (specular–diffuse) case of Maxwell boundary conditions for each of the two species, the density and temperature profiles for both types of particles. Numerical results are reported for two binary mixtures (Ne-Ar and He-Xe) with various molar concentrations. The algorithm is considered especially easy to use, and the developed (FORTRAN) code requires typically less than a second on a 2.2 GHz Pentium 4 machine to compute all quantities of interest.Received: November 18, 2003; revised April 14, 2004     

Simulation and analysis of rotary forging a ring workpiece using finite element method

The methods of dealing with some key problems in analyzing a rotary forging process with a finite element method are given. The presented mechanical model of the finite element analysis is in accordance with the actual conditions of the rotary forging process. A three-dimensional rigid–plastic finite element analysis code is developed in FORTRAN language and used to analyze the rotary forging process of a ring workpiece. Velocity fields and stress–strain fields of both contact and non-contact zones of the ring workpiece in the rotary forging are obtained. The deformation mechanism and metal flow laws of the contact zone surface of the ring workpiece in the rotary forging process are revealed. The pressure distributions of the contact surface along the radial and tangential directions and effects of rotary forging parameters on deformation characteristics are given.     

Inventory sharing in integrated network design and inventory optimization with low-demand parts

Service Parts Logistics (SPL) problems induce strong interaction between network design and inventory stocking due to high costs and low demands of parts and response time based service requirements. These pressures motivate the inventory sharing practice among stocking facilities. We incorporate inventory sharing effects within a simplified version of the integrated SPL problem, capturing the sharing fill rates in 2-facility inventory sharing pools. The problem decides which facilities in which pools should be stocked and how the demand should be allocated to stocked facilities, given full inventory sharing between the facilities within each pool so as to minimize the total facility, inventory and transportation costs subject to a time-based service level constraint. Our analysis for the single pool problem leads us to model this otherwise non-linear integer optimization problem as a modified version of the binary knapsack problem. Our numerical results show that a greedy heuristic for a network of 100 facilities is on average within 0.12% of the optimal solution. Furthermore, we observe that a greater degree of sharing occurs when a large amount of customer demands are located in the area overlapping the time windows of both facilities in 2-facility pools.