Dmitrij Šešok

Global optimization of trusses with a modified genetic algorithm

Abstract In this paper, a technology enabling the optimization of the topology of truss or frame structures with genetic algorithms is presented. It has been shown that due to a huge number of possible variants the global solution of similar problems with exhaustive search algorithms is feasible only for systems possessing small numbers of d.o.f. s (usually until 10 nodes). These problems can be solved in a reasonable time by genetic algorithms. The modified genetic algorithm for optimization of topology of truss systems is suggested, where the repair of the genotype, instead of some constraint is used. The solution of numerical examples with original software illustrates the efficiency of proposed technology; the global solutions are obtained in all cases.

OPTIMAL PLACEMENT OF PILES IN REAL GRILLAGES: EXPERIMENTAL COMPARISON OF OPTIMIZATION ALGORITHMS

The aim of the article is to choose algorithms suited for optimal placement of piles in real grillages by performing experimental comparison of different global optimization algorithms. The comparison includes several algorithms: random search, metaheuristics (simulated annealing and genetic algorithm) and local optimization combined with random search. The algorithms are compared using the results of optimization of pile placement schemes of 10 practical grillages of small-to-medium scale with data obtained from several design bureaus. The best results have been achieved with simulated annealing and nonlinear optimization algorithm NEWUOA combined with heuristic random search. http://dx.doi.org/10.5755/j01.itc.40.2.427

Some insights on the optimal schemes of tall guyed masts

AbstractThe article presents the technique for simultaneous topology, shape and sizing optimisation of tall guyed masts under wind loadings and self-weight using simulated annealing. The objective function is the mass of the mast structure including guys, while the set of design parameters may consist of up to 10 parameters of different nature. The constraints are assessed according to Eurocodes and include the local and global stability constraints, limitations on the slenderness in mast elements, and strength constraints. The proposed optimisation technique covers three independent parts: the optimisation algorithm, meshing pre-processor that yields computational scheme of mast depending on the design parameters, and finite element program evaluating the objective function and constraints via penalisation technique. As an example the results of optimisation of a typical 60 m tall guyed telecommunication mast with different antenna areas are presented. On the basis of these results, the authors try ascer...

Packing of Polydispersed Discs into Containers of Regular Shape

A geometric algorithm for the packing of a given sequence of polydispersed circular particles into containers of regular polygon shape is suggested. The proposed algorithm aims for a twofold goal: obtaining the maximum packing density and following the prescribed homogeneity distribution laws of polydispersed particles. When seeking for maximum density, the obtained packing is further optimized by several heuristic and stochastic optimization algorithms. The objective function for the optimization algorithm is supplied by the “black-box” routine, which can either determine the best possible place in the packing for each particle or allow arbitrary narrowing of the placement domain, thus accelerating the computations. The quality of packing rendered by the packing routine depends only on the initial sequence of the particles in a set. The obtained packing is stable with respect to gravitational effects. The performance of optimization methods was studied using benchmark tests of periodic and non-periodic packing of mono- and poly-sized assemblies of circular particles. Simulation quality is controlled by packing density and computational efficiency. The stability of the generated packing is proved using a discrete element method.

On Bayesian Approach to Grillage Optimization

In this paper, a new simplified version of the Bayesian Approach to coordinate global optimization (BAcoor) is compared with the well-known algorithms. BAcoor is some method of multi-dimensional optimization by applying a sequence of one-dimensional global optimizers starting from the best points obtained by previous one-dimensional optimization. The globality of one-dimension search is controlled by the only parameter e. The new element is that observation points are defined by explicit formulas. In other similar methods, such as [8, 15, 16, 10, 11], this is performed by some numerical techniques that minimize the risk functions. The efficiency of suggested method is investigated and compared with other methods by solving a real-life civil engineering global optimization problem of pile placement schemes in grillage-type foundations. This problem is a good benchmark, because the minimal value of the objective function is known so the optimization error can be defined exactly. DOI: http://dx.doi.org/10.5755/j01.itc.41.4.1670

Genetinio Algoritmo Taikymas Žemės Sklypų Ribų Topologijai Optimizuoti Nekilnojamojo Turto Kadastro Žemėlapyje

Santrauka Žymint žemės sklypų ribas nekilnojamojo turto kadastro žemėlapyje pasitaiko nesutapimų tarp gretimų sklypų ribų, t. y. atsiranda tarpai arba susidaro sanklotos. Tais atvejais, kai žemės sklypų posūkio taskų koordinatės atitinka teisės aktais nustatytus leistinumus, derinama žemės sklypų ribų topologija. Straipsnyje nagrinėjami klausimai, susije su genetinių algoritmų taikymu žemės sklypų ribų topologijai optimizuoti. Atliktas genetinio algoritmo taikymo tam tikslui metodologinis pagrindimas ir eksperimentinis tyrimas.

LYGIAGRETŪS SKAIČIAVIMAI SU CUDA

The principles of computing with NVIDIA’s parallel computing platform CUDA are analysed in the paper. Two numerical experiments, array addition and matrix multiplication and optimizing matrix multiplication (shared memory, bank conflict solutions, instruction-level parallelism) with Geforce and Quadro graphics cards and the CPU were run. Time values for computing int, float, double data types are provided in the paper.

ILGOSIOS ARITMETIKOS ALGORITMŲ GREITAVEIKOS TYRIMAS

Arbitrary-precision arithmetic libraries are analysed and computing experiments were examined in this article. During the experiments, the efficiency of different arbitrary-precision arithmetic libraries (GMP, NTL, FLINT, CLN, Java BigInteger) solving computing tasks which involve the operations of modular multiplication, division and exponentiation were examined.

Private Cloud Infrastructure for Applications of Mechanical and Medical Engineering

The paper presents the development of the private cloud infrastructure providing advanced services for research in mechanical and medical engineering. The cloud services have been developed by using Apache jclouds API and JetS3t Toolkit to enhance management of Eucalyptus cloud infrastructure and to increase accessibility of engineering software. The performance of the developed cloud infrastructure has been assessed testing CPU, memory IO, disk IO, network and the deployed software services. The obtained results have been compared with the performance of the native hardware. The technical implementation of deployed cloud services has been evaluated by the utilising a number of use cases from different research areas of mechanical and medical engineering. DOI: http://dx.doi.org/10.5755/j01.itc.44.3.7379