Wyniki wyszukiwania - BazTech

1

Application of grammatical evolution to stock price prediction

Kita E., Sugiura H., Zuo Y., Mizuno T.

Computer Assisted Methods in Engineering and Science

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2017

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Vol. 24, no. 1

67--81

EN

Grammatical evolution (GE) is one of evolutionary computation techniques. The aim of GE is to find the function or the executable program or program fragment that will find the optimal solution for the design objective such as the function for representing the set of given data, the robot control algorithm and so on. Candidate solutions are described in bit string. The mapping process from the genotype (bitstring) to the phenotype (function or program or program fragment) is defined according to the list of production rules of terminal and non-terminal symbols. Candidate solutions are evolved according to the search algorithm based on genetic algorithm (GA). There are three main issues in GE: genotype definition, production rules, and search algorithm. Grammatical evolution with multiple chromosomes (GEMC) is one of the improved algorithms of GE. In GEMC, the convergence property of GE is improved by modifying the genotype definition. The aim of this study is to improve convergence property by changing the search algorithm based on GA with the search algorithm based on stochastic schemata exploiter (SSE) in GE and GEMC. SSE is designed to find the optimal solution of the function, which is the same as GA. The convergence speed of SSE is much higher than that of GA. Moreover, the selection and crossover operators are not necessary for SSE. When GA is replaced with SSE, the improved algorithms of GE and GEM Care named “grammatical evolution by using stochastic schemata exploiter (GE-SSE)” and “grammatical evolution with multiple chromosome by using stochastic schemata exploiter (GEMC-SSE)”, respectively. In this study, GE-SSE is compared with GE in the symbolic regression problem of polynomial function. The results show that the convergence speed of GE-SSE is higher than that of original GE. Next, GE-SSE and GEMC-SSE are compared in stock price prediction problem. The results show that the convergence speed of GEMC-SSE is slightly higher than that of GE-SSE.

2

Fotowoltaika w budownictwie jako odpowiedź na światowe regulacje prawne

Kita E., Przenzak E.

Budownictwo i Prawo

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2017

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R. 20, nr 1

25--28

PL

Przywołując unijne i światowe dyrektywy i rozporządzenia, wskazano fotowoltaikę (PV) jako jeden ze sposobów pozwalających na częściowe rozwiązanie problemów obecnej energetyki. Dotyczy to głównie redukcji emisji zanieczyszczeń do atmosfery oraz zmniejszania zużycia energii ze źródeł konwencjonalnych. Zaznaczono możliwość integracji instalacji fotowoltaicznych z budynkami do celów produkcji energii elektrycznej na potrzeby użytkowników. Zwrócono uwagę zarówno na zalety, jak i wady systemów fotowoltaicznych. Ponadto, opisano poszczególne elementy konieczne do zastosowania w każdej instalacji fotowoltaicznej wyspowej oraz pracującej w trybie przyłączenia do sieci.

EN

Considering EU and world directives and regulations, photovoltaics (PV) is indicated as one of the ways that enabling to partially solve the problems of today power engineering. This applies mainly to the reduction of air pollution in the atmosphere as well as to the reduction of energy consumption from conventional sources of energy. There is a possibility of integrating photovoltaic installation with buildings used for producing electricity for normal users. There are advantages as well as disadvantages of photovoltaic systems. In addition, specific elements are described necessary to be used in every independent photovoltaic installation and in the case of installations connected to the network.

3

Traffic network design by cellular automaton-based traffic simulator

Kita E., Nanya W., Wakita Y., Tamaki T.

Computer Assisted Methods in Engineering and Science

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2015

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Vol. 22, no. 1

51--61

EN

Braess pointed out that adding a new road to overcome a traffic congestion could cause a new traffic congestion leading to the reduction of the traffic flow in the whole traffic network, which is called Braess’ paradox. The aim of this study is to formulate a traffic network design algorithm to increase the traffic flow in a traffic network. The objective function is the traffic flow of the whole traffic network and the route selection at the corners is considered as design variable. The traffic flow is estimated by a traffic flow simulator based on the cellular automaton model. A simple traffic network is considered as a numerical example. At different traffic densities, the traffic network is optimized to maximize the traffic flow. The results show that the optimized traffic network depends on traffic density. The situation presented by Braess’ paradox could disappear at high traffic density.

4

Application of grammatical evolution to coefficient identification problem in two-dimensional elastic problem

Kuroda T., Sugiura H., Kita E.

Computer Assisted Methods in Engineering and Science

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2013

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Vol. 20, no. 1

3--13

EN

Grammatical evolution (GE), which is a kind of evolutionary algorithms, is designed to find a function, an executable program or program fragment that will achieve a good fitness value for the given objective function to be minimized. In this study, GE is applied for the coefficient identification problem of the stiffness matrix in the two-dimensional elastic problem. Finite element analysis of the plate with a circular hole is performed for determining the set of the stress and the strain components. Grammatical evolution determines the coefficient matrix of the relationship between the stress and strain components. The coefficient matrix is compared with Hooke's law in order to confirm the validity of the algorithm. After that, three algorithms are shown for improving the convergence speed of the original GE algorithm.

5

Solving two-dimensional packing problem using particle swarm optimization

Shin Y.-B., Kita E.

Computer Assisted Methods in Engineering and Science

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2012

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Vol. 19, no. 3

241-255

EN

Particle swarm optimization is one of the evolutionary computations which is inspired by social behavior of bird flocking or fish schooling. This research focuses on the application of the particle swarm optimization to two-dimensional packing problem. Packing problem is a class of optimization problems which involve attempting to pack the items together inside a container, as densely as possible. In this study, when the arbitrary polygon-shaped packing region is given, the total number of items in the region is maximized. The optimization problem is defined not as the discrete-value optimization problem but as the continuous- value optimization problem. The problem is solved by two algorithms, original and improved PSOs. In the original PSO, the particle position vector is updated by the best particle position in all particles (global best particle position) and the best position in previous positions of each particle (personal best position). The improved PSO utilizes, in addition to them, the second best particle position in all particles (global second best particle position) in the stochastic way. In the numerical example, the algorithms are applied to three problems. The results show that the improved PSO can pack more items than the original PSO and therefore, number of the successful simulations is also improved.

6

Utility analysis of zipper-merging for improvement of traffic jam by CA simulation

Wakita Y., Shimizu H., Iguchi T., Kita E.

Journal of Technical Physics

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2009

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Vol. 50, no 4

387-401

EN

When slow vehicles go at the merging point of roads from a branch road to a main road, a traffic jam occurs there. Some researchers pointed out that the zipper merging of the vehicles is effective for reducing the traffic jam near the merging point of roads. The aim of this study is to discuss the effectiveness of the zipper merging by using cellular automata simulation. The vehicle behavior is modeled according to the single and multiple vehicles following models. While, in the single vehicle following model, the acceleration rate depends ou the velocity difference with the nearest vehicle ahead alone, the multiple vehicles following model controls the acceleration rate according to the velocity differences with three vehicles ahead. The results show that, in the case of the single vehicle following model, the maximum speed reduction is about 40% in case of no-zipper merging and 20% in case of zipper merging. In addition to that, the multiple vehicle following model can recover the velocity sooner than the single vehicle following model. Therefore, we can conclude that the combinational use of the zipper merging and the multiple vehicles following model can reduce successfully the traffic jam near the merging point of roads.

7

Improvement of evolutionary algorithm based on schema exploiter

Maruyama T., Kita E.

Computer Assisted Mechanics and Engineering Sciences

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2008

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Vol. 15, No. 2

85-98

EN

Stochastic Schemata Exploiter (SSE) is one of the evolutionary optimization algorithms for solving the combinatorial optimization problems. We present the Extended SSE (ESSE) algorithm which is composed of the original SSE and new ESSE operations. The ESSE is compared with the original SSE, simple genetic algorithm (SGA), and GA with Minimal Generation Gap (MGG) in some test problems in order to discuss its features.

8

Application of Trefftz method for temperature rise analysis on human skin exposed to radiation

Kita E., Hirayama Y.

Computer Assisted Mechanics and Engineering Sciences

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2008

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Vol. 15, No. 1

45-52

EN

This paper describes the application of the Trefftz method to the temperature rise in human skin exposed to radiation from a cellular phone. A governing equation is given as the Poisson equation. An inhomogeneous term of the equation is approximated with a polynomial function in Cartesian coordinates. The use of the approximated term transforms the original boundary-value problem to that governed with a homogeneous differential equation. The transformed problem can be solved by the traditional Trefftz formulation. Firstly, the present method is applied to a simple numerical example in order to confirm the formulation. The temperature rise in a skin exposed to radiation is considered as a second example.

9

Simulation of traffic flow through a toll gate

Shimizu H., Hara A., Tamaki T., Kita E.

Computer Assisted Mechanics and Engineering Sciences

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2007

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Vol. 14, No. 1

91-106

EN

This paper describes the simulation of the traffic flow through toll gate. A two-lane road is considered as the object domain and then, the local rules are defined to control the vehicle behavior. First, one simulates the traffic flows through the road with two non-ETC gates or the road with two ETC gates. The maximum traffic amount on the roads with two ETC gates is less than that on the road without gates by about 10%, while, in the case of the roads with two non-ETC gates, the maximum traffic amount decreases by 80%. Next, one simulates the traffic flows through the road with one non-ETC gate and one ETC gate. The traffic amount depends not only on the vehicle occupancy but also on the percentage of ETC vehicles among all driving vehicles.

10

Topology and shape optimization of continuum structures by genetic algorithm and BEM

Kita E., Tamaki T., Tanie H.

Computer Assisted Mechanics and Engineering Sciences

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2004

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Vol. 11, No. 1

63-75

EN

This paper describes the topology and shape optimization scheme of continuum structures by using genetic algorithm (GA) and boundary element method (BEM). The structure profiles are defined by using the spline function surfaces. Then, the genetic algorithm is applied for determining the structure profile satisfying the design objectives and the constraint conditions. The present scheme is applied to minimum weight design of two-dimensional elastic problems in order to confirm the validity.

11

Application of cellular automata simulation to truss structure design

Kita E., Toyoda T., Tamaki T., Xie Y. M.

Computer Assisted Mechanics and Engineering Sciences

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2004

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Vol. 11, No. 4

321-335

EN

In the cellular automata simulation, the object under consideration is divided into small cells and the simulation is performed according to the local rule which is defined as the local relationship among cells. In this paper, the concept of cellular automata is applied to the design scheme of truss structures. First, truss elements are considered as the cells of the cellular automata and the local rule is derived from the optimization problem. The objective functions are defined to minimize the total weight of the structure and to obtain even stress distribution in the whole structure. The constraint conditions are introduced in order to define the local rule. The present method is applied to the design of the plane and the three-dimensional truss structures such as Schwedler and Lamella Domes. The convergence histories of the total weight and the mean and the maximum stresses are shown in order to discuss the property of the present method.

12

Oxidation of 3-Hydroxy-6-methyl-2-pyridinemethanol by Chromium(VI) in Acidic Aqueous Media ; Kinetic and EPR Studies

Kita E., Wrzeszcz G.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 3

355-364

EN

Kinetics of oxidation of 3-hydroxy-6-methyl-2-pyridinemethanol (hmpol) by CrVI at HClO4 was studied under the pseudo-first-order conditions. The hmpol oxidation products were the appropriate aldehyde (hmpal) and acid (hmpac) coordinated to the chromium( III). The linear dependence of the pseudo-first-order rate constant (kobs) on [hmpol] at 1.0 and 2.0 M HClO4 and a parabolic dependence of kobs on [H+] were established. The apparent activation parameters were determined from the second-order rate constants at 1.0MHClO4. The presence of the CrII and CrIV intermediates was deduced, based on rate retardation effect caused by O2 and MnII respectively, whereas the presence of CrV was established by EPR. Some correlations between the structure and stability of intermediate chromium(V) complexes have been discussed from EPR spectra, recorded during the redox process.

13

Application of Trefftz method to steady-state heat conduction problem in functionally gradient materials

Kita E., Ikeda Y., Kamiya N.

Computer Assisted Mechanics and Engineering Sciences

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2003

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Vol. 10, No. 3

339-351

EN

This paper describes the application of Trefftz method to the steady-state heat conduction problem on the functionally gradient materials. Since the governing equation is expressed as the non-linear Poisson equation, it is difficult to apply the ordinary Trefftz method to this problem. For overcoming this difficulty, we will present the combination scheme of the Trefftz method with the computing point analysis method. The inhomogeneous term of the Poisson equation is approximated by the polynomial of the Cartesian coordinates to determine the particular solution related to the inhomogeneous term. The solution of the problem is approximated with the linear combination of the particular solution and the T-complete functions of the Laplace equation. The unknown parameters are determined so that the approximate solution will satisfy the boundary conditions by means of the collocation method. Finally, the scheme is applied to some numerical examples.

14

Structural optimization method based on cellular automata simulation

Toyoda T., Kita E.

Computer Assisted Mechanics and Engineering Sciences

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2002

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Vol. 9, No. 2

191-203

EN

This paper describes the topology and the shape optimization scheme of the continuum structures using the cellular automata simulation. The design domain is divided into small square cells. By considering the cells as the elements, the stress analysis of the structure is carried out by finite element method. Then, the design variables are updated according to the local rule and the stress distribution. The rule is defined as the simple relationship between a cell whose design variable is updated and its neighborhood cells. In this paper, we will discuss the formulation to analytically derive the rules from the optimization problems. The special constraint condition named as ``CA-constraint condition'' is introduced first and then, the global optimization problem for the whole structure is divided into the local problem for some neighboring cells. The derived rules are applied to the same numerical example in order to discuss the theoretical validity of the formulation and the feature of the rules.

15

Studies on mechanism of 2-pyridinecarboxaldehyde oxidation by dichromates in strongly acidic aqueous solutions. The unusual reaction order on concentration of the aldehyde

Kita E., Kita P., Uścińska G.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 8

1949-1957

EN

2-Pyridinecarboxaldehyde (pyad) has been oxidized by Cr2O7(-2) ion at pH range 0-1 to 2-pyridinecarboxylic acid (pyac). The produced CR(III) exists in the form of three complex ions: [CR(pyac)(H2O)4](2+), [Cr(pyac)2(H2O)2](+) and [Cr(H2O)6](3+). The reaction follows unusual mixed fourth-order rate law: first-order on concentrations of H(+)-aq and CR(VI) and second-order on concentration of the aldehyde. Mechanism of the reaction has been discussed.

16

Studies on kinetics and mechanism of oxidation of pyridoxal by dichromates in aqueous HClO4 solutions

Kita E., Kita P., Pietkiewicz A., Wrzeszcz G., Rozpłoch F.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 3

573-581

EN

Oxidation of pyridoxal (PL) by Cr2O7(2-) ion has been studied using an excess of the aldehyde under air or argon atmospheres. The reaction leads mainly to two Cr(III) complexes: [Cr(PA)(H2O)4](2+) and [Cr(H2O)6](3+) and to uncoordinated pyridoxic acid (PA). The rate of PL oxidation follows a mixed third order rate law: first order in concentrations of Cr(VI), Pl and H3O(+). The reduction of Cr(VI) toCr(III) proceeds through chromium(V) intermediate complex, which has been detected by the EPR method. Mechanism of the reaction has been discussed.

17

2D shape optimization using genetic algorithm

Kita E., Tanie H.

Computer Assisted Mechanics and Engineering Sciences

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1998

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Vol. 5, nr 3

311-321

EN

This paper presents an optimal design method of continuum structures by genetic algorithm. Profiles of the objects under consideration are represented by the spline functions and then, the chromasomes for the profiles are defined by the coordinates of the control points of the functions and the material code of the structures. The profiles and the material code are optimized by the genetic operations in order to determine the object satisfying the design objectives. The minimum weight design of the plate is considered as a typical example. The present method is applied to the problem in which the profile and the material of the objects are unknown.