Wyniki wyszukiwania - Biblioteka Nauki

1

Optimization of variable thickness plates by genetic algorithms

100%

Pyrz M.

Engineering Transactions

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1998

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tom Vol. 46, iss. 1

115-129

EN

The implementation of genetic algorithms to the optimal design of variable thickness plates is presented. Thin, elastic, piecewise constant thickness plates subjected to bending are investigated. The material distribution that minimizes the structural strain energy under constant volume constraint is searched. In numerical examples, square plates loaded by uniform normal pressure are optimized for different boundary conditions. The best designs are compared with the worst solutions, corresponding to the maximization of the strain energy. Significant changes in strain energy can be achieved by modyfying thickness distribution for the same material volume. The performances of the approach are discussed.

2

Transfer kadmu, olowiu, cynku, miedzi i magnezu z organizmu matki do organizmu potomstwa poprzez zdrowy i chorobowo zmieniony gruczol mlekowy owiec

100%

Pyrz M.

Rozprawy Naukowe. Akademia Rolnicza w Lublinie

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2006

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nr 306

1-88

3

Application of Evolutionary Algorithms to the Identification of Parameters of New Smart Structures : Preliminary Approach

63%

Pyrz M. , Zalewski R.

Machine Dynamics Problems

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2006

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tom Vol. 30, No. 2

136-145

EN

A new "smart structure", based on granular materials encapsulated in an elastic envelope, is proposed and investigated in the paper. Fundamental mechanical properties of the specially prepared granular testing specimens are described by the viscoplastic constitutive Chaboche's model. The experimental results of uniaxial tests are presented and applied to the identification of parameters of the Chaboche's law. The proposed procedure of material parameters estimation is based on evolutionary algorithms, solving corresponding optimization problem. The efficiency of the approach and the quality of the results are discussed.

4

Modelling of the Viscoplastic Behaviour of Homogeneous Solid Propellants

63%

Pyrz M. , Zalewski R.

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2015

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tom Vol. 12, no. 1

159--174

EN

This study is concerned with the mechanical properties of homogenous solid propellants. The experimental results demonstrate the high strain rate sensitivity of these materials. A modified viscoplastic model of the Bodner- Partom type was applied to simulate the nonlinear behaviour of solid propellants when subjected to uni-axial loading conditions. The material parameters of the constitutive law were identified numerically using the evolutionary algorithm. The capability of the proposed approach was investigated for a representative solid fuel sample. The efficiency of the method is discussed.

5

Evolutionary programs in the optimization of cementless hip prosthesis

63%

Bauer J. , Pyrz M.

Engineering Transactions

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2001

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tom Vol.49, iss.2/3

417-429

EN

The optimal design of cementless hip prosthesis is investigated in the paper. Design variables are materials (represented by their Young's moduli) of the non-homogenous stem prosthesis, disposed in vertical layers. The minimisation of the interface stress function with constraints on the resorbed bone mass reaction is presented. A simplified two-dimensional FEM model of a stem-bone configuration is considered, enabling however to obtain essential characteristics of the stem-bone load-transfer mechanism. Evolutionary algorithm approach is applied to find the optimal solution.

6

Modeling of Solid Propellants Viscoplastic Behavior Using Evolutionary Algorithms

51%

Zalewski R. , Pyrz M. , Wolszakiewicz T.

Central European Journal of Energetic Materials

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2010

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tom Vol. 7, nr 4

289-300

EN

In the paper an initial attempt to the experimental analysis of viscous effects, characteristic for homogeneous solid rocket fuels is proposed. For this reason uniaxial tensile experiments, carried out on dumbbell homogeneous solid propellants have been chosen. Laboratory tests have been carried out on INSTRON tensile testing machine. Research schedule involved destructive tensile tests with various strain rates. Three different values of strain rates have been taken into consideration. Experimentally obtained hardening curves are presented in suitable diagrams. Basing on obtained results, authors confrm the viscoplastic behavior of studied materials. Essential impact of the applied strain rate on the position of experimental hardening curves is observed. Acquired results are the base for the further stage of investigations of homogeneous solid propellants – the modeling of their physical properties. Additionally, numerical modeling of studied phenomena, using the viscoplastic Chaboche’s model, identifed on the basis of experimental data, is presented. The material parameters of the constitutive law are determined numerically using an evolutionary algorithm procedure. The effciency of the model and the identifcation approach are discussed.

7

Levels of hematological parameters of pigs over the fattening period

51%

Chmielowiec-Korzeniowska A. , Babicz M. , Pyrz M.

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2008

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tom 26

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nr 3

19-24

8

On Updating Finite Element Models of Real Structures Using Genetic Algorithm

51%

Touat N. , Pyrz M. , Rechak S.

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tom Vol. 32, No. 2

74-87

EN

An efficient method of updating numerical models for dynamics problems is presented. The objective is to minimize the difference between measured and simulated vibration data. The corresponding optimization problem is formulated in the modal domain and solved using the genetic algorithm (GA) stochastic algorithm. Original modifications of a standard GA are proposed to improve the updating process efficacy. New versions of GA exploit the speeding up procedures developed in the novel accelerated random search (ARS) algorithm. A finite element model of a lumped mass structure is analyzed to validate the approach. A real beam-like structure model is updated, making use of experimental modal data. The enhanced GA enables us to obtain results well correlated with experiments.

9

Modeling of Solid Propellant Non-Linear Properties with Thermal Loading History

51%

Pyrz M. , Wolszakiewicz T. , Zalewski R.

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tom Vol. 32, No. 3

80-90

EN

The paper discusses experimental results obtained for a selected group of solid propellants with and without previous thermal loading history. The viscoplastic constitutive model of Chaboche is proposed to model nonlinear properties of the studied material. An effective method of model parameters identification, based on evolutionary algorithms, is applied. The results of numerical simulations are in very good agreement with experimental data.

10

Estymacja parametrów modelu tłumika magneto-reologicznego z wykorzystaniem algorytmów genetycznych

51%

Grzesikiewicz W. , Makowski M. , Pyrz M.

Pomiary Automatyka Kontrola

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2011

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tom R. 57, nr 9

1044-1047

PL

Praca jest poświęcona opracowaniu metody wyznaczania parametrów modelu tłumika magneto-reologicznego na podstawie badań eksperymentalnych. Obiektem badań był sterowany tłumik magneto-reologiczny (MR), w którym możliwe było sterowanie siłą tłumienia. Do badań numerycznych zaproponowano matematyczny model tłumika MR oraz przedstawiono przykładowe wyniki badań eksperymentalnych i symulacyjnych. Przyjęto kryterium oceny zgodności do oceny przyjętych parametrów modelu na podstawie wyników z badań eksperymentalnych i symulacyjnych. Do estymacji parametrów modelu tłumika MR użyto metody optymalizacyjne, gdzie najlepszą zgodność uzyskano przy metodzie algorytmów genetycznych.

EN

A control algorithm for a damping system equipped with the magneto-rheological damper (MR) is presented in this paper. The magneto-rheological damper (MR) enabling the control of a damping force in time was used as a test object. The paper presents the MR damper mathematical model and some examples of experimental and simulation results. The experimental studies were carried out with use of a hydraulic pulsator and a mechanical system equipped with the examined MR damper. There is described the method for selecting model parameters of the MR damper. To improve simulation and experimental results there was implemented the minimization criterion. The paper discusses several methods of optimized selection of the MR damper parameters. The best results were obtained using the methods based on genetic algorithms. Numerical investigations were performed in Matlab / Simulink with Optimtool Matlab library. Knowledge of the properties of a damper - energy dissipater - and its dissipation characteristics creates the possibility of finding its new applications to vibration control in suspension and transmission system of building structures, machines and machinery.

11

Modelowe badania prototypu tłumika magnetoreologicznego

51%

Bajkowski J. , Pyrz M. , Zalewski R.

Modelowanie Inżynierskie

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2010

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tom T. 9, nr 40

7-14

PL

W pracy przedstawiono wyniki badań eksperymentalnych prototypu tłumika magnetoreologicznego, przeznaczonego do wykorzystania w kontrolowanym procesie tłumienia drgań mechanicznych wybranej grupy urządzeń. Główną uwagę skupiono na przedstawieniu zastosowanego rozwiązania konstrukcyjnego oraz na analizie odpowiedzi badanego urządzenia na zadany eksperymentalnie rodzaj wymuszenia kinematycznego. Zgromadzona baza doświadczalna posłużyła, w dalszym etapie, jako punkt wyjściowy do ustalenia reprezentatywnego modelu reologicznego dla rozpatrywanego tłumika. Do analiz numerycznych wybrano model Bouc-Wena. Przeprowadzono estymację parametrów materiałowych modelu, wykorzystując algorytm symulowanego wyżarzania. W końcowej części pracy dokonano weryfikacji dokładności modelu numerycznego poprzez porównanie jego odpowiedzi z rezultatami eksperymentalnymi.

EN

The experimental results of the magnetorheological damper prototype, designed for controlled damping of mechanical vibrations are presented in this work. Main attention is devoted to the description of the considered construction and to the investigation of the damper's response to kinematical excitation applied experimentally. The acquired data was the initial point for the choice of a suitable rheological model for the device under consideration. The Bouc-Wen model has been selected for numerical analysis. The estimation of model parameters was made using the simulated annealing algorithm. At the final part of the paper the exactitude of the numerical model has been verified by comparing it with experimental results.

12

Bactericidal, fungicidal and virucidal properties of nanosilver. Mode of action and potential application. A review

45%

Chmielowiec-Korzeniowska A. , Krzosek L. , Tymczyna L. , Pyrz M. , Drabik A.

Annales Universitatis Mariae Curie-Skłodowska. Sectio EE: Zootechnica

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2013

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tom 31

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nr 2

13

Assessment of nanosilver particles fungicidal activity toward Candida spp. isolated from the feet of adult human carriers

38%

Chmielowiec-Korzeniowska A. , Dobrowolska M. , Tymczyna L. , Banach M. , Wlazlo L. , Trawinska B. , Pyrz M.

Annales Universitatis Mariae Curie-Skłodowska. Sectio EE: Zootechnica

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2016

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tom 34

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nr 4

14

Effect of pig farm on microbial contamination of soil

38%

Trawinska B. , Jozwik M. , Nowakowicz-Debek B. , Chmielowiec-Korzeniowska A. , Lechowski J. , Tymczyna L. , Pyrz M.

Annals of Animal Science

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2015

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tom 15

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nr 1

15

Bakteryjne zanieczyszczenie gleby i obornika w fermie bydła w zależności od terminu badań i miejsc pobierania próbek

38%

Trawinska B. , Nowakowicz-Debek B. , Chmielowiec-Korzeniowska A. , Tymczyna L. , Pyrz M. , Lechowski J.

Medycyna Weterynaryjna

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2016

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tom 72

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nr 12

EN

The aim of bacteriological examinations was to evaluate soil and manure taken from dairy farms at different times and sampling sites. The study was conducted from September to October. Soil samples were collected directly at the wall of the barn (GI) and at distances of 15 m (GII) and 45 m (GIII) from the livestock facilities. Manure was collected inside the building, at the entrance (KI) and at 1/4 (KII) and ½ (KIII) of its length. Air temperature, relative humidity and the moisture content of the samples were recorded at the sampling sites. The soil and manure samples were subjected to quantitative and qualitative bacteriological examinations conducted in accordance with Polish Standards. Statistical analysis of the results was performed by a one-way analysis of variance and Duncan’s multiple comparison test. The highest number of bacteria in the soil was found at the wall of the barn. Most mesophilic bacteria, actinomycetes, coliforms and E. coli were found in late April and early May, most psychrophilic microorganisms in June, and most proteolytic bacteria at the end of December and in early January. The microbiological contamination of the soil was low (coli titer ≤ 0.01), amounting to 0.001, and it was detected only at the wall of the barn. The qualitative study of soil revealed only E. coli bacteria. The highest number of microbes in manure was found in samples from the middle of the barn (KIII) taken at the end of April and at the beginning May. Out of the bacteria examined in this study, E. coli and Enterobacter spp. were found in manure samples throughout the study period. While analyzing the impact of selected parameters, such as microclimate and humidity, on manure samples tested for bacteria, a correlation was observed between the presence of all microbes and sample moisture. The bacterial contamination of soil and manure was the biggest during the spring period, which was probably due to climatic and microclimatic conditions. However, the contamination was negligible owing to the absence of pathogenic bacteria and a high soil index. This proved that proper zoohygienic conditions were maintained on the farm.

16

Changes in hematological and immunological indices in piglets transferred from the rearing unit to the fattening unit

38%

Chmielowiec-Korzeniowska A. , Tymczyna L. , Trawinska B. , Babicz M. , Pyrz M. , Rozanski P. , Pastwa M.

Medycyna Weterynaryjna

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2015

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tom 71

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nr 07

EN

The aim of the present study was to determine the levels of selected hematological and immune indices in growers transported from the rearing unit to the fattening facility. Blood samples were analyzed for the white blood cell count and the leucogram profile. IgA, IgM, and IgG immunoglobulin contents as well as lysozyme concentration were determined in serum. The hematological evaluation indicated a significant impact of the transfer to the fattening unit on the WBC picture. In fatteners aged 11 weeks, an elevated level of neutrophils with a concomitant decline in lymphocyte numbers was observed. A higher concentration of dust as well as chemical and microbial contaminants determined in the air of the fattening unit also affected immunoglobulin concentration and lysozyme content.

17

Dezodoryzacja powietrza w oczyszczalni ścieków za pomocą otwartego biofiltra

32%

Chmielowiec-Korzeniowska A. , Tymczyna L. , Bartecki P. , Dobrowolska M. , Banach M. , Drabik A. , Pyrz M. , Pulit J.

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2015

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tom T. 94, nr 6

977-981

PL

Zawierające związki siarki powietrze z oczyszczalni ścieków zwilżano do wilgotności 95% w temp. od -2°C do 27°C i filtrowano przez zrębki dębowe, biomasę i pokruszoną korę o temp. 10–21°C. Sprawność dezodoryzacji powietrza wzrastała wraz ze wzrostem temperatury powietrza wlotowego i złoża. Odczyn i wilgotność materiału biofiltracyjnego nie wpływały na skuteczność dezodoryzacji powietrza.

EN

S compds.-contg. air from a wastewater treatment plant was wetted to the humidity of 95% at -2°C to 27°C and filtered through oak chip, biomass and bark beds at 10–21°C. The efficiency of the air deodorization increased with the increasing the inlet air and biofilter temps. Neither pH nor moisture content in the biofilter material showed any effect on the air deodorization efficiency.