Wyniki wyszukiwania - Biblioteka Nauki

1

Przykład zastosowania analizy wrazliwości w optymalizacji zbioru cech sygnałów

100%

Sławik D.

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tom R. 51, nr 9 bis

29--31

PL

Analiza wrażliwości znajduje zastosowanie w wyborze cech sygnałów zawierających najwięcej istotnych informacji o stanie lub klasie stanu badanego obiektu. Wybierane za jej pomocą cechy mogą służyć do budowy prostszych, sprawniejszych i wydajniejszych systemów diagnostycznych. W ramach badań określono jakość budowanego, na podstawie wybranych cech, modelu diagnostycznego. Zrobiono to dla przypadku, gdy cechy sygnału wybierano w sposób, który mógł wydawać się najbardziej poprawny oraz dla przypadku, gdy w wyborze cech posłużono się analizą wrażliwości. W obu przypadkach do określenia zbioru uczącego i testowego zastosowano metodę leave one aut oraz uwzględniono przypadek, w których zbiór danych testujących był równy zbiorowi danych uczących.

EN

Sensitivity analysis finds practical application in selection of signal features, which contains the most important information about state orstate class of researched object. Selected signal features may be used to design and perform simpler and more efficient diagnostic systems. Quality of built diagnostic model was determined based on chosen features. It was made in the case of signal features choice that seems to be the most correct, and in the case of features choice with application of sensitivity analysis. The "leave one out" method and method in which test set was equal to train set where applied in the both cases.

2

Optymalizacja zbioru cech sygnałów diagnostycznych maszyny wirnikowej

100%

Sławik D.

Diagnostyka

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2005

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tom Vol. 33

163--167

PL

W referacie opisano wyniki testów modeli diagnostycznych zidentyfikowanych na podstawie wartości cech sygnałów oraz informacji o stanie obiektu. Rozpatrzono dwa przypadki. W pierwszym do celów optymalizacji zbioru cech skorzystano z miar wrażliwości. W drugim przypadku uwzględniano wszystkie cechy sygnałów. Prowadząc badania, do określenia zbioru uczącego oraz testującego, skorzystano z metody leave one out. Zaproponowana w referacie metoda optymalizacji zbioru cech sygnałów znajduje zastosowanie w wyborze cech sygnałów zawierających najwięcej istotnych informacji o stanie lub klasie stanu badanego obiektu. Wybierane za jej pomocą cechy mogą służyć do budowy prostszych, sprawniejszych i wydajniejszych systemów diagnostycznych.

EN

The results of tests of diagnostics models are described in the paper. Those models are identified based on value signal feature and information of object state. Two cases were considered. The measures of sensitivities to optimization of signal features were used in the first case and all the signals features were considered in the second one. The 'leave one out' method was applied to the both cases. Sensitivity analysis can be used in selection of signal features. Such the signal features contain the most important information about state or state class of researched object. Selected signal features may be used to design and perform simpler and more efficient diagnostic systems.

3

Simplified and advanced models of a valve system used in shock absorbers

51%

Czop P. , Sławik D. , Śliwa P. , Wszołek G.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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tom Vol. 33, nr 2

173-180

EN

Purpose: The aim of this paper is to develop a model of a valve system applicable for strain and stress prediction. Design/methodology/approach: The analytical and numerical approaches are presented to provide an overview for available methods and prediction accuracy. Findings: An equivalent numerical model of a disc valve system of different complexity was developed and discussed. Research limitations/implications: It is important to provide a model functionality allowing for calculation of disc stacks supported by a coil spring and stack settings having the opening limiter. Disc stack stress and opening characteristics vs. applied pressure may be determined with simplified analytically derived model and full 2D model including almost all significant forces and moments in a stack of circular plates. An advantage of a simplified disc stack model is possibility of its implementation in an environment supporting matrix operations, e.g. Matlab. Practical implications: A valve system has to withstand the cyclic pressure load across the piston. The number of discs, their diameters and thicknesses directly affect durability of a valve system. Damper force and valve durability expressed in life-cycles are the optimization criteria considering during selection and tuning of a valve system. Originality/value: A new valve system was developed in two versions, i.e. simplified and advanced. The model allows durability prediction at the design stage reducing the testing costs of low-performance valve systems.

4

Design and development of seal components fatigue tester

51%

Czop P. , Sławik D. , Wszołek G. , Związek M.

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tom Vol. 30, nr 1

67-74

EN

Purpose: The aim of the paper is research and development concerning a fatigue tester of shock absorber seal systems. Design/methodology/approach: Analytical approach has been applied to get an understanding of a heat exchange process. The mathematical model has been formulated and validated based on the available measurements. Numerical simulation has been carried out to illustrate a heat exchange process performance. Findings: It is possible to control a seal temperature and mechanical friction related to the rod movement into the seal at the specified velocity. The model accuracy is sufficient to perform sensitivity analysis and optimize the design. Research limitations/implications: The components of a fatigue tester have to withstand the significant temperature differences in the range ~30;+140*C, e. g. hydraulic hoses, fittings, and pumps. Practical implications: We combine the analytical and experimental approach to provide customized and reliable engineering solution in the area of damper component seal development. A typical seal has a lip-like design protecting the moving parts against the leakage. It can be tested in a shock absorber or externally with use of a customized test rigs. Seal tests inside a shock absorber have numerous disadvantages. A shock absorber temperature rises during longer tests and cooling phase is required. This dramatically increases tests duration performed with the use of an expensive general-purpose hydraulic testing machinery. A compressed air or water jacket is used to accelerate the cooling process. Nevertheless, there are limitations related to the physics behind the cooling process. A seal component fatigue tester allows to perform the seal component tests out of the shock absorber. Originality/value: A new testing method provides possibility to quantify the main contributors of seal usage.

5

Application of off-line error correction method software to reproduce random signals on servo-hydraulic testers

51%

Braska D. , Czop P. , Sławik D. , Wszołek G.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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tom Vol. 40, nr 1

41-49

EN

Purpose: This paper presents an approach towards improving the test rig performance for road signals used in automotive shock absorber tests. The goal is to develop a method for correction of the test signal profile in the off-line mode. The method is intended to be implemented as a software solution without any changes either in hardware or the settings of the servo-hydraulic tester. Design/methodology/approach: A two-stage validation of the proposed correction method was conducted using a servo-hydraulic test rig and its first-principles model. The model is capable of capturing key dynamical properties over a wide operating range while being only moderately complex. Both simulation and experimental performance results are presented and discussed. Findings: The proposed method, both in the frequency and time domain, improves the tracking of the test signal by 10-20% and allows an accuracy of more than 90% to be gained using the best fit measure in the case of reproduction of white noise signals. Research limitations/implications: It is possible to consider more advanced model-based methods for performing off-line error correction. These methods can be used if an accuracy close to 100% is expected. Practical implications: The result of the investigations is the algorithm implemented in the LabView software to automatically perform the correction of the test signal before the test. Originality/value: The paper proposes a modern approach towards the validation process by applying a simulation environment. This ensures the involvement of arbitrary disturbance models to investigate key parameters of the correction method without expensive and time-consuming experimental validation. The developed model can be extended to a model of a shock absorber to simulate full interaction between the servo-hydraulic test rig and the tested product.

6

Fluid-structure simulation of a valve system used in hydraulic dampers

45%

Czop P. , Gąsiorek D. , Gniłka J. , Sławik D. , Wszołek G.

Modelowanie Inżynierskie

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2012

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tom T. 14, nr 45

197--205

EN

The aim of this paper is to develop a method for optimizing the design of a disc spring valve system by reducing the aeration and cavitation effect which negatively influences the performance of a shock absorber. A fluid structure interaction (FSI) model is used in order to modify the geometry of the valve interior and, in turn, to achieve better performance of a shock absorber. The paper analyzes the pressure distribution along theflow paths inside the valve cavity to reduce the risk of aeration and cavitation, while other important engineering aspects are omitted, e.g. durability of disc-spring valve systems as discussed in [1]. A key measure of valve improvement was chosen as deterioration of the damping force level generated by a shock absorber vs. the number of cycles during continuous cycling of the damper . The objectives of this work are as follows: (i) to present a process for reducing the complexity of the geometry of a disc spring valve system in order to perform a combined fluid-structure simulation, (ii) to show keysteps of the simulation process focusing on interactions between fluid and structure domain and to review relevant simulation results, (iii) to describe practical aspects of the simulation process, including basic parameters and boundary conditions related to the applied commercial software, (iv) to make an optimization case study to show the application scope for the simulation methodology proposed in the paper, and to confront the simulation results with experimental investigations.