Wyniki wyszukiwania - BazTech

1

Intermittent fault’s parameter framework and stochastic petri net based formalization model

Shen Q., Qiu J., Liu G., Lv K.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 2

210--217

EN

The intermittent fault widely exists in many products and brings high safety risk and maintenance cost. At present there are some different opinions on the notion of intermittent fault and there is no comprehensive parameter framework for fully describing intermittent fault. Also the formalization model which can mathematically describe intermittent fault hasn’t been constructed. In this paper, the conception of intermittent fault is discussed. A new definition of intermittent fault is put forward. Then the intermittent fault’s parameter framework is presented. After that, the Stochastic Petri Net (SPN) based formalization model for intermittent fault is constructed. Finally an application of the SPN formalization model is shown. The parameters for intermittent fault are computed based on the proposed model and a case study is presented. The result shows the validity of the model. The model could assist the further research such as intermittent fault diagnosis and prognostic of remaining life.

PL

Niezdatność przejściowa charakteryzuje wiele produktów i pociąga za sobą wysokie zagrożenie bezpieczeństwa oraz wysokie koszty eksploatacji. Obecnie istnieje wiele poglądów na temat pojęcia niezdatności przejściowej; nie stworzono jednak kompleksowego modelu parametrycznego pozwalającego w pełni opisać zjawisko niezdatności przejściowej. Nie skonstuowano także modelu formalnego, za pomocą którego można by opisać niezdatność przejściową w kategoriach matematycznych. W pracy omówiono koncepcję niezdatności przejściowej. Zaproponowano nową definicję tego pojęcia a następnie przedstawiono model parametryczny niezdatności przejściowej. Skonstruowano także model formalny niezdatności przejściowej oparty na stochastycznej sieci Petriego (SPN). Wreszcie, pokazano zastosowanie formalizacji SPN. Na podstawie zaproponowanego modelu obliczono parametry dla niezdatności przejściowej. Przedstawiono także studium przypadku. Otrzymane wyniki potwierdzają wiarygodność modelu. Opracowany model może być pomocny w dalszych badaniach dotyczących problemów, takich jak diagnozowanie niezdatności przejściowej czy prognozowanie pozostałego okresu użytkowania produktu.

2

On (m, n)-derivations of some algebras

Shen Q., Li J., Guo J.

Demonstratio Mathematica

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2014

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Vol. 47, nr 3

672--694

EN

Let A be a unital algebra, δ be a linear mapping from A into itself and m, n be fixed integers. We call δ an (m, n)-derivable mapping at Z, if mδ(AB) + nδ(BA) = mδ(A)B + mAδ(B) + nδ(B)A + nBδ(A) for all A, B (…) A with AB = Z. In this paper, (m, n)-derivable mappings at 0 (resp. IA (…) 0, I) on generalized matrix algebras are characterized. We also study (m, n)-derivable mappings at 0 on CSL algebras. We reveal the relationship between this kind of mappings with Lie derivations, Jordan derivations and derivations.

3

Fabrication and properties of SiNO continuous fiber reinforced BN wave-transparent composites

Cao F., Fang Z., Chen F., Shen Q., Zhang C.

Materials Science Poland

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2012

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Vol. 30, No. 2

137--142

EN

SiNO continuous fiber reinforced boron nitride (BN) wave-transparent composites (SiNOf /BN) have been fabricated by a precursor infiltration pyrolysis (PIP) method using borazine as the precursor. The densification behavior, microstructures, mechanical properties, and dielectric properties of the composites have been investigated. After four PIP cycles, the density of the composites had increased from 1.1 g-cm-3 to 1.81 g-cm-3. A flexural strength of 128.9 MPa and an elastic modulus of 23.5 GPa were achieved. The obtained composites have relatively high density and the fracture faces show distinct fiber pull-out and interface de-bonding features. The dielectric properties of the SiNOf /BN composites, including the dielectric constant of 3.61 and the dielectric loss angle tangent of 5.7-0-3, are excellent for application as wave-transparent materials.

4

Fabrication and thermal properties of Al2TiO5/Al2O3 composites

Li M., Chen F., Shen Q., Zhang L.

Materials Science Poland

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2010

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Vol. 28, No. 3

663--670

EN

Al2TiO5/Al2O3 composites with various Al2O3 contents were prepared. The phase compositions and microstructure evolution of the samples were observed via XRD and SEM, respectively. The thermal properties, including thermal expansion ratios and the erosion resistance of the Al2TiO5/Al2O3 composites to molten Al, were investigated. The experimental results show that the relative densities of the prepared Al2TiO5/Al2O3 composites are proportional to the Al2O3 content, and that the composite samples with high Al2TiO5 contents have good erosion resistance to molten Al.

5

Fabrication and dielectric properties of Si3N4-MgO-Al2O3 by spark plasma sintering technique

Li J., Chen F., Shen Q., Jiang H., Zhang L.

Materials Science Poland

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2007

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Vol. 25, No. 3

699--707

EN

In the present study, alfa-Si3N4 was prepared using MgO and Al2O3 as the sintering additives and spark plasma sintering (SPS) technique. The SPS sintering behaviour and mechanism have been discussed. The relationship between the content of sintering additives, sintering temperature, and relative densities of the samples have been analyzed. The phase composition was determined by XRD, the microstructures of the fracture surfaces were observed by SEM and the dielectric properties have been tested. The results suggest that when the sintering temperature is 1300-1500 oC, the content of sintering additives - 6-10%, the relative density of the sintered samples is 64-96%. When the sintering temperature reaches 1400 oC, the content of sintering additives 10%, the samples could be fully dense sintered (the relative density up to 95%) The sintering mechanism is liquid phase sintering. The electric permittivity of the sintered samples is 5-8 being in a close relationship with the relative density. The dielectric loss, influenced by the liquid phase, is less than 1×10-2.

6

Rough Set-Based Dimensionality Reduction for Supervised and Unsupervised Learning

Shen Q., Chouchoulas A.

International Journal of Applied Mathematics and Computer Science

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2001

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Vol. 11, no 3

583-601

EN

The curse of dimensionality is a damning factor for numerous potentially powerful machine learning techniques. Widely approved and otherwise elegant methodologies used for a number of different tasks ranging from classification to function approximation exhibit relatively high computational complexity with respect to dimensionality. This limits severely the applicability of such techniques to real world problems. Rough set theory is a formal methodology that can be employed to reduce the dimensionality of datasets as a preprocessing step to training a learning system on the data. This paper investigates the utility of the Rough Set Attribute Reduction (RSAR) technique to both supervised and unsupervised learning in an effort to probe RSAR's generality. FuREAP, a Fuzzy-Rough Estimator of Algae Populations, which is an existing integration of RSAR and a fuzzy Rule Induction Algorithm (RIA), is used as an example of a supervised learning system with dimensionality reduction capabilities. A similar framework integrating the Multivariate Adaptive Regression Splines (MARS) approach and RSAR is taken to represent unsupervised learning systems. The paper describes the three techniques in question, discusses how RSAR can be employed with a supervised or an unsupervised system, and uses experimental results to draw conclusions on the relative success of the two integration efforts.