Feature extraction and optimized support vector machine for severity fault diagnosis in ball bearing
, Pages: 167-176
Tawfik Thelaidjia, Abdelkrim Moussaoui and Salah Chenikher PDF (650K)
Abstract: In this paper, a method for severity fault diagnosis of ball bearings is presented. The method is based on wavelet packet transform (WPT), statistical parameters, principal component analysis (PCA) and support vector machine (SVM). The key to bearing faults diagnosis is features extraction. Hence, the proposed technique consists of preprocessing the bearing fault vibration signal using statistical parameters and energy obtained through the application of Db8- WPT at the third level of decomposition. After feature extraction from vibration signal, PCA is employed for dimensionality reduction. Finally, particle swarm optimization with passive congregation-based support vector machine is used to classify seven kinds of bearing faults. The classification results indicate the effectiveness of the proposed method for severity faults diagnosis in ball bearings.
Keywords: Fault Diagnosis, Particle Swarm Optimization with Passive Congregation, Principal Component Analysis, Statistical Parameters, Support Vector Machine, Wavelet Packet Transform
Introducing resilience factor in the structure as a new control coefficient
, Pages: 177-186
Fereydoon Omidinasab, Shima Najjar, Hossein Rezaei and Peyman Beiranvand PDF (650K)
Abstract: When a structure is influenced by the earthquake external force, some energy imposed to the structure is dissipated and remained energy causes structure displacements. Dissipated energy in the structure depends on the type of structure and its optimal engineering design. In any typical structure, the type of connections, stiffness of structure, dampers, place of windfall and damper and other factors play significant role in the amount of dissipated energy. This article introduces a new resilience factor which is a function of energy dissipation factors of input seismic energy. Mathematical equations are presented for this factor and its limits are determined for different periods. The applicability of the proposed factor is also investigated for two typical structural examples.
Keywords: Dissipated energy, Optimal design, Jump factor, Practical examples
Three dimensional viscoelastic medium under thermal shock
, Pages: 187-200
Abhik Sur and M. Kanoria PDF (650K)
Abstract: This article deals with the thermoelastic interaction in a three-dimensional homogeneous and isotropic viscoelastic medium under the Dual-phase-lag model of generalized thermoelasticity. The resulting non-dimensional coupled equations are applied to a specific problem of a half-space whose surface is traction-free and is subjected to a time-dependent thermal shock. The analytical expressions for the displacement components, stress, temperature and strain are obtained in the physical domain by employing normal mode analysis. These expressions are also calculated for a copper-like material and have been depicted graphically. Discussions have been made to highlight the effect of viscosity on the studied field. The phenomenon of a finite speed of propagation is observed for each field. Also, if the effect of viscosity is neglected, the results agree with the existing literature.
Keywords: Generalized thermoelasticity, Dual-phase-lag thermoelastic model, Kelvin-Voigt-model, Finite wave speed, Normal mode analysis
An effective combination of finite element and differential quadrature method for analyzing of plates partially resting on elastic foundation
, Pages: 201-218
Mehdi Dehghan, Mohammad Zamani Nejad and Amin Moosaie PDF (650K)
Abstract: This paper is concerned with the vibration and stability analysis of thick rectangular plates resting on elastic foundation, which is distributed over the particular area of the plate. A two-parameter (Pasternak) model is considered to describe the elastic foundation. The eigenvalue problem in 3-D domain is numerically solved by a combination of the finite element and differential quadrature method (DQM). The energy principle is employed to derive the governing equations in the framework of three-dimensional, linear and small strain theory of elasticity. The in-plane domain of the problem is discretized using two-dimensional finite elements and spatial derivatives of equations in the thickness direction are discretized in strong-form using DQM. As a first endeavor, the mixed FE-DQ method has been employed for 3-D buckling and free vibration analysis of rectangular thick plates partially supported by an elastic foundation. The accuracy of obtained results is validated by comparing to the few analytical solutions in the literature.
Keywords: FE-DQ method, Stability and free vibration, Thick plates, Partial elastic foundation
Changes in the topology of a concrete porous space in interactions with the external medium
, Pages: 219-225
Yury Mikhaylovich Bazhenov, Vladimir Trofimovich Erofeev, Vladimir Ivanovich Rimshin, Sergey Vitalyevich Markov and Vladimir Leonidovich Kurbatov PDF (650K)
Abstract: The article is devoted to some aspects of research of hostile environment influence on the concrete durability. The mechanism of formation of chaotically diversified difficult structure is described. Chemical interactions of cement with active components of diffusion in steam space are examined. Measures for receiving conditions under which the volume of products of reaction will be equal to the volume of the reacted alkaline components of a cement stone are offered. High-quality and quantitative changes in a pore space, which are irrespective of density and the relative molecular mass of reaction products are described. Besides, movement and distribution of gaseous products of reaction in volumes of a cement stone are simulated. Reasonable integrated dependences of influence of aggressive environment on various types of concrete surfaces are given. The methods of corrosion control offered in article allow substantially to lower or absolutely to exclude adverse effect of hostile environment on concrete and reinforced concrete structures already at a stage of selection of composition of concrete mix. In this case service life of concrete and reinforced concrete structures will increase.
Keywords: Corrosion, Concrete, Capillary, Carbonization time, Mathematical model
Guillotine side trimming shear machine: A case study of plate mill in Bhilai steel plant
, Pages: 226-234
Murli Krishan Bairagi, Amit Kumar Sinha and Ankush Anand PDF (650K)
Abstract: Double-sided trimming shear machine is used for longitudinal both–sided trimming of steel plates and simultaneous scraping of trimmed edges at specific length. Side trimming shear (STS) executes the most vital role in increasing the productivity of plate mill and due to its feature, efficiency of plate mill division is enormously increases. In general, frequency of the occurrence of breakdown in STS machine is a most challenging task when STS performs side trimming and scrap cutting machining process. Bhilai Steel Plant (Steel Authority of India at Bhilai) in India is continuously facing a problem due to breakdown of STS machine. The use of separate knife for side trimming and scrap cutting reduces the possibility of scrap jamming which is a major reason for breakdown of STS machine. Researchers and practitioners also suggest the use of arc guillotine shear for side trimming and straight guillotine shear for scrap cutting for minimizing the breakdown in STS machine. The aim of this study is to describe the problems faced by the steel industry as well as the necessary steps which should be taken for improvement of the productivity of STS machine and also it has made contribution to Bhilai Steel Plant by its growth and prosperity. The methodology of study is purely qualitative and the results point out the problems, its implications, steps taken to improve the overall productivity of Bhilai steel plant.
Keywords: Trimming mechanism, Bhilai steel plant, Kinematics of machine, Shear force
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