Tribological failure analyses of automotive engine blocks subjected to sliding wear damage

This thesis presents the tribological failure analyses of sliding wear damage on a linerless engine block made of a new near-eutectic aluminum silicon alloy Al-11%Si. The stereological, optical metallographic, SEM/EDS and surface profile examinations and microhardness testing were used to investigate the wear performance and the types of sliding damages, as well as the microstructure variation, phase fragmentation underneath the damage surface. The effect of the different honing processes of cylinder bore surface preparation on bore surface morphology and quality was studied to understand the original surface features before engine testing. Excepting virgin areas on the bore surface, five types of sliding damages were identified as normal wear, severe scratch, comets wear, burnishing wear and top land contact wear on the scuffed cylinder bore. The wear damage mechanisms were discussed based upon subsurface microstructure variation, especially, phase fragmentation behavior. (Abstract shortened by UMI.)Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2006 .Y83. Source: Masters Abstracts International, Volume: 45-01, page: 0444. Thesis (M.A.Sc.)--University of Windsor (Canada), 2006

Centrifugal pump fault detection based on SWT and SVM

Centrifugal pumps, like other rotating equipment, produce vibration signals during operation. Vibration signals often contain pump state information. Therefore, we can obtain pump state information by using appropriate signal processing methods. Synchrosqueezing wavelet transform (SWT) is a new time-frequency analysis technology. It is an algorithm for rebuilding time-frequency signals, which is similar to the empirical mode decomposition method. It can improve the time-frequency resolution of the signal compared with wavelet transform. In this paper, the SWT is used to analyze the vibration signal of centrifugal pump and extract characteristics. The data shows that the SWT can effectively extract the information of signal in time domain and frequency domain. Then we use the Support Vector Machine (SVM) to classify the features and realize the fault diagnosis of centrifugal pump. The result proves that the fault diagnosis method based on the SWT and SVM

Rolling bearing fault detection based on local characteristic-scale decomposition and teager energy operator

In this paper, a rolling bearing fault detection method based on Local Characteristic-scale Decomposition (LCD) and Teager Energy operator (TEO) is proposed. Vibration signals is related to the bearing fault. However, the vibration signal of rolling bearing is nonlinear and has multiple components, which makes it difficult to analyze the signals by using traditional method such as the fast Fourier transform (FFT). LCD, a recently developed signal decomposition method, is especially capable for dealing with the complex signal by decomposing it into several intrinsic scale components (ISC). Furthermore, to extract fault diagnosis of the components, we used TEO to demodulate each ISC. The energy of fault feature frequencies was extracted as fault vector. The result shows that the method successfully diagnoses bearing fault

(Z)-N-{(E)-10-[(2,6-Diisopropyl­phen­yl)­imino]-9,10-dihydro­phenanthren-9-yl­idene}-2,6-dimethyl­aniline

The title compound, C34H34N2, adopts a Z,E configuration with respect to the N=C—C=N backbone, with an N—C—C—N torsion angle of 41.1 (4)° The dihedral angle between the benzene rings in the 9,10-dihydro­phenanthrene moiety is 18.0 (1)°

On a new class of Finsler metrics

In this paper, the geometric meaning of (alpha,beta)-norms is made clear. On this basis, we introduce a new class of Finsler metrics called general (alpha,beta)-metrics, which are defined by a Riemannian metric and an 1-form. These metrics not only generalize original (alpha,beta)-metrics naturally, but also include some metrics structured by R. Bryant. The notion of general (alpha,beta)-metrics is one of the original ideas belongs to the first author(another one is beta-deformations intruduced in the paper "Deformations and Hilbert's Fourth Problem"). We believe that the researches on general (alpha,beta)-metrics will enrich Finsler geometry and the approaches offer references for further study. But it seems that the classical methods suitable for (alpha,beta)-metrics may not be suitable for them, the idea used in this paper, which is closely related to beta-deformations, is non-classical. Any communication or suggestion is welcome.Comment: 16 page

Preparation and Micro Mechanical Properties of Nano-Al2O3 Particles Strengthened Ni-based Composite Coatings

AbstractNi-based composite solution containing nano-Al2O3 particles was prepared by high-energy mechanical and chemical processes. The microstructure and nano-particle content of nano-Al2O3/Ni composite coatings were determined by SEM, EDS and TEM. The micro mechanical properties were tested by nano-indentation technique, and the strengthening mechanism was analyzed. The results show that 85 percent of particles in the solution are dispersed in size of nano meter, nano-particles co-deposited in the coating increases by a factor of 53 percent and the structure of the composite coating is more compact and uniform than that of Ni coating. Nano-Al2O3/Ni coatings exhibit excellent micro mechanical properties, the nanohardness and Young's modulus are 7.04GPa and 225GPa respectively, which are attributed to finer crystals strengthening, dispersion strengthening and high- density dislocations strengthening

Improved Statistical Analysis for Array CGH-Based DNA Copy Number Aberrations

Array-based comparative genomic hybridization (aCGH) allows measuring DNA copy number at the whole genome scale. In cancer studies, one may be interested in identifying DNA copy number aberrations (CNAs) associated with certain clinicopathological characteristics such as cancer metastasis. We proposed to define test regions based on copy number pattern profiles across multiple samples, using either smoothed log2-ratio or discrete data of copy number gain/loss calls. Association test performed on the refined test regions instead of the probes has improved power due to reduced number of tests. We also compared three types of measurement of copy number levels, normalized log2-ratio, smoothed log2-ratio, and copy number gain or loss calls in statistical hypothesis testing. The relative strengths and weaknesses of the proposed method were demonstrated using both simulation studies and real data analysis of a liver cancer study

Factors influencing college students' online rumor refuting behavior during major public health crises: the moderating effect of group norms

This study integrates SOR (Stimuli-Organism-Response) theoretical framework and rational behavior theory within a theoretical framework, incorporating group norms as a moderating factor to investigate the psychological mechanisms influencing Chinese college students' online rumor-refutation behavior amidst public health crises. Using the structural equation modeling research method, data was collected via questionnaires from 1,254 participants in the context of the COVID-19 pandemic. The findings indicate that both online and offline information seeking are positively correlated with college students' attitudes and subjective norms. Moreover, the attitudes and subjective norms of college students are positively correlated with the online rumor refuting behavior. Furthermore, group norms serve to strengthen the connection between college students' attitudes and their engagement in online refuting rumors. These results illuminate the psychological underpinnings driving college students' online rumor-refuting actions, offering practical and policy implications for effectively managing rumor behaviors