1,721,798 research outputs found
Microstructural influence on sag resistance of Cr containing and Cr free spring steels
No full textThe effects of Cr addition and tempering temperature on mechanical properties, especially sag resistance, with respect to the microstructural evolution during tempering in 1.5%Si spring steels, were investigated by performing hardness tests, tensile tests, torsional Bauschinger tests, and examination by transmission electron microscopy. The results obtained showed that the sag resistance depended on the distribution of tempered carbides. With increasing tempering temperature, sag resistance increased to a maximum value at 350 degrees C and then decreased. The CI addition did not affect the behaviour of tempered carbides at low tempering temperatures, while at high temperatures, above 400 degrees C, the Cr addition reduced the coarsening rate of the cementite, resulting in finer particle distribution of the cementite. The Cr addition improved the sag resistance as well as the hardness at tempering temperatures above 400 degrees C, but it decreased the ratio of loop area in the torsional Bauschinger test (the sag resistance) to hardness, regardless of tempering temperature.X11sciescopu
The effect of strain rate on the anomalous peak of yield stress in beta-CuZn alloy
No full textX115sciescopu
Multisymbol data compression using a binary arithmetic coder
No full textA multisymbol data compression method using a binary arithmetic coder (BAC) is proposed. After representing symbols into a binary format. each bit is sequentially coded by the BAC using a chain rule. The proposed method provides a slightly better compression ratio and much faster processing time than Witten's multisymbol arithmetic coder
Near-lossless/lossless compression of error-diffused images using a two-pass approach
No full textThe current international standard, the Joint Bilevel Image Experts Group (JBIG), is a representative of a bilevel image compression algorithm. It compresses bilevel images with high performance, but it shows relatively low performance in compressing error-diffused halftone images. This paper proposes a new bilevel image compression for error-diffused images, which is based on Bayes' theorem. The proposed coding procedure consists of two passes. It groups 2 x 2 dots into a cell, where each cell is represented by the number of black dots and the locations of the black dots in the cell. The number of black dots in the cell is encoded in the first pass, and their locations are encoded in the second pass. The first pass performs a near-lossless compression, which can be refined to be lossless by the second pass. Experimental results show a high compression performance for the proposed method when it is applied to error-diffused images
Acoustic emission characteristics associated with macrostructures and plate orientations of an Al-Li 8090 alloy
No full textAn investigation was carried out to study the microstructural influence on the acoustic emission (AE) behavior during the tensile and fracture tests of an Al-Li 8090 alloy, and to correlate it with the deformation mechanisms of two different microstructures (the delta' microstructure and the S' + delta' microstructure), and of two different orientations (L and S). For the L-oriented specimens, continuous emissions were mostly produced in the delta' microstructure due to the shearing of coherent delta' precipitates, while in the S'+delta' microstructure the burst type emissions were dominant mainly due to the shearing or microcracking of large incoherent S' precipitates as well as the intergranular failure. The S-oriented specimens of both microstructures showed more burst emissions than the L-oriented ones, which resulted from the frequent occurrence of intergranular delamination in the L-oriented specimens. The K-AE values measured by AE method were well agreed with the K-IC values, implying that the K-AE could be considered as a quantitative and reliable parameter to evaluate the fracture toughness of a material. (C) 1997 Elsevier Science S.A.X113sciescopu
Fatigue crack propagation in Al-Li 8090 alloy at room (300K) and cryogenic (77K) temperatures
No full textX1111sciescopu
Progressive coding of error-diffused bilevel images
No full textWe propose a new method to compress error-diffused bilevel images with resolution scalability. This method is a combination of inverse halftoning and rehalftoning. For the inverse halftoning, we combine 2 x 2 dots into a single pixel of a resolution-reduced image, where each pixel has a multilevel value of 0, 1, 2, 3, and 4. After the inverse halftoning, the resolution-reduced multilevel image is halftoned by using an error diffusion algorithm. Thus, the resolution of the error-diffused bilevel images can be reduced by repetition of the inverse halftoning and rehalftoning processes. After reducing the image size, we encode an error-diffused bilevel image progressively from the lowest resolution image to the highest resolution image. To encode higher resolution images, we use the information in the previously coded lower resolution image. Though the compression ratios of the proposed algorithm are similar to those of progressive Joint Bilevel Image Processing Group (JBIG), the image quality of the resolution-reduced image from the proposed algorithm is much better than that from the progressive JBIG. (C) 2003 SPIE and IST
Quantitative elemental analysis of Fe-Zn-alloy coating by nondestructive method
No full textA quantitative analytical method of iron content in Fe-Zn-alloy coating by x-ray diffraction (XRD) spectrum was proposed. This work aimed to replace the wet chemical analysis of Fe-Zn-alloy coating with rapid and reproducible quantification by an XRD spectrum. Partial least-squares (PLS) model was utilized to differentiate the spectral characteristic as well as to quantify each component in XRD spectrum. Fifteen standard samples were prepared by heat treatment and verified by the relationship between wet chemical analyses and the XRD spectrum for iron content. The suggested method showed satisfactory precision and accuracy in the analysis of Fe-Zn-alloy coating. The accuracy for iron content in Fe-Zn-alloy coating was 0.17 wt%. Copyright (c) 2008 John Wiley & Sons, Ltd.X1111sciescopu
Prediction of differential drying shrinkage in concrete
No full textThe non-uniform moisture distribution in concrete causes the differential drying shrinkage. From this type of differential drying shrinkage, tensile stress occurs on the exposed surface of concrete structures and may result in crack formation. This residual stress is significantly affected by the creep of concrete. In this study, for the purpose of predicting the differential drying shrinkage, the analysis method was suggested, in which the creep of concrete was also considered. In addition, the differential drying shrinkage strain was measured at various positions in concrete by using embedded strain gauges. The internal drying shrinkage strain differs significantly according to the depth from exposed surface. The validity of analysis method was verified by comparing test results with analytical results. Finally it was found that analytical results were in good agreement with test results. (C) 1998 Elsevier Science Ltd
Activation mode dependent {10-12} twinning characteristics in a polycrystalline magnesium alloy
No full textThe {1 0 -1 2} extension twinning characteristics of magnesium alloys were found to be significantly influenced by the activation mode: tension parallel to the c-axis of the hexagonal close-packed unit cell or compression perpendicular to the c-axis. The Schmid factor criterion was successfully used to explain the activation of {1 0 -1 2} extension twin variants and its related twin morphology and texture evolution for each activation mode. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.X11104100sciescopu
- …
