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    Effect of crystallographic texture and twinning on the corrosion behavior of Mg alloys: A review

    , Article Journal of Magnesium and Alloys ; 2021 ; 22139567 (ISSN) Gerashi, E ; Alizadeh, R ; Langdon, T. G ; Sharif University of Technology
    National Engg. Reaserch Center for Magnesium Alloys  2021
    Magnesium and its alloys have gained significant popularity due to their light weight and their potential for use as bioresorbable materials. However, their application is limited in practice due to their relatively poor corrosion resistance. Several methods are available for improving the corrosion resistance of Mg alloys for bio-applications such as using different coatings, alloying, and modifying the microstructural parameters such as the grain size and the crystallographic texture. This review provides a comprehensive summary of the effects of crystallographic texture and twinning, as one of the most important deformation mechanisms of Mg and Mg alloys, on the corrosion behavior.... 

    Structure and texture image inpainting

    , Article Proceedings of the 2010 International Conference on Signal and Image Processing, ICSIP 2010, 15 December 2010 through 17 December 2010 ; 2010 , Pages 119-124 ; 9781424485949 (ISBN) Hesabi, S ; Jamzad, M ; Mahdavi Amiri, N ; Sharif University of Technology
    Inpainting refers to the task of filling in the missing or damaged regions of an image in an undetectable manner. We have an image to be reconstructed in a user-defined region. We use a fast decomposition method to obtain two components of the image, namely structure and texture. Reconstruction of each component is performed separately. The missing information in the structure component is reconstructed using a structure inpainting algorithm, while the texture component is repaired by a texture synthesis technique. To obtain the inpainted image, the two reconstructed components are composed together. Taking advantage of both the structure inpainting methods and texture synthesis techniques,... 

    Impact of phase transformation on mechanical properties anisotropy of commercially pure titanium

    , Article Materials and Design ; Volume 37 , 2012 , Pages 223-227 ; 02641275 (ISSN) Nasiri Abarbekoh, H ; Ekrami, A ; Ziaei Moayyed, A. A ; Sharif University of Technology
    Effects of microstructure and texture, before and after phase transformation, on the anisotropy of the mechanical properties and fracture behaviors of commercially pure titanium were studied. Before phase transformation, due to the split distribution of basal texture the activation of different deformation systems led to mechanical properties anisotropy. Although the fracture mechanism in both specimens was voids nucleation, growth and coalescence, the shape, size and distribution of dimples were affected by active deformation systems. However, after phase transformation, basal plains in most grains were aligned with the transverse direction. This texture component led to the activation and... 

    Effect of microstructural inhomogeneities on texture evolution in 90-10 Brass sheets

    , Article Journal of Materials Processing Technology ; Volume 182, Issue 1-3 , 2007 , Pages 440-444 ; 09240136 (ISSN) Salari, M ; Akbarzadeh, A ; Sharif University of Technology
    The control of texture and microstructure can be achieved by an appropriate thermomechanical treatment in industrial production. The effects of finish rolling temperature, cold reduction and annealing temperature on texture development and microstructure in Brass sheet were investigated. The role of deformation inhomogeneities on texture evolution has been considered. The formation of transition bands during hot rolling enforced the intensity of cube components. Shear bands increased the intensities of S and Cu components after cold rolling and at higher cold reductions. Transition from Cu to Y and Y to Bs was completed better because of mechanical twinning. Thermal twins annihilated the... 

    A new image texture extraction algorithm based on Matching Pursuit Gabor wavelets

    , Article 2005 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP '05, Philadelphia, PA, 18 March 2005 through 23 March 2005 ; Volume II , 2005 , Pages II740-II744 ; 15206149 (ISSN); 0780388747 (ISBN); 9780780388741 (ISBN) Yaghoobi, M ; Rabiee, H. R ; Ghanbari, M ; Shamsollahi, M. B ; Sharif University of Technology
    Feature vector extraction, based on local image texture, is a primitive algorithm for many other applications, like segmentation, clustering and identification. If these feature vectors are a good match to the human visual system (HVS), we can expect to get the appropriate results by using them. Gabor filters has been used for this purpose successfully. In this paper we introduce a novel refinement, with the use of Matching Pursuit (MP) to improve the Gabor based texture feature extractor. With this improvement, we show that the separability of different textures will increase. Another consideration in this work is computation complexity. Therefore, we limit the basis function set to reduce... 

    Development of cold rolling and intercritical annealing texture in two TRIP-aided steels

    , Article 14th International Conference on Textures of Materials, ICOTOM 14, Leuven, 11 July 2005 through 15 July 2005 ; Volume 495-497, Issue PART 1 , 2005 , Pages 513-518 ; 02555476 (ISSN); 087849975X (ISBN); 9780878499755 (ISBN) Emadodin, E ; Akbarzadeh, A ; Sharif University of Technology
    Trans Tech Publications Ltd  2005
    High strength TRIP-aided steel sheets with high formability and better ductility are of industrial interest. Texture control and retained austenite characterization are considered as the main factors with respect to the formability and ductility. In this work, the effect of cold rolling and intercritical annealing on texture development has been investigated for two TRTP-aided steel sheets, which are different in Si and Al content. Experiments show that the cold rolling extends the a and γ-fibers on these grades of steel. Intercretically annealing decreases the intensity of α-fiber and leads to sharpness of γ-fiber, especially for Al steel  

    Microstructure and texture development during friction stir processing of Al–Mg alloy sheets with TiO2 nanoparticles [electronic resource]

    , Article Materials Science and Engineering: A ; 27 May 2014, Volume 605, Pages 108–118 Khodabakhshi, F ; Simchi, A. (Abdolreza) ; Kokabi, A. H ; Nosko, M ; Simancik, F ; Svec, P ; Sharif University of Technology
    Aluminum matrix nanocomposites were fabricated by friction stir processing of Al–Mg alloy sheets with pre-placed TiO2 nanoparticles at a concentration of 2 to 6 vol%. Microstructural studies showed that solid state reactions between the metal matrix and TiO2 particles caused in situ formation of MgO and Al3Ti nanophases with an average size ~50 nm. These nanophases were homogenously distributed in an ultra-fine grain structure (0.2–2 µm) of the base metal. The results of pole figures evaluation obtained by electron back scattered diffraction studies revealed that the random orientation of initial annealed sheet was changed to components near to shear and silver texture in the friction stir... 

    Microstructural features, texture and strengthening mechanisms of nanostructured Al6063 alloy processed by powder metallurgy [electronic resource]

    , Article Journal of Materials Science and Engineering: A ; 15 May 2011, Volume 528, Issue 12, Pages 3981–3989 Asgharzadeh, H ; Simchi, A. (Abdolreza) ; Kim, H. S ; Sharif University of Technology
    Nanostructured AA6063 (NS-Al) powder with an average grain size of ∼100 nm was synthesized by high-energy attrition milling of gas-atomized AA6063 powder followed by hot extrusion. The microstructural features of the consolidated specimen were studied by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques and compared with those of coarse-grained AA6063 (CG-Al) produced by hot powder extrusion of gas-atomized powder (without using mechanical milling). The consolidated NS-Al alloy consisted of elongated ultrafine grains (aspect ratio of ∼2.9) and equiaxed nanostructured grains. A high fraction (∼78%) of high-angle grain boundaries with average... 

    Growth of ZNO nanostructures on porous silicon and oxidized porous silicon substrates

    , Article Brazilian Journal of Physics ; Volume 41, Issue 2-3 , 2011 , Pages 113-117 ; 01039733 (ISSN) Rajabi, M ; Dariani, R. S ; Iraji Zad, A ; Sharif University of Technology
    We have investigated an oxidation of substrate effect on structural morphology of zinc oxide (ZnO) rods. ZnO rods are grown on porous silicon (PS) and on thermally oxidized porous silicon substrates by carbothermal reduction of ZnO powder through chemical vapour transport and condensation. Porous silicon is fabricated by electrochemical etching of silicon in hydrofluoric acid solution. The effects of substrates on morphology and structure of ZnO nanostructures have been studied. The morphology of substrates is studied by atomic force microscopy in contact mode. The texture coefficient of each sample is calculated from X-ray diffraction data that demonstrate random orientation of ZnO rods on... 

    Effect of thermomechanical parameters on texture of 90-10 brass sheets

    , Article 14th International Conference on Textures of Materials, ICOTOM 14, Leuven, 11 July 2005 through 15 July 2005 ; Volume 495-497, Issue PART 1 , 2005 , Pages 755-760 ; 02555476 (ISSN); 087849975X (ISBN); 9780878499755 (ISBN) Salari, M ; Akbarzadeh, A ; Saffari, M. M ; Sharif University of Technology
    Trans Tech Publications Ltd  2005
    Optimized conditions of hot and cold rolling followed by annealing can result in a balance between recrystallization and rolling textures in order to reduce the planar anisotropy of brass sheets. In this work, the effect of finish rolling temperature, cold reduction and annealing temperature on texture development has been investigated. It is shown that uniform deformation at higher finishing temperature is responsible of formation of a severe Cube and G texture components. In contrast, mechanical twinnings are widely formed at low finishing temperatures. There is also a direct relation between the intensity of Cube component and the amount of cold reduction  

    Skin segmentation based on cellular learning automata

    , Article 6th International Conference on Advances in Mobile Computing and Multimedia, MoMM2008, Linz, 24 November 2008 through 26 November 2008 ; November , 2008 , Pages 254-259 ; 9781605582696 (ISBN) Abin, Ahmad Ali ; Fotouhi, M ; Kasaei, S ; Sharif University of Technology
    In this paper, we propose a novel algorithm that combines color and texture information of skin with cellular learning automata to segment skin-like regions in color images. First, the presence of skin colors in an image is detected, using a committee structure, to make decision from several explicit boundary skin models. Detected skin-color regions are then fed to a color texture extractor that extracts the texture features of skin regions via their color statistical properties and maps them to a skin probability map. Cellular learning automatons use this map to make decision on skin-like regions. The proposed algorithm has demonstrated true positive rate of about 83.4% and false positive... 

    Microstructure and texture evolution of Al-7075 alloy processed by equal channel angular pressing

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 25, Issue 5 , May , 2015 , Pages 1367-1375 ; 10036326 (ISSN) Shaeri, M. H ; Shaeri, M ; Salehi, M. T ; Seyyedein, S. H ; Djavanroodi, F ; Sharif University of Technology
    Nonferrous Metals Society of China  2015
    Equal channel angular pressing is an effective technique to control the texture and microstructure of metals and alloys. Texture and microstructure of an Al-7075 alloy subjected to repetitive equal channel angular pressing through a 90° die were evaluated by X-ray diffractometer and orientation imaging microscopy. It is observed that processing through different routes leads to different types of textures, in both qualitative and quantitative senses. The texture calculation by Labotex software reveals that texture strengthens after the first pass and weakens by progressing ECAP process up to 4 passes. Microstructure investigations show that after 4 passes of equal channel angular pressing... 

    The correlation of stir zone texture development with base metal texture and tool-induced deformation in friction stir processing of severely deformed aluminum

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 48, Issue 1 , 2017 , Pages 188-197 ; 10735623 (ISSN) Sarkari Khorrami, M ; Kazeminezhad, M ; Miyashita, Y ; Kokabi, A. H ; Sharif University of Technology
    Springer Boston  2017
    The texture development during friction stir processing (FSP) of 1050 aluminum severely deformed at the strain magnitude of 2.32 was comprehensively discussed. It was observed that the component B¯ of the ideal shear texture along with the cube texture was developed in the severely deformed base metal. The effects of base metal texture on the texture development of stir zone, thermo-mechanically affected zone, and heat-affected zone during FSP were examined. Also, the developed texture components in the vicinity of the FSP tool and the stir zone were correlated to the deformation induced by the rotating tool which consisted of pin and shoulder. The observed texture components in the... 

    Anisotropy in the quasi-static and cyclic behavior of ZK60 extrusion: Characterization and fatigue modeling

    , Article Materials and Design ; Volume 160 , 2018 , Pages 936-948 ; 02641275 (ISSN) Pahlevanpour, A. H ; Karparvarfard, S. M. H ; Shaha, S. K ; Behravesh, S. B ; Adibnazari, S ; Jahed, H ; Sharif University of Technology
    Elsevier Ltd  2018
    The quasi-static and strain-controlled fatigue characteristics of ZK60 extrusion have been investigated along three different directions: the extrusion direction (ED), the radial direction (RD), and 45° to the extrusion direction (45°). The quasi-static response showed symmetric behavior for the samples tested along RD and 45° whereas the ED samples manifested completely asymmetric behavior. Although the ED samples exhibited longer fatigue lives than the RD and 45° in the high cycle fatigue, the fatigue lives in the low cycle fatigue regime were similar. The texture measurement indicated a sharp basal texture along ED, explaining its asymmetric behavior. Higher tensile mean stress and less... 

    Empirical study on effect of surface texture and grain size on displacement measurement of optical flow sensors

    , Article 2014 2nd RSI/ISM International Conference on Robotics and Mechatronics, ICRoM 2014 ; Oct , 2014 , p. 493-497 ; ISBN: 9781479967438 Azizi, A ; Vossoughi, G ; Sharif University of Technology
    Although, the optical flow sensors which are used in optical mouse have high resolution in measuring displacement, their error refrain us from a precise and reliable measurement. Besides, these sensors require calibration based on the surface. Their error has different sources and the most important is surface texture in micro level. In this research, we have worked to find surface conditions on which sensor measurement is more precise. For this aim, we used an 800 DPI low cost optical flow sensor. For making different surface textures and grains, we printed different textures with 600 and 1200DPI resolution on white paper with certain length. Then we used optical flow sensor for measuring... 

    Deformation mode dependency of stable orientations: From plane strain compression to equibiaxial tension

    , Article Philosophical Magazine ; Volume 95, Issue 7 , Feb , 2015 , Pages 794-803 ; 14786435 (ISSN) Hajian, M ; Khajeh Salehani, M ; Assempour, A ; Mehdigholi, H ; Sharif University of Technology
    Taylor and Francis Ltd  2015
    Prediction of stable orientations is a key subject in the crystal plasticity literature. This work deals with the effects of deformation mode on the resulted stable orientations and texture evolution of FCC materials. The simulations are based on the numerical procedure developed by the authors in previous works in which, a rate-sensitive crystal plasticity model with Secant hardening law was employed. The resulting non-linear system of equations is solved by the modified Newton-Raphson method. In order to obtain the stable orientations for a deformation mode, initial orientations evenly spaced in the Euler space are selected and their evolution into the stable orientations is tracked. The... 

    Quantization-unaware double JPEG compression detection

    , Article Journal of Mathematical Imaging and Vision ; Volume 54, Issue 3 , 2016 , Pages 269-286 ; 09249907 (ISSN) Taimori, A ; Razzazi, F ; Behrad, A ; Ahmadi, A ; Babaie Zadeh, M ; Sharif University of Technology
    Springer New York LLC 
    The current double JPEG compression detection techniques identify whether or not an JPEG image file has undergone the compression twice, by knowing its embedded quantization table. This paper addresses another forensic scenario in which the quantization table of a JPEG file is not explicitly or reliably known, which may compel the forensic analyst to blindly reveal the recompression clues. To do this, we first statistically analyze the theory behind quantized alternating current (AC) modes in JPEG compression and show that the number of quantized AC modes required to detect double compression is a function of both the image’s block texture and the compression’s quality level in a fresh... 

    Crowded scene object tracking in presence of Gaussian white noise using undecimated wavelet features

    , Article 2007 9th International Symposium on Signal Processing and its Applications, ISSPA 2007, Sharjah, 12 February 2007 through 15 February 2007 ; 2007 ; 1424407796 (ISBN); 9781424407798 (ISBN) Khansari, M ; Rabiee, H. R ; Asadi, M ; Ghanbari, M ; Sharif University of Technology
    In this paper, we propose a new noise robust algorithm for object tracking in the crowded video scenes. The algorithm exploits the properties of undecimated wavelet packet transform (UWPT) coefficients and texture analysis to track arbitrary objects. The coefficients of the UWPT of a user-specified region at the reference frame construct a Feature Vector (FV) for every pixel in that region. Optimal search for the best match of the region in successive frames is then performed by using the generated FVs inside an adaptive search window. Adaptation of the search window is achieved by inter-frame texture analysis to find the direction and speed of the object motion. Noise robustness has been... 

    Large-scale image annotation using prototype-based models

    , Article ISPA 2011 - 7th International Symposium on Image and Signal Processing and Analysis ; 2011 , Pages 449-454 ; 9789531841597 (ISBN) Amiri, S. H ; Jamzad, M ; European Association for Signal Processing (EURASIP); IEEE Signal Processing Society; IEEE Region 8; IEEE Croatia Section; IEEE Croatia Section Signal Processing Chapter ; Sharif University of Technology
    Automatic image annotation is a challenging problem in the field of image retrieval. Dealing with large databases makes the annotation problem more difficult and therefore an effective approach is needed to manage such databases. In this work, an annotation system has been developed which considers images in separate categories and constructs a profiling model for each category. To describe an image, we propose a new feature extraction method based on color and texture information that describes image content using discrete distribution signatures. Image signatures of one category are partitioned using spectral clustering and a prototype is determined for each cluster by solving an... 

    Skin detection using contourlet texture analysis

    , Article 2009 14th International CSI Computer Conference, CSICC 2009, 20 October 2009 through 21 October 2009, Tehran ; 2009 , Pages 367-372 ; 9781424442621 (ISBN) Fotouhi, M ; Rohban, M. H ; Kasaei, S ; Sharif University of Technology
    A combined texture- and color-based skin detection is proposed in this paper. Nonsubsampled contourlet transform is used to represent texture of the whole image. Local neighbor contourlet coefficients of a pixel are used as feature vectors to classify each pixel. Dimensionality reduction is addressed through principal component analysis (PCA) to remedy the curse of dimensionality in the training phase. Before texture classification, the pixel is tested to determine whether it is skin-colored. Therefore, the classifier is learned to discriminate skin and non-skin texture for skin colored regions. A multi-layer perceptron is then trained using the feature vectors in the PCA reduced space. The...