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Adaptive Medical Image Compression Based on Lossy and Lossless Embedded Zerotree Methods
( Sid Ahmed Elhannachi ),( Nacera Benamrane ),( Taleb-ahmed Abdelmalik ) 한국정보처리학회 2017 Journal of information processing systems Vol.13 No.1
Since the progress of digital medical imaging techniques, it has been needed to compress the variety of medical images. In medical imaging, reversible compression of image`s region of interest (ROI) which is diagnostically relevant is considered essential. Then, improving the global compression rate of the image can also be obtained by separately coding the ROI part and the remaining image (called background). For this purpose, the present work proposes an efficient reversible discrete cosine transform (RDCT) based embedded image coder designed for lossless ROI coding in very high compression ratio. Motivated by the wavelet structure of DCT, the proposed rearranged structure is well coupled with a lossless embedded zerotree wavelet coder (LEZW), while the background is highly compressed using the set partitioning in hierarchical trees (SPIHT) technique. Results coding shows that the performance of the proposed new coder is much superior to that of various state-of-art still image compression methods.
Lamia Sid Ali,Moussa Brada,Marie-Laure Fauconnier,Tierry Kenne 한국생약학회 2018 Natural Product Sciences Vol.24 No.1
The present study deals with the determination of optimal values of operating parameters such as the temperature of heating, the mass of the plant material and the volume of water leading to the best yield of electromagnetic induction (EMI) heating extraction of Algerian Thymus fontanesii essential oil. After an appropriate choice of the three critical variables, eight experiments leaded to a mathematical model as a first-degree polynomial presenting the response function (yield) in the relation to the operating parameters. From the retained model, we were able to calculate the average response, the different effects and their interactions. The maximum of essential oil recovery percentage relative to the initial mass of plant material was 1.69%, and was obtained at (140 oC, 250 g and 4.5 L). The chemical composition of the Algerian T. fontanesii essential oil under the obtained optimal conditions (140 oC, 250 g and 4.5 L), determined by GC/MS and GC/FID, reveled of the presence of major components such as: carvacrol (70.6 ? 0.1%), followed by p-cymene (8.2 ? 0.2%).
Meftah Sid Ahmed,Abdelouahed Tounsi,Pham Van Vinh 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4
In this paper, the nonlinear buckling analysis of rectangular hollow sections (RHS) beams considering distortional and the shear fl exibility deformation eff ects is investigated. The kinematic model is based on the incorporation of non-classical terms, related to shear fl exibility, according to Timoshenko model and distortion and warping. This analysis is carried out by proposing a new 3D fi nite element, formulated in the context of large torsion, incorporating fl exural torsion, and distortion coupling eff ects. A 3D RHS beam element with two nodes and eleven degrees of freedom per node is proposed to perform the nonlinear buckling analysis. For this aim, the arc-length method is employed as a solution strategy to solve the nonlinear equilibrium equations, established as a function of the trigonometric functions of the twist angle. Many examples are proposed to check the validity of the proposed 3D fi nite element and the numerical procedure, either in pre-and postbuckling states. The present numerical results are compared to those of the commercial software ABAQUS using the brick fi nite elements. The incidences of the compressive load and the incorporated lateral stiff eners in the RHS beams in pre- and post-buckling behaviour are studied.
Mohammed Sid Ahmed Houari,Aicha Bessaim,Fabrice Bernard,Abdelouahed Tounsi,S. R. Mahmoud 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.1
A size-dependent novel hyperbolic shear deformation theory of simply supported functionally graded beams is presented in the frame work of the non-local strain gradient theory, in which the stress accounts for only the nonlocal strain gradients stress field. The thickness stretching effect (<i>ε<sub>z</sub></i> ≠ 0) is also considered here. Elastic coefficients and length scale parameter are assumed to vary in the thickness direction of functionally graded beams according to power-law form. The governing equations are derived using the Hamilton principle. The closed-form solutions for exact critical buckling loads of nonlocal strain gradient functionally graded beams are obtained using Navier's method. The derived results are compared with those of strain gradient theory.
Shear correction factors of a new exponential functionally graded porous beams
Mohammed Sid Ahmed Houari,Aicha Bessaim,Tarek Merzouki,Ahmed Amine Daikh,Aman Garg,Abdelouahed Tounsi,Mohamed A. Eltaher,Mohamed-Ouejdi Belarbi 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.1
This article introduces a novel analytical model for examining the impact of porosity on shear correction factors (SCFs) in functionally graded porous beams (FGPB). The study employs uneven and logarithmic-uneven modified porositydependent power-law functions, which are distributed throughout the thickness of the FGP beams. Additionally, a modified exponential-power law function is used to estimate the effective mechanical properties of functionally graded porous beams. The correction factor plays a crucial role in this analysis as it appears as a coefficient in the expression for the transverse shear stress resultant. It compensates for the assumption that the shear strain is uniform across the depth of the cross-section. By applying the energy equivalence principle, a general expression for static SCFs in FGPBs is derived. The resulting expression aligns with the findings obtained from Reissner’s analysis, particularly when transitioning from the two-dimensional case (plate) to the onedimensional case (beam). The article presents a convenient algebraic form of the solution and provides new case studies to demonstrate the practicality of the proposed formulation. Numerical results are also presented to illustrate the influence of porosity distribution on SCFs for different types of FGPBs. Furthermore, the article validates the numerical consistency of the mechanical property changes in FG beams without porosity and the SCF by comparing them with available results.
Adaptive Medical Image Compression Based on Lossy and Lossless Embedded Zerotree Methods
Elhannachi, Sid Ahmed,Benamrane, Nacera,Abdelmalik, Taleb-Ahmed Korea Information Processing Society 2017 Journal of information processing systems Vol.13 No.1
Since the progress of digital medical imaging techniques, it has been needed to compress the variety of medical images. In medical imaging, reversible compression of image's region of interest (ROI) which is diagnostically relevant is considered essential. Then, improving the global compression rate of the image can also be obtained by separately coding the ROI part and the remaining image (called background). For this purpose, the present work proposes an efficient reversible discrete cosine transform (RDCT) based embedded image coder designed for lossless ROI coding in very high compression ratio. Motivated by the wavelet structure of DCT, the proposed rearranged structure is well coupled with a lossless embedded zerotree wavelet coder (LEZW), while the background is highly compressed using the set partitioning in hierarchical trees (SPIHT) technique. Results coding shows that the performance of the proposed new coder is much superior to that of various state-of-art still image compression methods.