Enhanced Image Fusion Technique for Segmentation of Tumor using Fuzzy

This paper presents the MRI brain diagnosis support system for structure segmentation and its analysis using spatial fuzzy clustering algorithm. The method is proposed to segment normal tissues such as white Matter, Gray Matter, Cerebrospinal Fluid and abnormal tissue like tumor part from MR images automatically. These MR brain images are often corrupted with Intensity Inhomogeneity artifacts cause unwanted intensity variation due to non- uniformity in RF coils and noise due to thermal vibrations of electrons and ions and movement of objects during acquisition which may affect the performance of image processing techniques used for brain image analysis

Advances in Mechanical Metamaterials for Vibration Isolation: A Review

The adverse effect of mechanical vibration is inevitable and can be observed in machine components either on the long- or short-term of machine life-span based on the severity of oscillation. This in turn motivates researchers to find solutions to the vibration and its harmful influences through developing and creating isolation structures. The isolation is of high importance in reducing and controlling the high-amplitude vibration. Over the years, porous materials have been explored for vibration damping and isolation. Due to the closed feature and the non-uniformity in the structure, the porous materials fail to predict the vibration energy absorption and the associated oscillation behavior, as well as other the mechanical properties. However, the advent of additive manufacturing technology opens more avenues for developing structures with a unique combination of open, uniform, and periodically distributed unit cells. These structures are called metamaterials, which are very useful in the real-life applications since they exhibit good competence for attenuating the oscillation waves and controlling the vibration behavior, along with offering good mechanical properties. This study provides a review of the fundamentals of vibration with an emphasis on the isolation structures, like the porous materials (PM) and mechanical metamaterials, specifically periodic cellular structures (PCS) or lattice cellular structure (LCS). An overview, modeling, mechanical properties, and vibration methods of each material are discussed. In this regard, thorough explanation for damping enhancement using metamaterials is provided. Besides, the paper presents separate sections to shed the light on single and 3D bandgap structures. This study also highlights the advantage of metamaterials over the porous ones, thereby showing the future of using the metamaterials as isolators. In addition, theoretical works and other aspects of metamaterials are illustrated. To this end, remarks are explained and farther studies are proposed for researchers as future investigations in the vibration field to cover the weaknesses and gaps left in the literature

Resilience and Toughness Behavior of 3D-Printed Polymer Lattice Structures: Testing and Modeling

This research focuses on the energy absorption capability of additively manufactured or 3D printed polymer lattice structures of different configurations. The Body Centered Cubic (BCC) lattice structure is currently being investigated by researchers for energy absorption applications. For this thesis, the BCC structure is modified by adding vertical bars in different arrangements to create three additional configurations. Four designs or sets of the lattice structure are selected for comparison including BCC, BCC with vertical bars added to all nodes (BCCV), BCC with vertical bars added to alternate nodes (BCCA), and BCC with gradient arrangements of vertical bars (BCCG). Both experimental and finite element modeling approaches are used to understand the load-displacement as well as energy absorption behavior of all four configurations under both quasi- static compression and low-velocity impact loadings. Once designed in SolidWorks, all four sets of samples were prepared using Acrylonitrile Butadiene Styrene (ABS) polymer material on a Stratasys uPrint 3D printer. The Instron universal testing machine was used for the quasi-static loading test whereas an in-house built ASTM Standard D7136 drop tester was used to capture the impact response. For impact samples, sandwich panels were fabricated using the 3D printed ABS lattice core structures. In this case, four Kevlar face sheets were attached to the lattice core structure using a two-part epoxy adhesive. The absorbed energy was found by integrating the area under the load-displacement curve for both compression and impact tests. To interpret the results, Specific Energy Absorption (SEA) that is the absorbed energy over the mass, should be considered. Moreover, the investigation of the SEA was also performed using Finite Element Analysis (FEA) for comparison. ANSYS Workbench was used to predict the behavior of the lattice structures under compression load. However, Abaqus Dynamic Explicit was used to capture the low-velocity impact response of sandwich panels with printed lattice cores. It is observed from both experimental and FEA data that selective placement of vertical support struts in the unit-cell influences the absorption energy of the lattice structures. In the compression test, the highest SEA was captured for the BCCV specimen which has more weight when compared with the others. However, the highest SEA was captured in impact test for the BCCA specimen

Compression Behavior of Three-Dimensional Printed Polymer Lattice Structures

This paper focuses on the compression behavior of additively manufactured or three-dimensional printed polymer lattice structures of different configurations. The body-centered cubic lattice unit cell, which has been extensively investigated for energy absorption applications, is the starting point for this research. In this study, the lattice structure based on the body-centered cubic unit cell was modified by adding vertical struts in different arrangements to create three additional configurations. Four lattice structure designs were selected for comparison: the basic unit cell (body centered cubic), body centered cubic with vertical struts added to all nodes in the lattice, body centered cubic with vertical struts added to alternate nodes in the lattice, and body centered cubic with gradient in the number of vertical bars in the lattice. Samples of all four designs were prepared using acrylonitrile-butadiene-styrene polymer by three-dimensional printing. The stiffness, failure loads, and energy absorption behaviors of all four configurations were determined under quasi-static compression loading. Specific properties were calculated by normalizing the test properties by the sample mass. It is observed from experimental data that selective placement of vertical support struts in the unit cell influences both the absolute and specific mechanical properties of lattice structures

Report on a working visit to the cocoa research unit in Trinidad, 7 to April 1995

L'objectif de cette mission était d'évaluer les activités de deux chercheurs du CIRAD-CP, basés au CRU (Cocoa Research Unit), ainsi que les activités financées en partie par un projet FIC intitulé "Etude et caractérisation de cacaoyers particulièrement intéressants pour la sélection". Concernant les études des isoenzymes, les systèmes sont maintenant opérationnels. Les études RAPD relatives aux choix des primers seront achevés dans 2 à 3 mois, la caractéristion d'environ 200 génotypes sera achevée dans 7 à 9 mois. D'importants progrès ont été obtenus au cours des deux dernières années pour l'étude de la résistance au balai de sorcière : 52 clones ICS ont été évalués (observation au champ, innoculation en pépinière). Une nouvelle méthode d'innoculation rapide a été mise au point et semble donner des résultats prometteurs. Des conclusions et des recommandations sur les activités des chercheurs sont données. L'auteur évoque également le problèmes des erreurs d'identifications ainsi qu'une stratégie de mise au point d'une core collection dans une banque de gène

Advances in Mechanical Metamaterials for Vibration Isolation: A Review

The adverse effect of mechanical vibration is inevitable and can be observed in machine components either on the long- or short-term of machine life-span based on the severity of oscillation. This in turn motivates researchers to find solutions to the vibration and its harmful influences through developing and creating isolation structures. The isolation is of high importance in reducing and controlling the high-amplitude vibration. Over the years, porous materials have been explored for vibration damping and isolation. Due to the closed feature and the non-uniformity in the structure, the porous materials fail to predict the vibration energy absorption and the associated oscillation behavior, as well as other the mechanical properties. However, the advent of additive manufacturing technology opens more avenues for developing structures with a unique combination of open, uniform, and periodically distributed unit cells. These structures are called metamaterials, which are very useful in the real-life applications since they exhibit good competence for attenuating the oscillation waves and controlling the vibration behavior, along with offering good mechanical properties. This study provides a review of the fundamentals of vibration with an emphasis on the isolation structures, like the porous materials (PM) and mechanical metamaterials, specifically periodic cellular structures (PCS) or lattice cellular structure (LCS). An overview, modeling, mechanical properties, and vibration methods of each material are discussed. In this regard, thorough explanation for damping enhancement using metamaterials is provided. Besides, the paper presents separate sections to shed the light on single and 3D bandgap structures. This study also highlights the advantage of metamaterials over the porous ones, thereby showing the future of using the metamaterials as isolators. In addition, theoretical works and other aspects of metamaterials are illustrated. To this end, remarks are explained and farther studies are proposed for researchers as future investigations in the vibration field to cover the weaknesses and gaps left in the literature

Compression Behavior of Three-Dimensional Printed Polymer Lattice Structures

This paper focuses on the compression behavior of additively manufactured or three-dimensional printed polymer lattice structures of different configurations. The body-centered cubic lattice unit cell, which has been extensively investigated for energy absorption applications, is the starting point for this research. In this study, the lattice structure based on the body-centered cubic unit cell was modified by adding vertical struts in different arrangements to create three additional configurations. Four lattice structure designs were selected for comparison: the basic unit cell (body centered cubic), body centered cubic with vertical struts added to all nodes in the lattice, body centered cubic with vertical struts added to alternate nodes in the lattice, and body centered cubic with gradient in the number of vertical bars in the lattice. Samples of all four designs were prepared using acrylonitrile-butadiene-styrene polymer by three-dimensional printing. The stiffness, failure loads, and energy absorption behaviors of all four configurations were determined under quasi-static compression loading. Specific properties were calculated by normalizing the test properties by the sample mass. It is observed from experimental data that selective placement of vertical support struts in the unit cell influences both the absolute and specific mechanical properties of lattice structures

Effect of Vertical Strut Arrangements on Compression Characteristics of 3D Printed Polymer Lattice Structures: Experimental and Computational Study

This paper discusses the behavior of the three-dimensional (3D) printed polymer lattice core structures during compressive deformation, by both physical testing and computer modeling. Four lattice configurations based on the body-centered cubic (BCC) unit cell were selected to investigate the effect of vertical strut arrangements on stiffness, failure load, and energy absorption per unit mass or the specific energy absorption (SEA). The basic BCC unit cell consists of struts connecting the body center to the corners of the cube. Three variations in the BCC configuration considered in this study are (1) BCCV, with vertical members connecting all nodes of the lattice, (2) BCCA, with vertical members in alternating layers of the lattice, and (3) BCCG, with a gradient in the number of vertical members increasing from none at the top layer to all vertical members at the bottom layer. The unit cell dimensions were 5mmx5mmx5mm with strut diameter of 1mm. The lattice was assembled with 5 cells in the x and y directions and 4 cells in the z direction. Specimens were first made by 3D printing by using a fused deposition modeling printer with acrylonitrile-butadiene-styrene thermoplastic. Specimens were then tested under compression in the z direction under quasi-static conditions. Finite element analysis was used to model the compressive behavior of the different lattice structures. Results from both experiments and finite element models show that the strength of the lattice structures is greater when vertical members are present, and the SEA depends on the lattice geometry and not its mass