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Spherical Surface (spherical + surface)
Selected AbstractsInside Front Cover: Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid Membrane (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Mater. In their Full Paper on page 201, Donald Martin and co-workers describe the covering of polyelectrolyte microcapsules with a lipid bilayer that incorporates a novel engineered ion channel to provide a functional capability to control transport across the microcapsule wall. The cover image shows atomic-force microscopy images of these 8-layer polyelectroctrolyte capsules recorded using tapping mode in an aqueous environment. The capsules can be seen to collapse in a folded manner, with an occasional wrinkle that "absorbs" the extra surface area when flattening the spherical surface. [source] Semi-Lagrangian advection on a spherical geodesic gridINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2007Maria Francesca Carfora Abstract A simple and efficient numerical method for solving the advection equation on the spherical surface is presented. To overcome the well-known ,pole problem' related to the polar singularity of spherical coordinates, the space discretization is performed on a geodesic grid derived by a uniform triangulation of the sphere; the time discretization uses a semi-Lagrangian approach. These two choices, efficiently combined in a substepping procedure, allow us to easily determine the departure points of the characteristic lines, avoiding any computationally expensive tree-search. Moreover, suitable interpolation procedures on such geodesic grid are presented and compared. The performance of the method in terms of accuracy and efficiency is assessed on two standard test cases: solid-body rotation and a deformation flow. Copyright © 2007 John Wiley & Sons, Ltd. [source] A fast spherical inflation method of the cerebral cortex by deformation of a simplex mesh on the polar coordinatesINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 1 2008Min Jeong Kwon Abstract The convoluted shape of the cerebral cortex makes it difficult to analyze and visualize the neuronal activation area. One way of overcoming this problem is to use a spherical inflation method to draw a cerebral cortex on a spherical surface. The task of mapping the cortical surface on a sphere has several obstacles, namely, the overlap between the polygons of the surface, the heavy computation demand, and the geometric distortions inherent in the process. This article proposes a method of mapping the three-dimensional (3D) cortical surface represented in a simplex mesh to a sphere surface, which does not have any overlap between the polygons and minimizes the geometric distortions as well as the computation time. The proposed method consists of the two steps of preprocessing and refinement. In the preprocessing step, the 3D cortical surface is mapped onto a sphere without any overlap between the polygons by iterative deformation. In the refinement step, the mapped surface is adjusted to minimize its linear distortion. The experimental results show the efficiency and performance of the proposed mapping method. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 18, 9,16, 2008 [source] Type synthesis of 5-DOF parallel manipulators based on screw theoryJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2005Xianwen Kong With the introduction of virtual chains to represent the motion patterns of 5-DOF motions, a classification of 5-DOF PMs (parallel manipulators) is proposed at first. A general method for the type synthesis of 5-DOF PMs is then proposed based on screw theory and using the concept of virtual chains. The type synthesis of US-equivalent PMs is presented in detail to show the application of the proposed approach. US-equivalent PMs are the parallel counterparts of the 5-DOF US serial manipulators. For a US-equivalent PM, the moving platform can rotate arbitrarily about a point moving along a spherical surface. The type synthesis of legs for US-equivalent PKCs (parallel kinematic chains), the type synthesis of US-equivalent PKCs, as well as the selection of actuated joints of US-equivalent PMs are dealt with in sequence. US-equivalent PKCs with and without inactive joints are synthesized. Several US-equivalent PMs as well as other classes of 5-DOF PMs with identical type of legs are obtained. © 2005 Wiley Periodicals, Inc. [source] Stressed Triangular Tessellations and Fibonacci Parastichous Spirals on Ag Core/SiO2 Shell MicrostructuresADVANCED MATERIALS, Issue 45 2009Chao-Rong Li Abstract Triangular tessellations and Fibonacci parastichous spirals were assembled via thermal stress engineering of Ag-core/SiO2 -shell microstructures, for which the geometry and topology of the primary core/shells play a pivotal role. Patterns on slightly stressed spherical surfaces are simply triangular tessellations with 12 pentamers, whereas additional pentamer,heptamer chains emerge when more vertices are available (>360) on heavily stressed surfaces, all showing an excellent agreement with numerical solutions to the Thomson's problem. Defect-free triangular lattice can be produced on a pierced spherical cap prepared via the draining effect. Remarkably, Fibonacci spirals of definite chirality, 3 by 5 through 13 by 21, and in both sinister and dexter forms, emerge on the conical supports. These results provide strong confirmation of the mechanical principle for phyllotaxis that the phyllotatic patterns are the least-elastic-energy configuration in a confining receptacle, and meanwhile demonstrate an effective path for the en masse fabrication of patterned structures on curved surfaces. [source] Selectivity for patch-distributed reactive spherical surfacesAICHE JOURNAL, Issue 2 2007Jui-Chuang Wu Abstract The selectivity of reactions on active patches over those on a partially active carrier surface is investigated for patch-covered spheres. The effects of relevant parameters including patch and carrier reactivities, patch coverage, patch size, and patch separation state are studied. The selectivity is found to increase with increasing relative dominance of the patch reactivity over the carrier reactivity and patch coverage, as expected. Interestingly, it also increases with decreasing patch size and increasing patch separations. Decrease in patch size creates more patch,carrier interfaces and thus enhances the competition effectiveness of the patches against the carrier surface. With respect to the patch separation state, more complete utilization of the patches is achieved for well-separated patches and thus enhances the selectivity toward the patches. © 2007 American Institute of Chemical Engineers AIChE J 2007 [source] Microtribological behaviour of thin DLC films using different testing methodsLUBRICATION SCIENCE, Issue 2 2006R. Bandorf Abstract To enhance the lifetime and reliability of microcomponents, thin microtribological films are applied to microparts. With reduction of the component size, investigation methods for tribological testing must be adapted. This paper studies the microtribological behaviour of thin diamond-like carbon (DLC) films using different testing methods. To tie in with macroscopic results, to determine friction we used the well-known pin-on-disc test with spherical surfaces of 10,mm diameter under a typical load of 3,N. For investigations of the behaviour under single asperity contact, Atomic Force Microscope (AFM) methods with applied loads of a few hundred micronewtons were used. Investigations on thin DLC films showed that the friction coefficient under single asperity contact is strongly dependent on the applied load and the resulting contact area. Especially for thin films (up to a few hundred nanometres) the friction coefficient is influenced by the substrate material. With decreasing substrate Young's modulus the friction coefficient also decreases. On the other hand, an increase in the abrasive wear resistance was observed using soft substrate materials. In this paper we show that the friction coefficient was also reduced by a simple surface structure. For investigations we used photolithography to create concentric circles in different substrates. This resulted in a behaviour like riding on rails for the pin-on-disc test. Depending on the tribological pairing the friction coefficient was reduced to more than 50% of the original value. Copyright © 2006 John Wiley & Sons, Ltd. [source] | |||||||||||||