A novel approach for changing the coupling nature between TE01δ‐mode dielectric resonators

In this article, a novel coupling method which could easily change the coupling nature between two TE_01δ‐mode dielectric resonators (DRs) is presented. This method is based on electric field orientation of DR operating in TE_01δ‐mode, through altering the direction of the coupling structure in one DR, the coupled electric field orientation in the other DR would be changed along with the coupling nature between two resonators. To prove this method, two filters using cascaded quadruplet coupling structure have been designed, fabricated and measured. The coupling strength is enhanced due to the employ of two grounded mental cylinder on both sides of the copper sheet. In addition, a tuning screw is introduced between two DRs to adjust the coupling strength after mounting expediently. Measured results confirmed the predicted performance, showing that the coupling nature and coupling strength are controllable between two DRs. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:226–231, 2016.     

A Geometric Approach for the Theory and Applications of 3D Projective Invariants

A central task of computer vision is to automatically recognize objects in real-world scenes. The parameters defining image and object spaces can vary due to lighting conditions, camera calibration and viewing position. It is therefore desirable to look for geometric properties of the object which remain invariant under such changes in the observation parameters. The study of such geometric invariance is a field of active research. This paper presents the theory and computation of projective invariants formed from points and lines using the geometric algebra framework. This work shows that geometric algebra is a very elegant language for expressing projective invariants using n views. The paper compares projective invariants involving two and three cameras using simulated and real images. Illustrations of the application of such projective invariants in visual guided grasping, camera self-localization and reconstruction of shape and motion complement the experimental part.     

A 3‐D unconditionally stable precise integration time domain method for the numerical solutions of Maxwell's equations in circular cylindrical coordinates

An unconditionally stable precise integration time‐domain method is extended to 3‐D circular cylindrical coordinates to solve Maxwell's equations. In contrast with the cylindrical finite‐difference time‐domain method, not only can it remove the stability condition restraint, but also make the numerical dispersion independent of the time‐step size. Numerical results are presented to demonstrate the effectiveness of this method. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A workflow for handling heterogeneous 3D models with the TOUGH2 family of codes: Applications to numerical modeling of CO2 geological storage

This paper is addressed to the TOUGH2 user community. It presents a new tool for handling simulations run with the TOUGH2 code with specific application to CO₂ geological storage. This tool is composed of separate FORTRAN subroutines (or modules) that can be run independently, using input and output files in ASCII format for TOUGH2. These modules have been developed specifically for modeling of carbon dioxide geological storage and their use with TOUGH2 and the Equation of State module ECO2N, dedicated to CO₂-water-salt mixture systems, with TOUGHREACT, which is an adaptation of TOUGH2 with ECO2N and geochemical fluid-rock interactions, and with TOUGH2 and the EOS7C module dedicated to CO₂-CH₄ gas mixture is described. The objective is to save time for the pre-processing, execution and visualization of complex geometry for geological system representation. The workflow is rapid and user-friendly and future implementation to other TOUGH2 EOS modules for other contexts (e.g. nuclear waste disposal, geothermal production) is straightforward. Three examples are shown for validation: (i) leakage of CO₂ up through an abandoned well; (ii) 3D reactive transport modeling of CO₂ in a sandy aquifer formation in the Sleipner gas Field, (North Sea, Norway); and (iii) an estimation of enhanced gas recovery technology using CO₂ as the injected and stored gas to produce methane in the K12B Gas Field (North Sea, Denmark).     

Statistical Modeling of the 3D Geometry and Topology of Botanical Trees

We propose a framework for statistical modeling of the 3D geometry and topology of botanical trees. We treat botanical trees as points in a tree‐shape space equipped with a proper metric that captures the geometric and the topological differences between trees. Geodesics in the tree‐shape space correspond to the optimal sequence of deformations, i.e. bending, stretching, and topological changes, which align one tree onto another. In this way, the 3D tree modeling and synthesis problem becomes a problem of exploring the tree‐shape space either in a controlled fashion, using statistical regression, or randomly by sampling from probability distributions fitted to populations in the tree‐shape space. We show how to use this framework for (1) computing statistical summaries, e.g. the mean and modes of variations, of a population of botanical trees, (2) synthesizing random instances of botanical trees from probability distributions fitted to a population of botanical trees, and (3) modeling, interactively, 3D botanical trees using a simple sketching interface. The approach is fast and only requires as input 3D botanical tree models with a known upright orientation.