A Refined Lines/Regions and Lines/Lines Topological Relations Model Based on Whole-Whole Objects Intersection Components

Refined topological relations play an important role in spatial database quality control. Currently, there is no unified and reasonable method to represent refined line/region and line/line topological relations in two-dimensional (2D) space. In addition, the existing independent line/region and line/line models have some drawbacks such as incomplete type discrimination and too many topological invariants. In this paper, a refined line/region and line/line topological relations are represented uniformly by the sequence, dimension, and topological type of the intersection components. To make the relevant definitions conform to the traditional cognitions in 2D Euclidean space, the (simple) spatial object is defined based on manifold topology, and the spatial intersection components are defined based on the whole-whole object intersection set. Then the topological invariant of node degree is introduced, and the adjacent point kinds (e.g., “Null”, “On”, “In”, and “Out”) are defined to distinguish the intersection component types. Excluding impossible and symmetrical types, 29 types of intersection-lines (including 21 between lines/regions and 8 between lines/lines), and 6 types of intersection-points (including 2 between lines/regions and 4 between lines/lines) are classified. On this basis, a node degree-based whole-whole object intersection sets (N-WWIS) model for refined line/region and line/line topological relations is presented, and it can be combined with the Euler number-based whole object intersection and difference (E-WID) model (coarse level) to form a hierarchical representation method of topological relations. Furthermore, a prototype system based on the N-WWIS model for automatic topological integrity checking is developed and some evaluation experiments are conducted with OpenStreetMap (OSM) data is presented based on the classification of intersection components. The experimental results show that the N-WWIS model will enable the geographic information systems (GIS) community to develop automated topological conflict checking and dealing tools for spatial data updates and quality control.

A Smooth Transition Algorithm for Adjacent Panoramic Viewpoints Using Matched Delaunay Triangular Patches

The unnatural panoramic image transition between two adjacent viewpoints reduces the immersion and interactive experiences of 360° panoramic walkthrough systems. In this paper, a dynamic panoramic image rendering and smooth transition algorithm for adjacent viewpoints is proposed. First, the feature points of adjacent view images are extracted, a robust matching algorithm is used to establish adjacent point pairs, and the matching triangles are formed by using the homonymous points. Then, a dynamic transition model is formed by the simultaneous linear transitions of shape and texture for each control triangle. Finally, the smooth transition between adjacent viewpoints is implemented by overlaying the dynamic transition model with the 360° panoramic walkthrough scene. Experimental results show that this method has obvious advantages in visual representation with distinct visual movement. It can realize the smooth transition between two indoor panoramic stations with arbitrary station spacing, and its execution efficiency is up to 50 frames per second. It effectively enhances the interactivity and immersion of 360° panoramic walkthrough systems.

Improved high-order adjacent vertex assignment sequence for similarity vertices and isomorphism identification of planar kinematic chains

Isomorphism identification is fundamental to synthesis and innovative design of kinematic chains (KCs). The identification can be performed accurately by using the similarity of KCs. However, there are very few researches on isomorphism identification based on the properties of similarity vertices. In this paper, an improved high-order adjacent vertex assignment (IHAVS) sequence method is proposed to seek out the similarity vertices and identify the isomorphism of the planar KCs. First, the specific definition of IHAVS is described. Through the calculation of the IHAVS, the adjacent point value sequence reflecting the uniqueness of the structural features is established. Based on the value sequence, all possible similarity vertices, corresponding relations and isomorphism discrimination can be realized. By checking the topological diagrams of KCs of different number of links, the correctness of the proposed method are verified. Finally, the method is used to find the similarity vertices of all the 9-link 2-DOF(degree of freedom) planar KCs.

Conductivity Recovery Around Point Electrodes in Electrical Geo-Tomography

We consider the inverse electrical Geo-Tomography problem, where the case of piecewise constan conductivities is mostly valid under the currents injection at adjacent point electrodes and the resulting voltages measured between the remaining electrodes.The linear functional strategy from related problem in aquifer transmittivity is adapted to recover the conductivity constants in the vicinity zone containing the point electrodes. Such reconstruction method is needed as an initial step before full reconstruction of conductivity inside the domain from electrode measurements at the surface, as done in electrical GeoTomography.

Conductivity Recovery Formula Around Point Electrodes in Electrical Impedance Tomography

We consider the inverse electrical impedance problem in the case of piecewise constan conductivities with the currents injected at adjacent point electrodes and the resulting voltages measured between the remaining electrodes.Adapting the linear functional strategy from related problem in aquifer transmittivity, the conductivity can be recovered on the zone of a domain containing the point electrodes. Such reconstruction method is needed as a preliminary step before full reconstruction of conductivity inside the domain from boundary measurements, as done in electrical impedance tomography.

Binary Composite Fiber Elasticity using Spring-Mass and Non-Interacting Parallel Sub-Fiber Model

Composite materials have been investigated elsewhere. Most of the studies are based on experimental results. This paper reports a numerical study of elasticity modulus of binary fiber composite materials. In this study, we use binary fiber composite materials model which consists of materials of types A and B. The composite is simplified into compound of non-interacting parallel sub-fibers. Each sub-fiber is modeled as <em>N_s</em> point of masses in series configuration. Two adjacent point of mass is connected with spring constant <em>k</em> (related and proportional to Young modulus <em>E</em>), where it could be <em>k</em>_AA, <em>k</em>_AB, or k_BB depend on material type of the two point of masses. Three possible combinations of spring constant are investigated: (a) [<em>k</em>_AB &lt; min(<em>k</em>_AA, <em>k</em>_BB)], (b) [min(<em>k</em>_AA, <em>k</em>_BB) &lt; <em>k</em>_AB &lt; max(<em>k</em>_AA, <em>k</em>_BB)], and (c) [max(<em>k</em>_AA, <em>kBB</em>) &lt; <em>k</em>_AB]. The combinations are labeled as composite type I, II, and III, respectively. It is observed that only type II fits most the region limited by Voight and Reuss formulas.

Binary Composite Fiber Elasticity using Spring-Mass and Non-Interacting Parallel Sub-Fiber Model

Composite materials have been investigated elsewhere. Most of the studies are based on experimental results. This paper reports a numerical study of elasticity modulus of binary fiber composite materials. In this study, we use binary fiber composite materials model which consists of materials of types A and B. The composite is simplified into compound of non-interacting parallel sub-fibers. Each sub-fiber is modeled as <em>N_s</em> point of masses in series configuration. Two adjacent point of mass is connected with spring constant <em>k</em> (related and proportional to Young modulus <em>E</em>), where it could be <em>k</em>_AA, <em>k</em>_AB, or k_BB depend on material type of the two point of masses. Three possible combinations of spring constant are investigated: (a) [<em>k</em>_AB &lt; min(<em>k</em>_AA, <em>k</em>_BB)], (b) [min(<em>k</em>_AA, <em>k</em>_BB) &lt; <em>k</em>_AB &lt; max(<em>k</em>_AA, <em>k</em>_BB)], and (c) [max(<em>k</em>_AA, <em>kBB</em>) &lt; <em>k</em>_AB]. The combinations are labeled as composite type I, II, and III, respectively. It is observed that only type II fits most the region limited by Voight and Reuss formulas.