scholarly journals Geometric Similarity Measurement Method for Micro Scene Generalization

2022 ◽  
Vol 12 (2) ◽  
pp. 628
Author(s):  
Fei Yang ◽  
Zhonghui Wang ◽  
Haowen Yan ◽  
Xiaomin Lu

Geometric similarity plays an important role in geographic information retrieval, map matching, and data updating. Many approaches have been developed to calculate the similarity between simple features. However, complex group objects are common in map and spatial database systems. With a micro scene that contains different types of geographic features, calculating similarity is difficult. In addition, few studies have paid attention to the changes in a scene’s geometric similarity in the process of generalization. In this study, we developed a method for measuring the geometric similarity of micro scene generalization based on shape, direction, and position. We calculated shape similarity using the hybrid feature description, and we constructed a direction Voronoi diagram and a position graph to measure the direction similarity and position similarity. The experiments involved similarity calculation and quality evaluation to verify the usability and effectiveness of the proposed method. The experiments showed that this approach can be used to effectively measure the geometric similarity between micro scenes. Moreover, the proposed method accounts for the relationships amongst the geometrical shape, direction, and position of micro scenes during cartographic generalization. The simplification operation leads to obvious changes in position similarity, whereas delete and merge operations lead to changes in direction and position similarity. In the process of generalization, the river + islands scene changed mainly in shape and position, the similarity change in river + lakes occurred due to the direction and location, and the direction similarity of rivers + buildings and roads + buildings changed little.

2014 ◽  
Vol 13 (9) ◽  
pp. 4859-4867
Author(s):  
Khaled Saleh Maabreh

Distributed database management systems manage a huge amount of data as well as large and increasingly growing number of users through different types of queries. Therefore, efficient methods for accessing these data volumes will be required to provide a high and an acceptable level of system performance.  Data in these systems are varying in terms of types from texts to images, audios and videos that must be available through an optimized level of replication. Distributed database systems have many parameters like data distribution degree, operation mode and the number of sites and replication. These parameters have played a major role in any performance evaluation study. This paper investigates the main parameters that may affect the system performance, which may help with configuring the distributed database system for enhancing the overall system performance.


2020 ◽  
Vol 17 (1) ◽  
pp. 0099
Author(s):  
Lekaa khalid Karem

This search includes the preparation of Schiff base ligand (SB) from condensation primary amine with vanillin. The new ligand was diagnosed by spectroscopic methods as Mass, NMR, CHN and FTIR. Ligand complexes were mixed from new (SB) and Anthranillic acid (A) with five metal (II) chlorides. The preparation and diagnosis were conducted by FTIR, CHN, UV-visible, molar conductivity, atomic absorption and magnetic moment. The octahedral geometrical shape of the complexes was proposed. The ligands and their new complexes were screened with two different types of bacteria.


Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6400
Author(s):  
Chizhao Yang ◽  
Jared Strader ◽  
Yu Gu

Localization based on scalar field map matching (e.g., using gravity anomaly, magnetic anomaly, topographics, or olfaction maps) is a potential solution for navigating in Global Navigation Satellite System (GNSS)-denied environments. In this paper, a scalable framework is presented for cooperatively localizing a group of agents based on map matching given a prior map modeling the scalar field. In order to satisfy the communication constraints, each agent in the group is assigned to different subgroups. A locally centralized cooperative localization method is performed in each subgroup to estimate the poses and covariances of all agents inside the subgroup. Each agent in the group, at the same time, could belong to multiple subgroups, which means multiple pose and covariance estimates from different subgroups exist for each agent. The improved pose estimate for each agent at each time step is then solved through an information fusion algorithm. The proposed algorithm is evaluated with two different types of scalar field based simulations. The simulation results show that the proposed algorithm is able to deal with large group sizes (e.g., 128 agents), achieve 10-m level localization performance with 180 km traveling distance, while under restrictive communication constraints.


Author(s):  
R. Autrata

There are two reasons for designing special geometrical configurations of detectors of signal electrons in EM.1. For some traditional shapes of scintillators (discs) the quantum efficiency of single crystal YAG or YAP scintillators amounting to 5% - 7% is not fully utilized for achieving the maximum light output signal propagated in the desired. The reason is the small critical angle given by the high index of refraction of both single crystal materials. The shaping of single crystal scintillators and treating of surfaces by making use of the laws of geometrical optics lead to an increase of the value of the light output signal propagated in the desired direction.2. Different kinds of information carried by signal electrons (especially BSEs) of different types must be collected by a detector of a specific geometrical shape placed in a suitable position with regard to the specimen.Non-traditional geometrical configurations and optical modifications of detectors have been designed to solve the problem of a more efficient propagation of light towards the photocathode of PMT, considering different types of signal electrons.


2020 ◽  
Vol 10 (17) ◽  
pp. 6080 ◽  
Author(s):  
Yuyang Liu ◽  
Hongpeng Lai

The water immersion of surrounding rock slide surface causes lining cracking of the shallow buried loess tunnel, and different types of slide surface and different immersion degrees have different effects on secondary lining. In this paper, four types of slide surfaces for shallow buried loess tunnel are proposed. In order to find out the characteristics and laws of lining cracking under the effect of slide surface immersion, a loading model test with a large geometric similarity ratio of 1:10 was carried out. The test results show that the immersion of the slide surface has the most significant influence on the deformation of the lining vault and the arch waist, and the value and speed of the vault deformation are always the largest. When the unilateral slide surface is immersed in water, the lining cracking is concentrated on the flooded side of the slide surface, and the appearance of compressive cracks can be regarded as a precursor of lining instability. In the direction of lining thickness, the cracks always begin to develop from I-type, then gradually develop into L-type, and finally develop to Y-type, among which the number of L-type cracks is the most. Furthermore, the residual bearing capacity of cracked lining is also discussed.


In this paper, we study about the different types of fault tolerance techniques which are used in various distributed database systems. The main focus of this research is about how the data are storedin the servers, fault detection techniques and the recovery techniques used. A fault can occur for many reasons. For example, system failure, resource failure, network between the server’s failure and any other reasons. These faults must be emphasis in order to make sure the system can work smoothly without any problem. A proper failure detector and a reliable fault tolerance technique can avoid loss and at once save the system from fail.


2004 ◽  
Vol 19 (3) ◽  
pp. 235-274 ◽  
Author(s):  
NIKOS PELEKIS ◽  
BABIS THEODOULIDIS ◽  
IOANNIS KOPANAKIS ◽  
YANNIS THEODORIDIS

Recent efforts in spatial and temporal data models and database systems have attempted to achieve an appropriate kind of interaction between the two areas. This paper reviews the different types of spatio-temporal data models that have been proposed in the literature as well as new theories and concepts that have emerged. It provides an overview of previous achievements within the domain and critically evaluates the various approaches through the use of a case study and the construction of a comparison framework. This comparative review is followed by a comprehensive description of the new lines of research that emanate from the latest efforts inside the spatio-temporal research community.


1986 ◽  
Vol 23 (04) ◽  
pp. 851-858 ◽  
Author(s):  
P. J. Brockwell

The Laplace transform of the extinction time is determined for a general birth and death process with arbitrary catastrophe rate and catastrophe size distribution. It is assumed only that the birth rates satisfyλ0= 0,λj> 0 for eachj> 0, and. Necessary and sufficient conditions for certain extinction of the population are derived. The results are applied to the linear birth and death process (λj=jλ, µj=jμ) with catastrophes of several different types.


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