Geometric Similarity Measurement Method for Micro Scene Generalization

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.

Secure Clamping of Parts for Disassembly for Remanufacturing

Robot based remanufacturing of valuable products is commonly perceived as promising field in future in terms of an efficient and globally competitive economy. Additionally, it plays an important role with regard to resource-efficient manufacturing. The associated processes however, require a reliable non-destructive disassembly. For these disassembly processes, there is special robot periphery essential to enable the tasks physically. Unlike manufacturing, within remanufacturing there are End-of-Life (EoL) products utilized. The specifications and conditions are often uncertain and varying. Consequently the robot system and especially the periphery needs to adapt to the used product, based on an initial examination and classification of the part. State of the art approaches provide limited flexibility and adaptability to the disassembly of electric motors used in automotive industry. Especially the geometrical shape is a limiting factor for using state of the art periphery for remanufacturing. Within this contribution a new kind of flexible clamping device for the disassembly of EoL electrical motors is presented. The robot periphery is systematically developed regarding the requirements stemming from the remanufacturing approach. It consists of three clamping units with moveable pins. Utilizing two linear axes, a two dimensional working space is realized for clamping the parts depending on their conditions and shape.

Numerical Simulation of the Stability of Rock Mass around Large Underground Cavern

Geotechnical problems are complicated to the extent and cannot be expected in other areas since non-uniformities of existing discontinuous, pores in materials and various properties of the components. At present, it is extremely difficult to develop a program for tunnel analysis that considers all complicated factors. However, tunnel analysis has made remarkable growth for the past several years due to the development of numerical analysis method and computer development, given the situation that it was difficult to solve formula of elasticity, viscoelasticity, and plasticity for the dynamic feature of the ground when the constituent laws, yielding conditions of ground materials, geometrical shape and boundary conditions of the structure were simulated in the past. The stability of rock mass around an underground large cavern is the key to the construction of large-scale underground projects. In this paper, the stability analysis was carried out based on those parameters by using 2D FEM RS2 program. The calculated stress and displacements of surrounding rock and rock support by FEM analysis were compared with those allowable values. The pattern of deformation, stress state, and the distribution of plastic areas are analyzed. Finally, the whole stability of surrounding rock mass of underground caverns was evaluated by Rock Science - RS2 software. The calculated axial forces were far below design capacity of rock bolts. The strong rock mass strength and high horizontal to vertical stress ratio enhanced safe working conditions throughout the excavation period. Thus wide span caverns and the system of caverns could be stability excavated sedimentary rock during the underground cavern and the system of caverns excavation by blasting method. The new method provides a reliable way to analyze the stability of the caverns and the system of caverns and also will help to design or optimize the subsequent support. Doi: 10.28991/CEJ-2022-08-01-06 Full Text: PDF

3D TOPOLOGICAL SUPPORT IN SPATIAL DATABASES: AN OVERVIEW

The storage of spatial data that consists of spatial and non-spatial properties requires a database management system that possesses spatial functions that can cater to the spatial characteristics of data. These characteristics include the geometrical shape, topological and positional information. Parallel to how geometries describe the shape of an object, topological information is also an important spatial property which describes how the geometries in a space are related to each other. This information describes the connectivity, containment and adjacencies of spatial objects which are the foundation for more complex analysis such as navigation, data reconstruction, spatial queries and others. However, the topological support provided by spatial databases varies. This paper provided an overview on the current implementations of topological support in spatial databases such as ArcGIS, QGIS, PostgreSQL and others. The native topology in most spatial databases was found to be 2D topology maintained by 2D topology rules with limited representation of 3D topological relationships. Consequently, 3D objects represented by 2D topology had to be decomposed into objects of lower dimensions. Approaches to implement additional topological support for spatial databases included the use of topological data models, data structures, operators, and rules. 3D applications such as 3D cadastre required more detailed representations of topological information which required a more comprehensive 3D topological data model. Nonetheless, comprehensive preservation of topological information also mandates voluminous storage and higher computational efficiency. Thus, the appropriate 3D topological support should be provided in spatial databases to accurately represent 3D objects and meet 3D analysis requirements.

Size-Dependent Stability of a Cantilevered Piezoelectrically Actuated Micropipe Conveying Fluid

Size-dependent effects of a cantilevered piezoelectrically actuated micropipe conveying fluid are investigated. Based on the modified strain gradient beam theory, the model of system is obtained using Hamilton's principle. The motion equation is discretized into ordinary differential equations by Generalized Differential Quadrature Method (GDQM). A stability analysis of the system is completed through eigenvalue analysis. Numerical results show the effect of geometrical shape size, and length scale parameters on critical flow velocity, and critical voltage. Results prove that the modified strain gradient theory (MSGT) has a higher critical flow velocity and critical voltage than predicted by modified couple stress theory (MCST) and classical theory (CT).

The presence of irrelevant alternatives paradoxically increases confidence in perceptual decisions

Confidence in perceptual decisions often reflects the probability of being correct. Hence, we predicted that confidence should be unaffected or be minimally decreased by the presence of irrelevant alternatives. To test this prediction, we designed three experiments. In Experiment 1, participants had to identify the largest geometrical shape among two or three alternatives. In the three-alternative condition, one of the shapes was much smaller than the other two, being a clearly incorrect choice. Counter-intuitively, all else being equal, confidence was higher when the irrelevant alternative was present. We accounted for this effect with a computational model where confidence increases monotonically with the number of irrelevant alternatives, a prediction we confirmed in Experiment 2. In Experiment 3, we evaluated whether this effect replicated in a categorical task, but we did not find supporting evidence. Our findings stimulate the use of multi-alternative decision-making tasks to build a thorough understanding of confidence.

Thermo-hydraulic assessment of non-Newtonian MWCNT nanofluid flows inside microchannels with different cross-sections

In the present study, the convective heat transfer of MWCNT/water nanofluid was investigated along microchannels with different cross-sectional geometries. This class of carbon-based nanofluid exhibited a notable non-Newtonian shear-thinning behavior, which made them suitable for different heat transfer applications. A two-phase mixture model with a well-tuned non-Newtonian viscosity function was adapted. The effects of the volume fraction of nanoparticles, Reynolds number, and the geometrical shape of the cross-section were examined on the pressure drop and heat transfer rate across various microchannels. The obtained results showed that the microchannel cross-section geometry had a significant effect on the thermal performance of MWCNT/water nanofluids under certain thermal conditions. Moreover, it was deduced that for all Reynolds numbers and nanoparticle volume fractions considered, the flattened geometry exhibited the most superior thermal performance, which is around 19.03% larger than the circle geometry at Re = 1000 and volume fraction of 2%.

Effect of Geometrical Shape on Axial Deformation of Soft Actuator

Soft actuators are the latest trend of research because of their light weight and ease of manufacturing and control. Soft actuators have expanded their fields and taken place in many applications where linear or angular deflection is required. Soft actuators are very useful in the applications where deflection is required with soft touch. Soft Actuators are highly compliant and adaptive to unknown environments. Because of these characteristics, soft actuators are very popular in the field of medical and in the applications where interaction with fragile structure is required. The soft actuators can give required responses mostly depends on their shape. Linear or angular deformation can be achieved by changing the geometrical shape of actuators. This paper presents the effect of geometrical shape on axial deformation of soft pneumatic actuator. Samples of soft actuators are selected with various shapes for finite element analysis. Results are obtained in form of axial and lateral deformation. An attempt is made to achieve good amount of axial deformation with very less or negligible lateral deformation by selecting appropriate shape. Based on the generated results, the shape is identified which gives desired results and more suitable among the selected nine samples. This sample can be useful in the application having space constraint in lateral direction.

Numerical Simulation and Experimental Verification of Electric–Acoustic Conversion Property of Tangentially Polarized Thin Cylindrical Transducer

In solving piezoelectric equations of motion, we established an electric–acoustic equivalent circuit of tangentially polarized thin cylindrical transducers and derived analytical expressions of the electric-acoustic response from the harmonic driving-voltage excitation. To experimentally verify the findings, we manufactured a parallel electric-acoustic transmission network for transducers excited by multifrequency driving signals. We found that the tangentially polarized thin cylindrical transducers achieved a much higher electric-acoustic conversion efficiency than the radially polarized thin cylindrical transducers. The electric-acoustic impulse response of the transducers consisted of a direct-current damping with lower-frequency components, a damping oscillation with higher-frequency elements, and a higher resonant frequency of the transducer over its center frequency. The characteristics of radiated acoustic signals included contributions from the geometrical shape and size of the transducer, the physical parameters of piezoelectric material, the type of driving-voltage signals, and the polarization mode of the transducers. In comparison, our theoretical predictions are in good agreement with experimental observations. It is plausible that using the tangentially polarized thin cylindrical transducers as sensors in the acoustic-logging tool may significantly improve the signal-to-noise ratio of the measured acoustic-logging signals.