scholarly journals Segmentation of Change in Surface Geometry Analysis for Cultural Heritage Applications

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4899
Author(s):  
Sunita Saha ◽  
Jacek Martusewicz ◽  
Noëlle L. W. Streeton ◽  
Robert Sitnik
Keyword(s):  
Cultural Heritage ◽  
Target Surface ◽  
Segmentation Method ◽  
Surface Geometry ◽  
Time Intervals ◽  
Measurement Results ◽  
Local Distance ◽  
Geometrical Data ◽  
Point To Point ◽  
Geometry Analysis

This work proposes a change-based segmentation method for applications to cultural heritage (CH) imaging to perform monitoring and assess changes at each surface point. It can be used as a support or component of the 3D sensors to analyze surface geometry changes. In this research, we proposed a new method to identify surface changes employing segmentation based on 3D geometrical data acquired at different time intervals. The geometrical comparison was performed by calculating point-to-point Euclidean distances for each pair of surface points between the target and source geometry models. Four other methods for local distance measurement were proposed and tested. In the segmentation method, we analyze the local histograms of the distances between the measuring points of the source and target models. Then the parameters of these histograms are determined, and predefined classes are assigned to target surface points. The proposed methodology was evaluated by considering two different case studies of restoration issues on CH surfaces and monitoring them over time. The results were presented with a colormap visualization for each category of the detected change in the analysis. The proposed segmentation method will help in the field of conservation and restoration for the documentation and quantification of geometrical surface change information. This analysis can help in decision-making for the assessment of damage and potential prevention of further damage, and the interpretation of measurement results.

Geometrical characterisation of fault arrays in three dimensions

2021 ◽  
Author(s):  
Vincent Roche ◽  
Giovanni Camanni ◽  
Conrad Childs ◽  
Tom Manzocchi ◽  
John Walsh ◽  
...  
Keyword(s):  
Full Range ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Normal Faults ◽  
Fault Geometry ◽  
Surface Geometry ◽  
Fault Surface ◽  
Mechanical Stratigraphy ◽  
Quantitative Basis ◽  
Geometry Analysis

<p>Normal faults are often complex three-dimensional structures comprising multiple sub-parallel segments separated by intact or breached relay zones. In this study we outline geometrical characterisations capturing this 3D complexity and providing a semi-quantitative basis for the comparison of faults and for defining the factors controlling their geometrical evolution. Relay zones are classified according to whether they step in the strike or dip direction and whether the relay zone-bounding fault segments are unconnected in 3D or bifurcate from a single surface. Complex fault surface geometry is then described in terms of the relative numbers of different types of relay zones to allow comparison of fault geometry between different faults and different geological settings. A large database of 87 fault arrays compiled primarily from mapping 3D seismic reflection surveys and classified according to this scheme, reveals the diversity of 3D fault geometry. Analysis demonstrates that mapped fault geometries depend on geological controls, primarily the heterogeneity of the faulted sequence and the presence of a pre-existing structure. For example, relay zones with an upward bifurcating geometry are prevalent in faults that reactivate deeper structures, whereas the formation of laterally bifurcating relays is promoted by heterogeneous mechanical stratigraphy. In addition, mapped segmentation depends on resolution limits and biases in fault mapping from seismic data. In particular, the results suggest that the proportion of bifurcating relay zones increases as data resolution increases. Overall, where a significant number of relay zones are mapped on a single fault, a wide variety of relay zone geometries occurs, demonstrating that individual faults can comprise segments that are both bifurcating and unconnected in three dimensions. Models for the geometrical evolution of fault arrays must therefore account for the full range of relay zone geometries that appears to be a characteristic of all faults.</p>

scholarly journals X-Band High-Efficiency Continuous Class B Power Amplifier GaN MMIC Assisted by Input Second-Harmonic Tuning

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1312 ◽  
Author(s):  
Chen Jin ◽  
Yuan Gao ◽  
Wei Chen ◽  
Jianhua Huang ◽  
Zhiyu Wang ◽  
...  
Keyword(s):  
Power Amplifier ◽  
Integrated Circuit ◽  
High Efficiency ◽  
Second Harmonic ◽  
Power Added Efficiency ◽  
Optimum Load ◽  
Measurement Results ◽  
Class B ◽  
Point To Point ◽  
Output Capacitance

This paper presents a high-efficiency continuous class B power amplifier MMIC (Monolithic Microwave Integrated Circuit) from 8 GHz to 10.5 GHz, fabricated with 0.25 μm GaN-on-SiC technology. The Pedro load-line method was performed to calculate the optimum load of the GaN field-effect transistor (FET) for efficiency enhancement. Optimized by an output second-harmonic tuned network, fundamental to second-harmonic impedance, mapping was established point-to-point within a broad frequency band, which approached the classic continuous class B mode with an expanded high-efficiency bandwidth. Moreover, the contribution to the output capacitance of the FET was introduced into the output second-harmonic tuned network, which simplified the structure of the output matching network. Assisted by the second-harmonic source-pull technique, the input second-harmonic tuned network was optimized to improve the efficiency of the power amplifier over the operation band. The measurement results showed 51–59% PAE (Power Added Efficiency) and 19.8–21.2 dB power gain with a saturated power of 40.8–42.2 dBm from 8 GHz to 10.5 GHz. The size of the chip was 3.2 × 2.4 mm2.

PROPERTIES OF WC-Cu ELECTRO SPARK COATINGS SUBJECTED TO LASER MODIFICATION

Tribologia ◽  
2017 ◽  
pp. 73-79 ◽  
Author(s):  
Izabela PLISZKA ◽  
Norbert RADEK ◽  
Aneta GĄDEK-MOSZCZAK
Keyword(s):  
Laser Treatment ◽  
Thin Layers ◽  
Laser Beams ◽  
Surface Geometry ◽  
Tribological Test ◽  
Electrospark Deposition ◽  
Electrospark Coating ◽  
Laser Surface Modification ◽  
Deposition Surface ◽  
Geometry Analysis

The article presents the possibilities of using laser surface modification on the way EDM to better tribological properties. The paper tries to expand knowledge in the fields of the application of electrospark deposition. Surface treatment by applying a coating by electrospark deposition has many advantages (e.g., local interface or applying thin layers); therefore, this technology is used in the industry. Concentrated streams of laser beams can effectively modified the state of the electrospark coating, WC-Cu, and improve its performance. The aim of the study is to evaluate the influence of laser treatment on the properties of electrospark coatings. Evaluation of the properties of the coatings after laser treatment was carried out by observation of the microstructure, surface geometry analysis, and tribological test.

scholarly journals ESTIMATION OF TOPOGRAPHIC DEFECTS DIMENSIONS OF SEMICONDUCTOR SILICON STRUCTURES

2018 ◽  
Vol 9 (1) ◽  
pp. 74-84
Author(s):  
S. F. Sianko ◽  
V. A. Zelenin
Keyword(s):  
Calculation Method ◽  
Target Surface ◽  
Curvature Radius ◽  
Surface Geometry ◽  
Semiconductor Wafer ◽  
Semiconductor Silicon ◽  
Quantitative Characteristics ◽  
Silicon Structures ◽  
Analytical Expressions ◽  
Acceptability Criteria

The effect of non-flatness of semiconductor wafers on characteristics of manufactured devices is shown through defocusing of an image of a topological layout of a structure being formed and through reduction of resolution at photolithographic processing. For quality control of non-flatness the Makyoh method is widely used. However, it does not allow obtaining quantitative characteristics of observed defects, which essentially restricts its application. The objective of this work has been developing of a calculation method for dimensions of topographic defects of wafers having semiconductor structures formed on them, which has allowed determining acceptability criteria for wafers, depending on defects dimensions and conducting their timely penalization.A calculation method under development is based on deduction of relationships linking distortion of image elements to curvature of local sections of a semiconductor wafer that has formed structures. These structures have been considered to be image finite elements and within this range the curvature radius has been assumed to be constant. Sequential calculation of deviation of element ends from ideal plane based on determining their curvature radius has allowed obtaining geometry of a target surface in a set range of elements. Conditions of image formation and requirements to structures have been determined.Analytical expressions relating a deviation value of elements of a light-to-dark image with surface geometry have been obtained. This allows conducting effective quantitative control of observed topographic defects both under production and research conditions. Examples of calculation of topographic defects of semiconductor silicon wafers have been provided. Comparison of the obtained results with the data obtained by conventional methods has shown their complete conformity.

Structure Deformation Measurement with Terrestrial Laser Scanner at Pathein Bridge in Myanmar

2018 ◽  
Vol 13 (1) ◽  
pp. 40-49 ◽  
Author(s):  
Nuntikorn Kitratporn ◽  
◽  
Wataru Takeuchi ◽  
Koji Matsumoto ◽  
Kohei Nagai
Keyword(s):  
Point Cloud ◽  
Cloud Model ◽  
Laser Scanner ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Terrestrial Laser Scanner ◽  
Bridge Structure ◽  
Surface Geometry ◽  
Deformation State ◽  
Measurement Results

In Myanmar, defects and possible deformation were reported in many long-span suspension bridges. The current state of bridge infrastructure must be inspected, so that deterioration can be stalled and failure can be prevented. A 3D laser scanner, specifically the terrestrial laser scanner (TLS), has demonstrated the ability to capture surface geometry with millimeter accuracy. Consequently, TLS technology has received significant interest in various applications including in the field of structural survey. However, research on its application in large bridge structure remains limited. This study examines the use of TLS point cloud for the measurement of three deformation behaviors at the Pathein Suspension Bridge in Myanmar. These behaviors include tower inclination, hanger inclination, and deflection of bridge truss. The measurement results clearly captured the deformation state of the bridge. A comparison of the measurement results with available conventional measurements yielded overall agreement. However, errors were observed in some areas, which could be due to noise and occlusion in the point cloud model. In this study, the advantages of TLS in providing non-discrete data, direct measurement in meaningful unit, and access to difficult-to-access sections, such as top of towers or main cables, were demonstrated. The limitations of TLS as observed in this study were mainly influenced by external factors during field survey. Hence, it was suggested that further study on appropriate TLS surveying practice for large bridge structure should be conducted.

scholarly journals Cultural Heritage Restoration of a Hemispherical Vault by 3D Modelling and Projection of Video Images with Unknown Parameters and from Unknown Locations

2021 ◽  
Vol 11 (12) ◽  
pp. 5323
Author(s):  
Jose Herraez ◽  
Jose L. Denia ◽  
Enrique Priego ◽  
Pablo Navarro ◽  
Maria T. Martin ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Cultural Heritage ◽  
3D Modelling ◽  
3D Image ◽  
Surface Geometry ◽  
Unknown Parameters ◽  
Mathematical Development ◽  
Video Images ◽  
Virtual Images ◽  
Architectural Restoration

Reverse engineering applied to architectural restoration for the reconstruction of structural surfaces depends on metric precision. Sometimes there are elements on these surfaces whose value is even higher than the building itself. This is the case for many churches whose ceilings have pictorial works of art. Reconstruction requires the existence of some identifiable remainder and/or a surface geometry that enables mathematical development. In our case, the vault has an irregular hemispherical geometry (without possible mathematical development), and there are no significant remains of the painting (which was destroyed by a fire). Through the 3D modelling of the irregular vault and two historic frames with a camera of unknown geometry, an inverse methodology is designed to project the original painting without metric deformations. For this, a new methodology to locate the camera positions is developed. After, a 3D virtual mathematical model of the complete image on the vault is calculated, and from it, partial 3D virtual images are automatically calculated depending on the variable unknown positions of the video cannons (distributed along the upper corridor of the apse) that will project them (visually forming a perfect complete 3D image).

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