Facet Model Research Articles

SAR IMAGING SIMULATION FOR COMPOSITE MODEL OF SHIP ON DYNAMIC OCEAN SCENE

An e-cient double superimposition model (DSM) is proposed to generate two-dimensional (2-D) ocean surface waves. On the basis of this e-cient model, a modulated slope-deterministic facet model (MSDFM) is developed to compute the radar cross section (RCS) of synthetic aperture radar (SAR) for the generated ocean surface. Then, the properties of the SAR imaging mechanism for wind seas are discussed from a combination of SAR and ocean wave parameters. Furthermore, a hybrid facet scheme, which is the combination of physical theory of difiraction equivalent edge currents (PTDEEC) and physical optics (PO) method, is introduced to analyze the high frequency scattering characteristics of large ship target. Finally, this hybrid facet scheme combines with the four-path model and MSDFM to investigate SAR imaging for the composite model of ship on dynamic ocean scene. The resolution degradation of ship-ocean model arising from difierent facet velocities within a SAR resolution cell and the range migration caused by coupling scattering are investigated in this paper. SAR imagery simulations of marine scene are illustrated, proving the validity and practicability of the presented algorithms.

Crack surface extraction of industrial CT volume data using FPIT and planelet

As an advanced nondestructive testing (NDT) technology, industrial computed tomography (ICT) has been widely applied to diversified areas. In modern industry, ICT is especially useful for analyzing inner defects of complex and close work pieces. The common defects of work pieces include gas cavities, slag inclusions, cracks and shrinking cavities. Only cracks are often caused by fatigue usage. Precisely extracting a crack is important to estimate the remaining secure service time of the work piece. This paper presents a crack surface extraction method of ICT volume data based on finite plane integral transform (FPIT) and planelet. FPIT and planelet, as new methods of multiscale geometric analysis (MGA), have distinct discrimination for different plane singularities. Within the paper, firstly the definitions of FPIT and planelet are introduced. Secondly, after analyzing the components and relationship of planelet at monoscale, a fast performance of planelet transform is designed. Thirdly, the steps of the proposed crack surface extraction method are described. In numeric experiment, compared with the method of 3D facet model, C-V model and 3D wavelet respectively, the proposed method can extract the crack surface full and continuously, which,is robust to noise.

An Efficient Slope-Deterministic Facet Model for SAR Imagery Simulation of Marine Scene

An efficient slope-deterministic facet model for the computation of the radar scattering cross section from electrically large sea surface is presented. As a facet-based theory, it is a more comprehensive model which can adequately reflect the specular and diffuse configurations, as well as the mono- and bistatic features. Significant computational efficiency and good agreement with experimental data are observed, which make the proposed facet model well suitable for fast simulation on ocean synthetic aperture radar (SAR) imagery. Base on the facet model, a hybrid scheme is developed to analyze the high frequency composite scattering from the model of a ship at sea, in which the method of equivalent currents (MEC) and a hybrid frame which combines the four path model with the quasi-image method are employed to investigate the scattering characteristics of large ship-like target and its interactions with sea surface respectively. Finally, applications to SAR imagery simulation of marine scene are discussed with the help of the proposed sea and ship-sea scattering mechanism in detail.

Precise Vectorization of Industrial Computed Tomographic Image

Circle, line and circular arc are the common basic elements in industrial computed tomography (ICT) image. The algorithm of recognizing such elements is the key to industrial CT image precise vectorization. An industrial CT image vectorization system has been studied, including different recognition methods for these elements. Firstly, based on facet model, the sub-pixel edge of an industrial CT image is extracted. Then, the circles are recognized by an improved algorithm based on probability of existence map, while the lines are recognized with the set intersection algorithm of fitting a straight line, and the circular arcs are recognized by the combination of the perpendicular bisector tracing algorithm and least squares function. Finally, the element parameters are measured according to recognition results, and the drawing exchange file (DXF) is produced and transmitted into the computer aided design (CAD) system to be edited and consummated. The experimental results show that these methods are capable of recognizing graphic elements in industrial CT image with an excellent accuracy, besides, the absolute errors of circles are less than 0.1 mm, the relative errors are less than 0.5%. It can satisfy the industrial CT vectorization requirements of higher precision, rapid speed and non-contact.

A methodology for building a semantically annotated multi-faceted ontology for product family modelling

Product family design is one of the prevailing approaches in realizing mass customization. With the increasing number of product offerings targeted at different market segments, the issue of information management in product family design, that is related to an efficient and effective storage, sharing and timely retrieval of design information, has become more complicated and challenging. Product family modelling schema reported in the literature generally stress the component aspects of a product family and its analysis, with a limited capability to model complex inter-relations between physical components and other required information in different semantic orientations, such as manufacturing, material and marketing wise. To tackle this problem, ontology-based representation has been identified as a promising solution to redesign product platforms especially in a semantically rich environment. However, ontology development in design engineering demands a great deal of time commitment and human effort to process complex information. When a large variety of products are available, particularly in the consumer market, a more efficient method for building a product family ontology with the incorporation of multi-faceted semantic information is therefore highly desirable. In this study, we propose a methodology for building a semantically annotated multi-faceted ontology for product family modelling that is able to automatically suggest semantically-related annotations based on the design and manufacturing repository. The six steps of building such ontology: formation of product family taxonomy; extraction of entities; faceted unit generation and concept identification; facet modelling and semantic annotation; formation of a semantically annotated multi-faceted product family ontology (MFPFO); and ontology validation and evaluation are discussed in detail. Using a family of laptop computers as an illustrative example, we demonstrate how our methodology can be deployed step by step to create a semantically annotated MFPFO. Finally, we briefly discuss future research issues as well as interesting applications that can be further pursued based on the MFPFO developed.

Faceted classification for museum artefacts

PurposeThis research project aims to provide a new visual representation of the Artefacts Canada digital collection, as well as a means for users to browse this content. Artefacts Canada Humanities is a database containing approximately 3.5 million records describing the different collections of Canadian museums.Design/methodology/approachA four‐step methodology was adopted for the development of the faceted taxonomy model. First, a best practice review consisting of an extensive analysis of existing terminology standards in museum communities and public web interfaces of large cultural organizations was performed. The second step of the methodology entailed a domain analysis; this involved extracting and comparing relevant concepts from terminological authoritative sources. The third step proceeded to term clustering and entity listing,which involved the breaking‐up of the taxonomy domains into potential facets. An incremental user testing was also realized in order to validate and refine the taxonomy components (facets, values, and relationships).FindingsThe project resulted in a bilingual and expandable vocabulary structure that will further be used to describe the Artefacts Canada database records. The new taxonomy simplifies the representation of complex content by grouping objects into similar facets to classify all records of the Artefacts Canada database. The user‐friendly bilingual taxonomy provides worldwide visitors with the means to better access Canadian virtual museum collections.Originality/valueFew methodological tools are available for museums which wish to adopt a faceted approach in the development of their web sites. For practitioners, the methodology developed within this project is a direct contribution to support web site development of large cultural organizations.

Facet Model of Moving Targets for ISAR Imaging and Radar Back-Scattering Simulation

A facet model of targets is proposed to simulate inverse synthetic aperture radar (ISAR) images and radar back-scattering of moving targets with rigid and nonrigid motions. Targets are composed of solid objects which are modeled by triangular facets. It is shown that a facet can be treated as an equivalent point-scatterer whose radar cross section (RCS) and position depend on the shape of the triangle, the frequency, and the angle of incidence. A shadowing algorithm is also developed to detect the facets which actually have influence on the signal received by the radar. Besides, a facet division algorithm is implemented to improve the result of the shadowing algorithm and to have at least one facet per resolution cell. Finally, we apply our simulator to obtain the ISAR images of a ship and a helicopter and to calculate the micro-Doppler signature of a human.

EXTERNALITIES AND THE SIX FACETS MODEL OF TECHNOLOGY MANAGEMENT: GENETICALLY MODIFIED ORGANISMS IN AGRIBUSINESS

The Six Facets Model of technology management has previously only been applied to process innovation at the firm and the industry level. In this article, the model is applied to product innovation for the first time. In the context of genetically-modified organisms in the agribusiness industry, we examine radical product innovation through the Six Facets Model. We propose, based on the history of genetically-modified organisms in agribusiness, that when applied to product innovation the Six Facets Model will benefit considerably from the inclusion of potential negative externalities and the reactions of external stakeholders.

基于Facet模型的闪光图像边缘检测

基于Facet模型的闪光图像边缘检测

Feasibility of Cloud Screening Using Proxy Photon Pathlength Distributions Derived from High-Resolution Spectra in the Near Infrared

Abstract High-resolution spectra of reflected sunlight in the 2-μm absorption band of CO2 are simulated at the top of the atmosphere using cloud profiles and particle sizes from CloudSat analyzed meteorology from ECMWF, surface bidirectional distribution functions over land derived from the Moderate Resolution Imaging Spectroradiometer (MODIS), and a facet model of ocean reflectance. It is argued that in clear sky the photons will follow the direct path from sun to surface to satellite, because Rayleigh scattering is negligible at 2 μm, so the distribution of photon pathlengths will be a δ function. A proxy for the photon pathlength distribution under any sky condition is recovered from the high-resolution spectrum by representing the distribution as a weighted sum of δ functions. Scenes are classified as clear or cloudy according to how closely the distribution approximates the ideal single δ function for the direct path. The algorithm has an efficiency of approximately 75%, meaning that 25% of the clear cases will be rejected as cloudy. For scenes that pass the clear-sky test, the probability that the prediction will be correct is typically 95%. The algorithm appears to be robust, insensitive to instrument noise and to errors in the surface pressure and profiles of temperature and water vapor. The efficiency and confidence level of the algorithm are almost unchanged for bright surfaces such as sun glint.

Integrated thermal comfort analysis using a parametric manikin model for interactive real-time simulation

Following the work of Fiala (Fiala, D., Lomas, K., and Stohrer, M., 2001. Computer prediction of human thermoregulatory and temperature-responses to a wide range of environmental conditions. International Journal of Biometeorology, 45, 143–159) we developed and tested a parametric multi-segment manikin model as the interface between Fiala's human thermoregulation model and other computational codes for studying transient and local effects of thermal sensation and comfort perception. The model allows for motion control by transforming body parts according to an armature model which relates topological dependencies. The position of joints and decomposition into segments is chosen in terms of the settings of Fiala's model. Several faceted geometric models are available such as the NASA MSIS Standard or predefined NASTRAN geometries. The developed thermoregulation interface provides means to computational steering, i.e. to interact with an ongoing simulation. The boundary conditions, the type of clothing, or the activity level can be modified online, results are updated on a real time scale during the simulation. The visualization on the artificial skin of the manikin includes the surface/skin temperatures and the local thermal sensation votes (LTSV); likewise the predicted mean vote (PMV) and the dynamic thermal sensation (DTS) are output. The LTSV data are based on experimental data which were obtained in a test chamber involving 24 test subjects for three levels of clothing insulation and a light level of activity.

Polygon crawling: feature edge extraction from a general polygonal surface for mesh generation

This article describes a method for extracting feature edges of a polygonal surface for mesh generation. This method can extract feature edges from a polygonal surface typically created by a CAD facet generator in which typical feature edge extraction methods fail due to severe nonuniformity and anisotropy. The method is based on the technique called “polygon crawling,” which samples a sequence of points on the polygonal surface by moving a point along the polygonal surface. Extracting appropriate feature edges is important for creating a coarse mesh without yielding self-intersections. Extensive tests have been performed with various CAD-generated facet models, and this technique has shown good performance in extracting feature edges.

Do sex differences in a faceted model of fluid and crystallized intelligence depend on the method applied?

Abstract Recently, different methodological approaches have been discussed as an explanation for inconsistencies in studies investigating sex differences in different intelligences. The present study investigates sex differences in manifest sum scores, factor score estimates, and latent verbal, numerical, figural intelligence, as well as fluid and crystallized intelligence as measured by the German Intelligence-Structure-Test 2000-R (IST 2000-R; Liepmann, Beauducel, Brocke, & Amthauer, 2007). The not population-representative sample consisted of 977 German 11th and 12th graders enrolled in a “Gymnasium” (551 female; mean age: M = 16.70; SD = 0.65) who completed the IST 2000-R. Sex differences in fluid and crystallized intelligence were not influenced by the method applied with men performing better than women. However, extent and direction of sex differences in verbal, numerical, and figural intelligence differed by the method applied. Whereas there was a male advantage in all three factors measured as manifest sum scores, women performed better in verbal intelligence as measured by factor scores or as latent variables. Effect sizes of sex differences in numerical and figural intelligence were also greatly reduced when applying the latter two methods. Results are discussed with regard to their theoretical and practical implications.

An Assessment of Geometric Activity Features for Per-pixel Classification of Urban Man-made Objects using Very High Resolution Satellite Imagery

In this paper, the authors propose the use of Geometric Activity (GA) features for detecting man-made objects in urban areas using VHR satellite imagery. These features describe the geometric context of a pixel without the necessity of segmentation and can be integrated as extra bands in a per-pixel classification. Two main types of GA features were investigated: ridge features based on the well-known facet model and morphological features obtained by applying closing transforms with structuring elements of different size and shape. The findings show a substantial increase in classification accuracy for the man-made object classes roads and buildings with dark roof after inclusion of GA features. Next to GA features, the use of object-based features derived from eCognition®, containing both geometric and textural information, was also investigated for per-pixel classification. Accuracies obtained with object-based features are comparable to the accuracies obtained with GA features. The inclusion of both GA features and object-based features further improves the overall accuracy. GA features and object-based features thus contain complementary information.

Grain boundary mobility and grain growth behavior in polycrystals with faceted wet and dry boundaries

The effect of an intergranular amorphous film on grain growth behavior has been studied in a faceted model system, BaTiO 3. We prepared two kinds of samples with and without intergranular amorphous films but with the same grain size and density. During annealing the samples at 1350 °C in air, abnormal grain growth occurred in samples with intergranular amorphous films while grain growth was inhibited in samples with dry boundaries, indicating the presence of a pinning force in samples with dry boundaries. To compare the mobilities of dry and wet boundaries, single crystal and polycrystal bilayer samples with or without amorphous films were prepared and annealed at 1340 °C. In contrast to the observed grain growth behavior in polycrystals, the growth of the single crystal into the polycrystal with dry boundaries was faster than that into the polycrystal with wet boundaries, demonstrating the higher mobility of a dry boundary, unlike the conventional understanding.

Application of RTDF to particles with curved surfaces

The applicability of the ray tracing with diffraction on facets model is extended to particles with curved surfaces. This allows tests against T-matrix calculations for larger size parameters and modelling of light scattering by more realistic particle shapes, such as ice crystals with rounded edges.

Development of an occupant model for far-side vehicle crashes

The biofidelity and performance requirements for a far-side occupant model are described. Previous work is analysed that highlights the potential use of a modified version of the TNO Human Facet Model for simulating far-side impacts. The model's biofidelity and performance are compared with PMHS results from pelvic offset sled tests, pendulum tests and a full-scale far-side crash test. Results indicate that the model exhibits good biofidelity compared with PMHS results, specifically its ability to simulate: belt interaction with the shoulder; loading to the pelvis, thorax and abdomen and whole body kinematics in a full-vehicle far-side crash. The model's main limitations are that its thorax is less capable of matching the magnitude of deflection observed in the PMHS pendulum tests.

ROBUST SEMI-DETERMINISTIC FACET MODEL FOR FAST ESTIMATION ON EM SCATTERING FROM OCEAN-LIKE SURFACE

A robust semi-deterministic facet model for the computa- tion of the radar scattering cross section from the ocean-like surface is presented. As a facet-based theory, it is a more comprehensive model which can re∞ect the specular and difiuse conflgurations, as well as the mono- and bistatic features. Signiflcant computational e-ciency and good agreement with experimental data are observed, which makes the proposed facet model well suitable for fast estimation on EM scatter- ing and synthetic aperture radar (SAR) imagery simulation of marine scene.

3D Surface Reconstruction and Analysis in Automated Apple Stem-End/Calyx Identification

Machine vision methods are widely used in apple defect detection and quality grading applications. Currently, 2D near-infrared (NIR) imaging technology is used to detect apple defects based on the difference in image intensity of defects from normal apple tissue. However, it is difficult to accurately differentiate an apple's stem-end/calyx from a true defect due to their similar 2D NIR images, which presents a major technical challenge to the successful application of this machine vision technology. In this research, we used a novel two-step 3D data analysis strategy to differentiate apple stem-ends/calyxes from true defects according to their different 3D shape information. In the first step, a 2D NIR imaging was extended to a 3D reconstruction using a shape-from-shading (SFS) approach. After successfully obtaining 3D information, a quadratic facet model was introduced to conduct the 3D concave shape fitting such that the identification of apple stem-ends and calyxes could be achieved based on their different 3D structures. Significant improvement in terms of the detection rate could be obtained based on 3D shape fitting in comparison to the traditional 2D intensity fitting approach. Samples of the reconstructed 3D apple surface maps as well as the identified stem-ends/calyxes were shown in the results, and an overall 90.15% detection rate was achieved, compared to the 58.62% detection rate of the traditional 2D intensity fitting approach.

Fast Shadowing Technique for Electrically Large Targets Using Z-Buffer

An improved fast shadowing technique fit for the calculation of electromagnetic field is proposed in this paper based on the shadowing technique of z-buffer in computer graphics. The traditional shadowing algorithm consumes too much time, for it is necessary to judge the shadowing relationship of every two facets. The proposed algorithm combining z-buffer with traditional algorithm falls into the shadowing processing using triangle facet modeling. The problem of great time consumption in shadowing judgment for electrically large targets is well solved through proper subdivision of buffer and localization of judgment within facets in the surrounding buffer elements. The proposed arithmetic has great advantages over the traditional one, especially in its high running speed. This improved technique is tested to be valid in that it remarkably increases the computation speed on the premise of satisfying the precision requirement.