Analysis Of Geometrical Features Research Articles

A Profile Curve Fitting Method for Automatic Dam Extraction Based on LiDAR Points Data

In this paper, an automatic dam extraction algorithm which is called polynomial curve fitting is proposed. This method is based on the LiDAR points cloud filtering and the spatial geometric distribution feature analysis. The key ideology lies in the following steps: firstly, obtain reference vectors from water profile (airborne LiDAR)or vehicle trajectory file (mobile LiDAR); secondly, a section with certain width is made along the direction of dam and the current points in that section are projected to the two-dimensional space which is vertical to the direction of the dam; then, divide the projected points along the horizontal axis into several segments andsearch a partial lowest point in every small segment, after which the polynomial coefficients of two-dimensional can be solved with least square method; lastly, calculate the distance between the point in dam section and the fitting curve, the current point can be judged as dam point when that distance to the curve is smaller than the given threshold, otherwise is not. The experiment with the vehicle LiDAR data of JingJiang Dam shows that this method can effectively extract dam point and the accuracy can be better than 0.16 m.

Automatic Hand Measurement System from 2D Hand Image for Customized Glove Production

Recent advancements in optics technology enable us to realize fast scans of hands using two-dimensional (2D) image scanners. In this paper, we propose an automatic hand measurement system using 2D image scanners for customized glove production. To develop the automatic hand measurement system, firstly hand scanning devices has been constructed. The devices are designed to block external lights and have user interface to guide hand posture during scanning. After hands are scanned, hand contour is extracted using binary image processing, noise elimination and outline tracing. And then, 19 hand landmarks are automatically detected using an automatic hand landmark detection algorithm based on geometric feature analysis. Then, automatic hand measurement program is executed based on the automatically extracted landmarks and measurement algorithms. The automatic hand measurement algorithms have been developed for 18 hand measurements required for custom-made glove pattern making. The program has been coded using the C++ programming language. We have implemented experiments to demonstrate the validity of the system using 11 subjects (8 males, 3 females) by comparing automatic 2D scan measurements with manual measurements. The result shows that the automatic 2D scan measurements are acceptable in the customized glove making industry. Our evaluation results confirm its effectiveness and robustness.

A novel reconstruction method based on changes in phase for subsurface large sloped dielectric target using GPR

In ground-penetrating radar (GPR) subsurface target reconstruction, various techniques based on amplitude (or energy) information of echoes from metal target with small size can work well. However, for environmental and geological applications, the quantitative analysis of the target's geometric features, like location, shape and size, is exactly what we are concerned about. Amplitude-based reconstruction method faces challenges in these applications. A large sloped target under the surface may lead to abundant virtual image energy and cause position deviation. In addition, the echoes from the inner part of the penetrable dielectric target may be too weak to be detected. However, changes in phase may highlight the effects of echoes from the target on that from the surroundings, even if the effect is small due to the weak energy. In this paper, a novel method based on changes in phase is proposed to reconstruct subsurface large sloped dielectric target. To remove the virtual image, the main idea is based on the geometric relationship between the recorded signal plotted beneath the receiving antenna and the reflected signal emanated from the target position which is “ahead” or “behind” of the receiving antenna. Furthermore, the electromagnetic (EM) wave propagating through the penetrable target will change its velocity and result in advancing or lagging related to the geometric shape of the target. In this case, the weak echoes from the back surface of the target can be compensated according to the advancing or lagging. With the proposed method, the virtual image is eliminated and both front and back surface of the target are reconstructed. Results from the laboratory experiments demonstrate the validity of the proposed method.

Generation of super-size macroparticles in a direct current vacuum arc discharge from a Mo-Cu cathode

An inherent property of cathodic arc is the generation of macroparticles, of a typical size ranging from submicrometer up to a few tens of μm. In this work, we have studied macroparticle generation from a Mo0.78Cu0.22 cathode used in a dc vacuum arc discharge, and we present evidence for super-size macroparticles of up to 0.7 mm in diameter. All analyzed particles are found to be rich in Mo (≥98 at. %). The particle generation is studied by visual observation of the cathode surface during arcing, by analysis of composition and geometrical features of the used cathode surface, and by examination of the generated macroparticles with respect to shape and composition. A mechanism for super-size macroparticle generation is suggested based on observed segregated layers of Mo and Cu identified in the topmost part of the cathode surface, likely due to the discrepancy in melting and evaporation temperatures of Mo and Cu. The results are of importance for increasing the fundamental understanding of macroparticle ge...

Variational Analysis for CNC Milling Process

Dimensional and geometrical defects severely affect the quality of chip removal processes in CNC machines. In order to improve the accuracy, a long and expensive calibration process is usually performed on the CNC machine. The tuning process could be easier and faster if the designer is able to evaluate the effect of error sources providing a more robust and reliable CNC machine. The joined use of variational analysis and finite element analysis of geometrical features forecasts the position error of the tool tip.

Quantifying conformational changes in GPCRs: glimpse of a common functional mechanism.

BackgroundG-protein-coupled receptors (GPCRs) are important drug targets and a better understanding of their molecular mechanisms would be desirable. The crystallization rate of GPCRs has accelerated in recent years as techniques have become more sophisticated, particularly with respect to Class A GPCRs interacting with G-proteins. These developments have made it possible for a quantitative analysis of GPCR geometrical features and binding-site conformations, including a statistical comparison between Class A GPCRs in active (agonist-bound) and inactive (antagonist-bound) states.ResultsHere we implement algorithms for the analysis of interhelical angles, distances, interactions and binding-site volumes in the transmembrane domains of 25 Class A GPCRs (7 active and 18 inactive). Two interhelical angles change in a statistically significant way between average inactive and active states: TM3-TM6 (by -9°) and TM6-TM7 (by +12°). A third interhelical angle: TM5-TM6 shows a trend, changing by -9°. In the transition from inactive to active states, average van der Waals interactions between TM3 and TM7 significantly increase as the average distance between them decreases by >2 Å. Average H-bonding between TM3 and TM6 decreases but is seemingly compensated by an increase in H-bonding between TM5 and TM6. In five Class A GPCRs, crystallized in both active and inactive states, increased H-bonding of agonists to TM6 and TM7, relative to antagonists, is observed. These protein-agonist interactions likely favour a change in the TM6-TM7 angle, which creates a narrowing in the binding pocket of activated receptors and an average ~200 Å3 reduction in volume.ConclusionsIn terms of similar conformational changes and agonist binding pattern, Class A GPCRs appear to share a common mechanism of activation, which can be exploited in future drug development.Electronic supplementary materialThe online version of this article (doi:10.1186/s12859-015-0567-3) contains supplementary material, which is available to authorized users.

Geometrical feature analysis of Co-Cr-Mo single tracks after selective laser melting processing

Purpose – Therefore, the purpose of this study is to understand the relationships between the processing parameters and the geometric form of the produced single tracks, in order to control dimensional quality in future experimentations. The quality of the deposited single track and layer is of prime importance in the selective laser melting (SLM) process, as it affects the product quality in terms of dimensional precision and product performance. Design/methodology/approach – In this paper, a vertical milling machining center equipped with an Ytterbium-fiber laser was used in the SLM experimentation to form single cobalt-chromium-molybdenum (CoCrMo) tracks. The different geometric features and the influence of the scanning parameters on these morphologic characteristics were studied statistically by means of ANOVA. Findings – Evidently, track height (h1) inaccuracy reduced in layer thicknesses between 100 and 200 μm. The re-melt depth (h2) was determined by the energy parameters, with laser power of 325-350 W and scanning speed (SS) of 66.6-83.3 mm/s being the most favorable parameters to obtain the required anchoring. Moreover, a contact angle of 117° was proposed as optimal, as it permitted an adequate overlapping region and a full densification, and, finally, an SS of 50 mm/s and a layer thickness of 250 were suggested for its development. Originality/value – The comprehension of the phenomena inherent to the process is related to the single track geometrical characteristics, which allow the definition of an optimal value for each factor for a further proposal of processing conditions that can finally derive a higher precision, wetting, density and mechanical properties.

What Do Thirty-One Columns Say about a “Theoretical” Thirty-Second?

Over the past three decades, the introduction of digital technologies in the field of architectural documentation has profoundly changed tools and acquisition techniques. Most of the developments concern metrical and colorimetric characteristics of the objects studied. These developments, surrounding the practice of architectural survey, tend to respond primarily to the requirements of completeness. In this context, it seems necessary to assess the impact of these instruments on the cognitive value of architectural representation. With a strong technological presence, the study of the built heritage is facing a problem of “information overload.” Indeed, this strong technological presence fails to strengthen representation in its role as a vehicle of knowledge. Confronted with the intelligibility deficit, this article proposes an original approach for reading morphological features of an artifact by using a bottom-up approach: the meaning of elements (i.e., their semantic layouts) come from a statistical analysis of the major shape discontinuities of a collection of instances. The idea is to rely on data accumulation to render apparent high-level semantic structures from the comparative analysis of common low-level geometric features. The principles introduced are illustrated by the study of 31 columns of the cloister of the abbey of Saint-Michel-de-Cuxa. To summarize, the first objective is to understand how digital technologies can help us in the analysis of artistic and technical production of Romanesque columns. The second objective is to automatically identify the common semantic articulations of the entire collection to build a reference model for the future assessment of each artifact.

Algorithmically generated rodent hepatic vascular trees in arbitrary detail.

Physiologically realistic geometric models of the vasculature in the liver are indispensable for modelling hepatic blood flow, the main connection between the liver and the organism. Current in vivo imaging techniques do not provide sufficiently detailed vascular trees for many simulation applications, so it is necessary to use algorithmic refinement methods. The method of Constrained Constructive Optimization (CCO) (Schreiner et al., 2006) is well suited for this purpose. Its results after calibration have been previously compared to experimentally acquired human vascular trees (Schwen and Preusser, 2012). The goal of this paper is to extend this calibration to the case of rodents (mice and rats), the most commonly used animal models in liver research. Based on in vivo and ex vivo micro-CT scans of rodent livers and their vasculature, we performed an analysis of various geometric features of the vascular trees. Starting from pruned versions of the original vascular trees, we applied the CCO procedure and compared these algorithmic results to the original vascular trees using a suitable similarity measure. The calibration of the postprocessing improved the algorithmic results compared to those obtained using standard CCO. In terms of angular features, the average similarity increased from 0.27 to 0.61, improving the total similarity from 0.28 to 0.40. Finally, we applied the calibrated algorithm to refine measured vascular trees to the (higher) level of detail desired for specific applications. Having successfully adapted the CCO algorithm to the rodent model organism, the resulting individual-specific refined hepatic vascular trees can now be used for advanced modeling involving, e.g., detailed blood flow simulations.

Dynamics Simulations with Spin-Flip Time-Dependent Density Functional Theory: Photoisomerization and Photocyclization Mechanisms of cis-Stilbene in ππ* States

On-the-fly dynamics simulations were carried out using spin-flip time dependent density functional theory (SF-TDDFT) to examine the photoisomerization and photocyclization mechanisms of cis-stilbene following excitation to the ππ* state. A state tracking method was devised to follow the target state among nearly degenerate electronic states during the dynamics simulations. The steepest descent path from the Franck-Condon structure of cis-stilbene in the ππ* state is shown to reach the S1-minimum of 4,4-dihydrophenanthrene (DHP) via a cis-stilbene-like structure (referred to as (S1)cis-min) on a very flat region of the S1-potential energy surface. From the dynamics simulations, the branching ratio of the photoisomerization is calculated as trans:DHP = 35:13, in very good agreement with the experimental data, trans:DHP = 35:10. The discrepancy between the steepest descent pathway and the significant trans-stilbene presence in the branching ratio observed experimentally and herein computationally is clarified from an analysis of geometrical features along the reaction pathway, as well as the low barrier of 0.1 eV for the pathway from (S1)cis-min to the twisted pyramidal structure on the S1-potential energy surface. It is concluded that ππ*-excited cis-stilbene propagates primarily toward the twisted structural region due to dynamic effects, with partial branching to the DHP structural region via the flat-surface region around (S1)cis-min.

Testing the limits of micro-scale analyses of Si stable isotopes by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry with application to rock weathering

An analytical protocol for accurate in-situ Si stable isotope analysis has been established on a new second-generation custom-built femtosecond laser ablation system. The laser was coupled to a multicollector inductively coupled plasma mass spectrometer (fsLA-MC-ICP-MS). We investigated the influence of laser parameters such as spot size, laser focussing, energy density and repetition rate, and ICP-MS operating conditions such as ICP mass load, spectral and non-spectral matrix effects, signal intensities, and data processing on precision and accuracy of Si isotope ratios. We found that stable and reproducible ICP conditions were obtained by using He as aerosol carrier gas mixed with Ar/H2O before entering the plasma. Precise δ29Si and δ30Si values (better than ±0.23‰, 2SD) can be obtained if the area ablated is at least 50×50μm; or, alternatively, for the analysis of geometric features down to the width of the laser spot (about 20μm) if an equivalent area is covered. Larger areas can be analysed by rastering the laser beam, whereas small single spot analyses reduce the attainable precision of δ30Si to ca. ±0.6‰, 2SD, for <30μm diameter spots. It was found that focussing the laser beam beneath the sample surface with energy densities between 1 and 3.8J/cm2 yields optimal analytical conditions for all materials investigated here. Using pure quartz (NIST 8546 aka. NBS-28) as measurement standard for calibration (standard-sample-bracketing) did result in accurate and precise data of international reference materials and samples covering a wide range in chemical compositions (Si single crystal IRMM-017, basaltic glasses KL2-G, BHVO-2G and BHVO-2, andesitic glass ML3B-G, rhyolitic glass ATHO-G, diopside glass JER, soda-lime glasses NIST SRM 612 and 610, San Carlos olivine). No composition-dependent matrix effect was discernible within uncertainties of the method.The method was applied to investigate the Si isotope signature of rock weathering at the micro-scale in a corestone sampled from a highly weathered roadcut profile in the tropical Highlands of Sri Lanka. The results show that secondary weathering products accumulated in cracks and grain boundaries are isotopically lighter than their unweathered plagioclase host, consistent with isotopically heavy dissolved Si found in rivers.

Study on Feature Extraction Methods Based on Motion Capture Data

By the analysis of motion Geometric features and Continuing feature that the motion capture data of the BVH format showed,Motion feature extraction method was proposed in this paper to preserve the motion original features in the maximum extent and marked motion data,improved the speed of motion data retrieval,and also provided a new method for rendering of motion characters in the virtual environment.

Speed reduction in school zones

The purpose of this study was to determine the effectiveness of flasher beacons in reducing vehicle speeds in Kentucky. Speed measurements were made during flashing and nonflashing periods at 48 locations. The physical characteristics of each site were identified and compared to speed reductions. In Kentucky, pedestrians between the ages of 5 and 9 represent less than 10 percent of the total population but account for more than 16 percent of all pedestrian fatalities. Fourteen findings and conclusions were based on analysis of physical and geometric features of the sample locations.

Root Cause Analysis of Product Service Failures in Design-A Closed-loop Lifecycle Modelling Approach

A number of industries including aerospace, telecom and automotive incur warranty and product return costs due to product malfunctions in service, which can also negatively impact customer satisfaction and loyalty. Product failures, which occur in service, are often caused by root causes at design or at manufacturing phases. Therefore a novel inter-loop modelling framework is needed which takes information from different phases to determine root causes and corrective actions. This goes beyond current intra-loop methods such as design optimization, statistical process control etc., which uses information from a single phase to address failures in the same phase. However, inter-loop modelling poses the challenge of integrating heterogeneous data from different phases of lifecycle with product and process models to determine failure root causes and corrective actions. To deal with failures in service, this paper proposes Closed-loop Lifecycle Modelling approach, specifically integrating information from service and design. Related work on fault diagnosis and corrections is also reviewed in the context of intra and inter loops of product lifecycle.The proposed methodology addresses root cause analysis (RCA) of service failures caused due to dimensional variations of product features. RCA identifies critical geometric features of internal components, which affects dimensional variations of product features. This is done by integrating warranty data from service to design models such as CAD, Geometric Dimensioning & Tolerancing (GD&T) etc. Steps of the methodology include: (i) identification of faulty product features from the Ishikawa diagram of the failure reported in warranty; (ii) variation simulation analysis of geometric features of internal components; (iii) determination of critical geometric features affecting faulty product feature via surrogate modelling of dimensional variations; and (iv) analyzing sensitivity of faulty product features on critical geometric features. The proposed Design-Service inter loop is demonstrated by an industrial case study of automotive ignition switch and ‘Sticky Key’ service failure. RCA of ‘Sticky Key’ issue identifies critical geometric features and their sensitivity in affecting the faulty product features, which cause the failure.

A Method for Quantitative Analysis of Geometrical Structure of Animal Organs in Meso-Scale: The Dung Beetle Foreleg End Tooth as a Case Example

The geometrical shapes of some animal organs have distinguished functions and properties that can provide useful information for bionic engineering applications. Hence, it is necessary to quantitatively measure the geometrical structure of those animal organs. However, some of the animal organs are tiny, complex and in the Meso-scale (0.1~10 mm). Their potential bionic application requires an accurate and efficient method to quantitatively analysis of their geometrical shapes. But existing methods are difficult and inefficient to quantitatively analysis. Yet, it was found that MATLAB image processing and computer vision technique can be advantageously exploited to obtain outer margin geometrical information from stereomicroscopy photograph. In this work, based on MATLAB, a program was designed and a method was proposed that specified for extract meso-scale animal organ outer margin contour points. The procedure for obtaining quantified geometrical information can be conclude as that stereomicroscope image of bionic object animal organ was prepared, the image to reduce noise interference was processed, the outer edge contour points was detected, and the points x and y coordinates data to computer database was stored. The foreleg of dung beetle Copris ochus Motschulsky, which is with special tooth-like structure for burrowing, the height of the end tooth is only around 1 mm and the width is about 0.5 mm, supported by this method, the outer edge profile of the foreleg end tooth was extracted from stereomicroscopy image with 669 × 727 pixels, about 1500 outer edge contour points was obtained, points x and y coordinates data were inputted to computer database for further analysis. This method is efficient, accurate and easy to adapt to quantitatively analysis of geometrical characteristic features of other animal organs in meso-scale.

Hypovigilance Detection Based on Eyelids Behavior Study

The supervision of people in special circumstances, having as their purpose detecting risk situations, is an area which has many applications. In this context we are interested, in this paper, the problems of driver drowsiness detection based on video analysis. We describe a new approach to detect reduced alertness automatically, to prevent the driver. Unlike many other works, our noninvasively approach is based only on the analysis of geometric features captured form faces video sequence without any electronics elements related to human.

Geometrical Feature Analysis of the Movement of the New Type of Double-Hemisphere Rolling Gear Globoidal Cam Indexing Mechanism

A novel kind of double-hemisphere rolling gear globoidal indexing cam mechanism was proposed，which can satisfy high speed and precision motion requirement. Fundamental principle and meshing characteristics were studied based on conjugate surface principle. Pure rolling of the transmision mechanism was applicated in engineering，and combination property was improved.

2M1-phlogopite from Black Hills (South Australia): The first case of configurational polytype in micas

The 2 M 1 -phlogopite from the potassic gabbronorite (Black Hill, Australia) has been studied by electron microprobe and single-crystal X-ray diffraction analyses. The crystal-chemical formula was (K 0.95 Na 0.01 )(Al 0.15 Mg 1.27 Fe 2+ 1.16 Fe 3+ 0.04 Ti 4+ 0.38 )(Si 2.85 Al 1.15 )O 10.76 F 0.11 Cl 0.03 OH 1.10 . The structural analysis has shown that the crystal has the cell parameters a = 5.352(1), b = 9.268(1), c = 20.168(1) A, and β = 95.10(1)° and exhibits symmetry lowering from the ideal space group C 2/ c to C 1. An octahedral cation ordering pattern was revealed from the refined site-scattering powers. Specifically, using the scattering species Mg vs. Fe, it was found that the M1 site at z = 0 was occupied principally by Mg (~77%) and subordinately by Fe (~23%), whereas that at z = 0.5 was completely occupied by Fe; the M2 sites at z = 0 displayed ~88% Mg and ~12% Fe, whereas those at z = 0.5 were occupied by ~86% Fe and ~14% Mg. The analysis of geometrical features shows that the Ti uptake in the structure via the Ti-oxy mechanism induces structural distortions of different extents on the z = 0 and z = 0.5 layers, with stronger effects for the layer at z = 0. Minor chemical and structural differences, instead, affect the T sheets at z = 0 and z = 0.5.

Additive manufacturing technology and material selection for direct manufacture of products based on computer aided design geometric feature analysis

This paper presents research into the development of an algorithm developed in a Visual Basic programming environment that aids in the selection of materials processed using additive manufacturing (AM) technologies. AM technologies such as selective laser sintering (SLS) and fused deposition modelling (FDM) have limitations on the materials available to them and each system has factors that limit the geometric freedom of the components that they can produce. Thus, materials capable of being processed on these types of technology can be selected through a method of traversing the geometric features of a computer aided design (CAD) model and performing an analysis of each individual feature’s attributes. The algorithm developed for this research uses data based on minimum feature size and a model bounding box as criteria in the selection of suitable materials. Through integration with an existing commercially available CAD software package, a component can be automatically analysed for its geometric feature properties and attributes, returning suitable AM systems and material information for selection by the operator. A number of case studies are presented that highlight the successful operation of the AM technology and material selection tool that has been developed.

Vein development during folding in the upper brittle crust: The case of tourmaline-rich veins of eastern Elba Island, northern Tyrrhenian Sea, Italy

Detailed structural analysis of tourmaline-rich veins hosted in the contact aureole of the ∼6 Ma Porto Azzurro granite in southeastern Elba Island, northern Tyrrhenian Sea is presented. Using geometric features of the veins, the physical conditions at the time of vein formation are estimated, namely the stress ratio (Φ = ( σ 2 − σ 3)/( σ 1 − σ 3)), driving stress ratio ( R′ = ( P f − σ 3)/( σ 1 − σ 3)) and fluid overpressure (Δ P o = P f − σ 3). Two vein sets (A veins and B veins) have been recognized based on orientation and thickness distributions and infilling material. Analysis of vein pole distributions indicates Φ = 0.57 and R′ = 0.24 for the A veins and Φ = 0.58 and R′ = 0.47 for the B veins, and fluid pressures less than the intermediate stress magnitude. Analysis of geometric features of the veins gives estimated fluid overpressures of between ∼16 MPa (A veins) and ∼32 MPa (B veins). We propose a model for the tectonic environment of vein development, in which formation of secondary permeability in the deforming thermal aureole of the Porto Azzurro pluton was controlled by ongoing development of fracture systems in the hinge zone of a regional NNW–SSE trending fold that favored transport and localization of hydrothermal fluids.