Geometric Topology and Shape Theory
Segal, Jack
1987-01-01
The aim of this international conference the third of its type was to survey recent developments in Geometric Topology and Shape Theory with an emphasis on their interaction. The volume contains original research papers and carefully selected survey of currently active areas. The main topics and themes represented by the papers of this volume include decomposition theory, cell-like mappings and CE-equivalent compacta, covering dimension versus cohomological dimension, ANR's and LCn-compacta, homology manifolds, embeddings of continua into manifolds, complement theorems in shape theory, approximate fibrations and shape fibrations, fibered shape, exact homologies and strong shape theory.
Armbruster, Diana; Suchert, Vivien; Gärtner, Anne; Strobel, Alexander
2014-08-01
The fast and reliable neuronal and behavioral responses to negative affective stimuli have been suggested to be at least partly based on the processing of simple geometric configurations within complex visual stimuli. In this context, one line of experimental and neuroimaging evidence suggests that simple V-shaped stimuli result in patterns of neuronal activation and behavioral responses akin to pictures of negative facial expressions. The present study investigated the effects of circles as well as upward and downward pointing triangles in healthy young adults on three peripheral physiological markers - skin conductance response (SCR), facial EMG, and startle reflex - in order to further narrow the gap between neuroimaging findings and behavioral data regarding the impact of geometric shapes. We found significant effects of geometric forms on the startle reflex (p≤0.001, η(2)=0.080) and the SCR (p=0.029, η(2)=0.078), but not on facial EMG. Furthermore, subjective valence and arousal ratings of geometric stimuli differed significantly, with downward pointing triangles being perceived as less pleasant and more arousing. In sum, our findings provide further evidence that simple geometric shapes convey emotional meaning. Particularly, the observed changes in SCR and startle response underscore the notion that geometric shapes lead to preparatory changes in physiological activation patterns, which are essential for facilitation of appropriate behavioral responses. However, the smaller effect sizes compared to more realistic affective pictures also highlight the organisms' ability to differentiate between real impending danger and abstract cues in order to avoid unnecessary excessive responses. Copyright © 2014 Elsevier Inc. All rights reserved.
Scale effect and geometric shapes of grains
Institute of Scientific and Technical Information of China (English)
GUO Hui; GUO Xing-ming
2007-01-01
The rule-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.
Shape configuration and category-specificity
DEFF Research Database (Denmark)
Gerlach, Christian; Law, Ian; Paulson, Olaf B.
2006-01-01
We examined the neural correlates of visual shape configuration, the binding of local shape characteristics into wholistic object descriptions, by comparing the regional cerebral blood flow associated with recognition of outline drawings and fragmented drawings. We found no areas that responded m...
Sturz, Bradley R; Edwards, Joshua E; Boyer, Ty W
2014-01-01
Nativists have postulated fundamental geometric knowledge that predates linguistic and symbolic thought. Central to these claims is the proposal for an isolated cognitive system dedicated to processing geometric information. Testing such hypotheses presents challenges due to difficulties in eliminating the combination of geometric and non-geometric information through language. We present evidence using a modified matching interference paradigm that an incongruent shape word interferes with identifying a two-dimensional geometric shape, but an incongruent two-dimensional geometric shape does not interfere with identifying a shape word. This asymmetry in interference effects between two-dimensional geometric shapes and their corresponding shape words suggests that shape words activate spatial representations of shapes but shapes do not activate linguistic representations of shape words. These results appear consistent with hypotheses concerning a cognitive system dedicated to processing geometric information isolated from linguistic processing and provide evidence consistent with hypotheses concerning knowledge of geometric properties of space that predates linguistic and symbolic thought.
Geometric shapes and relationships of some one-body and multibody leptodermous distributions
Royer, G.; Mokus, N.; Jahan, J.
2017-05-01
Different families of geometric shapes, derived mainly from lemniscatoids, are proposed to describe ground and excited states of leptodermous distributions of nuclear matter. The transition from one spherical or ellipsoidal nucleus to several spherical or ellipsoidal nuclei or vice versa (in the decay and entrance channels of nuclear reactions: fission, fusion, and fragmentation) is particularly investigated. The geometric characteristics of these configurations are given, allowing calculations of the system energy, dynamics of the reactions, and angular distribution of the fragments.
Geometrical Correlation and Matching of 2d Image Shapes
Vizilter, Y. V.; Zheltov, S. Y.
2012-07-01
The problem of image correspondence measure selection for image comparison and matching is addressed. Many practical applications require image matching "just by shape" with no dependence on the concrete intensity or color values. Most popular technique for image shape comparison utilizes the mutual information measure based on probabilistic reasoning and information theory background. Another approach was proposed by Pytiev (so called "Pytiev morphology") based on geometrical and algebraic reasoning. In this framework images are considered as piecewise-constant 2D functions, tessellation of image frame by the set of non-intersected connected regions determines the "shape" of image and the projection of image onto the shape of other image is determined. Morphological image comparison is performed using the normalized morphological correlation coefficients. These coefficients estimate the closeness of one image to the shape of other image. Such image analysis technique can be characterized as an ""ntensity-to-geometry" matching. This paper generalizes the Pytiev morphological approach for obtaining the pure "geometry-to-geometry" matching techniques. The generalized intensity-geometrical correlation coefficient is proposed including the linear correlation coefficient and the square of Pytiev correlation coefficient as its partial cases. The morphological shape correlation coefficient is proposed based on the statistical averaging of images with the same shape. Centered morphological correlation coefficient is obtained under the condition of intensity centering of averaged images. Two types of symmetric geometrical normalized correlation coefficients are proposed for comparison of shape-tessellations. The technique for correlation and matching of shapes with ordered intensities is proposed with correlation measures invariant to monotonous intensity transformations. The quality of proposed geometrical correlation measures is experimentally estimated in the task of
GEOMETRICAL CORRELATION AND MATCHING OF 2D IMAGE SHAPES
Y. V. Vizilter; S. Y. Zheltov
2012-01-01
The problem of image correspondence measure selection for image comparison and matching is addressed. Many practical applications require image matching "just by shape" with no dependence on the concrete intensity or color values. Most popular technique for image shape comparison utilizes the mutual information measure based on probabilistic reasoning and information theory background. Another approach was proposed by Pytiev (so called "Pytiev morphology") based on geometrical and algebraic r...
Energy Technology Data Exchange (ETDEWEB)
Xiao, Ye; Huang, Zaixing, E-mail: huangzx@nuaa.edu.cn [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing (China)
2015-11-15
The equilibrium configuration equations of DNA chain with elastic rod model are derived in detail by the variation of the free energy functional, which depends on the curvature, torsion, twisting angle and its derivative with respect to the arc-length of central axis curve of rod. With the different shapes of rod, we obtain the equilibrium equations of DNA with circular and noncircular cross sections, which provide an approach to describe the physical behaviors of A-, B-, Z-DNA. The results show that the elastic rod model with circular cross section can accurately characterize the equilibrium configurations of A-, B-DNA, while the model with elliptical cross sections is more suitable for Z-DNA.
Shaping tissues by balancing active forces and geometric constraints
Foolen, Jasper; Yamashita, Tadahiro; Kollmannsberger, Philip
2016-02-01
The self-organization of cells into complex tissues during growth and regeneration is a combination of physical-mechanical events and biochemical signal processing. Cells actively generate forces at all stages in this process, and according to the laws of mechanics, these forces result in stress fields defined by the geometric boundary conditions of the cell and tissue. The unique ability of cells to translate such force patterns into biochemical information and vice versa sets biological tissues apart from any other material. In this topical review, we summarize the current knowledge and open questions of how forces and geometry act together on scales from the single cell to tissues and organisms, and how their interaction determines biological shape and structure. Starting with a planar surface as the simplest type of geometric constraint, we review literature on how forces during cell spreading and adhesion together with geometric constraints impact cell shape, stress patterns, and the resulting biological response. We then move on to include cell-cell interactions and the role of forces in monolayers and in collective cell migration, and introduce curvature at the transition from flat cell sheets to three-dimensional (3D) tissues. Fibrous 3D environments, as cells experience them in the body, introduce new mechanical boundary conditions and change cell behaviour compared to flat surfaces. Starting from early work on force transmission and collagen remodelling, we discuss recent discoveries on the interaction with geometric constraints and the resulting structure formation and network organization in 3D. Recent literature on two physiological scenarios—embryonic development and bone—is reviewed to demonstrate the role of the force-geometry balance in living organisms. Furthermore, the role of mechanics in pathological scenarios such as cancer is discussed. We conclude by highlighting common physical principles guiding cell mechanics, tissue patterning and
Shape configuration and category-specificity
DEFF Research Database (Denmark)
Gerlach, Christian; Law, Ian; Paulson, Olaf B
2006-01-01
and fragmented drawings. We also examined whether fragmentation had different impact on the recognition of natural objects and artefacts and found that recognition of artefacts was more affected by fragmentation than recognition of natural objects. Thus, the usual finding of an advantage for artefacts...... a recent account of category-specificity and lends support to the notion that category-specific impairments can occur for both natural objects and artefacts following damage to pre-semantic stages in visual object recognition. The implications of the present findings are discussed in relation to theories...
Shape configuration and category-specificity
DEFF Research Database (Denmark)
Gerlach, Christian; Law, I; Paulson, Olaf B.
2006-01-01
in difficult object decision tasks, which is also found in the present experiments with outlines, is reversed when the stimuli are fragmented. This interaction between category (natural versus artefacts) and stimulus type (outlines versus fragmented forms) is in accordance with predictions derived from...... a recent account of category-specificity and lends support to the notion that category-specific impairments can occur for both natural objects and artefacts following damage to pre-semantic stages in visual object recognition. The implications of the present findings are discussed in relation to theories...
Geometrizing configurations. Heinrich Hertz and his mathematical precursors
DEFF Research Database (Denmark)
Lützen, Jesper
1999-01-01
A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics......A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics...
2011-08-15
small numbers of sensed features associated with locations on the target geometry, although we plan to consider larger point clouds , or even...Correspondence Problem 7. Shapelets 8. Point Clouds 9. 3D Shape Reconstruction and Shape from Motion 10. Probability and Statistics of Shape...ideas can be used to align ladar data to CAD models and to speed various algorithms for matching point clouds to target models. In some cases it can be
Betti, R; Cerri, A; Vergani, R; Agape, E; Menni, S
2015-07-01
Geometric shapes have been suggested to be found in malignant melanomas. We have observed a number of melanomas presenting with linear and incomplete angulated figures. To verify the assumption that geometric shapes, a linear border and/or incomplete angulated figures may indicate a potential melanoma. Patients with surgically removed melanocytic lesions were admitted to the study. We evaluated the presence of a sharp linear demarcation, the presence of contiguous lines resulting in the formation of angle/s and the presence of complete geometric figure. We distinguished the obtained results into melanoma and benign melanocytic naevi. A total of 471 melanomas and 1979 melanocytic naevi were collected. Linear borders, angles and geometric figures were observed in 42 melanomas and in 75 benign melanocytic naevi. Angles with incomplete geometric configuration were observed in 21 melanomas and in 37 benign naevi (21/471 vs. 37/1979, 4.24% vs. 1.87%; P geometrical figures in 12 melanomas and 17 naevi (12/471 vs. 17/1979, 2.54% vs. 0.85%; P geometrical configurations might indicate a suspect melanoma. Only sharp linear demarcation of the lesion do not seem to be significantly associated with melanoma suspicion. © 2014 European Academy of Dermatology and Venereology.
Bledsoe, Gloria J
1987-01-01
The game of "Guess What" is described as a stimulating vehicle for students to consider the unifying or distinguishing features of geometric figures. Teaching suggestions as well as the gameboard are provided. (MNS)
Institute of Scientific and Technical Information of China (English)
QiuWei; KangYilan; SunQingchi; QinQinghua; LinYu
2004-01-01
Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure.In this paper, the stress distribution of a multilayer piezoelectric composite is investigated in a working environment and the optimized geometrical configuration of the piezoelectric layer is obtained. The stress distribution in the structure and the stress concentration near the edge of the internal electrode, induced by non-uniform electric field distribution, are analyzed by moirá interferometry experiment and finite element numerical simulation. Based on the above analysis,two optimized geometrical models are presented for the purpose of geometrical configuration selection, with which stress concentration can be reduced significantly while the feasibility of the machining process and the basic structural functions occurring in the conventional model are retained. The numerical results indicate that the maximum stress in the optimized models is effectively diminished compared to the conventional model. For instance, the peak value of the principal stress in the optimized model Ⅱ is 93.1% smaller than that in the conventional model.It is proved that stress concentration can be effectively relaxed in the latter of the two optimized models and thus the probability of fracture damage can be decreased.
Overview of Sensitivity Analysis and Shape Optimization for Complex Aerodynamic Configurations
Newman, Perry A.; Newman, James C., III; Barnwell, Richard W.; Taylor, Arthur C., III; Hou, Gene J.-W.
1998-01-01
This paper presents a brief overview of some of the more recent advances in steady aerodynamic shape-design sensitivity analysis and optimization, based on advanced computational fluid dynamics. The focus here is on those methods particularly well- suited to the study of geometrically complex configurations and their potentially complex associated flow physics. When nonlinear state equations are considered in the optimization process, difficulties are found in the application of sensitivity analysis. Some techniques for circumventing such difficulties are currently being explored and are included here. Attention is directed to methods that utilize automatic differentiation to obtain aerodynamic sensitivity derivatives for both complex configurations and complex flow physics. Various examples of shape-design sensitivity analysis for unstructured-grid computational fluid dynamics algorithms are demonstrated for different formulations of the sensitivity equations. Finally, the use of advanced, unstructured-grid computational fluid dynamics in multidisciplinary analyses and multidisciplinary sensitivity analyses within future optimization processes is recommended and encouraged.
Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang
2015-01-05
A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS.
Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang
2015-01-01
A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS. PMID:25557721
Ozkan, Aysegul; Sitharam, Meera; Kurnikova, Maria
2014-01-01
EASAL (efficient atlasing and sampling of assembly landscapes) is a recently reported geometric method for representing, visualizing, sampling and computing integrals over the potential energy landscape tailored for small molecular assemblies. EASAL's efficiency arises from the fact that small assembly landscapes permit the use of so-called Cayley parameters (inter-atomic distances) for geometric representation and sampling of the assembly configuration space regions; this results in their isolation, convexification, customized sampling and systematic traversal using a comprehensive topological roadmap. By sampling the assembly landscape of 2 TransMembrane Helices, with short-range pair-potentials, this paper demonstrates that EASAL provides reasonable coverage of crucial but narrow regions of low effective dimension with much fewer samples and computational resources than traditional MonteCarlo or Molecular Dynamics based sampling. Promising avenues are discussed, for combining the complementary advantages o...
Budday, Dominik; Leyendecker, Sigrid; van den Bedem, Henry
2015-10-01
Proteins operate and interact with partners by dynamically exchanging between functional substates of a conformational ensemble on a rugged free energy landscape. Understanding how these substates are linked by coordinated, collective motions requires exploring a high-dimensional space, which remains a tremendous challenge. While molecular dynamics simulations can provide atomically detailed insight into the dynamics, computational demands to adequately sample conformational ensembles of large biomolecules and their complexes often require tremendous resources. Kinematic models can provide high-level insights into conformational ensembles and molecular rigidity beyond the reach of molecular dynamics by reducing the dimensionality of the search space. Here, we model a protein as a kinematic linkage and present a new geometric method to characterize molecular rigidity from the constraint manifold Q and its tangent space Q at the current configuration q. In contrast to methods based on combinatorial constraint counting, our method is valid for both generic and non-generic, e.g., singular configurations. Importantly, our geometric approach provides an explicit basis for collective motions along floppy modes, resulting in an efficient procedure to probe conformational space. An atomically detailed structural characterization of coordinated, collective motions would allow us to engineer or allosterically modulate biomolecules by selectively stabilizing conformations that enhance or inhibit function with broad implications for human health.
Concealed configuration mixing and shape coexistence in the platinum nuclei
Energy Technology Data Exchange (ETDEWEB)
Garcia-Ramos, J. E.; Hellemans, V.; Heyde, K. [Departamento de Fisica Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Universite Libre de Bruxelles, Physique Nucleaire Theorique et Physique Mathematique, CP229, B-1050 Brussels (Belgium); Department of Physics and Astronomy, Ghent University, Proeftuinstraat 86, B-9000 Gent (Belgium)
2012-10-20
The role of configuration mixing in the Pt region is investigated. The nature of the ground state changes smoothly, being spherical around mass A{approx} 174 and A{approx} 192 and deformed around the mid-shell N= 104 region. Interacting Boson Model with configuration mixing calculations are presented for deformations and isotope shifts. The assumption of the existence of two configurations with very different deformation provides a simple framework to explain the observed isotope shifts systematics.
Marzougui, M.; Hammami, M.; Maad, R. Ben
2016-10-01
The main purpose of this study is focused on experimental investigation of cooling performance of various minichannel designs. The hydraulic dimension of one of the heat sink is 3 mm while that of the other is 2 mm. Deionised water was used as the coolant for studies conducted in both the heat sinks. Tests were done for a wide range of flow rates (0.7 l-9 l h-1) and heat inputs (5-40 kW/m2). Irrespective of the hydraulic diameter and the geometric configuration, profits and boundaries of each channel shape are analyzed and discussed in the clarity of experimental data. The total thermal resistance and the average heat transfer coefficient are compared for the various channels inspected.
Parametric geometric model and shape optimization of an underwater glider with blended-wing-body
Sun, Chunya; Song, Baowei; Wang, Peng
2015-11-01
Underwater glider, as a new kind of autonomous underwater vehicles, has many merits such as long-range, extended-duration and low costs. The shape of underwater glider is an important factor in determining the hydrodynamic efficiency. In this paper, a high lift to drag ratio configuration, the Blended-Wing-Body (BWB), is used to design a small civilian under water glider. In the parametric geometric model of the BWB underwater glider, the planform is defined with Bezier curve and linear line, and the section is defined with symmetrical airfoil NACA 0012. Computational investigations are carried out to study the hydrodynamic performance of the glider using the commercial Computational Fluid Dynamics (CFD) code Fluent. The Kriging-based genetic algorithm, called Efficient Global Optimization (EGO), is applied to hydrodynamic design optimization. The result demonstrates that the BWB underwater glider has excellent hydrodynamic performance, and the lift to drag ratio of initial design is increased by 7% in the EGO process.
Optimized geometric configuration of active ring laser gyroscopes
Gormley, John; Salloum, Tony
2016-05-01
We present a thorough derivation of the Sagnac effect for a ring laser gyroscope of any arbitrary polygonal configuration. We determine optimized alternative geometric configurations for the mirrors. The simulations incur the implementation of a lasing medium with the standard square system, triangular, pentagonal, and oblongated square configuration (diamond). Simulations of possible new geometric configurations are considered, as well as the possibility of adjusting the concavity of the mirrors.
Geometric constraints for shape and topology optimization in architectural design
Dapogny, Charles; Faure, Alexis; Michailidis, Georgios; Allaire, Grégoire; Couvelas, Agnes; Estevez, Rafael
2017-02-01
This work proposes a shape and topology optimization framework oriented towards conceptual architectural design. A particular emphasis is put on the possibility for the user to interfere on the optimization process by supplying information about his personal taste. More precisely, we formulate three novel constraints on the geometry of shapes; while the first two are mainly related to aesthetics, the third one may also be used to handle several fabrication issues that are of special interest in the device of civil structures. The common mathematical ingredient to all three models is the signed distance function to a domain, and its sensitivity analysis with respect to perturbations of this domain; in the present work, this material is extended to the case where the ambient space is equipped with an anisotropic metric tensor. Numerical examples are discussed in two and three space dimensions.
Taylor, Arthur C., III; Newman, James C., III; Barnwell, Richard W.
1997-01-01
A three-dimensional unstructured grid approach to aerodynamic shape sensitivity analysis and design optimization has been developed and is extended to model geometrically complex configurations. The advantage of unstructured grids (when compared with a structured-grid approach) is their inherent ability to discretize irregularly shaped domains with greater efficiency and less effort. Hence, this approach is ideally suited for geometrically complex configurations of practical interest. In this work the nonlinear Euler equations are solved using an upwind, cell-centered, finite-volume scheme. The discrete, linearized systems which result from this scheme are solved iteratively by a preconditioned conjugate-gradient-like algorithm known as GMRES for the two-dimensional geometry and a Gauss-Seidel algorithm for the three-dimensional; similar procedures are used to solve the accompanying linear aerodynamic sensitivity equations in incremental iterative form. As shown, this particular form of the sensitivity equation makes large-scale gradient-based aerodynamic optimization possible by taking advantage of memory efficient methods to construct exact Jacobian matrix-vector products. Simple parameterization techniques are utilized for demonstrative purposes. Once the surface has been deformed, the unstructured grid is adapted by considering the mesh as a system of interconnected springs. Grid sensitivities are obtained by differentiating the surface parameterization and the grid adaptation algorithms with ADIFOR (which is an advanced automatic-differentiation software tool). To demonstrate the ability of this procedure to analyze and design complex configurations of practical interest, the sensitivity analysis and shape optimization has been performed for a two-dimensional high-lift multielement airfoil and for a three-dimensional Boeing 747-200 aircraft.
Institute of Scientific and Technical Information of China (English)
YUAN Zhe; SU Chang-Rong; ZHANG Shi-Zhong; LI Jia-Ming
2004-01-01
@@ Using the first-principle molecular dynamics simulations, we have studied the molecular geometrical configurations as well as the corresponding electronic structures of a single molecule device assembled by the mechanically controllable break junction technique with variations of the electrode distance. There are some very interesting features varying with the electrode distance.
Kalenine, Solene; Pinet, Leatitia; Gentaz, Edouard
2011-01-01
This study assessed the benefit of a multisensory intervention on the recognition of geometrical shapes in kindergarten children. Two interventions were proposed, both conducted by the teachers and involving exercises focused on the properties of the shapes but differing in the sensory modalities used to explore them. In the "VH" intervention, the…
Reasoning with Geometric Shapes
Seah, Rebecca
2015-01-01
Geometry belongs to branches of mathematics that develop students' visualisation, intuition, critical thinking, problem solving, deductive reasoning, logical argument and proof (Jones, 2002). It provides the basis for the development of spatial sense and plays an important role in acquiring advanced knowledge in science, technology, engineering,…
Directory of Open Access Journals (Sweden)
Seth M. Weinberg
2013-11-01
Full Text Available Introduction: Previous research suggests that aspects of facial surface morphology are heritable. Traditionally, heritability studies have used a limited set of linear distances to quantify facial morphology and often employ statistical methods poorly designed to deal with biological shape. In this preliminary report, we use a combination of 3D photogrammetry and landmark-based morphometrics to explore which aspects of face shape show the strongest evidence of heritability in a sample of twins. Methods: 3D surface images were obtained from 21 twin pairs (10 monozygotic, 11 same-sex dizygotic. Thirteen 3D landmarks were collected from each facial surface and their coordinates subjected to geometric morphometric analysis. This involved superimposing the individual landmark configurations and then subjecting the resulting shape coordinates to a principal components analysis. The resulting PC scores were then used to calculate rough narrow-sense heritability estimates. Results: Three principal components displayed evidence of moderate to high heritability and were associated with variation in the breadth of orbital and nasal structures, upper lip height and projection, and the vertical and forward projection of the root of the nose due to variation in the position of nasion. Conclusions: Aspects of facial shape, primarily related to variation in length and breadth of central midfacial structures, were shown to demonstrate evidence of strong heritability. An improved understanding of which facial features are under strong genetic control is an important step in the identification of specific genes that underlie normal facial variation.
Canturk-Gunhan, Berna; Cetingoz, Duygu
2013-01-01
The purpose of this study is to examine preschool preservice teachers' subject matter knowledge (SMK) and pedagogical content knowledge (PCK) of basic geometric shapes. The study employed case study method in order to investigate preschool preservice teachers' SMK and PCK on geometric shapes in actual classroom environment and to describe the…
Mayer, Christine; Windhager, Sonja; Schaefer, Katrin; Mitteroecker, Philipp
2017-01-01
Facial markers of body composition are frequently studied in evolutionary psychology and are important in computational and forensic face recognition. We assessed the association of body mass index (BMI) and waist-to-hip ratio (WHR) with facial shape and texture (color pattern) in a sample of young Middle European women by a combination of geometric morphometrics and image analysis. Faces of women with high BMI had a wider and rounder facial outline relative to the size of the eyes and lips, and relatively lower eyebrows. Furthermore, women with high BMI had a brighter and more reddish skin color than women with lower BMI. The same facial features were associated with WHR, even though BMI and WHR were only moderately correlated. Yet BMI was better predictable than WHR from facial attributes. After leave-one-out cross-validation, we were able to predict 25% of variation in BMI and 10% of variation in WHR by facial shape. Facial texture predicted only about 3–10% of variation in BMI and WHR. This indicates that facial shape primarily reflects total fat proportion, rather than the distribution of fat within the body. The association of reddish facial texture in high-BMI women may be mediated by increased blood pressure and superficial blood flow as well as diet. Our study elucidates how geometric morphometric image analysis serves to quantify the effect of biological factors such as BMI and WHR to facial shape and color, which in turn contributes to social perception. PMID:28052103
Configurational forces and shape of a sessile droplet on a rotating solid substrate
Directory of Open Access Journals (Sweden)
Lubarda Vlado A.
2012-01-01
Full Text Available The shape of a uniformly rotating liquid droplet deposited on a solid substrate is determined by an iterative numerical integration of the governing nonlinear differential equation. The differential equation and the boundary conditions are derived by means of the variational analysis which delivers the expressions for the specific configurational force per unit area of the liquid/vapor interface, and the configurational force along the liquid/solid/vapor contact circle. An analytical proof for the orthogonality of the specific configurational force to the surface of the droplet is constructed. The effect of rotation on the droplet’s gyrostatic shape is discussed.
Annicchiarico, W
2001-01-01
Structural optimization is an engineering field which deal with the improvement of existing solutions or even more find new solutions that are better than the previous ones under some selected criterion. Shape optimization is a research area in this field and it is involved in developing new methodologies to find better structural design based on the shape as resistant element, as for example solutions with the less stress concentration zones and made with the minimum amount of material. The goal of this doctoral dissertation is to present and discuss a general structural shape optimization methodology able to optimize several structural systems or mechanical devices. The approach presented herein is based on global search optimization tools such as Genetic Algorithms and geometric design elements by means of beta-splines curves and surfaces representation. Finally the great versatility of the developed tool is presented and discussed with an application example.
Directory of Open Access Journals (Sweden)
Valeria P. Diawol
2015-03-01
Full Text Available Crustacean growth studies typically use modal analysis rather than focusing on the growth of individuals. In the present work, we use geometric morphometrics to determine how organism shape and size varies during the life of the freshwater crab, Aegla uruguayana Schmitt, 1942. A total of 66 individuals from diverse life cycle stages were examined daily and each exuvia was recorded. Digital images of the dorsal region of the cephalothorax were obtained for each exuvia and were subsequently used to record landmark configurations. Moult increment and intermoult period were estimated for each crab. Differences in shape between crabs of different sizes (allometry and sexes (sexual dimorphism; SD were observed. Allometry was registered among specimens; however, SD was not statistically significant between crabs of a given size. The intermoult period increased as size increased, but the moult frequency was similar between the sexes. Regarding ontogeny, juveniles had short and blunt rostrum, robust forehead region, and narrow cephalothorax. Unlike juveniles crabs, adults presented a well-defined anterior and posterior cephalothorax region. The rostrum was long and stylised and the forehead narrow. Geometric morphometric methods were highly effective for the analysis of aeglid-individual- growth and avoided excessive handling of individuals through exuvia analysis.
Aerodynamic shape parameterisation and optimisation of novel configurations
Straathof, M.H.; Van Tooren, M.J.L.; Voskuijl, M.; Koren, B.
2008-01-01
The Multi-Disciplinary Design Optimisation (MDO) process can be supported by partial automation of analysis and optimisation steps. Design and Engineering Engines (DEE) are useful concepts to structure this type of automation. Within the DEE, a product can be parameterically defined using Knowledge
Han, Kai; Zhang, Jin; Zhang, Weiyun; Wang, Shibo; Xu, Luming; Zhang, Chi; Zhang, Xianzheng; Han, Heyou
2017-03-28
Geometrical shape of nanoparticles plays an important role in cellular internalization. However, the applicability in tumor selective therapeutics is still scarcely reported. In this article, we designed a tumor extracellular acidity-responsive chimeric peptide with geometrical shape switch for enhanced tumor internalization and photodynamic therapy. This chimeric peptide could self-assemble into spherical nanoparticles at physiological condition. While at tumor extracellular acidic microenvironment, chimeric peptide underwent detachment of acidity-sensitive 2,3-dimethylmaleic anhydride groups. The subsequent recovery of ionic complementarity between chimeric peptides resulted in formation of rod-like nanoparticles. Both in vitro and in vivo studies demonstrated that this acidity-triggered geometrical shape switch endowed chimeric peptide with accelerated internalization in tumor cells, prolonged accumulation in tumor tissue, enhanced photodynamic therapy, and minimal side effects. Our results suggested that fusing tumor microenvironment with geometrical shape switch should be a promising strategy for targeted drug delivery.
Directory of Open Access Journals (Sweden)
Dimitri Neaux
Full Text Available The organization of the bony face is complex, its morphology being influenced in part by the rest of the cranium. Characterizing the facial morphological variation and craniofacial covariation patterns in extant hominids is fundamental to the understanding of their evolutionary history. Numerous studies on hominid facial shape have proposed hypotheses concerning the relationship between the anterior facial shape, facial block orientation and basicranial flexion. In this study we test these hypotheses in a sample of adult specimens belonging to three extant hominid genera (Homo, Pan and Gorilla. Intraspecific variation and covariation patterns are analyzed using geometric morphometric methods and multivariate statistics, such as partial least squared on three-dimensional landmarks coordinates. Our results indicate significant intraspecific covariation between facial shape, facial block orientation and basicranial flexion. Hominids share similar characteristics in the relationship between anterior facial shape and facial block orientation. Modern humans exhibit a specific pattern in the covariation between anterior facial shape and basicranial flexion. This peculiar feature underscores the role of modern humans' highly-flexed basicranium in the overall integration of the cranium. Furthermore, our results are consistent with the hypothesis of a relationship between the reduction of the value of the cranial base angle and a downward rotation of the facial block in modern humans, and to a lesser extent in chimpanzees.
A geometric morphometric analysis of cranial and mandibular shape variation of didelphid marsupials
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D. Astúa de Moraes
2000-06-01
Full Text Available Abstract The New World marsupial family Didelphidae is one of the oldest among mammals and is usually regarded as a morphologically conservative group. We analyzed cranial shape variation among six species of the six largest living genera of the family using two-dimensional landmark data. We captured and digitized video images of the skull and mandible for the following species: Caluromys philander (n = 65, Chironectes minimus (n = 30, Didelphis aurita (n = 70, Lutreolina crassicaudata (n = 37, Metachirus nudicaudatus (n = 77 and Philander frenata (n = 62. Fourteen landmarks were defined for the lateral, 25 for the ventral, 23 for the dorsal views of the skull, and nine on the mandibular lateral view. Sex, species, and interaction effects were analyzed with a two-way MANOVA on the matrices of coordinates aligned by general least squares. All four views had significant interactions. Canonical Variates Analysis was performed on sexes and species, and shape was regressed on the canonical variate scores for each species. Caluromys philander was clearly the most distinct species, with paedomorphic features that can be related to its arboreal habits. A conspicuous shortening of the rostrum distinguishes the highly carnivorous Lutreolina crassicaudata. Didelphis aurita and Philander frenata overlapped somewhat, reflecting shape similarities associated with their phylogenetic affinities, while the few differences observed are probably allometric consequences of size differences. Philander frenata and Chironectes minimus showed similar cranial shapes, while Metachirus nudicaudatus was distinctive with a broad and elongated rostrum. In spite of an overall similar shape, the geometric morphometric approach revealed several marked differences among species that can be related to their phylogenetic origin and their adaptive
Young Children's Understanding of Geometric Shapes: The Role of Geometric Models
Elia, Iliada; Gagatsis, Athanasios; Kyriakides, Leonidas
2003-01-01
In this paper, we explore the role of polygonal shapes as geometrical models in teaching mathematics, so as to elicit and interpret children's geometric conceptions and understanding about shapes. Primary pupils were asked to draw a stairway of figures (triangles, squares and rectangles) each one bigger than the preceding one. Pupils use two…
Geometric morphometrics of hominoid infraspinous fossa shape.
Green, David J; Serrins, Jesse D; Seitelman, Brielle; Martiny, Amy R; Gunz, Philipp
2015-01-01
Recent discoveries of early hominin scapulae from Ethiopia (Dikika, Woranso-Mille) and South Africa (Malapa) have motivated new examinations of the relationship between scapular morphology and locomotor function. In particular, infraspinous fossa shape has been shown to significantly differ among hominoids. However, this region presents relatively few homologous landmarks, such that traditional distance and angle-based methods may oversimplify this three-dimensional structure. To more thoroughly assess infraspinous fossa shape variation as it relates to function among adult hominoid representatives, we considered two geometric morphometric (GM) approaches--one employing five homologous landmarks ("wireframe") and another with 83 sliding semilandmarks along the border of the infraspinous fossa. We identified several differences in infraspinous fossa shape with traditional approaches, particularly in superoinferior fossa breadth and scapular spine orientation. The wireframe analysis reliably captured the range of shape variation in the sample, which reflects the relatively straightforward geometry of the infraspinous fossa. Building on the traditional approach, the GM results highlighted how the orientation of the medial portion of the infraspinous fossa differed relative to both the axillary border and spine. These features distinguished Pan from Gorilla in a way that traditional analyses had not been able to discern. Relative to the wireframe method, the semilandmark approach further distinguished Pongo from Homo, highlighting aspects of infraspinous fossa morphology that may be associated with climbing behaviors in hominoid taxa. These results highlight the ways that GM methods can enhance our ability to evaluate complex aspects of shape for refining and testing hypotheses about functional morphology.
Hamaya, K.; Taniyama, T.; Koike, T.; Yamazaki, Y.
2006-01-01
We study the effect of the shape anisotropy on the magnetic domain configurations of a ferromagnetic semiconductor (Ga,Mn)As/GaAs(001) epitaxial wire as a function of temperature. Using magnetoresistance measurements, we deduce the magnetic configurations and estimate the relative strength of the shape anisotropy compared with the intrinsic anisotropies. Since the intrinsic anisotropy is found to show a stronger temperature dependence than the shape anisotropy, the effect of the shape anisotr...
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Dipali Y Shah
2012-01-01
Full Text Available The C-shaped root canal system is an aberration of the root canal system in which a characteristic fin or web connects individual canals, resulting in a C-shaped cross section. This configuration has been rarely reported in the mandibular second premolar. The only other known reported case of a C-shaped canal, with its configuration, in relation to mandibular second premolar is of an extracted tooth. The purpose of this report is to describe the diagnosis, configuration and endodontic management of C-shaped root canal in mandibular second premolar. Clinical techniques to addresses the challenges in endodontic disinfection as well as cleaning and shaping of the C-shaped canal, which is prone to endodontic mishaps, are also discussed in this case report. Reporting of this case emphasizes the need and added advantage of using the dental operating microscope hand in hand with conventional radiography in management of the C-shaped root canal configuration.
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Jonathan D. Krieger
2014-08-01
Full Text Available Premise of the study: I present a protocol for creating geometric leaf shape metrics to facilitate widespread application of geometric morphometric methods to leaf shape measurement. Methods and Results: To quantify circularity, I created a novel shape metric in the form of the vector between a circle and a line, termed geometric circularity. Using leaves from 17 fern taxa, I performed a coordinate-point eigenshape analysis to empirically identify patterns of shape covariation. I then compared the geometric circularity metric to the empirically derived shape space and the standard metric, circularity shape factor. Conclusions: The geometric circularity metric was consistent with empirical patterns of shape covariation and appeared more biologically meaningful than the standard approach, the circularity shape factor. The protocol described here has the potential to make geometric morphometrics more accessible to plant biologists by generalizing the approach to developing synthetic shape metrics based on classic, qualitative shape descriptors.
Krieger, Jonathan D
2014-08-01
I present a protocol for creating geometric leaf shape metrics to facilitate widespread application of geometric morphometric methods to leaf shape measurement. • To quantify circularity, I created a novel shape metric in the form of the vector between a circle and a line, termed geometric circularity. Using leaves from 17 fern taxa, I performed a coordinate-point eigenshape analysis to empirically identify patterns of shape covariation. I then compared the geometric circularity metric to the empirically derived shape space and the standard metric, circularity shape factor. • The geometric circularity metric was consistent with empirical patterns of shape covariation and appeared more biologically meaningful than the standard approach, the circularity shape factor. The protocol described here has the potential to make geometric morphometrics more accessible to plant biologists by generalizing the approach to developing synthetic shape metrics based on classic, qualitative shape descriptors.
Kokshenev, V B; García, G J M
2003-01-01
A natural similarity in body dimensions of terrestrial animals noticed by ancient philosophers remains the main key to the problem of mammalian skeletal evolution with body mass explored in theoretical and experimental biology and tested by comparative zoologists. We discuss the long-standing problem of mammalian bone allometry commonly studied in terms of the so-called ''geometric'', ''elastic'', and ''static stress'' similarities by McMahon (1973, 1975a, 1975b). We revise the fundamental assumptions underlying these similarities and give new physical insights into geometric-shape and elastic-force constraints imposed on spatial evolution of mammalian long bones.
Influence of Welding Parameters on the Weld Pool Dimensions and Shape in a TIG Configuration
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Marine Stadler
2017-04-01
Full Text Available The weld pool shape created by the plasma arc interaction on a workpiece depends on many geometrical and physical parameters and on the operating conditions. Theoretical models are developed in such a way as to predict and to characterize the material. However, these models first need to be validated. Experimental results are hence proposed with parametric studies. Nevertheless, the interaction time is often short and the weld pool shape evolution not presented. In this work, the experimental setup and the diagnostic methods characterizing the workpiece are presented. The weld pool shape was evaluated versus time according to several parameters such as the current intensity value, the distance between the two electrodes, the cathode tip angle or the plasma gas nature. The results show that the depth-to-width ratio alone is not enough to compare the impact of the parameters. The analysis points out the great influence of the current intensity on the increase of the width and depth compared to the influence of the value of the cathode tip angle. The rise of the arc length leads to an increase of the power through a higher arc voltage; nevertheless, for distances of three and five millimeters and a characteristic time of the welding process of one second, this parameter has a weak influence on the energy transferred. The use of helium leads to a bigger volume of the weld pool due to an increase of width and depth.
Ximen Ji Ye
2000-01-01
In the present paper, Gaussian optical property in the bi-potential electrostatic and the bell-shaped magnetic combined lens - a new theoretical model first proposed in electron optics - has been thoroughly studied. Meanwhile, based on electron optical canonical aberration theory, analytical formulas of third-order geometrical and first-order chromatic aberration coefficients and their computational results have first been derived for this bi-potential electrostatic and bell-shaped magnetic combined lens. It is to emphasized that this theoretical study can be used to estimate third-order geometric and first-order chromatic aberrations and to provide a theoretical criterion for numerical computation in a rotationally symmetric electromagnetic lens.
Geometric Toys in the Attic? A Corpus Analysis of Early Exposure to Geometric Shapes
Resnick, Ilyse; Verdine, Brian; Golinkoff, Roberta; Hirsh-Pasek, Kathy
2016-01-01
Preschoolers' experiences with shapes are important because geometry is foundational to aspects of mathematics and it is now part of the Common Core for school-readiness. Exposure to shapes also provides experiences that are key to developing spatial thinking more broadly. Yet achieving a strong conceptual understanding of geometric categories can…
Geometric Toys in the Attic? A Corpus Analysis of Early Exposure to Geometric Shapes
Resnick, Ilyse; Verdine, Brian; Golinkoff, Roberta; Hirsh-Pasek, Kathy
2016-01-01
Preschoolers' experiences with shapes are important because geometry is foundational to aspects of mathematics and it is now part of the Common Core for school-readiness. Exposure to shapes also provides experiences that are key to developing spatial thinking more broadly. Yet achieving a strong conceptual understanding of geometric categories can…
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Maher A.R. Sadiq Al-Baghdadi
2017-01-01
Full Text Available Proton Exchange membrane (PEM fuel cells are still undergoing intense development, and the combination of new and optimized materials, improved product development, novel architectures, more efficient transport processes, and design optimization and integration are expected to lead to major gains in performance, efficiency, durability, reliability, manufacturability and cost-effectiveness. PEM fuel cell assembly pressure is known to cause large strains in the cell components. All components compression occurs during the assembly process of the cell, but also during fuel cell operation due to membrane swelling when absorbs water and cell materials expansion due to heat generating in catalyst layers. Additionally, the repetitive channel-rib pattern of the bipolar plates results in a highly inhomogeneous compressive load, so that while large strains are produced under the rib, the region under the channels remains approximately at its initial uncompressed state. This leads to significant spatial variations in GDL thickness and porosity distributions, as well as in electrical and thermal bulk conductivities and contact resistances (both at the ribe-GDL and membrane-GDL interfaces. These changes affect the rates of mass, charge, and heat transport through the GDL, thus impacting fuel cell performance and lifetime. In this study, computational fluid dynamics (CFD model of a PEM fuel cell has been developed to simulate the pressure distribution inside the cell, which are occurring during fuel cell assembly (bolt assembling, and membrane swelling and cell materials expansion during fuel cell running due to the changes of temperature and relative humidity. The PEM fuel cell model simulated includes the following components; two bi-polar plates, two GDLs, and, an MEA (membrane plus two CLs. This model is used to study and analyse the effect of channel geometrical configuration on the mechanical behaviour of the PEM fuel cell components. The analysis
Young Children's Developing Understanding of Geometric Shapes.
Hannibal, Mary Anne
1999-01-01
Presents research findings and suggestions on how children learn to categorize shapes. Discusses specific ways to present developmentally appropriate activities designed to enhance children's understanding of basic shapes. Contains 12 references. (ASK)
Diabil, Hayder Azeez; Li, Xin Kai; Abdalla, Ibrahim Elrayah
2017-09-01
Large-scale organized motions (commonly referred to coherent structures) and flow topology of a transitional separated-reattached flow have been visualised and investigated using flow visualisation techniques. Two geometrical shapes including two-dimensional flat plate with rectangular leading edge and three-dimensional square cylinder are chosen to shed a light on the flow topology and present coherent structures of the flow over these shapes. For both geometries and in the early stage of the transition, two-dimensional Kelvin-Helmholtz rolls are formed downstream of the leading edge. They are observed to be twisting around the square cylinder while they stay flat in the case of the two-dimensional flat plate. For both geometrical shapes, the two-dimensional Kelvin-Helmholtz rolls move downstream of the leading edge and they are subjected to distortion to form three-dimensional hairpin structures. The flow topology in the flat plate is different from that in the square cylinder. For the flat plate, there is a merging process by a pairing of the Kelvin-Helmholtz rolls to form a large structure that breaks down directly into many hairpin structures. For the squire cylinder case, the Kelvin-Helmholtz roll evolves topologically to form a hairpin structure. In the squire cylinder case, the reattachment length is much shorter and a forming of the three-dimensional structures is closer to the leading edge than that in the flat plate case.
Geometrical Shape Investigation For Electrodes in Silent Discharge Chamber
Facta, Mochammad; Ayu Ketut Umiati, Ngurah; Warsito, Agung
2017-04-01
Silent discharge is the most prominent method to carry out plasma reaction because. discharge is easily initiated by injecting alternating current in high voltage to the pair of separated electrodes. The electron emission from surface of dielectric placed on instantaneous cathode is stimulated by ion induced electron emission. In this method, spark is avoided by placing insulation material to either one or both of the electrodes. In practical, it is very difficult to determine the exact limit of the voltage that initiate the discharge by mathematical analysis because it depends on many factors, namely dimensions, type and geometrical shapes of electrode, thickness of insulation, and type of electric field inside the discharge gap. To get lower initial voltage for discharge, it is important to find the best geometrical shape of electrode in relation to skin effect that trigger electron emission. This work investigates the behaviour of charges, current, electric field and voltage surrounding electrodes with various geometrical shape.
Ishimoto, Yukitaka
2014-01-01
In order to describe two-dimensionally packed cells in epithelial tissues both mathematically and physically, there have been developed several sorts of geometrical models, such as the vertex model, the finite element model, the cell-centered model, the cellular Potts model. So far, in any case, pressures have not neatly been dealt with and curvatures of the cell boundaries have been even omitted through their approximations. We focus on these quantities and formulate them on the vertex model. Thus, a model with the curvatures is constructed and its algorithm is given for simulation. Its possible extensions and applications will also be discussed.
Nemati, Farshad
2009-01-01
Over the past few decades, different theories have been advanced to explain geometric-optical illusions based on various perceptual processes such as assimilation and/or contrast. Consistent with the contradictory effects of assimilation and contrast, Pressey's assimilation theory provided an explanation for the Müller-Lyer illusion, but failed to account for the Titchener (Ebbinghaus) illusion. A model that explains both Müller-Lyer and Titchener illusions according to a common underlying process may outline a unified explanation for a variety of geometric-optical illusions. In order to develop such a model, the concept of empty space is introduced as an area of the illusory figure that is not filled by line drawings. It was predicted that the magnitude of illusion would increase with the area of the empty space around the illusory figures. The effect of empty space on the magnitude of perceptual distortion was measured in Müller-Lyer figures, with outward arrowheads of different length. The results indicated an overestimation of the target stimulus in all of the figures. Nevertheless, consistent with the prediction of the present model, the horizontal line in the Müller-Lyer figure with the longest arrowheads appeared shorter than that with the shortest arrowheads, although the size contrast of these figures was the same. According to the analysis proposed in the present study, the area of empty space not only affects the magnitude of illusion but also serves as a contextual cue for the perceptual system to determine the direction of illusion (orientation). The functional relationships between the size contrast and empty space provide a common explanation for the Müller-Lyer, Titchener, and a variety of other geometric-optical illusions.
Windhager, Sonja; Schaefer, Katrin; Fink, Bernhard
2011-01-01
Evolutionary psychologists claim that women have adaptive preferences for specific male physical traits. Physical strength may be one of those traits, because recent research suggests that women rate faces of physically strong men as more masculine, dominant, and attractive. Yet, previous research has been limited in its ability to statistically map specific male facial shapes and features to corresponding physical measures (e.g., strength) and ratings (e.g., attractiveness). The association of handgrip strength (together with measures of shoulder width, body height, and body fat) and women's ratings of male faces (concerning dominance, masculinity, and attractiveness) were studied in a sample of 26 Caucasian men (aged 18-32 years). Geometric morphometrics was used to statistically assess the covariation of male facial shape with these measures. Statistical results were visualized with thin-plate spline deformation grids along with image unwarping and image averaging. Handgrip strength together with shoulder width, body fat, dominance, and masculinity loaded positively on the first dimension of covariation with facial shape (explaining 72.6%, P attractive and taller men had longer, narrower jaws and wider/fuller lips. Male physical strength was more strongly associated with changes in face shape that relate to perceived masculinity and dominance than to attractiveness. Our study adds to the growing evidence that attractiveness and dominance/masculinity may reflect different aspects of male mate quality. Copyright © 2011 Wiley-Liss, Inc.
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I. I. Kravchenko
2016-01-01
Full Text Available There is a variety of objectives for measuring deviations of flatness, size and mutual arrangement of flat surfaces, namely: processing accuracy control, machinery condition monitoring, treatment process control in terms of shape deviation, comparative analysis of machine rigidity. If for a processing accuracy control it is sufficient to obtain the flatness deviation, as the maximum adjoining surface deviation, the choice of the adjoining surface as a zero reference datum deviation leads to considerable difficulties in creating devices and in particular devices for measuring size and shape variations. The flat surface is characterized by mutual arrangement of its points and can be represented by equation in the selected coordinate system. The objective of this work is to provide analytical construction of the vector field F, which describes the real surface with an appropriate approximation upon modelling the face milling of the flat surfaces of body parts in conditions of anisotropic rigidity of technological system. To determine the numerical value of shape and size deviation characteristics the average surfaces can serve a basis for the zero reference values of vectors. A mean value theorem allows to obtain measurement information about deviations in shape, size and arrangement of processed flat surfaces in terms of metrology, as well as about the process parameters such as depth of cut, feed, cutting speed, anisotropic rigidity of technological system that characterize the specific processing conditions. The machining center MS 12-250 was used to carry out a number of experiments with processing the surfaces of the prism-shaped body parts (300x300x250 and the subsequent measurements of flatness on the IS-49 optical line to prove the correlation between expected and observed values of the vectors of flatness deviations.
Geometric Methods for ATR: Shape Spaces, Metrics, Object/Image Relations, and Shapelets
2007-09-30
been collaborating with Ms. Olga Mendoza, a young researcher at AFRL, Wright -Patterson AFB, who has performed additional tests of the algorithms, and... modulo the action of a certain group of transformations on Rn , n = 2,3, and give global coordinates on the shape space, (2) give necessary and...r points in R" modulo the action of the group of affine transformations. These spaces would then represent the distinct objects and images independent
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C.C. Cabuga
2017-09-01
Full Text Available Pomacea caniculata or Golden Apple Snail (GAS existed to be a rice pest in the Philippines and in Asia. Likewise, geographic location also contributes its increasing populations thus making it invasive among freshwater habitats and rice field areas. This study was conducted in order to describe shell shape variations and sexual dimorphism among the populations of P. caniculata. A total of 180 were randomly collected in the three lakes of Esperanza, Agusan del Sur (Lake Dakong Napo, Lake Oro, and Lake Cebulan, of which each lake comprised of 60 samples (30 males and 30 females. To determine the variations and sexual dimorphism in the shell shape of golden apple snail, coordinates was administered to relative warp analysis and the resulting data were subjected to Multivariate Analysis of Variance (MANOVA, Principal Component Analysis (PCA and Canonical Variate Analysis (CVA. The results show statistically significant (P<0.05 from the appended male and female dorsal and ventral/apertural portion. While male and female spire height, body size, and shell shape opening also shows significant variations. These phenotypic distinctions could be associated with geographic isolation, predation and nutrient component of the gastropods. Thus, the importance of using geometric morphometric advances in describing sexual dimorphism in the shell shape of P. caniculata.
Gómez-Robles, Aida; Martinón-Torres, María; Bermúdez de Castro, José María; Prado-Simón, Leyre; Arsuaga, Juan Luis
2011-12-01
This paper continues the series of articles initiated in 2006 that analyse hominin dental crown morphology by means of geometric morphometric techniques. The detailed study of both upper premolar occlusal morphologies in a comprehensive sample of hominin fossils, including those coming from the Gran Dolina-TD6 and Sima de los Huesos sites from Atapuerca, Spain, complement previous works on lower first and second premolars and upper first molars. A morphological gradient consisting of the change from asymmetric to symmetric upper premolars and a marked reduction of the lingual cusp in recent Homo species has been observed in both premolars. Although percentages of correct classification based on upper premolar morphologies are not very high, significant morphological differences between Neanderthals (and European middle Pleistocene fossils) and modern humans have been identified, especially in upper second premolars. The study of morphological integration between premolar morphologies reveals significant correlations that are weaker between upper premolars than between lower ones and significant correlations between antagonists. These results have important implications for understanding the genetic and functional factors underlying dental phenotypic variation and covariation. Copyright Â© 2011 Elsevier Ltd. All rights reserved.
Smith, Amanda L; Benazzi, Stefano; Ledogar, Justin A; Tamvada, Kelli; Pryor Smith, Leslie C; Weber, Gerhard W; Spencer, Mark A; Dechow, Paul C; Grosse, Ian R; Ross, Callum F; Richmond, Brian G; Wright, Barth W; Wang, Qian; Byron, Craig; Slice, Dennis E; Strait, David S
2015-01-01
In a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. However, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered from only one or a few individuals. This results in a lack of knowledge concerning the mechanical significance of intraspecific shape variation that limits our ability to infer the significance of interspecific differences. This study uses geometric morphometric methods (GM) and finite element analysis (FEA) to examine the biomechanical implications of shape variation in chimpanzee crania, thereby providing a comparative context in which to interpret shape-related mechanical variation between hominin species. Six finite element models (FEMs) of chimpanzee crania were constructed from CT scans following shape-space Principal Component Analysis (PCA) of a matrix of 709 Procrustes coordinates (digitized onto 21 specimens) to identify the individuals at the extremes of the first three principal components. The FEMs were assigned the material properties of bone and were loaded and constrained to simulate maximal bites on the P(3) and M(2) . Resulting strains indicate that intraspecific cranial variation in morphology is associated with quantitatively high levels of variation in strain magnitudes, but qualitatively little variation in the distribution of strain concentrations. Thus, interspecific comparisons should include considerations of the spatial patterning of strains rather than focus only on their magnitudes. © 2014 Wiley Periodicals, Inc.
Mori, Taizo; Hegmann, Torsten
2016-10-01
Size, shape, overall composition, and surface functionality largely determine the properties and applications of metal nanoparticles. Aside from well-defined metal clusters, their composition is often estimated assuming a quasi-spherical shape of the nanoparticle core. With decreasing diameter of the assumed circumscribed sphere, particularly in the range of only a few nanometers, the estimated nanoparticle composition increasingly deviates from the real composition, leading to significant discrepancies between anticipated and experimentally observed composition, properties, and characteristics. We here assembled a compendium of tables, models, and equations for thiol-protected gold nanoparticles that will allow experimental scientists to more accurately estimate the composition of their gold nanoparticles using TEM image analysis data. The estimates obtained from following the routines described here will then serve as a guide for further analytical characterization of as-synthesized gold nanoparticles by other bulk (thermal, structural, chemical, and compositional) and surface characterization techniques. While the tables, models, and equations are dedicated to gold nanoparticles, the composition of other metal nanoparticle cores with face-centered cubic lattices can easily be estimated simply by substituting the value for the radius of the metal atom of interest.
Dhakal, Subas; Solis, Francisco J.; Olvera de la Cruz, Monica
2012-07-01
Recent experiments have shown that defect conformations in spherical nematic liquid crystals can be controlled through variations of temperature, shell thickness, and other environmental parameters. These modifications can be understood as a result of the induced changes in the effective elastic constants of the system. To characterize the relation between defect conformations and elastic anisotropy, we carry out Monte Carlo simulations of a nematic on a spherical surface. As the anisotropy is increased, the defects flow from a tetrahedral arrangement to two coalescing pairs and then to a great circle configuration. We also analyze this flow using a variational method based on harmonic configurations.
Werneburg, Ingmar; Wilson, Laura A B; Parr, William C H; Joyce, Walter G
2015-03-01
The unique ability of modern turtles to retract their head and neck into the shell through a side-necked (pleurodiran) or hidden-necked (cryptodiran) motion is thought to have evolved independently in crown turtles. The anatomical changes that led to the vertebral shapes of modern turtles, however, are still poorly understood. Here we present comprehensive geometric morphometric analyses that trace turtle vertebral evolution and reconstruct disparity across phylogeny. Disparity of vertebral shape was high at the dawn of turtle evolution and decreased after the modern groups evolved, reflecting a stabilization of morphotypes that correspond to the two retraction modes. Stem turtles, which had a very simple mode of retraction, the lateral head tuck, show increasing flexibility of the neck through evolution towards a pleurodiran-like morphotype. The latter was the precondition for evolving pleurodiran and cryptodiran vertebrae. There is no correlation between the construction of formed articulations in the cervical centra and neck mobility. An increasing mobility between vertebrae, associated with changes in vertebral shape, resulted in a more advanced ability to retract the neck. In this regard, we hypothesize that the lateral tucking retraction of stem turtles was not only the precondition for pleurodiran but also of cryptodiran retraction. For the former, a kink in the middle third of the neck needed to be acquired, whereas for the latter modification was necessary between the eighth cervical vertebra and first thoracic vertebra. Our paper highlights the utility of 3D shape data, analyzed in a phylogenetic framework, to examine the magnitude and mode of evolutionary modifications to vertebral morphology. By reconstructing and visualizing ancestral anatomical shapes, we provide insight into the anatomical features underlying neck retraction mode, which is a salient component of extant turtle classification. © The Author(s) 2014. Published by Oxford University Press
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Khalaf A. M.
2014-01-01
Full Text Available The critical points of potential energy surface (PES’s of the limits of nuclear struc- ture harmonic oscillator, axially symmetric rotor and deformed -soft and discussed in framework of the general geometric collective model (GCM. Also the shape phase transitions linking the three dynamical symmetries are studied taking into account only three parameters in the PES’s. The model is tested for the case of 238 92 U , which shows a more prolate behavior. The optimized model parameters have been adjusted by fit- ting procedure using a simulated search program in order to reproduce the experimental excitation energies in the ground state band up to 6 + and the two neutron separation energies.
The geometric effect and programming current reduction in cylindrical-shaped phase change memory
Li, Yiming; Hwang, Chih-Hong; Li, Tien-Yeh; Cheng, Hui-Wen
2009-07-01
This study conducts a three-dimensional electro-thermal time-domain simulation for numerical analysis of cylindrical-shaped phase change memories (PCMs). The influence of chalcogenide material, germanium antimony telluride (GeSbTe or GST), structure on PCM operation is explored. GST with vertical structure exhibits promising characteristics. The bottom electrode contact (BEC) is advanced to improve the operation of PCMs, where a 25% reduction of the required programming current is achieved at a cost of 26% reduced resistance ratio. The position of the BEC is then shifted to further improve the performance of PCMs. The required programming current is reduced by a factor of 11, where the resistance ratio is only decreased by 6.9%. However, the PCMs with a larger shift of BEC are sensitive to process variation. To design PCMs with less than 10% programming current variation, PCMs with shifted BEC, where the shifted distance is equal to 1.5 times the BEC's radius, is worth considering. This study quantitatively estimates the structure effect on the phase transition of PCMs and physically provides an insight into the design and technology of PCMs.
Krieger, Jonathan D.
2014-01-01
• Premise of the study: I present a protocol for creating geometric leaf shape metrics to facilitate widespread application of geometric morphometric methods to leaf shape measurement. • Methods and Results: To quantify circularity, I created a novel shape metric in the form of the vector between a circle and a line, termed geometric circularity. Using leaves from 17 fern taxa, I performed a coordinate-point eigenshape analysis to empirically identify patterns of shape covariation. I then compared the geometric circularity metric to the empirically derived shape space and the standard metric, circularity shape factor. • Conclusions: The geometric circularity metric was consistent with empirical patterns of shape covariation and appeared more biologically meaningful than the standard approach, the circularity shape factor. The protocol described here has the potential to make geometric morphometrics more accessible to plant biologists by generalizing the approach to developing synthetic shape metrics based on classic, qualitative shape descriptors. PMID:25202647
Cosmological parameters from large scale structure - geometric versus shape information
Hamann, Jan; Lesgourgues, Julien; Rampf, Cornelius; Wong, Yvonne Y Y
2010-01-01
The matter power spectrum as derived from large scale structure (LSS) surveys contains two important and distinct pieces of information: an overall smooth shape and the imprint of baryon acoustic oscillations (BAO). We investigate the separate impact of these two types of information on cosmological parameter estimation, and show that for the simplest cosmological models, the broad-band shape information currently contained in the SDSS DR7 halo power spectrum (HPS) is by far superseded by geometric information derived from the baryonic features. An immediate corollary is that contrary to popular beliefs, the upper limit on the neutrino mass m_\
Talaghat, Mohammad Reza; Jokar, Seyyed Mohammad
2017-06-01
This article offers a study on estimation of heat transfer parameters (coefficient and thermal diffusivity) using analytical solutions and experimental data for regular geometric shapes (such as infinite slab, infinite cylinder, and sphere). Analytical solutions have a broad use in experimentally determining these parameters. Here, the method of Finite Integral Transform (FIT) was used for solutions of governing differential equations. The temperature change at centerline location of regular shapes was recorded to determine both the thermal diffusivity and heat transfer coefficient. Aluminum and brass were used for testing. Experiments were performed for different conditions such as in a highly agitated water medium (T = 52 °C) and in air medium (T = 25 °C). Then, with the known slope of the temperature ratio vs. time curve and thickness of slab or radius of the cylindrical or spherical materials, thermal diffusivity value and heat transfer coefficient may be determined. According to the method presented in this study, the estimated of thermal diffusivity of aluminum and brass is 8.395 × 10-5 and 3.42 × 10-5 for a slab, 8.367 × 10-5 and 3.41 × 10-5 for a cylindrical rod and 8.385 × 10-5 and 3.40 × 10-5 m2/s for a spherical shape, respectively. The results showed there is close agreement between the values estimated here and those already published in the literature. The TAAD% is 0.42 and 0.39 for thermal diffusivity of aluminum and brass, respectively.
Passive morphing of flying wing aircraft: Z-shaped configuration
Mardanpour, Pezhman; Hodges, Dewey H.
2014-01-01
High Altitude, Long Endurance (HALE) aircraft can achieve sustained, uninterrupted flight time if they use solar power. Wing morphing of solar powered HALE aircraft can significantly increase solar energy absorbency. An example of the kind of morphing considered in this paper requires the wings to fold so as to orient a solar panel to be hit more directly by the sun's rays at specific times of the day. An example of the kind of morphing considered in this paper requires the wings to fold so as to orient a solar panel that increases the absorption of solar energy by decreasing the angle of incidence of the solar radiation at specific times of the day. In this paper solar powered HALE flying wing aircraft are modeled with three beams with lockable hinge connections. Such aircraft are shown to be capable of morphing passively, following the sun by means of aerodynamic forces and engine thrusts. The analysis underlying NATASHA (Nonlinear Aeroelastic Trim And Stability of HALE Aircraft), a computer program that is based on geometrically exact, fully intrinsic beam equations and a finite-state induced flow model, was extended to include the ability to simulate morphing of the aircraft into a "Z" configuration. Because of the "long endurance" feature of HALE aircraft, such morphing needs to be done without relying on actuators and at as near zero energy cost as possible. The emphasis of this study is to substantially demonstrate the processes required to passively morph a flying wing into a Z-shaped configuration and back again.
FMRI evidence of 'mirror' responses to geometric shapes.
Directory of Open Access Journals (Sweden)
Clare Press
Full Text Available Mirror neurons may be a genetic adaptation for social interaction. Alternatively, the associative hypothesis proposes that the development of mirror neurons is driven by sensorimotor learning, and that, given suitable experience, mirror neurons will respond to any stimulus. This hypothesis was tested using fMRI adaptation to index populations of cells with mirror properties. After sensorimotor training, where geometric shapes were paired with hand actions, BOLD response was measured while human participants experienced runs of events in which shape observation alternated with action execution or observation. Adaptation from shapes to action execution, and critically, observation, occurred in ventral premotor cortex (PMv and inferior parietal lobule (IPL. Adaptation from shapes to execution indicates that neuronal populations responding to the shapes had motor properties, while adaptation to observation demonstrates that these populations had mirror properties. These results indicate that sensorimotor training induced populations of cells with mirror properties in PMv and IPL to respond to the observation of arbitrary shapes. They suggest that the mirror system has not been shaped by evolution to respond in a mirror fashion to biological actions; instead, its development is mediated by stimulus-general processes of learning within a system adapted for visuomotor control.
Natalis, Laurent C; Wesselingh, Renate A
2013-06-01
To shed light on the role played by pollinators in the diversification of angiosperms, focus is needed on how floral isolation varies locally in the early stages of plant divergence. The few studies performed so far have often used species pairs with distinct pollination syndromes and contrasting floral displays. Here, we focus on a hybridizing pair (Rhinanthus minor and Rhinanthus angustifolius) with strong similarities in flower morphology and pollinators (bumblebees). We examined how ethological isolation changes locally in relation to relative Rhinanthus frequencies, spatial configurations, and pollinator assemblages. Interestingly, floral divergence based on adaptation to different pollinators is unlikely in Rhinanthus: no relationship was found between floral isolation and the local pollinator assemblage. In contrast, species frequency and spatial arrangement strongly influenced bumblebee behavior, ethological isolation, and thus potentially hybrid formation. When both Rhinanthus were present in equal proportions, bees generally preferred the more rewarding and conspicuous species. However, when the Rhinanthus frequencies were unbalanced, the more abundant species was preferred, although this was less pronounced when the less rewarding R. minor predominated. Ethological isolation is highly sensitive to site characteristics, and can be as high as in species with contrasting floral displays and pollinator suites, even though flowers are similar. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.
Directory of Open Access Journals (Sweden)
Pirinen Pekka
2006-01-01
Full Text Available Generic ultra-wideband (UWB spread-spectrum system performance is evaluated in centralized and distributed spatial topologies comprising square-shaped indoor cells. Statistical distributions for link distances in single-cell and multicell configurations are derived. Cochannel-interference-induced outage probability is used as a performance measure. The probability of outage varies depending on the spatial distribution statistics of users (link distances, propagation characteristics, user activities, and receiver settings. Lognormal fading in each channel path is incorporated in the model, where power sums of multiple lognormal signal components are approximated by a Fenton-Wilkinson approach. Outage performance of different spatial configurations is outlined numerically. Numerical results show the strong dependence of outage probability on the link distance distributions, number of rake fingers, and path losses.
EFFECT OF GEOMETRIC CONFIGURATIONS ON HYDRODYNAMIC PERFORMANCE ASSESSMENT OF A MARINE PROPELLER
Directory of Open Access Journals (Sweden)
Samir. E. Belhenniche
2016-12-01
Full Text Available The present paper deals with the effect of the geometric characteristics on the propeller hydrodynamic performances. Several propeller configurations are created by changing number of blades, expanded area and pitch ratios. The Reynolds-Averaged Navier-Stokes (RANS equations are solved using the commercial code FLUENT 6.3.26. The standard
Dietary fatty acid type alters atherosclerotic lesion progression and macrophage lipid accumulation. Incompletely elucidated are the mechanisms by which fatty acids differing in double-bond geometric or positional configuration alter arterial lipid accumulation. The objective of this study was to ev...
Greathouse, James S.; Schwing, Alan M.
2015-01-01
This paper explores use of computational fluid dynamics to study the e?ect of geometric porosity on static stability and drag for NASA's Multi-Purpose Crew Vehicle main parachute. Both of these aerodynamic characteristics are of interest to in parachute design, and computational methods promise designers the ability to perform detailed parametric studies and other design iterations with a level of control previously unobtainable using ground or flight testing. The approach presented here uses a canopy structural analysis code to define the inflated parachute shapes on which structured computational grids are generated. These grids are used by the computational fluid dynamics code OVERFLOW and are modeled as rigid, impermeable bodies for this analysis. Comparisons to Apollo drop test data is shown as preliminary validation of the technique. Results include several parametric sweeps through design variables in order to better understand the trade between static stability and drag. Finally, designs that maximize static stability with a minimal loss in drag are suggested for further study in subscale ground and flight testing.
A Study Regarding the Spontaneous Use of Geometric Shapes in Young Children's Drawings
Villarroel, José Domingo; Sanz Ortega, Olga
2017-01-01
The studies regarding how the comprehension of geometric shapes evolves in childhood are largely based on the assessment of children's responses during the course of tasks linked to the recognition, classification or explanation of prototypes and models. Little attention has been granted to the issue as to what extent the geometric shape turns out…
2009-01-01
Applied Analysis, vol. 2007, Article ID 45153, 14 pages, 2007. doi:10.1155/2007/45153 113 [47] Marc Vaillant and Joan Glauns, “Surface matching via...Adaptive manifold learning. NIPS, 2004. [70] J. Costa , A. Girotra and A.O. Hero, Estimating local intrinsic dimension with k- nearest neighbor
Variations of Shape in Industrial Geometric Models
Veelo, Bastiaan Niels
2004-01-01
This thesis presents an approach to free-form surface manipulations, which conceptually improves an existing CAD system that constructs surfaces by smoothly interpolating a network of intersecting curves. There are no regularity requirements on the network, which already yields superior modelling capabilities compared to systems that are based on industry-standard NURBS surfaces. Originally, the shape of such a surface can be modified only locally by manipulating a curve in the network. In t...
Lee, Sang-Moon; Kim, Kwang-Yong
2013-07-01
Comparative study has been performed with various channel cross-sectional shapes and channel configurations of a zigzag printed circuit heat exchanger (PCHE), which has been considered as a heat exchanging device for the gas turbine based generation systems. Three-dimensional Reynolds-averaged Navier-Stokes equations and heat transfer equations are solved to analyze conjugate heat transfer in the zigzag channels. The shear stress transport model with a low Reynolds number wall treatment is used as a turbulence closure. The global Nusselt number, Colburn j-factor, effectiveness, and friction factor are used to estimate the thermal-hydraulic performance of the PCHE. Four different shapes of channel cross section (semicircular, rectangular, trapezoidal, and circular) and four different channel configurations are tested to determine their effects on thermal-hydraulic performance. The rectangular channel shows the best thermal performance but the worst hydraulic performance, while the circular channel shows the worst thermal performance. The Colburn j-factor and friction factor are found to be inversely proportional to the Reynolds number in cold channels, while the effectiveness and global Nusselt number are proportional to the Reynolds number.
Iso-geometric shape optimization of magnetic density separators
DEFF Research Database (Denmark)
Dang Manh, Nguyen; Evgrafov, Anton; Gravesen, Jens;
2014-01-01
Purpose The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly...... covers with B-splines and defines a cost functional that measures the non-uniformity of the magnetic field in an area above the poles. The authors apply an iso-geometric shape optimization procedure, which allows us to accurately represent, analyze and optimize the geometry using only a few design...... variables. The design problem is regularized by imposing constraints that enforce the convexity of the pole cover shapes and is solved by a non-linear optimization procedure. The paper validates the implementation of the algorithm using a simplified variant of the design problem with a known analytical...
Defying geometric similarity: Shape centralization in male UK offshore workers.
Stewart, Arthur D; Ledingham, Robert J; Furnace, Graham; Williams, Hector; Nevill, Alan M
2017-05-06
Applying geometric similarity predictions of body dimensions to specific occupational groups has the potential to reveal useful ergonomic and health implications. This study assessed a representative sample of the male UK offshore workforce, and examined how body dimensions from sites typifying musculoskeletal development or fat accumulation, differed from predicted values. A cross sectional sample was obtained across seven weight categories using quota sampling, to match the wider workforce. In total, 588 UK offshore workers, 84 from each of seven weight categories, were measured for stature, mass and underwent 3D body scans which yielded 22 dimensional measurements. Each measurement was modeled using a body-mass power law (adjusting for age), to derive its exponent, which was compared against that predicted from geometric similarity. Mass scaled to stature (1.73) (CI: 1.44-2.02). Arm and leg volume increased by mass(0.8) , and torso volume increased by mass(1.1) in contrast to mass (1.0) predicted by geometric similarity. Neck girth increased by mass (0.33) as expected, while torso girth and depth dimensions increased by mass(0.53-0.72) , all substantially greater than assumed by geometric similarity. After controlling for age, offshore workers experience spectacular "super-centralization" of body shape, with greatest gains in abdominal depth and girth dimensions in areas of fat accumulation, and relative dimensional loss in limbs. These findings are consistent with the antecedents of sarcopenic obesity, and should be flagged as a health concern for this workforce, and for future targeted research and lifestyle interventions. © 2016 Wiley Periodicals, Inc.
Geometric plane shapes for computer-generated holographic engraving codes
Augier, Ángel G.; Rabal, Héctor; Sánchez, Raúl B.
2017-04-01
We report a new theoretical and experimental study on hologravures, as holographic computer-generated laser-engravings. A geometric theory of images based on the general principles of light ray behaviour is shown. The models used are also applicable for similar engravings obtained by any non-laser method, and the solutions allow for the analysis of particular situations, not only in the case of light reflection mode, but also in transmission mode geometry. This approach is a novel perspective allowing the three-dimensional (3D) design of engraved images for specific ends. We prove theoretically that plane curves of very general geometric shapes can be used to encode image information onto a two-dimensional (2D) engraving, showing notable influence on the behaviour of reconstructed images that appears as an exciting investigation topic, extending its applications. Several cases of code using particular curvilinear shapes are experimentally studied. The computer-generated objects are coded by using the chosen curve type, and engraved by a laser on a plane surface of suitable material. All images are recovered optically by adequate illumination. The pseudoscopic or orthoscopic character of these images is considered, and an appropriate interpretation is presented.
Keresztenyi, Zoltan; Cesari, Paola; Fazekas, Gabor; Laczko, Jozsef
2009-01-01
Variances of drawing arm movements between patients with Parkinson's disease and healthy controls were compared. The aim was to determine whether differences in joint synergies or individual joint rotations affect the endpoint (hand position) variance. Joint and endpoint coordinates were measured while participants performed drawing tasks.…
Yamashita, Osamu; Tomiyoshi, Shoichi
2002-10-01
The cooling temperatures of rectangular parallelepiped Bi and Bi0.88Sb0.12 polycrystals of various dimensions were measured at 298 K as a function of electric current in magnetic fields up to 2.17 T, where the magnetic field was aligned along the thickness (t) direction of the sample and copper current leads were soldered to the centers of two ridges along the thickness direction on two diagonally opposite corners of a rectangle with length L and width W. With this configuration, the temperature measurements were carried out at both end surfaces with the cross section (W×t). The thermoelement was not in contact with a heat sink. The maximum cooling temperature at the cooled surface increases with increasing magnetic field, but it depends strongly on not only the aspect ratio of the sample but also its thickness. It was found that geometrically optimum shaping of a thermoelement is very important for achieving high-cooling efficiency. A thermoelement made of Bi0.88Sb0.12 with optimum dimensions of L=15 mm, W=2 mm, and t=3 mm effects the high-cooling temperature of 4.2 K in a magnetic field of 2.17 T. As a result, the cooling temperature reached 74% of the cooling temperature of 5.7 K obtained with p-type Bi2Te3 of L=12 mm and W=t=4.8 mm which has a thermoelectric figure of merit of ZT=0.87 at 298 K.
Fechte-Heinen, R.; Schlömerkemper, A.
2016-11-01
This work is concerned with different estimates of the quasiconvexification of multi-well energy landscapes of NiTi shape memory alloys, which models the overall behavior of the material. Within the setting of the geometrically linear theory of elasticity, we consider a formula of the quasiconvexification which involves the so-called energy of mixing.We are interested in lower and upper bounds on the energy of mixing in order to get a better understanding of the quasiconvexification. The lower bound on the energy of mixing is obtained by convexification; it is also called Sachs or Reuß lower bound. The upper bound on the energy of mixing is based on second-order lamination. In particular, we are interested in the difference between the lower and upper bounds. Our numerical simulations show that the difference is in fact of the order of 1% and less in martensitic NiTi, even though both bounds on the energy of mixing were rather expected to differ more significantly. Hence, in various circumstances it may be justified to simply work with the convexification of the multi-well energy, which is relatively easy to deal with, or with the lamination upper bound, which always corresponds to a physically realistic microstructure, as an estimate of the quasiconvexification. In order to obtain a potentially large difference between upper and lower bound, we consider the bounds along paths in strain space which involve incompatible strains. In monoclinic shape memory alloys, three-tuples of pairwise incompatible strains play a special role since they form so-called T 3-configurations, originally discussed in a stress-free setting. In this work, we therefore consider in particular numerical simulations along paths in strain space which are related to these T 3-configurations. Interestingly, we observe that the second-order lamination upper bound along such paths is related to the geometry of the T 3-configurations. In addition to the purely martensitic regime, we also consider
Performance of cylindrical-conical cyclones with different geometrical configurations
Directory of Open Access Journals (Sweden)
J.D.A.M. Santana
2001-09-01
Full Text Available The present work is a continuation of a study of the influence of geometric characteristics on the performance of reverse-flow cylindrical-conical cyclones. After studying the behavior of the pressure drop in previous work (Arnosti et al., 1998, here performance in terms of collection efficiency in the removal of particulate material is addressed. The independent variables considered in this study were inlet gas velocity (three velocities and the following dimensions of the cyclone: the cylindrical section (three heights and internal height of the gas exit duct (three heights. The tests were performed using an 3³ experimental design. Analysis of the results for overall efficiency was carried out using response surfaces and the statistical parameters were estimated from linear regression.
Ecolifter Conceptual Configuration Design and Parameter Analysis
Institute of Scientific and Technical Information of China (English)
唐胜景
2003-01-01
In the phase of conceptually designing, the Ecolifter with three-lift-surface configuration, the influences of aircraft geometric parameters and configuration such as wing geometric parameters, canard parameters, aircraft center of gravity and engine positions and so on, on flight dynamic stability are discussed with the integrated analysis method. On the basis of the analysis of flight dynamic stability, the suitable wing geometric parameters are given and the improved aircraft configuration is proposed.
La Marca, Floriana; Moroni, Monica; Cherubini, Lorenzo; Lupo, Emanuela; Cenedese, Antonio
2012-07-01
The recovery of high-quality plastic materials is becoming an increasingly challenging issue for the recycling sector. Technologies for plastic recycling have to guarantee high-quality secondary raw material, complying with specific standards, for use in industrial applications. The variability in waste plastics does not always correspond to evident differences in physical characteristics, making traditional methodologies ineffective for plastic separation. The Multidune separator is a hydraulic channel allowing the sorting of solid particles on the basis of differential transport mechanisms by generating particular fluid dynamic conditions due to its geometric configuration and operational settings. In this paper, the fluid dynamic conditions were investigated by an image analysis technique, allowing the reconstruction of velocity fields generated inside the Multidune, considering two different geometric configurations of the device, Configuration A and Configuration B. Furthermore, tests on mono- and bi-material samples were completed with varying operational conditions under both configurations. In both series of experiments, the bi-material samples were composed of differing proportions (85% vs. 15%) to simulate real conditions in an industrial plant for the purifying of a useful fraction from a contaminating fraction. The separation results were evaluated in terms of grade and recovery of the useful fraction.
Energy Technology Data Exchange (ETDEWEB)
Badrianto, Muldani Dwi; Riupassa, Robi D.; Basar, Khairul, E-mail: khbasar@fi.itb.ac.id [Nuclear Physics and Biophysics Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung (Indonesia)
2015-09-30
Nuclear batteries have strategic applications and very high economic potential. One Important problem in application of nuclear betavoltaic battery is its low efficiency. Current efficiency of betavoltaic nuclear battery reaches only arround 2%. One aspect that can influence the efficiency of betavoltaic nuclear battery is the geometrical configuration of radioactive source. In this study we discuss the effect of geometrical configuration of radioactive source material to the radiation intensity in betavoltaic nuclear battery system. received by the detector. By obtaining the optimum configurations, the optimum usage of radioactive materials can be determined. Various geometrical configurations of radioactive source material are simulated. It is obtained that usage of radioactive source will be optimum for circular configuration.
Hong, Cheolpyo; Lee, Dong-Hoon; Han, Bong Soo
2014-07-01
Open-configuration magnetic resonance imaging (MRI) systems are becoming increasingly desirable for musculoskeletal imaging and image-guided radiotherapy because of their non-claustrophobic configuration. However, geometric image distortion in large fields-of-view (FOV) due to field inhomogeneity and gradient nonlinearity hinders the practical applications of open-type MRI. We demonstrated the use of geometric distortion correction for increasing FOV in open MRI. Geometric distortion was modeled and corrected as a global polynomial function. The appropriate polynomial order was identified as the minimum difference between the coordinates of control points in the distorted MR image space and those predicted by polynomial modeling. The sixth order polynomial function was found to give the optimal value for geometric distortion correction. The area of maximum distortion was<1 pixel with an FOV of 285mm. The correction performance error was increased at most 1.2% and 2.9% for FOVs of 340mm and~400mm compared with the FOV of 285mm. In particular, unresolved distortion was generated by local deformation near the gradient coil center. Copyright © 2014 Elsevier Inc. All rights reserved.
Identification of Geometric Shapes with Real-time Neural Networks
Directory of Open Access Journals (Sweden)
E. Castillejos-Villatoro
2016-08-01
Full Text Available This article presents the implementation of an identification system of geometric figures and their respective colors, this made with neural networks by using Back propagation control implementation. This paper describes the process of extracting characteristic patterns of images, with the help of Artificial Neural Networks. The information Neuronal Network along with additional data of images and colors, will be stored in a database which will be put dynamic that will evolve with the figures they will be learning this by implementing a PID created in MATLAB Software. Subsequent to perform image capture with an independent PC WEBCAM. This processes the image and along with the data acquired and processed by the neural network in the pattern of shapes and colors. For image processing libraries MATLAB be used both in the implementation of a system acquisition by WEBCAM.
Battisacco, E.; Franca, M. J.; Schleiss, A. J.
2016-11-01
Dams trap sediment in the upstream reservoir, which may lead to river bed armoring, streambank erosion and failure, channel incision and reduction of the morphological diversity in the downstream river reaches. The replenishment of sediment is a mitigation measure for this problem to be applied in river reaches downstream of dams. Previously performed field experiments always used one single volume of sediment replenishment. To explore different alternatives, the replenished volume was here divided in four deposits with the motivation to influence also the morphological evolution downstream. Six different geometrical configurations together with three submergence conditions of sediment replenishment were tested for the first time in a laboratory experiment and are herein discussed. The results of the sediment replenishment mitigation technique are described in terms of occupied surface of the flume bed and the temporal evolution of erosion and transport of the introduced sediments. It is shown that, under our experimental conditions, complete submersion of the replenishment volume results in complete erosion of the placed sediment, with a high persistence of the added material along the channel length. The geometrical configuration of the replenishment volume plays a key role for the evolution of bed-forms downstream. Parallel configurations lead to a wider spread of material across the channel. Alternated configurations are suitable to produce sediment clustering and high persistence of placed material in the channel. Observed periodic mounds, considered as the initiating condition for alternate bars, follow a wavelength related to the length of the replenishment when the replenishment volumes are alternating.
Cosmological parameters from large scale structure - geometric versus shape information
Hamann, Jan; Hannestad, Steen; Lesgourgues, Julien; Rampf, Cornelius; Wong, Yvonne Y. Y.
2010-07-01
The matter power spectrum as derived from large scale structure (LSS) surveys contains two important and distinct pieces of information: an overall smooth shape and the imprint of baryon acoustic oscillations (BAO). We investigate the separate impact of these two types of information on cosmological parameter estimation for current data, and show that for the simplest cosmological models, the broad-band shape information currently contained in the SDSS DR7 halo power spectrum (HPS) is by far superseded by geometric information derived from the baryonic features. An immediate corollary is that contrary to popular beliefs, the upper limit on the neutrino mass mν presently derived from LSS combined with cosmic microwave background (CMB) data does not in fact arise from the possible small-scale power suppression due to neutrino free-streaming, if we limit the model framework to minimal ΛCDM+mν. However, in more complicated models, such as those extended with extra light degrees of freedom and a dark energy equation of state parameter w differing from -1, shape information becomes crucial for the resolution of parameter degeneracies. This conclusion will remain true even when data from the Planck spacecraft are combined with SDSS DR7 data. In the course of our analysis, we update both the BAO likelihood function by including an exact numerical calculation of the time of decoupling, as well as the HPS likelihood, by introducing a new dewiggling procedure that generalises the previous approach to models with an arbitrary sound horizon at decoupling. These changes allow a consistent application of the BAO and HPS data sets to a much wider class of models, including the ones considered in this work. All the cases considered here are compatible with the conservative 95%-bounds ∑mν < 1.16eV, Neff = 4.8±2.0.
Incorporating Prior Shape into Geometric Active Contours for Face Contour Detection
Institute of Scientific and Technical Information of China (English)
HUANGFuzhen; SUJianbo; XIYugeng
2004-01-01
In this paper a new method that incorporates prior shape information into geometric active contours for face contour detection is proposed. As in general a human face can be treated as an ellipse with a little shape variation, the prior face shape is represented as an elliptical curve. By combining the prior face shape with the powerful geometric active model proposed by Chan and Vese, the improved geometric active model can retain all the advantage of the Chan-Vese model and can detect face contours in images with complex backgrounds accurately even if the image is noisy. Moreover, by implementing the new model in a variational level set framework, automatic topological changes of the model can be achieved naturally and the transformation parameters that map the face boundary to the prior shape can be roughly estimated simultaneously. The experimental results show our procedure to be eiTicient.
San-Millán, Marta; Rissech, Carme; Turbón, Daniel
2017-03-01
This study aims to explore shape variability of the acetabulum during the human adult life span, in relation to sex and age. The human acetabular shape was analysed in 682 os coxae from three different documented skeletal collections from the Iberian Peninsula. Two landmarks and thirty-two sliding semi-landmarks were used for the geometric morphometric procedures and a clock-wise standard was used for orientation. The 180° meridian (6:00) line was positioned over the midpoint of the acetabular notch and 36 reference points in 10° increments along the rim were marked. Data showed that size, sex and age significantly influence acetabular shape variation. Sex differences were significant in individuals younger than 65 years old and were characterised by males exhibiting relatively extended acetabular rim profiles from 10:00 to 1:00, narrower acetabular notches, and reduced acetabular fossae. In addition, three main age-related changes occurred to the acetabular shape in both sexes: outer acetabular profile modification, with extension from 10:00 to 1:00 and reduction from 7:00 to 9:00, acetabular notch narrowing, and acetabular fossa reduction. The age-related changes that were observed are shared by both sexes and seem to be related to bone production associated with age. Specifically, age appears to affect the entire border of the lunate surface: the acetabular rim, both acetabular horns, and the outer edge of the acetabular fossa. Furthermore, shape data confirmed the clover-leaf shape of the acetabular fossa in both males and females. These results improve our understanding of acetabular shape, and assist in refining age-estimation methods and enhancing hip surgery and rehabilitation.
Geometrical Configuration of Cabling as Factor Influencing the Reproducibility of EMC Immunity Tests
Directory of Open Access Journals (Sweden)
I. Szolik
2006-12-01
Full Text Available The paper deals with analysis of the influence of geometrical configuration of device cabling upon voltages induced in cable interfaces. The analyzed properties are the cable height and the cable length for common mode disturbance, and the loop width for differential mode disturbance. The analysis is solved both by analytical calculation and by numerical simulation. Achieved results are compared mutually as well as with results obtained by measurements performed according to standardized procedures. Finally the analyzed parameters are ordered in correspondence of their importance for objectivity and reproducibility of immunity tests against electromagnetic field.
Influence of Global Shapes on Children's Coding of Local Geometric Information in Small-Scale Spaces
Chiang, Noelle C.
2013-01-01
This research uses enclosed whole shapes, rather than visual form fragments, to demonstrate that children's use of local geometric information is influenced by global shapes in small-scale spaces. Three- to six-year-old children and adults participated in two experiments with a table-top task. In Experiment 1, participants were presented with a…
Three- to Six-Year-Old Children's Recognition of Geometric Shapes
Aslan, Durmus; Arnas, Yasare Aktas
2007-01-01
The main purpose of this research was to determine three- to six-year-old pre-schoolers' recognition of basic geometric shapes, the criteria they use to distinguish members of a shape class and whether or not those criteria change in relation to age. Participants were 100 children aged three to six. Data were gathered from individual interviews…
Geometric and unipotent crystals
Berenstein, Arkady; Kazhdan, David
1999-01-01
In this paper we introduce geometric crystals and unipotent crystals which are algebro-geometric analogues of Kashiwara's crystal bases. Given a reductive group G, let I be the set of vertices of the Dynkin diagram of G and T be the maximal torus of G. The structure of a geometric G-crystal on an algebraic variety X consists of a rational morphism \\gamma:X-->T and a compatible family e_i:G_m\\times X-->X, i\\in I of rational actions of the multiplicative group G_m satisfying certain braid-like ...
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
A series of linear and V-shaped oligo(phenylene ethynylene) derivatives 1-3 were synthesized through sequent Sonogashira coupling and propargyl alcohol deprotection reaction in high yields.The alkoxy chains(i.e.,n-hexyloxy groups) were introduced to assure good solubility of compounds 1-3 in common solvents.The photophysical properties of 1-3 in solution depend strongly on the geometries of these compounds.
Stange, Madlen; Aguirre-Fernández, Gabriel; Cooke, Richard G; Barros, Tito; Salzburger, Walter; Sánchez-Villagra, Marcelo R
2016-08-01
Transitions between the marine and freshwater macrohabitat have occurred repeatedly in the evolution of teleost fishes. For example, ariid catfishes have moved from freshwater to marine environments, and vice versa. Opercles, a skeletal feature that has been shown to change during such transitions, were subjected to 2D geometric morphometric analyses in order to investigate evolutionary shape changes during habitat transition in ariid catfishes and to test the influence of habitat on shape changes. A mtDNA marker, which proved useful in previous studies, was used to verify species identities. It greatly improved the assignment of specimens to a species, which are difficult to assign by morphology alone. The application of a mtDNA marker confirmed the occurrence of Notarius biffi in Central America, South of El Salvador. Molecular identification together with principal component analysis (PCA) and further morphological inspection of neurocrania indicated the existence of a cryptic species within Bagre pinnimaculatus. Principal component (PC) scores of individual specimens clustered in morphospace by genus rather than by habitat. Strong phylogenetic structure was detected using a permutation test of PC scores of species means on a phylogenetic tree. Calculation of Pagel's λ suggested that opercle shape evolved according to a Brownian model of evolution. Yet canonical variate analysis (CVA) conducted on the habitat groups showed significant differences in opercle shapes among freshwater and marine species. Overall, opercle shape in tropical American Ariidae appears to be phylogenetically constrained. This verifies the application of opercle shape as a taxonomic tool for species identification in fossil ariid catfishes. At the same time, adaptation to freshwater habitats shows characteristic opercle shape trajectories in ariid catfishes, which might be used to detect habitat preferences in fossils.
Geometric and engineering drawing
Morling, K
2010-01-01
The new edition of this successful text describes all the geometric instructions and engineering drawing information that are likely to be needed by anyone preparing or interpreting drawings or designs with plenty of exercises to practice these principles.
Aerodynamic shape optimization of a HSCT type configuration with improved surface definition
Thomas, Almuttil M.; Tiwari, Surendra N.
1994-01-01
Two distinct parametrization procedures of generating free-form surfaces to represent aerospace vehicles are presented. The first procedure is the representation using spline functions such as nonuniform rational b-splines (NURBS) and the second is a novel (geometrical) parametrization using solutions to a suitably chosen partial differential equation. The main idea is to develop a surface which is more versatile and can be used in an optimization process. Unstructured volume grid is generated by an advancing front algorithm and solutions obtained using an Euler solver. Grid sensitivity with respect to surface design parameters and aerodynamic sensitivity coefficients based on potential flow is obtained using an automatic differentiator precompiler software tool. Aerodynamic shape optimization of a complete aircraft with twenty four design variables is performed. High speed civil transport aircraft (HSCT) configurations are targeted to demonstrate the process.
Geometric hashing and object recognition
Stiller, Peter F.; Huber, Birkett
1999-09-01
We discuss a new geometric hashing method for searching large databases of 2D images (or 3D objects) to match a query built from geometric information presented by a single 3D object (or single 2D image). The goal is to rapidly determine a small subset of the images that potentially contain a view of the given object (or a small set of objects that potentially match the item in the image). Since this must be accomplished independent of the pose of the object, the objects and images, which are characterized by configurations of geometric features such as points, lines and/or conics, must be treated using a viewpoint invariant formulation. We are therefore forced to characterize these configurations in terms of their 3D and 2D geometric invariants. The crucial relationship between the 3D geometry and its 'residual' in 2D is expressible as a correspondence (in the sense of algebraic geometry). Computing a set of generating equations for the ideal of this correspondence gives a complete characterization of the view of independent relationships between an object and all of its possible images. Once a set of generators is in hand, it can be used to devise efficient recognition algorithms and to give an efficient geometric hashing scheme. This requires exploiting the form and symmetry of the equations. The result is a multidimensional access scheme whose efficiency we examine. Several potential directions for improving this scheme are also discussed. Finally, in a brief appendix, we discuss an alternative approach to invariants for generalized perspective that replaces the standard invariants by a subvariety of a Grassmannian. The advantage of this is that one can circumvent many annoying general position assumptions and arrive at invariant equations (in the Plucker coordinates) that are more numerically robust in applications.
Saturation and geometrical scaling
Praszalowicz, Michal
2016-01-01
We discuss emergence of geometrical scaling as a consequence of the nonlinear evolution equations of QCD, which generate a new dynamical scale, known as the saturation momentum: Qs. In the kinematical region where no other energy scales exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on the ratio pT=Qs, and the energy dependence enters solely through the energy dependence of the saturation momentum. We confront the hypothesis of GS in different systems with experimental data.
Free Eenergy as a Dynamical and Geometric Invariant (or Can You Hear the Shape of a Potential?)
Pollicott, M
2003-01-01
The lattice gas provides an important and illuminating family of models in statistical physics. An interaction $\\Phi$ on a lattice $L \\subset \\Bbb Z^d$ determines an idealized lattice gas system with potential $A_\\Phi$. The pressure $P(A_\\Phi)$ and free energy $F_{A_\\Phi}(\\beta)= -(1/\\beta) P(\\beta A_\\Phi)$ are fundamental characteristics of the system. However, even for the simplest lattice systems, the information about the potential that the free energy captures is subtle and poorly understood. We study whether, or to what extent, potentials for certain model systems are determined by their free energy. In particular, we show that for a one-dimensional lattice gas, the free energy of finite range interactions typically determines the potential, up to natural equivalence, and there is always at most a finite ambiguity; we exhibit exceptional potentials where uniqueness fails; and we establish deformation rigidity for the free energy. The proofs use a combination of thermodynamic formalism, algebraic geometr...
Directory of Open Access Journals (Sweden)
Erika Hingst-Zaher
2000-06-01
Full Text Available Abstract We analyzed ontogenetic patterns of landmarks for 169 laboratory-raised specimens of Calomys expulsus, at 0, 5, 10, 20, 30, 50, 100, 200, and 300 days of age, using two-dimensional geometric morphometrics. There is sexual dimorphism in size, with males smaller than females at earlier ages, but larger after 50 days. Differences in shape between sexes are strong only until 10 days of age, suggesting that shape is more constrained than size. Combining sexes, there is strong variation in size with age, reduced after 200 days, while most of the variation in shape occurs before 20 days. This dissociation is common for sigmodontine rodents, and might be the basis of heterochronic processes responsible for the morphological variation of this South American group. Centroid size does not show any reduction in the coefficient of variation over ages, while Procrustes distances within sucessive ages are reduced after 20 days. Uniform component and the more global partial warps explain most of the shape changes with age. Cranial and Facial parts of the skull increase in size at different rates with a relative lengthening of the snout and decrease in height of the braincase. We were unable to detect a clear pattern of integration for the rostrum and braincase, besides that shown by landmark displacements.
Content-Based Search on a Database of Geometric Models: Identifying Objects of Similar Shape
Energy Technology Data Exchange (ETDEWEB)
XAVIER, PATRICK G.; HENRY, TYSON R.; LAFARGE, ROBERT A.; MEIRANS, LILITA; RAY, LAWRENCE P.
2001-11-01
The Geometric Search Engine is a software system for storing and searching a database of geometric models. The database maybe searched for modeled objects similar in shape to a target model supplied by the user. The database models are generally from CAD models while the target model may be either a CAD model or a model generated from range data collected from a physical object. This document describes key generation, database layout, and search of the database.
Configured fuel briquet and method
Energy Technology Data Exchange (ETDEWEB)
Peters, S.M.
1985-01-29
A charcoal briquet of any selected shape is configured to provide a preselected ignition time and total burning time response. A method of constructing such a briquet for any desired combustion response includes empirically deriving expressions for ignition time as a function of briquet volume, surface area and density, and for burn time as a function of volume and density, and configuring any selected shape briquet in accordance with the parameters found to provide such selected performance.
GEOMETRIC ANALYSIS OF PLANAR SHAPES WITH APPLICATIONS TO CELL DEFORMATIONS
Directory of Open Access Journals (Sweden)
Ximo Gual-Arnau
2015-09-01
Full Text Available Shape analysis is of great importance in many fields such as computer vision, medical imaging, and computational biology. In this paper we focus on a shape space in which shapes are represented by means of planar closed curves. In this shape space a new metric was recently introduced with the result that this shape space has the property of being isometric to an infinite-dimensional Grassmann manifold of 2-dimensional subspaces. Using this isometry it is possible, from Younes et al. (2008, to explicitly describe geodesics, a task that previously was not at all easy. Our aim is twofold, namely: to use this general theory in order to show some applications to the study of erythrocytes, using digital images of peripheral blood smears, in the treatment of sickle cell disease; and, since normal erythrocytes are almost circular and many Sickle cells have elliptical shape, to particularize the computation of geodesics and distances between shapes using this metric to planar objects considered as deformations of a template (circle or ellipse. The applications considered include: shape interpolation, shape classification, and shape clustering.
Reducing Turbulent Transport in Toroidal Configurations via Shaping
Energy Technology Data Exchange (ETDEWEB)
H.E. Mynick, N. Pomphrey and P. Xanthopoulos
2011-04-20
Recent progress in reducing turbulent transport in stellarators and tokamaks by 3D shaping using a stellarator optimization code in conjunction with a gyrokinetic code is presented. The original applications of the method focussed on ion temperature gradient transport in a quasi-axisymmetric stellarator design. Here, an examination of both other turbulence channels and other starting configurations is initiated. It is found that the designs evolved for transport from ion temperature gradient turbulence also display reduced transport from other transport channels whose modes are also stabilized by improved curvature, such as electron temperature gradient and ballooning modes. The optimizer is also applied to evolving from a tokamak, finding appreciable turbulence reduction for these devices as well. From these studies, improved understanding is obtained of why the deformations found by the optimizer are beneficial, and these deformations are related to earlier theoretical work in both stellarators and tokamaks.
A probabilistic approach to randomness in geometric configuration of scalable origami structures
Liu, Ke; Paulino, Glaucio; Gardoni, Paolo
2015-03-01
Origami, an ancient paper folding art, has inspired many solutions to modern engineering challenges. The demand for actual engineering applications motivates further investigation in this field. Although rooted from the historic art form, many applications of origami are based on newly designed origami patterns to match the specific requirenments of an engineering problem. The application of origami to structural design problems ranges from micro-structure of materials to large scale deployable shells. For instance, some origami-inspired designs have unique properties such as negative Poisson ratio and flat foldability. However, origami structures are typically constrained by strict mathematical geometric relationships, which in reality, can be easily violated, due to, for example, random imperfections introduced during manufacturing, or non-uniform deformations under working conditions (e.g. due to non-uniform thermal effects). Therefore, the effects of uncertainties in origami-like structures need to be studied in further detail in order to provide a practical guide for scalable origami-inspired engineering designs. Through reliability and probabilistic analysis, we investigate the effect of randomness in origami structures on their mechanical properties. Dislocations of vertices of an origami structure have different impacts on different mechanical properties, and different origami designs could have different sensitivities to imperfections. Thus we aim to provide a preliminary understanding of the structural behavior of some common scalable origami structures subject to randomness in their geometric configurations in order to help transition the technology toward practical applications of origami engineering.
Iso-geometric shape optimization of magnetic density separators
DEFF Research Database (Denmark)
Dang Manh, Nguyen; Evgrafov, Anton; Gravesen, Jens
2014-01-01
Purpose The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly...... is obtained at the cost of a pole cover shape that differs per pole. This limitation has negligible impact on the manufacturing of the separator. The new pole cover shapes therefore lead to improved performance of the density separation. Practical implications Due to the larger uniformity the generated field......, these shapes should enable larger amounts of waste to be processed than the previous design. Originality/value This paper treats the shapes optimization of magnetic density separators systematically and presents new shapes for the ferromagnetic poles covers....
Rhagoletis pomonella (Walsh) and Rhagoletis zephyria Snow both occur in the Pacific Northwest of the U. S. and are frequently confused with one another due to their morphological similarity. The apple maggot, R. pomonella, is a threat to commercial apples in the Pacific Northwest, whereas R. zephyr...
Geometric Algorithms for Part Orienting and Probing
Panahi, F.
2015-01-01
In this thesis, detailed solutions are presented to several problems dealing with geometric shape and orientation of an object in the field of robotics and automation. We first have considered a general model for shape variations that allows variation along the entire boundary of an object, both in
Liu, Jun Jie; Dolev, Maya Bar; Celik, Yeliz; Wettlaufer, J S; Braslavsky, Ido
2012-01-01
The melting of pure axisymmetric ice crystals has been described previously by us within the framework of so-called geometric crystal growth. Nonequilibrium ice crystal shapes evolving in the presence of hyperactive antifreeze proteins (hypAFPs) are experimentally observed to assume ellipsoidal geometries ("lemon" or "rice" shapes). To analyze such shapes we harness the underlying symmetry of hexagonal ice Ih and extend two-dimensional geometric models to three-dimensions to reproduce the experimental dissolution process. The geometrical model developed will be useful as a quantitative test of the mechanisms of interaction between hypAFPs and ice.
Directory of Open Access Journals (Sweden)
Jatin Shringi
2016-04-01
Full Text Available The objective of paper is to carry out the study of optimization of thermal performance of solar radiation for optimum geometrical shape of a box type solar cooker. The study involves fabrication of different geometries for on field evaluation in region. In observation temperature profiles are plotted against equal time intervals and then figure of merit is calculated. In solar cooking heat transfer modes i.e. conduction, convection and radiation plays a dominant role. The solar technologies for cooking are highly useful in developing countries like India which is enriched with sunshine. The results show that trapezoidal shape is better than other geometrical shapes made and the information will likely impact on design of future solar cookers.
Energy Technology Data Exchange (ETDEWEB)
Mohammadi, M A; Sobhanian, S [Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of); Wong, C S [Plasma Research Laboratory, Physics Department, University of Malaya, Kuala Lumpur (Malaysia); Lee, S; Lee, P; Rawat, R S, E-mail: rajdeep.rawat@nie.edu.s [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University (Singapore)
2009-02-21
The effect of three different anode shapes, flat, tapered and hemispherical, on the x-ray emission characteristics of a neon filled UNU-ICTP plasma focus device is investigated. The current sheath dynamics, in the radial collapse phase, has been simultaneously interrogated using the laser shadowgraphy method to understand the variation in x-ray emission characteristics for anodes of different shapes used in the experiments. The maximum neon soft x-ray (SXR) yield for the flat anode is about 7.5 {+-} 0.4 J at 4 mbar, whereas for hemispherical and tapered anodes the neon SXR is almost halved with the optimum pressure shifting to a lower value of 3 mbar. The laser shadowgraphic images confirm that the reduction in the overall neon SXR yield is due to the reduced focused plasma column length for these anodes. The relative HXR yield was the highest for the hemispherical anode followed by the tapered and the flat anodes in that order. The shadowgraphic images and the voltage probe signals confirmed that for the hemispherical anode the multiple-pinch phenomenon was most commonly observed, which could be responsible for multiple HXR bursts for this anode with maximum HXR yields.
Computational Contact Mechanics Geometrically Exact Theory for Arbitrary Shaped Bodies
Konyukhov, Alexander
2013-01-01
This book contains a systematical analysis of geometrical situations leading to contact pairs -- point-to-surface, surface-to-surface, point-to-curve, curve-to-curve and curve-to-surface. Each contact pair is inherited with a special coordinate system based on its geometrical properties such as a Gaussian surface coordinate system or a Serret-Frenet curve coordinate system. The formulation in a covariant form allows in a straightforward fashion to consider various constitutive relations for a certain pair such as anisotropy for both frictional and structural parts. Then standard methods well known in computational contact mechanics such as penalty, Lagrange multiplier methods, combination of both and others are formulated in these coordinate systems. Such formulations require then the powerful apparatus of differential geometry of surfaces and curves as well as of convex analysis. The final goals of such transformations are then ready-for-implementation numerical algorithms within the finite e...
Evolution of regular geometrical shapes in fiber lumens
Le, Ngoc Lieu
2017-08-17
The geometry of polymeric hollow fibers for hemodialysis or desalination is a key factor determining their performance. Deformations are frequently observed, but they are rather random. Here we were able to exactly control the shape evolution of the internal channels or lumens of polymeric hollow fibers, leading to polygonal geometries with increasing number of sides. The elasticity of the incipient channel skin and instabilities during fiber formation are affected by the internal coagulant fluid composition and flow rate; and highly influence the polygonal shape. We propose a holistic explanation by analyzing the thermodynamic, kinetic and rheological aspects involved in the skin formation and their synergy.
Ko, William L.; Fleischer, Van Tran; Lung, Shun-Fat
2017-01-01
For shape predictions of structures under large geometrically nonlinear deformations, Curved Displacement Transfer Functions were formulated based on a curved displacement, traced by a material point from the undeformed position to deformed position. The embedded beam (depth-wise cross section of a structure along a surface strain-sensing line) was discretized into multiple small domains, with domain junctures matching the strain-sensing stations. Thus, the surface strain distribution could be described with a piecewise linear or a piecewise nonlinear function. The discretization approach enabled piecewise integrations of the embedded-beam curvature equations to yield the Curved Displacement Transfer Functions, expressed in terms of embedded beam geometrical parameters and surface strains. By entering the surface strain data into the Displacement Transfer Functions, deflections along each embedded beam can be calculated at multiple points for mapping the overall structural deformed shapes. Finite-element linear and nonlinear analyses of a tapered cantilever tubular beam were performed to generate linear and nonlinear surface strains and the associated deflections to be used for validation. The shape prediction accuracies were then determined by comparing the theoretical deflections with the finiteelement- generated deflections. The results show that the newly developed Curved Displacement Transfer Functions are very accurate for shape predictions of structures under large geometrically nonlinear deformations.
Ambrosetti, Antonio; Malchiodi, Andrea
2009-01-01
This volume contains lecture notes on some topics in geometric analysis, a growing mathematical subject which uses analytical techniques, mostly of partial differential equations, to treat problems in differential geometry and mathematical physics. The presentation of the material should be rather accessible to non-experts in the field, since the presentation is didactic in nature. The reader will be provided with a survey containing some of the most exciting topics in the field, with a series of techniques used to treat such problems.
Medium-spin states of the neutron-rich 87,89Br isotopes: configurations and shapes
Nyakó, B. M.; Timár, J.; Csatlós, M.; Dombrádi, Zs; Krasznahorkay, A.; Kuti, I.; Sohler, D.; Tornyi, T. G.; Czerwiński, M.; Rząca-Urban, T.; Urban, W.; Bączyk, P.; Atanasova, L.; Balabanski, D. L.; Sieja, K.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; de France, G.; Simpson, G. S.; Ur, C. A.
2016-06-01
Medium-spin excited states of the neutron-rich 87Br and 89Br nuclei were observed and studied for the first time. They were populated in fission of 235U induced by the cold-neutron beam of the PF1B facility of the Institut Laue-Langevin, Grenoble. The measurement of γ radiation following fission has been performed using the EXILL array of Ge detectors. The observed level schemes were compared with results of large valence space shell model calculations. Both medium-spin level schemes consist of band-like structures, which can be understood as bands built on the πf 5/2, πp 3/2 and πg 9/2 configurations. Both nuclei have 5/2- ground state spin-parity contrary to the odd-mass Br isotopes containing fewer neutrons, which have 3/2- ground state spin-parity. On the basis of the properties of the πg 9/2 decoupled bands the deformations of the 87Br and 89Br fit to the systematics of nuclei in the region. 87Br is close to the vibrational limit, while 89Br is more rotational.
Bidimensionality and Geometric Graphs
Fomin, Fedor V; Saurabh, Saket
2011-01-01
In this paper we use several of the key ideas from Bidimensionality to give a new generic approach to design EPTASs and subexponential time parameterized algorithms for problems on classes of graphs which are not minor closed, but instead exhibit a geometric structure. In particular we present EPTASs and subexponential time parameterized algorithms for Feedback Vertex Set, Vertex Cover, Connected Vertex Cover, Diamond Hitting Set, on map graphs and unit disk graphs, and for Cycle Packing and Minimum-Vertex Feedback Edge Set on unit disk graphs. Our results are based on the recent decomposition theorems proved by Fomin et al [SODA 2011], and our algorithms work directly on the input graph. Thus it is not necessary to compute the geometric representations of the input graph. To the best of our knowledge, these results are previously unknown, with the exception of the EPTAS and a subexponential time parameterized algorithm on unit disk graphs for Vertex Cover, which were obtained by Marx [ESA 2005] and Alber and...
Directory of Open Access Journals (Sweden)
Christine Cherry E. Solon
2012-06-01
Full Text Available Objective: This study describes morphological variations of the face of hypertensive women when compared to non-hypertensives.Material and Methods: Digital images of the faces of 54 non-hypertensive and 41 hypertensive women were used in this study. Forty-one manuallypositioned landmarks were on front face images, while twenty-eight landmarks were collected on left and right face images, the Cartesiancoordinates of which were extracted using an image analysis and processing software. The faces were then aligned using Procrustes alignmentof the Cartesian coordinates to eliminate size differences and rotational translation. The size residuals left after the alignment were then used toreconstruct the face truss network using thin-plate spline grids. Variations in facial morphology were then explored using the methods of relativewarps analysis and partial warps analysis. Results: Principal Component Analysis revealed that in both populations of females, five or sixprincipal components contribute most to the variation that exist among individuals. Results for fluctuating asymmetry are higher compared toindividual variation, with even higher values in hypertensive individuals compared to non-hypertensive. Scatterplots of residual asymmetrybetween the two groups further revealed the distinct differences existing between them.
Geometric Number Systems and Spinors
Sobczyk, Garret
2015-01-01
The real number system is geometrically extended to include three new anticommuting square roots of plus one, each such root representing the direction of a unit vector along the orthonormal coordinate axes of Euclidean 3-space. The resulting geometric (Clifford) algebra provides a geometric basis for the famous Pauli matrices which, in turn, proves the consistency of the rules of geometric algebra. The flexibility of the concept of geometric numbers opens the door to new understanding of the nature of space-time, and of Pauli and Dirac spinors as points on the Riemann sphere, including Lorentz boosts.
Oral Drug Delivery Systems Comprising Altered Geometric Configurations for Controlled Drug Delivery
Directory of Open Access Journals (Sweden)
Priya Bawa
2011-12-01
Full Text Available Recent pharmaceutical research has focused on controlled drug delivery having an advantage over conventional methods. Adequate controlled plasma drug levels, reduced side effects as well as improved patient compliance are some of the benefits that these systems may offer. Controlled delivery systems that can provide zero-order drug delivery have the potential for maximizing efficacy while minimizing dose frequency and toxicity. Thus, zero-order drug release is ideal in a large area of drug delivery which has therefore led to the development of various technologies with such drug release patterns. Systems such as multilayered tablets and other geometrically altered devices have been created to perform this function. One of the principles of multilayered tablets involves creating a constant surface area for release. Polymeric materials play an important role in the functioning of these systems. Technologies developed to date include among others: Geomatrix® multilayered tablets, which utilizes specific polymers that may act as barriers to control drug release; Procise®, which has a core with an aperture that can be modified to achieve various types of drug release; core-in-cup tablets, where the core matrix is coated on one surface while the circumference forms a cup around it; donut-shaped devices, which possess a centrally-placed aperture hole and Dome Matrix® as well as “release modules assemblage”, which can offer alternating drug release patterns. This review discusses the novel altered geometric system technologies that have been developed to provide controlled drug release, also focusing on polymers that have been employed in such developments.
Cavaignac, Etienne; Li, Ke; Faruch, Marie; Savall, Frederic; Chiron, Philippe; Huang, W; Telmon, Norbert
2017-12-01
Ethnic dimorphism in the distal femur has never been studied in a three-dimensional analysis focused on shape instead of size. Yet, this dimorphism has direct implications in orthopedic surgery and in anthropology. The goal of this study was to show that differences in distal femur shape related to ethnic dimorphism could be identified, visualized, and quantified using 3D geometric morphometric analysis. CT scans of the distal femur were taken from 482 patients who were free of any bone-related pathology: 240 patients were European (E) and 242 were Asian (A). Ten osteometric landmarks based on standard bone landmarks used in anthropometry were placed on these scans. Geometric morphometric analysis, principal component analysis (PCA), canonical variates analysis (CVA), and other discriminant analyses (Goodall's F-test and Mahalanobis distance) were performed. A cross-validation analysis was carried out to determine the percentage of cases in which the ethnicity was correctly estimated. The shape of the E and A distal femur differed significantly (Goodall's F = 94.43, P geometric morphometric analysis made it possible to demonstrate these differences. The large number of subjects studied has helped modernize the references for certain bone measurements, with direct implication for orthopedic surgery and anthropology.
Institute of Scientific and Technical Information of China (English)
Yang Mou; Ran Xian-Jin; Cui Yan; Wang Rui-Qiang
2011-01-01
The efficiency of the calculation of Green's function (GF) for nano-devices is very important because the calculation is often needed to be repeated countlessly. We present a set of efficient algorithms for the numerical calculation of GF for devices with arbitrary shapes and multi-terminal configurations. These algorithms can be used to calculate the specified blocks related to the transmission,the diagonals needed by the local density of states calculation,and the full matrix of GF,to meet different calculation levels. In addition,the algorithms for the non-equilibrium occupation and current flow are also given. All these algorithms are described using the basic theory of GF,based on a new partition strategy of the computational area. We apply these algorithms to the tight-binding graphene lattice to manifest their stability and efficiency. We also discuss the physics of the calculation results.
Forces between arrays of permanent magnets of basic geometric shapes
DEFF Research Database (Denmark)
Vokoun, D.; Beleggia, Marco
2014-01-01
We provide formulas for evaluating the magnetic force between two permanent magnet arrays, regularly spaced over a square lattice. We focus on three basic shapes of magnets constituting the arrays: cylinder, sphere and rectangular prism. When the lattice parameter is large, the expressions can...... be used to calculate the force between two single magnets in a computationally efficient way. The calculations are validated experimentally by measuring the attraction force between two single permanent magnets, where we demonstrate a fair agreement within about 15%....
A geometrical approach for automatic shape restoration of the left ventricle.
Directory of Open Access Journals (Sweden)
May-Ling Tan
Full Text Available This paper describes an automatic algorithm that uses a geometry-driven optimization approach to restore the shape of three-dimensional (3D left ventricular (LV models created from magnetic resonance imaging (MRI data. The basic premise is to restore the LV shape such that the LV epicardial surface is smooth after the restoration and that the general shape characteristic of the LV is not altered. The Maximum Principle Curvature (k1 and the Minimum Principle Curvature (k2 of the LV epicardial surface are used to construct a shape-based optimization objective function to restore the shape of a motion-affected LV via a dual-resolution semi-rigid deformation process and a free-form geometric deformation process. A limited memory quasi-Newton algorithm, L-BFGS-B, is then used to solve the optimization problem. The goal of the optimization is to achieve a smooth epicardial shape by iterative in-plane and through-plane translation of vertices in the LV model. We tested our algorithm on 30 sets of LV models with simulated motion artifact generated from a very smooth patient sample, and 20 in vivo patient-specific models which contain significant motion artifacts. In the 30 simulated samples, the Hausdorff distances with respect to the Ground Truth are significantly reduced after restoration, signifying that the algorithm can restore geometrical accuracy of motion-affected LV models. In the 20 in vivo patient-specific models, the results show that our method is able to restore the shape of LV models without altering the general shape of the model. The magnitudes of in-plane translations are also consistent with existing registration techniques and experimental findings.
Buildings, spiders, and geometric Satake
Fontaine, Bruce; Kuperberg, Greg
2011-01-01
Let G be a simple algebraic group. Labelled trivalent graphs called webs can be used to product invariants in tensor products of minuscule representations. For each web, we construct a configuration space of points in the affine Grassmannian. Via the geometric Satake correspondence, we relate these configuration spaces to the invariant vectors coming from webs. In the case G = SL(3), non-elliptic webs yield a basis for the invariant spaces. The non-elliptic condition, which is equivalent to the condition that the dual diskoid of the web is CAT(0), is explained by the fact that affine buildings are CAT(0).
DEFF Research Database (Denmark)
Winter, Pawel; Sterner, Henrik; Sterner, Peter
2009-01-01
We provide a unified description of (weighted) alpha shapes, beta shapes and the corresponding simplicialcomplexes. We discuss their applicability to various protein-related problems. We also discuss filtrations of alpha shapes and touch upon related persistence issues.We claim that the full...... potential of alpha-shapes and related geometrical constructs in protein-related problems yet remains to be realized and verified. We suggest parallel algorithms for (weighted) alpha shapes, and we argue that future use of filtrations and kinetic variants for larger proteins will need such implementation....
Harmonic and geometric analysis
Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao
2015-01-01
This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights. The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...
fMRI Evidence of ‘Mirror’ Responses to Geometric Shapes
Press, Clare; Catmur, Caroline; Cook, Richard; Widmann, Hannah; Heyes, Cecilia; Bird, Geoffrey
2012-01-01
Mirror neurons may be a genetic adaptation for social interaction [1]. Alternatively, the associative hypothesis [2], [3] proposes that the development of mirror neurons is driven by sensorimotor learning, and that, given suitable experience, mirror neurons will respond to any stimulus. This hypothesis was tested using fMRI adaptation to index populations of cells with mirror properties. After sensorimotor training, where geometric shapes were paired with hand actions, BOLD response was measured while human participants experienced runs of events in which shape observation alternated with action execution or observation. Adaptation from shapes to action execution, and critically, observation, occurred in ventral premotor cortex (PMv) and inferior parietal lobule (IPL). Adaptation from shapes to execution indicates that neuronal populations responding to the shapes had motor properties, while adaptation to observation demonstrates that these populations had mirror properties. These results indicate that sensorimotor training induced populations of cells with mirror properties in PMv and IPL to respond to the observation of arbitrary shapes. They suggest that the mirror system has not been shaped by evolution to respond in a mirror fashion to biological actions; instead, its development is mediated by stimulus-general processes of learning within a system adapted for visuomotor control. PMID:23251653
Bonciocat, C A; Grosu, G; Ghiţă, S
1997-01-01
In this work a theoretical model was used in combination with testings on normal subjects to get more insight in the role of the departure from circularity or dispersion of the shapes in visual perception. The model was inspired by the observation that the intensity of the effect of a given level of contrast of a shape usually increases, for the same area, with the shape being better concentrated around a center. The model introduces as a measurable characteristic the degree of concentration or dispersion of a shape with respect to a center. The measure was based on the maximum of the convolution integral of the characteristic function of the shape with the weighting function 1/2 pi r, r being the distance between the point of convolution and the surface element to be integrated. A program for the calculation of the degree of concentration of figures and other related processing operations was developed in Turbo Pascal language on a 486 PC. The program included the possibility to generate various figures and to operate on them various transformations such as strangulation, fragmentation with separation of fragments. The model introduces a center of the figure, the point best surrounded by the whole figure, with a geometric and visual significance, as resulting from the good concordance between its calculated and perceived positioning in different relatively simple shapes. In symmetrical compact figures subjected to a central separation or narrowing two centres appear entering the two resulting nuclear parts; a good concordance between model and perception was again observed in this transition to two centres and their subsequent positions in the two nuclear parts. In accord to model prediction, testings showed a very pronounced dependence of the summation efficiency over a contrasting area on the degree of dispersion of the area. This is reflected in the drastic decrease upon figure dispersion of the intensity with which a given brightness or colour contrast is
NURBS-based geometric inverse reconstruction of free-form shapes
Directory of Open Access Journals (Sweden)
Deepika Saini
2017-01-01
Full Text Available In this study, a geometric inverse algorithm is proposed for reconstructing free-form shapes (curves and surfaces in space from their arbitrary perspective images using a Non-Uniform Rational B-Spline (NURBS model. In particular, NURBS model is used to recover information about the required shape in space. An optimization problem is formulated to fit the NURBS to the digitized data in the images. Control points and weights are treated as the decision variables in the optimization process. The 3D shape reconstruction problem is reduced to a problem that comprises stereo reconstruction of control points and computation of the corresponding weights. The correspondence between the control points in the two images is obtained using a third image. The performance of the proposed algorithm was validated by taking several examples based on the synthetic and real images. Comparisons were made with a point-based method in terms of various types of errors.
Geometric Computations on Indecisive and Uncertain Points
Jorgensen, Allan; Phillips, Jeff M
2012-01-01
We study computing geometric problems on uncertain points. An uncertain point is a point that does not have a fixed location, but rather is described by a probability distribution. When these probability distributions are restricted to a finite number of locations, the points are called indecisive points. In particular, we focus on geometric shape-fitting problems and on building compact distributions to describe how the solutions to these problems vary with respect to the uncertainty in the points. Our main results are: (1) a simple and efficient randomized approximation algorithm for calculating the distribution of any statistic on uncertain data sets; (2) a polynomial, deterministic and exact algorithm for computing the distribution of answers for any LP-type problem on an indecisive point set; and (3) the development of shape inclusion probability (SIP) functions which captures the ambient distribution of shapes fit to uncertain or indecisive point sets and are admissible to the two algorithmic constructi...
Determination of the Stable Slope Configuration of Oval-Shaped Furrow Pits
Institute of Scientific and Technical Information of China (English)
ZHU Nai-long; ZHANG Shi-xiong
2004-01-01
The space effects of oval-shaped furrow pit slopes were analyzed by the elastic mechanics principle. The interaction of limit equilibrium slope angle, friction coefficient, cohesion and horizontal radius of oval-shaped furrow pits has been derived. The oval trumpet-like rock mass is homogeneous and elastic while only loadedby its dead weight. The interaction indicates that the deeper an oval-shaped furrow pit is excavated, the greater thelimit equilibrium slope angle. Both the theory base for reducing stripping waste rock in an oval- shaped furrow pitand the basic way to determine the configuration of a stable slope were developed from the mentioned interaction.The theory includes the preceding principles of stability analysis of slopes. Compared with the configuration deter-mined by traditional theory of slope stability, a great quantity of stripping waste rock can be reduced by that deter-mined in this paper under stable conditions.
Weinreich, Daniel M; Knies, Jennifer L
2013-10-01
The functional synthesis uses experimental methods from molecular biology, biochemistry and structural biology to decompose evolutionarily important mutations into their more proximal mechanistic determinants. However these methods are technically challenging and expensive. Noting strong formal parallels between R.A. Fisher's geometric model of adaptation and a recent model for the phenotypic basis of protein evolution, we sought to use the former to make inferences into the latter using data on pairwise fitness epistasis between mutations. We present an analytic framework for classifying pairs of mutations with respect to similarity of underlying mechanism on this basis, and also show that these data can yield an estimate of the number of mutationally labile phenotypes underlying fitness effects. We use computer simulations to explore the robustness of our approach to violations of analytic assumptions and analyze several recently published datasets. This work provides a theoretical complement to the functional synthesis as well as a novel test of Fisher's geometric model.
Different Modes of Communicating Geometric Shapes, through a Game, in Kindergarten
Skoumpourdi, Chrysanthi
2016-01-01
Kindergarten children's (5-6 years old) ability to communicate geometric shapes, to their classmates, in different modes--verbally, gesturally, schematically--through a game, was investigated. The game motivated the children to describe the shapes in the different modes, by emerging children's thinking process, communication capacity as well as…
Iso-geometric shape optimization of magnetic density separators
2014-01-01
PurposeThe waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly reduces the required amount of permanent magnet material. The purpose of this paper is to alleviate the undesired end-effects in this design by altering the shape of the ferromagnetic covers of the ...
Features in geometric receiver shapes modelling bat-like directivity patterns.
Guarato, Francesco; Andrews, Heather; Windmill, James F C; Jackson, Joseph; Pierce, Gareth; Gachagan, Anthony
2015-09-03
The directional properties of bat ears as receivers is a current area of interest in ultrasound research. This paper presents a new approach to analyse the relationship between morphological features and acoustical properties of the external ear of bat species. The beam pattern of Rousettus leschenaultii's right ear is measured and compared to that of receiver structures whose design is inspired by the bat ear itself and made of appropriate geometric shapes. The regular shape of these receivers makes it possible to control the key reception parameters and thus to understand the effect on the associated beam pattern of the parameters themselves. Measurements show one receiver structure has a beam pattern very similar to that of R. leschenaultii's ear, thus explaining the function of individual parts constituting its ear. As it is applicable to all bat species, this approach can provide a useful tool to investigate acoustics in bats, and possibly other mammals.
The Nuclear Shape Phase Transitions Studied within the Geometric Collective Model
Directory of Open Access Journals (Sweden)
Khalaf A. M.
2013-04-01
Full Text Available In the framework of the Geometric Collective Model (GCM, quantum phase transition between spherical and deformed shapes of doubly even nuclei are investigated. The validity of the model is examined for the case of lanthanide chains Nd / Sm and actinide chains Th / U. The parameters of the model were obtained by performing a computer simulated search program in order to obtain minimum root mean square deviations be- tween the calculated and the experimental excitation energies. Calculated potential en- ergy surfaces (PES’s describing all deformation effects of each nucleus are extracted. Our systematic studies on lanthanide and actinide chains have revealed a shape transi- tion from spherical vibrator to axially deformed rotor when moving from the lighter to the heavier isotopes.
Geometric optimization and sums of algebraic functions
Vigneron, Antoine E.
2014-01-01
We present a new optimization technique that yields the first FPTAS for several geometric problems. These problems reduce to optimizing a sum of nonnegative, constant description complexity algebraic functions. We first give an FPTAS for optimizing such a sum of algebraic functions, and then we apply it to several geometric optimization problems. We obtain the first FPTAS for two fundamental geometric shape-matching problems in fixed dimension: maximizing the volume of overlap of two polyhedra under rigid motions and minimizing their symmetric difference. We obtain the first FPTAS for other problems in fixed dimension, such as computing an optimal ray in a weighted subdivision, finding the largest axially symmetric subset of a polyhedron, and computing minimum-area hulls.
Institute of Scientific and Technical Information of China (English)
戴志军; 李春初
2004-01-01
Coastline configuration indexes of 34 typical arc-shaped coasts in South China are investigated by the method of principal component analysis, and meanwhile deposition and geomorphologic features of arc-shaped coast are also analyzed. The results show: (1) The configuration of arc-shaped coast in South China is of the characteristic of variability and complexity. (2) The wave power and the openings of the bay are the decisive factors to result in the changes of the configuration of the arc-shaped coast in South China, however, incidence direction of the wave has no effect on configuration development of the coast. (3) Commonly, geomorphologic modes of the arc-shaped coast system in South China consist of barriers, lagoons and tidal-inlets, and can be divided into four types:the openings of the bay leaning to the east, the openings of the bay leaning to the south, the openings of the bay leaning to the west and the openings of the bay leaning to the north.
Cai, Yongchun; Wang, Ci; Song, Chao; Li, Zhi
2017-05-01
L-shaped configuration is a commonly used stimulus configuration in studying horizontal vertical illusion. Here, we report that the horizontal vertical illusion is substantially underestimated when the L-shaped configuration is used for evaluating the illusion. Experiment 1 found that, in a length perception task, the perceived length of a vertical bar was about 10% longer than that of a horizontal bar with the same physical size. Similar amount of HVI was found in a length comparison task, in which the length of a horizontal bar was compared to that of a vertical bar and the two bars were presented separately in space or in time. In contrast, when the length comparison task was conducted with the two bars being arranged in a connected L-shape, the illusion was halved in strength. Experiment 2 and 3 studied what might be the cause of this L-shape induced HVI-underestimation. Two factors were investigated: the connectedness of the two lines, and the 45° absolute orientation or the 45° inner angle information embedded in the upright isosceles L-shape. The results showed that the HVI strength was not much affected when the 45° absolute orientation and the 45° angle information was made useless for the length comparison task. In contrast, the illusion was significantly reduced in strength whenever the two lines were separated as compared to when they were connected. These results suggested that the connectedness of the two lines must underlie the underestimation of the horizontal vertical illusion in the L-shaped configurations.
Biess, Armin
2013-01-01
The study of the kinematic and dynamic features of human arm movements provides insights into the computational strategies underlying human motor control. In this paper a differential geometric approach to movement control is taken by endowing arm configuration space with different non-Euclidean metric structures to study the predictions of the generalized minimum-jerk (MJ) model in the resulting Riemannian manifold for different types of human arm movements. For each metric space the solution of the generalized MJ model is given by reparametrized geodesic paths. This geodesic model is applied to a variety of motor tasks ranging from three-dimensional unconstrained movements of a four degree of freedom arm between pointlike targets to constrained movements where the hand location is confined to a surface (e.g., a sphere) or a curve (e.g., an ellipse). For the latter speed-curvature relations are derived depending on the boundary conditions imposed (periodic or nonperiodic) and the compatibility with the empirical one-third power law is shown. Based on these theoretical studies and recent experimental findings, I argue that geodesics may be an emergent property of the motor system and that the sensorimotor system may shape arm configuration space by learning metric structures through sensorimotor feedback.
Biess, Armin
2013-01-01
The study of the kinematic and dynamic features of human arm movements provides insights into the computational strategies underlying human motor control. In this paper a differential geometric approach to movement control is taken by endowing arm configuration space with different non-Euclidean metric structures to study the predictions of the generalized minimum-jerk (MJ) model in the resulting Riemannian manifold for different types of human arm movements. For each metric space the solution of the generalized MJ model is given by reparametrized geodesic paths. This geodesic model is applied to a variety of motor tasks ranging from three-dimensional unconstrained movements of a four degree of freedom arm between pointlike targets to constrained movements where the hand location is confined to a surface (e.g., a sphere) or a curve (e.g., an ellipse). For the latter speed-curvature relations are derived depending on the boundary conditions imposed (periodic or nonperiodic) and the compatibility with the empirical one-third power law is shown. Based on these theoretical studies and recent experimental findings, I argue that geodesics may be an emergent property of the motor system and that the sensorimotor system may shape arm configuration space by learning metric structures through sensorimotor feedback.
Directory of Open Access Journals (Sweden)
Ritwik Mondal
2015-01-01
Interpretation & conclusion: It has been marked out that the geometric morphometrics utilizes powerful and comprehensive statistical procedures to analyze the shape differences of a morphological feature, assuming that the studied mosquitoes may represent different genotypes and probably come from one diverse gene pool.
Bermejo, Fernando; Di Paolo, Ezequiel A.; Hüg, Mercedes X.; Arias, Claudia
2015-01-01
The sensorimotor approach proposes that perception is constituted by the mastery of lawful sensorimotor regularities or sensorimotor contingencies (SMCs), which depend on specific bodily characteristics and on actions possibilities that the environment enables and constrains. Sensory substitution devices (SSDs) provide the user information about the world typically corresponding to one sensory modality through the stimulation of another modality. We investigate how perception emerges in novice adult participants equipped with vision-to-auditory SSDs while solving a simple geometrical shape recognition task. In particular, we examine the distinction between apparatus-related SMCs (those originating mostly in properties of the perceptual system) and object-related SMCs (those mostly connected with the perceptual task). We study the sensorimotor strategies employed by participants in three experiments with three different SSDs: a minimalist head-mounted SSD, a traditional, also head-mounted SSD (the vOICe) and an enhanced, hand-held echolocation device. Motor activity and fist-person data are registered and analyzed. Results show that participants are able to quickly learn the necessary skills to distinguish geometric shapes. Comparing the sensorimotor strategies utilized with each SSD we identify differential features of the sensorimotor patterns attributable mostly to the device, which account for the emergence of apparatus-based SMCs. These relate to differences in sweeping strategies between SSDs. We identify, also, components related to the emergence of object-related SMCs. These relate mostly to exploratory movements around the border of a shape. The study provides empirical support for SMC theory and discusses considerations about the nature of perception in sensory substitution. PMID:26106340
Steyerl, A; Müller, G; Golub, R
2015-01-01
The important role of geometric phases in searches for a permanent electric dipole moment of the neutron, using Ramsey separated oscillatory field nuclear magnetic resonance, was first investigated by Pendlebury $\\textit{et al.}$ [Phys. Rev. A $\\mathbf{70}$, 032102 (2004)]. Their analysis was based on the Bloch equations. In subsequent work using the spin density matrix Lamoreaux and Golub [Phys. Rev. A $\\mathbf{71}$, 032104 (2005)] showed the usual relation between the frequency shifts and the correlation functions of the fields seen by trapped particles in general fields (Redfield theory). More recently we presented a solution of the Schr\\"odinger equation for spin-$1/2$ particles in circular cylindrical traps with smooth walls and exposed to arbitrary fields [Steyerl $\\textit{et al.}$, Phys.Rev. A $\\mathbf{89}$, 052129 (2014)]. Here we extend this work to show how the Redfield theory follows directly from the Schr\\"odinger equation solution and include wall roughness, cylindrical trap geometry with arbitra...
National Aeronautics and Space Administration — In practically all air-vehicle MDO studies to date involving configuration shape optimization, dynamic Aeroservoelastic constraints had to be left out. Flutter, gust...
Height and Tilt Geometric Texture
DEFF Research Database (Denmark)
Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas
2009-01-01
We propose a new intrinsic representation of geometric texture over triangle meshes. Our approach extends the conventional height field texture representation by incorporating displacements in the tangential plane in the form of a normal tilt. This texture representation offers a good practical...... compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...
Polysoaps: Configurations and Elasticity
Halperin, A.
1997-03-01
Simple polymers are very long, flexible, linear molecules. Amphiphiles, soaps, are small molecules comprising of a part that prefers water over oil and a part that prefers oil over water. By combining the two we arrive at an interesting, little explored, class of materials: Polysoaps. These comprise of a water soluble backbone incorporating, at intervals, covalently bound amphiphilic monomers. In water, the polymerised amphiphiles aggregate into self assembled units known as micelles. This induces a dramatic modification of the spatial configurations of the polymers. What were featureless random coils now exhibit intramolecular, hierachial self organisation. Due to this self organisation it is necessary to modify the paradigms describing the large scale behaviour of these polymers: Their configurations, dimensions and elasticity. Understanding the behaviour of these polymers is of practical interest because of their wide range of industrial applications, ranging from cosmetics to paper coating. It is of fundamental interest because polysoaps are characterised by a rugged free energy landscape that is reminiscent of complex systems such as proteins and glasses. The talk concerns theoretical arguments regarding the following issues: (i) The design parameters that govern the spatial configurations of the polysoaps, (ii) The interaction between polysoaps and free amphiphiles, (iii) The effect of the intramolecular self organisation on the elasticity of the chains.
DEFF Research Database (Denmark)
Lee, Daniel Sang-Hoon; Jia, Wenwen; Cai, Jianguo
2015-01-01
Leader), Japan and Denmark, expandable bars of two degrees of freedom (1 x translational and 1 x rotational) were developed to achieve the geometrical compatibility of the single-meridian grid deployable system. The objective of the current research is to investigate the further applications...... of the expandable bars for creation of dynamic three-dimensional (3D) space using scissor-type deployable system. The research starts with the detail design and prototype construction of the expandable bars in collaboration between the Royal Danish Academy, School of Architecture in Denmark and School of Civil...
DEFF Research Database (Denmark)
Strykowski, Gabriel; Boschetti, F.; Papp, G.
2005-01-01
, a rough 3D shape of the source is modelled-a model consisting of the vertical mass columns of equal height. The horizontal extension is implied by the surface gravity signal. Subsequently, the shape of each source body is modified to obtain a better fit to the surface gravity data. In each modification......) and only weakly constrained by the seismic information. The result was the reconstruction of the 'rough' 3D geometry of the source bodies and the estimation of a constant mass density contrast to the surroundings. A possible extension of this technique for detailed studies of the geological model......We invert 2D surface gravity data constrained both by geological and seismic information. We use a number of pre-processing tools in order to reduce the general multi-body inversion into several single-body inversions, whereby we can reduce the overall complexity of the inversion task. This is done...
Directory of Open Access Journals (Sweden)
Sundus Hussein Abd
2012-01-01
Full Text Available In this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. The impact of changing the body location within the air duct and the air speed are also demonstrated. The cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. Each cylinder was heated to a certain temperature and put inside the duct at certain locations. The temperature of the cylinder was then monitored. The heat transfer coefficient were then calculated for forced convection for several Reynolds number (4555-18222.The study covered free convection impact for values of Rayleigh number ranging between (1069-3321. Imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. These imperical equations were found to be in good comparison with that of other sources.
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
梁科; 侯自新
2001-01-01
Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.
Metastable vacua and geometric deformations
Amariti, A; Girardello, L; Mariotti, A
2008-01-01
We study the geometric interpretation of metastable vacua for systems of D3 branes at non isolated toric deformable singularities. Using the L^{aba} examples, we investigate the relations between the field theoretic susy breaking and restoration and the complex deformations of the CY singularities.
Directory of Open Access Journals (Sweden)
Carlo Stephen O. Moneva
2012-06-01
Full Text Available Prior studies have shown different insights about sexual shell dimorphism in the snails of family Viviparidae. This study was conductedto evaluate and determine the occurence of sexual dimorphism and shape variation in the shells of the viviparid snail, Vivipara angularisMuller, from three characters (ventral/aperture, dorsal, and top/whorl using geometric morphometric analyses. All the three shell charactersexhibited significant sexual shell dimorphism, this may be due to adaptations for brooding of the viviparid snails. Results indicate employmentof different shell characters subjected to geometric morphometric analysis other than the aperture, in order to discriminate between sexes ofthe snails accurately.
Stabilization of systems with one degree of underactuation with energy shaping, a geometric approach
Gharesifard, Bahman
2010-01-01
A geometric formulation for stabilization of systems with one degree of underactuation which fully solves the energy shaping problem for these system is given. The results show that any linearly controllable simple mechanical system with one degree of underactuation is stabilizable by energy shaping, possibly via a closed-loop metric which is not necessarily positive-definite. An example of a system with one degree of underactuation is provided for which the stabilization by energy shaping method is not achievable using a positive-definite closed-loop metric.
Optimal sensor configuration for flexible structures with multi-dimensional mode shapes
Chang, Minwoo; Pakzad, Shamim N.
2015-05-01
A framework for deciding the optimal sensor configuration is implemented for civil structures with multi-dimensional mode shapes, which enhances the applicability of structural health monitoring for existing structures. Optimal sensor placement (OSP) algorithms are used to determine the best sensor configuration for structures with a priori knowledge of modal information. The signal strength at each node is evaluated by effective independence and modified variance methods. Euclidean norm of signal strength indices associated with each node is used to expand OSP applicability into flexible structures. The number of sensors for each method is determined using the threshold for modal assurance criterion (MAC) between estimated (from a set of observations) and target mode shapes. Kriging is utilized to infer the modal estimates for unobserved locations with a weighted sum of known neighbors. A Kriging model can be expressed as a sum of linear regression and random error which is assumed as the realization of a stochastic process. This study presents the effects of Kriging parameters for the accurate estimation of mode shapes and the minimum number of sensors. The feasible ranges to satisfy MAC criteria are investigated and used to suggest the adequate searching bounds for associated parameters. The finite element model of a tall building is used to demonstrate the application of optimal sensor configuration. The dynamic modes of flexible structure at centroid are appropriately interpreted into the outermost sensor locations when OSP methods are implemented. Kriging is successfully used to interpolate the mode shapes from a set of sensors and to monitor structures associated with multi-dimensional mode shapes.
Effect of the nozzle tip’s geometrical shape on electrospray deposition of organic thin films
Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko
2017-04-01
Electrospray deposition (ESD) is a favorable wet fabrication technique for organic thin films. We investigated the effects of the nozzle tip’s geometrical shape on the spraying properties of an organic solution used for ESD. Five types of cylindrical metal nozzles with zero (flat end) to four protrusions at the tips were prepared for depositing a solution of a small-molecule compound, tris(8-hydroxyquinolinato)aluminum (Alq3) solution. We confirmed that the diameter of the deposited droplets and their size dispersion decreased with an increase in the number of protrusions. The area occupation ratio of small droplets with a diameter smaller than 2 µm increased from 21 to 83% as the number of protrusions was increased from zero to four. The surface roughness root mean square of 60-nm-thick Alq3 films substantially improved from 32.5 to 6.8 nm with increasing number of protrusions.
Sensitivity Analysis and Optimization of Aerodynamic Configurations with Blend Surfaces
Thomas, A. M.; Tiwari, S. N.
1997-01-01
A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point Form method. A graphic interface software is developed which dynamically changes the surface of the airplane configuration with the change in input design variable. The software is made user friendly and is targeted towards the initial conceptual development of any aerodynamic configurations. Grid sensitivity with respect to surface design parameters and aerodynamic sensitivity coefficients based on potential flow is obtained using an Automatic Differentiation precompiler software tool ADIFOR. Aerodynamic shape optimization of the complete aircraft with twenty four design variables is performed. Unstructured and structured volume grids and Euler solutions are obtained with standard software to demonstrate the feasibility of the new surface definition.
Configuration spaces geometry, topology and representation theory
Cohen, Frederick; Concini, Corrado; Feichtner, Eva; Gaiffi, Giovanni; Salvetti, Mario
2016-01-01
This book collects the scientific contributions of a group of leading experts who took part in the INdAM Meeting held in Cortona in September 2014. With combinatorial techniques as the central theme, it focuses on recent developments in configuration spaces from various perspectives. It also discusses their applications in areas ranging from representation theory, toric geometry and geometric group theory to applied algebraic topology.
Shirani, M.; Kadkhodaei, M.
2014-12-01
Ferromagnetic shape memory alloys (FSMAs) and magnetic shape memory alloys (MSMAs) are metallic alloys that can undergo inelastic responses when exposed to magnetic fields. Several constitutive models have been proposed so far to model the behaviors of FSMAs. In this work, the effects of loading history on reorientation start conditions are considered, and it is shown that reorientation start conditions are not fixed values; rather, they change with respect to the amount of loading history. To consider the effects of loading history on reorientation start conditions, an available phase diagram in stress-field space is generalized to reorientation surfaces in stress-field-loading history space. Correspondingly, kinetic laws are derived in a continuum framework to be used with the reorientation surfaces to determine the amount of the martensitic variant 2 volume fraction. Based on the geometry of the reorientation surfaces, conditions that must be satisfied to ensure the continuation of reorientations are obtained. Available experimental findings validate the proposed model and the reorientation surfaces.
MS S4.03.002 - Adjoint-Based Design for Configuration Shaping
Nemec, Marian; Aftosmis, Michael J.
2009-01-01
This slide presentation discusses a method of inverse design for low sonic boom using adjoint-based gradient computations. It outlines a method for shaping a configuration in order to match a prescribed near-field signature.
Experimental Study on the Effect of Exit Geometric Configurations on Hydrodynamics in CFB
Directory of Open Access Journals (Sweden)
Xiaolei Qiao
2013-05-01
Full Text Available The exit configurations of CFB strongly influence the bulk density profile and the internal circulation of the bed material, which is called the end effect. This study analyzes the influence of three exit geometries and two narrowed exit geometries on hydrodynamics. Experiments indicate that the exit with the projected roof in CFB may be used as a separator and the projected height has a maximum. Narrowing the bed cross section near the bed exit zone is a simple and effective way to enhance the internal circulation and reduce the circulation of bed material simultaneously.
Evaluation method on steering for the shape-shifting robot in different configurations
Chang, Jian; Li, Bin; Wang, Chong; Zheng, Huaibing; Li, Zhiqiang
2016-01-01
The evaluation method on steering is based on qualitative manner in existence, which causes the result inaccurate and fuzziness. It reduces the efficiency of process execution. So the method by quantitative manner for the shape-shifting robot in different configurations is proposed. Comparing to traditional evaluation method, the most important aspects which can influence the steering abilities of the robot in different configurations are researched in detail, including the energy, angular velocity, time and space. In order to improve the robustness of system, the ideal and slippage conditions are all considered by mathematical model. Comparing to the traditional weighting confirming method, the extent of robot steering method is proposed by the combination of subjective and objective weighting method. The subjective weighting method can show more preferences of the experts and is based on five-grade scale. The objective weighting method is based on information entropy to determine the factors. By the sensors fixed on the robot, the contract force between track grouser and ground, the intrinsic motion characteristics of robot are obtained and the experiment is done to prove the algorithm which is proposed as the robot in different common configurations. Through the method proposed in the article, fuzziness and inaccurate of the evaluation method has been solved, so the operators can choose the most suitable configuration of the robot to fulfil the different tasks more quickly and simply.
Garuma Abdisa Denu; Zongchen Liu; Jiao Fu; Hongxing Wang
2017-01-01
We report the effect of geometrical shape of diamond nanowire on its mechanical properties. Finite element modeling using COMSOL Multiphysics software is used to simulate various diamond nanowire with circular, square, rectangular, hexagonal and triangular cross-sections. A bending test under concentrated load applied at one of the free ends is simulated using FEM. The force response of the nanowire under different loading is studied for the various cross-sections. The dimensions of each cros...
Directory of Open Access Journals (Sweden)
J. J. Moyano
2017-02-01
Full Text Available This paper proposes a procedure for the search of a geometrical similarity pattern in architectural heritage by means of calculating probability indexes to support hypotheses initially endorsed by documentary sources. The buildings analysed are the Cathedral of Seville and the Church of Santiago, in Jerez, Spain. The 3D models of their selected pillars are obtained by means of Terrestrial Laser Scanning (TLS, Optical Scanning (OS and photogrammetry through image-based modelling software (SFM-IBM. To this end, a procedure for the comparison of shapes is established. It is based on similarity statistics, the determination of homologous points and the agreement of characteristic sections. Here, two key aspects are considered: on the one hand, the metric standpoint; on the other hand, historical-graphical features of the 3D models: composition, techniques, styles, and historical-graphical documentary sources. Thus, putting aside the mere dimensional analysis, the sections are compared with graphical patterns and models of which the same authorship – stonemasons working in that age – is accurately known. As a result, the outcomes of this research reveal the geometrical similarity between the elements of the pillars of the Cathedral of Seville and the Church of Santiago.
Moyano, J. J.; Barrera, J. A.; Nieto, J. E.; Marín, D.; Antón, D.
2017-02-01
This paper proposes a procedure for the search of a geometrical similarity pattern in architectural heritage by means of calculating probability indexes to support hypotheses initially endorsed by documentary sources. The buildings analysed are the Cathedral of Seville and the Church of Santiago, in Jerez, Spain. The 3D models of their selected pillars are obtained by means of Terrestrial Laser Scanning (TLS), Optical Scanning (OS) and photogrammetry through image-based modelling software (SFM-IBM). To this end, a procedure for the comparison of shapes is established. It is based on similarity statistics, the determination of homologous points and the agreement of characteristic sections. Here, two key aspects are considered: on the one hand, the metric standpoint; on the other hand, historical-graphical features of the 3D models: composition, techniques, styles, and historical-graphical documentary sources. Thus, putting aside the mere dimensional analysis, the sections are compared with graphical patterns and models of which the same authorship - stonemasons working in that age - is accurately known. As a result, the outcomes of this research reveal the geometrical similarity between the elements of the pillars of the Cathedral of Seville and the Church of Santiago.
Audiometric shape and presbycusis.
Demeester, Kelly; van Wieringen, Astrid; Hendrickx, Jan-jaap; Topsakal, Vedat; Fransen, Erik; van Laer, Lut; Van Camp, Guy; Van de Heyning, Paul
2009-04-01
The aim of this study was to describe the prevalence of specific audiogram configurations in a healthy, otologically screened population between 55 and 65 years old. The audiograms of 1147 subjects (549 males and 598 females between 55 and 65 years old) were collected through population registries and classified according to the configuration of hearing loss. Gender and noise/solvent-exposure effects on the prevalence of the different audiogram shapes were determined statistically. In our population 'Flat' audiograms were most dominantly represented (37%) followed by 'High frequency Gently sloping' audiograms (35%) and 'High frequency Steeply sloping' audiograms (27%). 'Low frequency Ascending' audiograms, 'Mid frequency U-shape' audiograms and 'Mid frequency Reverse U-shape' audiograms were very rare (together less than 1%). The 'Flat'-configuration was significantly more common in females, whereas the 'High frequency Steeply sloping'-configuration was more common in males. Exposure to noise and/or solvents did not change this finding. In addition, females with a 'Flat' audiogram had a significantly larger amount of overall hearing loss compared to males. Furthermore, our data reveal a significant association between the prevalence of 'High frequency Steeply sloping' audiograms and the degree of noise/solvent exposure, despite a relatively high proportion of non-exposed subjects showing a 'High frequency Steeply sloping' audiogram as well.
Laser beam shaping theory and techniques
Dickey, Fred M
2000-01-01
The mathematical and physical theory of lossless beam shaping; Gaussian beam shaping - diffraction theory and design; geometrical methods; optimization-based techniques for laser shaping optics; beam shaping with diffractive diffusers; multi-aperture beam integration systems; classical (non-laser) methods; current technology of beam profile measurements.
Van Hooff, T.; Blocken, B.; Aanen, L.; Bronsema, B.
2011-01-01
Wind tunnel experiments and Computational Fluid Dynamics (CFD) are used to analyse the flow conditions in a venturi-shaped roof, with focus on the underpressure in the narrowest roof section (contraction). This underpressure can be used to partly or completely drive the natural ventilation of the bu
Science, Art and Geometrical Imagination
Luminet, J -P
2009-01-01
From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental role of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Durer, Kepler, Escher, Grisey or the present author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as beauty, conciseness and emotional approach of the world.
Science, art and geometrical imagination
Luminet, Jean-Pierre
2011-06-01
From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental rôle of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Dürer, Kepler, Escher, Grisey or the author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as on beauty, conciseness and an emotional approach of the world.
Generalized geometrically convex functions and inequalities.
Noor, Muhammad Aslam; Noor, Khalida Inayat; Safdar, Farhat
2017-01-01
In this paper, we introduce and study a new class of generalized functions, called generalized geometrically convex functions. We establish several basic inequalities related to generalized geometrically convex functions. We also derive several new inequalities of the Hermite-Hadamard type for generalized geometrically convex functions. Several special cases are discussed, which can be deduced from our main results.
Osusky, Lana Maria
The increase in the availability and power of computational resources over the last fifteen years has contributed to the development of many different types of numerical optimization methods and created a large area of research focussed on numerical aerodynamic shape optimization and, more recently, high-fidelity multidisciplinary optimization. Numerical optimization provides dramatic savings when designing new aerodynamic configurations, as it allows the designer to focus more on the development of a well-posed design problem rather than on performing an exhaustive search of the design space via the traditional cut-and-try approach, which is expensive and time-consuming. It also reduces the dependence on the designer's experience and intuition, which can potentially lead to more optimal designs. Numerical optimization methods are particularly attractive when designing novel, unconventional aircraft for which the designer has no pre-existing studies or experiences from which to draw; these methods have the potential to discover new designs that might never have been arrived at without optimization. This work presents an extension of an efficient gradient-based numerical aerodynamic shape optimization algorithm to enable optimization in turbulent flow. The algorithm includes an integrated geometry parameterization and mesh movement scheme, an efficient parallel Newton-Krylov-Schur algorithm for solving the Reynolds-Averaged Navier-Stokes (RANS) equations, which are fully coupled with the one-equation Spalart-Allmaras turbulence model, and a discrete-adjoint gradient evaluation. In order to develop an efficient methodology for optimization in turbulent flows, the viscous and turbulent terms in the ii governing equations were linearized by hand. Additionally, a set of mesh refinement tools was introduced in order to obtain both an acceptable control volume mesh and a sufficiently refined computational mesh from an initial coarse mesh. A series of drag minimization
Effects of laser parameters on the geometrical characteristics of peg-shaped bionic coupling unit
Zhang, Baoyu; Zhang, Zhihui; Liang, Yunhong; Yan, Qiongqiong; Ren, Luquan
2014-12-01
Peg-shaped bionic coupling unit (PBCU) processed by pulse laser is effective in anti-adhesion, anti-drag, anti-wear and anti-fatigue application. To obtain desired structural and morphological characteristics of the PBCU for industrial manufacturing, selection of proper processing parameters gradually becomes a growing important problem. Traditionally, the procedure of parameter selecting is often cost-plus and time-consuming. In this work, a statistical analysis of fabricating PBCU on the surface of medium carbon steel was conducted. The laser processing parameters utilized in the experiment and analysis are peak power 4-8 kW, pulse duration 6-16 ms and defocusing amount 6-10 mm. A series of mathematical models regarding the relationship between geometrical characteristics of PBCU and laser processing parameters were developed and checked. The results indicate that the developed models can be adequately used to control the structural and morphological characteristics of PBCU within the scope of analysis. Based on the models, the formation mechanism of the structural and morphological characteristics under different laser parameters were analyzed and discussed.
CCH-based geometric algorithms for SVM and applications
Institute of Scientific and Technical Information of China (English)
Xin-jun PENG; Yi-fei WANG
2009-01-01
The support vector machine (SVM) is a novel machine learning tool in data mining. In this paper, the geometric approach based on the compressed convex hull (CCH) with a mathematical framework is introduced to solve SVM classification problems. Compared with the reduced convex hull (RCH), CCH preserves the shape of geometric solids for data sets; meanwhile, it is easy to give the necessary and sufficient condition for determining its extreme points. As practical applications of CCH, spare and probabilistic speed-up geometric algorithms are developed. Results of numerical experiments show that the proposed algorithms can reduce kernel calculations and display nice performances.
The Multipoint Global Shape Optimization of Flying Configuration with Movable Leading Edges Flaps
Directory of Open Access Journals (Sweden)
Adriana NASTASE
2012-12-01
Full Text Available The aerodynamical global optimized (GO shape of flying configuration (FC, at two cruising Mach numbers, can be realized by morphing. Movable leading edge flaps are used for this purpose. The equations of the surfaces of the wing, of the fuselage and of the flaps in stretched position are approximated in form of superpositions of homogeneous polynomes in two variables with free coefficients. These coefficients together with the similarity parameters of the planform of the FC are the free parameters of the global optimization. Two enlarged variational problems with free boundaries occur. The first one consists in the determination of the GO shape of the wing-fuselageFC, with the flaps in retracted position, which must be of minimum drag, at higher cruising Mach number. The second enlarged variational problem consists in the determination of the GO shape of the flaps in stretched position in such a manner that the entire FC shall be of minimum drag at the second lower Mach number. The iterative optimum-optimorum (OO theory of the author is used for the solving of these both enlarged variational problems. The inviscid GO shape of the FC is used only in the first step of iteration and the own developed hybrid solutions for the compressible Navier-Stokes partial-differential equations (PDEs are used for the determination of the friction drag coefficient and up the second step of iteration of OO theory.
Oscillating Filaments: I - Oscillation and Geometrical Fragmentation
Gritschneder, Matthias; Burkert, Andreas
2016-01-01
We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid based AMR-code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, e.g. with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process `geometrical fragmentation'. In our realization the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristical scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. ...
López, O. E.; Guazzotto, L.
2017-03-01
The Grad-Shafranov-Bernoulli system of equations is a single fluid magnetohydrodynamical description of axisymmetric equilibria with mass flows. Using a variational perturbative approach [E. Hameiri, Phys. Plasmas 20, 024504 (2013)], analytic approximations for high-beta equilibria in circular, elliptical, and D-shaped cross sections in the high aspect ratio approximation are found, which include finite toroidal and poloidal flows. Assuming a polynomial dependence of the free functions on the poloidal flux, the equilibrium problem is reduced to an inhomogeneous Helmholtz partial differential equation (PDE) subject to homogeneous Dirichlet conditions. An application of the Green's function method leads to a closed form for the circular solution and to a series solution in terms of Mathieu functions for the elliptical case, which is valid for arbitrary elongations. To extend the elliptical solution to a D-shaped domain, a boundary perturbation in terms of the triangularity is used. A comparison with the code FLOW [L. Guazzotto et al., Phys. Plasmas 11(2), 604-614 (2004)] is presented for relevant scenarios.
Donut-shaped high-dose configuration for proton beam radiation therapy
Energy Technology Data Exchange (ETDEWEB)
Rutz, H.P.; Lomax, A.J. [Div. of Radiation Medicine, Paul Scherrer Inst., Villigen PSI (Switzerland)
2005-01-01
Background: the authors report on the conception and first clinical application of a donut-shaped high-dose configuration for proton therapy (PT). This approach allows one to intensify target volume dose coverage for targets encompassing a critical, dose-limiting structure - like here, the cauda equina -, whilst delivering minimal dose to other healthy structures surrounding the target, thereby reducing the integral dose. Methods and results: intensity-modulated PT methods (IMPT) for spot scanning were applied to create and deliver a donut-shaped high-dose configuration with protons, allowing treating > 75% of the target with at least 95% of the prescribed dose of 72.8 CGE, whilst restricting dose to the cauda equina to 60-65 CGE. Integral dose was lower by a factor of 3.3 as compared to intensity-modulated radiotherapy with photons (IMXT). Conclusion: IMPT and spot scanning technology allow a potentially clinically useful approach which is also applicable to spare other critical structures passing through a target volume, including spinal cord, optic nerves, chiasm, brain stem, or urethra. (orig.)
Peng, H.Y.
2013-11-13
We report that electrode engineering, particularly tailoring the metal work function, measurement configuration and geometric shape, has significant effects on the bipolar resistive switching (RS) in lateral memory devices based on self-doped SrTiO3 (STO) single crystals. Metals with different work functions (Ti and Pt) and their combinations are used to control the junction transport (either ohmic or Schottky-like). We find that the electric bias is effective in manipulating the concentration of oxygen vacancies at the metal/STO interface, influencing the RS characteristics. Furthermore, we show that the geometric shapes of electrodes (e.g., rectangular, circular, or triangular) affect the electric field distribution at the metal/oxide interface, thus plays an important role in RS. These systematic results suggest that electrode engineering should be deemed as a powerful approach toward controlling and improving the characteristics of RS memories. 2013 Author(s).
Shape descriptors for mode-shape recognition and model updating
Wang, W.; Mottershead, J. E.; Mares, C.
2009-08-01
The most widely used method for comparing mode shapes from finite elements and experimental measurements is the Modal Assurance Criterion (MAC), which returns a single numerical value and carries no explicit information on shape features. New techniques, based on image processing (IP) and pattern recognition (PR) are described in this paper. The Zernike moment descriptor (ZMD), Fourier descriptor (FD), and wavelet descriptor (WD), presented in this article, are the most popular shape descriptors having properties that include efficiency of expression, robustness to noise, invariance to geometric transformation and rotation, separation of local and global shape features and computational efficiency. The comparison of mode shapes is readily achieved by assembling the shape features of each mode shape into multi-dimensional shape feature vectors (SFVs) and determining the distances separating them.
On chromatic and geometrical calibration
DEFF Research Database (Denmark)
Folm-Hansen, Jørgen
1999-01-01
of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how......The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... the DLT can be extended with non-linear models of the common lens aberrations/errors some of them caused by manufacturing defects like decentering and thin prism distortion. The relation between a warping and the non-linear defects are shown. The issue of making a good resampling of an image by using...
Efficient Configuration Space Construction and Optimization for Motion Planning
Directory of Open Access Journals (Sweden)
Jia Pan
2015-03-01
Full Text Available The configuration space is a fundamental concept that is widely used in algorithmic robotics. Many applications in robotics, computer-aided design, and related areas can be reduced to computational problems in terms of configuration spaces. In this paper, we survey some of our recent work on solving two important challenges related to configuration spaces: how to efficiently compute an approximate representation of high-dimensional configuration spaces; and how to efficiently perform geometric proximity and motion planning queries in high-dimensional configuration spaces. We present new configuration space construction algorithms based on machine learning and geometric approximation techniques. These algorithms perform collision queries on many configuration samples. The collision query results are used to compute an approximate representation for the configuration space, which quickly converges to the exact configuration space. We also present parallel GPU-based algorithms to accelerate the performance of optimization and search computations in configuration spaces. In particular, we design efficient GPU-based parallel k-nearest neighbor and parallel collision detection algorithms and use these algorithms to accelerate motion planning.
Taking Shape: Supporting Preschoolers' Acquisition of Geometric Knowledge through Guided Play
Fisher, Kelly R.; Hirsh-Pasek, Kathy; Newcombe, Nora; Golinkoff, Roberta M.
2013-01-01
Shape knowledge, a key aspect of school readiness, is part of early mathematical learning. Variations in how children are exposed to shapes may affect the pace of their learning and the nature of their shape knowledge. Building on evidence suggesting that child-centered, playful learning programs facilitate learning more than other methods, 4-to…
Manipulation of the geometric and electronic parameters of metal nanocatalysts
Laskar, Moitree
Metal nanoparticles find wide use in the field of catalysis owing to their high surface to volume ratio. The catalytic activity depends on the interaction between the molecular substrate and catalyst surface. This substrate-catalyst interaction can be regulated by manipulating the geometric and electronic parameters of these nanoparticles. The shape and size of the nanoparticles dictate the geometric parameters whereas their composition controls the electronics of these catalysts. Manipulation of these parameters can be used to tune catalytic activities; hence, a better understanding of their regulation will help in designing efficient catalysts. The synthesis and characterization of a series of monometallic Pd and core shell Au Pd nanoparticles with varying shapes and sizes will be discussed in this presentation. These nanocrystals were used to catalyze two model reactions: selective hydrogenation of 2-hexyne and oxidation of formic acid. Comparison of their catalytic activities by varying one parameter at a time (either size or shape) helps to identify the effect of geometric parameters on catalysis. Additionally, comparison of particles with varying composition but same geometric features provides insight into how the electronics underlying the catalysis can be manipulated through nanostructure architecture. We find that a balance in binding interaction between the substrate and catalyst surface is necessary to design an efficient catalyst and can be achieved with shape-controlled core shell nanocrystals.
Geometric Modeling and Reasoning of Human-Centered Freeform Products
Wang, Charlie C L
2013-01-01
The recent trend in user-customized product design requires the shape of products to be automatically adjusted according to the human body’s shape, so that people will feel more comfortable when wearing these products. Geometric approaches can be used to design the freeform shape of products worn by people, which can greatly improve the efficiency of design processes in various industries involving customized products (e.g., garment design, toy design, jewel design, shoe design, and design of medical devices, etc.). These products are usually composed of very complex geometric shapes (represented by free-form surfaces), and are not driven by a parameter table but a digital human model with free-form shapes or part of human bodies (e.g., wrist, foot, and head models). Geometric Modeling and Reasoning of Human-Centered Freeform Products introduces the algorithms of human body reconstruction, freeform product modeling, constraining and reconstructing freeform products, and shape optimization for improving...
Eyal, Ofer; Raz, Eli
2016-07-01
Dimensional analysis (DA) is commonly used to solve problems in various fields in physics. In this work we concentrated on problems in electrostatics (and magneto-statics) that deal with finding the field (or potential) caused by a distribution of charges (or currents) on a family of scale-invariant geometrical shapes. An infinite cone is one example of such a shape; zooming-in or zooming-out of this shape will leave it unchanged. Once we choose the shape, a monomial length-dependence-of-charge distribution on such a shape is chosen. The interplay between the chosen geometry and the chosen distribution yields an added value to the DA method as shown in this paper. Examples, like finding the field of infinite cones, the field created by semi-infinite wires, and the distribution of current on a conducting spherical shell, are presented. The field of an infinite cone is calculated and found to be uniform in the region containing the axis of symmetry; moreover, for a specific opening angle the field vanishes. Another example of using DA is to show that the electric field caused by a moving charge is radial for any velocity which is constant without the need to use relativistic calculations.
Reuther, James; Alonso, Juan Jose; Rimlinger, Mark J.; Jameson, Antony
1996-01-01
This work describes the application of a control theory-based aerodynamic shape optimization method to the problem of supersonic aircraft design. The design process is greatly accelerated through the use of both control theory and a parallel implementation on distributed memory computers. Control theory is employed to derive the adjoint differential equations whose solution allows for the evaluation of design gradient information at a fraction of the computational cost required by previous design methods (13, 12, 44, 38). The resulting problem is then implemented on parallel distributed memory architectures using a domain decomposition approach, an optimized communication schedule, and the MPI (Message Passing Interface) Standard for portability and efficiency. The final result achieves very rapid aerodynamic design based on higher order computational fluid dynamics methods (CFD). In our earlier studies, the serial implementation of this design method (19, 20, 21, 23, 39, 25, 40, 41, 42, 43, 9) was shown to be effective for the optimization of airfoils, wings, wing-bodies, and complex aircraft configurations using both the potential equation and the Euler equations (39, 25). In our most recent paper, the Euler method was extended to treat complete aircraft configurations via a new multiblock implementation. Furthermore, during the same conference, we also presented preliminary results demonstrating that the basic methodology could be ported to distributed memory parallel computing architectures [241. In this paper, our concem will be to demonstrate that the combined power of these new technologies can be used routinely in an industrial design environment by applying it to the case study of the design of typical supersonic transport configurations. A particular difficulty of this test case is posed by the propulsion/airframe integration.
Geometrical splitting and reduction of Feynman diagrams
Davydychev, Andrei I.
2016-10-01
A geometrical approach to the calculation of N-point Feynman diagrams is reviewed. It is shown that the geometrical splitting yields useful connections between Feynman integrals with different momenta and masses. It is demonstrated how these results can be used to reduce the number of variables in the occurring functions.
Parabolas: Connection between Algebraic and Geometrical Representations
Shriki, Atara
2011-01-01
A parabola is an interesting curve. What makes it interesting at the secondary school level is the fact that this curve is presented in both its contexts: algebraic and geometric. Being one of Apollonius' conic sections, the parabola is basically a geometric entity. It is, however, typically known for its algebraic characteristics, in particular…
Rosette Central Configurations, Degenerate central configurations and bifurcations
Lei, Jinzhi
2009-01-01
In this paper we find a class of new degenerate central configurations and bifurcations in the Newtonian $n$-body problem. In particular we analyze the Rosette central configurations, namely a coplanar configuration where $n$ particles of mass $m_1$ lie at the vertices of a regular $n$-gon, $n$ particles of mass $m_2$ lie at the vertices of another $n$-gon concentric with the first, but rotated of an angle $\\pi/n$, and an additional particle of mass $m_0$ lies at the center of mass of the system. This system admits two mass parameters $\\mu=m_0/m_1$ and $\\ep=m_2/m_1$. We show that, as $\\mu$ varies, if $n> 3$, there is a degenerate central configuration and a bifurcation for every $\\ep>0$, while if $n=3$ there is a bifurcations only for some values of $\\epsilon$.
Fused traditional and geometric morphometrics demonstrate pinniped whisker diversity.
Ginter, Carly C; DeWitt, Thomas J; Fish, Frank E; Marshall, Christopher D
2012-01-01
Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length) were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics) was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC), which results in
Fused Traditional and Geometric Morphometrics Demonstrate Pinniped Whisker Diversity
Ginter, Carly C.; DeWitt, Thomas J.; Fish, Frank E.; Marshall, Christopher D.
2012-01-01
Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length) were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics) was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC), which results in
Fused traditional and geometric morphometrics demonstrate pinniped whisker diversity.
Directory of Open Access Journals (Sweden)
Carly C Ginter
Full Text Available Vibrissae (whiskers are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC, which
Martínez, Fabio; Romero, Eduardo; Dréan, Gaël; Simon, Antoine; Haigron, Pascal; De Crevoisier, Renaud; Acosta, Oscar
2014-01-01
Accurate segmentation of the prostate and organs at risk in computed tomography (CT) images is a crucial step for radiotherapy (RT) planning. Manual segmentation, as performed nowadays, is a time consuming process and prone to errors due to the a high intra- and inter-expert variability. This paper introduces a new automatic method for prostate, rectum and bladder segmentation in planning CT using a geometrical shape model under a Bayesian framework. A set of prior organ shapes are first built by applying Principal Component Analysis (PCA) to a population of manually delineated CT images. Then, for a given individual, the most similar shape is obtained by mapping a set of multi-scale edge observations to the space of organs with a customized likelihood function. Finally, the selected shape is locally deformed to adjust the edges of each organ. Experiments were performed with real data from a population of 116 patients treated for prostate cancer. The data set was split in training and test groups, with 30 and 86 patients, respectively. Results show that the method produces competitive segmentations w.r.t standard methods (Averaged Dice = 0.91 for prostate, 0.94 for bladder, 0.89 for Rectum) and outperforms the majority-vote multi-atlas approaches (using rigid registration, free-form deformation (FFD) and the demons algorithm) PMID:24594798
Cho, Changsoon; Lee, Jung-Yong
2013-03-11
An efficient light trapping scheme is a key to enhancing the power conversion efficiency (PCE) of thin-film photovoltaic (PV) cells by compensating for the insufficient light absorption. To handle optical components from nano-scale to micro-scale seamlessly, a multi-scale optical simulation is carefully designed in this study and is used to qualitatively analyze the light trapping performances of a micro lens array (MLA), a V-shaped configuration, and the newly proposed scheme, which is termed a double parabolic trapper (DPT) according to both daily and annual movement of the sun. DPT has the potential to enhance the PCE significantly, from 5.9% to 8.9%, for PCDTBT:PC(70)BM-based polymer solar cells by perfectly trapping the incident light between two parabolic PV cells.
Shape forming by thermal expansion mismatch and shape memory locking in polymer/elastomer laminates
Yuan, Chao; Ding, Zhen; Wang, T. J.; Dunn, Martin L.; Qi, H. Jerry
2017-10-01
This paper studies a novel method to fabricate three-dimensional (3D) structure from 2D thermo-responsive shape memory polymer (SMP)/elastomer bilayer laminate. In this method, the shape change is actuated by the thermal mismatch strain between the SMP and the elastomer layers upon heating. However, the glass transition behavior of the SMP locks the material into a new 3D shape that is stable even upon cooling. Therefore, the second shape becomes a new permanent shape of the laminate. A theoretical model that accounts for the temperature-dependent thermomechanical behavior of the SMP material and thermal mismatch strain between the two layers is developed to better understand the underlying physics. Model predictions and experiments show good agreement and indicate that the theoretical model can well predict the bending behavior of the bilayer laminate. The model is then used in the optimal design of geometrical configuration and material selection. The latter also illustrates the requirement of thermomechanical behaviors of the SMP to lock the shape. Based on the fundamental understandings, several self-folding structures are demonstrated by the bilayer laminate design.
Geometric modeling and analysis of large latticed surfaces
Nayfeh, A. H.; Hefzy, M. S.
1980-01-01
The application of geometrical schemes, similar to geodesic domes, to large spherical antenna reflectors was investigated. The shape and size of flat segmented latticed surfaces which approximate general shells of revolution, and in particular spherical and paraboloidal reflective surfaces, were determined. The extensive mathematical and computational geometric analyses of the reflector resulted in the development of a general purpose computer program capable of generating the complete design parameters of the dish. The program also includes a graphical self contained subroutine for graphic display of the required design.
Directory of Open Access Journals (Sweden)
Charistos Leonidas
2014-06-01
Full Text Available Honey bees collected from 32 different localities in Greece were studied based on the geometric morphometrics approach using the coordinates of 19 landmarks located at wing vein intersections. Procrustes analysis, principal component analysis, and Canonical variate analysis (CVA detected population variability among the studied samples. According to the Principal component analysis (PCA of pooled data from each locality, the most differentiated populations were the populations from the Aegean island localities Astypalaia, Chios, and Kythira. However, the populations with the most distant according to the canonical variate analysis performed on all measurements were the populations from Heraklion and Chania (both from Crete island. These results can be used as a starting point for the use of geometric morphometrics in the discrimination of honey bee populations in Greece and the establishment of conservation areas for local honey bee populations.
Methods and apparatuses for signaling with geometric constellations
Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)
2012-01-01
Communication systems are described that use signal constellations, which have unequally spaced (i.e. geometrically shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.
Oscillating Filaments. I. Oscillation and Geometrical Fragmentation
Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas
2017-01-01
We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.
Product Configuration Systems and Productivity
DEFF Research Database (Denmark)
Pedersen, Jørgen Lindgaard; Edwards, Kasper
2004-01-01
Twelve companies have been interviewed with the purpose to get information about technical, economic and organisational matters in respect of Product Configuration Systems (PCS).Combinations of qualitative interviews and quantitative scoring have been used in ranking expected and realized results...... from implementing PCS. The three highest aggregated scoring expected benefits are: 1)improved quality in specifications, 2)lower turnaround time, 3)less resource intensity.......Twelve companies have been interviewed with the purpose to get information about technical, economic and organisational matters in respect of Product Configuration Systems (PCS).Combinations of qualitative interviews and quantitative scoring have been used in ranking expected and realized results...
Pühringer, Gerald; Jakoby, Bernhard
2017-05-01
We evaluate a recently devised design of vertical-cavity enhanced resonant thermal emitter (VERTE) regarding stability to fabrication tolerances of PVD layer deposition techniques. Such an emitter achieves narrowband and coherent thermal emission and is composed of an multilayer stack of dielectric layers (silicon and silica) on top of a reflective metal (silver) structure. The silica layer above the metal acts as a vertical cavity enhancing the electromagnetic field between the reflective metal and the dielectric stack forming a Bragg mirror (1-D photonic crystal). In our previous work, we identified several suitable five-layer-stack configurations, which considered several features and limitations of a real-world device, such as temperature dependence of the materials, fabrication constraints or unwanted emission modes. However, the emission characteristics are very sensitive to the geometrical and optical properties of the material. In order to examine this behaviour, a Monte-Carlo algorithm was used to apply a Gauss-distributed error in depth (relative the unperturbed layer thickness) for every individual layer. The robustness of the emission properties against fabrication errors were evaluated and analyzed by significant statistical quantities. As expected, the main issue compromising the emission properties is a deviation of the resonance wavelength in relation to the initial target resonance wavelength of the unperturbed configuration. Interestingly, configurations with larger average layer thicknesses and therefore with larger absolute thickness deviations did not exhibit a larger variance of the emission wavelength. Instead, the variance slightly decreased or remained constant. A similar result was obtained for increasing the number of dielectric layers. In contrast, the peak emissivity (at normal incidence) was significantly influenced by the average layer depth of a configuration. Also, the effect of broadening of the spectral emittance curve due to
Vignon, Matthias; Sasal, Pierre
2010-06-01
The sclerotized attachment organ of monogeneans has been widely used to address fundamental questions in ecology and evolution. However, traditional morphometric techniques appear to be partially inadequate and non-optimal. Traditional linear measurements mainly provide information on the size of sclerites but provide very little information, if any, on their shape. The shape of sclerites is indeed virtually unexplored and its implication for ecological and evolutionary processes remains to be analyzed. This study aims to both introduce and illustrate the use of geometric morphometrics in order to study sclerites of monogeneans in a biogeographic context. To do this, we investigated morphological variation patterns among four populations from the Pacific Ocean and six monogenean species through traditional and geometric morphometric techniques. Unlike the traditional method, the geometric morphometric method yielded a high percentage of individuals correctly classified to the four populations, providing strong evidence for phenotypic variability, divergence and local adaptation among islands without evolutionary constraint. Moreover, the traditional method also resulted in inconsistent interpretations of shape variations. This study highlighted the limitations that may arise when using traditional morphometric techniques and emphasizes that considerable information about the shape of sclerotized haptoral parts is added by using geometric morphometrics. Given the prominent taxonomic, ecological and evolutionary role of the haptor for characterizing monogeneans, we ultimately discuss the potential broad use of geometric morphometrics in a wide variety of ecological and evolutionary contexts. This powerful approach might allow a more robust estimation of the extent to which traditional evolutionary theories based on size of sclerites are congruent with their shape.
Concepts and Figures in Geometric Reasoning.
Fischbein, Efraim; Nachlieli, Talli
1998-01-01
Opens with the theoretical construct of figural concepts. Argues that geometrical figures are characterized by both conceptual and sensorial properties. Investigates the effects of interaction between conceptual and figural components. Contains 19 references. (DDR)
Geometric continuum mechanics and induced beam theories
R Eugster, Simon
2015-01-01
This research monograph discusses novel approaches to geometric continuum mechanics and introduces beams as constraint continuous bodies. In the coordinate free and metric independent geometric formulation of continuum mechanics as well as for beam theories, the principle of virtual work serves as the fundamental principle of mechanics. Based on the perception of analytical mechanics that forces of a mechanical system are defined as dual quantities to the kinematical description, the virtual work approach is a systematic way to treat arbitrary mechanical systems. Whereas this methodology is very convenient to formulate induced beam theories, it is essential in geometric continuum mechanics when the assumptions on the physical space are relaxed and the space is modeled as a smooth manifold. The book addresses researcher and graduate students in engineering and mathematics interested in recent developments of a geometric formulation of continuum mechanics and a hierarchical development of induced beam theories.
GEODSS Present Configuration and Potential
2014-06-28
1. REPORT DATE 28 JUN 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE GEODSS Present Configuration and...provides improved resolution and radiometric throughput at low elevation angles versus a single fisheye optical strategy. Both optical systems are
Miranda, Alexandre F; Sampaio, Francisco J B
2014-06-01
A surgical approach with plaque incision and graft (PIG) to correct Peyronie's disease is the best method for complex, large deviations. However, the geometric and mechanical consequences of this intervention are poorly understood. The aim of this study was to analyze the geometric and mechanical consequences of PIG on penile straighten surgery. A tridimensional penile simile model with a curvature of 85° was created to test all of the most common PIG techniques. PIG with double-Y, H-shape, and Egydio techniques were used to rectify the curved penile model. The results that differed from a rectified cylinder shape were highlighted. All of the analyzed techniques created a geometric distortion that could be linked to poor surgical results. We suggest a new technique to resolve these abnormalities. Current techniques designed to correct penile deviation using PIG present geometric and mechanical imperfections with potential consequences to the postoperative success rate. The new technique proposed in this report could be a possible solution to solve the geometric distortion caused by PIG. © 2014 International Society for Sexual Medicine.
Geometrical control of ionic current rectification in a configurable nanofluidic diode.
Alibakhshi, Mohammad Amin; Liu, Binqi; Xu, Zhiping; Duan, Chuanhua
2016-09-01
Control of ionic current in a nanofluidic system and development of the elements analogous to electrical circuits have been the subject of theoretical and experimental investigations over the past decade. Here, we theoretically and experimentally explore a new technique for rectification of ionic current using asymmetric 2D nanochannels. These nanochannels have a rectangular cross section and a stepped structure consisting of a shallow and a deep side. Control of height and length of each side enables us to obtain optimum rectification at each ionic strength. A 1D model based on the Poisson-Nernst-Planck equation is derived and validated against the full 2D numerical solution, and a nondimensional concentration is presented as a function of nanochannel dimensions, surface charge, and the electrolyte concentration that summarizes the rectification behavior of such geometries. The rectification factor reaches a maximum at certain electrolyte concentration predicted by this nondimensional number and decays away from it. This method of fabrication and control of a nanofluidic diode does not require modification of the surface charge and facilitates the integration with lab-on-a-chip fluidic circuits. Experimental results obtained from the stepped nanochannels are in good agreement with the 1D theoretical model.
Drake, Abby Grace
2011-01-01
Heterochrony is an evolutionary mechanism that generates diversity via perturbations of the rate or timing of development that requires very little genetic innovation. As such, heterochrony is thought to be a common evolutionary mechanism in the generation of diversity. Previous research has suggested that dogs evolved via heterochrony and are paedomorphic wolves. This study uses three-dimensional landmark-based coordinate data to investigate heterochronic patterns within the skull morphology of the domestic dog. A total of 677 adult dogs representing 106 different breeds were measured and compared with an ontogenetic series of 401 wolves. Geometric morphometric analysis reveals that the cranial shape of none of the modern breeds of dogs resembles the cranial shapes of adult or juvenile wolves. In addition, investigations of regional heterochrony in the face and neurocranium also reject the hypothesis of heterochrony. Throughout wolf cranial development the position of the face and the neurocranium remain in the same plane. Dogs, however, have a de novo cranial flexion in which the palate is tilted dorsally in brachycephalic and mesaticephalic breeds or tilted ventrally in dolichocephalic and down-face breeds. Dogs have evolved very rapidly into an incredibly morphologically diverse species with very little genetic variation. However, the genetic alterations to dog cranial development that have produced this vast range of phylogenetically novel skull shapes do not coincide with the expectations of the heterochronic model. Dogs are not paedomorphic wolves.
Directory of Open Access Journals (Sweden)
Mohd. Saqib
2016-09-01
Full Text Available In this study, an Artificial Neural Networks (ANN model is built and verified for quick estimation of the structural parameter obtained for a concrete gravity dam section due to seismic excitation. The database of numerous inputs and outputs obtained through Abaqus which are further converted into dimensionless forms in the statistical software (MATLAB to build the ANN model. The developed model can be used for accurate estimation of this parameter. The results showed an excellent capability of the model to predict the outputs with high accuracy and reduced computational time.
Energy Technology Data Exchange (ETDEWEB)
Rimza, Sandeep, E-mail: sandeepr@ipr.res.in [Divertor and First Wall Technology Development Division, Institute for Plasma Research (IPR), Bhat – 382428, Gandhinagar, Gujarat (India); Satpathy, Kamalakanta, E-mail: satpathy@ipr.res.in [Divertor and First Wall Technology Development Division, Institute for Plasma Research (IPR), Bhat – 382428, Gandhinagar, Gujarat (India); Khirwadkar, Samir, E-mail: sameer@ipr.res.in [Divertor and First Wall Technology Development Division, Institute for Plasma Research (IPR), Bhat – 382428, Gandhinagar, Gujarat (India); Velusamy, Karupanna, E-mail: kvelu@igcar.gov.in [Mechanics and Hydraulics Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India)
2015-11-15
Highlights: • Effect of design variables in enhancing heat removal potential with pumping power assessed. • The optimization objective is to minimize the thimble temperature. • Investigation of optimum design parameters for various Reynolds number. • Practicability of the optimum designs is verified through structural analysis. • Benchmark validation of divertor finger mock-up against in-house experiment and good agreement is achieved. - Abstract: Cooling of fusion reactor divertor by helium is widely accepted due to its chemical and neutronic inertness and superior safety aspect. However, its poor thermo physical characteristics need high pressure to remove large heat flux encountered in fusion power plant (DEMO). In the perspective of DEMO, it is desirable to explore efficient cooling technology for divertor that can handle high heat flux. Toward this, a novel sectorial extended surface (SES) was proposed by the authors Rimza et al. (2014) [2]. The present work focuses on design optimization of divertor finger mock-up with SES to enhance the thermal hydraulic performance. The maximum thimble temperature is considered as the vital design constraint. Various non-dimensional design variables, viz., relative pitch, thickness, jet diameter, the ratio of height of SES to jet diameter and circumferential position of the SES are considered for the present optimization study. The effects of design variables on thermal performance of the divertor are evaluated in the Reynolds number (Re) range of 7.5 × 10{sup 4}–1.2 × 10{sup 5}. The analysis reveals that, the heat transfer performance of divertor finger mock-up with SES is improved for two optimum designs having relative pitch and thickness of 0.30 and 0.56, respectively. Also, it is observed that finger mock-up heat sink with SES performs better, when the ratio of SES height to jet diameter, reduces to 0.75 at the cost of marginally higher pumping power. The effects of jet diameter and circumferential
Differential Drag Analysis to Infer the Geometrical Configuration of a Cubesat
Bussy-Virat, C.; Ridley, A. J.; Cutler, J.; Sharma, S.; Judd, E.
2016-12-01
On May 16th, 2016, the Miniature X-ray Solar Spectrometer (MinXSS) and the CubeSat investigating Atmospheric Density Response to Extreme driving (CADRE) were deployed from the International Space Station. While communication with MinXSS was quickly established, it has been impossible to interact with CADRE thus far. A likely reason could be that its solar panels did not open, preventing the antenna from fully functioning and eliminating communication with the ground stations. An orbit propagator that was developed for mission design and analysis was used to model the trajectories of the satellites. By comparing the drag accelerations on the two CubeSats, we are attempting to infer the number of solar panels that CADRE deployed. Ensemble simulations allow the modeling of uncertainties on its attitude, as it is likely to tumble if no solar panel was deployed. This technique introduces many challenges, as there are many unknowns, including the drag coefficient, the attitude, and the thermospheric density. We present results of this study, as well as these challenges that were encountered.
Geometric modeling of subcellular structures, organelles, and multiprotein complexes
Feng, Xin; Xia, Kelin; Tong, Yiying; Wei, Guo-Wei
2013-01-01
SUMMARY Recently, the structure, function, stability, and dynamics of subcellular structures, organelles, and multi-protein complexes have emerged as a leading interest in structural biology. Geometric modeling not only provides visualizations of shapes for large biomolecular complexes but also fills the gap between structural information and theoretical modeling, and enables the understanding of function, stability, and dynamics. This paper introduces a suite of computational tools for volumetric data processing, information extraction, surface mesh rendering, geometric measurement, and curvature estimation of biomolecular complexes. Particular emphasis is given to the modeling of cryo-electron microscopy data. Lagrangian-triangle meshes are employed for the surface presentation. On the basis of this representation, algorithms are developed for surface area and surface-enclosed volume calculation, and curvature estimation. Methods for volumetric meshing have also been presented. Because the technological development in computer science and mathematics has led to multiple choices at each stage of the geometric modeling, we discuss the rationales in the design and selection of various algorithms. Analytical models are designed to test the computational accuracy and convergence of proposed algorithms. Finally, we select a set of six cryo-electron microscopy data representing typical subcellular complexes to demonstrate the efficacy of the proposed algorithms in handling biomolecular surfaces and explore their capability of geometric characterization of binding targets. This paper offers a comprehensive protocol for the geometric modeling of subcellular structures, organelles, and multiprotein complexes. PMID:23212797
Free-form geometric modeling by integrating parametric and implicit PDEs.
Du, Haixia; Qin, Hong
2007-01-01
Parametric PDE techniques, which use partial differential equations (PDEs) defined over a 2D or 3D parametric domain to model graphical objects and processes, can unify geometric attributes and functional constraints of the models. PDEs can also model implicit shapes defined by level sets of scalar intensity fields. In this paper, we present an approach that integrates parametric and implicit trivariate PDEs to define geometric solid models containing both geometric information and intensity distribution subject to flexible boundary conditions. The integrated formulation of second-order or fourth-order elliptic PDEs permits designers to manipulate PDE objects of complex geometry and/or arbitrary topology through direct sculpting and free-form modeling. We developed a PDE-based geometric modeling system for shape design and manipulation of PDE objects. The integration of implicit PDEs with parametric geometry offers more general and arbitrary shape blending and free-form modeling for objects with intensity attributes than pure geometric models.
DEFF Research Database (Denmark)
Hirst, Andrew G.; Glazier, Douglas S.; Atkinson, David
2014-01-01
the size dependence of metabolism is derived from material transport across external surfaces, or through internal resource-transport networks. We show that when body shape changes during growth, these models make opposing predictions. These models are tested using pelagic invertebrates, because...... these animals exhibit highly variable intraspecific scaling relationships for metabolic rate and body shape. Metabolic scaling slopes of diverse integument-breathing species were significantly positively correlated with degree of body flattening or elongation during ontogeny, as expected from surface area...
Bogner, R. S.; Farris, C. D. (Inventor)
1974-01-01
An improved silver-zinc battery particularly suited for use in an environment where battery operation is subjected to multiple charge/discharge cycling over extended periods is described. The battery seperator system, containing a highly absorbent material continguous with the surfaces of the plates and multiple semi-permeable membranes interposed between the plates, is also characterized.
Real-time geometric scene estimation for RGBD images using a 3D box shape grammar
Willis, Andrew R.; Brink, Kevin M.
2016-06-01
This article describes a novel real-time algorithm for the purpose of extracting box-like structures from RGBD image data. In contrast to conventional approaches, the proposed algorithm includes two novel attributes: (1) it divides the geometric estimation procedure into subroutines having atomic incremental computational costs, and (2) it uses a generative "Block World" perceptual model that infers both concave and convex box elements from detection of primitive box substructures. The end result is an efficient geometry processing engine suitable for use in real-time embedded systems such as those on an UAVs where it is intended to be an integral component for robotic navigation and mapping applications.
[A geometrical analysis of the shape of the response surface in ecologico-toxicologic experiments].
Maksimov, V N; Kadomtsev, S V; Korsak, M N; Lifshits, A V
1989-01-01
A new method of working up results of factorial toxicological experiments is put forward and illustrated by a number of examples. It is based on the profound comparison of values of reactions as consequences of toxic influence and aimed at revealing the combinations of toxicant concentrations that break the monotonous character of a surface which graphically depicts the effect of pollutants. The geometrical analysis allows us to have a new vision of numerous results of factorial experiments, gives some complimentary possibilities for quantitative evaluation of impact of pollutants by mean of surface diagrams and for experimental assessment of environmental parameters of natural communities.
Denu, Garuma Abdisa; Liu, Zongchen; Fu, Jiao; Wang, Hongxing
2017-01-01
We report the effect of geometrical shape of diamond nanowire on its mechanical properties. Finite element modeling using COMSOL Multiphysics software is used to simulate various diamond nanowire with circular, square, rectangular, hexagonal and triangular cross-sections. A bending test under concentrated load applied at one of the free ends is simulated using FEM. The force response of the nanowire under different loading is studied for the various cross-sections. The dimensions of each cross-section is chosen so that material properties such as Young's modulus can be kept constant for comparison in all the cross-sections. It is found out that the bending capability of a triangular nanowire is higher compared to other cross-sections due to its lowest second moment. Circular and hexagonal cross-section show highest stiffness. The study of mechanical property of diamond nanowires is useful for optimal nanomechanical designs where the effect of cross-section has to be taken into account.
Product Configuration Systems and Productivity
DEFF Research Database (Denmark)
Pedersen, Jørgen Lindgaard; Edwards, Kasper
2004-01-01
Twelve companies have been interviewed with the purpose to get information about technical, economic and organisational matters in respect of Product Configuration Systems (PCS).Combinations of qualitative interviews and quantitative scoring have been used in ranking expected and realized results...... from implementing PCS. The three highest aggregated scoring expected benefits are: 1)improved quality in specifications, 2)lower turnaround time, 3)less resource intensity....
Reiss, Katie L; Bonnan, Matthew F
2010-07-01
The shark heterocercal caudal fin and its contribution to locomotion are of interest to biologists and paleontologists. Current hydrodynamic data show that the stiff dorsal lobe leads the ventral lobe, both lobes of the tail are synchronized during propulsion, and tail shape reflects its overall locomotor function. Given the difficulties surrounding the analysis of shark caudal fins in vivo, little is known about changes in tail shape related to ontogeny and sex in sharks. A quantifiable analysis of caudal fin shape may provide an acceptable proxy for inferring gross functional morphology where direct testing is difficult or impossible. We examined ontogenetic and sex-related shape changes in the caudal fins of 115 Squalus acanthias museum specimens, to test the hypothesis that significant shape changes in the caudal fin shape occur with increasing size and between the sexes. Using linear and geometric morphometrics, we examined caudal shape changes within the context of current hydrodynamic models. We found no statistically significant linear or shape difference between sexes, and near-isometric scaling trends for caudal dimensions. These results suggest that lift and thrust increase linearly with size and caudal span. Thin-plate splines results showed a significant allometric shape change associated with size and caudal span: the dorsal lobe elongates and narrows, whereas the ventral lobe broadens and expands ventrally. Our data suggest a combination of caudal fin morphology with other body morphology aspects, would refine, and better elucidate the hydrodynamic factors (if any) that underlie the significant shape changes we report here for S. acanthias.
A Newtonian interpretation of configurational forces on dislocations and cracks
Ballarini, Roberto; Royer-Carfagni, Gianni
2016-10-01
Configurational forces are fundamental concepts in the description of the motion of dislocations, cracks and other defects that introduce singularities within the solid state. They are defined by considering variations in energies associated with the movement of such defects, and are therefore different from the classical forces that enter the balance laws of classical Newtonian mechanics. Here, it is demonstrated how a configurational force can be viewed as the resultant of the (Newtonian) contact forces acting on the perturbed shape of an object of substance equivalent to the defect, and evaluated in the limit of the shape being restored to the primitive configuration. The expressions for the configurational forces on the paradigmatic examples of cracks and dislocations are in agreement with those determined using classical variational arguments. This finding opens a new prospective in the use of configurational forces by permitting their physical and intuitive visualization.
Introduction to Dynamical Systems and Geometric Mechanics
Maruskin, Jared M.
2012-01-01
Introduction to Dynamical Systems and Geometric Mechanics provides a comprehensive tour of two fields that are intimately entwined: dynamical systems is the study of the behavior of physical systems that may be described by a set of nonlinear first-order ordinary differential equations in Euclidean space, whereas geometric mechanics explores similar systems that instead evolve on differentiable manifolds. In the study of geometric mechanics, however, additional geometric structures are often present, since such systems arise from the laws of nature that govern the motions of particles, bodies, and even galaxies. In the first part of the text, we discuss linearization and stability of trajectories and fixed points, invariant manifold theory, periodic orbits, PoincarÃ© maps, Floquet theory, the PoincarÃ©-Bendixson theorem, bifurcations, and chaos. The second part of the text begins with a self-contained chapter on differential geometry that introduces notions of manifolds, mappings, vector fields, the Jacobi-Lie bracket, and differential forms. The final chapters cover Lagrangian and Hamiltonian mechanics from a modern geometric perspective, mechanics on Lie groups, and nonholonomic mechanics via both moving frames and fiber bundle decompositions. The text can be reasonably digested in a single-semester introductory graduate-level course. Each chapter concludes with an application that can serve as a springboard project for further investigation or in-class discussion.
Dynamics and Control of Humanoid Robots: A Geometrical Approach
Ivancevic, Vladimir G
2011-01-01
his paper reviews modern geometrical dynamics and control of humanoid robots. This general Lagrangian and Hamiltonian formalism starts with a proper definition of humanoid's configuration manifold, which is a set of all robot's active joint angles. Based on the `covariant force law', the general humanoid's dynamics and control are developed. Autonomous Lagrangian dynamics is formulated on the associated `humanoid velocity phase space', while autonomous Hamiltonian dynamics is formulated on the associated `humanoid momentum phase space'. Neural-like hierarchical humanoid control naturally follows this geometrical prescription. This purely rotational and autonomous dynamics and control is then generalized into the framework of modern non-autonomous biomechanics, defining the Hamiltonian fitness function. The paper concludes with several simulation examples. Keywords: Humanoid robots, Lagrangian and Hamiltonian formalisms, neural-like humanoid control, time-dependent biodynamics
Nardin, W.; Larsen, L.; Fagherazzi, S.; Wiberg, P.
2016-12-01
During recent decades coastlines have experienced unprecedented morphological modifications caused by sea level rise, subsidence, extreme events like hurricanes and a reduction of sediment supply. Most previous modeling studies on flow-vegetation-sediment interactions have focused on one specific vegetated community, but we lack a general understanding of the conditions that lead to the emergence of multiple vegetation species feedbacks. Using a modeling approach, this study generates new understanding of how sediment transport and ecogeomorphic interactions involving water flow, sediment, and vegetation influence landscape in coastal wetlands. The broad goal of this project is to distinguish between the influence of saltmarsh and seagrass experiencing different feedback and forcing on sediment deposition. We focus our study on the Virginia Coast Reserve LTER site, where we apply numerical modeling (Delft-3D) and subsequent analyses to determine the sets of environmental conditions under which eco-geomorphological feedbacks drive the wetland system to different landscape structures. Our numerical results show that salt marsh and seagrass reduce the volume of water in a shallow coastal bay up to 15% during each tidal cycle when compared to the case without vegetation. From a morphodynamic point of view, our study reveals the important role that vegetation plays in altering water residence times and increasing sedimentation in the bay. Vegetation also affects bay geomorphology by locally reducing bed shear stress and hence increasing sediment deposition. By evaluating alternative densities, heights and spatial distributions of seagrass and salt marsh, we develop different future projections that should be considered in the design of restoration strategies in shallow coastal bays such as those in the Virginia Coast Reserve.
Spherical projections and liftings in geometric tomography
DEFF Research Database (Denmark)
Goodey, Paul; Kiderlen, Markus; Weil, Wolfgang
2011-01-01
We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies and to rad......We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies...... and to radial functions of star bodies. We then investigate averages of lifted projections and show that they correspond to self-adjoint intertwining operators. We obtain formulas for the eigenvalues of these operators and use them to ascertain circumstances under which tomographic measurements determine...... the original bodies. This approach via mean lifted projections leads us to some unexpected relationships between seemingly disparate geometric constructions....
Multiple structural alignment and core detection by geometric hashing.
Leibowitz, N; Fligelman, Z Y; Nussinov, R; Wolfson, H J
1999-01-01
A Multiple Structural Alignment algorithm is presented. The algorithm accepts an ensemble of protein structures and finds the largest substructure (core) of C alpha atoms whose geometric configuration appear in all the molecules of the ensemble (core). Both the detection of this core and the resulting structural alignment are done simultaneously. Other large enough multistructural superimpositions are detected as well. Our method is based on the Geometric Hashing paradigm and a superimposition clustering technique which represents superimpositions by sets of matching atoms. The algorithm proved to be efficient on real data in a series of experiments. The same method can be applied to any ensemble of molecules (not necessarily proteins) since our basic technique is sequence order independent.
Workshop on Topology and Geometric Group Theory
Fowler, James; Lafont, Jean-Francois; Leary, Ian
2016-01-01
This book presents articles at the interface of two active areas of research: classical topology and the relatively new field of geometric group theory. It includes two long survey articles, one on proofs of the Farrell–Jones conjectures, and the other on ends of spaces and groups. In 2010–2011, Ohio State University (OSU) hosted a special year in topology and geometric group theory. Over the course of the year, there were seminars, workshops, short weekend conferences, and a major conference out of which this book resulted. Four other research articles complement these surveys, making this book ideal for graduate students and established mathematicians interested in entering this area of research.
A simple geometrical model describing shapes of soap films suspended on two rings
Herrmann, Felix J.; Kilvington, Charles D.; Wildenberg, Rebekah L.; Camacho, Franco E.; Walecki, Wojciech J.; Walecki, Peter S.; Walecki, Eve S.
2016-09-01
We measured and analysed the stability of two types of soap films suspended on two rings using the simple conical frusta-based model, where we use common definition of conical frustum as a portion of a cone that lies between two parallel planes cutting it. Using frusta-based we reproduced very well-known results for catenoid surfaces with and without a central disk. We present for the first time a simple conical frusta based spreadsheet model of the soap surface. This very simple, elementary, geometrical model produces results surprisingly well matching the experimental data and known exact analytical solutions. The experiment and the spreadsheet model can be used as a powerful teaching tool for pre-calculus and geometry students.
MM Algorithms for Geometric and Signomial Programming.
Lange, Kenneth; Zhou, Hua
2014-02-01
This paper derives new algorithms for signomial programming, a generalization of geometric programming. The algorithms are based on a generic principle for optimization called the MM algorithm. In this setting, one can apply the geometric-arithmetic mean inequality and a supporting hyperplane inequality to create a surrogate function with parameters separated. Thus, unconstrained signomial programming reduces to a sequence of one-dimensional minimization problems. Simple examples demonstrate that the MM algorithm derived can converge to a boundary point or to one point of a continuum of minimum points. Conditions under which the minimum point is unique or occurs in the interior of parameter space are proved for geometric programming. Convergence to an interior point occurs at a linear rate. Finally, the MM framework easily accommodates equality and inequality constraints of signomial type. For the most important special case, constrained quadratic programming, the MM algorithm involves very simple updates.
Classical Light Beams and Geometric Phases
Mukunda, N; Simon, R
2013-01-01
We present a study of geometric phases in classical wave and polarisation optics using the basic mathematical framework of quantum mechanics. Important physical situations taken from scalar wave optics, pure polarisation optics, and the behaviour of polarisation in the eikonal or ray limit of Maxwell's equations in a transparent medium are considered. The case of a beam of light whose propagation direction and polarisation state are both subject to change is dealt with, attention being paid to the validity of Maxwell's equations at all stages. Global topological aspects of the space of all propagation directions are discussed using elementary group theoretical ideas, and the effects on geometric phases are elucidated.
The effect of photometric and geometric context on photometric and geometric lightness effects.
Lee, Thomas Y; Brainard, David H
2014-01-24
We measured the lightness of probe tabs embedded at different orientations in various contextual images presented on a computer-controlled stereo display. Two background context planes met along a horizontal roof-like ridge. Each plane was a graphic rendering of a set of achromatic surfaces with the simulated illumination for each plane controlled independently. Photometric context was varied by changing the difference in simulated illumination intensity between the two background planes. Geometric context was varied by changing the angle between them. We parsed the data into separate photometric effects and geometric effects. For fixed geometry, varying photometric context led to linear changes in both the photometric and geometric effects. Varying geometric context did not produce a statistically reliable change in either the photometric or geometric effects.
Adiabatic geometric phases and response functions
Jain, S R; Jain, Sudhir R.; Pati, Arun K.
1998-01-01
Treating a many-body Fermi system in terms of a single particle in a deforming mean field. We relate adiabatic geometric phase to susceptibility for the noncyclic case, and to its derivative for the cyclic case. Employing the semiclassical expression of susceptibility, the expression for geometric phase for chaotic quantum system immediately follows. Exploiting the well-known association of the absorptive part of susceptibility with dissipation, our relations may provide a quantum mechanical origin of the damping of collective excitations in Fermi systems.
Serenelli, Roberto
2004-12-01
This paper analyzes simple imaging configurations to scan a human body, suitable as passive or active millimetre-wave imaging systems for concealed weapon detection (CWD). The first cylindrical configuration allows a 360 degrees scan: N unphased diffraction-limited antennas each of size L are placed on a circular support surrounding the subject (allowing scanning in the horizontal plane with N non-overlapping independent beams), and this circle is mechanically displaced over the whole body height. An analytical formula gives the maximum obtainable spatial resolution for different dimensions of the circular scanning device and operating frequencies, and the number of receivers achieving this optimal resolution. Constraints to be taken into account are diffraction, the usable total length of the circle, and the full coverage by the N beams over the subject, which is modelled as a cylinder with variable radius, coaxial with the scanning circle. Numerical calculations of system resolution are shown for different operating microwave (MW) and millimetre-wave (MMW) frequencies; in order to study off-axis performances, situations where the subject is not coaxial with the scanning device are also considered. For the case of a parallelepiped to be imaged instead of a cylinder, a linear array configuration is analyzed similarly to the circular one. A theoretical study is carried out to design other curved arrays, filled with unphased diffraction-limited antennas, for the imaging of linear subjects with finer resolution. Finally, the application of such configurations is considered for the design of active imaging systems, and different system architectures are discussed.
Geometric Abstract Art and Public Health Data
Centers for Disease Control (CDC) Podcasts
2016-10-18
Dr. Salaam Semaan, a CDC behavioral scientist, discusses the similarities between geometric abstract art and public health data analysis. Created: 10/18/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID). Date Released: 10/18/2016.
Wooden Geometric Puzzles: Design and Hardness Proofs
Alt, H.; Bodlaender, H.L.; Kreveld, M.J. van; Rote, G.; Tel, G.
2007-01-01
We discuss some new geometric puzzles and the complexity of their extension to arbitrary sizes. For gate puzzles and two-layer puzzles we prove NP-completeness of solving them. Not only the solution of puzzles leads to interesting questions, but also puzzle design gives rise to interesting
Wooden Geometric Puzzles: Design and Hardness Proofs
Alt, H.; Bodlaender, H.L.; Kreveld, M.J. van; Rote, G.; Tel, G.
2008-01-01
We discuss some new geometric puzzles and the complexity of their extension to arbitrary sizes. For gate puzzles and two-layer puzzles we prove NP-completeness of solving them. Not only the solution of puzzles leads to interesting questions, but also puzzle design gives rise to interesting
Wooden Geometric Puzzles: Design and Hardness Proofs
Alt, H.; Bodlaender, H.L.; Kreveld, M.J. van; Rote, G.; Tel, G.
2007-01-01
We discuss some new geometric puzzles and the complexity of their extension to arbitrary sizes. For gate puzzles and two-layer puzzles we prove NP-completeness of solving them. Not only the solution of puzzles leads to interesting questions, but also puzzle design gives rise to interesting theoretic
Wooden Geometric Puzzles: Design and Hardness Proofs
Alt, H.; Bodlaender, H.L.; Kreveld, M.J. van; Rote, G.; Tel, G.
2008-01-01
We discuss some new geometric puzzles and the complexity of their extension to arbitrary sizes. For gate puzzles and two-layer puzzles we prove NP-completeness of solving them. Not only the solution of puzzles leads to interesting questions, but also puzzle design gives rise to interesting theoretic
Geometric foundation of spin and isospin
Hannibal, L
1996-01-01
Various theories of spinning particles are interpreted as realizing elements of an underlying geometric theory. Classical particles are described by trajectories on the Poincare group. Upon quantization an eleven-dimensional Kaluza-Klein type theory is obtained which incorporates spin and isospin in a local SL(2,C) x U(1) x SU(2) theory with broken U(1)x SU(2) part.
Saturation and geometrical scaling in small systems
Praszalowicz, Michal
2016-01-01
Saturation and geometrical scaling (GS) of gluon distributions are a consequence of the non-linear evolution equations of QCD. We argue that in pp GS holds for the inelastic cross-section rather than for the multiplicity distributions. We also discuss possible fluctuations of the proton saturation scale in pA collisions at the LHC.
Geometric and Texture Inpainting by Gibbs Sampling
DEFF Research Database (Denmark)
Gustafsson, David Karl John; Pedersen, Kim Steenstrup; Nielsen, Mads
2007-01-01
This paper discuss a method suitable for inpainting both large scale geometric structures and more stochastic texture components. Image inpainting concerns the problem of reconstructing the intensity contents inside regions of missing data. Common techniques for solving this problem are methods...
Toeplitz Quantization and Asymptotic Expansions: Geometric Construction
Directory of Open Access Journals (Sweden)
Miroslav Englis
2009-02-01
Full Text Available For a real symmetric domain G_R/K_R, with complexification G_C/K_C, we introduce the concept of ''star-restriction'' (a real analogue of the ''star-products'' for quantization of Kähler manifolds and give a geometric construction of the G_R-invariant differential operators yielding its asymptotic expansion.
Multiscale characterization and analysis of shapes
Prasad, Lakshman; Rao, Ramana
2002-01-01
An adaptive multiscale method approximates shapes with continuous or uniformly and densely sampled contours, with the purpose of sparsely and nonuniformly discretizing the boundaries of shapes at any prescribed resolution, while at the same time retaining the salient shape features at that resolution. In another aspect, a fundamental geometric filtering scheme using the Constrained Delaunay Triangulation (CDT) of polygonized shapes creates an efficient parsing of shapes into components that have semantic significance dependent only on the shapes' structure and not on their representations per se. A shape skeletonization process generalizes to sparsely discretized shapes, with the additional benefit of prunability to filter out irrelevant and morphologically insignificant features. The skeletal representation of characters of varying thickness and the elimination of insignificant and noisy spurs and branches from the skeleton greatly increases the robustness, reliability and recognition rates of character recognition algorithms.
Effects of imbalance and geometric error on precision grinding machines
Energy Technology Data Exchange (ETDEWEB)
Bibler, J.E.
1997-06-01
To study balancing in grinding, a simple mechanical system was examined. It was essential to study such a well-defined system, as opposed to a large, complex system such as a machining center. The use of a compact, well-defined system enabled easy quantification of the imbalance force input, its phase angle to any geometric decentering, and good understanding of the machine mode shapes. It is important to understand a simple system such as the one I examined given that imbalance is so intimately coupled to machine dynamics. It is possible to extend the results presented here to industrial machines, although that is not part of this work. In addition to the empirical testing, a simple mechanical system to look at how mode shapes, balance, and geometric error interplay to yield spindle error motion was modelled. The results of this model will be presented along with the results from a more global grinding model. The global model, presented at ASPE in November 1996, allows one to examine the effects of changing global machine parameters like stiffness and damping. This geometrically abstract, one-dimensional model will be presented to demonstrate the usefulness of an abstract approach for first-order understanding but it will not be the main focus of this thesis. 19 refs., 36 figs., 10 tables.
Chenglin, L.; Charpentier, R.R.
2010-01-01
The U.S. Geological Survey procedure for the estimation of the general form of the parent distribution requires that the parameters of the log-geometric distribution be calculated and analyzed for the sensitivity of these parameters to different conditions. In this study, we derive the shape factor of a log-geometric distribution from the ratio of frequencies between adjacent bins. The shape factor has a log straight-line relationship with the ratio of frequencies. Additionally, the calculation equations of a ratio of the mean size to the lower size-class boundary are deduced. For a specific log-geometric distribution, we find that the ratio of the mean size to the lower size-class boundary is the same. We apply our analysis to simulations based on oil and gas pool distributions from four petroleum systems of Alberta, Canada and four generated distributions. Each petroleum system in Alberta has a different shape factor. Generally, the shape factors in the four petroleum systems stabilize with the increase of discovered pool numbers. For a log-geometric distribution, the shape factor becomes stable when discovered pool numbers exceed 50 and the shape factor is influenced by the exploration efficiency when the exploration efficiency is less than 1. The simulation results show that calculated shape factors increase with those of the parent distributions, and undiscovered oil and gas resources estimated through the log-geometric distribution extrapolation are smaller than the actual values. ?? 2010 International Association for Mathematical Geology.
Dimensional, Geometrical, and Physical Constraints in Skull Growth
Weickenmeier, Johannes; Fischer, Cedric; Carter, Dennis; Kuhl, Ellen; Goriely, Alain
2017-06-01
After birth, the skull grows and remodels in close synchrony with the brain to allow for an increase in intracranial volume. Increase in skull area is provided primarily by bone accretion at the sutures. Additional remodeling, to allow for a change in curvatures, occurs by resorption on the inner surface of the bone plates and accretion on their outer surfaces. When a suture fuses too early, normal skull growth is disrupted, leading to a deformed final skull shape. The leading theory assumes that the main stimulus for skull growth is provided by mechanical stresses. Based on these ideas, we first discuss the dimensional, geometrical, and kinematic synchrony between brain, skull, and suture growth. Second, we present two mechanical models for skull growth that account for growth at the sutures and explain the various observed dysmorphologies. These models demonstrate the particular role of physical and geometrical constraints taking place in skull growth.
Heisenberg model and Rigged Configurations
Giri, Pulak Ranjan
2015-01-01
We show a correspondence of all the solutions of the spin-1/2 isotropic Heisenberg model for N=12 to the rigged configurations based on the comparison of the set of Takahashi quantum numbers in lexicographical order with the set of riggings of the rigged configurations in co-lexicographical order.
Code Organization and Configuration Management
Institute of Scientific and Technical Information of China (English)
J.P.Wellisch; I.Osborne; 等
2001-01-01
Industry experts are increasingly focusing on team productivity on team productivity as the key to success,the base of the team effort is the four-fold structure of software in terms of logical organisation,physical organisation,managerial organisation,and dynamical structure.We describe the ideas put into action within the CMS software for organising software into sub-systems and packages,and to establish configuration management in a multiproject environment.We use a structure that allows to maximise the independence of soft ware development in individual areas,and at the same time emphasises the overwhelming importance of the interdependencies between the packages and components in the system.We comment on release procedures,and describe the inter-relationship between release,development,integration,and testing.
Geometrical Models and Hadronic Radii
Zahra, Sarwat; Fazal-e-Aleem,; Hussain, Talib; Zafar, Abrar Ahmad; Tahir, Sohail Afzal
2015-01-01
By using electromagnetic form factors predicted by Generalized Chou Yang model (GCYM), we compute rms radii of several hadrons with varying strangeness content such as (Pion, Proton, Phi, Lambda0, Sigma+, Sigma- and Omega-). The computed radii are found quite consistent with the results of other models and experiments, indicating excellent predicting power of GCYM. The results indicate that rms radii decrease with increase in strangeness content, separately for mesons and baryons.
Linearization: Geometric, Complex, and Conditional
Directory of Open Access Journals (Sweden)
Asghar Qadir
2012-01-01
Full Text Available Lie symmetry analysis provides a systematic method of obtaining exact solutions of nonlinear (systems of differential equations, whether partial or ordinary. Of special interest is the procedure that Lie developed to transform scalar nonlinear second-order ordinary differential equations to linear form. Not much work was done in this direction to start with, but recently there have been various developments. Here, first the original work of Lie (and the early developments on it, and then more recent developments based on geometry and complex analysis, apart from Lie’s own method of algebra (namely, Lie group theory, are reviewed. It is relevant to mention that much of the work is not linearization but uses the base of linearization.
Institute of Scientific and Technical Information of China (English)
雷鸣
2015-01-01
预警机在未来战场上所面对目标的 RCS 越来越小，为了获得足够的作用距离，需要增加雷达的功率口径积，在载机功率资源一定的情况下，增大天线口径是最有效的方法。然而机载预警雷达天线口径受雷达罩外形尺寸及飞机总体气动构型等因素的限制，因此需要合理选择预警机总体气动构型并对雷达罩气动外形进行优化；通过合理的结构总体布局设计，有效利用雷达罩的气动外形，保证天线口径的最大化，文中就雷达罩气动外形选择以及雷达结构总体设计的相关问题进行探讨，可为预警机雷达结构总体设计提供参考。%The RCS of target faced by the early warning aircraft is getting smaller and smaller.It is re-quired to augment the power-aperture product for gaining the adequate detection range.It is the most effica-cious way to enlarge the antenna aperture when the power provided by the aircraft is limited.However,the antenna aperture of AEW radar is limited by the outline of the radome as well as the overall aerodynamic con-figuration of the aircraft.On the one hand,it is demanded to choose the overall aerodynamic configuration of the aircraft reasonably and to optimize the outline of the radome and make an effective use.On the other hand,it is demanded to design the overall layout of the equipment of antenna system precisely,so as to ensure the antenna aperture indexes.The related issues about the aerodynamic shape choice of radome and the overall structral design of AEW radar are discussed.
Langlands Program, Trace Formulas, and their Geometrization
Frenkel, Edward
2012-01-01
The Langlands Program relates Galois representations and automorphic representations of reductive algebraic groups. The trace formula is a powerful tool in the study of this connection and the Langlands Functoriality Conjecture. After giving an introduction to the Langlands Program and its geometric version, which applies to curves over finite fields and over the complex field, I give a survey of my recent joint work with Robert Langlands and Ngo Bao Chau (arXiv:1003.4578 and arXiv:1004.5323) on a new approach to proving the Functoriality Conjecture using the trace formulas, and on the geometrization of the trace formulas. In particular, I discuss the connection of the latter to the categorification of the Langlands correspondence.
Parts and Relations in Young Children's Shape-Based Object Recognition
Augustine, Elaine; Smith, Linda B.; Jones, Susan S.
2011-01-01
The ability to recognize common objects from sparse information about geometric shape emerges during the same period in which children learn object names and object categories. Hummel and Biederman's (1992) theory of object recognition proposes that the geometric shapes of objects have two components--geometric volumes representing major object…
Geometric Measure Theory and Minimal Surfaces
Bombieri, Enrico
2011-01-01
W.K. ALLARD: On the first variation of area and generalized mean curvature.- F.J. ALMGREN Jr.: Geometric measure theory and elliptic variational problems.- E. GIUSTI: Minimal surfaces with obstacles.- J. GUCKENHEIMER: Singularities in soap-bubble-like and soap-film-like surfaces.- D. KINDERLEHRER: The analyticity of the coincidence set in variational inequalities.- M. MIRANDA: Boundaries of Caciopoli sets in the calculus of variations.- L. PICCININI: De Giorgi's measure and thin obstacles.
Geometric problems in molecular biology and robotics.
Parsons, D; Canny, J
1994-01-01
Some of the geometric problems of interest to molecular biologists have macroscopic analogues in the field of robotics. Two examples of such analogies are those between protein docking and model-based perception, and between ring closure and inverse kinematics. Molecular dynamics simulation, too, has much in common with the study of robot dynamics. In this paper we give a brief survey of recent work on these and related problems.
Geometrical multiresolution adaptive transforms theory and applications
Lisowska, Agnieszka
2014-01-01
Modern image processing techniques are based on multiresolution geometrical methods of image representation. These methods are efficient in sparse approximation of digital images. There is a wide family of functions called simply ‘X-lets’, and these methods can be divided into two groups: the adaptive and the nonadaptive. This book is devoted to the adaptive methods of image approximation, especially to multismoothlets. Besides multismoothlets, several other new ideas are also covered. Current literature considers the black and white images with smooth horizon function as the model for sparse approximation but here, the class of blurred multihorizon is introduced, which is then used in the approximation of images with multiedges. Additionally, the semi-anisotropic model of multiedge representation, the introduction of the shift invariant multismoothlet transform and sliding multismoothlets are also covered. Geometrical Multiresolution Adaptive Transforms should be accessible to both mathematicians and com...
Geometrical product specifications. Datums and coordinate systems
Glukhov, V. I.; Ivleva, I. A.; Zlatkina, O. Y.
2017-06-01
The work is devoted to the relevant topic such as the technical products quality improvement due to the geometrical specifications accuracy. The research purpose is to ensure the quality indicators on the basis of the systematic approach to the values normalization and geometrical specifications accuracy in the workpiece coordinate systems in the process of design. To achieve the goal two tasks are completed such as the datum features classification according to the number of linear and angular freedom degrees constraints, called the datums informativeness, and the rectangular coordinate systems identification, materialized by workpiece datums sets. The datum features informativeness characterizes the datums functional purpose to limit product workpiece linear and angular degrees of freedom. The datum features informativeness numerically coincides with the kinematic pairs classes and couplings in mechanics. The datum features informativeness identifies the coordinate system without the location redundancy. Each coordinate plane of a rectangular coordinate system has different informativeness 3 + 2 + 1. Each coordinate axis also has different informativeness 4+2+Θ (zero). It is possible to establish the associated workpiece position with three linear and three angular coordinates relative to two axes with the informativeness 4 and 2. is higher, the more informativeness of the coordinate axis or a coordinate plane is, the higher is the linear and angular coordinates accuracy, the coordinate being plotted along the coordinate axis or plane. The systematic approach to the geometrical products specifications positioning in coordinate systems is the scientific basis for a natural transition to the functional dimensions of features position - coordinating dimensions and the size of the features form - feature dimensions of two measures: linear and angular ones. The products technical quality improving is possible due to the coordinate systems introduction materialized by
Crichton, Michael Lawrence; Muller, David Alexander; Depelsenaire, Alexandra Christina Isobel; Pearson, Frances Elizabeth; Wei, Jonathan; Coffey, Jacob; Zhang, Jin; Fernando, Germain J. P.; Kendall, Mark Anthony Fernance
2016-06-01
Micro-device use for vaccination has grown in the past decade, with the promise of ease-of-use, painless application, stable solid formulations and greater immune response generation. However, the designs of the highly immunogenic devices (e.g. the gene gun, Nanopatch or laser adjuvantation) require significant energy to enter the skin (30–90 mJ). Within this study, we explore a way to more effectively use energy for skin penetration and vaccination. These modifications change the Nanopatch projections from cylindrical/conical shapes with a density of 20,000 per cm2 to flat-shaped protrusions at 8,000 per cm2, whilst maintaining the surface area and volume that is placed within the skin. We show that this design results in more efficient surface crack initiations, allowing the energy to be more efficiently be deployed through the projections into the skin, with a significant overall increase in penetration depth (50%). Furthermore, we measured a significant increase in localized skin cell death (>2 fold), and resultant infiltrate of cells (monocytes and neutrophils). Using a commercial seasonal trivalent human influenza vaccine (Fluvax 2014), our new patch design resulted in an immune response equivalent to intramuscular injection with approximately 1000 fold less dose, while also being a practical device conceptually suited to widespread vaccination.
Crichton, Michael Lawrence; Muller, David Alexander; Depelsenaire, Alexandra Christina Isobel; Pearson, Frances Elizabeth; Wei, Jonathan; Coffey, Jacob; Zhang, Jin; Fernando, Germain J. P.; Kendall, Mark Anthony Fernance
2016-01-01
Micro-device use for vaccination has grown in the past decade, with the promise of ease-of-use, painless application, stable solid formulations and greater immune response generation. However, the designs of the highly immunogenic devices (e.g. the gene gun, Nanopatch or laser adjuvantation) require significant energy to enter the skin (30–90 mJ). Within this study, we explore a way to more effectively use energy for skin penetration and vaccination. These modifications change the Nanopatch projections from cylindrical/conical shapes with a density of 20,000 per cm2 to flat-shaped protrusions at 8,000 per cm2, whilst maintaining the surface area and volume that is placed within the skin. We show that this design results in more efficient surface crack initiations, allowing the energy to be more efficiently be deployed through the projections into the skin, with a significant overall increase in penetration depth (50%). Furthermore, we measured a significant increase in localized skin cell death (>2 fold), and resultant infiltrate of cells (monocytes and neutrophils). Using a commercial seasonal trivalent human influenza vaccine (Fluvax 2014), our new patch design resulted in an immune response equivalent to intramuscular injection with approximately 1000 fold less dose, while also being a practical device conceptually suited to widespread vaccination. PMID:27251567
Superatoms: Electronic and Geometric Effects on Reactivity.
Reber, Arthur C; Khanna, Shiv N
2017-02-21
The relative role of electronic and geometric effects on the stability of clusters has been a contentious topic for quite some time, with the focus on electronic structure generally gaining the upper hand. In this Account, we hope to demonstrate that both electronic shell filling and geometric shell filling are necessary concepts for an intuitive understanding of the reactivity of metal clusters. This work will focus on the reactivity of aluminum based clusters, although these concepts may be applied to clusters of different metals and ligand protected clusters. First we highlight the importance of electronic shell closure in the stability of metallic clusters. Quantum confinement in small compact metal clusters results in the bunching of quantum states that are reminiscent of the electronic shells in atoms. Clusters with closed electronic shells and large HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gaps have enhanced stability and reduced reactivity with O2 due to the need for the cluster to accommodate the spin of molecular oxygen during activation of the molecule. To intuitively understand the reactivity of clusters with protic species such as water and methanol, geometric effects are needed. Clusters with unsymmetrical structures and defects usually result in uneven charge distribution over the surface of the cluster, forming active sites. To reduce reactivity, these sites must be quenched. These concepts can also be applied to ligand protected clusters. Clusters with ligands that are balanced across the cluster are less reactive, while clusters with unbalanced ligands can result in induced active sites. Adatoms on the surface of a cluster that are bound to a ligand result in an activated adatom that reacts readily with protic species, offering a mechanism by which the defects will be etched off returning the cluster to a closed geometric shell. The goal of this Account is to argue that both geometric and electronic shell
Usefulness of a Rugby-shaped hohlraum in a Laser M'egaJoule (LMJ) 40-quad configuration
Malinie, G.; Vandenboomgaerde, M.; Bastian, J.; Galmiche, D.; Laffite, S.; Liberatore, S.
2007-11-01
The LMJ setup will consist of 60 quads in a 3-cone configuration, at angles 33.2^o, 49^o and 59.5^o. First ignition attempts in indirect drive are planned to be made on the way to the completion of the full facility, with only 40 quads in a 2-cone configuration, at angles 33.2^o and 49^o. By analytic considerations, we show that in a 40-quad configuration, the angular location of the hohlraum outer irradiating ring, as seen from the capsule, must be closer to the laser entrance hole than with the full LMJ. The use of a Rugby-shaped hohlraum instead of a cylinder therefore allows to keep a correct symmetry while reducing the wall surface, which improves the global energetic efficiency of the target. Simplified 2D numerical simulations of Rugby hohlraums are presented, achieving a yield of about 30 MJ with our 1.215 mm-radius, CH-uniform-ablator capsule. These results suggests this kind of hohlraum might be an interesting candidate for 40-quad ignition experiments. Work on optimizing the present design and refining the numerical simulations is currently pursued.
Directory of Open Access Journals (Sweden)
Garuma Abdisa Denu
2017-01-01
Full Text Available We report the effect of geometrical shape of diamond nanowire on its mechanical properties. Finite element modeling using COMSOL Multiphysics software is used to simulate various diamond nanowire with circular, square, rectangular, hexagonal and triangular cross-sections. A bending test under concentrated load applied at one of the free ends is simulated using FEM. The force response of the nanowire under different loading is studied for the various cross-sections. The dimensions of each cross-section is chosen so that material properties such as Young’s modulus can be kept constant for comparison in all the cross-sections. It is found out that the bending capability of a triangular nanowire is higher compared to other cross-sections due to its lowest second moment. Circular and hexagonal cross-section show highest stiffness. The study of mechanical property of diamond nanowires is useful for optimal nanomechanical designs where the effect of cross-section has to be taken into account.
Supply chain configuration concepts, solutions, and applications
Chandra, Charu
2016-01-01
This book discusses the models and tools available for solving configuration problems, emphasizes the value of model integration to obtain comprehensive and robust configuration decisions, proposes solutions for supply chain configuration in the presence of stochastic and dynamic factors, and illustrates application of the techniques discussed in applied studies. It is divided into four parts, which are devoted to defining the supply chain configuration problem and identifying key issues, describing solutions to various problems identified, proposing technologies for enabling supply chain confirmations, and discussing applied supply chain configuration problems. Its distinguishing features are: an explicit focus on the configuration problem an in-depth coverage of configuration models an emphasis on model integration and application of information modeling techniques in decision-making New to this edition is Part II: Technologies, which introduces readers to various technologies being utilized for supply chai...
Directory of Open Access Journals (Sweden)
Ilham Rizkianto
2013-07-01
Full Text Available Previous studies have provided that when learning shapes for the first time, young children tend to use the prototype as the reference point for comparisons, but often fail when doing so since they do not yet think about the defining attributes or the geometric properties of the shapes. Most of the time, elementary students learn geometric properties of shapes only as empty verbal statements to be memorized, without any chance to experience the contepts meaningfully. In the light of it, a sequence of instructional activities along with computer manipulative was designed to support Indonesian third graders in constructing geometric properties of square, rectangle, and triangle. The aim of the present study is to develop a loval instructional theory to support third graders in constructing geometric properties of rectangle, square, and triangle. Thirty seven students of one third grade classes in SD Pupuk Sriwijaya Palembang, along with their class teacher, were involved in the study. Our findings suggest that the combination of computer and non-computer activities suppots third graders in constructing geometric properties of square, rectangle, and triangle in that it provides opportunities to the students to experience and to develop the concepts meaningfully while using their real experiences as the bases to attain a higher geometric thinking level.Key concepts: Geometric properties, rectangle, square, triangle, design research, realistic mathematics education DOI: http://dx.doi.org/10.22342/jme.4.2.414.160-171
Geometry and topology of geometric limits I
Ohshika, Ken'ichi
2010-01-01
In this paper, we are concerned with hyperbolic 3-manifolds $\\hyperbolic^3/G$ such that $G$ are geometric limits of Kleinian surface groups isomorphic to $\\pi_1(S)$ for a finite-type hyperbolic surface $S$. In the first of the three main theorems, we shall show that such a hyperbolic 3-manifold is uniformly bi-Lipschitz homeomorphic to a model manifold which has a structure called brick decomposition and is embedded in $S \\times (0,1)$. Conversely, any such manifold admitting a brick decomposition with reasonable conditions is bi-Lipschitz homeomorphic to a hyperbolic manifold corresponding to some geometric limit of quasi-Fuchsian groups. Finally, it will be shown that we can define end invariants for hyperbolic 3-manifolds appearing as geometric limits of Kleinian surface groups, and that the homeomorphism type and the end invariants determine the isometric type of a manifold, which is analogous to the ending lamination theorem for the case of finitely generated Kleinian groups.
Chien, Sarina Hui-Lin
2011-05-20
A non-specific "top-heavy" configuration bias has been proposed to explain neonatal face preference (F. Simion, E. Valenza, V. Macchi Cassia, C. Turati, & C. Umiltà, 2002). Using an eye tracker (Tobii T60), we investigated whether the top-heavy bias is still present in 3- to 5.5-month-old infants and in adults as a comparison group. Each infant and adult viewed three classes of stimuli: simple geometric patterns, face-like figures, and photographs of faces. Using area of interest analyses on fixation duration, we computed a top-heavy bias index (a number between -1 and 1) for each individual. Our results showed that the indices for the geometric and face-like patterns were about zero in infants, indicating no consistent bias for the "top-heavy" configuration. In adults, the indices for the geometric and face-like patterns were also close to zero except for the T-shaped figure and the ones that had higher rating on facedness. Moreover, the indices for photographs of faces were positive in both infants and adults, indicating significant preferences for upright natural faces over inverted ones. Taken together, we found no evidence for the top-heavy configuration bias in both infants and adults. The absence of top-heavy bias plus a clear preference for photographed upright faces in infants seem to suggest an early cognitive specialization process toward face representation.
Murugan, Karmani; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Pillay, Viness
2017-09-01
This study aimed to highlight a statistic design to precisely engineer homogenous geometric copper nanoparticles (CuNPs) for enhanced intracellular drug delivery as a function of geometrical structure. CuNPs with a dual functionality comprising geometric attributes for enhanced cell uptake and exerting cytotoxic activity on proliferating cells were synthesized as a novel drug delivery system. This paper investigated the defined concentrations of two key surfactants used in the reaction to mutually control and manipulate nano-shape and optimisation of the geometric nanosystems. A statistical experimental design comprising a full factorial model served as a refining factor to achieve homogenous geometric nanoparticles using a one-pot method for the systematic optimisation of the geometric CuNPs. Shapes of the nanoparticles were investigated to determine the result of the surfactant variation as the aim of the study and zeta potential was studied to ensure the stability of the system and establish a nanosystem of low aggregation potential. After optimisation of the nano-shapes, extensive cellular internalisation studies were conducted to elucidate the effect of geometric CuNPs on uptake rates, in addition to the vital toxicity assays to further understand the cellular effect of geometric CuNPs as a drug delivery system. In addition to geometry; volume, surface area, orientation to the cell membrane and colloidal stability is also addressed. The outcomes of the study demonstrated the success of homogenous geometric NP formation, in addition to a stable surface charge. The findings of the study can be utilized for the development of a drug delivery system for promoted cellular internalisation and effective drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.
Reuther, James; Jameson, Antony; Alonso, Juan Jose; Rimlinger, Mark J.; Saunders, David
1997-01-01
An aerodynamic shape optimization method that treats the design of complex aircraft configurations subject to high fidelity computational fluid dynamics (CFD), geometric constraints and multiple design points is described. The design process will be greatly accelerated through the use of both control theory and distributed memory computer architectures. Control theory is employed to derive the adjoint differential equations whose solution allows for the evaluation of design gradient information at a fraction of the computational cost required by previous design methods. The resulting problem is implemented on parallel distributed memory architectures using a domain decomposition approach, an optimized communication schedule, and the MPI (Message Passing Interface) standard for portability and efficiency. The final result achieves very rapid aerodynamic design based on a higher order CFD method. In order to facilitate the integration of these high fidelity CFD approaches into future multi-disciplinary optimization (NW) applications, new methods must be developed which are capable of simultaneously addressing complex geometries, multiple objective functions, and geometric design constraints. In our earlier studies, we coupled the adjoint based design formulations with unconstrained optimization algorithms and showed that the approach was effective for the aerodynamic design of airfoils, wings, wing-bodies, and complex aircraft configurations. In many of the results presented in these earlier works, geometric constraints were satisfied either by a projection into feasible space or by posing the design space parameterization such that it automatically satisfied constraints. Furthermore, with the exception of reference 9 where the second author initially explored the use of multipoint design in conjunction with adjoint formulations, our earlier works have focused on single point design efforts. Here we demonstrate that the same methodology may be extended to treat
Aerodynamic Shape Optimization of Complex Aircraft Configurations via an Adjoint Formulation
Reuther, James; Jameson, Antony; Farmer, James; Martinelli, Luigi; Saunders, David
1996-01-01
This work describes the implementation of optimization techniques based on control theory for complex aircraft configurations. Here control theory is employed to derive the adjoint differential equations, the solution of which allows for a drastic reduction in computational costs over previous design methods (13, 12, 43, 38). In our earlier studies (19, 20, 22, 23, 39, 25, 40, 41, 42) it was shown that this method could be used to devise effective optimization procedures for airfoils, wings and wing-bodies subject to either analytic or arbitrary meshes. Design formulations for both potential flows and flows governed by the Euler equations have been demonstrated, showing that such methods can be devised for various governing equations (39, 25). In our most recent works (40, 42) the method was extended to treat wing-body configurations with a large number of mesh points, verifying that significant computational savings can be gained for practical design problems. In this paper the method is extended for the Euler equations to treat complete aircraft configurations via a new multiblock implementation. New elements include a multiblock-multigrid flow solver, a multiblock-multigrid adjoint solver, and a multiblock mesh perturbation scheme. Two design examples are presented in which the new method is used for the wing redesign of a transonic business jet.
Perceptual separability of featural and configural information in congenital prosopagnosia.
Kimchi, Ruth; Behrmann, Marlene; Avidan, Galia; Amishav, Rama
2012-01-01
The deficit in face recognition in individuals with prosopagnosia has often been attributed to an underlying impairment in holistic processing. Exactly what constitutes holistic processing has remained controversial, however. Here, we compare how configural information and featural information interact during face processing in a group of individuals with congenital prosopagnosia (CP) and matched controls. We adopted Amishav and Kimchi's version of Garner's speeded classification task, in which observers classify upright faces based on configural (intereyes and nose-mouth spacing) or featural (shape of eyes, nose, and mouth) information while the other dimension remains constant or varied randomly. We replicated the finding that normal observers evince symmetric Garner interference--failure to selectively attend to features without being influenced by irrelevant variation in configuration, and vice versa--indicating that featural and configural information are integral in normal face processing. In contrast, the CPs showed no Garner interference: They were able to attend to configural information without interference from irrelevant variation in featural information, and they were able to attend to featural information without interference from irrelevant variation in configural information. The absence of Garner interference in CP provides strong evidence that featural information and configural information are perceptually separable in CP's face processing. These findings indicate that CPs do not perceive faces holistically; rather, they process featural and configural information independently.
Fitting and Analyzing Randomly Censored Geometric Extreme Exponential Distribution
Directory of Open Access Journals (Sweden)
Muhammad Yameen Danish
2016-06-01
Full Text Available The paper presents the Bayesian analysis of two-parameter geometric extreme exponential distribution with randomly censored data. The continuous conjugate prior of the scale and shape parameters of the model does not exist while computing the Bayes estimates, it is assumed that the scale and shape parameters have independent gamma priors. It is seen that the closed-form expressions for the Bayes estimators are not possible; we suggest the Lindley’s approximation to obtain the Bayes estimates. However, the Bayesian credible intervals cannot be constructed while using this method, we propose Gibbs sampling to obtain the Bayes estimates and also to construct the Bayesian credible intervals. Monte Carlo simulation study is carried out to observe the behavior of the Bayes estimators and also to compare with the maximum likelihood estimators. One real data analysis is performed for illustration.
Hyperbolic functions with configuration theorems and equivalent and equidecomposable figures
Shervatov, V G; Skornyakov, L A; Boltyanskii, V G
2007-01-01
This single-volume compilation of three books centers on Hyperbolic Functions, an introduction to the relationship between the hyperbolic sine, cosine, and tangent, and the geometric properties of the hyperbola. The development of the hyperbolic functions, in addition to those of the trigonometric (circular) functions, appears in parallel columns for comparison. A concluding chapter introduces natural logarithms and presents analytic expressions for the hyperbolic functions.The second book, Configuration Theorems, requires only the most elementary background in plane and solid geometry. It dis
Jet Engine Nozzle Exit Configurations and Associated Systems and Methods
Mengle, Vinod G. (Inventor)
2013-01-01
Nozzle exit configurations and associated systems and methods are disclosed. An aircraft system in accordance with one embodiment includes a jet engine exhaust nozzle having an internal flow surface and an exit aperture, with the exit aperture having a perimeter that includes multiple projections extending in an aft direction. Aft portions of individual neighboring projections are spaced apart from each other by a gap, and a geometric feature of the multiple can change in a monotonic manner along at least a portion of the perimeter.
Geometric Approaches to Quadratic Equations from Other Times and Places.
Allaire, Patricia R.; Bradley, Robert E.
2001-01-01
Focuses on geometric solutions of quadratic problems. Presents a collection of geometric techniques from ancient Babylonia, classical Greece, medieval Arabia, and early modern Europe to enhance the quadratic equation portion of an algebra course. (KHR)
Phasukkit, Pattarapong; Tungjitkusolmun, Supan; Sangworasil, Manas
2009-11-01
This study presents analyses of triple-antenna configurations and designs for microwave (MW) hepatic ablation using 3-D finite-element (FE) analyses verified by in vitro experiments. Treatment of hepatic cancer often requires removal or destruction of large volume lesions. Using multiple antennas offers a potential solution for creating ablation zones with larger dimensions, as well as varied geometrical shapes. We performed both 3-D FE analyses and in vitro experiments using three identical open-tip MW antennas simultaneously, placing them in three types of configurations-"linear array," "triangular," and "T-shaped" arrangements. We compared coagulation volumes created, as well as temperature distribution characteristics, from the three-antenna arrangements after power delivery of 50 W for 60 s. We also performed additional tests using nonidentical antennas (open tip, slot, and slot with insulating jacket) for the three configurations. The results illustrate that arranging antennas in the "T-shaped" pattern destroyed more unwanted tissues than those found when using "linear array" and "triangular" arrangements, with maximum coagulation width and depth of 46 and 81 mm, respectively, and coagulation volume of 30.7 cm(3) . In addition, using nonidentical triple antennas caused variations in coagulation zone characteristics, and thus, the technique could be applied to treatment situations where nonsymmetric coagulation zones are required.
Haptic spatial configuration learning in deaf and hearing individuals
Dijk, van R; Kappers, A.M.L.; Postma, A.
2013-01-01
The present study investigated haptic spatial configuration learning in deaf individuals, hearing sign language interpreters and hearing controls. In three trials, participants had to match ten shapes haptically to the cut-outs in a board as fast as possible. Deaf and hearing sign language users out
Finite Geometric Structures and their Applications
Barlotti, A
2011-01-01
This title covers such topics as: R.C. Bose - Graphs and designs; R.H. Bruck - Construction problems in finite projective spaces; R.H.F. Denniston - Packings of PG(3,q); J. Doyen - Recent results on Steiner triple systems; H. Luneburg - Gruppen und endliche projektive Ebenen; J.A. Thas - 4-gonal configurations; and, H.P. Young - Affine triple systems.
Geometric measure theory and real analysis
2014-01-01
In 2013, a school on Geometric Measure Theory and Real Analysis, organized by G. Alberti, C. De Lellis and myself, took place at the Centro De Giorgi in Pisa, with lectures by V. Bogachev, R. Monti, E. Spadaro and D. Vittone. The book collects the notes of the courses. The courses provide a deep and up to date insight on challenging mathematical problems and their recent developments: infinite-dimensional analysis, minimal surfaces and isoperimetric problems in the Heisenberg group, regularity of sub-Riemannian geodesics and the regularity theory of minimal currents in any dimension and codimension.
Mechanics of tunable helices and geometric frustration in biomimetic seashells
Guo, Qiaohang; Chen, Zi; Li, Wei; Dai, Pinqiang; Ren, Kun; Lin, Junjie; Taber, Larry A.; Chen, Wenzhe
2014-03-01
Helical structures are ubiquitous in nature and engineering, ranging from DNA molecules to plant tendrils, from sea snail shells to nanoribbons. While the helical shapes in natural and engineered systems often exhibit nearly uniform radius and pitch, helical shell structures with changing radius and pitch, such as seashells and some plant tendrils, add to the variety of this family of aesthetic beauty. Here we develop a comprehensive theoretical framework for tunable helical morphologies, and report the first biomimetic seashell-like structure resulting from mechanics of geometric frustration. In previous studies, the total potential energy is everywhere minimized when the system achieves equilibrium. In this work, however, the local energy minimization cannot be realized because of the geometric incompatibility, and hence the whole system deforms into a shape with a global energy minimum whereby the energy in each segment may not necessarily be locally optimized. This novel approach can be applied to develop materials and devices of tunable geometries with a range of applications in nano/biotechnology.
A hybrid configuration interaction treatment based on seniority number and excitation schemes
Energy Technology Data Exchange (ETDEWEB)
Alcoba, Diego R.; Capuzzi, Pablo [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Física de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Torre, Alicia; Lain, Luis, E-mail: qfplapel@lg.ehu.es [Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apdo. 644 E-48080 Bilbao (Spain); Oña, Ofelia B. [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Universidad Nacional de La Plata, CCT La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Diag. 113 y 64 (S/N), Sucursal 4, CC 16, 1900 La Plata (Argentina); Van Raemdonck, Mario; Bultinck, Patrick [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 (S3), 9000 Gent (Belgium); Van Neck, Dimitri [Center for Molecular Modelling, Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium)
2014-12-28
We present a configuration interaction method in which the Hamiltonian of an N-electron system is projected on Slater determinants selected according to the seniority-number criterion along with the traditional excitation-based procedure. This proposed method is especially useful to describe systems which exhibit dynamic (weak) correlation at determined geometric arrangements (where the excitation-based procedure is more suitable) but show static (strong) correlation at other arrangements (where the seniority-number technique is preferred). The hybrid method amends the shortcomings of both individual determinant selection procedures, yielding correct shapes of potential energy curves with results closer to those provided by the full configuration interaction method.
Geometrical and Monte Carlo projectors in 3D PET reconstruction
Aguiar, Pablo; Rafecas López, Magdalena; Ortuno, Juan Enrique; Kontaxakis, George; Santos, Andrés; Pavía, Javier; Ros, Domènec
2010-01-01
Purpose: In the present work, the authors compare geometrical and Monte Carlo projectors in detail. The geometrical projectors considered were the conventional geometrical Siddon ray-tracer (S-RT) and the orthogonal distance-based ray-tracer (OD-RT), based on computing the orthogonal distance from the center of image voxel to the line-of-response. A comparison of these geometrical projectors was performed using different point spread function (PSF) models. The Monte Carlo-based method under c...
Discretized configurations and partial partitions
Abrams, Aaron; Hower, Valerie
2010-01-01
We show that the discretized configuration space of $k$ points in the $n$-simplex is homotopy equivalent to a wedge of spheres of dimension $n-k+1$. This space is homeomorphic to the order complex of the poset of ordered partial partitions of $\\{1,\\...,n+1\\}$ with exactly $k$ parts. We also compute the Euler characteristic in two different ways, thereby obtaining a topological proof of a combinatorial recurrence satisfied by the Stirling numbers of the second kind.
Minimal representations, geometric quantization, and unitarity.
Brylinski, R; Kostant, B
1994-06-21
In the framework of geometric quantization we explicitly construct, in a uniform fashion, a unitary minimal representation pio of every simply-connected real Lie group Go such that the maximal compact subgroup of Go has finite center and Go admits some minimal representation. We obtain algebraic and analytic results about pio. We give several results on the algebraic and symplectic geometry of the minimal nilpotent orbits and then "quantize" these results to obtain the corresponding representations. We assume (Lie Go)C is simple.
An Intuitive Approach to Geometric Continuity for Parametric Curves and Surfaces (Extended Abstract)
Derose, T. D.; Barsky, B. A.
1985-01-01
The notion of geometric continuity is extended to an arbitrary order for curves and surfaces, and an intuitive development of constraints equations is presented that are necessary for it. The constraints result from a direct application of the univariate chain rule for curves, and the bivariate chain rule for surfaces. The constraints provide for the introduction of quantities known as shape parameters. The approach taken is important for several reasons: First, it generalizes geometric continuity to arbitrary order for both curves and surfaces. Second, it shows the fundamental connection between geometric continuity of curves and geometric continuity of surfaces. Third, due to the chain rule derivation, constraints of any order can be determined more easily than derivations based exclusively on geometric measures.
Geometric and numerical foundations of movements
Mansard, Nicolas; Lasserre, Jean-Bernard
2017-01-01
This book aims at gathering roboticists, control theorists, neuroscientists, and mathematicians, in order to promote a multidisciplinary research on movement analysis. It follows the workshop “ Geometric and Numerical Foundations of Movements ” held at LAAS-CNRS in Toulouse in November 2015[1]. Its objective is to lay the foundations for a mutual understanding that is essential for synergetic development in motion research. In particular, the book promotes applications to robotics --and control in general-- of new optimization techniques based on recent results from real algebraic geometry.
Borie, B.; Kehlberger, A.; Wahrhusen, J.; Grimm, H.; Kläui, M.
2017-08-01
We study the key domain-wall properties in segmented nanowire loop-based structures used in domain-wall-based sensors. The two reasons for device failure, namely, distribution of the domain-wall propagation field (depinning) and the nucleation field are determined with magneto-optical Kerr effect and giant-magnetoresistance (GMR) measurements for thousands of elements to obtain significant statistics. Single layers of Ni81 Fe19 , a complete GMR stack with Co90 Fe10 /Ni81Fe19 as a free layer, and a single layer of Co90 Fe10 are deposited and industrially patterned to determine the influence of the shape anisotropy, the magnetocrystalline anisotropy, and the fabrication processes. We show that the propagation field is influenced only slightly by the geometry but significantly by material parameters. Simulations for a realistic wire shape yield a curling-mode type of magnetization configuration close to the nucleation field. Nonetheless, we find that the domain-wall nucleation fields can be described by a typical Stoner-Wohlfarth model related to the measured geometrical parameters of the wires and fitted by considering the process parameters. The GMR effect is subsequently measured in a substantial number of devices (3000) in order to accurately gauge the variation between devices. This measurement scheme reveals a corrected upper limit to the nucleation fields of the sensors that can be exploited for fast characterization of the working elements.
Identifying and Fostering Higher Levels of Geometric Thinking
Škrbec, Maja; Cadež, Tatjana Hodnik
2015-01-01
Pierre M. Van Hiele created five levels of geometric thinking. We decided to identify the level of geometric thinking in the students in Slovenia, aged 9 to 11 years. The majority of students (60.7%) are at the transition between the zero (visual) level and the first (descriptive) level of geometric thinking. Nearly a third (31.7%) of students is…
METAMORPHIC MECHANISMS AND THEIR CONFIGURATION MODELS
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The concept of metamorphic mechanisms is presented, configuration models and configuration transformations relating to a set of new matrix operations are discussed and proposed. The configuration of a m etamorphic mechanism reflects the connectivity change in the mechanism during motions which r esults in mobility change and presents the characteristics of the mechanism which is discussed in various applications particularly in decorative artifacts. The characteristics is further investigated with mobility analysis.
International Space Station Configuration Analysis and Integration
Anchondo, Rebekah
2016-01-01
Ambitious engineering projects, such as NASA's International Space Station (ISS), require dependable modeling, analysis, visualization, and robotics to ensure that complex mission strategies are carried out cost effectively, sustainably, and safely. Learn how Booz Allen Hamilton's Modeling, Analysis, Visualization, and Robotics Integration Center (MAVRIC) team performs engineering analysis of the ISS Configuration based primarily on the use of 3D CAD models. To support mission planning and execution, the team tracks the configuration of ISS and maintains configuration requirements to ensure operational goals are met. The MAVRIC team performs multi-disciplinary integration and trade studies to ensure future configurations meet stakeholder needs.
Algebraic renormalization and Feynman integrals in configuration spaces
Ceyhan, Ozgur
2013-01-01
This paper continues our previous study of Feynman integrals in configuration spaces and their algebro-geometric and motivic aspects. We consider here both massless and massive Feynman amplitudes, from the point of view of potential theory. We consider a variant of the wonderful compactification of configuration spaces that works simultaneously for all graphs with a given number of vertices and that also accounts for the external structure of Feynman graph. As in our previous work, we consider two version of the Feynman amplitude in configuration space, which we refer to as the real and complex versions. In the real version, we show that we can extend to the massive case a method of evaluating Feynman integrals, based on expansion in Gegenbauer polynomials, that we investigated previously in the massless case. In the complex setting, we show that we can use algebro-geometric methods to renormalize the Feynman amplitudes, so that the renormalized values of the Feynman integrals are given by periods of a mixed ...
Energy Technology Data Exchange (ETDEWEB)
Mahato, B. K.; Choudhury, S.; Mandal, R.; Barman, S.; Barman, A., E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Otani, Y. [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)
2015-06-07
We present broadband ferromagnetic resonance measurements of tunable spin wave anisotropy in arrays of nanodots with different dot shapes. Magnetization dynamics of the circular dot array shows two modes, while square, diamond, and triangular dot arrays show three, three, and four modes, respectively. Various distinct rotational symmetries in the configurational anisotropy of the nanodot arrays are observed with the variation of dot shape. The observed spin wave modes are reproduced by micromagnetic simulations and the calculated mode profiles show different collective modes determined by internal and stray magnetic fields. Effects of dot shapes are observed in combination with the effects of lattice symmetry and the shape of the boundary of the array. The collective behaviour is observed to be weakest in the diamond shaped dots and strongest in circular shaped dots. This is further confirmed by the stray field calculation. The large variation of spin wave mode frequencies and their configurational anisotropies with dot shapes are important for selection of suitable basis structures for future magnonic crystals.
More On Gauge Theory And Geometric Langlands
Witten, Edward
2015-01-01
The geometric Langlands correspondence was described some years ago in terms of $S$-duality of $\\N=4$ super Yang-Mills theory. Some additional matters relevant to this story are described here. The main goal is to explain directly why an $A$-brane of a certain simple kind can be an eigenbrane for the action of 't Hooft operators. To set the stage, we review some facts about Higgs bundles and the Hitchin fibration. We consider only the simplest examples, in which many technical questions can be avoided.
Geometric massive higher spins and current exchanges
Francia, Dario
2008-01-01
Generalised Fierz-Pauli mass terms allow to describe massive higher-spin fields on flat background by means of simple quadratic deformations of the corresponding geometric, massless Lagrangians. In this framework there is no need for auxiliary fields. We briefly review the construction in the bosonic case and study the interaction of these massive fields with external sources, computing the corresponding propagators. In the same fashion as for the massive graviton, but differently from theories where auxiliary fields are present, the structure of the current exchange is completely determined by the form of the mass term itself.
Curves and surfaces for computer-aided geometric design a practical guide
Farin, Gerald
1992-01-01
A leading expert in CAGD, Gerald Farin covers the representation, manipulation, and evaluation of geometric shapes in this the Third Edition of Curves and Surfaces for Computer Aided Geometric Design. The book offers an introduction to the field that emphasizes Bernstein-Bezier methods and presents subjects in an informal, readable style, making this an ideal text for an introductory course at the advanced undergraduate or graduate level.The Third Edition includes a new chapter on Topology, offers new exercises and sections within most chapters, combines the material on Geometric Continuity i
Geometric analysis of root canals prepared by four rotary NiTi shaping systems.
Hashem, Ahmed Abdel Rahman; Ghoneim, Angie Galal; Lutfy, Reem Ahmed; Foda, Manar Yehia; Omar, Gihan Abdel Fatah
2012-07-01
A great number of nickel-titanium (NiTi) rotary systems with noncutting tips, different cross-sections, superior resistance to torsional fracture, varying tapers, and manufacturing method have been introduced to the market. The purpose of this study was to evaluate and compare the effect of 4 rotary NiTi preparation systems, Revo-S (RS; Micro-Mega, Besancon Cedex, France), Twisted file (TF; SybronEndo, Amersfoort, The Netherlands), ProFile GT Series X (GTX; Dentsply, Tulsa Dental Specialties, Tulsa, OK), and ProTaper (PT; Dentsply Maillefer, Ballaigues, Switzerland), on volumetric changes and transportation of curved root canals. Forty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 25° to 40° were divided according to the instrument used in canal preparation into 4 groups of 10 samples each: group RS, group TF, group GTX, and group PT. Canals were scanned using an i-CAT CBCT scanner (Imaging Science International, Hatfield, PA) before and after preparation to evaluate the volumetric changes. Root canal transportation and centering ratio were evaluated at 1.3, 2.6, 5.2, and 7.8 mm from the apex. The significance level was set at P ≤ .05. The PT system removed a significantly higher amount of dentin than the other systems (P = .025). At the 1.3-mm level, there was no significant difference in canal transportation and centering ratio among the groups. However, at the other levels, TF maintained the original canal curvature recording significantly the least degree of canal transportation as well as the highest mean centering ratio. The TF system showed superior shaping ability in curved canals. Revo-S and GTX were better than ProTaper regarding both canal transportation and centering ability. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Geometric Primitive Extraction by the Combination of Tabu Search and Subpixel Accuracy
Institute of Scientific and Technical Information of China (English)
JIANG Tianzi
1999-01-01
In this paper, a novel method for extracting the geometric primitives from geometric data is proposed. Specifically, tabu search is combined with subpixel accuracy to improve detection accuracy and convergent speed. On the one hand, this new shape detection method not only has TS's ability to find the global optimum, but alsokeeps all advantages of tabu search. On the other hand, it has subpixel accuracy ability to match the local optimum.
GEOMETRIC AND RADIOMETRIC EVALUATION OF RASAT IMAGES
Directory of Open Access Journals (Sweden)
A. Cam
2016-06-01
Full Text Available RASAT, the second remote sensing satellite of Turkey, was designed and assembled, and also is being operated by TÜBİTAK Uzay (Space Technologies Research Institute (Ankara. RASAT images in various levels are available free-of-charge via Gezgin portal for Turkish citizens. In this paper, the images in panchromatic (7.5 m GSD and RGB (15 m GSD bands in various levels were investigated with respect to its geometric and radiometric characteristics. The first geometric analysis is the estimation of the effective GSD as less than 1 pixel for radiometrically processed level (L1R of both panchromatic and RGB images. Secondly, 2D georeferencing accuracy is estimated by various non-physical transformation models (similarity, 2D affine, polynomial, affine projection, projective, DLT and GCP based RFM reaching sub-pixel accuracy using minimum 39 and maximum 52 GCPs. The radiometric characteristics are also investigated for 8 bits, estimating SNR between 21.8-42.2, and noise 0.0-3.5 for panchromatic and MS images for L1R when the sea is masked to obtain the results for land areas. The analysis show that RASAT images satisfies requirements for various applications. The research is carried out in Zonguldak test site which is mountainous and partly covered by dense forest and urban areas.
Geometrical symmetries of nuclear systems: D(3h) and T(d) symmetries in light nuclei
Bijker, Roelof
2016-01-01
The role of discrete (or point-group) symmetries in alpha-cluster nuclei is discussed in the framework of the algebraic cluster model which describes the relative motion of the alpha-particles. Particular attention is paid to the discrete symmetry of the geometric arrangement of the alpha-particles, and the consequences for the structure of the corresponding rotational bands. The method is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in a simple way as a consequence of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle with D(3h) symmetry for 12C, and a tetrahedron with T(d) symmetry for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
Geometric design of crab-like climbing and walking robots
Institute of Scientific and Technical Information of China (English)
LIU An-min; David Howard
2004-01-01
This paper considers the geometric design of crab-like walkers and climbers, without decoupling leg design from overall machine design. Crab-like machines represent an important sub-class of multi-legged robots, being particularly well suited to crossing difficult terrains. Firstly, the kinematic configurations and constraints are described, which determine the machine's kinematic characteristics. The influence of the design parameters on the kinematic workspace is discussed. Finally,a two stage design methodology is presented, comprising kinematic design and design optimisation, the latter being based on the use of design maps rather than numerical optimisation. The performance measures considered during design optimisation include kinematic, static and quasi-static measures.
Geometrical Lorentz Violation and Quantum Mechanical Physics
Mignani, R; Cardone, F
2013-01-01
On the basis of the results of some experiments dealing with the violation of Local Lorentz Invariance (LLI) and on the formalism of the Deformed Special Relativity (DSR), we examine the connections between the local geometrical structure of space-time and the foundation of Quantum Mechanics. We show that Quantum Mechanics, beside being an axiomatic theory, can be considered also a deductive physical theory, deducted from the primary physical principle of Relativistic Correlation. This principle is synonym of LLI and of a rigid and at minkowskian space-time. The results of the experiments mentioned above show the breakdown of LLI and hence the violation of the principle of Relativistic Correlation. The formalism of DSR allows to highlight the deep meaning of LLI breakdown in terms of the geometrical structure of local space-time which, far from being rigid and at, is deformed by the energy of the physical phenomena that take place and in this sense it has an active part in the dynamics of the whole physical p...
Role of geometrical shape in like-charge attraction of DNA.
Kuron, Michael; Arnold, Axel
2015-03-01
While the phenomenon of like-charge attraction of DNA is clearly observed experimentally and in simulations, mean-field theories fail to predict it. Kornyshev et al. argued that like-charge attraction is due to DNA's helical geometry and hydration forces. Strong-coupling (SC) theory shows that attraction of like-charged rods is possible through ion correlations alone at large coupling parameters, usually by multivalent counterions. However for SC theory to be applicable, counterion-counterion correlations perpendicular to the DNA strands need to be sufficiently small, which is not a priori the case for DNA even with trivalent counterions. We study a system containing infinitely long DNA strands and trivalent counterions by computer simulations employing varying degrees of coarse-graining. Our results show that there is always attraction between the strands, but its magnitude is indeed highly dependent on the specific shape of the strand. While discreteness of the charge distribution has little influence on the attractive forces, the role of the helical charge distribution is considerable: charged rods maintain a finite distance in equilibrium, while helices collapse to close contact with a phase shift of π, in full agreement with SC predictions. The SC limit is applicable because counterions strongly bind to the charged sites of the helices, so that helix-counterion interactions dominate over counterion-counterion interactions. Thus DNA's helical geometry is not crucial for like-charge DNA attraction, but strongly enhances it, and electrostatic interactions in the strong-coupling limit are sufficient to explain this attraction.
Geometric symmetries in light nuclei
Bijker, Roelof
2016-01-01
The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
On supersymmetric geometric flows and R2 inflation from scale invariant supergravity
Rajpoot, Subhash; Vacaru, Sergiu I.
2017-09-01
Models of geometric flows pertaining to R2 scale invariant (super) gravity theories coupled to conformally invariant matter fields are investigated. Related to this work are supersymmetric scalar manifolds that are isomorphic to the Kählerian spaces Mn = SU(1 , 1 + k) / U(1) × SU(1 + k) as generalizations of the non-supersymmetric analogs with SO(1 , 1 + k) / SO(1 + k) manifolds. For curved superspaces with geometric evolution of physical objects, a complete supersymmetric theory has to be elaborated on nonholonomic (super) manifolds and bundles determined by non-integrable superdistributions with additional constraints on (super) field dynamics and geometric evolution equations. We also consider generalizations of Perelman's functionals using such nonholonomic variables which result in the decoupling of geometric flow equations and Ricci soliton equations with supergravity modifications of the R2 gravity theory. As such, it is possible to construct exact non-homogeneous and locally anisotropic cosmological solutions for various types of (super) gravity theories modeled as modified Ricci soliton configurations. Such solutions are defined by employing the general ansatz encompassing coefficients of generic off-diagonal metrics and generalized connections that depend generically on all spacetime coordinates. We consider nonholonomic constraints resulting in diagonal homogeneous configurations encoding contributions from possible nonlinear parametric geometric evolution scenarios, off-diagonal interactions and anisotropic polarization/modification of physical constants. In particular, we analyze small parametric deformations when the underlying scale symmetry is preserved and the nontrivial anisotropic vacuum corresponds to generalized de Sitter spaces. Such configurations may mimic quantum effects whenever transitions to flat space are possible. Our approach allows us to generate solutions with scale violating terms induced by geometric flows, off
Ning, Xiaojuan; Wang, Yinghui; Zhang, Xiaopeng
2013-02-01
Shape analysis of a three-dimensional (3-D) scene is an important issue and could be widely used for various applications: city planning, robot navigation, virtual tourism, etc. We introduce an approach for understanding the primitive shape of the scene to reveal the semantic scene shape structure and represent the scene using shape elements. The scene objects are labeled and recognized using the geometric and semantic features for each cluster, which is based on the knowledge of scene. Furthermore, the object in scene with a different primitive shape could also be classified and fitted using the Gaussian map of the segmented scene. We demonstrate the presented approach on several complex scenes from laser scanning. According to the experimental result, the proposed method can accurately represent the geometric structure of the 3-D scene.
Structural applications of metal foams considering material and geometrical uncertainty
Moradi, Mohammadreza
Metal foam is a relatively new and potentially revolutionary material that allows for components to be replaced with elements capable of large energy dissipation, or components to be stiffened with elements which will generate significant supplementary energy dissipation when buckling occurs. Metal foams provide a means to explore reconfiguring steel structures to mitigate cross-section buckling in many cases and dramatically increase energy dissipation in all cases. The microstructure of metal foams consists of solid and void phases. These voids have random shape and size. Therefore, randomness ,which is introduced into metal foams during the manufacturing processes, creating more uncertainty in the behavior of metal foams compared to solid steel. Therefore, studying uncertainty in the performance metrics of structures which have metal foams is more crucial than for conventional structures. Therefore, in this study, structural application of metal foams considering material and geometrical uncertainty is presented. This study applies the Sobol' decomposition of a function of many random variables to different problem in structural mechanics. First, the Sobol' decomposition itself is reviewed and extended to cover the case in which the input random variables have Gaussian distribution. Then two examples are given for a polynomial function of 3 random variables and the collapse load of a two story frame. In the structural example, the Sobol' decomposition is used to decompose the variance of the response, the collapse load, into contributions from the individual input variables. This decomposition reveals the relative importance of the individual member yield stresses in determining the collapse load of the frame. In applying the Sobol' decomposition to this structural problem the following issues are addressed: calculation of the components of the Sobol' decomposition by Monte Carlo simulation; the effect of input distribution on the Sobol' decomposition
Ang, Qian Yee; Zolkeflay, Muhammad Helmi; Low, Siew Chun
2016-04-01
In this study, sol-gel processing was proposed to prepare a creatinine (Cre)-imprinted molecularly imprinted polymer (MIP). The intermolecular interaction constituted by the cross-linkers, i.e., 2-acrylamido-2-methylpropane-sulfonic acid (AMPS) and aluminium ion (Al3+), was studied and compared in order to form a confined matrix that promises the effectiveness of molecular imprinting. In view of the shape recognition, the hydrogen bonded Cre-AMPS did not demonstrate good recognition of Cre, with Cre binding found only at 5.70 ± 0.15 mg g-1 of MIP. Whilst, MIP cross-linked using Al3+ was able to attain an excellent Cre adsorption capacity of 19.48 ± 0.64 mg g-1 of MIP via the stronger ionic interaction of Cre-Al3+. Based on the Scatchard analysis, a higher Cre concentration in testing solution required greater driving force to resolve the binding resistance of Cre molecules, so as to have a precise Cre binding with shape factor. The molecular recognition ability of Cre-MIP in present work was shape-specific for Cre as compared to its structural analogue, 2-pyrrolidinone (2-pyr), by an ideal selectivity coefficient of 6.57 ± 0.10. In overall, this study has come up with a practical approach on the preparation of MIP for the detection of renal dysfunction by point-of-care Cre testing.
On geometric Langlands theory and stacks
Poirier, Cécile Florence Christine
2008-01-01
R.Langlands conjectured the existence of a bridge between two parts of number theory. This correspondence, called 'Langlands conjecture' was proved by L. Lafforgue who obtained a Fields medal for his work. G. Laumon gave a geometric translation of a part of the theorem, called 'geometric Langlands c
Geometrical optics and the diffraction phenomenon
Energy Technology Data Exchange (ETDEWEB)
Timofeev, Aleksandr V [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2005-06-30
This note outlines the principles of the geometrical optics of inhomogeneous waves whose description necessitates the use of complex values of the wave vector. Generalizing geometrical optics to inhomogeneous waves permits including in its scope the analysis of the diffraction phenomenon. (methodological notes)
Marking up lattice QCD configurations and ensembles
Coddington, P; Maynard, C M; Pleiter, D; Yoshié, T
2007-01-01
QCDml is an XML-based markup language designed for sharing QCD configurations and ensembles world-wide via the International Lattice Data Grid (ILDG). Based on the latest release, we present key ingredients of the QCDml in order to provide some starting points for colleagues in this community to markup valuable configurations and submit them to the ILDG.
Geometry and crystallographic configuration of grain boundaries
Eichler, Jan; Weikusat, Ilka; Kipfstuhl, Sepp; Binder, Tobias
2015-04-01
Ice cores provide a unique opportunity to study fundamental mechanisms which control the internal flow of ice sheets. Different kinds of deformation processes acting on the micro-scale are responsible for the viscoplastic behavior on large scale. Careful interpretation of microstructural features such as grain size, shape, lattice orientation and the occurrence of subgrain boundaries can help us to follow these processes and to improve our understanding of ice rheology. Polarized light microscopy experienced a quick development in the last decade. A new generation of automatic fabric analyzers enables to measure c-axis orientations in µm-resolution. This high amount and quality of fabric data motivates to apply digital-image-processing routines (DIP) for the recognition and quantification of microstructural patterns. Here we present a study on grain boundaries based on the acquisition of more than 700 fabric images recorded along the NEEM ice core (Greenland). Geometrical characteristics of grain boundaries are studied as well as their cross-sectional orientations in relation to the c-axis orientations of the corresponding adjacent grains. We could follow the evolution from the initial N-type and P-type low-angle boundaries (Weikusat et al., 2011) to high angle boundaries during rotation recrystallization. In agreement with some previous studies we confirm that the established three-stage-recrystallization model may be an oversimplification. According to our results, rotation recrystallization as well as grain boundary migration are actually present in all depths with varying intensities at NEEM. I. Weikusat, A. Miyamoto, S. H. Faria, S. Kipfstuhl, N. Azuma, and T. Hondoh: Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction. J. Glaciol., 57(201):85-94, 2011. doi: 10013/epic.36402.
Geometric Properties of Grassmannian Frames for and
Directory of Open Access Journals (Sweden)
Benedetto John J
2006-01-01
Full Text Available Grassmannian frames are frames satisfying a min-max correlation criterion. We translate a geometrically intuitive approach for two- and three-dimensional Euclidean space ( and into a new analytic method which is used to classify many Grassmannian frames in this setting. The method and associated algorithm decrease the maximum frame correlation, and hence give rise to the construction of specific examples of Grassmannian frames. Many of the results are known by other techniques, and even more generally, so that this paper can be viewed as tutorial. However, our analytic method is presented with the goal of developing it to address unresovled problems in -dimensional Hilbert spaces which serve as a setting for spherical codes, erasure channel modeling, and other aspects of communications theory.
Thermodynamic and magnetocaloric properties of geometrically frustrated Ising nanoclusters
Energy Technology Data Exchange (ETDEWEB)
Žukovič, M., E-mail: milan.zukovic@upjs.sk
2015-01-15
Thermodynamic and magnetocaloric properties of geometrically frustrated Ising spin clusters of selected shapes and sizes are studied by exact enumeration. In the ground state the magnetization and the entropy show step-wise variations with an applied magnetic field. The number of steps, their widths and heights depend on the cluster shape and size. While the character of the magnetization plateau heights is always increasing, the entropy is not necessarily decreasing function of the field, as one would expect. For selected clusters showing some interesting ground-state properties, the calculations are extended to finite temperatures by exact enumeration of densities of states in the energy-magnetization space. In zero field the focus is laid on a peculiar behavior of some thermodynamic quantities, such as the entropy, the specific heat and the magnetic susceptibility. In finite fields various thermodynamic functions are studied in the temperature-field parameter plane and particular attention is paid to the cases showing an enhanced magnetocaloric effect. The exact results on the finite clusters are compared with the thermodynamic limit behavior obtained from Monte Carlo simulations. - Highlights: • We study frustrated spin clusters of various shapes and sizes on a triangular lattice. • Ground-state magnetizations and entropies in a field are exactly determined. • Peculiar behavior of some quantities is studied in zero field and finite temperatures. • Enhanced magnetocaloric effect is observed at relatively low temperatures and fields. • Thermodynamic limit behavior is estimated by Monte Carlo simulations.
Directory of Open Access Journals (Sweden)
A. García Rodríguez
2005-05-01
Full Text Available La presente publicación propone un método integral configurable y flexible para facilitar el ensayo de materialesconsumibles de soldadura por arco eléctrico en las condiciones tecnológicas para las que han sido diseñados estosmateriales, en relación a la calidad de la unión soldada. Se puede llegar a conclusiones definitivas sobre la calidad de lasoldadura usando un determinado material consumible mediante: la relación operacional de técnicas de inteligencia naturaly/o artificial, el uso de sistemas expertos, el trabajo con bases de datos, la simulación y la realización práctica del procesomientras se registran ciertos parámetros del arco eléctrico, digitalmente procesados estadísticamente y relacionados a losresultados de la caracterización de la unión soldada. El método permite registrar adecuadamente la información referente acada aspecto del proceso exigida en los procesos de certificación de la calidad de los consumibles, así como en lainvestigación dirigida a optimizar la composición química y las propiedades físicas de un material, para obtener calidadesóptimas en un determinado proceso; además es posible obtener las bases de datos de parámetros del arco eléctrico útilespara investigar, desarrollar y valorar métodos y algoritmos para el monitoreo en tiempo real de la calidad de la soldaduradurante un determinado proceso tecnológico de soldadura con arco eléctrico.Palabras Clave: Ensayo, materiales, soldadura, arco eléctrico, estabilidad, calidad, simulación, optimización,unión soldada.___________________________________________________________________________Abstract.This paper presenst an integral, flexible and shaped method that make easy the electric arc welding consumable materials test at thedesigned technological conditions, related to the quality of the welding joint. It is possible to arrive to definitive conclusions about thewelding quality using a fixed material through: operational
Point- and curve-based geometric conflation
López-Vázquez, C.
2013-01-01
Geometric conflation is the process undertaken to modify the coordinates of features in dataset A in order to match corresponding ones in dataset B. The overwhelming majority of the literature considers the use of points as features to define the transformation. In this article we present a procedure to consider one-dimensional curves also, which are commonly available as Global Navigation Satellite System (GNSS) tracks, routes, coastlines, and so on, in order to define the estimate of the displacements to be applied to each object in A. The procedure involves three steps, including the partial matching of corresponding curves, the computation of some analytical expression, and the addition of a correction term in order to satisfy basic cartographic rules. A numerical example is presented. © 2013 Copyright Taylor and Francis Group, LLC.
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
LIANG; Ke(
2001-01-01
［1］Vogan, D. , Dixmier algebras, sheets and representation theory (in Actes du colloque en I' honneur de Jacques Dixmier),Progress in Math. 92, Boston: Birkhauser Verlag, 1990, 333－397.［2］McGovern, W., Dixmier Algebras and Orbit Method, Operator Algebras, Unitary Representations and Invariant Theory,Boston: Birkhauser, 1990, 397－416.［3］Liang, K. , Parabolic inductions of nilpotent geometric orbit datum, Chinese Science Bulletin (in Chinese) , 1996, 41 (23):2116－2118.［4］Vogan, D., Representations of Real Reductive Lie Groups, Boston-Basel-Stuttgart: Birkhauser, 1981.［5］Lustig, G., Spaltenstein, N., Induced unipotent class, J. London Math. Soc., 1997, 19. 41－52.［6］Collingwood, D. H. , McGovern, W. M. , Nilpotent Orbits in Semisimple Lie Algebras, New York: Van Nostremt Reinhold,1993.
Geometrically induced magnetic catalysis and critical dimensions
Flachi, Antonino; Vitagliano, Vincenzo
2015-01-01
We discuss the combined effect of magnetic fields and geometry in interacting fermionic systems. At leading order in the heat-kernel expansion, the infrared singularity (that in flat space leads to the magnetic catalysis) is regulated by the chiral gap effect and the catalysis is deactivated by effect of the curvature. We discover that an infrared singularity may reappear from higher-order terms in the heat kernel expansion leading to a novel form of geometrically induced magnetic catalysis (absent in flat space). The dynamical mass squared is then modified not only due to the chiral gap effect by an amount proportional to the curvature, but also by a magnetic shift $\\propto (4-D)eB$ where $D$ represents the number of space-time dimensions. We argue that $D=4$ is a critical dimension across which the behaviour of the magnetic shift changes qualitatively.
Locally localized gravity and geometric transitions
Energy Technology Data Exchange (ETDEWEB)
Bazeia, Dionisio [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil)]. E-mail: bazeia@fisica.ufpb.br; Brito, Francisco A. [Departamento de Fisica, Universidade Federal de Campina Grande, 58109-970 Campina Grande, Paraiba (Brazil); Gomes, Adalto Rodrigues [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil); Departamento de Ciencias Exatas, Centro Federal de Educacao Tecnologica do Maranhao, 65025-001 Sao Luis, Maranhao (Brazil)
2004-11-01
In this paper we analyze the local localization of gravity in AdS{sub 4} thick brane embedded in AdS{sub 5} space. The 3-brane is modelled by domain wall solution of a theory with a bulk scalar field coupled to five-dimensional gravity. In addition to small four-dimensional cosmological constant, the vacuum expectation value (vev) of the scalar field controls the emergence of a localized four-dimensional quasi-zero mode. We introduce high temperature effects, and we show that gravity localization on a thick 3-brane is favored below a critical temperature T{sub c}. These investigations suggest the appearance of another critical temperature T*, where the thick 3-brane engenders the geometric (author)
Sectorization and Configuration Transition in Airspace Design
Directory of Open Access Journals (Sweden)
Xiang Zou
2016-01-01
Full Text Available Current airspace is sectorized according to some predefined rules that are not flexible. To facilitate utilizing the airspace more efficiently, methods to design sectors need to be promoted. In this paper, we propose an undirected graph cut-based approach that employs a memetic local search-embedded constrained evolution algorithm, NSGA-II, to generate nondominated airspace configurations. We also propose a new concave hull-based method to automatically depict sector boundaries. In addition, we also study the configuration transition problem. We define the similarity of the two different configurations and calculate their similarity with a bisection diagram and a minimum cost flow algorithm. We build a forward network to represent configuration transitions across several consecutive time periods and use multiobjective dynamic programming to determine a series of nondominated configuration links from the first period to the end. We test our approaches by simulation in high-altitude airspace controlled by Beijing Area Control Center. The results show that our sectorization method outperforms the current configuration in practice, providing a lower sector number, lower intersector flow, more balanced workload distribution among the different sectors, and no constraint violations, so that the proposed approach shows its significant potential as practical applications for dynamic airspace configuration.
Variation in avian brain shape: relationship with size and orbital shape.
Kawabe, Soichiro; Shimokawa, Tetsuya; Miki, Hitoshi; Matsuda, Seiji; Endo, Hideki
2013-11-01
There is wide variation in brain shape among birds. Differences in brain dimensions reflect species-specific sensory capacities and behavioral repertoires that are shaped by environmental and biological factors during evolution. Most previous studies aimed at defining factors impacting brain shape have used volumetric or linear measurements. However, few have explored the quantitative indices of three-dimensional (3D) brain geometry that are absolutely imperative to understanding avian evolutionary history. This study aimed: (i) to explore the relationship between brain shape and overall brain size; and (ii) to assess the relationship between brain shape and orbital shape. Avian brain endocasts were reconstructed from computed tomography images and analyzed using 3D geometric morphometrics. Principal component analysis revealed dominant regional variations in avian brain shape and shape correlations between the telencephalon and cerebellum, between the cerebellum and myelencephalon, and between the diencephalon and optic tectum. Brain shape changes relative to total brain size were determined by multivariate regression analysis. Larger brain size was associated with a relatively slender telencephalon and differences in brain orientation. The correlation between brain shape and orbital shape was assessed by two-block partial least-squares analysis. Relatively round brains with a ventrally flexed brain base were associated with rounder orbits, while narrower brains with a flat brain base were associated with more elongated orbits. The shapes of functionally associated avian brain regions are correlated, and orbital size and shape are dominant factors influencing the overall shape of the avian brain.
Bodily, Kent D; Kilday, Zachary A; Eastman, Caroline K; Gaskin, Katherine A; Graves, April A; Roberts, Jonathan E; Sturz, Bradley R
2013-02-01
In the reorientation literature, non-geometric cues include discrete objects (e.g., beacons) and surface-based features (e.g., colors, textures, and odors). To date, these types of non-geometric cues have been considered functionally similar, and it remains unknown whether beacons and surface features differentially influence the extent to which organisms reorient via global and local geometric cues. In the present experiment, we trained human participants to approach a location in a trapezoid-shaped enclosure uniquely specified by global and local geometric cues. We explored the role of beacons on the use of geometric cues by training participants in the presence or absence of uniquely-colored beacons. We explored the role of surface features on the use of geometric cues by recoloring two adjacent walls at the correct location and/or adding a line on the floor which corresponded to the major principal axis of the enclosure. All groups were then tested in novel-shaped enclosures in the absence of unique beacons and surface features to assess the relative use of global and local geometric cues. Results suggested that beacons facilitated the use of global geometric cues, whereas surface features either facilitated or hindered the use of geometric cues, depending on the feature. Published by Elsevier B.V.
Forecasting and Evaluation of Gas Pipelines Geometric Forms Breach Hazard
Voronin, K. S.
2016-10-01
Main gas pipelines during operation are under the influence of the permanent pressure drops which leads to their lengthening and as a result, to instability of their position in space. In dynamic systems that have feedback, phenomena, preceding emergencies, should be observed. The article discusses the forced vibrations of the gas pipeline cylindrical surface under the influence of dynamic loads caused by pressure surges, and the process of its geometric shape deformation. Frequency of vibrations, arising in the pipeline at the stage preceding its bending, is being determined. Identification of this frequency can be the basis for the development of a method of monitoring the technical condition of the gas pipeline, and forecasting possible emergency situations allows planning and carrying out in due time reconstruction works on sections of gas pipeline with a possible deviation from the design position.
Polyakov, Felix
2017-02-01
Neuroscientific studies of drawing-like movements usually analyze neural representation of either geometric (e.g., direction, shape) or temporal (e.g., speed) parameters of trajectories rather than trajectory's representation as a whole. This work is about identifying geometric building blocks of movements by unifying different empirically supported mathematical descriptions that characterize relationship between geometric and temporal aspects of biological motion. Movement primitives supposedly facilitate the efficiency of movements' representation in the brain and comply with such criteria for biological movements as kinematic smoothness and geometric constraint. The minimum-jerk model formalizes criterion for trajectories' maximal smoothness of order 3. I derive a class of differential equations obeyed by movement paths whose nth-order maximally smooth trajectories accumulate path measurement with constant rate. Constant rate of accumulating equi-affine arc complies with the 2/3 power-law model. Candidate primitive shapes identified as equations' solutions for arcs in different geometries in plane and in space are presented. Connection between geometric invariance, motion smoothness, compositionality and performance of the compromised motor control system is proposed within single invariance-smoothness framework. The derived class of differential equations is a novel tool for discovering candidates for geometric movement primitives.
Geometric decompositions of collective motion
Mischiati, Matteo; Krishnaprasad, P. S.
2017-04-01
Collective motion in nature is a captivating phenomenon. Revealing the underlying mechanisms, which are of biological and theoretical interest, will require empirical data, modelling and analysis techniques. Here, we contribute a geometric viewpoint, yielding a novel method of analysing movement. Snapshots of collective motion are portrayed as tangent vectors on configuration space, with length determined by the total kinetic energy. Using the geometry of fibre bundles and connections, this portrait is split into orthogonal components each tangential to a lower dimensional manifold derived from configuration space. The resulting decomposition, when interleaved with classical shape space construction, is categorized into a family of kinematic modes-including rigid translations, rigid rotations, inertia tensor transformations, expansions and compressions. Snapshots of empirical data from natural collectives can be allocated to these modes and weighted by fractions of total kinetic energy. Such quantitative measures can provide insight into the variation of the driving goals of a collective, as illustrated by applying these methods to a publicly available dataset of pigeon flocking. The geometric framework may also be profitably employed in the control of artificial systems of interacting agents such as robots.
Gheorghiu, Tamara; Vacaru, Olivia; Vacaru, Sergiu I
2016-01-01
We study geometric relativistic flow and Ricci soliton equations which (for respective nonholonomic constraints and self-similarity conditions) are equivalent to the gravitational field equations of $R^2$ gravity and/or to the Einstein equations with scalar field in general relativity, GR. Perelman's functionals are generalized for modified gravity theories, MGTs, which allows to formulate an analogous statistical thermodynamics for geometric flows and Ricci solitons. There are constructed and analyzed generic off-diagonal black ellipsoid, black hole and solitonic exact solutions in MGTs and GR encoding geometric flow evolution scenarios and nonlinear parametric interactions. Such new classes of solutions in MGTs can be with polarized and/or running constants, nonholonomically deformed horizons and/or imbedded self-consistently into solitonic backgrounds. They exist also in GR as generic off-diagonal vacuum configurations with effective cosmological constant and/or mimicking effective scalar field interaction...
Geometrical and computer modeling of mechanical engineering surfaces products intersection line
Panchuk, K. L.; Kaygorodtseva, N. V.; Kaygorodtseva, T. N.; Yurkov, V. Yu
2017-06-01
In the design and manufacture of engineering products geometrical problem is known by shaping the surface of the product. An important element of general solution of this problem is to define the lines of surfaces intersection, forming the shape of designed product. Existing possibilities of modern CAD systems do not allow achieving fullness of the result in this direction. For example, control points and change point of visibility is difficult to identify in the product drawings. In addition, there are no possibilities of detecting imaginary points which are necessary for a complete analysis of intersection surfaces, and mapping these points in the drawing. The aim of the study is to develop a geometric algorithm of constructive determining the intersection line and is devoid of these shortcomings. The objectives of the study are testing the obtained algorithm by experimental verification with geometric modeling solutions to specific problems by tools CAD. This study adopted the method, which is based on quotient of geometric sets, which are regarded as intersecting surfaces in space E3 . One area of practical use of surface engineering products geometric algorithm - shaping is based on their intersection line.
Topological and differential geometrical gauge field theory
Saaty, Joseph
between bosons (quantized) and fermions (not quantized). Thus I produced results that were previously unobtainable. Furthermore, since topological charge takes place in Flat Spacetime, I investigated the quantization of the Curved Spacetime version of topological charge (Differential Geometrical Charge) by developing the differential geometrical Gauge Field Theory. It should be noted that the homotopy classification method is not at all applicable to Curved Spacetime. I also modified the Dirac equation in Curved Spacetime by using Einstein's field equation in order to account for the presence of matter. As a result, my method has allowed me to address four cases of topological charge (both spinless and spin one- half, in both Flat and in Curved Spacetime) whereas earlier methods had been blind to all but one of these cases (spinless in Flat Spacetime). (Abstract shortened by UMI.)
Directory of Open Access Journals (Sweden)
Emilio Tibaldi
2010-01-01
Full Text Available The effect of the farming system on biometry traits and dressing out yield were inves- tigated in market-size European sea bass (Dicentrarchus labrax cultured extensively or intensively in sea cages or land-based basins. Fish external appearences and shapes were studies with geometric morphometrics in order to assess the potential of combined methodologies in the assessment of finfish quality. Both standard biometry and geometric morphometrics were able to discriminate between sea bass farmed extensively from those cultured under intensive conditions. Geometric morphometrics has been shown to be a valuable tool for describing changes in shape features and could result a useful technique to be associated to biometry traits in the context of fish quality assessment.
Field configuring events shaping sustainability transitions? The case of solar PV in India
Jolly, Suyash; Raven, R.P.J.M.
2016-01-01
Abstract The sustainability transitions literature has emphasized the analytical challenges in understanding the trade-offs in protecting niche innovations. This paper builds on an emerging body of literature that argues that the concept of field-configuring events (FCE) is useful for understanding
Geometric and Textural Blending for 3D Model Stylization.
Huang, YiJheng; Lin, Wen-Chieh; Yeh, I-Cheng; Lee, Tong-Yee
2017-01-25
Stylizing a 3D model with characteristic shapes or appearances is common in product design, particularly in the design of 3D model merchandise, such as souvenirs, toys, furniture, and stylized items. A model stylization approach is proposed in this study. The approach combines base and style models while preserving user-specified shape features of the base model and the attractive features of the style model with limited assistance from a user. The two models are first combined at the topological level. A tree-growing technique is utilized to search for all possible combinations of the two models. Second, the models are combined at textural and geometric levels by employing a morphing technique. Results show that the proposed approach generates various appealing models and allows users to control the diversity of the output models and adjust the blending degree between the base and style models. The results of this work are also experimentally compared with those of a recent work through a user study. The comparison indicates that our results are more appealing, feature-preserving, and reasonable than those of the compared previous study. The proposed system allows product designers to easily explore design possibilities and assists novice users in creating their own stylized models.
Quasistatic analysis on configuration of two-phase flow in Y-shaped tubes
Zhong, Hua
2014-12-01
We investigate the two-phase flow in a horizontally placed Y-shaped tube with different Young\\'s angle and width in each branch. By using a quasistatic approach, we can determine the specific contact position and the equilibrium contact angle of fluid in each branch based on the minimization problem of the free energy of the system. The wettability condition and the width of the two branches play important roles in the distribution of fluid in each branch. We also consider the effect of gravity. Some fluid in the upper branch will be pulled down due to the competition of the surface energy and the gravitational energy. The result provides some insights on the theory of two-phase flow in porous media. In particular, it highlights that the inhomogeneous wettability distribution affects the direction of the fluid penetrating a given porous medium domain. It also sheds light on the current debate whether relative permeability may be considered as a full tensor rather than a scalar.
Reference frame for Product Configuration
DEFF Research Database (Denmark)
Ladeby, Klaes Rohde; Oddsson, Gudmundur Valur
2011-01-01
on configuration systems in the shape of anecdotal reporting on the development of information systems that perhaps support the configuration task – perhaps not. Consequently, the definition of configuration has become ambiguous as different research groups defines configuration differently. This paper propose...... a reference frame for configuration that permits 1) a more precise understanding of a configuration system, 2) a understanding of how the configuration system relate to other systems, and 3) a definition of the basic concepts in configuration. The total configuration system, together with the definition...
Geometric perturbation theory and plasma physics
Energy Technology Data Exchange (ETDEWEB)
Omohundro, S.M.
1985-04-04
Modern differential geometric techniques are used to unify the physical asymptotics underlying mechanics, wave theory and statistical mechanics. The approach gives new insights into the structure of physical theories and is suited to the needs of modern large-scale computer simulation and symbol manipulation systems. A coordinate-free formulation of non-singular perturbation theory is given, from which a new Hamiltonian perturbation structure is derived and related to the unperturbed structure. The theory of perturbations in the presence of symmetry is developed, and the method of averaging is related to reduction by a circle group action. The pseudo-forces and magnetic Poisson bracket terms due to reduction are given a natural asymptotic interpretation. Similar terms due to changing reference frames are related to the method of variation of parameters, which is also given a Hamiltonian formulation. These methods are used to answer a question about nearly periodic systems. The answer leads to a new secular perturbation theory that contains no ad hoc elements. Eikonal wave theory is given a Hamiltonian formulation that generalizes Whitham's Lagrangian approach. The evolution of wave action density on ray phase space is given a Hamiltonian structure using a Lie-Poisson bracket. The relationship between dissipative and Hamiltonian systems is discussed. A new type of attractor is defined which attracts both forward and backward in time and is shown to occur in infinite-dimensional Hamiltonian systems with dissipative behavior. The theory of Smale horseshoes is applied to gyromotion in the neighborhood of a magnetic field reversal and the phenomenon of reinsertion in area-preserving horseshoes is introduced. The central limit theorem is proved by renormalization group techniques. A natural symplectic structure for thermodynamics is shown to arise asymptotically from the maximum entropy formalism.
Quality and food network configuration
DEFF Research Database (Denmark)
Kjeldsen, Chris; Noe, Egon
The aim of the paper is to analyze how the emergence of distinct quality conventions relates to particular network relations within two selected Danish organic dairy enterprises. The paper starts out from the assumption that the distinct qualities, which distinguish organic food, can be viewed...... is thus extremely important and even more so if the product chain in question is a ‘high-quality’ food chain of a relatively high level of complexity, such as an organic food network. Analytically, our main focus is on the relation between network structure and the qualities mediated from cow to cup....... The paper is based on case studies of two Danish dairy enterprises (Thise Dairy and Arla Foods), which all operate within the Danish 'high-quality' and organic food market....
Austerity and Geometric Structure of Field Theories
Kheyfets, Arkady
The relation between the austerity idea and the geometric structure of the three basic field theories- -electrodynamics, Yang-Mills theory, and general relativity --is studied. The idea of austerity was originally suggested by J. A. Wheeler in an attempt to formulate the laws of physics in such a way that they would come into being only within "the gates of time" extending from big bang to big crunch, rather than exist from everlasting to everlasting. One of the most significant manifestations of the austerity idea in field theories is thought to be expressed by the boundary of a boundary principle (BBP). The BBP says that almost all content of the field theories can be deduced from the topological identity (PAR-DIFF)(CCIRC)(PAR -DIFF) = 0 used twice, at the 1-2-3-dimensional level (providing the homgeneous field equations), and at the 2-3-4-dimensional level (providing the conservation laws for the source currents). There are some difficulties in this line of thought due to the apparent lack of universality in application of the BBP to the three basic modern field theories--electrodynamics, Yang-Mills theory, and general relativity. This dissertation: (a) analyses the difficulties by means of algebraic topology, integration theory and modern differential geometry based on the concepts of principal bundles and Ehresmann connections; (b) extends the BBP to the unified Kaluza-Klein theory; (c) reformulates the inhomogeneous field equations and the BBP in terms of E. Cartan moment of rotation, in the way universal for all the three theories and compatible with the original austerity idea; (d) underlines the important role of the soldering structure on spacetime, and indicates that the future development of the austerity idea would involve the generalized theories, including the soldering form as a dynamical variable rather than as a background structure.
Geometric control theory and sub-Riemannian geometry
Boscain, Ugo; Gauthier, Jean-Paul; Sarychev, Andrey; Sigalotti, Mario
2014-01-01
This volume presents recent advances in the interaction between Geometric Control Theory and sub-Riemannian geometry. On the one hand, Geometric Control Theory used the differential geometric and Lie algebraic language for studying controllability, motion planning, stabilizability and optimality for control systems. The geometric approach turned out to be fruitful in applications to robotics, vision modeling, mathematical physics etc. On the other hand, Riemannian geometry and its generalizations, such as sub-Riemannian, Finslerian geometry etc., have been actively adopting methods developed in the scope of geometric control. Application of these methods has led to important results regarding geometry of sub-Riemannian spaces, regularity of sub-Riemannian distances, properties of the group of diffeomorphisms of sub-Riemannian manifolds, local geometry and equivalence of distributions and sub-Riemannian structures, regularity of the Hausdorff volume.
Geometric analysis of the talus and development of a generic talar prosthetic.
Trovato, Alexandra; El-Rich, Marwan; Adeeb, Samer; Dhillon, Suki; Jomha, Nadr
2017-06-01
Trauma to the talus can result in fracture, avascular necrosis and structural collapse. Treatment has been limited to surgical fusion and total ankle arthroplasty. Total ankle arthroplasty may not be an appropriate treatment for avascular necrosis while surgical fusion of the joint limits mobility. Custom-made implants have recently been used to address these limitations but have lengthy delays between injury and surgery and higher associated costs. A generic talar prosthesis available in various sizes may serve as a suitable alternative. The geometric variation between shapes of individual tali was determined using 3D geometric models of 91 tali created from CT-scan data. Comparisons were done to determine if tali are one shape. The best shape was determined for each sex, and was compared to determine if a unisex implant would be possible. A geometric template for the implant in multiple sizes was created and compared to the models. The average of the average deviation between tali after volume scaling was found to be less than 1mm on the main articulating surfaces. One shape group was found for the talus. The female and male tali were found to be similar and a unisex implant template was created. Ten generic talar implant sizes were determined to be sufficient to match the size and shape of the 91 tali examined in this study. Copyright © 2016 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Geometrical Description of Quantum Mechanics - Transformations and Dynamics
Marmo, G.; Volkert, G. F.
2010-01-01
In this paper we review a proposed geometrical formulation of quantum mechanics. We argue that this geometrization makes available mathematical methods from classical mechanics to the quantum frame work. We apply this formulation to the study of separability and entanglement for states of composite quantum systems.
Developing a Network of and for Geometric Reasoning
Mamolo, Ami; Ruttenberg-Rozen, Robyn; Whiteley, Walter
2015-01-01
In this article, we develop a theoretical model for restructuring mathematical tasks, usually considered advanced, with a network of spatial visual representations designed to support geometric reasoning for learners of disparate ages, stages, strengths, and preparation. Through our geometric reworking of the well-known "open box…
Creativity and Motivation for Geometric Tasks Designing in Education
Rumanová, Lucia; Smiešková, Edita
2015-01-01
In this paper we focus on creativity needed for geometric tasks designing, visualization of geometric problems and use of ICT. We present some examples of various problems related to tessellations. Altogether 21 students--pre-service teachers participated in our activity within a geometry course at CPU in Nitra, Slovakia. Our attempt was to…
Morse Theory and the Geometric interpretation of NCCW Complexes
Milani, Vida; Rezaei, Ali Asghar
2009-01-01
The approach we present here is a modification of the Morse theory for unital C*-algebras.It helps us to study the geometry of the noncommutative CW complexes introduced in[1] and [2]. A geometric condition for a unital C*-algebra to admit a noncommutative CW complex decomposition is studied. Some examples to illustrate these geometric information in practice are given.
Lee, Sukyung; Chung, Jihoon; Kim, Dae Yun; Jung, Jung-Yeul; Lee, Seong Hyuk; Lee, Sangmin
2016-09-28
We demonstrate a cylindrical water triboelectric nanogenerator (CW-TENG) that generates sustainable electrical output. The inner surface of the cylinder was patterned into superhydrophobic and hydrophilic parts to control water flow inside the packaged design of CW-TENG. Here, various thicknesses and roughnesses of the superhydrophobic surface, generated using aluminum oxide nanostructures for enhanced electrostatic induction, were measured to obtain the maximum output and superhydrophobicity. Also, we demonstrate the possibility of using a hydrophilic surface for energy harvesting and as a water reservoir in the packaged design.
Geometric Calibration and Accuracy Verification of the GF-3 Satellite.
Zhao, Ruishan; Zhang, Guo; Deng, Mingjun; Xu, Kai; Guo, Fengcheng
2017-08-29
The GF-3 satellite is the first multi-polarization synthetic aperture radar (SAR) imaging satellite in China, which operates in the C band with a resolution of 1 m. Although the SAR satellite system was geometrically calibrated during the in-orbit commissioning phase, there are still some system errors that affect its geometric positioning accuracy. In this study, these errors are classified into three categories: fixed system error, time-varying system error, and random error. Using a multimode hybrid geometric calibration of spaceborne SAR, and considering the atmospheric propagation delay, all system errors can be effectively corrected through high-precision ground control points and global atmospheric reference data. The geometric calibration experiments and accuracy evaluation for the GF-3 satellite are performed using ground control data from several regions. The experimental results show that the residual system errors of the GF-3 SAR satellite have been effectively eliminated, and the geometric positioning accuracy can be better than 3 m.
Liquid mixing enhanced by pulse width modulation in a Y-shaped jet configuration
Xia, Qingfeng; Zhong, Shan
2013-04-01
In this paper, mixing between two fluid streams, which are injected into a planar mixing channel via a Y-shaped confluence section at the same volume flow rate, is studied experimentally. The injection of the two fluid streams is controlled by two separate solenoid valves, which are operated with a phase difference of 180°, using pulse width modulation. The experiments are conducted using water at a mean Reynolds number between 83 and 250, a range of pulsation frequencies and two duty cycles (25 and 50%). Both particle-image velocimetry and planar laser-induced fluorescence technique are used to visualize the flow patterns and to quantify the mixing degree in the mixing channel. This experiment shows that the pulsation of each jet produces vortical structures, which promotes mixing via vortex entrainment and vortex breakup, and at the same time the mixing is also greatly enhanced by sequential segmentation produced by a 180° out-of-phase pulsation of the two jets. This mixing enhancement method is effective at a Reynolds number greater than 125 with a mixing degree of 0.9 being achieved. For the Reynolds numbers studied in the present experiments, an optimal frequency exists, which corresponds to a Strouhal number in the range of 0.5-2. Furthermore, at a given mean Reynolds number a lower duty cycle is found to produce a better mixing due to the resultant higher instantaneous Reynolds number in the jet flow. It is also found that pulsation of only one jet can produce a similar mixing effect.
Use of Ocean Exploration Learning Shapes (Geometric Solids) to Reinforce Student Inquiry
Keener-Chavis, Paula; Goodwin, Mel
2009-01-01
The implications of Earth's ocean being little explored may not be immediately evident to individuals who are not ocean literate. For this reason, initiatives to improve ocean literacy must articulate compelling reasons for ocean exploration. A lesson plan that addresses this issue has been developed as part of the education and outreach program…
Geometric phase and Pancharatnam phase induced by light wave polarization
Lages, J; Vigoureux, J -M
2013-01-01
We use the quantum kinematic approach to revisit geometric phases associated with polarizing processes of a monochromatic light wave. We give the expressions of geometric phases for any, unitary or non-unitary, cyclic or non-cyclic transformations of the light wave state. Contrarily to the usually considered case of absorbing polarizers, we found that a light wave passing through a polarizer may acquire in general a non zero geometric phase. This geometric phase exists despite the fact that initial and final polarization states are in phase according to the Pancharatnam criterion and can not be measured using interferometric superposition. Consequently, there is a difference between the Pancharatnam phase and the complete geometric phase acquired by a light wave passing through a polarizer. We illustrate our work with the particular example of total reflection based polarizers.
ATLAS software configuration and build tool optimisation
Rybkin, G; The ATLAS collaboration
2014-01-01
ATLAS software code base is over 6 million lines organised in about 2000 packages. It makes use of some 100 external software packages, is developed by more than 400 developers and used by more than 2500 physicists from over 200 universities and laboratories in 6 continents. To meet the challenge of configuration and building of this software, the Configuration Management Tool (CMT) is used. CMT expects each package to describe its build targets, build and environment setup parameters, dependencies on other packages in a text file called requirements, and each project (group of packages) to describe its policies and dependencies on other projects in a text project file. Based on the effective set of configuration parameters read from the requirements files of dependent packages and project files, CMT commands build the packages, generate the environment for their use, or query the packages. The main focus was on build time performance that was optimised within several approaches: reduction of the number of re...
ATLAS software configuration and build tool optimisation
Rybkin, G; The ATLAS collaboration
2013-01-01
ATLAS software code base is over 6 million lines organised in about 2000 packages. It makes use of some 100 external software packages, is developed by more than 400 developers and used by more than 2500 physicists from over 200 universities and laboratories in 6 continents. To meet the challenge of configuration and building of this software, the Configuration Management Tool (CMT) is used. CMT expects each package to describe its build targets, build and environment setup parameters, dependencies on other packages in a text file called requirements, and each project (group of packages) to describe its policies and dependencies on other projects in a text project file. Based on the effective set of configuration parameters read from the requirements files of dependent packages and project files, CMT commands build the packages, generate the environment for their use, or query the packages. The main focus was on build time performance that was optimised within several approaches: reduction of the number of re...
Automated firewall analytics design, configuration and optimization
Al-Shaer, Ehab
2014-01-01
This book provides a comprehensive and in-depth study of automated firewall policy analysis for designing, configuring and managing distributed firewalls in large-scale enterpriser networks. It presents methodologies, techniques and tools for researchers as well as professionals to understand the challenges and improve the state-of-the-art of managing firewalls systematically in both research and application domains. Chapters explore set-theory, managing firewall configuration globally and consistently, access control list with encryption, and authentication such as IPSec policies. The author
Geometrical effective action and Wilsonian flows
Pawlowski, J M
2003-01-01
A gauge invariant flow equation is derived by applying a Wilsonian momentum cut-off to gauge invariant field variables. The construction makes use of the geometrical effective action for gauge theories in the Vilkovisky-DeWitt framework. The approach leads to modified Nielsen identities that pose non-trivial constraints on consistent truncations. We also evaluate the relation of the present approach to gauge fixed formulations as well as discussing possible applications.
CFDP Configuration: Enclid and Juice Scenarios
Valverde, Alberto; Taylor, Chris; Montesinos, Juan Antonio; Maiorano, Elena; Colombo, Cyril; Erd, Christian; Magistrati, Giorgio
2014-08-01
This paper presents the work done within the ESA ESTEC Data Systems Division, targeting the implementation of CFDP in future ESA Science Missions. EUCLID and JUICE currently include CCSDS File Delivery Protocol (CFDP) as baseline for payload data transfer to ground. The two missions have completely different characteristics, although both present quite demanding scenarios. Using the communication link characteristics as an input, some simulations have been performed to optimize the CFDP configuration and get some preliminary figures on the retransmission overhead, payload data bandwidth and number of parallel transactions needed to maintain full bandwidth utilization. The paper provides some guidelines on CFDP configuration and usage that can be useful in future CFDP implementations.
Configurational space continuity and free energy calculations
Tian, Pu
2016-01-01
Free energy is arguably the most importance function(al) for understanding of molecular systems. A number of rigorous and approximate free energy calculation/estimation methods have been developed over many decades. One important issue, the continuity of an interested macrostate (or path) in configurational space, has not been well articulated, however. As a matter of fact, some important special cases have been intensively discussed. In this perspective, I discuss the relevance of configurational space continuity in development of more efficient and reliable next generation free energy methodologies.
Geometrical and physical conditions for skyrmion stability in a nanowire
Directory of Open Access Journals (Sweden)
C. P. Chui
2015-04-01
Full Text Available Skyrmions are promising information carriers in the next-generation storage and transmission devices. Appropriate design of the nanowire that permits the flow of skyrmions is, however, seldom studied. In this work, the geometrical and material parameters have been varied to investigate the favorable conditions for skyrmion formation and stability in a nanowire through micromagnetic simulations. It is found that the minimum planar dimensions have to be satisfied in order to stabilize a skyrmion. Furthermore, the nanowire thickness is also important for establishing a skyrmion. The temperature effect in the competition between the perpendicular magnetic anisotropy (PMA and the Dzyaloshinskii–Moriya interaction (DMI limits the skyrmion formation in a well-defined phase. On the other hand, fine tuning of the exchange stiffness and the Gilbert damping constant sustain a specified portion of the phase diagram that allows for skyrmion formation. Our study also indicates that the stabilized magnetization pattern is dependent on the initial skyrmion state. These results shed light on the possible configurations that are suitable for the design of skyrmionic devices.
Geometric constructions for repulsive gravity and quantization
Energy Technology Data Exchange (ETDEWEB)
Hohmann, Manuel
2010-11-15
In this thesis we present two geometric theories designed to extend general relativity. It can be seen as one of the aims of such theories to model the observed accelerating expansion of the universe as a gravitational phenomenon, or to provide a mathematical structure for the formulation of quantum field theories on curved spacetimes and quantum gravity. This thesis splits into two parts: In the first part we consider multimetric gravity theories containing N>1 standard model copies which interact only gravitationally and repel each other in the Newtonian limit. The dynamics of each of the standard model copies is governed by its own metric tensor. We show that the antisymmetric case, in which the mutual repulsion between the different matter sectors is of equal strength compared to the attractive gravitational force within each sector, is prohibited by a no-go theorem for N=2. We further show that this theorem does not hold for N>2 by explicitly constructing an antisymmetric multimetric repulsive gravity theory. We then examine several properties of this theory. Most notably, we derive a simple cosmological model and show that the accelerating expansion of the late universe can indeed be explained by the mutual repulsion between the different matter sectors. We further present a simple model for structure formation and show that our model leads to the formation of filament-like structures and voids. Finally, we show that multimetric repulsive gravity is compatible with high-precision solar system data using the parametrized post-Newtonian formalism. In the second part of the thesis we propose a mathematical model of quantum spacetime as an infinite-dimensional manifold locally homeomorphic to an appropriate Schwartz space. This extends and unifies both the standard function space construction of quantum mechanics and the differentiable manifold structure of classical spacetime. In this picture we demonstrate that classical spacetime emerges as a finite
Samadi, Reza
Technical textiles are increasingly being engineered and used in challenging applications, in areas such as safety, biomedical devices, architecture and others, where they must meet stringent demands including excellent and predictable load bearing capabilities. They also form the bases for one of the most widespread group of composite materials, fibre reinforced polymer-matrix composites (PMCs), which comprise materials made of stiff and strong fibres generally available in textile form and selected for their structural potential, combined with a polymer matrix that gives parts their shape. Manufacturing processes for PMCs and technical textiles, as well as parts and advanced textile structures must be engineered, ideally through simulation, and therefore diverse properties of the textiles, textile reinforcements and PMC materials must be available for predictive simulation. Knowing the detailed geometry of technical textiles is essential to predicting accurately the processing and performance properties of textiles and PMC parts. In turn, the geometry taken by a textile or a reinforcement textile is linked in an intricate manner to its constitutive behaviour. This thesis proposes, investigates and validates a general numerical tool for the integrated and comprehensive analysis of textile geometry and constitutive behaviour as required toward engineering applications featuring technical textiles and textile reinforcements. The tool shall be general with regards to the textiles modelled and the loading cases applied. Specifically, the work aims at fulfilling the following objectives: 1) developing and implementing dedicated simulation software for modelling textiles subjected to various load cases; 2) providing, through simulation, geometric descriptions for different textiles subjected to different load cases namely compaction, relaxation and shear; 3) predicting the constitutive behaviour of the textiles undergoing said load cases; 4) identifying parameters
Linking Assessment and Instruction Innovation Configuration
Hosp, John L.
2011-01-01
This innovation configuration identifies the skills and competencies teachers need to make sound decisions about using assessment information to improve instruction and establishes a framework and justification for effective ways that teachers can collect and use assessment data to make instructional decisions. It is designed to provide a…
Directory of Open Access Journals (Sweden)
Mahmoudi M.
2011-09-01
Full Text Available Statement of Problem: Researchers are often looking for appropriate treatments while considering esthetic aspects and health. In endodontically treated teeth afflicted with severe damage or complete loss of the coronal structure, a post is usually inserted in the root canal to provide intra-canal retention of the restorations. Therefore, it seems that it is necessary to investigate the stress distribution in the restored teeth with different post algorithms.Purpose: In this study, the effects of post geometry and its dimensions on the stress distributions and levels in the root of molar teeth repaired by post-core crown (Ceramic, Alumina and Nickel-chrome were studied using finite element method. Materials and Method: An extracted intact mandibular second molar tooth was embedded in a cylindrical acrylic resin mould and then were sliced. The sections generated in this way were photographed and the images were transferred into the Solidworks software. After tooth modeling, Posts and crowns were designed. Then, the samples were exposed to a uniform distributed load of 240 N with the load angle of 45 degree which was applied over the occlusal area. In order to simulate the surrounding area of the tooth and also the periodontal ligament space, the bone was also modeled.Results: Numerical results revealed that in the prefabricated post restoration, there was a stress concentration in the cervical region. The maximum value of normal stress (32.3 MPa was seen in the parallel post with 1.4 diameter (D1.4, and the minimum value (26.7 MPa was observed in the double tapered post (N0.1. It was observed that the increase in the modulus of elasticity from 100 to 300 causes an increase in normal stress from 69.5 to 38.5 MPa and in tensile stress from 69.5 to 38.5 MPa.Conclusion: Numerical analysis showed that the maximum stress concentration in post core crown restoration increased when the posts with 1.4 mm diameter or post with double taper were used. The
Multiscale Geometric Analysis: Theory, Applications, and Opportunities
2007-11-02
eiωΦν(x,t) ( a0ν(x, t) + a1ν(x, t) ω + a2ν(x, t) ω2 + . . . ) • Plug into wave equation – Eikonal equations ∂tΦν + λν(x,∇xΦ) = 0. λν(x, k) are the...space ẋ(t) = ∇kλν(x, k), x(0) = x0,k̇(t) = −∇xλν(x, k), k(0) = k0. • Eikonal equations from geometric optics ∂tΦν + λν(x,∇xΦ) = 0. Φ is constant
Geometric covering arguments and ergodic theorems for free groups
Bowen, Lewis
2009-01-01
We present a new approach to the proof of ergodic theorems for actions of free groups based on geometric covering and asymptotic invariance arguments. Our approach can be viewed as a direct generalization of the classical geometric covering and asymptotic invariance arguments used in the ergodic theory of amenable groups. We use this approach to generalize the existing maximal and pointwise ergodic theorems for free group actions to a large class of geometric averages which were not accessible by previous techniques. Some applications of our approach to other groups and other problems in ergodic theory are also briefly discussed.
Coordinate Geometric Generalization of the Spherometer and Cylindrometer
Khan, Sameen Ahmed
2013-01-01
Spherometer is an instrument widely used for measuring the radius of curvature of a spherical surface. Cylindrometer is a modified spherometer, which can measure the radii of both spherical and cylindrical surfaces. Both of these instruments are based on a geometric relation unique to circles and spheres, from Euclidean geometry. A more general understanding is obtained using coordinate geometry. The coordinate geometric approach also enables a generalization of the spherometer and cylindrometer to devices, which can handle aspherical surfaces. Here, we present the newly developed coordinate geometric approach and its applications.
Quaternionen and Geometric Algebra (Quaternionen und Geometrische Algebra)
Horn, Martin Erik
2007-01-01
In the last one and a half centuries, the analysis of quaternions has not only led to further developments in mathematics but has also been and remains an important catalyst for the further development of theories in physics. At the same time, Hestenes geometric algebra provides a didactically promising instrument to model phenomena in physics mathematically and in a tangible manner. Quaternions particularly have a catchy interpretation in the context of geometric algebra which can be used didactically. The relation between quaternions and geometric algebra is presented with a view to analysing its didactical possibilities.
Specification and Configuration of Customized Complex Products
Afsarmanesh, H.; Shafahi, M.
2013-01-01
This paper addresses the design of an information system for specification of complex configured products, such as the solar power plants or large intelligent buildings, which by nature are designed, constructed, installed, operated, and maintained through virtual consortium of enterprises. In other
Stimulus Configuration, Classical Conditioning, and Hippocampal Function.
Schmajuk, Nestor A.; DiCarlo, James J.
1991-01-01
The participation of the hippocampus in classical conditioning is described in terms of a multilayer network portraying stimulus configuration. A model of hippocampal function is presented, and computer simulations are used to study neural activity in the various brain areas mapped according to the model. (SLD)
Configuration and Data Management Process and the System Safety Professional
Shivers, Charles Herbert; Parker, Nelson C. (Technical Monitor)
2001-01-01
This article presents a discussion of the configuration management (CM) and the Data Management (DM) functions and provides a perspective of the importance of configuration and data management processes to the success of system safety activities. The article addresses the basic requirements of configuration and data management generally based on NASA configuration and data management policies and practices, although the concepts are likely to represent processes of any public or private organization's well-designed configuration and data management program.
"Geometric" planetology and origin of the Moon
Kochemasov, Gennady G.
2010-05-01
The comparative wave planetology [1 & othres] demonstrates graphically its main conceptual point: orbits make structures. The structures are produced by a warping action of stationary waves induced in bodies by non-circular orbits with periodically changing bodies' accelerations. A geometric model of tectonic granulation of planets is a schematic row of even circles adorned with granules radius of which increases in direction from Sun to the outer planets. It was shown that the granule radii are inversely proportional to the orbital frequencies of planets. Thus, there is a following row of these radii: Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. It was also shown that these radii well correlate with planetary surface "ruggedness". This observation led to a conception of the "relief-forming potential of planets"[2]. So, this potential is rather weak in Mercury and Venus, rather high in Mars and intermediate in Earth. Certainly, orbital eccentricities were even higher at the earlier period of planet formation, at debris zones of their accretion causing scattering debris material. This scattering was small at Mercury' and Venus' zones, large at the Mars' zone and intermediate at the Earth's zone. Consequently, gravity kept debris in the first zones, allowed them escape in the martian zone, and allowed to have separated debris sub zone in the vicinity of the Earth's zone or around not fully consolidated (accreted) Earth. Rejecting the giant impact hypotheses of Moon formation as contradicting the fact of the ubiquitous wave induced tectonic dichotomy of celestial bodies (Theorem1 [3]) one should concentrate at hypotheses dealing with formation of the satellite from primordial debris in a near-Earth heliocentric orbit or in a circumterrestrial orbit from debris wave separated from the Earth' zone of accretion. Wave scattering of primordial material from an accretion zone or from a not fully accreted (consolidated) body is a normal process
Burgess, Claudia R.
2014-01-01
Designed for a broad audience, including educators, camp directors, afterschool coordinators, and preservice teachers, this investigation aims to help individuals experience mathematics in unconventional and exciting ways by engaging them in the physical activity of building geometric shapes using ropes. Through this engagement, the author…
Directory of Open Access Journals (Sweden)
Queenilyn B. Albutra
2012-06-01
Full Text Available Rice stem borers are considered as the most serious insect pest of rice in Asia. It infects itsplant host by burrowing into the stem using its mandible. However, apart from the mandible, the head ofrice stem borers is also associated in the incursion process since it facilitates the entry of larvae to the riceplant. Differences in the head capsules have a direct effect on the ability of the insects to ingest hardfoods rapidly. Different rice varieties in the Philippines serve as plant host for this pest and infestationoccurred in different geographical location. Variations in habitat and plant host were thought to generateenvironmental variation in morphometric traits and host adapted herbivore phenotype respectively.Landmark based geometric morphometric analysis was used to assess the hypothesis that the head shapeof white stem borer differ between populations with respect to different rice varieties and geographicallocation where it was obtained. Relative warp analysis showed variation in the head shape betweendifferent white stem borer (Schirpophaga innotata Walker populations infesting different varieties of rice.Non-significant head shape variations were obtained between geographically separated populations. Theseresults indicate that the rice host varieties play an important role in the selection of individuals that areable to counteract the resistance factors in plants.
Haptic spatial configuration learning in deaf and hearing individuals.
Directory of Open Access Journals (Sweden)
Rick van Dijk
Full Text Available The present study investigated haptic spatial configuration learning in deaf individuals, hearing sign language interpreters and hearing controls. In three trials, participants had to match ten shapes haptically to the cut-outs in a board as fast as possible. Deaf and hearing sign language users outperformed the hearing controls. A similar difference was observed for a rotated version of the board. The groups did not differ, however, on a free relocation trial. Though a significant sign language experience advantage was observed, comparison to results from a previous study testing the same task in a group of blind individuals showed it to be smaller than the advantage observed for the blind group. These results are discussed in terms of how sign language experience and sensory deprivation benefit haptic spatial configuration processing.
Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints
Directory of Open Access Journals (Sweden)
Heng Zhang
2015-06-01
Full Text Available A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM. The visual feature is encoded with BRAND (binary robust appearance and normals descriptor, which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset.
Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints.
Zhang, Heng; Liu, Yanli; Tan, Jindong
2015-06-19
A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM). The visual feature is encoded with BRAND (binary robust appearance and normals descriptor), which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH) technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset.
Segal-Bargmann-Hall Transform and Geometric Quantization
Institute of Scientific and Technical Information of China (English)
刘卫平; 王正栋; 胡大鹏
2003-01-01
@@ Using geometric methods, Hall has proved that the Segal-Bargmann transform for a con-nected Lie group K of compact type is an isometric isomorphism [H1] and is unique when Kis simply connected [H7].
Spectral properties and geometric interpretation of R-filters
Institute of Scientific and Technical Information of China (English)
Tuo LENG
2009-01-01
By applying the Fourier analysis, we study the spectral properties of R-filters. Further, we prove that R-filters are a generalization of least squares polynomial adjustment, and we give the geometric interpretation of R-filters.
Brezillon, J.; Dwight, R.P.
2009-01-01
Within the next few years, numerical shape optimization based on high fidelity methods is likely to play a strategic role in future aircraft design. In this context, suitable tools have to be developed for solving aerodynamic shape optimization problems, and the adjoint approach - which allows fast
Geometric and spectral consequences of curvature bounds on tessellations
Keller, Matthias
2016-01-01
This is a chapter of a forthcoming Lecture Notes in Mathematics "Modern Approaches to Discrete Curvature" edited by L. Najman and P. Romon. It provides a survey on geometric and spectral consequences of curvature bounds. The geometric setting are tessellations of surfaces with finite and vanishing genus. We consider a curvature arising as an angular defect. Several of the results presented here have analogues in Riemannian geometry. In some cases one can go even beyond the Riemannian results ...
Lexan Linear Shaped Charge Holder with Magnets and Backing Plate
Maples, Matthew W.; Dutton, Maureen L.; Hacker, Scott C.; Dean, Richard J.; Kidd, Nicholas; Long, Chris; Hicks, Robert C.
2013-01-01
A method was developed for cutting a fabric structural member in an inflatable module, without damaging the internal structure of the module, using linear shaped charge. Lexan and magnets are used in a charge holder to precisely position the linear shaped charge over the desired cut area. Two types of charge holders have been designed, each with its own backing plate. One holder cuts fabric straps in the vertical configuration, and the other charge holder cuts fabric straps in the horizontal configuration.
Aerodynamic effects of simulated ice shapes on two-dimensional airfoils and a swept finite tail
Alansatan, Sait
An experimental study was conducted to investigate the effect of simulated glaze ice shapes on the aerodynamic performance characteristics of two-dimensional airfoils and a swept finite tail. The two dimensional tests involved two NACA 0011 airfoils with chords of 24 and 12 inches. Glaze ice shapes computed with the LEWICE code that were representative of 22.5-min and 45-min ice accretions were simulated with spoilers, which were sized to approximate the horn heights of the LEWICE ice shapes. Lift, drag, pitching moment, and surface pressure coefficients were obtained for a range of test conditions. Test variables included Reynolds number, geometric scaling, control deflection and the key glaze ice features, which were horn height, horn angle, and horn location. For the three-dimensional tests, a 25%-scale business jet empennage (BJE) with a T-tail configuration was used to study the effect of ice shapes on the aerodynamic performance of a swept horizontal tail. Simulated glaze ice shapes included the LEWICE and spoiler ice shapes to represent 9-min and 22.5-min ice accretions. Additional test variables included Reynolds number and elevator deflection. Lift, drag, hinge moment coefficients as well as boundary layer velocity profiles were obtained. The experimental results showed substantial degradation in aerodynamic performance of the airfoils and the swept horizontal tail due to the simulated ice shapes. For the two-dimensional airfoils, the largest aerodynamic penalties were obtained when the 3-in spoiler-ice, which was representative of 45-min glaze ice accretions, was set normal to the chord. Scale and Reynolds effects were not significant for lift and drag. However, pitching moments and pressure distributions showed great sensitivity to Reynolds number and geometric scaling. For the threedimensional study with the swept finite tail, the 22.5-min ice shapes resulted in greater aerodynamic performance degradation than the 9-min ice shapes. The addition of 24
Geometrical and mechanical properties control actin filament organization.
Directory of Open Access Journals (Sweden)
Gaëlle Letort
2015-05-01
Full Text Available The different actin structures governing eukaryotic cell shape and movement are not only determined by the properties of the actin filaments and associated proteins, but also by geometrical constraints. We recently demonstrated that limiting nucleation to specific regions was sufficient to obtain actin networks with different organization. To further investigate how spatially constrained actin nucleation determines the emergent actin organization, we performed detailed simulations of the actin filament system using Cytosim. We first calibrated the steric interaction between filaments, by matching, in simulations and experiments, the bundled actin organization observed with a rectangular bar of nucleating factor. We then studied the overall organization of actin filaments generated by more complex pattern geometries used experimentally. We found that the fraction of parallel versus antiparallel bundles is determined by the mechanical properties of actin filament or bundles and the efficiency of nucleation. Thus nucleation geometry, actin filaments local interactions, bundle rigidity, and nucleation efficiency are the key parameters controlling the emergent actin architecture. We finally simulated more complex nucleation patterns and performed the corresponding experiments to confirm the predictive capabilities of the model.
Non-geometric fluxes and mixed-symmetry potentials
Bergshoeff, E A; Riccioni, F; Risoli, S
2015-01-01
We discuss the relation between generalised fluxes and mixed-symmetry potentials. We first consider the NS fluxes, and point out that the `non-geometric' $R$ flux is dual to a mixed-symmetry potential with a set of nine antisymmetric indices. We then consider the T-duality family of fluxes whose prototype is the Scherk-Schwarz reduction of the S-dual of the RR scalar of IIB supergravity. Using the relation with mixed-symmetry potentials, we are able to give a complete classification of these fluxes, including the ones that are non-geometric. The non-geometric fluxes again turn out to be dual to potentials containing nine antisymmetric indices. Our analysis suggests that all these fluxes can be understood in the context of double field theory, although for the non-geometric ones one expects a violation of the strong constraint.
Geometric Deformations of Orthogonal and Symplectic Galois Representations
Booher, Jeremy
2016-01-01
For a representation over a finite field of characteristic p of the absolute Galois group of the rationals, we study the existence of a lift to characteristic zero that is geometric in the sense of the Fontaine-Mazur conjecture. For two-dimensional representations, Ramakrishna proved that under technical assumptions odd representations admit geometric lifts. We generalize this to higher dimensional orthogonal and symplectic representations. The key innovation is the definition and study of a ...
Trees, Tight-Spans and Point Configuration
Herrmann, Sven
2011-01-01
Tight-spans of metrics were first introduced by Isbell in 1964 and rediscovered and studied by others, most notably by Dress who gave them this name. Subsequently, it was found that tight-spans could be defined for more general maps, such as directed metrics and distances, and more recently for diversities. In this paper, we show that all of these tight-spans can be defined in terms of point configurations. This provides a useful way in which to study these objects in a unified and systematic way. We also show that by using point configurations we can recover results concerning one-dimensional tight-spans for all of the maps we consider, as well as extend these and other results to more general maps such as symmetric and unsymmetric maps.
Stiller, Peter F.
2004-10-01
Recent progress in shape theory, including the development of object/image equations for shape matching and shape space metrics (especially object/image metrics), is now being exploited to develop new algorithms for target recognition. This theory makes use of advanced mathematical techniques from algebraic and differential geometry to construct generalized shape spaces for various projection and sensor models, and then uses that construction to find natural metrics that express the distance (difference) between two configurations of object features, two configurations of image features, or an object and an image pair. Such metrics produce the most robust tests for target identification; at least as far as target geometry is concerned. Moreover, they also provide the basis for efficient hashing schemes to do target identification quickly and provide a rigorous foundation for error analysis in ATR.
AstroSat – Configuration and Realization
Indian Academy of Sciences (India)
K. H. Navalgund; K. Suryanarayana Sarma; Piyush Kumar Gaurav; G. Nagesh; M. Annadurai
2017-06-01
AstroSat is India’s first space-based observatory satellite dedicated to astronomy. It has the capability to perform multi-wavelength and simultaneous observations of cosmic bodies in a wide band of wavelengths. This paper briefly summarizes the challenges faced in the configuration of AstroSat spacecraft, accommodation and sizing of its critical subsystems, their realization and testing of payloads and the integrated satellite.
Institute of Scientific and Technical Information of China (English)
王勇; 张延芳; 陈英华
2014-01-01
The geometric formulation of Euclidean configuration spaces in curvilinear coordinate systems is studied through the first-order linear mapping between the rectangular coordinate system and curvilinear coordinate systems ,and according to the principle of covariance , the motion equation of the particle ,which is the covariant form of Newton’s second law ,can be drawn out .%通过直角坐标系和曲线坐标系之间的一阶线性映射，研究了欧几里得位形空间几何性质在曲线坐标系下的表示。根据协变性原理写出质点在曲线坐标系中的运动方程，该方程是牛顿第二定律的协变形式。
What is the shape of the helium trimer? A comparison with the neon and argon trimers.
Bressanini, Dario; Morosi, Gabriele
2011-10-13
Despite its apparent simplicity and extensive theoretical investigations, the issue of what is the shape of the helium trimer is still debated in the literature. After reviewing previous conflicting interpretations of computational studies, we introduce the angle-angle distribution function as a tool to discuss in a simple way the shape of any trimer. We compute this function along with many different geometrical distributions using variational and diffusion Monte Carlo methods. We compare them with the corresponding ones for the neon and argon trimers. Our analysis shows that while Ne(3) and Ar(3) fluctuate around an equilibrium structure that is an equilateral triangle, (4)He(3) shows an extremely broad angle-angle distribution function, and all kinds of three-atom configurations must be taken into account in its description. Classifying (4)He(3) as either equilateral or linear or any other particular shape, as was done in the past, is not sensible, because in this case the intuitive notion of equilibrium structure is ill defined. Our results could help the interpretation of future experiments aimed at measuring the geometrical properties of the helium trimer.
Non-critical string, Liouville theory and geometric bootstrap hypothesis
Hadasz, L; Hadasz, Leszek; Jaskolski, Zbigniew
2003-01-01
Basing on the standard construction of critical string amplitudes we analyze properties of the longitudinal sector of the non-critical Nambu-Goto string. We demonstrate that it cannot be described by standard (in the sense of BPZ) conformal field theory. As an alternative we propose a new version of the geometric approach to Liouville theory and formulate its basic consistency condition - the geometric bootstrap equation.
Nonadiabatic Geometric Phase in Composite Systems and Its Subsystem
Institute of Scientific and Technical Information of China (English)
LI Xin
2008-01-01
We point out that the time-dependent gauge transformation technique may be effective in investigating the nonadiabatic geometric phase of a subsystem in a composite system. As an example, we consider two uniaxially coupled spin -1/2 particles with one of particles driven by rotating magnetic field. The influences of coupling and precession frequency of the magnetic field on geometric phase are also discussed in detail.
Integration of geometric modeling and advanced finite element preprocessing
Shephard, Mark S.; Finnigan, Peter M.
1987-01-01
The structure to a geometry based finite element preprocessing system is presented. The key features of the system are the use of geometric operators to support all geometric calculations required for analysis model generation, and the use of a hierarchic boundary based data structure for the major data sets within the system. The approach presented can support the finite element modeling procedures used today as well as the fully automated procedures under development.
Equilibrium Configurations of Lipid Bilayer Membranes and Carbon Nanostructures
Institute of Scientific and Technical Information of China (English)
Iva(i)lo M.Mladenov; Peter A.Djondjorov; Mariana Ts.Hadzhilazova; Vassil M.Vassilev
2013-01-01
The present article concerns the continuum modelling of the mechanical behaviour and equilibrium shapes of two types of nano-scale objects:fluid lipid bilayer membranes and carbon nanostructures.A unified continuum model is used to handle four different case studies.Two of them consist in representing in analytic form cylindrical and axisymmetric equilibrium configurations of single-wall carbon nanotubes and fluid lipid bilayer membranes subjected to uniform hydrostatic pressure.The third one is concerned with determination of possible shapes of junctions between a single-wall carbon nanotube and a fiat graphene sheet or another single-wall carbon nanotube.The last one deals with the mechanical behaviour of closed fluid lipid bilayer membranes (vesicles) adhering onto a fiat homogeneous rigid substrate subjected to micro-injection and uniform hydrostatic pressure.
A geometric graph model of the coevolution between citations and coauthorships in scientific papers
Xie, Zheng; Li, Jianping; Li, Miao; Yi, Dongyun
2016-01-01
Collaborations and citations within scientific research grow simultaneously and interact dynamically. Modelling the coevolution between them helps to study many phenomena that can be approached only through combining citation and coauthorship data. A geometric graph for the coevolution is proposed, the mechanism of which synthetically expresses the interactive impacts of authors and papers in a geometrical way. The model is validated against a data set of papers published in PNAS during 2000-2015. The validation shows the ability to reproduce a range of features observed with citation and coauthorship data combined and separately. Particulary, in the empirical distribution of citations per author there exist two limits, in which the distribution appears as a generalized Poisson and a power-law respectively. Our model successfully reproduces the shape of the distribution, and provides an explanation for how the shape emerges. The model also captures the empirically positive correlations between the numbers of ...
Mengle, Vinod G. (Inventor); Thomas, Russell H. (Inventor)
2012-01-01
Nozzle exit configurations and associated systems and methods are disclosed. An aircraft system in accordance with one embodiment includes a jet engine exhaust nozzle having an internal flow surface and an exit aperture, with the exit aperture having a perimeter that includes multiple projections extending in an aft direction. Aft portions of individual neighboring projections are spaced apart from each other by a gap, and a geometric feature of the multiple can change in a monotonic manner along at least a portion of the perimeter. Projections near a support pylon and/or associated heat shield can have particular configurations, including greater flow immersion than other projections.
Galindo-Israel, V.; Imbriale, W.; Shogen, K.; Mittra, R.
1990-01-01
In obtaining solutions to the first-order nonlinear partial differential equations (PDEs) for synthesizing offset dual-shaped reflectors, it is found that previously observed computational problems can be avoided if the integration of the PDEs is started from an inner projected perimeter and integrated outward rather than starting from an outer projected perimeter and integrating inward. This procedure, however, introduces a new parameter, the main reflector inner perimeter radius p(o), when given a subreflector inner angle 0(o). Furthermore, a desired outer projected perimeter (e.g., a circle) is no longer guaranteed. Stability of the integration is maintained if some of the initial parameters are determined first from an approximate solution to the PDEs. A one-, two-, or three-parameter optimization algorithm can then be used to obtain a best set of parameters yielding a close fit to the desired projected outer rim. Good low cross-polarization mapping functions are also obtained. These methods are illustrated by synthesis of a high-gain offset-shaped Cassegrainian antenna and a low-noise offset-shaped Gregorian antenna.
He, W B; Cao, X G; Cai, X Z; Zhang, G Q
2014-01-01
It is studied how the $\\alpha$ cluster degrees of freedom, such as $\\alpha$ clustering configurations close to the $\\alpha$ decay threshold in $^{12}$C and $^{16}$O, including the linear chain, triangle, square, kite, and tetrahedron, affect nuclear collective vibrations with a microscopic dynamical approach, which can describe properties of nuclear ground states well across the nuclide chart and reproduce the standard giant dipole resonance (GDR) of $^{16}$O quite nicely. It is found that the GDR spectrum is highly fragmented into several apparent peaks due to the $\\alpha$ structure. The different $\\alpha$ cluster configurations in $^{12}$C and $^{16}$O have corresponding characteristic spectra of GDR. The number and centroid energies of peaks in the GDR spectra can be reasonably explained by the geometrical and dynamical symmetries of $\\alpha$ clustering configurations. Therefore, the GDR can be regarded as a very effective probe to diagnose the different $\\alpha$ cluster configurations in light nuclei.
Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces
Kamali, Seyedeh Mahsa; Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei
2016-05-01
Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify near-infrared (λ=915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices.
Brezillon, J.; Dwight, R.P.
2009-01-01
Within the next few years, numerical shape optimization based on high fidelity methods is likely to play a strategic role in future aircraft design. In this context, suitable tools have to be developed for solving aerodynamic shape optimization problems, and the adjoint approach - which allows fast and accurate evaluations of the gradients with respect to the design parameters - is seen as a promising strategy. After describing the theory of the viscous discrete adjoint method and its impleme...
Geometrical Bioelectrodynamics
Ivancevic, Vladimir G
2008-01-01
This paper proposes rigorous geometrical treatment of bioelectrodynamics, underpinning two fast-growing biomedical research fields: bioelectromagnetism, which deals with the ability of life to produce its own electromagnetism, and bioelectromagnetics, which deals with the effect on life from external electromagnetism. Keywords: Bioelectrodynamics, exterior geometrical machinery, Dirac-Feynman quantum electrodynamics, functional electrical stimulation
Stalactite Growth as a Free-Boundary Problem: A Geometric Law and Its Platonic Ideal
Short, Martin B.; Baygents, James C.; Beck, J. Warren; Stone, David A.; Toomey, Rickard S.; Goldstein, Raymond E.
2005-01-01
The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we consider the interplay of thin-film fluid dynamics, calcium carbonate chemistry, and CO2 transport in the cave to show that stalactites evolve according to a novel local geometric growth law which exhibits extreme amplification at the tip as a consequence of the locally-varying fluid layer thickness. Studies of this model show that a broad class of initial conditions is attracted to an ideal shape which is strikingly close to a statistical average of natural stalactites.
SAP ERP financial accounting and controlling configuration and use management
Okungbowa, Andrew
2015-01-01
SAP ERP modules are notoriously hard to configure and use effectively without a lot of practice and experience. But as SAP ERP Financial Accounting and Controlling: Configuration and Use Management shows, it doesn't have to be so difficult. The book takes a systematic approach that leads SAP Financial Accounting and Controlling (FICO) users step by step through configuring and using all the program's facets. This approach makes configuration complexities manageable. The book's author-SAP expert, trainer, and accountant Andrew Okun
Geometric Hyperplanes: Desargues Encodes Doily
Saniga, Metod
2011-01-01
It is shown that the structure of the generalized quadrangle of order two is fully encoded in the properties of the Desargues configuration. A point of the quadrangle is represented by a geometric hyperplane of the Desargues configuration and its line by a set of three hyperplanes such that one of them is the complement of the symmetric difference of the remaining two and they all share a pair of non-collinear points.
ATLAS software configuration and build tool optimisation
Rybkin, Grigory; Atlas Collaboration
2014-06-01
ATLAS software code base is over 6 million lines organised in about 2000 packages. It makes use of some 100 external software packages, is developed by more than 400 developers and used by more than 2500 physicists from over 200 universities and laboratories in 6 continents. To meet the challenge of configuration and building of this software, the Configuration Management Tool (CMT) is used. CMT expects each package to describe its build targets, build and environment setup parameters, dependencies on other packages in a text file called requirements, and each project (group of packages) to describe its policies and dependencies on other projects in a text project file. Based on the effective set of configuration parameters read from the requirements files of dependent packages and project files, CMT commands build the packages, generate the environment for their use, or query the packages. The main focus was on build time performance that was optimised within several approaches: reduction of the number of reads of requirements files that are now read once per package by a CMT build command that generates cached requirements files for subsequent CMT build commands; introduction of more fine-grained build parallelism at package task level, i.e., dependent applications and libraries are compiled in parallel; code optimisation of CMT commands used for build; introduction of package level build parallelism, i. e., parallelise the build of independent packages. By default, CMT launches NUMBER-OF-PROCESSORS build commands in parallel. The other focus was on CMT commands optimisation in general that made them approximately 2 times faster. CMT can generate a cached requirements file for the environment setup command, which is especially useful for deployment on distributed file systems like AFS or CERN VMFS. The use of parallelism, caching and code optimisation significantly-by several times-reduced software build time, environment setup time, increased the efficiency of
Modeling and Development of RMD Configuration Magnetic Bearing
Directory of Open Access Journals (Sweden)
K.P. Lijesh
2015-06-01
Full Text Available The low load carrying capacity of Passive Magnetic Bearings (PMBs has restricted their use in many industrial applications. The Rotation Magnetized Direction (RMD configuration has emerged as a strong and viable method that is able to substantially enhance the load carrying capacity of passive magnetic bearings. It consists of both radially and axially polarized passive magnets. But the physical realization of a radially polarized magnet is difficult to achieve. In the present work, a RMD structure consisting of aluminum ring and cubical shaped magnets is proposed by developing the radially polarized magnets required for RMD structure. A theoretical model is derived by simulating the cuboid magnets in form of sector magnets by developing equivalent surface area. An experimental setup was designed and developed to conduct experimental verification. The theoretical model is validated by conducting experiments on RMD configuration magnetic bearing and axially magnetized full ring bearing. The comparison of the load carrying capacity by different configuration is performed and results are presented.
Salzman, Oren; Halperin, Dan
2012-01-01
We extend our study of Motion Planning via Manifold Samples (MMS), a general algorithmic framework that combines geometric methods for the exact and complete analysis of low-dimensional configuration spaces with sampling-based approaches that are appropriate for higher dimensions. The framework explores the configuration space by taking samples that are entire low-dimensional manifolds of the configuration space capturing its connectivity much better than isolated point samples. The contributions of this paper are as follows: (i) We present a recursive application of MMS in a six-dimensional configuration space, enabling the coordination of two polygonal robots translating and rotating amidst polygonal obstacles. In the adduced experiments for the more demanding test cases MMS clearly outperforms PRM, with over 20-fold speedup in a coordination-tight setting. (ii) A probabilistic completeness proof for the most prevalent case, namely MMS with samples that are affine subspaces. (iii) A closer examination of th...
Field line mapping and equilibrium reconstructions in new CNT Configuration
Traverso, Peter; Pedersen, Thomas; Brenner, Paul; Sarasola, Xabier; Durand de Gevigney, Benoit
2010-11-01
The Columbia Non-neutral Torus (CNT) has the useful feature of having adjustable coil geometry, creating up to three different stellarators each having a completely new shape to its magnetic surfaces and a different Iota profile. Recently the tilt angle between the two interlocking coils has been changed for the first time on CNT, allowing a study of the new magnetic geometry. In the new configuration field line mapping has been accomplished for multiple current ratios and magnetic fields to confirm the existence of good nested magnetic surfaces. At a specific current ratio a large one-three island chain is created. Plasma parameters have been measured with the new coil configuration, both in cases of a large internal island chain, and in cases without. Full 3D equilibrium reconstructions of potential and density are being performed using a modified version of the existing Poisson-Boltzmann solver. Field line mapping in this configuration will be presented, and a progress report on the equilibrium reconstructions will also be given.
Best of Both Worlds: Uniform sampling in Cartesian and Cayley Molecular Assembly Configuration Space
Ozkan, Aysegul
2014-01-01
EASAL (efficient atlasing and sampling of assembly landscapes) is a recently reported geometric method for representing, visualizing, sampling and computing integrals over the potential energy landscape tailored for small molecular assemblies. EASAL's efficiency arises from the fact that small assembly landscapes permit the use of so-called Cayley parameters (inter-atomic distances) for geometric representation and sampling of the assembly configuration space regions; this results in their isolation, convexification, customized sampling and systematic traversal using a comprehensive topological roadmap, ensuring reasonable coverage of crucial but narrow regions of low effective dimension. However, this alone is inadequate for accurate computation of configurational entropy and other integrals, required for estimation of both free energy and kinetics - where it is essential to obtain uniform sampling in appropriate cartesian or moduli space parameterization. Standard adjustment of Cayley sampling via the Jacob...
Landsat 8 thermal infrared sensor geometric characterization and calibration
Storey, James C.; Choate, Michael J.; Moe, Donald
2014-01-01
The Landsat 8 spacecraft was launched on 11 February 2013 carrying two imaging payloads: the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). The TIRS instrument employs a refractive telescope design that is opaque to visible wavelengths making prelaunch geometric characterization challenging. TIRS geometric calibration thus relied heavily on on-orbit measurements. Since the two Landsat 8 payloads are complementary and generate combined Level 1 data products, the TIRS geometric performance requirements emphasize the co-alignment of the OLI and TIRS instrument fields of view and the registration of the OLI reflective bands to the TIRS long-wave infrared emissive bands. The TIRS on-orbit calibration procedures include measuring the TIRS-to-OLI alignment, refining the alignment of the three TIRS sensor chips, and ensuring the alignment of the two TIRS spectral bands. The two key TIRS performance metrics are the OLI reflective to TIRS emissive band registration accuracy, and the registration accuracy between the TIRS thermal bands. The on-orbit calibration campaign conducted during the commissioning period provided an accurate TIRS geometric model that enabled TIRS Level 1 data to meet all geometric accuracy requirements. Seasonal variations in TIRS-to-OLI alignment have led to several small calibration parameter adjustments since commissioning.
A Geometric Algebra Perspective On Quantum Computational Gates And Universality In Quantum Computing
Cafaro, Carlo
2010-01-01
We investigate the utility of geometric (Clifford) algebras (GA) methods in two specific applications to quantum information science. First, using the multiparticle spacetime algebra (MSTA, the geometric algebra of a relativistic configuration space), we present an explicit algebraic description of one and two-qubit quantum states together with a MSTA characterization of one and two-qubit quantum computational gates. Second, using the above mentioned characterization and the GA description of the Lie algebras SO(3) and SU(2) based on the rotor group Spin+(3, 0) formalism, we reexamine Boykin's proof of universality of quantum gates. We conclude that the MSTA approach does lead to a useful conceptual unification where the complex qubit space and the complex space of unitary operators acting on them become united, with both being made just by multivectors in real space. Finally, the GA approach to rotations based on the rotor group does bring conceptual and computational advantages compared to standard vectoria...
Geometric optimal design of MR damper considering damping force, control energy and time constant
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Q H; Choi, S B [Smart Structures and Systems Laboratory, Department of Mechanical Engineering, INHA University, Incheon 402-751 (Korea, Republic of); Kim, K S [Department of Mechanical and Automotive Engineering, Kongju National University, Chonan 330-240 (Korea, Republic of)], E-mail: seungbok@inha.ac.kr
2009-02-01
This paper presents an optimal design of magnetorheological (MR) damper based on finite element analysis. The MR damper is constrained in a specific volume and the optimization problem identifies geometric dimensions of the damper that minimizes an objective function. The objective function is proposed by considering the damping force, dynamic range and the inductive time constant of the damper. After describing the configuration of the MR damper, a quasi-static modelling of the damper is performed based on Bingham model of MR fluid. The initial geometric dimensions of the damper are then determined based on the assumption of constant magnetic flux density throughout the magnetic circuit of the damper. Subsequently, the optimal design variables that minimize the objective function are determined using a golden-section algorithm and a local quadratic fitting technique via commercial finite element method parametric design language. A comparative work on damping force and time constant between the initial and optimal design is undertaken.
Shape memory polymer network with thermally distinct elasticity and plasticity.
Zhao, Qian; Zou, Weike; Luo, Yingwu; Xie, Tao
2016-01-01
Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices.
Metastable states of hydrogen: their geometric phases and flux densities
Gasenzer, T; Trappe, M -I
2011-01-01
We discuss the geometric phases and flux densities for the metastable states of hydrogen with principal quantum number n=2 being subjected to adiabatically varying external electric and magnetic fields. Convenient representations of the flux densities as complex integrals are derived. Both, parity conserving (PC) and parity violating (PV) flux densities and phases are identified. General expressions for the flux densities following from rotational invariance are derived. Specific cases of external fields are discussed. In a pure magnetic field the phases are given by the geometry of the path in magnetic field space. But for electric fields in presence of a constant magnetic field and for electric plus magnetic fields the geometric phases carry information on the atomic parameters, in particular, on the PV atomic interaction. We show that for our metastable states also the decay rates can be influenced by the geometric phases and we give a concrete example for this effect. Finally we emphasise that the general...
On Optimal Shapes in Materials and Structures
DEFF Research Database (Denmark)
Pedersen, Pauli
2000-01-01
In the micromechanics design of materials, as well as in the design of structural connections, the boundary shape plays an important role. The objective may be the stiffest design, the strongest design or just a design of uniform energy density along the shape. In an energy formulation it is proven...... that these three objectives have the same solution, at least within the limits of geometrical constraints, including the parametrization. Without involving stress/strain fields, the proof holds for 3D-problems, for power-law nonlinear elasticity and for anisotropic elasticity. To clarify the importance...... of parametrization, the problem of material/hole design for maximum bulk modulus is analysed. A simple optimality criterion is derived and with a simple superelliptic parametrization, agreement with Hashin-Shtrikman bounds are found. More general examples including nonequal principal strains, nonlinear elasticity...
Shape and topology optimization of enzymatic microreactors
DEFF Research Database (Denmark)
Pereira Rosinha, Ines
configuration. In this thesis structural optimization methods were exclusively applied to enzymatic microreactors. The case studies were chosen such that they can be experimentally tested afterwards. In this way, the design of the reactor is customized to the reaction system and itcontributes to the reduction......Structural optimization methods have been used by mechanical and civil engineers over the yearsto find the optimal structures. Structural optimization is a series of computational techniqueswhich include shape and topology optimization. Shape optimization is directly applied to theboundaries...... in a chemical process do not always yield in the best reaction conditions.This thesis develops an innovative application of topology and shape optimization methods to achemical engineering problem. The main goal is to design a reactor according to the limitations of the reaction system by modifying the reactor...
Primary structure and configuration of tea polysaccharide
Institute of Scientific and Technical Information of China (English)
ZHOU Peng; XIE Mingyong; NIE Shaoping; WANG Xiaoru
2004-01-01
The monosaccharide composition of a tea polysaccharide(TGC)was determined by GC-MS method.Furthermore,the primary structure of tea polysaccharide and its configuration in the aqueous solution were investigated utilizing a combination of classical chemical methods and modern instrumental techniques including GC-MS,Proton NMR,UV and CD.The results indicate that TGC consists of 6 monosaccharides: Rha,Ara,Xyl,Glu,Man and Gal.The configuration of TGC in water solution is proposed to be an ordered helix.The possible primary structure of TGC was outlined as below: the basic structure of the main chain consists of Rha,Glu and Gal units.All three monosaccharides can potentially be connected to branch chains consisting of mainly Ara,and the linkages could be in β1 →2,β1 →3,β2→3 forms.When branch chain is absent in the basic structure of the main chain the linkage consists of only β1→3; Xyl exists at the terminal end of either the main chain or the branch chain with β1 → linkage.
Numerical and experimental investigation of geometric parameters in projection welding
DEFF Research Database (Denmark)
Kristensen, Lars; Zhang, Wenqi; Bay, Niels
2000-01-01
Resistance projection welding is widely used for joining of workpieces with almost any geometric combination. This makes standardization of projection welding impossible. In order to facilitate industrial applications of projection welding, systematic investigations are carried out on the geometric...... parameters by numerical modeling and experimental studies. SORPAS, an FEM program for numerical modeling of resistance welding, is developed as a tool to help in the phase of product design and process optimization in both spot and projection welding. A systematic experimental investigation of projection...... welding a disc to a ring with a triangular ring projection has been carried out to study the influence of the geometric parameters in various metal combinations. In these studies, SORPAS has been used as a supporting tool to understand the relationship of the parameters and the phenomena occurring...
Mechanical and geometric advantages in compliant mechanism optimization
Institute of Scientific and Technical Information of China (English)
Michael Yu WANG
2009-01-01
This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formula-tions of compliant mechanisms posed as a topology optimization problem. With a linear elastic structuralanalysis, we quantify mechanical (and geometric) advan-tage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formula-tions.
Emergent Newtonian dynamics and the geometric origin of mass
Energy Technology Data Exchange (ETDEWEB)
D’Alessio, Luca, E-mail: dalessio@bu.edu [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Physics Department, Boston University, Boston, MA 02215 (United States); Polkovnikov, Anatoli, E-mail: asp@bu.edu [Physics Department, Boston University, Boston, MA 02215 (United States)
2014-06-15
We consider a set of macroscopic (classical) degrees of freedom coupled to an arbitrary many-particle Hamiltonian system, quantum or classical. These degrees of freedom can represent positions of objects in space, their angles, shape distortions, magnetization, currents and so on. Expanding their dynamics near the adiabatic limit we find the emergent Newton’s second law (force is equal to the mass times acceleration) with an extra dissipative term. In systems with broken time reversal symmetry there is an additional Coriolis type force proportional to the Berry curvature. We give the microscopic definition of the mass tensor. The mass tensor is related to the non-equal time correlation functions in equilibrium and describes the dressing of the slow degree of freedom by virtual excitations in the system. In the classical (high-temperature) limit the mass tensor is given by the product of the inverse temperature and the Fubini–Study metric tensor determining the natural distance between the eigenstates of the Hamiltonian. For free particles this result reduces to the conventional definition of mass. This finding shows that any mass, at least in the classical limit, emerges from the distortions of the Hilbert space highlighting deep connections between any motion (not necessarily in space) and geometry. We illustrate our findings with four simple examples. -- Highlights: •Derive the macroscopic Newton’s equation from the microscopic many-particle Schrödinger’s equation. •Deep connection between geometry and dynamics. •Geometrical interpretation of the mass of macroscopic object as deformation of Hilbert space. •Microscopic expression for mass and friction tensors.
Liu, Yi; Dai, Feng; Fan, Pengxian; Xu, Nuwen; Dong, Lu
2017-06-01
Intermittent joints in rock mass are quite sensitive to cyclic loading conditions. Understanding the fatigue mechanical properties of jointed rocks is beneficial for rational design and stability analysis of rock engineering projects. This study experimentally investigated the influences of joint geometry (i.e., dip angle, persistency, density and spacing) on the fatigue mechanism of synthetic jointed rock models. Our results revealed that the stress-strain curve of jointed rock under cyclic loadings is dominated by its curve under monotonic uniaxial loadings; the terminal strain in fatigue curve is equal to the post-peak strain corresponding to the maximum cyclic stress in the monotonic stress-strain curve. The four joint geometrical parameters studied significantly affect the fatigue properties of jointed rocks, including the irreversible strains, the fatigue deformation modulus, the energy evolution, the damage variable and the crack coalescence patterns. The higher the values of the geometrical parameters, the lower the elastic energy stores in this jointed rock, the higher the fatigue damage accumulates in the first few cycles, and the lower the fatigue life. The elastic energy has certain storage limitation, at which the fatigue failure occurs. Two basic micro-cracks, i.e., tensile wing crack and shear crack, are observed in cyclic loading and unloading tests, which are controlled principally by joint dip angle and persistency. In general, shear cracks only occur in the jointed rock with higher dip angle or higher persistency, and the jointed rock is characterized by lower fatigue strength, larger damage variable and lower fatigue life.
Geometric registration and rectification of spaceborne SAR imagery
Curlander, J. C.; Pang, S. N.
1982-01-01
This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.
Hadronic and elementary multiplicity distributions in a geometrical approach
Valin, P; Menon, M J
2000-01-01
We construct the hadronic multiplicity distribution in terms of an elementary distribution (at given impact parameter) and the inelastic overlap function characterized by the observed BEL (Blacker-Edgier-Larger) behaviour. With suitable parametrizations for the elementary quantities, based on some geometrical arguments and the most recent data on e+e- annihilation, an excellent description of pp and p(bar)p inelastic multiplicity distributions at the highest energies is obtained. With this approach, we quantitatively correlate the violations of scalings in multiplicity distributions (Koba-Nielsen-Olesen) and elastic scattering (Geometrical) at high energies.
Evolution of Brain Tumor and Stability of Geometric Invariants
Directory of Open Access Journals (Sweden)
K. Tawbe
2008-01-01
Full Text Available This paper presents a method to reconstruct and to calculate geometric invariants on brain tumors. The geometric invariants considered in the paper are the volume, the area, the discrete Gauss curvature, and the discrete mean curvature. The volume of a tumor is an important aspect that helps doctors to make a medical diagnosis. And as doctors seek a stable calculation, we propose to prove the stability of some invariants. Finally, we study the evolution of brain tumor as a function of time in two or three years depending on patients with MR images every three or six months.
Non-geometric fluxes and non-associative geometry
Plauschinn, Erik
2012-01-01
In these proceedings, we discuss non-commutativity in closed string theory. In analogy to the open-string sector, for closed strings we first motivate a cyclic double commutator to be evaluated for backgrounds with geometric or non-geometric fluxes. A non-trivial result for such an expression indicates a non-associative structure. Second, we define a conformal field theory at linear order in background fluxes and compute correlation functions therein. From these we motivate a tri-product which captures non-commutative and non-associative effects.
Computing the Expected Value and Variance of Geometric Measures
DEFF Research Database (Denmark)
Staals, Frank; Tsirogiannis, Constantinos
2017-01-01
points in P. This problem is a crucial part of modern ecological analyses; each point in P represents a species in d-dimensional trait space, and the goal is to compute the statistics of a geometric measure on this trait space, when subsets of species are selected under random processes. We present...... efficient exact algorithms for computing the mean and variance of several geometric measures when point sets are selected under one of the described random distributions. More specifically, we provide algorithms for the following measures: the bounding box volume, the convex hull volume, the mean pairwise...
Geometric phase gradient and spin Hall effect of light
Ling, Xiaohui; Zhou, Xinxing; Qiu, Cheng-Wei
2016-10-01
The spin Hall effect (SHE) of light originates from the spin-orbit interaction, which can be explained in terms of two geometric phases: the Rytov-Vladimirskii-Berry phase and the Pancharatnam-Berry phase. Here we present a unified theoretical description of the SHE based on the two types of geometric phase gradients, and observe experimentally the SHE in structured dielectric metasurfaces induced by the PB phase. Unlike the weak real-space spin-Hall shift induced by the SRB phase occurring at interfacial reflection/refraction, the observed SHE occurs in momentum space is large enough to be measured directly.
Millimeter-wave antennas configurations and applications
du Preez, Jaco
2016-01-01
This book comprehensively reviews the state of the art in millimeter-wave antennas, traces important recent developments and provides information on a wide range of antenna configurations and applications. While fundamental theoretical aspects are discussed whenever necessary, the book primarily focuses on design principles and concepts, manufacture, measurement techniques, and practical results. Each of the various antenna types scalable to millimeter-wave dimensions is considered individually, with coverage of leaky-wave and surface-wave antennas, printed antennas, integrated antennas, and reflector and lens systems. The final two chapters address the subject from a systems perspective, providing an overview of supporting circuitry and examining in detail diverse millimeter-wave applications, including high-speed wireless communications, radio astronomy, and radar. The vast amount of information now available on millimeter-wave systems can be daunting for researchers and designers entering the field. This b...
Schulte, Mathis; Ostroff, Cheri; Shmulyian, Svetlana; Kinicki, Angelo
2009-05-01
Research on organizational climate has tended to focus on independent dimensions of climate rather than studying the total social context as configurations of multiple climate dimensions. The authors examined relationships between configurations of unit-level climate dimensions and organizational outcomes. Three profile characteristics represented climate configurations: (1) elevation, or the mean score across climate dimensions; (2) variability, or the extent to which scores across dimensions vary; and (3) shape, or the pattern of the dimensions. Across 2 studies (1,120 employees in 120 bank branches and 4,317 employees in 86 food distribution stores), results indicated that elevation was related to collective employee attitudes and service perceptions, while shape was related to customer satisfaction and financial performance. With respect to profile variability, results were mixed. The discussion focuses on future directions for taking a configural approach to organizational climate.
Subsets of configurations and canonical partition functions
DEFF Research Database (Denmark)
Bloch, J.; Bruckmann, F.; Kieburg, M.;
2013-01-01
We explain the physical nature of the subset solution to the sign problem in chiral random matrix theory: the subset sum over configurations is shown to project out the canonical determinant with zero quark charge from a given configuration. As the grand canonical chiral random matrix partition...
Description of shape characteristics through Fourier and wavelet analysis
Directory of Open Access Journals (Sweden)
Yuan Zhanwei
2014-02-01
Full Text Available In this paper, Fourier and Wavelet transformation were adopted to analyze shape characteristics, with twelve simple shapes and two types of second phases from real microstructure morphology. According to the results of Fast Fourier transformation (FFT, the Fourier descriptors can be used to characterize the shape from the aspects of the first eight Normalization amplitudes, the number of the largest amplitudes to inverse reconstruction, similarity of shapes and profile roughness. And the Diepenbroek Roughness was rewritten by Normalization amplitudes of FFT results. Moreover, Sum Square of Relative Errors (SSRE of Wavelet transformation (WT signal sequence, including approximation signals and detail signals, was introduced to evaluate the similarity and relative orientation among shapes. As a complement to FFT results, the WT results can retain more detailed information of shapes including their orientations. Besides, the geometric signatures of the second phases were extracted by image processing and then were analyzed by means of FFT and WT.
Description of shape characteristics through Fourier and wavelet analysis
Institute of Scientific and Technical Information of China (English)
Yuan Zhanwei; Li Fuguo; Zhang Peng; Chen Bo
2014-01-01
In this paper, Fourier and Wavelet transformation were adopted to analyze shape char-acteristics, with twelve simple shapes and two types of second phases from real microstructure mor-phology. According to the results of Fast Fourier transformation (FFT), the Fourier descriptors can be used to characterize the shape from the aspects of the first eight Normalization amplitudes, the number of the largest amplitudes to inverse reconstruction, similarity of shapes and profile roughness. And the Diepenbroek Roughness was rewritten by Normalization amplitudes of FFT results. Moreover, Sum Square of Relative Errors (SSRE) of Wavelet transformation (WT) signal sequence, including approximation signals and detail signals, was introduced to evaluate the simi-larity and relative orientation among shapes. As a complement to FFT results, the WT results can retain more detailed information of shapes including their orientations. Besides, the geometric sig-natures of the second phases were extracted by image processing and then were analyzed by means of FFT and WT.
DEFF Research Database (Denmark)
Achiche, Sofiane; Ahmed, Saeema
2009-01-01
with a different set of geometric features and shapes. In this paper the authors propose an automatic approach to formalize the relationships between geometric information of 3D objects and the intended emotion using fuzzy logic. In addition automatically generated fuzzy rules and sets are developed and compared...
Laser beam shaping theory and techniques, second edition
Dickey, Fred M
2014-01-01
Laser Beam Shaping: Theory and Techniques addresses the theory and practice of every important technique for lossless beam shaping. Complete with experimental results as well as guidance on when beam shaping is practical and when each technique is appropriate, the Second Edition is updated to reflect significant developments in the field. This authoritative text:Features new chapters on axicon light ring generation systems, laser-beam-splitting (fan-out) gratings, vortex beams, and microlens diffusersDescribes the latest advances in beam profile measurement technology and laser beam shaping using diffractive diffusersContains new material on wavelength dependence, channel integrators, geometrical optics, and optical softwareLaser Beam Shaping: Theory and Techniques, Second Edition not only provides a working understanding of the fundamentals, but also offers insight into the potential application of laser-beam-profile shaping in laser system design.
SIAM Conference on Geometric Design and Computing. Final Technical Report
Energy Technology Data Exchange (ETDEWEB)
None
2002-03-11
The SIAM Conference on Geometric Design and Computing attracted 164 domestic and international researchers, from academia, industry, and government. It provided a stimulating forum in which to learn about the latest developments, to discuss exciting new research directions, and to forge stronger ties between theory and applications. Final Report
Geometric and Algebraic Approaches in the Concept of Complex Numbers
Panaoura, A.; Elia, I.; Gagatsis, A.; Giatilis, G.-P.
2006-01-01
This study explores pupils' performance and processes in tasks involving equations and inequalities of complex numbers requiring conversions from a geometric representation to an algebraic representation and conversions in the reverse direction, and also in complex numbers problem solving. Data were collected from 95 pupils of the final grade from…
Space-time-matter analytic and geometric structures
Brüning, Jochen
2017-01-01
At the boundary of mathematics and mathematical physics, this monograph explores recent advances in the mathematical foundations of string theory and cosmology. The geometry of matter and the evolution of geometric structures as well as special solutions, singularities and stability properties of the underlying partial differential equations are discussed.
Developments and retrospectives in Lie theory geometric and analytic methods
Penkov, Ivan; Wolf, Joseph
2014-01-01
This volume reviews and updates a prominent series of workshops in representation/Lie theory, and reflects the widespread influence of those workshops in such areas as harmonic analysis, representation theory, differential geometry, algebraic geometry, and mathematical physics. Many of the contributors have had leading roles in both the classical and modern developments of Lie theory and its applications. This Work, entitled Developments and Retrospectives in Lie Theory, and comprising 26 articles, is organized in two volumes: Algebraic Methods and Geometric and Analytic Methods. This is the Geometric and Analytic Methods volume. The Lie Theory Workshop series, founded by Joe Wolf and Ivan Penkov and joined shortly thereafter by Geoff Mason, has been running for over two decades. Travel to the workshops has usually been supported by the NSF, and local universities have provided hospitality. The workshop talks have been seminal in describing new perspectives in the field covering broad areas of current re...
Central configurations, periodic orbits, and Hamiltonian systems
Llibre, Jaume; Simó, Carles
2015-01-01
The notes of this book originate from three series of lectures given at the Centre de Recerca Matemàtica (CRM) in Barcelona. The first one is dedicated to the study of periodic solutions of autonomous differential systems in Rn via the Averaging Theory and was delivered by Jaume Llibre. The second one, given by Richard Moeckel, focusses on methods for studying Central Configurations. The last one, by Carles Simó, describes the main mechanisms leading to a fairly global description of the dynamics in conservative systems. The book is directed towards graduate students and researchers interested in dynamical systems, in particular in the conservative case, and aims at facilitating the understanding of dynamics of specific models. The results presented and the tools introduced in this book include a large range of applications.
Directory of Open Access Journals (Sweden)
Christian Obermair
2011-11-01
Full Text Available We study the crossover of quantum point contacts from (i individual-atom contacts to (ii electronic-shell effects and finally to (iii geometric-shell effects in electrochemically deposited silver contacts. The method allows the fabrication of mechanically unstrained structures, which is a requirement for determining the individual atomic configuration by means of a detailed lifetime analysis of their conductance. Within the geometric-shell model, the sequence of conductance maxima is explained quantitatively based on the crystal structure data of silver, and the growth mechanism of the nanowires is discussed.
Tian, Gui Yun; Gao, Yunlai; Li, Kongjing; Wang, Yizhe; Gao, Bin; He, Yunze
2016-06-08
This paper reviews recent developments of eddy current pulsed thermography (ECPT) for material characterization and nondestructive evaluation (NDE). Due to the fact that line-coil-based ECPT, with the limitation of non-uniform heating and a restricted view, is not suitable for complex geometry structures evaluation, Helmholtz coils and ferrite-yoke-based excitation configurations of ECPT are proposed and compared. Simulations and experiments of new ECPT configurations considering the multi-physical-phenomenon of hysteresis losses, stray losses, and eddy current heating in conjunction with uniform induction magnetic field have been conducted and implemented for ferromagnetic and non-ferromagnetic materials. These configurations of ECPT for metallic material and defect characterization are discussed and compared with conventional line-coil configuration. The results indicate that the proposed ECPT excitation configurations can be applied for different shapes of samples such as turbine blade edges and rail tracks.
Directory of Open Access Journals (Sweden)
Gui Yun Tian
2016-06-01
Full Text Available This paper reviews recent developments of eddy current pulsed thermography (ECPT for material characterization and nondestructive evaluation (NDE. Due to the fact that line-coil-based ECPT, with the limitation of non-uniform heating and a restricted view, is not suitable for complex geometry structures evaluation, Helmholtz coils and ferrite-yoke-based excitation configurations of ECPT are proposed and compared. Simulations and experiments of new ECPT configurations considering the multi-physical-phenomenon of hysteresis losses, stray losses, and eddy current heating in conjunction with uniform induction magnetic field have been conducted and implemented for ferromagnetic and non-ferromagnetic materials. These configurations of ECPT for metallic material and defect characterization are discussed and compared with conventional line-coil configuration. The results indicate that the proposed ECPT excitation configurations can be applied for different shapes of samples such as turbine blade edges and rail tracks.
Non-geometric fluxes and mixed-symmetry potentials
Bergshoeff, E.A.; Penas, V.A.; Riccioni, F.; Risoli, S.
2015-01-01
We discuss the relation between generalised fluxes and mixed-symmetry potentials. We refer to the fluxes that cannot be described even locally in the framework of supergravity as ‘non-geometric’. We first consider the NS fluxes, and point out that the non-geometric R flux is dual to a mixed-symmetry
Object recognition with stereo vision and geometric hashing
Dijck, van Harry; Heijden, van der Ferdinand
2003-01-01
In this paper we demonstrate a method to recognize 3D objects and to estimate their pose. For that purpose we use a combination of stereo vision and geometric hashing. Stereo vision is used to generate a large number of 3D low level features, of which many are spurious because at that stage of the p
Object recognition with stereo vision and geometric hashing
van Dijck, H.A.L.; van der Heijden, Ferdinand
In this paper we demonstrate a method to recognize 3D objects and to estimate their pose. For that purpose we use a combination of stereo vision and geometric hashing. Stereo vision is used to generate a large number of 3D low level features, of which many are spurious because at that stage of the
Geometric Dimensioning and Tolerancing. Drafting Module 9. Instructor's Guide.
Missouri Univ., Columbia. Instructional Materials Lab.
This Missouri Vocational Instruction Management System instructor's drafting guide has been keyed to the drafting competency profile developed by state industry and education professionals. The guide contains a cross-reference table of instructional materials. This unit covers geometric dimensioning and tolerancing. The unit contains the…
Absolute instruments and perfect imaging in geometrical optics
Tyc, Tomas; Sarbort, Martin; Bering, Klaus
2011-01-01
We investigate imaging by spherically symmetric absolute instruments that provide perfect imaging in the sense of geometrical optics. We derive a number of properties of such devices, present a general method for designing them and use this method to propose several new absolute instruments, in particular a lens providing a stigmatic image of an optically homogeneous region and having a moderate refractive index range.
Material inhomogeneities and their evolution a geometric approach
Epstein, Marcelo
2007-01-01
Presents a unified treatment of the inhomogeneity theory using some of the tools of modern differential geometry. This book deals with the geometrical description of uniform bodies and their homogeneity conditions. It also develops a theory of material evolution and discusses its relevance in various applied contexts.
Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube
Directory of Open Access Journals (Sweden)
JB Sosa
2015-10-01
Full Text Available Any hydraulic reaction turbine is installed with a draft tube that impacts widely the entire turbine performance, on which its functions are as follows: drive the flux in appropriate manner after it releases its energy to the runner; recover the suction head by a suction effect; and improve the dynamic energy in the runner outlet. All these functions are strongly linked to the geometric definition of the draft tube. This article proposes a geometric parametrization and analysis of a Francis turbine draft tube. Based on the parametric definition, geometric changes in the draft tube are proposed and the turbine performance is modeled by computational fluid dynamics; the boundary conditions are set by measurements performed in a hydroelectric power plant. This modeling allows us to see the influence of the draft tube shape on the entire turbine performance. The numerical analysis is based on the steady-state solution of the turbine component flows for different guide vanes opening and multiple modified draft tubes. The computational fluid dynamics predictions are validated using hydroelectric plant measurements. The prediction of the turbine performance is successful and it is linked to the draft tube geometric features; therefore, it is possible to obtain a draft tube parameter value that results in a desired turbine performance.
Guo, Kai; Ma, Ying; Li, Huiqiao; Zhai, Tianyou
2016-02-24
Wire-shaped flexible supercapacitors (SCs) have aroused much attention due to their small size, light weight, high flexibility, and deformability. However, the previously reported wire-shaped SCs usually involve complex assembly processes, encounter potential structural instabilities, and the influence of dynamic bending on the electrochemical stability of wire-shaped SCs is also not clear. Here, a parallel double helix wire-shaped supercapacitor (PDWS) protocol has been developed with two symmetric titanium@MnO2 fiber electrodes winded on a flexible nylon fiber by a simple and reliable process. The PDWSs show an operate voltage of 0.8 V, a high capacitance of 15.6 mF cm(-2) and an energy density of 1.4 µWh cm(-2) . Due to rational structure design, the PDWSs demonstrate excellent mechanical and electrochemical stability under both static and dynamic deformations. Over 3500 bending cycles, 88.0% of the initial capacitance can still be retained. In terms of dynamic bending, it is found that the cyclic voltammetry curves show periodically fluctuations simultaneously with the bending frequency and the intensity of fluctuation increases with higher bending frequency, while the dynamic capacitance is almost not affected. With extraordinary mechanical flexibility and excellent electrochemical stability, the high performance PDWS is considered to be a promising power source for wearable electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Riemannian geometric approach to human arm dynamics, movement optimization, and invariance.
Biess, Armin; Flash, Tamar; Liebermann, Dario G
2011-03-01
We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparameterized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm's configuration space may provide insights into the emerging properties of the movements generated by the motor system.
Adapting Configuration Management for Agile Teams Balancing Sustainability and Speed
Moreira, Mario E
2009-01-01
Adapting Configuration Management for Agile Teams provides very tangible approaches on how Configuration Management with its practices and infrastructure can be adapted and managed in order to directly benefit agile teams. Written by Mario E. Moreira, author of Software Configuration Management Implementation Roadmap , columnist for CM Crossroads online community and writer for the Agile Journal, this unique book provides concrete guidance on tailoring CM for Agile projects without sacrificing the principles of Configuration Management.
Geometric phase and its applications to fundamental physics
Capolupo, A
2015-01-01
We report on recent results showing that the geometric phase can be used as a tool in the analysis of many different physical systems, as mixed boson systems, CPT and CP violations, Unruh effects and thermal states. We show that the geometric phases appearing in the time evolution of mixed meson systems like $B_{s}^{0}-\\bar{B}_{s}^{0}$ and the $K^{0}-\\bar{K}^{0}$ are linked to the parameter $z$ describing the $CPT$ violation. A non zero phase difference between particle and antiparticle arises only in the presence of $CPT$ symmetry breaking. Then the geometric phase can represent a completely new test for the $CPT$ invariance. Moreover, we study the geometric phase of systems represented by mixed state and undergoing a nonunitary evolution and propose the realization of interferometers which can prove the existence of the Unruh effect and can allow very precise measurements of temperature. We are glad to dedicate this paper to Professor Gaetano Vilasi in the occasion of his 70th birthday.
Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces
Kamali, Seyedeh Mahsa; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei
2015-01-01
Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point, and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics, or esthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and highly transparent flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept introduces a novel paradigm ...
Total Gaussian curvature, drop shapes and the range of applicability of drop shape techniques.
Saad, Sameh M I; Neumann, A Wilhelm
2014-02-01
Drop shape techniques are used extensively for surface tension measurement. It is well-documented that, as the drop/bubble shape becomes close to spherical, the performance of all drop shape techniques deteriorates. There have been efforts quantifying the range of applicability of drop techniques by studying the deviation of Laplacian drops from the spherical shape. A shape parameter was introduced in the literature and was modified several times to accommodate different drop constellations. However, new problems arise every time a new configuration is considered. Therefore, there is a need for a universal shape parameter applicable to pendant drops, sessile drops, liquid bridges as well as captive bubbles. In this work, the use of the total Gaussian curvature in a unified approach for the shape parameter is introduced for that purpose. The total Gaussian curvature is a dimensionless quantity that is commonly used in differential geometry and surface thermodynamics, and can be easily calculated for different Laplacian drop shapes. The new definition of the shape parameter using the total Gaussian curvature is applied here to both pendant and constrained sessile drops as an illustration. The analysis showed that the new definition is superior and reflects experimental results better than previous definitions, especially at extreme values of the Bond number.
Combined Shape and Topology Optimization
DEFF Research Database (Denmark)
Christiansen, Asger Nyman
Shape and topology optimization seeks to compute the optimal shape and topology of a structure such that one or more properties, for example stiffness, balance or volume, are improved. The goal of the thesis is to develop a method for shape and topology optimization which uses the Deformable...... Simplicial Complex (DSC) method. Consequently, we present a novel method which combines current shape and topology optimization methods. This method represents the surface of the structure explicitly and discretizes the structure into non-overlapping elements, i.e. a simplicial complex. An explicit surface...... representation usually limits the optimization to minor shape changes. However, the DSC method uses a single explicit representation and still allows for large shape and topology changes. It does so by constantly applying a set of mesh operations during deformations of the structure. Using an explicit instead...
Envelope-Law and Geometric-Mean STAP Detection
Anitori, L.; Srinivasan, R.; Rangaswamy, M.
2010-01-01
Two detectors for space-time adaptive processing (STAP) are proposed here. These are variants that use envelope-law and geometric-mean (GM) (or logarithmic) processing, both being well-known concepts from conventional constant false alarm rate (CFAR) square-law radar detection [212]. The variants ar
Envelope-Law and Geometric-Mean STAP Detection
Anitori, L.; Srinivasan, R.; Rangaswamy, M.
2010-01-01
Two detectors for space-time adaptive processing (STAP) are proposed here. These are variants that use envelope-law and geometric-mean (GM) (or logarithmic) processing, both being well-known concepts from conventional constant false alarm rate (CFAR) square-law radar detection [212]. The variants
Stoddard, Nathan G
2015-02-10
Methods and apparatuses are provided for casting silicon for photovoltaic cells and other applications. With such methods and apparatuses, a cast body of geometrically ordered multi-crystalline silicon may be formed that is free or substantially free of radially-distributed impurities and defects and having at least two dimensions that are each at least about 10 cm is provided.
Improving Jet Reactor Configuration for Production of Carbon Nanotubes
Povitsky, Alex
2000-01-01
The jet mixing reactor has been proposed for the industrial production of fullerene carbon nanotubes. Here we study the flowfield of this reactor using the SIMPLER algorithm. Hot peripheral jets are used to enhance heating of the central jet by mixing with the ambiance of reactor. Numerous configurations of peripheral jets with various number of jets, distance between nozzles, angles between the central jet and a peripheral jets, and twisted configuration of nozzles are considered. Unlike the previous studies of jet mixing, the optimal configuration of peripheral jets produces strong non-uniformity of the central jet in a cross-section. The geometrical shape of reactor is designed to obtain a uniform temperature of a catalyst.
Percolation and cooperation with mobile agents: Geometric and strategy clusters
Vainstein, Mendeli H; Arenzon, Jeferson J
2014-01-01
We study the conditions for persistent cooperation in an off-lattice model of mobile agents playing the Prisoner's Dilemma game with pure, unconditional strategies. Each agent has an exclusion radius rP, which accounts for the population viscosity, and an interaction radius rint, which defines the instantaneous contact network for the game dynamics. We show that, differently from the rP=0 case, the model with finite-sized agents presents a coexistence phase with both cooperators and defectors, besides the two absorbing phases, in which either cooperators or defectors dominate. We provide, in addition, a geometric interpretation of the transitions between phases. In analogy with lattice models, the geometric percolation of the contact network (i.e., irrespective of the strategy) enhances cooperation. More importantly, we show that the percolation of defectors is an essential condition for their survival. Differently from compact clusters of cooperators, isolated groups of defectors will eventually become extin...
Kang, Ki Mun; Jeong, Bae Kwon; Choi, Hoon-Sik; Yoo, Seung Hoon; Hwang, Ui-Jung; Lim, Young Kyung; Jeong, Hojin
2015-09-08
We have investigated the combined effect of tissue heterogeneity and its variation associated with geometric error in stereotactic body radiotherapy (SBRT) for lung cancer. The treatment plans for eight lung cancer patients were calculated using effective path length (EPL) correction and Monte Carlo (MC) algorithms, with both having the same beam configuration for each patient. These two kinds of plans for individual patients were then subsequently recalculated with adding systematic and random geometric errors. In the ordinary treatment plans calculated with no geometric offset, the EPL calculations, compared with the MC calculations, largely overestimated the doses to PTV by ~ 21%, whereas the overestimation were markedly lower in GTV by ~ 12% due to relatively higher density of GTV than of PTV. When recalculating the plans for individual patients with assigning the systematic and random geometric errors, no significant changes in the relative dose distribution, except for overall shift, were observed in the EPL calculations, whereas largely altered in the MC calculations with a consistent increase in dose to GTV. Considering the better accuracy of MC than EPL algorithms, the present results demonstrated the strong coupling of tissue heterogeneity and geometric error, thereby emphasizing the essential need for simultaneous correction for tissue heterogeneity and geometric targeting error in SBRT of lung cancer.
Solar PV Energy Conversion System and its Configurations
Ahteshamul Haque
2016-01-01
Solar PV based energy conversion system is now used in commercial and residential buildings. Advancements in Power electronics leads the researchers to enhance the use of solar application in various configurations. These configurations may be used to utilize the energy optimally. The main objective of this paper is to present an overview of the various configurations of solar PV energy conversion system
Directory of Open Access Journals (Sweden)
Trunev A. P.
2014-05-01
Full Text Available In this article we have investigated the solutions of Maxwell's equations, Navier-Stokes equations and the Schrödinger associated with the solutions of Einstein's equations for empty space. It is shown that in some cases the geometric instability leading to turbulence on the mechanism of alternating viscosity, which offered by N.N. Yanenko. The mechanism of generation of matter from dark energy due to the geometric turbulence in the Big Bang has been discussed
Square and bow-tie configurations in the cyclic evasion problem
Arnold, M. D.; Golich, M.; Grim, A.; Vargas, L.; Zharnitsky, V.
2017-05-01
Cyclic evasion of four agents on the plane is considered. There are two stationary shapes of configurations: square and degenerate bow-tie. The bow-tie is asymptotically attracting while the square is of focus-center type. Normal form analysis shows that square is nonlinearly unstable. The stable manifold consists of parallelograms that all converge to the square configuration. Based on these observations and numerical simulations, it is conjectured that any non-parallelogram non-degenerate configuration converges to the bow-tie.
Mobile Geometric Graphs: Detection, Coverage and Percolation
Peres, Yuval; Sousi, Perla; Stauffer, Alexandre
2010-01-01
We consider the following dynamic Boolean model introduced by van den Berg, Meester and White (1997). At time 0, let the nodes of the graph be a Poisson point process in R^d with constant intensity and let each node move independently according to Brownian motion. At any time t, we put an edge between every pair of nodes if their distance is at most r. We study three features in this model: detection (the time until a target point---fixed or moving---is within distance r from some node of the graph), coverage (the time until all points inside a finite box are detected by the graph), and percolation (the time until a given node belongs to the infinite connected component of the graph). We obtain precise asymptotics for these features by combining ideas from stochastic geometry, coupling and multi-scale analysis.
Parallels plane projection and its geometric features
Institute of Scientific and Technical Information of China (English)
ZHOU ChengHu; MA Ting; YANG Liao; QIN Biao
2007-01-01
A new equivalent map projection called the parallels plane projection is proposed in this paper. The transverse axis of the parallels plane projection is the expansion of the equator and its vertical axis equals half the length of the central meridian. On the parallels plane projection, meridians are projected as sine curves and parallels are a series of straight, parallel lines. No distortion of length occurs along the central meridian or on any parallels of this projection. Angular distortion and the proportion of length along meridians (except the central meridian) introduced by the projection transformation increase with increasing longitude and latitude. A potential application of the parallels plane projection is that it can provide an efficient projection transformation for global discrete grid systems.
Geometric Monte Carlo and Black Janus Geometries
Bak, Dongsu; Kim, Kyung Kiu; Min, Hyunsoo; Song, Jeong-Pil
2016-01-01
We describe an application of the Monte Carlo method to the Janus deformation of the black brane background. We present numerical results for three and five dimensional black Janus geometries with planar and spherical interfaces. In particular, we argue that the 5D geometry with a spherical interface has an application in understanding the finite temperature bag-like QCD model via the AdS/CFT correspondence. The accuracy and convergence of the algorithm are evaluated with respect to the grid spacing. The systematic errors of the method are determined using an exact solution of 3D black Janus. This numerical approach for solving linear problems is unaffected initial guess of a trial solution and can handle an arbitrary geometry under various boundary conditions in the presence of source fields.
Gravity, Gauge Theories and Geometric Algebra
Lasenby, A; Gull, S F; Lasenby, Anthony; Doran, Chris; Gull, Stephen
1998-01-01
A new gauge theory of gravity is presented. The theory is constructed in a flat background spacetime and employs gauge fields to ensure that all relations between physical quantities are independent of the positions and orientations of the matter fields. In this manner all properties of the background spacetime are removed from physics, and what remains are a set of `intrinsic' relations between physical fields. The properties of the gravitational gauge fields are derived from both classical and quantum viewpoints. Field equations are then derived from an action principle, and consistency with the minimal coupling procedure selects an action that is unique up to the possible inclusion of a cosmological constant. This in turn singles out a unique form of spin-torsion interaction. A new method for solving the field equations is outlined and applied to the case of a time-dependent, spherically-symmetric perfect fluid. A gauge is found which reduces the physics to a set of essentially Newtonian equations. These e...
Topological and geometrical aspects of phase transitions
Santos, F. A. N.; Rehn, J. A.; Coutinho-Filho, M. D.
2014-03-01
In the first part of this review, we use a topological approach to describe the frustration- and field-induced phase transitions exhibited by the infinite-range XY model on the AB2 chain, including noncollinear spin structures. For this purpose, we have computed the Euler characteristic, χ, as well as other topological invariants, which are found to behave similarly as a function of the energy level in the context of Morse theory. Our findings and those available in the literature suggest that the cusp-like singularity exhibited by χ at the critical energy, Ec, put together with the divergence of the density of Jacobian's critical points emerge as necessary and sufficient conditions for the occurrence of finite-temperature topology-induced phase transitions. In the second part, we present an alternative solution of the Ising chain in a field under free and periodic boundary conditions, in the microcanonical, canonical, and grand canonical ensembles, from a unified combinatorial and topological perspective. In particular, the computation of the per-site entropy as a function of the energy unveils a residual value for critical values of the magnetic field, a phenomenon for which we provide a topological interpretation and a connection with the Fibonacci sequence. We also show that, in the thermodynamic limit, the per-site microcanonical entropy is equal to the logarithm of the per-site Euler characteristic. Finally, we emphasize that our combinatorial approach to the canonical ensemble allows exact computation of the thermally averaged value (T) of the Euler characteristic; our results show that the conjecture (Tc)= 0, where Tc is the critical temperature, is valid for the Ising chain.
Wavelets and Geometric Structure for Function Spaces
Institute of Scientific and Technical Information of China (English)
Qi Xiang YANG
2004-01-01
With Littlewood-Paley analysis, Peetre and Triebel classified, systematically, almost all the usual function spaces into two classes of spaces: Besov spaces (B)s,q p(s ∈ R,0 ＜ p,q ≤∞) and Triebel-Lizorkin spaces (F)s,q p(s∈R,0＜p＜∞,0＜q≤∞); but the structure of dual spaces (D)s,q p of (F)s,q p(s∈R, 0＜p≤1≤q≤∞) is very different from that of Besov spaces or that of Triebel-Lizorkin spaces, and their structure cannot be analysed easily in the Littlewood-Paley analysis. Our main goal is to characterize (D)s,q p (s ∈ R, 0＜p= 1≤q≤∞) in tent spaces with wavelets. By the way, some applications are given: (i) Triebel-Lizorkin spaces for p = ∞ defined by Littlewood-Paley analysis cannot serve as the dual spaces of Triebel-Lizorkin spaces for p = 1; (ii) Some inclusion relations among these above spaces and some relations among(B)o,q1,(F)o,q1 and L1 are studied.
Relationship between protein structure and geometrical constraints
DEFF Research Database (Denmark)
Lund, Ole; Hansen, Jan; Brunak, Søren;
1996-01-01
We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures...... using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the effect of using predicted secondary structure and surface assignments. The constraints used...... in this approach typically may be obtained from low-resolution experimental data. When using a cost function based on distances, half of the resulting structures will be mirrored, because the resulting structure and its mirror image will have the same cost. The secondary structure assignments were therefore...
Relationship between protein structure and geometrical constrains
DEFF Research Database (Denmark)
Lund, Ole; Hansen, Jan; Brunak, Søren;
1996-01-01
We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures...... using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the effect of using predicted secondary structure and surface assignments. The constraints used...... in this approach typically may be obtained from low-resolution experimental data. When using a cost function based on distances, half of the resulting structures will be mirrored, because the resulting structure and its mirror image will have the same cost. The secondary structure assignments were therefore...
French Romanticism and Napoleon's "Geometric Men."
Cole, Robert A.
1982-01-01
French intellectual thought changed during the Napoleonic Era. The effects of the Enlightenment philosophers, the French Revolution, the Industrial Revolution, and Romanticism on the development of Napoleon's philosophical outlook are used to illustrate the changes occurring in France as a whole in the early nineteenth century. (AM)
Geometrical hierarchy and spontaneous symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Farakos, K.; Koutsoumbas, G.; Surridge, M.; Zoupanos, G.
1987-06-04
A four-dimensional gauge theory, where Higgs fields and the corresponding potential appear naturally, is obtained by dimensionally reducing a pure gauge theory over a compact coset space S/R. We show, using an explicit example, that a hierarchy of the scales in the coset space can change the spontaneous symmetry breaking of the four-dimensional gauge theory.
Introduction to Geometric Dimensioning and Tolerancing.
Proebstle, Donald C.
Intended for drafting students in engineering drawing classes, the text provides basic definitions and explanations, as well as sample illustrations to be used as guides in dimensioning class projects by this technique. The content is divided into three units plus an appendix. Unit 1 discusses basic concepts, including the importance of the…
French Romanticism and Napoleon's "Geometric Men."
Cole, Robert A.
1982-01-01
French intellectual thought changed during the Napoleonic Era. The effects of the Enlightenment philosophers, the French Revolution, the Industrial Revolution, and Romanticism on the development of Napoleon's philosophical outlook are used to illustrate the changes occurring in France as a whole in the early nineteenth century. (AM)
Geometric Hamiltonian structures and perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Omohundro, S.
1984-08-01
We have been engaged in a program of investigating the Hamiltonian structure of the various perturbation theories used in practice. We describe the geometry of a Hamiltonian structure for non-singular perturbation theory applied to Hamiltonian systems on symplectic manifolds and the connection with singular perturbation techniques based on the method of averaging.
Geometric and Combinatorial Structure of Hypersurface Coamoebas
Nisse, Mounir
2009-01-01
Let $V$ be a complex algebraic hypersurface defined by a polynomial $f$ with Newton polytope $\\Delta$. It is well known that the spine of its amoeba has a structure of a tropical hypersurface. We prove in this paper that there exists a complex tropical hypersurface $V_{\\infty, f}$ such that its coamoeba is homeomorphic to the closure in the real torus of the coamoeba of $V$. Moreover, the coamoeba of $V_{\\infty, f}$ contains an arrangement of $(n-1)$-torus depending only on the geometry of $\\Delta$ and the coefficients of $f$. In addition, we can consider this arrangement, as a weighted codual hyperplanes arrangement in the universal covering of the real torus, and the balancing condition (the analogous to that of tropical hypersurfaces) is satisfied. This codual hyperplanes arrangement is called the {\\em shell} of the complex coamoeba (the cousin of the spine of the complex amoeba). %(or the {\\em average contour} of the complex coamoeba). Using this combinatorial coamoebas structure, we show that the amoebas...
Peace, Andrew J.; May, Nicholas E.; Pocock, Mark F.; Shaw, Jonathon A.
1994-04-01
This paper is concerned with the flow modelling capabilities of an advanced CFD simulation system known by the acronym SAUNA. This system is aimed primarily at complex aircraft configurations and possesses a unique grid generation strategy in its use of block-structured, unstructured or hybrid grids, depending on the geometric complexity of the addressed configuration. The main focus of the paper is in demonstrating the recently developed multi-grid, block-structured grid, viscous flow capability of SAUNA, through its evaluation on a number of configurations. Inviscid predictions are also presented, both as a means of interpreting the viscous results and with a view to showing more completely the capabilities of SAUNA. It is shown that accuracy and flexibility are combined in an efficient manner, thus demonstrating the value of SAUNA in aerodynamic design.
Jinno, Souma; Toki, Hiroshi; Abe, Masayoshi
2017-02-01
In this study, the coupling between the common and normal modes in distributed lines and the resulting electromagnetic noise were considered. The telegraph equations of three distributed lines with the boundary conditions of a lumped circuit reveal the presence of mode-coupling noise. To reduce the coupling noise, the geometrically and electrically symmetric configuration of the three distributed lines is proposed. The simulation results show that the proposed configuration can decrease the mode-coupling noise by a factor of 1 ×10-8 in comparison with that of asymmetric configurations.
Lauro Cesar Araujo; Mamede Lima-Marques
2016-01-01
Introduction: The term "configuration information" has emerged in the works of Information Architecture; however, there isn’t a conceptualization of “configuration” within Information Architecture. Objective: The objective is propose a definition for "configuration" and "information configuration" within the Information Architecture discipline, and indicate a teleological corpus from configuration management that can be used as paxis in Information Architecture. Methodolo...
Sensitivity and Resolution Capacity of Electrode Configurations
Directory of Open Access Journals (Sweden)
Cyril Chibueze Okpoli
2013-01-01
Full Text Available This paper reviews the geological conditions, data density, and acquisition geometry that have direct influence on the sensitivity and resolution capacity of several electrode configurations. The parameters appreciate the effectiveness of automated multichannel system which has evolved several electrode arrays that are cost effective, reduction in survey time, high sensitivity, and resolution capacity in 2D and 3D resistivity tomographies. The arrays are pole-pole, pole-dipole, pole-bipole, dipole-dipole, Wenner, Wenner-, , gradient, midpoint-potential-referred, Schlumberger, square, and Lee-partition arrays. The gradient array and midpoint-potential-referred are well suited for multichannel surveying and gradient array images are comparable to dipole-dipole and pole-dipole. 2D electrical resistivity surveys can produce out-of-plane anomaly of the subsurface which could be misleading in the interpretation of subsurface features. Hence, a 3D interpretation model should give more accurate results, because of the increase in the reliability of inversion images and complete elimination of spurious features. Therefore, the reduction of anomaly effects and damping factor due to signal to noise ratio result in better spatial resolution image, thus enhancing its usage in environmental and engineering research.
Methods and Apparatuses for Signaling with Geometric Constellations in a Raleigh Fading Channel
Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)
2015-01-01
Communication systems are described that use signal constellations, which have unequally spaced (i.e., `geometrically` shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR (signal to noise ratio). In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d (sub min) (i.e. minimum distance between constellations) are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.
Tread wear and footprint geometrical characters of truck bus radial tires
Liang, Chen; Wang, Guolin; An, Dengfeng; Ma, Yinwei
2013-05-01
Wear and mileage performance are the foremost performances for truck bus radial (TBR) tires. There are a lot of researches about the tire wear performance as well as the contact patch phenomenon by using finite element analysis (FEA) method or testing. But there is little published data on the correlations between the footprint geometry and the tread wear performance of tires. In this paper, an experiment on tire-ground performance of TBR tires is carried out by using Tekscan. The real-time changes of contact-area pressure distribution that occurred during the process of continuous load and unload are recorded. Three types of tires that act differently in behavior under normal usage are analyzed. A new method of researching in tire tread wear, which focuses on the geometrical characters of the footprint, is put forward. The experimental results of the three tires are described by using footprint geometrical characters. On the basis of studying the changing laws of footprint geometrical characters during the loading process and considering consumer survey and factory feedback information, the correlations between the geometrical character of footprints and tread destruction form are built. The analyzed results show that a greater contact area coefficient and a steady coefficient of contact result in a better wear performance for TBR tires. The footprint-shape coefficient changing laws in the process of loading are found to have a very good coincidence with the tread wear of the three types of tires. Tires with a smaller footprint-shape coefficient are likely to have an average tread wear while avoiding the shoulder wear first. The proposed research provides a new solution to predict tire-ground performance at the point of footprint and several useful references for improving tire design.
Human Mars Ascent Configuration and Design Sensitivities
Polsgrove, Tara P.; Gernhardt, Mike; Collins, Tim; Martin, John
2017-01-01
Human missions to Mars may utilize several small cabins where crew members could live for days up to a couple of weeks. At the end of a Mars surface mission the Mars Ascent Vehicle (MAV) crew cabin would carry the crew to their destination in orbit in a matter of hours or days. Other small cabins in support of a Mars mission would include pressurized rovers that allow crew members to travel great distances from their primary habitat on Mars while unconstrained by time limits of typical EVAs. An orbital crew taxi could allow for exploration of the moons of Mars with minimum impact to the primary Earth-Mars transportation systems. A common crew cabin design that can perform in each of these applications is desired and could reduce the overall mission cost. However, for the MAV, the crew cabin size and mass can have a large impact on vehicle design and performance. The total ascent vehicle mass drives performance requirements for the Mars descent systems and the Earth to Mars transportation elements. Minimizing MAV mass is a priority and minimizing the crew cabin size and mass is one way to do that. This paper explores the benefits and impacts of using a common crew cabin design for the MAV. Results of a MAV configuration trade study will be presented along with mass and performance estimates for the selected design.
Configuration Studies and Recommendations for the ILC DampingRings
Energy Technology Data Exchange (ETDEWEB)
Wolski, Andrzej; Gao, Jie; Guiducci, Susanna
2006-02-04
We describe the results of studies comparing different options for the baseline configuration of the ILC damping rings. The principal configuration decisions apply to the circumference, beam energy, lattice type, and technology options for key components, including the injection/extraction kickers and the damping wigglers. To arrive at our recommended configuration, we performed detailed studies of a range of lattices representing a variety of different configuration options; these lattices are described in Chapter 2. The results of the various studies are reported in chapters covering issues of beam dynamics, technical subsystems, costs, and commissioning, reliability and upgrade ability. Our detailed recommendations for the baseline configuration are given in Chapter 7, where we also outline further research and development that is needed before a machine using our recommended configuration can be built and operated successfully. In the same chapter, we suggest possible alternatives to the baseline configuration.
Coexisting shape- and high-K isomers in the shape transitional nucleus {sup 188}Pt
Energy Technology Data Exchange (ETDEWEB)
Mukhopadhyay, S., E-mail: somm@barc.gov.in [Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Biswas, D.C. [Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Tandel, S.K. [UM-DAE Centre for Excellence in Basic Sciences, Mumbai 400098 (India); Danu, L.S.; Joshi, B.N.; Prajapati, G.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Nag, Somnath [Dept. of Physics, IIT Kharagpur, Kharagpur 721302 (India); Trivedi, T.; Saha, S.; Sethi, J.; Palit, R. [Dept. of Nuclear and Atomic Physics, TIFR, Mumbai 400005 (India); Joshi, P.K. [Homi Bhabha Centre for Science Education, TIFR, Mumbai 400088 (India)
2014-12-12
A high-spin study of the shape transitional nucleus {sup 188}Pt reveals the unusual coexistence of both shape- and K-isomeric states. Reduced B(E2) transition probabilities for decays from these states inferred from the data clearly establish their hindered character. In addition to other excited structures, a rotational band built upon the K isomer is identified, and its configuration has been assigned through an analysis of alignments and branching ratios. The shape evolution with spin in this nucleus has been inferred from both experimental observables and cranking calculations. The yrast positive parity structure appears to evolve from a near-prolate deformed shape through triaxial at intermediate excitation, and eventually to oblate at the highest spins.
An Efficient Algorithm for Calculating Aircraft RCS Based on the Geometrical Characteristics
Institute of Scientific and Technical Information of China (English)
Gao Zhenghong; Wang Mingliang
2008-01-01
Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method (SMM), is proposed to calculate radar cross section (RCS) of aircraft configuration. Based on the geometrical characteristics and the method of moment (MOM), the SMM points out that the strong current coupling zone could be predefined according to the shape of scatterers. Two geometrical parameters, the surface curvature and the electrical space between the field position and source position, are deducted to distinguish the dominant current coupling. Then the strong current coupling is computed to construct an impedance matrix having sparse nature, which is solved to compute RCS. The efficiency and feasibility of the SMM are demonstrated by computing electromagnetic scattering of some kinds of shapes such as a cone-sphere with a gap, a bi-arc column and a stealth aircraft configuration.The numerical results show that: (1) the accuracy of SMM is satisfied, as compared with MOM, and the computational time it spends is only about 8% of the MOM; (2) with the electrical space considered, making another allowance for the surface curvature can reduce the computation time by 9.5%.
Functional and shape data analysis
Srivastava, Anuj
2016-01-01
This textbook for courses on function data analysis and shape data analysis describes how to define, compare, and mathematically represent shapes, with a focus on statistical modeling and inference. It is aimed at graduate students in analysis in statistics, engineering, applied mathematics, neuroscience, biology, bioinformatics, and other related areas. The interdisciplinary nature of the broad range of ideas covered—from introductory theory to algorithmic implementations and some statistical case studies—is meant to familiarize graduate students with an array of tools that are relevant in developing computational solutions for shape and related analyses. These tools, gleaned from geometry, algebra, statistics, and computational science, are traditionally scattered across different courses, departments, and disciplines; Functional and Shape Data Analysis offers a unified, comprehensive solution by integrating the registration problem into shape analysis, better preparing graduate students for handling fu...
Optimal Geometric Partitions, Covers and K-Centers
Andreica, Mugurel Ionut; Andreica, Cristina Teodora; Andreica, Romulus; Ungureanu, Mihai Aristotel
2009-01-01
In this paper we present some new, practical, geometric optimization techniques for computing polygon partitions, 1D and 2D point, interval, square and rectangle covers, as well as 1D and 2D interval and rectangle K-centers. All the techniques we present have immediate applications to several cost optimization and facility location problems which are quite common in practice. The main technique employed is dynamic programming, but we also make use of efficient data structures and fast greedy algorithms.
Polarization ellipse and Stokes parameters in geometric algebra.
Santos, Adler G; Sugon, Quirino M; McNamara, Daniel J
2012-01-01
In this paper, we use geometric algebra to describe the polarization ellipse and Stokes parameters. We show that a solution to Maxwell's equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the wave function arguments from complex scalars to complex vectors. This conversion allows us to separate the electric field vector and the imaginary magnetic field vector, because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while exponentials of imaginary vectors only rotate the vector or imaginary vector they are multiplied to. We convert this expression for polarized light into two other representations: the Cartesian representation and the rotated ellipse representation. We compute the conversion relations among the representation parameters and their corresponding Stokes parameters. And finally, we propose a set of geometric relations between the electric and magnetic fields that satisfy an equation similar to the Poincaré sphere equation.
Honzík, Petr; Podkovskiy, Alexey; Durand, Stéphane; Joly, Nicolas; Bruneau, Michel
2013-11-01
The main purpose of the paper is to contribute at presenting an analytical and a numerical modeling which would be relevant for interpreting the couplings between a circular membrane, a peripheral cavity having the same external radius as the membrane, and a thin air gap (with a geometrical discontinuity between them), and then to characterize small scale electrostatic receivers and to propose procedures that could be suitable for fitting adjustable parameters to achieve optimal behavior in terms of sensitivity and bandwidth expected. Therefore, comparison between these theoretical methods and characterization of several shapes is dealt with, which show that the models would be appropriate to address the design of such transducers.
A Kind of Visual Speech Feature with the Geometric and Local Inner Texture Description
Directory of Open Access Journals (Sweden)
Yanfeng Sun
2013-02-01
Full Text Available In this paper, we propose a type of joint feature with geometric parameters and color moments to represent the speaking-mouth frames for image-based visual speech synthesis systems. Based on FDP around the mouth area, the geometric feature is obtained by computing Euclidean distances to describe the width of the speaking mouth, the height of the outer and inner lips and the distances between them. The color moment component in the joint feature is obtained by calculating the texture between the upper and lower inner lips to describe the visibility state of the teeth. Through analyzing the accordance between the teeth visibility and the components of RGB and HSV color space based on the samples separately, we discovered that green and blue components are good at describing the change of teeth visibility. The experiments show that the proposed joint feature can effectively provide the basis for categorizing the different speaking states especially at the sense of lip shapes and tooth visibility. The evaluation of clustering results is done by analyzing the derived parameters of the silhouette function. The analyzing results prove that comparing with the geometric only and PCA, our proposed feature together with the shape and the local inner lip texture clues has better performance in improving the similarity between samples within the clusters. In the future, more expressive features with the shape and local texture information should be explored to increase the proportion of similar samples within the clusters to improve the descriptive ability of speaking mouths.