Bökstedt, Marcel
2016-01-01
We study a novel type of braid groups on a closed orientable surface $\\Sigma$. These are fundamental groups of certain manifolds that are hybrids between symmetric products and configuration spaces of points on $\\Sigma$; a class of examples arises naturally in gauge theory, as moduli spaces of vortices in toric fibre bundles over $\\Sigma$. The elements of these braid groups, which we call divisor braids, have coloured strands that are allowed to intersect according to rules specified by a graph $\\Gamma$. In situations where there is more than one strand of each colour, we show that the corresponding braid group admits a metabelian presentation as a central extension of the free Abelian group $H_1(\\Sigma;\\mathbb{Z})^{\\oplus r}$, where $r$ is the number of colours, and describe its Abelian commutator. This computation relies crucially on producing a link invariant (of closed divisor braids) in the three-manifold $S^1 \\times \\Sigma $ for each graph $\\Gamma$. We also describe the von Neumann algebras associated t...
Braided Clifford algebras as braided quantum groups
Durdevic, M
1995-01-01
The paper deals with braided Clifford algebras, understood as Chevalley-Kahler deformations of braided exterior algebras. It is shown that Clifford algebras based on involutive braids can be naturally endowed with a braided quantum group structure. Basic group entities are constructed explicitly.
Unprovability results involving braids
Carlucci, Lorenzo; Weiermann, Andreas
2007-01-01
We construct long sequences of braids that are descending with respect to the standard order of braids (``Dehornoy order''), and we deduce that, contrary to all usual algebraic properties of braids, certain simple combinatorial statements involving the braid order are true, but not provable in the subsystems ISigma1 or ISigma2 of the standard Peano system.
Hamilton, Linus
2014-01-01
Braid is a 2008 puzzle game centered around the ability to reverse time. We show that Braid can simulate an arbitrary computation. Our construction makes no use of Braid's unique time mechanics, and therefore may apply to many other video games. We also show that a plausible "bounded" variant of Braid lies within 2-EXPSPACE. Our proof relies on a technical lemma about Turing machines which may be of independent interest. Namely, define a braidlike Turing machine to be a Turing machine that, w...
van den Berg, J. B.; Ghrist, R.; Vandervorst, R. C.; Wójcik, W.
2015-09-01
Area-preserving diffeomorphisms of a 2-disc can be regarded as time-1 maps of (non-autonomous) Hamiltonian flows on R / Z ×D2. The periodic flow-lines define braid (conjugacy) classes, up to full twists. We examine the dynamics relative to such braid classes and define a new invariant for such classes, the BRAID FLOER HOMOLOGY. This refinement of Floer homology, originally used for the Arnol'd Conjecture, yields a Morse-type forcing theory for periodic points of area-preserving diffeomorphisms of the 2-disc based on braiding. Contributions of this paper include (1) a monotonicity lemma for the behavior of the nonlinear Cauchy-Riemann equations with respect to algebraic lengths of braids; (2) establishment of the topological invariance of the resulting braid Floer homology; (3) a shift theorem describing the effect of twisting braids in terms of shifting the braid Floer homology; (4) computation of examples; and (5) a forcing theorem for the dynamics of Hamiltonian disc maps based on braid Floer homology.
Roy, Sutanu
2016-01-01
We propose a general theory of braided quantum groups in the C*-algebraic framework. More precisely, we construct braided quantum groups using manageable braided multiplicative unitaries over a regular C*-quantum group. We show that braided C*-quantum groups are equivalent to C*-quantum groups with projection.
Decoupling braided tensor factors
International Nuclear Information System (INIS)
It is shown that the braided tensor product algebra of two module algebras A1, A2 of a quasitriangular Hopf algebra is equal to the ordinary tensor product algebra of A1 with a subalgebra isomorphic to A2 and commuting with A1. As applications of the theorem the braided tensor product algebras of two or more quantum group covariant quantum space or deformed Heisenberg algebras are considered
On braid monodromy factorizations
Energy Technology Data Exchange (ETDEWEB)
Kharlamov, V M [Institut de Recherche Matematique Avanee Universite Louis Pasteur et CNRS 7 rue Rene Descartes (France); Kulikov, Vik S [Steklov Mathematical Institute, Russian Academy of Sciences (Russian Federation)
2003-06-30
We introduce and develop a language of semigroups over the braid groups to study the braid monodromy factorizations (bmf's) of plane algebraic curves and other related objects. As an application, we give a new proof of Orevkov's theorem on the realization of bmf's over a disc by algebraic curves and show that the complexity of such a realization cannot be bounded in terms of the types of factors of the bmf. We also prove that the type of a bmf distinguishes Hurwitz curves with singularities of inseparable type up to H-isotopy and J-holomorphic cuspidal curves in CP{sup 2} up to symplectic isotopy.
Bicharacters, braids and Jacobi identity
Rozansky, L
1996-01-01
For an abelian group G we consider braiding in a category of G-graded modules $M^{kG}$ given by a bicharacter \\chi on G. For $(G,\\chi)$-bialgebra A in $M^{kG}$ an analog of Lie bracket is defined. This bracket is determined by a linear map $E\\in\\End(A)$ and n-ary operations $\\Omega^{n}_{E}$ on A. Our result states that if $E(1)=0,E^{2}=0$ and $\\Omega^{3}_{E}=0$ then a braided Jacobi identity holds and the linear map E is a braided derivation of a braided Lie algebra.
Dynnikov coordinates on virtual braid groups
Bardakov, Valerij G; Wiest, Bert
2011-01-01
We define Dynnikov coordinates on virtual braid groups. We prove that they are faithful invariants of virtual 2-braids, and present evidence that they are also very powerful invariants for general virtual braids.
Gonzalez-Meneses, Juan
2010-01-01
These are Lecture Notes of a course given by the author at the French-Spanish School "Tresses in Pau", held in Pau (France) in October 2009. It is basically an introduction to distinct approaches and techniques that can be used to show results in braid groups. Using these techniques we provide several proofs of well known results in braid groups, namely the correctness of Artin's presentation, that the braid group is torsion free, or that its center is generated by the full twist. We also recall some solutions of the word and conjugacy problems, and that roots of a braid are always conjugate. We also describe the centralizer of a given braid. Most proofs are classical ones, using modern terminology. I have chosen those which I find simpler or more beautiful.
Group theory analysis of braided geometry structures
Institute of Scientific and Technical Information of China (English)
FENG Wei; MA Wensuo
2005-01-01
The braided geometry structures are analyzed with point groups and space groups for which the continuous yarn of the braided preforms is segmented and expressed in some special symbols. All structures of braided material are described and classified with group theory, and new braiding methods are found. The group theory analysis lays the theoretical foundation for optimizing material performance.
Cable Braid Electromagnetic Penetration Model.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry K. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Langston, William L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Basilio, Lorena I. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Johnson, W. A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
2015-06-01
The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles and reciprocity for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also setup in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multipoles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplified infinite periodic planar geometry. This is used in a simplified application of reciprocity to be able to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.
Duality principle and braided geometry
Majid, S
1994-01-01
We give an overview of a new kind symmetry in physics which exists between observables and states and which is made possible by the language of Hopf algebras and quantum geometry. It has been proposed by the author as a feature of Planck scale physics. More recent work includes corresponding results at the semiclassical level of Poisson-Lie groups and at the level of braided groups and braided geometry.
Kerler, T
1994-01-01
We investigate invertible elements and gradings in braided tensor categories. This leads us to the definition of theta-, product-, subgrading and orbitcategories in order to construct new families of BTC's from given ones. We use the representation theory of Hecke algebras in order to relate the fusionring of a BTC generated by an object $X$ with a two component decomposition of its tensorsquare to the fusionring of quantum groups of type $A$ at roots of unity. We find the condition of "local isomorphie" on a special fusionring morphism implying that a BTC is obtained from the above constructions applied to the semisimplified representation category of a quantum group. This family of BTC's contains new series of twisted categories that do not stem from known Hopf algebras. Using the language of incidence graphs and the balancing structure on a BTC we also find strong constraints on the fusionring morphism. For Temperley Lieb type categories these are sufficient to show local isomorphie. Thus we obtain a class...
Permutation Analysis of Track and Column Braiding
Institute of Scientific and Technical Information of China (English)
李毓陵; 丁辛; 胡良剑
2004-01-01
The positions of braiding carrier in track and column braiding are represented by a diagrammatic braiding plan and a corresponding lattice-array is defined. A set is then formed so that the permutation analysis can be performed to represent the movement of carriers in a braiding process. The process of 4-step braiding is analyzed as an example to describe the application of the proposed method by expressing a braiding cycle as a product of disjoint cycles. As a result, a mapping relation between the disjoint cycles and the movement of carriers is deduced. Following the same analysis principles, a process of 8-step braiding and the corresponding initial state of the lattice-array is developed. A successful permutation analysis to the process manifests the general suitability of the proposed method.
The Picard crossed module of a braided tensor category
Davydov, Alexei; Nikshych, Dmitri
2012-01-01
For a finite braided tensor category we introduce its Picard crossed module consisting of the group of invertible module categories and the group of braided tensor autoequivalences. We describe the Picard crossed module in terms of braided autoequivalences of the Drinfeld center of the braided tensor category. As an illustration, we compute the Picard crossed module of a braided pointed fusion category.
Braided nodal lines in wave superpositions
Dennis, M R
2003-01-01
Nodal lines (phase singularities, optical vortices) are the generic interference fringes of complex scalar waves. Here, an exact complex solution of the time independent wave equation (Helmholtz equation) is considered, possessing nodal lines which are braided in the form of a borromean, or pig-tail braid. The braid field is a superposition of counterpropagating, counterrotating, non-coaxial order 3 Bessel beams, and a plane wave whose propagation is perpendicular to that of the beams. The construction is structurally stable, and can be generalized to a limited class of other braids.
A yarn interaction model for circular braiding
Ravenhorst, van J.H.; Akkerman, R.
2016-01-01
Machine control data for the automation of the circular braiding process has been generated using previously published mathematical models that neglect yarn interaction. This resulted in a significant deviation from the required braid angle at mandrel cross-sectional changes, likely caused by an inc
Emergent Braided Matter of Quantum Geometry
Directory of Open Access Journals (Sweden)
Sundance Bilson-Thompson
2012-03-01
Full Text Available We review and present a few new results of the program of emergent matter as braid excitations of quantum geometry that is represented by braided ribbon networks. These networks are a generalisation of the spin networks proposed by Penrose and those in models of background independent quantum gravity theories, such as Loop Quantum Gravity and Spin Foam models. This program has been developed in two parallel but complimentary schemes, namely the trivalent and tetravalent schemes. The former studies the braids on trivalent braided ribbon networks, while the latter investigates the braids on tetravalent braided ribbon networks. Both schemes have been fruitful. The trivalent scheme has been quite successful at establishing a correspondence between braids and Standard Model particles, whereas the tetravalent scheme has naturally substantiated a rich, dynamical theory of interactions and propagation of braids, which is ruled by topological conservation laws. Some recent advances in the program indicate that the two schemes may converge to yield a fundamental theory of matter in quantum spacetime.
Systematically generated two-qubit anyon braids
Carnahan, Caitlin; Zeuch, Daniel; Bonesteel, N. E.
2016-05-01
Fibonacci anyons are non-Abelian particles for which braiding is universal for quantum computation. Reichardt has shown how to systematically generate nontrivial braids for three Fibonacci anyons which yield unitary operations with off-diagonal matrix elements that can be made arbitrarily small in a particular natural basis through a simple and efficient iterative procedure. This procedure does not require brute force search, the Solovay-Kitaev method, or any other numerical technique, but the phases of the resulting diagonal matrix elements cannot be directly controlled. We show that despite this lack of control the resulting braids can be used to systematically construct entangling gates for two qubits encoded by Fibonacci anyons.
Detecting coherent structures using braids
Allshouse, Michael R
2011-01-01
The detection of coherent structures is an important problem in fluid dynamics, particularly in geophysical applications. For instance, knowledge of how regions of fluid are isolated from each other allows prediction of the ultimate fate of oil spills. Existing methods detect Lagrangian coherent structures, which are barriers to transport, by examining the stretching field as given by finite-time Lyapunov exponents. These methods are very effective when the velocity field is well-determined, but in many applications only a small number of flow trajectories are known, for example when dealing with oceanic float data. We introduce a topological method for detecting invariant regions based on a small set of trajectories. In the method we regard the two-dimensional trajectory data as a braid in three dimensions, with time being the third coordinate. Invariant regions then correspond to trajectories that travel together and do not entangle other trajectories. We detect these regions by examining the growth of hypo...
Braided magnetic fields: equilibria, relaxation and heating
Pontin, D. I.; Candelaresi, S.; Russell, A. J. B.; Hornig, G.
2016-05-01
We examine the dynamics of magnetic flux tubes containing non-trivial field line braiding (or linkage), using mathematical and computational modelling, in the context of testable predictions for the laboratory and their significance for solar coronal heating. We investigate the existence of braided force-free equilibria, and demonstrate that for a field anchored at perfectly-conducting plates, these equilibria exist and contain current sheets whose thickness scales inversely with the braid complexity—as measured for example by the topological entropy. By contrast, for a periodic domain braided exact equilibria typically do not exist, while approximate equilibria contain thin current sheets. In the presence of resistivity, reconnection is triggered at the current sheets and a turbulent relaxation ensues. We finish by discussing the properties of the turbulent relaxation and the existence of constraints that may mean that the final state is not the linear force-free field predicted by Taylor’s hypothesis.
Symmetric centres of braided monoidal categories
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
This paper introduces the concept of‘symmetric centres' of braided monoidal categories. Let H be a Hopf algebra with bijective antipode over a field k. We address the symmetric centre of the Yetter-Drinfel'd module category HH(yD) and show that a left Yetter-Drinfel'd module M belongs to the symmetric centre of HH(yD) if and only if M is trivial. We also study the symmetric centres of categories of representations of quasitriangular Hopf algebras and give a sufficient and necessary condition for the braid of H(M) to induce the braid of (H(H)(A),(○)A,A,φ,l,r), or equivalently, the braid of (A#H(H),(○)A,A,φ,l,r), where A is a quantum commutative H-module algebra.
Infinitesimal 2-braidings and differential crossed modules
Cirio, Lucio S
2013-01-01
We categorify the notion of an infinitesimal braiding in a linear strict symmetric monoidal category, leading to the notion of a (strict) infinitesimal 2-braiding in a linear symmetric strict monoidal 2-category. We describe the associated categorification of the 4-term relation, leading to six categorified relations. We prove that any infinitesimal 2-braiding gives rise to a flat and fake flat 2-connection in the configuration space of $n$ undistinguishable particles in the complex plane, hence to a categorification of the Knizhnik-Zamolodchikov connection. We discuss infinitesimal 2-braidings in a category naturally assigned to every differential crossed module, leading to the notion of a quasi-invariant tensor in a differential crossed module. Finally we prove that quasi-invariant tensors exist in the differential crossed module associated to the string Lie-2-algebra.
Braided magnetic fields: equilibria, relaxation and heating
Pontin, D I; Russell, A J B; Hornig, G
2015-01-01
We examine the dynamics of magnetic flux tubes containing non-trivial field line braiding (or linkage), using mathematical and computational modelling. The key results obtained from recent modelling efforts are summarised, in the context of testable predictions for the laboratory. We discuss the existence of braided force-free equilibria, and demonstrate that for a field anchored at perfectly-conducting plates, these equilibria exist and contain current sheets whose thickness scales inversely with the braid complexity - as measured for example by the topological entropy. By contrast, for a periodic domain braided exact equilibria typically do not exist, while approximate equilibria contain thin current sheets. In the presence of resistivity, reconnection is triggered at the current sheets and a turbulent relaxation ensues. We discuss the properties of this relaxation, and in particular the existence of constraints that may mean that the final state is not the linear force-free field predicted by Taylor's hypo...
Modelling planform changes of braided rivers
Jagers, Hendrik Reinhard Albert
2003-01-01
This study has focused on modelling techniques to predict planform changes of braided rivers and their relation with state-of-the-art knowledge on the physical processes and the availability of model input data
Concrete reinforced by braided fibre composite rods
Fangueiro, Raúl; Sousa, Guilherme José Miranda de; Soutinho, Hélder Filipe Cunha; Jalali, Said; Araújo, Mário Duarte de
2005-01-01
One of the most serious problems affecting concrete is corrosion of the steel reinforcement. Corrosion may occur due to reaction of lime present in hydrated cement with carbon dioxide or to the action of chlorides. The braiding technique is probably the most ancient production process for textile structures. Normally used for ropes and cables, braided fabrics are also very interesting for composite reinforcements due to their characteristics: in-plane multiaxial ...
Self-diagnosing braided composite rod
Fangueiro, Raúl; Zdraveva, E.; Pereira, Cristiana Gonilho; Ferreira, A.; Lanceros-Méndez, S.
2010-01-01
This paper presents the development of a braided reinforced composite rod (BCR) able to both reinforce and monitor the stress state of concrete structures. Carbon fibers have been used as sensing and reinforcing materials along with glass fiber. Various composites rods have been produced using an author patented technique based on a modified conventional braiding machine. The materials investigated were prepared with different carbon fiber content as follows: BCR2 (77% glass/23...
Diagrammatics of braided group gauge theory
Majid, S
1996-01-01
We develop a gauge theory or theory of bundles and connections on them at the level of braids and tangles. Extending recent algebraic work, we provide now a fully diagrammatic treatment of principal bundles, a theory of global gauge transformations, associated braided fiber bundles and covariant derivatives on them. We describe the local structure for a concrete Z_3-graded or `anyonic' realization of the theory.
Braided rings a scattering billiard model
Bénet, L
1999-01-01
We introduce a billiard scattering model consisting of two non-overlapping rotating discs in the context of the formation and structural properties of planetary rings. We show that due to the arrangement of the symmetric periodic orbits, stable orbits are found which in the configuration space lead to the appearance of patterns qualitatively similar to planetary rings. Rings associated with different stability regions are naturally braided; different braids may overlap displaying features similar to clumps. Erosion mechanisms within the model are discussed.
Minimal Braid in Applied Symbolic Dynamics
Institute of Scientific and Technical Information of China (English)
张成; 张亚刚; 彭守礼
2003-01-01
Based on the minimal braid assumption, three-dimensional periodic flows of a dynamical system are reconstructed in the case of unimodal map, and their topological structures are compared with those of the periodic orbits of the Rossler system in phase space through the numerical experiment. The numerical results justify the validity of the minimal braid assumption which provides a suspension from one-dimensional symbolic dynamics in the Poincare section to the knots of three-dimensional periodic flows.
On braided Poisson and quantum inhomogeneous groups
Zakrzewski, S.
1997-01-01
The well known incompatibility between inhomogeneous quantum groups and the standard q-deformation is shown to disappear (at least in certain cases) when admitting the quantum group to be braided. Braided quantum ISO(p,N-p) containing SO_q(p,N-p) with |q|=1 are constructed for N=2p, 2p+1, 2p+2. Their Poisson analogues (obtained first) are presented as an introduction to the quantum case.
Fan deltas and braid deltas: conceptual problems
Energy Technology Data Exchange (ETDEWEB)
McPherson, J.G.; Shanmugam, G.; Moiola, R.J.
1986-05-01
The concept of fan deltas has been widely misinterpreted in the geologic literature. A true fan delta is defined as an alluvial fan deposited into a standing body of water. Such sequences are of limited areal extent and are, as expected, uncommon in the rock record. By contrast, braid deltas (herein defined), formed by progradation of a braided fluvial system into a standing body of water, are a common geomorphic feature in many modern settings, and their deposits are common in the geologic record. Braid-delta sequences are often identified as fan deltas, on the false premise that coarse-grained deposits in a deltaic setting are always part of an alluvial fan complex. The authors find that most published examples of so called fan deltas contain no direct evidence for the presence of an alluvial fan. Even in examples where an alluvial fan could be documented, the authors found that, in many cases, the alluvial fan complex was far removed from the shoreline, separated by an extensive braid plain. The authors suggest that such systems are better classified as braid deltas. They consider that it is essential to distinguish the environmental setting of true fan deltas from that of braid deltas. Misclassification will lead to incorrect interpretations of expected facies, sandstone geometry, reservoir quality, and tectonic settings. Criteria based on geometry, vertical and lateral lithofacies associations, and paleocurrent patterns should be used to correctly identify and distinguish these depositional systems.
In Vitro Degradation of Polyglycolide/Chitosan Hybrid Braids
Institute of Scientific and Technical Information of China (English)
YUAN Xiaoyan; ZHANG Qingwei; WANG Yonglin; YAO Kangde
2005-01-01
Hybrid braids of polyglycolide (PGA) and chitosan were prepared by the three-yarn braiding method from PGA and chitosan fiber bundles. These braids were in vitro degraded by incubating them in phosphate buffered saline (PBS) at pH 7.4 and 37 ℃ for 5 weeks. Results suggested that PGA/chitosan hybrid braids degraded significantly. Scanning electron micrographs showed that chitosan fibers in the PGA/chitosan hybrid braid with about 750% PGA in weight (PGA75/chitosan) were shaped into gel-like after 5 weeks, but those in the hybrid braid with about 250% PGA in weight (PGA25/chitosan) did not change. After 5 weeks, the ultimate tensile loads of PGA and PGA75/chitosan braids lost almost completely, but those of chitosan and PGA25/chitosan braids remained around 14 N. The PGA/chitosan hybrid braids with higher initial ultimate tensile load would have potential applications in tendon/ligament tissue reconstruction.
Internal Strain Measurement in 3D Braided Composites Using Co-braided Optical Fiber Sensors
Institute of Scientific and Technical Information of China (English)
Shenfang YUAN; Rui HUANG; Yunjiang RAO
2004-01-01
3D braided composite technology has stimulated a great deal of interest in the world at large. But due to the threedimensional nature of these kinds of composites, coupled with the shortcomings of currently-adopted experimental test methods, it is difficult to measure the internal parameters of this materials, hence causes it difficult to understand the material performance. A new method is introduced herein to measure the internal strain of braided composite materials using co-braided fiber optic sensors. Two kinds of fiber optic sensors are co-braided into 3D braided composites to measure internal strain. One of these is the Fabry-Parrot (F-P) fiber optic sensor; the other is the polarimetric fiber optic sensor. Experiments are conducted to measure internal strain under tension, bending and thermal environments in the 3D carbon fiber braided composite specimens, both locally and globally. Experimental results show that multiple fiber optic sensors can be braided into the 3D braided composites to measure the internal parameters, providing a more accurate measurement method and leading to a better understanding of these materials.
Geometrical deployment for braided stent.
Bouillot, Pierre; Brina, Olivier; Ouared, Rafik; Yilmaz, Hasan; Farhat, Mohamed; Erceg, Gorislav; Lovblad, Karl-Olof; Vargas, Maria Isabel; Kulcsar, Zsolt; Pereira, Vitor Mendes
2016-05-01
The prediction of flow diverter stent (FDS) implantation for the treatment of intracranial aneurysms (IAs) is being increasingly required for hemodynamic simulations and procedural planning. In this paper, a deployment model was developed based on geometrical properties of braided stents. The proposed mathematical description is first applied on idealized toroidal vessels demonstrating the stent shortening in curved vessels. It is subsequently generalized to patient specific vasculature predicting the position of the filaments along with the length and local porosity of the stent. In parallel, in-vitro and in-vivo FDS deployments were measured by contrast-enhanced cone beam CT (CBCT) in idealized and patient-specific geometries. These measurements showed a very good qualitative and quantitative agreement with the virtual deployments and provided experimental validations of the underlying geometrical assumptions. In particular, they highlighted the importance of the stent radius assessment in the accuracy of the deployment prediction. Thanks to its low computational cost, the proposed model is potentially implementable in clinical practice providing critical information for patient safety and treatment outcome assessment. PMID:26891065
Equilibrium theory for braided elastic filaments
van der Heijden, Gert
Motivated by supercoiling of DNA and other filamentous structures, we formulate a theory for equilibria of 2-braids, i.e., structures formed by two elastic rods winding around each other in continuous contact and subject to a local interstrand interaction. Unlike in previous work no assumption is made on the shape of the contact curve. Rather, this shape is found as part of the solution. The theory is developed in terms of a moving frame of directors attached to one of the strands with one of the directors pointing to the position of the other strand. The constant-distance constraint is automatically satisfied by the introduction of what we call braid strains. The price we pay is that the potential energy involves arclength derivatives of these strains, thus giving rise to a second-order variational problem. The Euler-Lagrange equations for this problem give balance equations for the overall braid force and moment referred to the moving frame as well as differential equations that can be interpreted as effective constitutive relations encoding the effect that the second strand has on the first as the braid deforms under the action of end loads. Simple analytical cases are discussed first and used as starting solutions in parameter continuation studies to compute classes of both open and closed (linked or knotted) braid solutions.
Tensile performance of braided composite rods for concrete reinforcement
Pereira, Cristiana Gonilho; Fangueiro, Raúl; Jalali, Said; Araújo, Mário Duarte de; Marques, P.
2008-01-01
The current work is concerned with the development of braided composite rods for civil engineering applications, namely for concrete internal reinforcement, as a steel substitute. The research study aims at understanding the tensile behaviour of composite rods reinforced by a textile structure – braided structure with core reinforcement. Seven types of braided composite rods were produced, varying the type of fibres used as a core reinforcement of a polyester braided structure. Eglass, car...
Braided composite rods to reinforce concrete subjected to aggressive environments
Pereira, Cristiana Gonilho; Fangueiro, Raúl; Jalali, Said; Marques, P.; Araújo, Mário Duarte de
2008-01-01
The current work is concerned with the development of braided composite rods for civil engineering applications, namely for concrete internal reinforcement, as a steel substitute. The research study aims at understanding the tensile behaviour of composite rods reinforced by a textile structure – braided structure with core reinforcement. Seven types of braided composite rods were produced, varying the type of fibres used as a core reinforcement of a polyester braided structure. E-glass, ca...
On Vassiliev invariants of braid groups of the sphere
Kaabi, N
2012-01-01
We construct a universal Vassiliev invariant for braid groups of the sphere and the mapping class groups of the sphere with $n$ punctures. The case of a sphere is different from the classical braid groups or braids of oriented surfaces of genus strictly greater than zero, since Vassiliev invariants in a group without 2-torsion do not distinguish elements of braid group of a sphere.
Integrated Design for Manufacturing of Braided Preforms for Advanced Composites Part I: 2D Braiding
Gao, Yan Tao; Ko, Frank K.; Hu, Hong
2013-12-01
This paper presents a 2D braiding design system for advanced textile structural composites was based on dynamic models. A software package to assist in the design of braided preform manufacturing has been developed. The package allows design parameters (machine speeds, fiber volume fraction, tightness factor, etc.) to be easily obtained and the relationships between said parameters to be demonstrated graphically. The fabirc geometry model (FGM) method was adopted to evaluate the mechanical properties of the composites. Experimental evidence demonstrates the success of the use of dynamic models in the design software for the manufacture of braided fabric preforms.
Statistical Model of the 3-D Braided Composites Strength
Institute of Scientific and Technical Information of China (English)
XIAO Laiyuan; ZUO Weiwei; CAI Ganwei; LIAO Daoxun
2007-01-01
Based on the statistical model for the tensile statistical strength of unidirectional composite materials and the stress analysis of 3-D braided composites, a new method is proposed to calculate the tensile statistical strength of the 3-D braided composites. With this method, the strength of 3-D braided composites can be calculated with very large accuracy, and the statistical parameters of 3-D braided composites can be determined. The numerical result shows that the tensile statistical strength of 3-D braided composites can be predicted using this method.
Quantum Lorentz and braided Poincare groups
Zakrzewski, S.
1997-01-01
Quantum Lorentz groups H admitting quantum Minkowski space V are selected. Natural structure of a quantum space G = V x H is introduced, defining a quantum group structure on G only for triangular H (q=1). We show that it defines a braided quantum group structure on G for |q|=1.
Iadecola, Thomas; Schuster, Thomas; Chamon, Claudio
2016-08-01
Many topological phenomena first proposed and observed in the context of electrons in solids have recently found counterparts in photonic and acoustic systems. In this work, we demonstrate that non-Abelian Berry phases can arise when coherent states of light are injected into "topological guided modes" in specially fabricated photonic waveguide arrays. These modes are photonic analogues of topological zero modes in electronic systems. Light traveling inside spatially well-separated topological guided modes can be braided, leading to the accumulation of non-Abelian phases, which depend on the order in which the guided beams are wound around one another. Notably, these effects survive the limit of large photon occupation, and can thus also be understood as wave phenomena arising directly from Maxwell's equations, without resorting to the quantization of light. We propose an optical interference experiment as a direct probe of this non-Abelian braiding of light.
Burst Testing of Triaxial Braided Composite Tubes
Salem, J. A.; Bail, J. L.; Wilmoth, N. G.; Ghosn, L. J.; Kohlman, L. W.; Roberts, G. D.; Martin, R. E.
2014-01-01
Applications using triaxial braided composites are limited by the materials transverse strength which is determined by the delamination capacity of unconstrained, free-edge tows. However, structural applications such as cylindrical tubes can be designed to minimize free edge effects and thus the strength with and without edge stresses is relevant to the design process. The transverse strength of triaxial braided composites without edge effects was determined by internally pressurizing tubes. In the absence of edge effects, the axial and transverse strength were comparable. In addition, notched specimens, which minimize the effect of unconstrained tow ends, were tested in a variety of geometries. Although the commonly tested notch geometries exhibited similar axial and transverse net section failure strength, significant dependence on notch configuration was observed. In the absence of unconstrained tows, failure ensues as a result of bias tow rotation, splitting, and fracture at cross-over regions.
Braid group representation on quantum computation
Energy Technology Data Exchange (ETDEWEB)
Aziz, Ryan Kasyfil, E-mail: kasyfilryan@gmail.com [Department of Computational Sciences, Bandung Institute of Technology (Indonesia); Muchtadi-Alamsyah, Intan, E-mail: ntan@math.itb.ac.id [Algebra Research Group, Bandung Institute of Technology (Indonesia)
2015-09-30
There are many studies about topological representation of quantum computation recently. One of diagram representation of quantum computation is by using ZX-Calculus. In this paper we will make a diagrammatical scheme of Dense Coding. We also proved that ZX-Calculus diagram of maximally entangle state satisfies Yang-Baxter Equation and therefore, we can construct a Braid Group representation of set of maximally entangle state.
Geometric representations of the braid groups
Castel, Fabrice
2011-01-01
We show that the morphisms from the braid group with n strands in the mapping class group of a surface with a possible non empty boundary, assuming that its genus is smaller or equal to n/2 are either cyclic morphisms (their images are cyclic groups), or transvections of monodromy morphisms (up to multiplication by an element in the centralizer of the image, the image of a standard generator of the braid group is a Dehn twist, and the images of two consecutive standard generators are two Dehn twists along two curves intersecting in one point). As a corollary, we determine the endomorphisms, the injective endomorphisms, the automorphisms and the outer automorphism group of the following groups: the braid group with n strands where n is greater than or equal to 6, and the mapping class group of any surface of genus greater or equal than 2. For each statement involving the mapping class group, we study both cases: when the boundary is fixed pointwise, and when each boundary component is fixed setwise. We will al...
Creep Test of Polymer-matrix 3-D Braided Composites
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The long-term creep behavior of polymer-matrix 3-D braided composites was studied by using the tensile creep test method, and the effect of braiding structure, braiding angle and fiber volume fraction were discussed. The creep curve appears as expected, and can be defimed two phases,namely, the primary phase and the secondary phase. For each sample, strain increases with time rapidly, and then the strain rate decreases and appears to approach a constant rate of change (steady-state creep). The experiment results show that the creep resistant properties are improved while the braiding angle decreases or the fiber volume fraction increases, and that the five-directional braiding structure offers better creep resistant properties than the fourdirectional braiding structure.
Teleportation, Braid Group and Temperley--Lieb Algebra
Zhang, Yong
2006-01-01
We explore algebraic and topological structures underlying the quantum teleportation phenomena by applying the braid group and Temperley--Lieb algebra. We realize the braid teleportation configuration, teleportation swapping and virtual braid representation in the standard description of the teleportation. We devise diagrammatic rules for quantum circuits involving maximally entangled states and apply them to three sorts of descriptions of the teleportation: the transfer operator, quantum mea...
Institute of Scientific and Technical Information of China (English)
Xianghua LI; Xiaohui LIU; Shenfang YUAN
2008-01-01
The experimental characterization of three-dimensional (3-D) braided composites is extremely important for their design and analysis. Because of their desirable attributes and outstanding performance, optical fiber sensors (OFSs) can be embedded to mon-itor mechanical properties of textile composites. This paper discusses two techniques to incorporate different OFSs into 3-D braided composite preforms. The oper-ating principle of various sensor systems is first con-ducted. Experiments using Michelson interferometers, FBG sensors, and micro-bend sensors are performed to verify the concept of the proposed method. Strain curves of various OFSs tests are finally compared, and they all exhibit good linearity.
Validation of the physical modeling approach for braided rivers
Rosatti, Giorgio
2002-12-01
Laboratory channels are often used to study the complexity of braiding mechanisms for the advantages with respect to field studies. Nevertheless, the extensive use of experimental data raises the question of how representative laboratory braided channels are as compared to real braided rivers. This study verifies to what extent laboratory braided patterns reproduce the main features of braided rivers. Experimental data display isotropic and anisotropic scaling of braided patterns, state-space plot of total widths, anisotropic scaling of islands, and statistical distribution of island areas that are similar to those observed in real rivers. Moreover, the data reveals scaling in the perimeter-area relation. These results support both the reliability of experimental braided channels as physical models of braided rivers and also the possibility of investigating some aspects of braiding in the laboratory that are difficult to address in the field. The lack of preferential scales in island characteristics suggests that other phenomena must play a key role in generating island shapes besides classical sediment transport-based mechanisms which tend to select well-defined length scales.
CAD/CAM of braided preforms for advanced composites
Yang, Gui; Pastore, Christopher; Tsai, Yung Jia; Soebroto, Heru; Ko, Frank
A CAD/CAM system for braiding to produce preforms for advanced textile structural composites is presented in this paper. The CAD and CAM systems are illustrated in detail. The CAD system identifies the fiber placement and orientation needed to fabricate a braided structure over a mandrel, for subsequent composite formation. The CAM system uses the design parameters generated by the CAD system to control the braiding machine. Experimental evidence demonstrating the success of combining these two technologies to form a unified CAD/CAM system for the manufacture of braided fabric preforms with complex structural shapes is presented.
Braided Composite Technologies for Rotorcraft Structures
Jessie, Nathan
2015-01-01
A&P Technology has developed a braided material approach for fabricating lightweight, high-strength hybrid gears for aerospace drive systems. The conventional metallic web was replaced with a composite element made from A&P's quasi-isotropic braid. The 0deg, +/-60deg braid architecture was chosen so that inplane stiffness properties and strength would be nearly equal in all directions. The test results from the Phase I Small Spur Gear program demonstrated satisfactory endurance and strength while providing a 20 percent weight savings. (Greater weight savings is anticipated with structural optimization.) The hybrid gears were subjected to a proof-of-concept test of 1 billion cycles in a gearbox at 10,000 revolutions per minute and 490 in-lb torque with no detectable damage to the gears. After this test the maximum torque capability was also tested, and the static strength capability of the gears was 7x the maximum operating condition. Additional proof-of-concept tests are in progress using a higher oil temperature, and a loss-of-oil test is planned. The success of Phase I led to a Phase II program to develop, fabricate, and optimize full-scale gears, specifically Bull Gears. The design of these Bull Gears will be refined using topology optimization, and the full-scale Bull Gears will be tested in a full-scale gear rig. The testing will quantify benefits of weight savings, as well as noise and vibration reduction. The expectation is that vibration and noise will be reduced through the introduction of composite material in the vibration transmission path between the contacting gear teeth and the shaft-and-bearing system.
The Pure Virtual Braid Group Is Quadratic
Lee, Peter
2011-01-01
If an augmented algebra K over Q is filtered by powers of its augmentation ideal I, the associated graded algebra gr_I K need not in general be quadratic: although it is generated in degree 1, its relations may not be generated by homogeneous relations of degree 2. In this paper we give a criterion which is equivalent to gr_I K being quadratic. We apply this criterion to the group algebra of the pure virtual braid group (also known as the quasi-triangular group), and show that the corresponding associated graded algebra is quadratic.
Unraveling "Braid": Puzzle Games and Storytelling in the Imperative Mood
Arnott, Luke
2012-01-01
"Unraveling Braid" analyzes how unconventional, non-linear narrative fiction can help explain the ways in which video games signify. Specifically, this essay looks at the links between the semiotic features of Jonathan Blow's 2008 puzzle-platform video game Braid and similar elements in Georges Perec's 1978 novel "Life A User's Manual," as well as…
Sharing the Arts of the Blue Ridge Mountains. Rug Braiding.
Holman, Martha; Gailey, Lamar
This module on rug braiding is one of eight modules designed to provide instruction on authentic Blue Ridge Mountain crafts to adult basic education students at low cost. Contents include notes on the history of rug braiding; process used, including equipment and materials, as well as method described narratively and graphically; and the followup,…
Braids as a representation space of SU(5)
Cartin, Daniel
2015-01-01
The Standard Model of particle physics provides very accurate predictions of phenomena occurring at the sub-atomic level, but the reason for the choice of symmetry group and the large number of particles considered elementary, is still unknown. Along the lines of previous preon models positing a substructure to explain these aspects, Bilson-Thompson showed how the first family of elementary particles is realized as the crossings of braids made of three strands, with charges resulting from twists of those strands with certain conditions; in this topological model, there are only two distinct neutrino states. Modeling the particles as braids implies these braids must be the representation space of a Lie algebra, giving the symmetries of the Standard Model. In this paper, this representation is made explicit, obtaining the raising operators associated with the Lie algebra of $SU(5)$, one of the earliest grand unified theories. Because the braids form a group, the action of these operators are braids themselves, ...
Approaches for Tensile Testing of Braided Composites
Roberts, Gary D.; Salem, Jonathan A.; Bail, Justin L.; Kohlman, Lee W.; Binienda, Wieslaw K.; Martin, Richard E.
2011-01-01
For angleply composites, lamina tension and compression strengths are commonly determined by applying classical lamination theory to test data obtained from testing of angleply composite specimens. For textile composites such as 2D triaxial braids, analysis is more complex and standard test methods do not always yield reliable strength measurements. This paper describes recent research focused on development of more reliable tensile test methods for braided composites and presents preliminary data for various approaches. The materials investigated in this work have 0deg+/-60 2D triaxial braid architecture with nearly equal fiber volume fraction in each of the three fiber directions. Flat composite panels are fabricated by resin transfer molding (RTM) using six layers of the braided preform aligned along the 0deg fiber direction. Various epoxy resins are used as matrix materials. Single layer panels are also fabricated in order to examine local variations in deformation related to the braid architecture. Specimens are cut from these panels in the shape of standard straight-sided coupons, an alternative bowtie geometry, and an alternative notched geometry. Axial tensile properties are measured using specimens loaded along the 0deg fiber direction. Transverse tensile properties are measured using specimens loaded perpendicular to the 0deg fibers. Composite tubes are also fabricated by RTM. These tubes are tested by internal pressurization using a soft rubbery material sealed between the inside diameter of the tube and the load fixtures. The ends of the tube are unconstrained, so the primary load is in the hoop direction. Tubes are fabricated with the 0deg fibers aligned along the tube axis by overbraiding the preform on a mandrel. Since the loading is in the hoop direction, testing of the overbraided tube provides a measure of transverse tensile strength. Previous work has indicated that straight-sided coupons yield a transverse tensile strength that is much lower
The braidings of mapping class groups and loop spaces
Song, Yongjin
2000-01-01
The disjoint union of mapping class groups forms a braided monoidal category. We give an explicit expression of braidings in terms of both their actions on the fundamental group of the surface and the standard Dehn twists. This braided monoidal category gives rise to a double loop space. We prove that the action of little 2-cube operad does not extend to the action of little 3-cube operad by showing that the Browder operation induced by 2-cube operad action is nontrivial. A rather simple expr...
Core reilforced braided composite armour as a substitute to steel in concrete reinforcement
Fangueiro, Raúl; Sousa, Guilherme José Miranda de; Araújo, Mário Duarte de; Pereira, C. Gonilho; Jalali, Said
2006-01-01
This paper presents the work that is being done at the University of Minho concerning the development of brainded rods concrete reinforcement. Several samples of core reinforced braided fabrics have been produced varying the type of braided fabric (core reinforced and hybrid), the linear density of the core reinforcing yarns and the type of braiding structure (with or without ribs). The tensile properties of braided fabrics has also been analysed. Core reinforced braided composites rods were ...
Failure analysis of woven and braided fabric reinforced composites
Naik, Rajiv A.
1994-01-01
A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.
Vassiliev invariants; 1, braid groups and rational homotopy theory
Funar, L
1995-01-01
We get a detailed account of Vassiliev type invariants starting with Chen's theory of iterated integrals and Malcev's completion of discrete groups. The canonical injection of the group of pure braids into its completion is identified with the universal Kontsevich-Vassiliev invariant.Further we discuss the extension of this morphism to the whole braid group and the multiplication law for the last one.
Self-Sustained Magnetic Braiding in Toroidal Plasmas
Itoh, K; Fukuyama, A.; Itoh, S.-I.; Yagi, M.; Azumi, M.
1994-01-01
Theory for the magnetic braiding in toroidal plasmas, which is caused by microscopic pressure-gradient-driven turbulence, is developed. When the pressure gradient exceeds a threshold, the self-sustaining of the magnetic braiding and enhanced anomalous transport occur. The balance between the nonlinear destabilization and nonlinear stabilization, which determines the stationary turbulence, is solved analytically for the case of interchange mode. The enhanced thermal conductivity and magneti...
Multifunctional braided composite rods for civil engineering applications
Fangueiro, Raúl; Zdraveva, Emilijia; Pereira, Cristiana Gonilho; Lanceros-Méndez, S.; Jalali, Said; Araújo, Mário Duarte de
2010-01-01
This paper presents the development of a braided reinforced composite rod (BCR) able to both reinforce and monitor the stress state of concrete elements. Carbon fibers have been used as sensing and reinforcing material along with glass fiber. Various composites rods have been produced using an author patented technique based on a modified conventional braiding machine. The materials investigated were prepared with different carbon fiber content as follows: BCR2 (77% glass/23% c...
Braids as a representation space of SU(5)
Energy Technology Data Exchange (ETDEWEB)
Cartin, Daniel, E-mail: cartin@naps.edu [Naval Academy Preparatory School, 440 Meyerkord Avenue, Newport, Rhode Island 02841-1519 (United States)
2015-06-15
The standard model of particle physics provides very accurate predictions of phenomena occurring at the sub-atomic level, but the reason for the choice of symmetry group and the large number of particles considered elementary is still unknown. Along the lines of previous preon models positing a substructure to explain these aspects, Bilson-Thompson showed how the first family of elementary particles is realized as the crossings of braids made of three strands, with charges resulting from twists of those strands with certain conditions; in this topological model, there are only two distinct neutrino states. Modeling the particles as braids implies these braids must be the representation space of a Lie algebra, giving the symmetries of the standard model. In this paper, this representation is made explicit, obtaining the raising operators associated with the Lie algebra of SU(5), one of the earliest grand unified theories. Because the braids form a group, the action of these operators are braids themselves, leading to their identification as gauge bosons. Possible choices for the other two families are also given. Although this realization of particles as braids is lacking a dynamical framework, it is very suggestive, especially when considered as a natural method of adding matter to loop quantum gravity.
Braids as a representation space of SU(5)
Cartin, Daniel
2015-06-01
The standard model of particle physics provides very accurate predictions of phenomena occurring at the sub-atomic level, but the reason for the choice of symmetry group and the large number of particles considered elementary is still unknown. Along the lines of previous preon models positing a substructure to explain these aspects, Bilson-Thompson showed how the first family of elementary particles is realized as the crossings of braids made of three strands, with charges resulting from twists of those strands with certain conditions; in this topological model, there are only two distinct neutrino states. Modeling the particles as braids implies these braids must be the representation space of a Lie algebra, giving the symmetries of the standard model. In this paper, this representation is made explicit, obtaining the raising operators associated with the Lie algebra of SU(5), one of the earliest grand unified theories. Because the braids form a group, the action of these operators are braids themselves, leading to their identification as gauge bosons. Possible choices for the other two families are also given. Although this realization of particles as braids is lacking a dynamical framework, it is very suggestive, especially when considered as a natural method of adding matter to loop quantum gravity.
Analysis of woven and braided fabric reinforced composites
Naik, Rajiv A.
1994-01-01
A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell, was developed to predict overall, three dimensional, thermal and mechanical properties. This analytical technique was implemented in a user-friendly, personal computer-based, windows compatible code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain, 5-harness satin, and 8-harness satin weave composites along with 2-D braided and 2x2, 2-D triaxial braided composites. The calculated overall stiffnesses correlated well with available 3-D finite element results and test data for both the woven and the braided composites. Parametric studies were performed to investigate the effects of yarn size on the yarn crimp and the overall thermal and mechanical constants for plain weave composites. The effects of braid angle were investigated for the 2-D braided composites. Finally, the effects of fiber volume fraction on the yarn undulations and the thermal and mechanical properties of 2x2, 2-D triaxial braided composites were also investigated.
Braids as a representation space of SU(5)
International Nuclear Information System (INIS)
The standard model of particle physics provides very accurate predictions of phenomena occurring at the sub-atomic level, but the reason for the choice of symmetry group and the large number of particles considered elementary is still unknown. Along the lines of previous preon models positing a substructure to explain these aspects, Bilson-Thompson showed how the first family of elementary particles is realized as the crossings of braids made of three strands, with charges resulting from twists of those strands with certain conditions; in this topological model, there are only two distinct neutrino states. Modeling the particles as braids implies these braids must be the representation space of a Lie algebra, giving the symmetries of the standard model. In this paper, this representation is made explicit, obtaining the raising operators associated with the Lie algebra of SU(5), one of the earliest grand unified theories. Because the braids form a group, the action of these operators are braids themselves, leading to their identification as gauge bosons. Possible choices for the other two families are also given. Although this realization of particles as braids is lacking a dynamical framework, it is very suggestive, especially when considered as a natural method of adding matter to loop quantum gravity
A Categorical Model for the Virtual Braid Group
Kauffman, Louis H
2011-01-01
This paper gives a new interpretation of the virtual braid group in terms of a tensor category with generating diagrams that are abstract strings or connections between pairs of strands in an identity braid, and elements corresponding to virtual crossings that generate the symmetric group. The point of this categorical formulation of the virtual braid groups is that we see how these groups form a natural extension of the symmetric groups by formal elements that satisfy the algebraic Yang-Baxter equation. The category we desribe is a natural structure for an algebraist interested in exploring formal properties of the algebraic Yang-Baxter equation, and it is directly related to more topological points of view about virtual links and virtual braids. We discuss a generalization of the virtual braiding formalism to braided tensor categories that can be used for obtaining invariants of knots and links via Hopf algebras. The invariants we obtain are invariants of rotational virtual knots and links, where the term r...
Topology and geometry of nematic braids
Energy Technology Data Exchange (ETDEWEB)
Čopar, Simon, E-mail: simon.copar@fmf.uni-lj.si
2014-05-01
Topological analysis of disclinations in nematic liquid crystals is an interesting and diverse topic that goes from strict mathematical theorems to applications in elaborate systems found in experiments and numerical simulations. The theory of nematic disclinations is shown from both the geometric and topological perspectives. Entangled disclination line networks are analyzed based on their shape and the behavior of their cross section. Methods of differential geometry are applied to derive topological results from reduced geometric information. For nematic braids, systems of −1/2 disclination loops, created by inclusion of homeotropic colloidal particles, a formalism of rewiring is constructed, allowing comparison and construction of an entire set of different conformations. The disclination lines are described as ribbons and a new topological invariant, the self-linking number, is introduced. The analysis is generalized from a constant −1/2 profile to general profile variations, while retaining the geometric treatment. The workings of presented topological statements are demonstrated on simple models of entangled nematic colloids, estimating the margins of theoretical assumptions made in the formal derivations, and reviewing the behavior of the disclinations not only under topological, but also under free-energy driven constraints.
EXPERIMENTS OF THREE-DIMENSIONAL FLOW STRUCTURE IN BRAIDED RIVERS
Institute of Scientific and Technical Information of China (English)
HUA Zu-lin; GU Li; CHU Ke-jian
2009-01-01
The braided river is a typical river pattern in nature, but there is a paucity of comprehensive data set describing the three-dimensional flow field in the braided river. A physical model experiment was used to study the flow characteristics in the typical braided river with a mid-bar between two anabranches. In the experiment, two kinds of mid-bar with the ratios of its length to maximal width of 3 and 5 were considered. Moreover, the mid-bar could be moved to adjust the width of two anabranches. The detailed measurements of velocity were conducted using an acoustic Doppler velocimeter over a grid defined throughout the whole braided river region, including the bifurcation, two anabranches and the confluence. In two kinds of mid-bar braided models, a separation zone was observed in the anabranch of the model in which the ratio of length to maximal width of mid-bar is 3, however the separation zone was not found in another model in which the ratio is 5. In addition, the opposite secondary cells were observed at the bend apex of anabranch in two models, and different longitudinal velocity distributions in the entrance region of anabranch account for this opposite flow structure. Finally, turbulent kinetic energy were shown and compared in different situations. The high turbulence occurs at the place with strong shear, especially at the boundary of the separation zone and the high velocity passing flow.
Virtual optimization of self-expandable braided wire stents.
De Beule, Matthieu; Van Cauter, Sofie; Mortier, Peter; Van Loo, Denis; Van Impe, Rudy; Verdonck, Pascal; Verhegghe, Benedict
2009-05-01
At present, the deployment of self-expandable braided stents has become a common and widely used minimally invasive treatment for stenotic lesions in the cardiovascular, gastrointestinal and respiratory system. To improve these revascularization procedures (e.g. increase the positioning accuracy) the optimal strategy lies in the further development of the stent design. In the context of optimizing braided stent designs, computational models can provide an excellent research tool complementary to analytical models. In this study, a finite element based modelling strategy is proposed to investigate and optimize the mechanics of braided stents. First a geometrical and finite element model of a braided Urolume endoprosthesis was built with the open source pyFormex design tool. The results of the reference simulation of the Urolume stent are in close agreement with both analytical and experimental data. Subsequently, a simplex-based design optimization algorithm automatically adjusts the reference Urolume geometry to facilitate precise positioning by reducing the foreshortening with 20% while maintaining the radial stiffness. Therefore, the proposed modelling strategy appears to be a promising optimization methodology in braided stent design.
On M\\"{u}ger's centralizer for a certain class of braided fusion categories
Burciu, S.
2014-01-01
We provide a general formula for Mueger's centralizer of any fusion subcategory of a braided fusion category containing a tannakian subcategory. This entails a description for Mueger's centralizer of all fusion subcategories of a group theoretical braided fusion category.
The braided single-stage protocol for quantum secure communication
Darunkar, Bhagyashri; Verma, Pramode K.
2014-05-01
This paper presents the concept and implementation of a Braided Single-stage Protocol for quantum secure communication. The braided single-stage protocol is a multi-photon tolerant secure protocol. This multi-photon tolerant protocol has been implemented in the laboratory using free-space optics technology. The proposed protocol capitalizes on strengths of the three-stage protocol and extends it with a new concept of braiding. This protocol overcomes the limitations associated with the three-stage protocol in the following ways: It uses the transmission channel only once as opposed to three times in the three-stage protocol, and it is invulnerable to man-in-the-middle attack. This paper also presents the error analysis resulting from the misalignment of the devices in the implementation. The experimental results validate the efficient use of transmission resources and improvement in the data transfer rate.
Teleportation, braid group and Temperley-Lieb algebra
International Nuclear Information System (INIS)
We explore algebraic and topological structures underlying the quantum teleportation phenomena by applying the braid group and Temperley-Lieb algebra. We realize the braid teleportation configuration, teleportation swapping and virtual braid representation in the standard description of the teleportation. We devise diagrammatic rules for quantum circuits involving maximally entangled states and apply them to three sorts of descriptions of the teleportation: the transfer operator, quantum measurements and characteristic equations, and further propose the Temperley-Lieb algebra under local unitary transformations to be a mathematical structure underlying the teleportation. We compare our diagrammatical approach with two known recipes to the quantum information flow: the teleportation topology and strongly compact closed category, in order to explain our diagrammatic rules to be a natural diagrammatic language for the teleportation
Mechanical properties of braided commingled glass/polypropylene composites
International Nuclear Information System (INIS)
Fibre reinforced plastics (Fr) are now widely used due to improved specific properties compared to more conventional materials. In particular the automotive and aerospace industries are turning towards these materials for weight reduction. Moreover the anti corrosion properties of FRP are also of interest to manufacturers as an alternative to metallic materials. The reinforcing fibres used in the composite materials can be assembled using a variety of textile processing techniques. Of these, 2-D braiding is particularly attractive for hollow components or sandwich laminates. In this study flat plaques were produced by braiding commingled yam at various angles on a cylindrical mandrel, after which the braids were slit and consolidated by non-isothermal compression moulding. Mechanical properties of the composites were measured and the results are discussed with reference to the arising fibre architecture and microstructure. The results obtained illustrate that there is a major influence of the fibre orientation on the final properties of the composite. (author)
A braided monoidal category for free super-bosons
Runkel, Ingo
2012-01-01
The chiral conformal field theory of free super-bosons is generated by weight one currents whose mode algebra is the affinisation of an abelian Lie super-algebra h with non-degenerate super-symmetric pairing. The mode algebras of a single free boson and of a single pair of symplectic fermions arise for even|odd dimension 1|0 and 0|2 of h, respectively. In this paper, the representations of the untwisted mode algebra of free super-bosons are equipped with a tensor product, a braiding, and an associator. In the symplectic fermion case, i.e. if h is purely odd, the braided monoidal structure is extended to representations of the Z/2Z-twisted mode algebra. The tensor product is obtained by computing spaces of vertex operators. The braiding and associator are determined by explicit calculations from three- and four-point conformal blocks.
Feasibility evaluation of the monolithic braided ablative nozzle
Director, Mark N.; McPherson, Douglass J., Sr.
1992-02-01
The feasibility of the monolithic braided ablative nozzle was evaluated as part of an independent research and development (IR&D) program complementary to the National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC) Low-Cost, High-Reliability Case, Insulation and Nozzle for Large Solid Rocket Motors (LOCCIN) Program. The monolithic braided ablative nozzle is a new concept that utilizes a continuous, ablative, monolithic flame surface that extends from the nozzle entrance, through the throat, to the exit plane. The flame surface is fabricated using a Through-the-Thickness braided carbon-fiber preform, which is impregnated with a phenolic or phenolic-like resin. During operation, the braided-carbon fiber/resin material ablates, leaving the structural backside at temperatures which are sufficiently low to preclude the need for any additional insulative materials. The monolithic braided nozzle derives its potential for low life cycle cost through the use of automated processing, one-component fabrication, low material scrap, low process scrap, inexpensive raw materials, and simplified case attachment. It also has the potential for high reliability because its construction prevents delamination, has no nozzle bondlines or leak paths along the flame surface, is amenable to simplified analysis, and is readily inspectable. In addition, the braided construction has inherent toughness and is damage-tolerant. Two static-firing tests were conducted using subscale, 1.8 - 2.0-inch throat diameter, hardware. Tests were approximately 15 seconds in duration, using a conventional 18 percent aluminum/ammonium perchlorate propellant. The first of these tests evaluated the braided ablative as an integral backside insulator and exit cone; the second test evaluated the monolithic braided ablative as an integral entrance/throat/exit cone nozzle. Both tests met their objectives. Radial ablation rates at the throat were as predicted, approximately 0.017 in
International Nuclear Information System (INIS)
Dual mechanical braiding experiments provide a useful tool with which to investigate the nature of interactions between rod-like molecules, for instance actin and DNA. In conditions close to molecular condensation, one would expect an appearance of a local minimum in the interaction potential between the two molecules. We investigate this situation, introducing an attractive component into the interaction potential, using a model developed for describing such experiments. We consider both attractive interactions that do not depend on molecular structure and those which depend on a DNA-like helix structure. In braiding experiments, an attractive term may lead to certain effects. A local minimum may cause molecules to collapse from a loosely braided configuration into a tight one, occurring at a critical value of the moment applied about the axis of the braid. For a fixed number of braid pitches, this may lead to coexistence between the two braiding states, tight and loose. Coexistence implies certain proportions of the braid are in each state, their relative size depending on the number of braid pitches. This manifests itself as a linear dependence in numerically calculated quantities as functions of the number of braid pitches. Also, in the collapsed state, the braid radius stays roughly constant. Furthermore, if the attractive interaction is helix dependent, the left-right handed braid symmetry is broken. For a DNA like charge distribution, using the Kornyshev–Leikin interaction model, our results suggest that significant braid collapse and coexistence only occurs for left handed braids. Regardless of the interaction model, the study highlights the possible qualitative physics of braid collapse and coexistence; and the role helix specific forces might play, if important. The model could be used to connect other microscopic theories of interaction with braiding experiments. (paper)
Investigation on the Thermal Conductivity of 3-Dimensional and 4-Directional Braided Composites
Institute of Scientific and Technical Information of China (English)
Liu Zhenguo; Zhang Haiguo; Lu Zixing; Li Diansen
2007-01-01
It is vital to choose a factual and reasonable micro-structural model of braided composites for improving the calculating precision of thermal property of 3-D braided composites by finite element method (FEM). On the basis of new microstructure model of braided composites proposed recently, the model of FEM calculation for thermal conductivity of 3-dimennsional and 4-directional braided composites is set up in this paper. The curves of coefficient of effective thermal conductivity versus fiber volume ratio and interior braiding angle are obtained. Furthermore, comparing the results of FEM with the available experimental data, the reasonability and veracity of calculation are confirmed at the same time.
Relationship Between Compression Strength and Its Microstructure of 5 Axial-Braided Composite
Institute of Scientific and Technical Information of China (English)
Yang; Chaokun; Zhu; Jianxun; Jiang; Yun
2007-01-01
Compression performance of 5-axial braided composites is observed through compression tests.A mixed model of micro-buckling shear with braided tows web is set up to predict compression stress of braided composite through analyzing three broken modes.Using this mixed model,data from tests indicated that the main parameters effecting the compression properties of braided composite are fiber volume fraction,directional angle,axial-tow volume fraction and diameter of tow.Contributing rate of tows is proposed to describe the compression properties of fibre composites.Optimization geometrical structure of braids can optimize composite properties.
Mechanical Properties of Triaxial Braided Carbon/Epoxy Composites
Bowman, C. L.; Roberts, G. D.; Braley, M. S.; Xie, M.; Booker, M. J.
2003-01-01
In an on-going effort to increase the safety and efficiency of turbine engines, the National Aeronautics and Space Administration is exploring lightweight alternatives to the metal containment structures that currently encase commercial jet engines. Epoxy reinforced with braided carbon fibers is a candidate structural material which may be suitable for an engine case. This paper reports flat-coupon mechanical-property experiments performed to compliment previously reported subcomponent impact testing and analytical simulation of containment structures. Triaxial-braid T700/5208 epoxy and triaxial-braid T700h436 toughened epoxy composites were evaluated. Also, two triaxial-braid architectures (0 degrees plus or minus 60 degrees, and 0 degrees plus or minus 45 degrees) with the M36 resin were evaluated through tension, compression, and shear testing. Tensile behavior was compared between standard straight-sided specimens (ASTM D3039) and bow-tie specimens. Both double-notch shear (ASTM D3846) and Iosepescu (ASTM D5379) tests were performed as well. The M36/O degrees plus or minus 45 degrees configuration yield the best response when measurements were made parallel to the axial tows. Conversely, the M36/0 degrees plus or minus 60 degrees configuration was best when measurements were made perpendicular to the axial tows. The results were used to identify critical properties and to augment the analysis of impact experiments.
The braid index of complicated DNA polyhedral links.
Directory of Open Access Journals (Sweden)
Xiao-Sheng Cheng
Full Text Available The goal of this paper is to determine the braid index of two types of complicated DNA polyhedral links introduced by chemists and biologists in recent years. We shall study it in a more broad context and actually consider so-called Jaeger's links (more general Traldi's links which contain, as special cases, both four types of simple polyhedral links whose braid indexes have been determined and the above two types of complicated DNA polyhedral links. Denote by b(L and c(L the braid index and crossing number of an oriented link L, respectively. Roughly speaking, in this paper, we prove that b(L = c(L/2 + 1 for any link L in a family including Jaeger's links and contained in Traldi's links, which is obtained by combining the MFW inequality and an Ohyama's result on upper bound of the braid index. Our result may be used to to characterize and analyze the structure and complexity of DNA polyhedra and entanglement in biopolymers.
Processing and performance of nanophased braided carbon/epoxy composites
International Nuclear Information System (INIS)
A systematic study has been carried out to investigate mechanical properties of 2D nanophased braided carbon/epoxy composites. SC-15 epoxy with three types of braided fabrics: ±45 deg., 0/±45 deg., and 0/±60 deg. was used to fabricate composite laminates using vacuum assisted resin infusion molding (VARIM) process. Low-velocity impact (LVI), ultrasonic nondestructive evaluation (NDE) and 3-point bend flexure studies were carried out on biaxial and triaxial braided samples. Impact parameters like peak load and absorbed energy were calculated. All the LVI tested samples were then subjected to ultrasonic c-scan testing to determine the damage size. From the results it was seen that laminates sustained the impact load without any damage at 10 J, a little damage at 20 J and more damage at 30 J. From the ultrasonic tests it was seen that the biaxial ±45 deg. laminates had lowest damage. Flexural test showed the highest flexural strength and stiffness for triaxial 0 deg./±45 deg. An investigation was also carried out to improve the properties of the braided laminates by introducing Nanomer I-28E nanoclay, a surface modified montmorillonite mineral, into SC-15 epoxy matrix. Different weight percentages of nanoclay were dispersed in SC-15 epoxy. Highest properties were obtained for samples with 1% by weight of nanoclay reinforcement.
Processing and performance of nanophased braided carbon/epoxy composites
Energy Technology Data Exchange (ETDEWEB)
Hosur, Mahesh V., E-mail: hosur@tuskegee.ed [Center for Advanced Materials, Tuskegee University, Tuskegee, AL 36088 (United States); Islam, Md. Mazedul; Jeelani, Shaik [Center for Advanced Materials, Tuskegee University, Tuskegee, AL 36088 (United States)
2010-04-15
A systematic study has been carried out to investigate mechanical properties of 2D nanophased braided carbon/epoxy composites. SC-15 epoxy with three types of braided fabrics: +-45 deg., 0/+-45 deg., and 0/+-60 deg. was used to fabricate composite laminates using vacuum assisted resin infusion molding (VARIM) process. Low-velocity impact (LVI), ultrasonic nondestructive evaluation (NDE) and 3-point bend flexure studies were carried out on biaxial and triaxial braided samples. Impact parameters like peak load and absorbed energy were calculated. All the LVI tested samples were then subjected to ultrasonic c-scan testing to determine the damage size. From the results it was seen that laminates sustained the impact load without any damage at 10 J, a little damage at 20 J and more damage at 30 J. From the ultrasonic tests it was seen that the biaxial +-45 deg. laminates had lowest damage. Flexural test showed the highest flexural strength and stiffness for triaxial 0 deg./+-45 deg. An investigation was also carried out to improve the properties of the braided laminates by introducing Nanomer I-28E nanoclay, a surface modified montmorillonite mineral, into SC-15 epoxy matrix. Different weight percentages of nanoclay were dispersed in SC-15 epoxy. Highest properties were obtained for samples with 1% by weight of nanoclay reinforcement.
Nonlinear Deformation Behavior of New Braided Composites with Six-axis Yarn Orientations
International Nuclear Information System (INIS)
The braiding technology is one of fabrication methods that can produce three-dimensional fiber preforms. Braided composites have many advantages over other two-dimensional composites such as no delamination, high impact and fatigue properties, near-net shape preform, etc. Due to the undulated yarns in the braided preforms, however, their axial stiffness is lower than that of uni-directional or woven composites. To improve the axial stiffness, the longitudinal axial yarns were already introduced along with the braiding axis (five-axis braiding technology). In this study, we developed a new braided structure using six-axis braiding technology. In addition to braiding and longitudinal axial yarns, transverse axial yarn was introduced. New braided composites, so called six-axis braiding composites, were manufactured using ultra high molecular weight polyethylene and epoxy resin and their mechanical properties were characterized. To investigate the mechanical performance of these braided composites according to their manufacturing conditions, a numerical analysis was performed using their unit-cell modeling and finite element analysis. In the analysis the nonlinear deformation behavior will be included.
Quantized Affine Lie Algebras and Diagonalization of Braid Generators
Gould, M D; Gould, Mark D.; Zhang, Yao-Zhong
1994-01-01
Let $U_q(\\hat{\\cal G})$ be a quantized affine Lie algebra. It is proven that the universal R-matrix $R$ of $U_q(\\hat{\\cal G})$ satisfies the celebrated conjugation relation $R^\\dagger=TR$ with $T$ the usual twist map. As applications, braid generators are shown to be diagonalizable on arbitrary tensor product modules of integrable irreducible highest weight $U_q(\\hat{\\cal G})$-module and a spectral decomposition formula for the braid generators is obtained which is the generalization of Reshetikhin's and Gould's forms to the present affine case. Casimir invariants are constructed and their eigenvalues computed by means of the spectral decomposition formula. As a by-product, an interesting identity is found.
Changes of the hydrodynamic conditions in the braided river
Directory of Open Access Journals (Sweden)
Karol PLESIŃSKI
2014-11-01
Full Text Available The paper focuses on the understanding of the basic hydrodynamic conditions along the braided gravel-bed river. The measuring cross-section was located in the Ochotnica River, where its braided channel development was observed. Investigations take place from 2003 up to 2014. Measurements were performed for selected characteristic points. The study focused mostly on the measurements of water velocities under different flow conditions, and next on finding basic hydraulic parameters of flow: shear velocity, shear stresses, Reynolds number, Froude number. In addition, the gravel material from the river bed was examined, in order to find sedimentological characteristics of it.
Modeling of Moisture Diffusion in Carbon Braided Composites
Directory of Open Access Journals (Sweden)
S. Laurenzi
2008-01-01
Full Text Available In this study, we develop a methodology based on finite element analysis to predict the weight gain of carbon braided composite materials exposed to moisture. The analysis was based on the analogy between thermal conduction and diffusion processes, which allowed for a commercial code for finite element analysis to be used. A detailed finite element model using a repetitive unit cell (RUC was developed both for bundle and carbon braided composites. Conditioning tests were performed to estimate the diffusivity of both the resin and composite. When comparing numerical and experimental results, it was observed that the procedure introduces an average error of 20% and a maximum error of 31% if the RUC is assumed to be isotropic. On the other hand, the average error does not exceed 10% and the maximum error is less than 20% when the material is considered as orthotropic. The procedure is independent of the particular fiber architecture and can be extended to other composites.
Duality Theorem and Drinfeld Double in Braided Tensor Categories
Institute of Scientific and Technical Information of China (English)
Shouchuan Zhang
2003-01-01
Let (C, ( ), I, C) be a braided tensor category. For a finite Hopf algebra H in c with CH, H = C-1 H,H, the duality theorem is shown, i.e.,(R#H)#H^* ≌ R( ) (H-( )H^*)as algebras in C. Also, it is proved that the Drinfeld double (D(H), [b]) is a quasi-triangular Hopf algebra in c.
Electron beam processing of carbon fibre reinforced braided composites beams
International Nuclear Information System (INIS)
Complete text of publication follows. In this paper the possibility of producing a new type carbon fiber reinforced composite is examined by applying braiding, a well-known process of textile technology. The appearance of the new Hungarian carbon fiber with excellent mechanical properties in the market enables the development of newer type carbon fiber reinforced composites in the continuously widening range of engineering applications. Advanced hollow profiles, pipes and other composite products can be manufactured in continuous operation. A new way of composite production of this kind is the manufacturing of reinforcing structure by braiding technology producing a composite with sufficient mechanical properties from this cross directional fabric-like textile structure by impregnation. This manufacturing process can complete the variety of hollow products serving the same purpose as pultrusion or filament winding. This way a profile type framework element with a hollow cross section is manufactured having favorable mechanical properties. Owing to its small mass and high specific strength this product can be applied in dynamically loaded structures e.g. in the automotive industry. For crosslinking of the matrix the method of high-speed electron beam curing has been examined in order to reach continuous operation. The field of use and application of carbon fiber braided structures has a great chance especially in machine engineering and in the automotive industry. The main reason for this is that braiding processes are capable of producing structures having good mechanical properties at a low processing price. The mass of the composite load-bearing structure produced this way is one fifth of the steel product having similar geometry, and its specific mechanical properties are nearly as good as that of the most commonly applied semiproduct and structural component, the welded steel profile
Simulation of braiding anyons using matrix product states
Ayeni, Babatunde M.; Singh, Sukhwinder; Pfeifer, Robert N. C.; Brennen, Gavin K.
2016-04-01
Anyons exist as pointlike particles in two dimensions and carry braid statistics, which enable interactions that are independent of the distance between the particles. Except for a relatively few number of models, which are analytically tractable, much of the physics of anyons remains still unexplored. In this paper, we show how U(1) symmetry can be combined with the previously proposed anyonic matrix product states to simulate ground states and dynamics of anyonic systems on a lattice at any rational particle number density. We provide proof of principle by studying itinerant anyons on a one-dimensional chain where no natural notion of braiding arises and also on a two-leg ladder where the anyons hop between sites and possibly braid. We compare the result of the ground-state energies of Fibonacci anyons against hardcore bosons and spinless fermions. In addition, we report the entanglement entropies of the ground states of interacting Fibonacci anyons on a fully filled two-leg ladder at different interaction strength, identifying gapped or gapless points in the parameter space. As an outlook, our approach can also prove useful in studying the time dynamics of a finite number of non-Abelian anyons on a finite two-dimensional lattice.
Characterization of Triaxial Braided Composite Material Properties for Impact Simulation
Roberts, Gary D.; Goldberg, Robert K.; Biniendak, Wieslaw K.; Arnold, William A.; Littell, Justin D.; Kohlman, Lee W.
2009-01-01
The reliability of impact simulations for aircraft components made with triaxial braided carbon fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Improvements to standard quasi-static test methods are needed to account for the large unit cell size and localized damage within the unit cell. The deformation and damage of a triaxial braided composite material was examined using standard quasi-static in-plane tension, compression, and shear tests. Some modifications to standard test specimen geometries are suggested, and methods for measuring the local strain at the onset of failure within the braid unit cell are presented. Deformation and damage at higher strain rates is examined using ballistic impact tests on 61- by 61- by 3.2-mm (24- by 24- by 0.125-in.) composite panels. Digital image correlation techniques were used to examine full-field deformation and damage during both quasi-static and impact tests. An impact analysis method is presented that utilizes both local and global deformation and failure information from the quasi-static tests as input for impact simulations. Improvements that are needed in test and analysis methods for better predictive capability are examined.
Development of braided drug-loaded nanofiber sutures
Energy Technology Data Exchange (ETDEWEB)
Hu Wen [School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Huang Zhengming [School of Aerospace Engineering and Applied Mechanics, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Liu Xiangyang, E-mail: huangzm@tongji.edu.cn [Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 (Singapore)
2010-08-06
The objectives of this work are twofold. Firstly, while most work on electrospinning is limited to the development of only functional materials, a structural application of electrospun nanofibers is explored. Secondly, a drug-loaded tissue suture is fabricated and its various properties are characterized. Braided drug-loaded nanofiber sutures are obtained by combining an electrospinning process with a braiding technique followed by a coating procedure. Two different electrospinning techniques, i.e. blend and coaxial electrospinning, to incorporate a model drug cefotaxime sodium (CFX-Na) into poly(L-lactic acid) (PLLA) nanofibers have been applied and compared with each other. Properties of the braided drug-loaded sutures are characterized through a variety of methods including SEM, TEM and tensile testing. The results show that the nanofibers had a preferable micromorphology. The drug was incorporated into the polymer nanofibers homogeneously, with no cross-linking. The nanofibers maintained their fibrous structures. An in vitro release study indicates that the drug-loaded nanofibers fabricated by blend electrospinning and coaxial electrospinning had a different drug release behavior. An inhibition zone experiment shows that both sutures obtained from the nanofibers of the different electrospinning techniques had favorable antibacterial properties. The drug-loaded sutures had preferable histological compatibility performance compared with commercial silk sutures in an in vivo comparative study.
DETERMINATION OF INTERNAL STRAIN IN 3-D BRAIDED COMPOSITES USING OPTIC FIBER STRAIN SENSORS
Institute of Scientific and Technical Information of China (English)
YuanShenfang; HuangRui; LiXianghua; LiuXiaohui
2004-01-01
A reliable understanding of the properties of 3-D braided composites is of primary importance for proper utilization of these materials. A new method is introduced to study the mechanical performance of braided composite materials using embedded optic fiber sensors. Experimental research is performed to devise a method of incorporating optic fibers into a 3-D braided composite structure. The efficacy of this new testing method is evaluated on two counts. First,the optical performance of optic fibers is studied before and after incorporated into 3-D braided composites, as well as after completion of the manufacturing process for 3-D braided composites,to validate the ability of the optic fiber to survive the manufacturing process. On the other hand,the influence of incorporated optic fiber on the original braided composite is also researched by tension and compression experiments. Second, two kinds of optic fiber sensors are co-embedded into 3-D braided composites to evaluate their respective ability to measure the internal strain.Experimental results show that multiple optic fiber sensors can be co-braided into 3-D braided composites to determine their internal strain which is difficult to be fulfilled by other current existing methods.
Wireless Majorana Bound States: From Magnetic Tunability to Braiding.
Fatin, Geoffrey L; Matos-Abiague, Alex; Scharf, Benedikt; Žutić, Igor
2016-08-12
We propose a versatile platform to investigate the existence of Majorana bound states (MBSs) and their non-Abelian statistics through braiding. This implementation combines a two-dimensional electron gas formed in a semiconductor quantum well grown on the surface of an s-wave superconductor with a nearby array of magnetic tunnel junctions (MTJs). The underlying magnetic textures produced by MTJs provide highly controllable topological phase transitions to confine and transport MBSs in two dimensions, overcoming the requirement for a network of wires. Obtained scaling relations confirm that various semiconductor quantum well materials are suitable for this proposal.
A complete topological invariant for braided magnetic fields
Yeates, A R
2013-01-01
A topological flux function is introduced to quantify the topology of magnetic braids: non-zero line-tied magnetic fields whose field lines all connect between two boundaries. This scalar function is an ideal invariant defined on a cross-section of the magnetic field, whose integral over the cross-section yields the relative magnetic helicity. Recognising that the topological flux function is an action in the Hamiltonian formulation of the field line equations, a simple formula for its differential is obtained. We use this to prove that the topological flux function uniquely characterises the field line mapping and hence the magnetic topology. A simple example is presented.
Braiding a Flock: Winding Statistics of Interacting Flying Spins
Caussin, Jean-Baptiste; Bartolo, Denis
2015-06-01
When animal groups move coherently in the form of a flock, their trajectories are not all parallel, the individuals exchange their position in the group. In this Letter, we introduce a measure of this mixing dynamics, which we quantify as the winding of the braid formed from the particle trajectories. Building on a paradigmatic flocking model we numerically and theoretically explain the winding statistics and show that it is predominantly set by the global twist of the trajectories as a consequence of a spontaneous symmetry breaking.
Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent
Energy Technology Data Exchange (ETDEWEB)
Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL
2014-04-30
ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.
Braided embeddings of contact 3-manifolds in the standard contact 5-sphere
Etnyre, John B.; Furukawa, Ryo
2015-01-01
In this paper we study embeddings of contact manifolds using braidings of one manifold about another. In particular we show how to embed many contact 3-manifolds into the standard contact 5-sphere. We also show how to obstruct braidings of one manifold about another using contact geometry.
On the cohomology of spaces of links and braids via configuration space integrals
Volic, Ismar
2010-01-01
We study the cohomology of spaces of string links and braids in $\\mathbb{R}^n$ for $n\\geq 3$ using configuration space integrals. For $n>3$, these integrals give a chain map from certain diagram complexes to the deRham algebra of differential forms on these spaces. For $n=3$, they produce all finite type invariants of string links and braids.
A Study on the EM Leakage Arising from Braided Shielding Cable
Institute of Scientific and Technical Information of China (English)
ZHANG Hong-xin; L(U) Ying-hua; BAO Yong-fang; L(U) Jian-gang
2005-01-01
To investigate the electromagnetic leakage caused by braided shielding cable, the finite-difference formulation of braided shielding cable for both the inner shield-conductor circuit and outer shield-ground circuit are proposed. Then, the current in shield-ground circuit induced by the transmitting signal in the cable is computed in time-domain, and the shielding effectiveness of braided shield against trapezoid signals is studied. Further more, the video EM leakage in far zone is calculated. At last, the information leakage caused by EM radiation of braided cable is intercepted and recovered using the simulation platform. It is proved that EM radiation of braided cable can give rise to information leakage. It is a key factor that should be concerned in the information secure field.
Theoretical studies on conformation comparison of braid-like and triplex DNA
Yang, Linjing; Bai, Chunli; Liu, Ciquan; Shi, Xiufan; Lee, Imshik
1999-03-01
Based on the experimental data of scanning tunneling microscopy (STM), models of three-stranded braid-like DNAs composed by three kinds of base triplets AAA, TAT and GCA were constructed. We investigated the braid-like DNAs and their comparative triplex DNAs using a molecular mechanics method. The three strands of braid-like DNAs are proven equivalent, while those of triplex DNAs are not. The conformational energies for braid-like DNAs were found to be higher than that for triplex DNAs. Each period in one strand of braid-like DNA has 18 nucleotides, half of which are right-handed, while the other half are left-handed. Additional discussions concerning sugar puckering modes and the H-bonds are also included.
Structure Design of the 3-D Braided Composite Based on a Hybrid Optimization Algorithm
Zhang, Ke
Three-dimensional braided composite has the better designable characteristic. Whereas wide application of hollow-rectangular-section three-dimensional braided composite in engineering, optimization design of the three-dimensional braided composite made by 4-step method were introduced. Firstly, the stiffness and damping characteristic analysis of the composite is presented. Then, the mathematical models for structure design of the three-dimensional braided composite were established. The objective functions are based on the specific damping capacity and stiffness of the composite. The design variables are the braiding parameters of the composites and sectional geometrical size of the composite. The optimization problem is solved by using ant colony optimization (ACO), contenting the determinate restriction. The results of numeral examples show that the better damping and stiffness characteristic could be obtained. The method proposed here is useful for the structure design of the kind of member and its engineering application.
First-order differential calculi over multi-braided quantum groups
Durdevic, M
1996-01-01
A differential calculus of the first order over multi-braided quantum groups is developed. In analogy with the standard theory, left/right-covariant and bicovariant differential structures are introduced and investigated. Furthermore, antipodally covariant calculi are studied. The concept of the *-structure on a multi-braided quantum group is formulated, and in particular the structure of left-covariant *-covariant calculi is analyzed. A special attention is given to differential calculi covariant with respect to the action of the associated braid system. In particular it is shown that the left/right braided-covariance appears as a consequence of the left/right-covariance relative to the group action. Braided counterparts of all basic results of the standard theory are found.
Factorization of differential expansion for antiparallel double-braid knots
Morozov, A.
2016-09-01
Continuing the quest for exclusive Racah matrices, which are needed for evaluation of colored arborescent-knot polynomials in Chern-Simons theory, we suggest to extract them from a new kind of a double-evolution — that of the antiparallel double-braids, which is a simple two-parametric family of two-bridge knots, generalizing the one-parametric family of twist knots. In the case of rectangular representations R = [ r s ] we found an evidence that the corresponding differential expansion miraculously factorizes and can be obtained from that for the twist knots. This reduces the problem of rectangular exclusive Racah to constructing the answers for just a few twist knots. We develop a recent conjecture on the structure of differential expansion for the simplest members of this family (the trefoil and the figure-eight knot) and provide the exhaustive answer for the first unknown case of R = [33]. The answer includes HOMFLY of arbitrary twist and double-braid knots and Racah matrices overline{S} and S — what allows to calculate [33]-colored polynomials for arbitrary arborescent (double-fat) knots. For generic rectangular representations fully described are only the contributions of the single-floor pyramids. One step still remains to be done.
Macro Scale Independently Homogenized Subcells for Modeling Braided Composites
Blinzler, Brina J.; Goldberg, Robert K.; Binienda, Wieslaw K.
2012-01-01
An analytical method has been developed to analyze the impact response of triaxially braided carbon fiber composites, including the penetration velocity and impact damage patterns. In the analytical model, the triaxial braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. Currently, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. To determine the stiffness and strength properties required for the constitutive model, a top-down approach for determining the strength properties is merged with a bottom-up approach for determining the stiffness properties. The top-down portion uses global strengths obtained from macro-scale coupon level testing to characterize the material strengths for each subcell. The bottom-up portion uses micro-scale fiber and matrix stiffness properties to characterize the material stiffness for each subcell. Simulations of quasi-static coupon level tests for several representative composites are conducted along with impact simulations.
Braided affine geometry and q-analogs of wave operators
International Nuclear Information System (INIS)
The main goal of this review is to compare different approaches to constructing the geometry associated with a Hecke type braiding (in particular, with that related to the quantum group Uq(sl(n))). We place emphasis on the affine braided geometry related to the so-called reflection equation algebra (REA). All objects of such a type of geometry are defined in the spirit of affine algebraic geometry via polynomial relations on generators. We begin by comparing the Poisson counterparts of 'quantum varieties' and describe different approaches to their quantization. Also, we exhibit two approaches to introducing q-analogs of vector bundles and defining the Chern-Connes index for them on quantum spheres. In accordance with the Serre-Swan approach, the q-vector bundles are treated as finitely generated projective modules over the corresponding quantum algebras. Besides, we describe the basic properties of the REA used in this construction and compare different ways of defining q-analogs of partial derivatives and differentials on the REA and algebras close to them. In particular, we present a way of introducing a q-differential calculus via Koszul type complexes. The elements of the q-calculus are applied to defining q-analogs of some relativistic wave operators. (topical review)
Li, Xiao-kang; Liu, Zhen-guo; Hu, Long; Wang, Yi-bo; Lei, Bing; Huang, Xiang
2016-08-01
Numerical studied on T-joints with three-dimensional four directional (3D4D) braided composite fillers was presented in this article. Compared with conventional unidirectional prepreg fillers, the 3D braided composite fillers have excellent ability to prevent crack from penetrating trigone fillers, which constantly occurred in the conventional fillers. Meanwhile, the 3D braided composite fillers had higher fiber volume fraction and eliminated the fiber folding problem in unidirectional prepreg fillers. The braiding technology and mechanical performance of 3D4D braided fillers were studied. The numerical model of carbon fiber T-joints with 3D4D braided composite fillers was built by finite element analysis software. The damage formation, extension and failing process of T-joints with 3D4D braided fillers under tensile load were investigated. Further investigation was extended to the effect of 3D4D braided fillers with different braiding angles on mechanical behavior of the T-joints. The study results revealed that the filling area was the weakest part of the T-joints where the damage first appeared and the crack then rapidly spread to the glue film around the filling area and the interface between over-laminate and soleplate. The 3D4D braided fillers were undamaged and the braiding angle change induced a little effect on the bearing capacity of T-joints.
Characterization of Biaxial and Triaxial Braids: Fiber Architecture and Mechanical Properties
Birkefeld, Karin; Röder, Mirko; von Reden, Tjark; Bulat, Martina; Drechsler, Klaus
2012-06-01
Biaxial and triaxial carbon fiber braids with off-axis braiding angles of 30°, 45° and 55° are characterized with respect to their fiber architecture. All braids are produced on a round mandrel with constant cross section. Detailed geometric information on the different braids, like roving dimensions, roving shapes and the degree of nesting is given. The findings from measurements in photomicrographs are used to construct meso-model yarn architectures at the unit cell level which are then analyzed with the WiseTex software (Lomov et al. Compos. Sci. Technol. 60:2083-2095, 2000). The results of the models' analysis with TexComp and comparison of mechanical properties with tests are consistent and essential for further steps in predictive modeling. Predictive modeling was also performed for biaxial braids based on the packing density in the material and parameters of the braiding process. The good conformance of the predictive models gives a validated starting point for development of braided structures concerning stiffness behavior. In addition, the information about the fiber architecture can be used for failure analysis on unit cell level.
Hom-Hopf group coalgebras and braided T-categories obtained from Hom-Hopf algebras
You, Miman; Zhou, Nan; Wang, Shuanhong
2015-11-01
The main aim of this paper is to provide new examples of braided T-categories in the sense of Turaev [Arabian J. Sci. Eng., Sect. C 33(2C), 483-503 (2008)]. For this purpose, we first introduce a class of new twisted Yetter-Drinfeld modules categories. Then, we construct a new braided T-category, generalizing the main constructions by Panaite and Staic [Isr. J. Math. 158, 349-366 (2007)]. Finally, we show that the new braided T-category in some conditions coincides with the representations of a certain Hom-Hopf group-coalgebra that we construct.
Alterations in braided rivers' morphology: a typology for Curvature Subcarpathians (Romania)
Ioana-Toroimac, Gabriela; Zaharia, Liliana; Ciobotaru, Nicu
2015-04-01
The morphology of braided rivers was altered by human pressures in the last century in Europe. Rivers from Curvature Subcarpathians have the highest sediment charges in Romania, therefore it seems relevant to evaluate the status of their braided sectors. Therefore, the aim of this work is to carry out an inventory of river morphology alterations suffered by braided rivers in Curvature Subcarpathians and to establish a typology based on indicators for channel adjustments and artificiality. For channel adjustments, we calculated the length of the braided sectors, the width of the active-channels and the length of banks covered by a riparian forest for 1900-2011 interval, in GIS. For artificiality, we counted dams, weirs, bridges, as well as artificial banks length for 2011 time horizon. The results indicate a diminishing braiding activity: all the rivers narrowed their braided active-channel (30-70% of the mean width); the majority suffered fluvial metamorphosis, transforming partially into single channels (0-75% of the braided sector length in 1900); artificial banks vary from 0 to 40% of the initial braided sector. We distinguished three main types of braided rivers based on morphological alterations. Type 1 includes rivers with human interventions and important braiding retraction, both upstream and downstream; a sub-type characterises by riparian forest lining the downstream metamorphosed reach; most rivers are in the south-western part of the studied region; the most demonstrative examples are Prahova and Ialomiţa rivers. Type 2 corresponds to rivers with important retraction upstream, without important values of artificiality; most demonstrative is Râmna River. Type 3 regroups rivers with a low level of channel adjustments and artificiality; actually, they had and still have the highest braiding activity in the studied region; they are located in the north-eastern part; typical examples are Putna and Şuşiţa rivers. As a discussion, the variations of active
Factorization of differential expansion for antiparallel double-braid knots
Morozov, A
2016-01-01
Continuing the quest for exclusive Racah matrices, which are needed for evaluation of colored arborescent-knot polynomials in Chern-Simons theory, we suggest to extract them from a new kind of a double-evolution -- that of the antiparallel double-braids, which is a simple two-parametric family of two-bridge knots, generalizing the one-parametric family of twist knots. In the case of rectangular representations $R=[r^s]$ we found an evidence that the corresponding differential expansion miraculously factorizes and can be obtained from that for the twist knots. This reduces the problem of rectangular exclusive Racah to constructing the answers for just a few twist knots. We develop a recent conjecture on the structure of differential expansion for the simplest members of this family -- the trefoil and the figure-eight knot,-- but manage to guess the full answer only for contributions of single-floor pyramids. One step still remains to be done.
Systematically Generated Two-Qubit Braids for Fibonacci Anyons
Zeuch, Daniel; Carnahan, Caitlin; Bonesteel, N. E.
We show how two-qubit Fibonacci anyon braids can be generated using a simple iterative procedure which, in contrast to previous methods, does not require brute force search. Our construction is closely related to that of, but with the new feature that it can be used for three-anyon qubits as well as four-anyon qubits. The iterative procedure we use, which was introduced by Reichardt, generates sequences of three-anyon weaves that asymptotically conserve the total charge of two of the three anyons, without control over the corresponding phase factors. The resulting two-qubit gates are independent of these factors and their length grows as log 1/ ɛ, where ɛ is the error, which is asymptotically better than the Solovay-Kitaev method.
Two dimensional hydrodynamic modeling of a high latitude braided river
Humphries, E.; Pavelsky, T.; Bates, P. D.
2014-12-01
Rivers are a fundamental resource to physical, ecologic and human systems, yet quantification of river flow in high-latitude environments remains limited due to the prevalence of complex morphologies, remote locations and sparse in situ monitoring equipment. Advances in hydrodynamic modeling and remote sensing technology allow us to address questions such as: How well can two-dimensional models simulate a flood wave in a highly 3-dimensional braided river environment, and how does the structure of such a flood wave differ from flow down a similar-sized single-channel river? Here, we use the raster-based hydrodynamic model LISFLOOD-FP to simulate flood waves, discharge, water surface height, and velocity measurements over a ~70 km reach of the Tanana River in Alaska. In order to use LISFLOOD-FP a digital elevation model (DEM) fused with detailed bathymetric data is required. During summer 2013, we surveyed 220,000 bathymetric points along the study reach using an echo sounder system connected to a high-precision GPS unit. The measurements are interpolated to a smooth bathymetric surface, using Topo to Raster interpolation, and combined with an existing five meter DEM (Alaska IfSAR) to create a seamless river terrain model. Flood waves are simulated using varying complexities in model solvers, then compared to gauge records and water logger data to assess major sources of model uncertainty. Velocity and flow direction maps are also assessed and quantified for detailed analysis of braided channel flow. The most accurate model output occurs with using the full two-dimensional model structure, and major inaccuracies appear to be related to DEM quality and roughness values. Future work will intercompare model outputs with extensive ground measurements and new data from AirSWOT, an airborne analog for the Surface Water and Ocean Topography (SWOT) mission, which aims to provide high-resolution measurements of terrestrial and ocean water surface elevations globally.
Software for Computing, Archiving, and Querying Semisimple Braided Monoidal Category Data
Energy Technology Data Exchange (ETDEWEB)
2016-08-04
This software package collects various open source and freely available codes and algorithms to compute and archive the categorical data for certain semisimple braided monoidal categories. In particular, it computes the data for of group theoretical categories for academic research.
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Based on unit cell model,the 3D 4-directional braided composites can be simplified as unidirectional composites with different local axial coordinate system and the compliance matrix of unidirectional composites can be defined utilizing the bridge model.The total stiffness matrix of braided composites can be obtained by the volume average stiffness of unidirectional composites with different local axial coordinate system and the engineering elastic constants of braided composites were computed further.Based on the iso-strain assumption and the bridge model,the stress distribution of fiber bundle and matrix of different unidirectional composites can be determined and the tensile strength of 3D 4-directional braided composites was predicted by means of the Hoffman's failure criterion for the fiber bundle and Mises' failure criterion for the matrix.
DAMAGE MECHANISM ANALYSIS OF 2D 1 × 1 BRAIDED COMPOSITES UNDER UNIDIRECTIONAL TENSION
Institute of Scientific and Technical Information of China (English)
张超; 许希武; 陈康
2013-01-01
Coupling with the periodical displacement boundary condition ,a representative volume element (RVE) model is established to simulate the progressive damage behavior of 2D 1 × 1 braided composites under unidirection-al tension by using the nonlinear finite element method .Tsai-Wu failure criterion with various damage modes and Mises criterion are considered for predicting damage initiation and progression of yarns and matrix .The anisotropic damage model for yarns and the isotropic damage model for matrix are used to simulate the microscopic damage propagation of 2D 1 × 1 braided composites .Murakami′s damage tensor is adopted to characterize each damage mode .In the simulation process ,the damage mechanisms are revealed and the tensile strength of 2D 1 × 1 braided composites is predicted from the calculated average stress-average strain curve . Numerical results show good agreement with experimental data ,thus the proposed simulation method is verified for damage mechanism analysis of 2D braided composites .
Evaluation of Braided Stiffener Concepts for Transport Aircraft Wing Structure Applications
Deaton, Jerry W.; Dexter, H. Benson (Editor); Markus, Alan; Rohwer, Kim
1995-01-01
Braided composite materials have potential for application in aircraft structures. Stiffeners, wing spars, floor beams, and fuselage frames are examples where braided composites could find application if cost effective processing and damage requirements are met. Braiding is an automated process for obtaining near-net shape preforms for fabrication of components for structural applications. Previous test results on braided composite materials obtained at NASA Langley indicate that damage tolerance requirements can be met for some applications. In addition, the braiding industry is taking steps to increase the material through-put to be more competitive with other preform fabrication processes. Data are presented on the compressive behavior of three braided stiffener preform fabric constructions as determined from individual stiffener crippling test and three stiffener wide panel tests. Stiffener and panel fabrication are described and compression data presented for specimens tested with and without impact damage. In addition, data are also presented on the compressive behavior of the stitched stiffener preform construction currently being used by McDonnell Douglas Aerospace in the NASA ACT wing development program.
Braiding of submarine channels controlled by aspect ratio similar to rivers
Foreman, Brady Z.; Lai, Steven Y. J.; Komatsu, Yuhei; Paola, Chris
2015-09-01
The great majority of submarine channels formed by turbidity and density currents are meandering in planform; they consist of a single, sinuous channel that transports a turbid, dense flow of sediment from submarine canyons to ocean floor environments. Braided turbidite systems consisting of multiple, interconnected channel threads are conspicuously rare. Furthermore, such systems may not represent the spontaneous planform instability of true braiding, but instead result from erosive processes or bathymetric variability. In marked contrast to submarine environments, both meandering and braided planforms are common in fluvial systems. Here we present experiments of subaqueous channel formation conducted at two laboratory facilities. We find that density currents readily produce a braided planform for flow aspect ratios of depth to width that are similar to those that produce river braiding. Moreover, we find that stability model theory for river planform morphology successfully describes submarine channels in both experiments and the field. On the basis of these observations, we propose that the rarity of braided submarine channels is explained by the generally greater flow depths in submarine systems, which necessitate commensurately greater widths to achieve the required aspect ratio, along with feedbacks among flow thickness, suspended sediment concentration and channel relief that induce greater levee deposition rates and limit channel widening.
Braided Multi-Electrode Probes (BMEPs) for Neural Interfaces
Kim, Tae Gyo
Although clinical use of invasive neural interfaces is very limited, due to safety and reliability concerns, the potential benefits of their use in brain machine interfaces (BMIs) seem promising and so they have been widely used in the research field. Microelectrodes as invasive neural interfaces are the core tool to record neural activities and their failure is a critical issue for BMI systems. Possible sources of this failure are neural tissue motions and their interactions with stiff electrode arrays or probes fixed to the skull. To overcome these tissue motion problems, we have developed novel braided multi-electrode probes (BMEPs). By interweaving ultra-fine wires into a tubular braid structure, we obtained a highly flexible multi-electrode probe. In this thesis we described BMEP designs and how to fabricate BMEPs, and explore experiments to show the advantages of BMEPs through a mechanical compliance comparison and a chronic immunohistological comparison with single 50microm nichrome wires used as a reference electrode type. Results from the mechanical compliance test showed that the bodies of BMEPs have 4 to 21 times higher compliance than the single 50microm wire and the tethers of BMEPs were 6 to 96 times higher compliance, depending on combinations of the wire size (9.6microm or 12.7microm), the wire numbers (12 or 24), and the length of tether (3, 5 or 10 mm). Results from the immunohistological comparison showed that both BMEPs and 50microm wires anchored to the skull caused stronger tissue reactions than unanchored BMEPs and 50microm wires, and 50microm wires caused stronger tissue reactions than BMEPs. In in-vivo tests with BMEPs, we succeeded in chronic recordings from the spinal cord of freely jumping frogs and in acute recordings from the spinal cord of decerebrate rats during air stepping which was evoked by mesencephalic locomotor region (MLR) stimulation. This technology may provide a stable and reliable neural interface to spinal cord
Modeling of Failure for Analysis of Triaxial Braided Carbon Fiber Composites
Goldberg, Robert K.; Littell, Justin D.; Binienda, Wieslaw K.
2010-01-01
In the development of advanced aircraft-engine fan cases and containment systems, composite materials are beginning to be used due to their low weight and high strength. The design of these structures must include the capability of withstanding impact loads from a released fan blade. Relatively complex triaxially braided fiber architectures have been found to yield the best performance for the fan cases. To properly work with and design these structures, robust analytical tools are required that can be used in the design process. A new analytical approach models triaxially braided carbon fiber composite materials within the environment of a transient dynamic finite-element code, specifically the commercially available transient dynamic finite-element code LS-DYNA. The geometry of the braided composites is approximated by a series of parallel laminated composites. The composite is modeled by using shell finite elements. The material property data are computed by examining test data from static tests on braided composites, where optical strain measurement techniques are used to examine the local strain variations within the material. These local strain data from the braided composite tests are used along with a judicious application of composite micromechanics- based methods to compute the stiffness properties of an equivalent unidirectional laminated composite required for the shell elements. The local strain data from the braided composite tests are also applied to back out strength and failure properties of the equivalent unidirectional composite. The properties utilized are geared towards the application of a continuum damage mechanics-based composite constitutive model available within LS-DYNA. The developed model can be applied to conduct impact simulations of structures composed of triaxially braided composites. The advantage of this technology is that it facilitates the analysis of the deformation and damage response of a triaxially braided polymer matrix
Lee, D J
2013-01-01
This is a technical document that outlines a calculation of an electrostatic interaction energy between two rods, with charge helices on them, forming a braid. We deal here with screened electrostatics. A general braid geometry is considered, though to obtain local expressions for the energy the curvature of the rods is considered to be small. Further approximations are made for small tilt angle. This is a generalization of the calculations given in the supplemental material of [R. Cortini et Al, Biophys. J. 101 875 (2011)] for a straight symmetric braid structure, using a different method of calculation where the braid geometry does not need to be supposed a priori.
Cater, Christopher; Xiao, Xinran; Goldberg, Robert K.; Kohlman, Lee W.
2015-01-01
A combined experimental and analytical approach was performed for characterizing and modeling triaxially braided composites with a modified subcell modeling strategy. Tensile coupon tests were conducted on a [0deg/60deg/-60deg] braided composite at angles of 0deg, 30deg, 45deg, 60deg and 90deg relative to the axial tow of the braid. It was found that measured coupon strength varied significantly with the angle of the applied load and each coupon direction exhibited unique final failures. The subcell modeling approach implemented into the finite element software LS-DYNA was used to simulate the various tensile coupon test angles. The modeling approach was successful in predicting both the coupon strength and reported failure mode for the 0deg, 30deg and 60deg loading directions. The model over-predicted the strength in the 90deg direction; however, the experimental results show a strong influence of free edge effects on damage initiation and failure. In the absence of these local free edge effects, the subcell modeling approach showed promise as a viable and computationally efficient analysis tool for triaxially braided composite structures. Future work will focus on validation of the approach for predicting the impact response of the braided composite against flat panel impact tests.
Characterization and Analysis of Triaxially Braided Polymer Composites under Static and Impact Loads
Goldberg, Robert K.; Roberts, Gary D.; Blinzler, Brina J.; Kohlman, Lee W.; Binienda, Wieslaw K.
2012-01-01
In order to design impact resistant aerospace components made of triaxially-braided polymer matrix composite materials, a need exists to have reliable impact simulation methods and a detailed understanding of the material behavior. Traditional test methods and specimen designs have yielded unrealistic material property data due to material mechanisms such as edge damage. To overcome these deficiencies, various alternative testing geometries such as notched flat coupons have been examined to alleviate difficulties observed with standard test methods. The results from the coupon level tests have been used to characterize and validate a macro level finite element-based model which can be used to simulate the mechanical and impact response of the braided composites. In the analytical model, the triaxial braid unit cell is approximated by using four parallel laminated composites, each with a different fiber layup, which roughly simulates the braid architecture. In the analysis, each of these laminated composites is modeled as a shell element. Currently, each shell element is considered to be a smeared homogeneous material. Simplified micromechanics techniques and lamination theory are used to determine the equivalent stiffness properties of each shell element, and results from the coupon level tests on the braided composite are used to back out the strength properties of each shell element. Recent improvements to the model include the incorporation of strain rate effects into the model. Simulations of ballistic impact tests have been carried out to investigate and verify the analysis approach.
Fusion and braiding in finite and affine Temperley-Lieb categories
Gainutdinov, A M
2016-01-01
Finite Temperley-Lieb (TL) algebras are diagram-algebra quotients of (the group algebra of) the famous Artin's braid group $B_N$, while the affine TL algebras arise as diagram algebras from a generalized version of the braid group. We study asymptotic `$N\\to\\infty$' representation theory of these quotients (parametrized by $q\\in\\mathbb{C}^{\\times}$) from a perspective of braided monoidal categories. Using certain idempotent subalgebras in the finite and affine algebras, we construct infinite `arc' towers of the diagram algebras and the corresponding direct system of representation categories, with terms labeled by $N\\in\\mathbb{N}$. The corresponding direct-limit category is our main object of studies. For the case of the finite TL algebras, we prove that the direct-limit category is abelian and highest-weight at any $q$ and endowed with braided monoidal structure. The most interesting result is when $q$ is a root of unity where the representation theory is non-semisimple. The resulting braided monoidal catego...
Finite Element Model for Failure Study of Two-Dimensional Triaxially Braided Composite
Li, Xuetao; Binienda, Wieslaw K.; Goldberg, Robert K.
2010-01-01
A new three-dimensional finite element model of two-dimensional triaxially braided composites is presented in this paper. This meso-scale modeling technique is used to examine and predict the deformation and damage observed in tests of straight sided specimens. A unit cell based approach is used to take into account the braiding architecture as well as the mechanical properties of the fiber tows, the matrix and the fiber tow-matrix interface. A 0 deg / plus or minus 60 deg. braiding configuration has been investigated by conducting static finite element analyses. Failure initiation and progressive degradation has been simulated in the fiber tows by use of the Hashin failure criteria and a damage evolution law. The fiber tow-matrix interface was modeled by using a cohesive zone approach to capture any fiber-matrix debonding. By comparing the analytical results to those obtained experimentally, the applicability of the developed model was assessed and the failure process was investigated.
Directory of Open Access Journals (Sweden)
Kathleen Hennecke
Full Text Available Repair success for injuries to the flexor tendon in the hand is often limited by the in vivo behaviour of the suture used for repair. Common problems associated with the choice of suture material include increased risk of infection, foreign body reactions, and inappropriate mechanical responses, particularly decreases in mechanical properties over time. Improved suture materials are therefore needed. As high-performance materials with excellent tensile strength, spider silk fibres are an extremely promising candidate for use in surgical sutures. However, the mechanical behaviour of sutures comprised of individual silk fibres braided together has not been thoroughly investigated. In the present study, we characterise the maximum tensile strength, stress, strain, elastic modulus, and fatigue response of silk sutures produced using different braiding methods to investigate the influence of braiding on the tensile properties of the sutures. The mechanical properties of conventional surgical sutures are also characterised to assess whether silk offers any advantages over conventional suture materials. The results demonstrate that braiding single spider silk fibres together produces strong sutures with excellent fatigue behaviour; the braided silk sutures exhibited tensile strengths comparable to those of conventional sutures and no loss of strength over 1000 fatigue cycles. In addition, the braiding technique had a significant influence on the tensile properties of the braided silk sutures. These results suggest that braided spider silk could be suitable for use as sutures in flexor tendon repair, providing similar tensile behaviour and improved fatigue properties compared with conventional suture materials.
Flat connections on configuration spaces and formality of braid groups of surfaces
Enriquez, B
2011-01-01
We construct an explicit bundle with flat connection on the configuration space of n points of a complex curve. This enables one to recover the `formality' isomorphism between the Lie algebra of the prounipotent completion of the pure braid group of n points on a surface and an explicitly presented Lie algebra t_{g,n} (Bezrukavnikov), and to extend it to a morphism from the full braid group of the surface to the semidirect product exp(hat t_{g,n}) rtimes S_n.
Observational Constraints on Kinetic Gravity Braiding from the Integrated Sachs-Wolfe Effect
Kimura, Rampei; Kobayashi, Tsutomu; Yamamoto, Kazuhiro
2011-01-01
The cross-correlation between the integrated Sachs-Wolfe (ISW) effect and the large scale structure (LSS) is a powerful tool to constrain dark energy and alternative theories of gravity. In this paper, we obtain observational constraints on kinetic gravity braiding from the ISW-LSS cross-correlation. We find that the late-time ISW effect in the kinetic gravity braiding model anti-correlates with large scale structures in a wide range of parameters, which clearly demonstrates how one can disti...
Review of the origin of the Braid Scarp near the Pebble prospect, southwestern Alaska
Haeussler, Peter J.; Waythomas, Christopher F.
2011-01-01
A linear geomorphic scarp, referred to as the 'Braid Scarp,' lies about 5 kilometers north of Iliamna Lake, Alaska, and has been identified as a possible seismically active fault. We examined the geomorphology of the area and an 8.5-meter-long excavation across the scarp. We conclude that the scarp was formed by incision of a glacial outwash braid plain into a slightly older outwash plain as ice stagnated in the region during deglaciation 11-15 thousand years ago. We found no evidence for active faulting along the scarp.
Categorical action of the extended braid group of affine type A
Gadbled, Agnes; Thiel, Anne-Laure; Wagner, Emmanuel
2015-01-01
Using a quiver algebra of a cyclic quiver, we construct a faithful categorical action of the extended braid group of affine type A on its bounded homotopy category of finitely generated projective modules. The algebra is trigraded and we identify the trigraded dimensions of the space of morphisms of this category with intersection numbers coming from the topological origin of the group.
Braiding and fusion properties of the Neveu-Schwarz super-conformal blocks
Chorazkiewicz, Damian
2009-01-01
We construct, generalizing appropriately the method applied by J. Teschner in the case of the Virasoro conformal blocks, the braiding and fusion matrices of the Neveu-Schwarz super-conformal blocks. Their properties allow for an explicit verification of the bootstrap equation in the NS sector of the N=1 supersymmetric Liouville field theory.
Braiding properties of the N=1 super-conformal blocks (Ramond sector)
Chorazkiewicz, Damian; Jaskolski, Zbigniew
2011-01-01
Using a super scalar field representation of the chiral vertex operators we develop a general method of calculating braiding matrices for all types of N=1 super-conformal 4-point blocks involving Ramond external weights. We give explicit analytic formulae in a number of cases.
Investigation of a Macromechanical Approach to Analyzing Triaxially-Braided Polymer Composites
Goldberg, Robert K.; Blinzler, Brina J.; Binienda, Wieslaw K.
2010-01-01
A macro level finite element-based model has been developed to simulate the mechanical and impact response of triaxially-braided polymer matrix composites. In the analytical model, the triaxial braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The material stiffness and strength values required for the constitutive model are determined based on coupon level tests on the braided composite. Simulations of quasi-static coupon tests of a representative braided composite are conducted. Varying the strength values that are input to the material model is found to have a significant influence on the effective material response predicted by the finite element analysis, sometimes in ways that at first glance appear non-intuitive. A parametric study involving the input strength parameters provides guidance on how the analysis model can be improved.
Grain sorting in the morphological active layer of a braided river physical model
Leduc, P.; Ashmore, P.; Gardner, J. T.
2015-07-01
A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer aggregated over the width of the river. This vertical sorting is important for analyzing braided river sedimentology, for numerical modeling of braided river morpho-dynamics and for measuring and predicting bed load transport rate. We define the morphological active layer as the bed material between the maximum and minimum bed elevations at a point over extended time periods sufficient for braiding processes to re-work the river bed. The vertical extent of the active layer was measured using 40 hourly high-resolution DEMs of the model river bed. An image texture algorithm was used to map bed material grain size of each DEM. Analysis of the 40 DEMs and texture maps provides data on the geometry of the morphological active layer and variation in grain size in three-dimensions. Normalizing active layer thickness and dividing into 10 sub-layers we show that all grain sizes occur with almost equal frequency in all sub-layers. Occurrence of patches and strings of coarser (or finer) material relates to preservation of particular morpho-textural features within the active layer. For numerical modeling and bed load prediction a morphological active layer that is fully mixed with respect to grain size is a reliable approximation.
Trigger Mechanism of Solar Subflares in a Braided Coronal Magnetic Structure
Tiwari, Sanjiv K; Winebarger, Amy R; Moore, Ronald L
2014-01-01
Fine-scale braiding of coronal magnetic loops by continuous footpoint motions may power coronal heating via nanoflares, which are spontaneous fine-scale bursts of internal reconnection. An initial nanoflare may trigger an avalanche of reconnection of the braids, making a microflare or larger subflare. In contrast to this internal triggering of subflares, we observe external triggering of subflares in a braided coronal magnetic field observed by the {\\it High-resolution Coronal Imager (Hi-C)}. We track the development of these subflares using 12 s cadence images acquired by {\\it SDO}/AIA in 1600, 193, 94 \\AA, and registered magnetograms of {\\it SDO}/HMI, over four hours centered on the {\\it Hi-C} observing time. These data show numerous recurring small-scale brightenings in transition-region emission happening on polarity inversion lines where flux cancellation is occurring. We present in detail an example of an apparent burst of reconnection of two loops in the transition region under the braided coronal fiel...
(Re)braiding to Tell: Using "Trenzas" as a Metaphorical-Analytical Tool in Qualitative Research
Quiñones, Sandra
2016-01-01
Metaphors can be used in qualitative research to illuminate the meanings of participant experiences and examine phenomena from insightful and creative perspectives. The purpose of this paper is to illustrate how I utilized "trenzas" (braids) as a metaphorical and analytical tool for understanding the experiences and perspectives of…
Littell, Justin D.; Binienda, Wieslaw K.; Arnold, William A.; Roberts, Gary D.; Goldberg, Robert K.
2010-01-01
The reliability of impact simulations for aircraft components made with triaxial-braided carbon-fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Methods to characterize the material properties used in the analytical models from a systematically obtained set of test data are also lacking. A macroscopic finite element based analytical model to analyze the impact response of these materials has been developed. The stiffness and strength properties utilized in the material model are obtained from a set of quasi-static in-plane tension, compression and shear coupon level tests. Full-field optical strain measurement techniques are applied in the testing, and the results are used to help in characterizing the model. The unit cell of the braided composite is modeled as a series of shell elements, where each element is modeled as a laminated composite. The braided architecture can thus be approximated within the analytical model. The transient dynamic finite element code LS-DYNA is utilized to conduct the finite element simulations, and an internal LS-DYNA constitutive model is utilized in the analysis. Methods to obtain the stiffness and strength properties required by the constitutive model from the available test data are developed. Simulations of quasi-static coupon tests and impact tests of a represented braided composite are conducted. Overall, the developed method shows promise, but improvements that are needed in test and analysis methods for better predictive capability are examined.
Littell, Justin D.; Binienda, Wieslaw K.; Goldberg, Robert K.; Roberts, Gary D.
2008-01-01
Quasi-static tests have been performed on triaxially braided carbon fiber composite materials with large unit cell sizes. The effects of different fibers and matrix materials on the failure mode were investigated. Simulations of the tests have been performed using the transient dynamic finite element code, LS-DYNA. However, the wide range of failure modes observed for the triaxial braided carbon fiber composites during tests could not be simulated using composite material models currently available within LS-DYNA. A macroscopic approach has been developed that provides better simulation of the material response in these materials. This approach uses full-field optical measurement techniques to measure local failures during quasi-static testing. Information from these experiments is then used along with the current material models available in LS-DYNA to simulate the influence of the braided architecture on the failure process. This method uses two-dimensional shell elements with integration points through the thickness of the elements to represent the different layers of braid along with a new analytical method for the import of material stiffness and failure data directly. The present method is being used to examine the effect of material properties on the failure process. The experimental approaches used to obtain the required data will be described, and preliminary results of the numerical analysis will be presented.
Design and Testing of Braided Composite Fan Case Materials and Components
Roberts, Gary D.; Pereira, J. Michael; Braley, Michael S.; Arnold, William a.; Dorer, James D.; Watson, William R/.
2009-01-01
Triaxial braid composite materials are beginning to be used in fan cases for commercial gas turbine engines. The primary benefit for the use of composite materials is reduced weight and the associated reduction in fuel consumption. However, there are also cost benefits in some applications. This paper presents a description of the braided composite materials and discusses aspects of the braiding process that can be utilized for efficient fabrication of composite cases. The paper also presents an approach that was developed for evaluating the braided composite materials and composite fan cases in a ballistic impact laboratory. Impact of composite panels with a soft projectile is used for materials evaluation. Impact of composite fan cases with fan blades or blade-like projectiles is used to evaluate containment capability. A post-impact structural load test is used to evaluate the capability of the impacted fan case to survive dynamic loads during engine spool down. Validation of these new test methods is demonstrated by comparison with results of engine blade-out tests.
Analysis of the spatiotemporal planform dynamics of braided rivers: a novel laboratory investigation
Redolfi, Marco; Bertoldi, Walter; Tubino, Marco
2016-04-01
Braided rivers are highly dynamic, labile environments which experience significant morphological changes even during moderate flow events. Recent remote sensing techniques enable to monitor the river morphology with great detail. However, capturing the rapid morphological changes of a large river with sufficient temporal and spatial resolution is still very challenging. As a consequence, quantitative analysis of the braided channel dynamics is often limited to local processes (e.g. a single bifurcation or confluence) and short time periods (e.g. a single flood). This work aims at providing quantitative, statistical description of the channel network dynamics in a braided network at larger spatial and temporal scales, namely the reach scale and the multiple flood scale. This can be achieved using a new technique based on time lapse imagery that we recently developed at the University of Trento. This technique provides high frequency, two dimensional maps of the bed load transport in a large laboratory model, thus allowing to capture the spatiotemporal variability of the transport processes with unprecedented detail. We performed a set of laboratory experiments in a 23 m long, 3 m wide flume, sand bed load flume, where self-formed braided networks can be reproduced. We run several experiments with different discharges and channel widths, lasting for a long time (from 20 to 65 hours) to enable a robust statistical description of the equilibrium morphodynamics. High-resolution pictures were taken at 1 min interval from two SLR cameras, then rectified and merged in order to cover a 7 m long reach. We processed a large number of images to obtain maps of bed load transport, and we developed an algorithm to automatically identifies active (i.e. transporting) channels, bifurcations and confluences. The statistical analysis we performed includes two dimensional correlations, spatial and temporal scales, channel migration rate, avulsion frequency, bank erosion rate. This
van den Berg, J. H.; Schuurman, F.; Kleinhans, M. G.; Lentink, H.
2010-12-01
Our objective is to understand general causes of different river channel patterns in unconfined alluvial plains. We discuss the principles and compare the performance of an empirical stream power-based classification and a physics-based bar pattern predictor. We present a careful selection of data from literature that contains rivers with discharge and median bed particle size ranging several orders of magnitude with various channel patterns and bar types, but no obvious eroding or aggrading tendency. Empirically a continuum of patterns is found for increasing specific stream power from single-thread, laterally immobile channels, meandering styles with scroll bars and with chute bars and moderately and highly braided channel patterns. Stream power is calculated with pattern-independent variables: mean annual flood, valley gradient and channel width predicted with a hydraulic geometry relation. `Thresholds', above which these patterns emerge, increase with bed sediment size. Linear bar theory predicts nature and presence of bars and bar mode, here converted to active braiding index. The most important variables are actual width-to-depth ratio and nonlinearity of bed sediment transport. Numerical modelling with the same equations as underlying the bar theory allow for nonlinear effects. We modelled hypothetical rivers over a large range of stream power and particle sizes with various choices for hydraulic roughness, sediment transport and transverse slope relations. Results agree well with the empirical diagram as well as empirical relations for bar and channel dimensions. Increasing potential specific stream power implies more energy to erode banks and indeed correlates to channels with high width-to-depth ratio. Bar theory and numerical modelling predict that such rivers develop more bars across the width (higher braiding index). At the transition from meandering to braiding weakly braided rivers and meandering rivers with chutes are found in nature and in the
Ya, Jixuan; Liu, Zhenguo; Wang, Yuanhang
2016-09-01
The meso-structure is important in predicting mechanical properties of the three-dimensional (3D) braided composite. In this paper, the internal structure and porosity of three-dimensional full five-directional (3DF5D) braided composite is characterized at mesoscopic scale (the scale of the yarns) using micro-computed tomography (micro-CT) non-destructively. Glass fiber yarns as tracer are added into the sample made of carbon fiber to enhance the contrast in the sectional images. The model of tracer yarns is established with 3D reconstruction method to analyze the cross-section and path of yarns. The porosities are reconstructed and characterized in the end. The results demonstrate that the cross sections of braiding yarns and axial yarns change with the regions and the heights in one pitch of 3DF5D braided composites. The path of braiding yarns are various in the different regions while the axial yarns are always straight. Helical indentations appear on the surfaces of the axial yarns because of the squeeze from braiding yarns. Moreover, the porosities in different shapes and sizes are almost located in the matrix and between the yarns.
Quantum field theory of particles with braid group statistics in 2+1 dimensions
Mund, J K H
1997-01-01
The present thesis is concerned with the local quantum physics of relativistic particles and fields in three space-time dimensions, whose statistics is to be described by a representation of the braid group -- so-called plektons or, if the representation is Abelian, anyons. In particular the issue of the existence of free anyonic fields is addressed. In our context, these are operators affiliated with the 'local' field algebras and creating only single particle vectors from the vacuum. (Localizability here refers to regions extending to infinity in some spacelike direction.) Under a mild regularity condition for these fields, we can derive commutation relations which are not compatible with braid group statistics. Further, model-independent results concerning the PCT operator and the connection of spin and statistics are obtained. Assuming the observable algebra to satisfy the Bisognano-Wichmann theorem, a PCT theorem for plektons is derived. For anyons it is shown that the Bisognano-Wichmann property of the ...
Zhang, Chao; Binienda, Wieslaw K.; Morscher, Gregory; Martin, Richard E.
2012-01-01
The microcrack distribution and mass change in PR520/T700s and 3502/T700s carbon/epoxy braided composites exposed to thermal cycling was evaluated experimentally. Acoustic emission was utilized to record the crack initiation and propagation under cyclic thermal loading between -55 C and 120 C. Transverse microcrack morphology was investigated using X-ray Computed Tomography. Different performance of two kinds of composites was discovered and analyzed. Based on the observations of microcrack formation, a meso-mechanical finite element model was developed to obtain the resultant mechanical properties. The simulation results exhibited a decrease in strength and stiffness with increasing crack density. Strength and stiffness reduction versus crack densities in different orientations were compared. The changes of global mechanical behavior in both axial and transverse loading conditions were studied. Keywords: Thermal cycles; Microcrack; Finite Element Model; Braided Composite
Yarn Architecture Analysis of Two-step 3D Braided Composites
Institute of Scientific and Technical Information of China (English)
SUN Ying; KANG Yi-lan; LI Jia-lu
2005-01-01
A comprehensive study of yarn architecture of two-step rectangle 3D braided composites is presented. Firstly, the braided surface, the shapes of yams and the intertwining between braider yarns and axial yarns are analyzed from experimentation. With the microstructure being defined, three levels of unit cell structure are identified, i.e. large unit cell, second unit cell and minimal unit cell. Secondly, based on the minimal unit cell in the interior and on the boundary of the entire cross-section, the deformations of axial yarns squashed by braider yams contribute to the increase of the fiber packing factors of axial yarns. Finally, the predicted fiber volume fraction of the composites decreases with the increase of linear density of the braider yarn and the pitch length. Favorable correlations between the predicted and the experimental results are found for six groups of the composites.
Kinetic Gravity Braiding and axion inflation in the light of BICEP2 and PLANCK
Maity, Debaprasad
2014-01-01
Based on our previous work, we constructed a phenomenological model of inflation with the higher derivative axion field in the light of recent cosmological expertiments BICEP2 and PLANCK. In order to achieve observed values for the important cosmological parameters $(n_s,r)$ we employ higher derivative kinetic term called kinetic gravity braiding (KGB) for the axion in compatible with the constant shift symmetry. Phenomenologically we choose a particular form of the braiding function $M(\\phi)$ which correctly reproduces the observed value of $(n_s, r)$ based on the recent cosmological observations. Furthermore we also find axion decay constant $f$ and the scale of inflation $\\Lambda$ to be naturally sub-Planckian consistent with the reheating after the end of inflation. Within the sufficient number of e-folding ${\\cal N}$, we also find sub-Planckian field excursion for the axion field $\\Delta \\phi \\simeq f$.
The algebraic crossing number and the braid index of knots and links
Kawamuro, Keiko
2009-01-01
It has been conjectured that the algebraic crossing number of a link is uniquely determined in minimal braid representation. This conjecture is true for many classes of knots and links. The Morton-Franks-Williams inequality gives a lower bound for braid index. And sharpness of the inequality on a knot type implies the truth of the conjecture for the knot type. We prove that there are infinitely many examples of knots and links for which the inequality is not sharp but the conjecture is still true. We also show that if the conjecture is true for K and L, then it is also true for the (p,q)-cable of K and for the connect sum of K and L.
From representations of the braid group to solutions of the Yang-Baxter equation
International Nuclear Information System (INIS)
A systematic method is developed for constructing solutions of the Yang-Baxter equation from given braid group representations, arising from such finite dimensional irreps of quantum groups that any irrep can be affinized and the tensor product of the irrep with itself is multiplicity-free. The main tool used in the construction is a tensor product graph, whose circuits give rise to consistency conditions. A maximal tree of this graph leads to an explicit formula for the quantum R-matrix when the consistency conditions are satisfied. As examples, new solutions of the Xang-Baxter equations are found, corresponding to braid group generators associated with the symmetric and antisymmetric tensor irreps of Uq[gl(m)], a spinor irrep of Uq[so(2n)], and the minimal irreps of Uq[E6] and Uq[E7]. (orig.)
Zou, Qiuhua; Xue, Wen; Lin, Jing; Fu, Yijun; Guan, Guoping; Wang, Fujun; Wang, Lu
Stents have been widely used in percutaneous surgery to treat stenosis diseases. The braided NiTi stent, as a promising prototype, still has limitations of low radial force and loose structure. In the present study, a newly integrated composite stent was designed and braided with NiTi wires and polyester multifilament yarns by textile technology. The mechanical properties of four composite stents and the control bare NiTi stent were evaluated by in vitro compression, bending and anti-torsion tests. The results showed that integrated polyester/NiTi composite stents were superior in radial support. The stents could keep patency even when highly curved and had lower stent straightening force. Composite stents with certain structure stayed stable under twisting. The configuration of NiTi wires in composite stents could significantly impact stent deformation under twisting.
On some 3-point functions in the $W_4$ CFT and related braiding matrix
Furlan, P
2015-01-01
We construct a class of 3-point constants in the $sl(4)$ Toda conformal theory $W_4$, extending the examples in Fateev and Litvinov. Their knowledge allows to determine the braiding/fusing matrix transforming 4-point conformal blocks of one fundamental, labelled by the 6-dimensional $sl(4)$ representation, and three partially degenerate vertex operators. It is a $3 \\times 3$ submatrix of the generic $6 \\times 6$ fusing matrix consistent with the fusion rules for the particular class of representations. We check a braiding relation which has wider applications to conformal models with $sl(4)$ symmetry. The 3-point constants in dual regions of central charge are compared in preparation for a BPS like relation in the $\\hat{sl}(4)$ WZW model.
Braid group representations from a deformation of the harmonic oscillator algebra
Tarlini, Marco
2016-01-01
We describe a new technique to obtain representations of the braid group B_n from the R-matrix of a quantum deformed algebra of the one dimensional harmonic oscillator. We consider the action of the R-matrix not on the tensor product of representations of the algebra, that in the harmonic oscillator case are infinite dimensional, but on the subspace of the tensor product corresponding to the lowest weight vectors.
The Effects of Spatial Resolution and Dimensionality on Modeling Braided River Hydraulics
Altenau, E. H.; Pavelsky, T.; Bates, P. D.
2015-12-01
Braided rivers are challenging features to quantify due to their dynamic morphology and dominance in remote locations. Advances in hydrodynamic modeling and remote sensing over the past few decades offer opportunities to explore braided river processes at finer resolutions with increased efficiency. These methods allow us to address questions such as: What model structure is necessary to accurately reproduce inundation extent and water surface elevations in a braided river? What effects do the smaller channels within a braided river have on simulating wave propagation and slope? How much accuracy is lost as model resolution and dimension are decreased? Here, we use the raster-based hydrodynamic model LISFLOOD-FP to simulate water surface elevations, inundation extent, and slope at various resolutions and dimensions over a ~90 km reach of the Tanana River, Alaska. Model input and validation data were collected during two field campaigns in the summers of 2013 and 2015. Field data included water surface elevation, discharge, velocity, slope, and bathymetric measurements. Six models are run to simulate flood waves across the study reach over a two-month timespan. The model structures vary in complexity from a full 2D model at 10 m resolution to a coupled 1D/2D model at 100 m resolution where the channel is represented in 1D by an effective centerline within a 2D floodplain grid. Results from the different models are compared to assess the effects on inundation extent, wave celerity, water elevations and slope. Digital elevation model (DEM) quality and resolution have major effects on inundation extent and water surface elevations, while model dimensionality has a larger effect on wave celerity and slope. Future work will compare model outputs with AirSWOT data, an airborne analog for the Surface Water and Ocean Topography (SWOT) mission, which aims to provide high-resolution measurements of terrestrial and ocean water surface elevations globally.
GoldenBraid: an iterative cloning system for standardized assembly of reusable genetic modules.
Directory of Open Access Journals (Sweden)
Alejandro Sarrion-Perdigones
Full Text Available Synthetic Biology requires efficient and versatile DNA assembly systems to facilitate the building of new genetic modules/pathways from basic DNA parts in a standardized way. Here we present GoldenBraid (GB, a standardized assembly system based on type IIS restriction enzymes that allows the indefinite growth of reusable gene modules made of standardized DNA pieces. The GB system consists of a set of four destination plasmids (pDGBs designed to incorporate multipartite assemblies made of standard DNA parts and to combine them binarily to build increasingly complex multigene constructs. The relative position of type IIS restriction sites inside pDGB vectors introduces a double loop ("braid" topology in the cloning strategy that allows the indefinite growth of composite parts through the succession of iterative assembling steps, while the overall simplicity of the system is maintained. We propose the use of GoldenBraid as an assembly standard for Plant Synthetic Biology. For this purpose we have GB-adapted a set of binary plasmids for A. tumefaciens-mediated plant transformation. Fast GB-engineering of several multigene T-DNAs, including two alternative modules made of five reusable devices each, and comprising a total of 19 basic parts are also described.
Full-field Strain Methods for Investigating Failure Mechanisms in Triaxial Braided Composites
Littell, Justin D.; Binienda, Wieslaw K.; Goldberg, Robert K.; Roberts, Gary D.
2008-01-01
Composite materials made with triaxial braid architecture and large tow size carbon fibers are beginning to be used in many applications, including composite aircraft and engine structures. Recent advancements in braiding technology have led to commercially viable manufacturing approaches for making large structures with complex shape. Although the large unit cell size of these materials is an advantage for manufacturing efficiency, the fiber architecture presents some challenges for materials characterization, design, and analysis. In some cases, the static load capability of structures made using these materials has been higher than expected based on material strength properties measured using standard coupon tests. A potential problem with using standard tests methods for these materials is that the unit cell size can be an unacceptably large fraction of the specimen dimensions. More detailed investigation of deformation and failure processes in large unit cell size triaxial braid composites is needed to evaluate the applicability of standard test methods for these materials and to develop alternative testing approaches. In recent years, commercial equipment has become available that enables digital image correlation to be used on a more routine basis for investigation of full field 3D deformation in materials and structures. In this paper, some new techniques that have been developed to investigate local deformation and failure using digital image correlation techniques are presented. The methods were used to measure both local and global strains during standard straight-sided coupon tensile tests on composite materials made with 12 and 24 k yarns and a 0/+60/-60 triaxial braid architecture. Local deformation and failure within fiber bundles was observed, and this local failure had a significant effect on global stiffness and strength. The matrix material had a large effect on local damage initiation for the two matrix materials used in this investigation
Quantifying braided river morphodynamics through a sequence of high-flow events
Williams, R. D.; Brasington, J.; Vericat, D.; Hicks, D. M.
2012-04-01
Quantifying braided river morphology and morphological change is a key task for understanding braided river behaviour. In the last decade, developments in geomatics technologies and associated data processing toolboxes have transformed the potential for producing precise, reach-scale topographic datasets. Moreover, since fast data acquisition rates enable surveys to be undertaken at frequencies that are commensurate with individual flood events, it is now possible to map morphological change for sequences of high-flow events over considerable spatial extents. The application of high-resolution remote sensing technologies to monitor braided river dynamics thus has the potential to provide considerable insight into the relationships between forcing discharges, sediment transport and morphological evolution. In this paper we present a set of Digital Elevation Models (DEMs) that have been produced by monitoring the evolution of a 2.5 x 0.7 km braided study area of the Rees River, New Zealand, through a sequence of ten high-flow events over an eight-month period. We then use the morphological approach to produce a sediment budget for the study area. The morphological evolution of the Rees River braided study area was monitored after each storm event using a combination of two remote sensing methodologies. First, dry areas of the braidplain were surveyed using a Terrestrial Laser Scanner (TLS) mounted on an Argo Amphibious All Terrain Vehicle. Second, since the TLS was not water penetrating, bathymetry was mapped using an empirically calibrated optical method, based on non-metric vertical aerial photos acquired from a helicopter and an acoustic depth survey along primary anabranches. The resulting data were fused together to produce high quality DEMs, with sub-cm and sub-decimetre vertical standard deviations of error for the TLS and optical-empirical bathymetric components respectively. The resulting set of DEMs enabled the quantification of morphological change through
Goldberg, Robert K.; Blinzler, Brina J.; Binienda, Wieslaw K.
2010-01-01
A macro level finite element-based model has been developed to simulate the mechanical and impact response of triaxially-braided polymer matrix composites. In the analytical model, the triaxial braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. For the current analytical approach, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The constitutive model requires stiffness and strength properties of an equivalent unidirectional composite. Simplified micromechanics methods are used to determine the equivalent stiffness properties, and results from coupon level tests on the braided composite are utilized to back out the required strength properties. Simulations of quasi-static coupon tests of several representative braided composites are conducted to demonstrate the correlation of the model. Impact simulations of a represented braided composites are conducted to demonstrate the capability of the model to predict the penetration velocity and damage patterns obtained experimentally.
Lei, Bing; Liu, Zhenguo; Ya, Jixuan; Wang, Yibo; Li, Xiaokang
2016-08-01
Cut-edge is a kind of damage for the three-dimensional four-directional (3D4d) braided composites which is inevitable because of machining to meet requisite shape and working in the abominable environment. The longitudinal tensile experiment of the 3D4d braided composites with different braiding angles between cut-edge and the ones without cut-edge was conducted. Then representative volume cell (RVC) with interface zones was established to analyze the tensile properties through the fracture and damage mechanics. The periodic boundary conditions under the cut-edge and uncut-edge conditions were imposed to simulate the failure mechanism. Stress-strain distribution and the damage evolution nephogram in cut-edge condition were conducted. Numerical results were coincident with the experimental results. Finally the variation of cut-edge effect with the specimen thickness was simulated by superimposing inner cells. The consequence showed that thickness increase can effectively reduce cut-edge influence on longitudinal strength for 3D4d braided composites. Cut-edge simulation of braided composites has guiding significance on the actual engineering application.
Structure and properties of braided sleeve preforms for chemical vapor infiltration
Energy Technology Data Exchange (ETDEWEB)
Starr, T.L.; Fiadzo, O.G.; Hablutzel, N. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Technology
1998-04-01
In all composites the properties and structure of the reinforcement strongly influence the performance of the material. For some composites, however, the reinforcement also affects the fabrication process itself exerting an additional, second order influence on performance. This is the case for the chemical vapor infiltration (CVI) process for fabrication of ceramic matrix composites. In this process the matrix forms progressively as a solid deposit, first onto the fiber surfaces, then onto the previous layer of deposit, ultimately growing to fill the inter-fiber porosity. The transport of reactants to the surfaces and the evolved morphology of the matrix depend on the initial reinforcement structure. This structure can vary greatly and is controlled by such factors as fiber size and cross-section, the number of filaments and amount of twist per tow or yarn, and the weave or braid architecture. Often the choice of reinforcement is based on mechanical performance analysis or on the cost and availability of the material or on the temperature stability of the fiber. Given this choice, the composite densification process--CVI--must be optimized to attain a successful material. Ceramic fiber in the form of cylindrical braided sleeve is an attractive choice for fabrication of tube-form ceramic matrix composites. Multiple, concentric layers of sleeve can be placed over a tubular mandrel, compressed and fixed with a binder to form a freestanding tube preform. This fiber architecture is different than that created by layup of plain weave cloth--the material used in most previous CVI development. This report presents the results of the investigation of CVI densification of braided sleeve preforms and the evolution of their structure and transport properties during processing.
Template synthesis of braided gold nanowires with gemini surfactant-HAuCl{sub 4} aggregates
Energy Technology Data Exchange (ETDEWEB)
Wang Wentao; Han Yuchun; Gao Mingyuan, E-mail: gaomy@iccas.ac.cn; Wang Yilin, E-mail: yilinwang@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Key Laboratory of Colloid and Interface Science (China)
2013-01-15
One-dimensional braided gold nanowires with 40-50 nm in width and several micrometers in length which were fabricated by using cationic gemini surfactant hexamethylene-1,6-bis (dodecyl dimethylammonium bromide) (C{sub 12}C{sub 6}C{sub 12}Br{sub 2}). Through simply regulating the mole ratio of C{sub 12}C{sub 6}C{sub 12}Br{sub 2} to HAuCl{sub 4}, the morphology of the gold products changed into nanoparticles and nanowires. The CryoTEM images indicated that the C{sub 12}C{sub 6}C{sub 12}Br{sub 2}/HAuCl{sub 4} mixture formed spherical or fibrillar aggregates depending on the mole ratio of C{sub 12}C{sub 6}C{sub 12}Br{sub 2} to HAuCl{sub 4}, which performed as the versatile templates for morphology-controlled synthesis of the multiple gold nanomaterials. The HRTEM and SAED results suggested the nanowires and braided nanowires were polycrystalline. The gold nanostructure displayed a time-dependent growth process, i.e., first the nanoparticles arranged in one dimension, and then assembled into nanowires. Therefore, a template-directed aggregation and fusion process of nanoparticles is proposed for the formation of the one-dimensional gold nanomaterials. The braided nanowires exhibited a higher catalytic activity in the reduction of p-nitroaniline than that of the nanowires. This gemini surfactant-based template provides a versatile strategy for the morphology-controlled synthesis of gold nanomaterials, and may be applied for the synthesis of other noble-metal nanomaterials.
Holistic and Consistent Design Process for Hollow Structures Based on Braided Textiles and RTM
Gnädinger, Florian; Karcher, Michael; Henning, Frank; Middendorf, Peter
2014-06-01
The present paper elaborates a holistic and consistent design process for 2D braided composites in conjunction with Resin Transfer Moulding (RTM). These technologies allow a cost-effective production of composites due to their high degree of automation. Literature can be found that deals with specific tasks of the respective technologies but there is no work available that embraces the complete process chain. Therefore, an overall design process is developed within the present paper. It is based on a correlated conduction of sub-design processes for the braided preform, RTM-injection, mandrel plus mould and manufacturing. For each sub-process both, individual tasks and reasonable methods to accomplish them are presented. The information flow within the design process is specified and interdependences are illustrated. Composite designers will be equipped with an efficient set of tools because the respective methods regard the complexity of the part. The design process is applied for a demonstrator in a case study. The individual sub-design processes are accomplished exemplarily to judge about the feasibility of the presented work. For validation reasons, predicted braiding angles and fibre volume fractions are compared with measured ones and a filling and curing simulation based on PAM-RTM is checked against mould filling studies. Tool concepts for a RTM mould and mandrels that realise undercuts are tested. The individual process parameters for manufacturing are derived from previous design steps. Furthermore, the compatibility of the chosen fibre and matrix system is investigated based on pictures of a scanning electron microscope (SEM). The annual production volume of the demonstrator part is estimated based on these findings.
Quantum entanglement: the unitary 8-vertex braid matrix with imaginary rapidity
International Nuclear Information System (INIS)
We study quantum entanglements induced on product states by the action of 8-vertex braid matrices, rendered unitary with purely imaginary spectral parameters (rapidity). The unitarity is displayed via the 'canonical factorization' of the coefficients of the projectors spanning the basis. This adds one more new facet to the famous and fascinating features of the 8-vertex model. The double periodicity and the analytic properties of the elliptic functions involved lead to a rich structure of the 3-tangle quantifying the entanglement. We thus explore the complex relationship between topological and quantum entanglement. (fast track communication)
EVOLUTION OF SPINNING AND BRAIDING HELICITY FLUXES IN SOLAR ACTIVE REGION NOAA 10930
International Nuclear Information System (INIS)
The line-of-sight magnetograms from Solar Optical Telescope Narrowband Filter Imager observations of NOAA Active Region 10930 have been used to study the evolution of spinning and braiding helicities over a period of five days starting from 2006 December 9. The north (N) polarity sunspot was the follower and the south (S) polarity sunspot was the leader. The N-polarity sunspot in the active region was rotating in the counterclockwise direction. The rate of rotation was small during the first two days of observations and it increased up to 8° hr–1 on the third day of the observations. On the fourth and fifth days it remained at 4° hr–1 with small undulations in its magnitude. The sunspot rotated about 260° in the last three days. The S-polarity sunspot did not complete more than 20° in five days. However, it changed its direction of rotation five times over a period of five days and injected both the positive and negative type of spin helicity fluxes into the corona. Through the five days, both the positive and negative sunspot regions injected equal amounts of spin helicity. The total injected helicity is predominantly negative in sign. However, the sign of the spin and braiding helicity fluxes computed over all the regions were reversed from negative to positive five times during the five-day period of observations. The reversal in spinning helicity flux was found before the onset of the X3.4-class flare, too. Though, the rotating sunspot has been observed in this active region, the braiding helicity has contributed more to the total accumulated helicity than the spinning helicity. The accumulated helicity is in excess of –7 × 1043 Mx2 over a period of five days. Before the X3.4-class flare that occurred on 2006 December 13, the rotation speed and spin helicity flux increased in the S-polarity sunspot. Before the flare, the total injected helicity was larger than –6 × 1043 Mx2. The observed reversal in the sign of spinning and braiding helicity
Laboratory experimental investigations of braid theory using the rotor-oscillator flow
Filippi, Margaux; Atis, Séverine; Allshouse, Michael; Jacobs, Gustaaf; Budišić, Marko; Thiffeault, Jean-Luc; Peacock, Thomas
2015-11-01
Interpreting ocean surface dynamics is crucial to many areas of oceanography, ranging from marine ecology to pollution management. Motivated by this, we investigated the braid theory method to detect transport barriers bounding coherent structures in two-dimensional flows. Whereas most existing techniques rely on an extensive spatiotemporal knowledge of the flow field, we sought to identify these structures from sparse data sets involving trajectories of a few tracer particles in a two-dimensional flow. We present the results from our laboratory experiments, which were based on investigations using the rotor-oscillator flow, as a stepping stone towards oceanic applications.
Mi, Hao-Yang; Jing, Xin; Yu, Emily; McNulty, Jason; Turng, Lih-Sheng
2015-12-01
Triple layered small diameter vascular scaffolds, which consisted of thermoplastic polyurethane (TPU) and silk, were fabricated in this study for the first time by combining electrospinning, braiding, and thermally induced phase separation methods. These novel vascular scaffolds, which possess three layers of different structures (nanofibrous inner layer, woven silk filament middle layer, and porous outer layer) have a desired toe region in the tensile test and sufficient suture retention and burst pressure for vascular graft applications. The endothelia cell culture tests showed that a cell layer could form on the inner surface of a scaffold with high cell viability. Furthermore, the cells showed favorable morphology on the scaffold.
Fang, Wen-Zhen; Zhang, Hu; Chen, Li; Tao, Wen-Quan
2015-01-01
In this paper, a multiple-relaxation-time lattice Boltzmann model with an off-diagonal collision matrix was adopted to predict the effective thermal conductivities of the anisotropic heterogeneous materials whose components are also anisotropic. The half lattice division scheme was adopted to deal with the internal boundaries to guarantee the heat flux continuity at the interfaces. Accuracy of the model was confirmed by comparisons with benchmark results and existing simulation data. The present method was then adopted to numerically predict the transverse and longitudinal effective thermal conductivities of three-dimensional (3D) four-directional braided composites. Some corresponding experiments based on the Hot Disk method were conducted to measure their transverse and longitudinal effective thermal conductivities. The predicted data fit the experiment data well. Influences of fiber volume fractions and interior braiding angles on the effective thermal conductivities of 3D four-directional braided composit...
Development of hybrid braided composite rods for reinforcement and health monitoring of structures.
Rana, Sohel; Zdraveva, Emilija; Pereira, Cristiana; Fangueiro, Raul; Correia, A Gomes
2014-01-01
In the present study, core-reinforced braided composite rods (BCRs) were developed and characterized for strain sensing capability. A mixture of carbon and glass fibre was used in the core, which was surrounded by a braided cover of polyester fibres. Three compositions of core with different carbon fibre/glass fibre weight ratios (23/77, 47/53, and 100/0) were studied to find out the optimum composition for both strain sensitivity and mechanical performance. The influence of carbon fibre positioning in BCR cross-section on the strain sensing behaviour was also investigated. Strain sensing property of BCRs was characterized by measuring the change in electrical resistance with flexural strain. It was observed that BCRs exhibited increase (positive response) or decrease (negative response) in electrical resistance depending on carbon fibre positioning. The BCR with lowest amount of carbon fibre was found to give the best strain sensitivity as well as the highest tensile strength and breaking extension. The developed BCRs showed reversible strain sensing behaviour under cyclic flexural loading with a maximum gauge factor of 23.4 at very low strain level (0.55%). Concrete beams reinforced with the optimum BCR (23/77) also exhibited strain sensing under cyclic flexural strain, although the piezoresistive behaviour in this case was irreversible. PMID:24574867
Bell, C. M.; Suárez, M.
1995-01-01
The La Ternera Formation is a thick (>2,100 m) succession of terrigenous clastic sediments, with andesitic and basaltic intercalations, exposed in the Quebrada de Paipote area of the Atacama Region, northern Chile. The strata were deposited in an active rift basin during Late Triassic to (?) Early Jurassic times. The lower 1,000 m of the studied elastic succession comprises pebbly granule paraconglomerates, unconformably overlying Upper Paleozoic sedimentary successions, volcanics, and granitoids. These sediments were derived from the east and are interpreted as braid-plain deposits. The upper 800 m of the succession comprises interbedded orthoconglomerates, sandstones and mudstones. Abundant plant fossils include trees in growth position and carbonaceous horizons. Small scale depositional cycles were the product of migrating braided-river channel systems. Larger scale successions resulted from tectonic uplift. The sediments of the La Ternera Formation were derived predominantly from a tectonically uplifted area of Upper Paleozoic acidic volcanic and plutonic rocks (Pantanoso Formation, Choiyoi Group). Active uplift on the eastern margin of the sedimentary basin probably occurred along north-south trending faults. Continued subsidence of the basin resulted in a Sinemurian to Bajocian marine transgression. Occurrences of Triassic andesitic and basaltic volcanic rocks both to the west and the east of the La Ternera formation suggest deposition in an intea-volcanic graben or half-graben.
TOPICAL REVIEW: Braided affine geometry and q-analogs of wave operators
Gurevich, Dimitri; Saponov, Pavel
2009-08-01
The main goal of this review is to compare different approaches to constructing the geometry associated with a Hecke type braiding (in particular, with that related to the quantum group Uq(sl(n))). We place emphasis on the affine braided geometry related to the so-called reflection equation algebra (REA). All objects of such a type of geometry are defined in the spirit of affine algebraic geometry via polynomial relations on generators. We begin by comparing the Poisson counterparts of 'quantum varieties' and describe different approaches to their quantization. Also, we exhibit two approaches to introducing q-analogs of vector bundles and defining the Chern-Connes index for them on quantum spheres. In accordance with the Serre-Swan approach, the q-vector bundles are treated as finitely generated projective modules over the corresponding quantum algebras. Besides, we describe the basic properties of the REA used in this construction and compare different ways of defining q-analogs of partial derivatives and differentials on the REA and algebras close to them. In particular, we present a way of introducing a q-differential calculus via Koszul type complexes. The elements of the q-calculus are applied to defining q-analogs of some relativistic wave operators.
Development of hybrid braided composite rods for reinforcement and health monitoring of structures.
Rana, Sohel; Zdraveva, Emilija; Pereira, Cristiana; Fangueiro, Raul; Correia, A Gomes
2014-01-01
In the present study, core-reinforced braided composite rods (BCRs) were developed and characterized for strain sensing capability. A mixture of carbon and glass fibre was used in the core, which was surrounded by a braided cover of polyester fibres. Three compositions of core with different carbon fibre/glass fibre weight ratios (23/77, 47/53, and 100/0) were studied to find out the optimum composition for both strain sensitivity and mechanical performance. The influence of carbon fibre positioning in BCR cross-section on the strain sensing behaviour was also investigated. Strain sensing property of BCRs was characterized by measuring the change in electrical resistance with flexural strain. It was observed that BCRs exhibited increase (positive response) or decrease (negative response) in electrical resistance depending on carbon fibre positioning. The BCR with lowest amount of carbon fibre was found to give the best strain sensitivity as well as the highest tensile strength and breaking extension. The developed BCRs showed reversible strain sensing behaviour under cyclic flexural loading with a maximum gauge factor of 23.4 at very low strain level (0.55%). Concrete beams reinforced with the optimum BCR (23/77) also exhibited strain sensing under cyclic flexural strain, although the piezoresistive behaviour in this case was irreversible.
Development of Hybrid Braided Composite Rods for Reinforcement and Health Monitoring of Structures
Directory of Open Access Journals (Sweden)
Sohel Rana
2014-01-01
Full Text Available In the present study, core-reinforced braided composite rods (BCRs were developed and characterized for strain sensing capability. A mixture of carbon and glass fibre was used in the core, which was surrounded by a braided cover of polyester fibres. Three compositions of core with different carbon fibre/glass fibre weight ratios (23/77, 47/53, and 100/0 were studied to find out the optimum composition for both strain sensitivity and mechanical performance. The influence of carbon fibre positioning in BCR cross-section on the strain sensing behaviour was also investigated. Strain sensing property of BCRs was characterized by measuring the change in electrical resistance with flexural strain. It was observed that BCRs exhibited increase (positive response or decrease (negative response in electrical resistance depending on carbon fibre positioning. The BCR with lowest amount of carbon fibre was found to give the best strain sensitivity as well as the highest tensile strength and breaking extension. The developed BCRs showed reversible strain sensing behaviour under cyclic flexural loading with a maximum gauge factor of 23.4 at very low strain level (0.55%. Concrete beams reinforced with the optimum BCR (23/77 also exhibited strain sensing under cyclic flexural strain, although the piezoresistive behaviour in this case was irreversible.
Digital Repository Service at National Institute of Oceanography (India)
AvinashKumar; Jayappa, K.S.; Vethamony, P.
(IDW) interpolation model has been generated and evaluated possible flooding on the estuarine shoals and braided islands, due to heavy rainfall and/or sea-level rise. The model reveals that the possibility of flooding will be higher for those islands...
Directory of Open Access Journals (Sweden)
Mohamed O. E. Altahir
2014-08-01
Full Text Available The aim of this study was to assess the effect of heat treatment and salt concentrations (0, 5, and 10% on the free amino acids (FAA composition of Sudanese braided cheese (BC ripened for up to 3 months at 5±2°C. Heat and salt concentration significantly affected the FAA of braided cheese. The free amino acids concentrations of BC ripened in 0%, 5%, and 10% salted whey (SW were significantly fluctuated. Under ripening conditions tested (salt level + time, braided cheese made from pasteurized milk (BCPM had consistently lower values of FAA than braided cheese made from raw milk (BCRM. In fresh cheese, the major FAA in BCRM were Glu (36.12 nmol/ml, Leu (26.77nmol/ml and Lys (14.51 nmol/ml while the major ones in BCPM were Lys (2.94 nmol/ml and Ala (2.45 nmol/ml. BCPM stored in 10% SW had shorter quality life compared to that stored in 5% salted whey.
Métivier, François; Devauchelle, Olivier; Chauvet, Hugo; Lajeunesse, Eric; Meunier, Patrick; Blanckaert, Koen; Ashmore, Peter; Zhang, Zhi; Fan, Yuting; Liu, Youcun; Dong, Zhibao; Ye, Baisheng
2016-03-01
The Bayanbulak Grassland, Tianshan, P. R. China, is located in an intramontane sedimentary basin where meandering and braided gravel-bed rivers coexist under the same climatic and geological settings. We report and compare measurements of the discharge, width, depth, slope and grain size of individual threads from these braided and meandering rivers. Both types of threads share statistically indistinguishable regime relations. Their depths and slopes compare well with the threshold theory, but they are wider than predicted by this theory. These findings are reminiscent of previous observations from similar gravel-bed rivers. Using the scaling laws of the threshold theory, we detrend our data with respect to discharge to produce a homogeneous statistical ensemble of width, depth and slope measurements. The statistical distributions of these dimensionless quantities are similar for braided and meandering threads. This suggests that a braided river is a collection of intertwined threads, which individually resemble those of meandering rivers. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the threads to be wider than predicted by the threshold theory.
Directory of Open Access Journals (Sweden)
Ziliang Liu
Full Text Available A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km. The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front
Institute of Scientific and Technical Information of China (English)
XIA JunQiang; WU BaoSheng; WANG YanPing; ZHAO ShouGang
2008-01-01
The channel adjustment in a braided reach is very prominent in the fluvial processes of the Lower Yellow River, in which the process of bank erosion plays an important role, especially during the period of clear water scouring. The process of bank erosion is closely related to soil composition and mechanical properties of the riverbanks. In this paper, the recent bank erosion process in a braided reach between Huayuankou and Gaocun was firstly investigated after the water impoundment and sediment detention of the Xiaolangdi Reservoir, and then a field observation and indoor soil tests were conducted at 10 typical riverbanks in the braided reach. Through analyzing the experimental results, changes of riverbank-soil composition and mechanical properties were found, and the two real reasons causing serious bank erosion in the braided reach were identified. The following conclusions were drawn from this study: (i) the majority of riverbanks are made up of cohesive soil, and can be characterized by obvious vertical stratification structures of soil composition; (ii) these riverbanks are very erodible due to the lower clay-content and weak erosion-resistant strength in the bank soil, with its critical shear stress value (0.1-0.3 Pa) being much less than that of the average near-bank flow shear stress (2.0-3.0 Pa), which is one important reason causing serious bank erosion; (iii) frequent occurrence of bank failure during flood seasons usually results from the fact that the values of shear strength parameters such as the cohesion and internal friction angle decrease with the increase of water content in riverbank soil, and the value of cohesion reduces drastically from 34 to 4 kPa with the increase of water content, which is another important reason causing serious bank erosion in the braided reach.
Directory of Open Access Journals (Sweden)
McVeigh Elliot R
2009-08-01
Full Text Available Abstract Background Catheter visualization and tracking remains a challenge in interventional MR. Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency waves. We developed a new "active" catheter design for interventional MR with mechanical performance resembling braided X-ray devices. Our 75 cm long hybrid catheter shaft incorporates a wire lattice in a polymer matrix, and contains three distal loop coils in a flexible and torquable 7Fr device. We explored the impact of braid material designs on radiofrequency and mechanical performance. Results The incorporation of copper wire into in a superelastic nitinol braided loopless antenna allowed good visualization of the whole shaft (70 cm in vitro and in vivo in swine during real-time MR with 1.5 T scanner. Additional distal tip coils enhanced tip visibility. Increasing the copper:nitinol ratio in braiding configurations improved flexibility at the expense of torquability. We found a 16-wire braid of 1:1 copper:nitinol to have the optimum balance of mechanical (trackability, flexibility, torquability and antenna (signal attenuation properties. With this configuration, the temperature increase remained less than 2°C during real-time MR within 10 cm horizontal from the isocenter. The design was conspicuous in vitro and in vivo. Conclusion We have engineered a new loopless antenna configuration that imparts interventional MR catheters with satisfactory mechanical and imaging characteristics. This compact loopless antenna design can be generalized to visualize the whole shaft of any general-purpose polymer catheter to perform safe interventional procedures.
Canonical quantization and braid invariance of (2+1)-dimensional gravity coupled to point particles
Kabat, D; Kabat, Daniel; Ortiz, Miguel
1994-01-01
We investigate the canonical quantization of gravity coupled to pointlike matter in 2+1 dimensions. Starting from the usual point particle action in the first order formalism, we introduce auxiliary variables which make the action locally Poincar\\'e invariant. A Hamiltonian analysis shows that the gauge group is actually larger than the Poincar\\'e group -- certain additional gauge constraints are present which act on the matter degrees of freedom. These additional constraints are necessary to mimic the diffeomorphism invariance present if the theory is formulated with a spacetime metric. The additional gauge constraints are realized projectively in the quantum theory, with a phase in the composition law for finite gauge transformations. That phase is responsible for the braid invariance of physical observables (holonomies).
Braid group representations and cold Fermi gases in the fast pairing regime
Hotalen, Bryan
2015-01-01
It is widely recognized that the main difficulty in designing devices which could process information using quantum states is due to the decoherence of local excitations about a ground state. A solution to this problem was suggested in \\cite{Kitaev}, relying on (non-local) topological excitations, structurally protected against local noise. However, a practical implementation of this proposal using special Landau levels in fractional quantum Hall effect systems (FQHE) \\cite{QHE} has proven elusive, while accessible FQHE states are theoretically not optimal because their representations in the Hilbert space of states are not dense. We propose using a different physical system (cold Fermi atoms), whose semiclassical dynamics is described by a hyperelliptic function in the Sklyanin formalism. The homological structure of the complex curve corresponds to representations of the braid group, with the action of Hecke operators leading to singularities detectable in the semiclassical oscillations. We argue that, for ...
The Brauer Group of Central Separable Monoids in a Braided Monoidal Category
Institute of Scientific and Technical Information of China (English)
J.M. Fernández Vilaboa; R. González Rodríguez; E. Villanueva Novoa
2002-01-01
For a braided monoidal category (C,(○×), K, c), in a previous paper, we construct a Brauer group B1,c(C) for the 1-Azumaya monoids in C. In this paper,we investigate separability and centrality properties for 1-Azumaya monoids when the coequalizers in C are stable. This leads to the notion of 2-Azumaya monoids,and to a new subgroup B2,c(C) of the Brauer group B1,c(C) that generalizes the analogous groups in the symmetric case. Finally, we prove that B2,c(C) and B1,c(C) are equal if the base object of the category is projective.
The algebraic Bethe ansatz for rational braid-monoid lattice models
Martins, M J
1997-01-01
In this paper we study isotropic integrable systems based on the braid-monoid algebra. These systems constitute a large family of rational multistate vertex models and are realized in terms of the B_n, C_n and D_n Lie algebra and by the superalgebra Osp(n|2m). We present a unified formulation of the quantum inverse scattering method for many of these lattice models. The appropriate fundamental commutation rules are found, allowing us to construct the eigenvectors and the eigenvalues of the transfer matrix associated to the B_n, C_n, D_n, Osp(2n-1|2), Osp(2|2n-2), Osp(2n-2|2) and Osp(1|2n) models. The corresponding Bethe Ansatz equations can be formulated in terms of the root structure of the underlying algebra.
Littell, Justin D.
2013-01-01
Increasingly, carbon composite structures are being used in aerospace applications. Their highstrength, high-stiffness, and low-weight properties make them good candidates for replacing many aerospace structures currently made of aluminum or steel. Recently, many of the aircraft engine manufacturers have developed new commercial jet engines that will use composite fan cases. Instead of using traditional composite layup techniques, these new fan cases will use a triaxially braided pattern, which improves case performance. The impact characteristics of composite materials for jet engine fan case applications have been an important research topic because Federal regulations require that an engine case be able to contain a blade and blade fragments during an engine blade-out event. Once the impact characteristics of these triaxial braided materials become known, computer models can be developed to simulate a jet engine blade-out event, thus reducing cost and time in the development of these composite jet engine cases. The two main problems that have arisen in this area of research are that the properties for these materials have not been fully determined and computationally efficient computer models, which incorporate much of the microscale deformation and failure mechanisms, are not available. The research reported herein addresses some of the deficiencies present in previous research regarding these triaxial braided composite materials. The current research develops new techniques to accurately quantify the material properties of the triaxial braided composite materials. New test methods are developed for the polymer resin composite constituent and representative composite coupons. These methods expand previous research by using novel specimen designs along with using a noncontact measuring system that is also capable of identifying and quantifying many of the microscale failure mechanisms present in the materials. Finally, using the data gathered, a new hybrid
Institute of Scientific and Technical Information of China (English)
CAI Gan-wei; WANG Xiang; WANG Ru-gui; LI Zhao-jun; ZHANG Xiao-bin; CANG Ping-ping
2005-01-01
A motor-driven linkage system with links fabricated from 3-dimensional braided composite materials was studied. A group of coupling dynamic equations of the system, including composite materials parameters, electromagnetism parameters of the motor and structural parameters of the link mechanism, were established by finite element method. Based on the air-gap field of non-uniform airspace of three-phase alternating current motor caused by the vibration eccentricity of rotor, the relation of electromechanical coupling at the actual running state was analyzed. And the motor element, which defines the transverse vibration and torsional vibration of the motor as its nodal displacement, was established. Then, based on the damping element model and the expression of energy dissipation of the 3-dimentional braided composite materials, the damping matrix of the system was established by calculating each order modal damping of the mechanism.
DEFF Research Database (Denmark)
Bashforth, Arden Roy; Falcon-Lang, Howard J; Gibling, Martin R
2010-01-01
sedimentary facies comprise the deposits of large braided streams that dissected extensive wetlands containing large lakes. Quadrat analysis of 93 mostly (par)autochthonous mega¿oral assemblages indicates that pteridosperms and ferns dominated communities, with three taxa (Pecopteris spp., Callipteridium....... At the landscape scale, ecological gradients are evident from multivariate analyses of quadrats in a facies context. Pteridosperms dominated marginal wetlands adjacent to steep basin margins. A greater proportion of ferns occurred in or adjacent to braided channel belts, consistent with their opportunistic growth...... and proli¿c reproductive capacity, characteristics advantageous in frequently disturbed habitats. In inter¿uve wetlands distant from channel in¿uence, communities consisted of low-diversity or monospeci¿c patches of slow-growing pteridosperms enclosed in a fern-dominated matrix. Pteridosperms in inter...
Discharge estimates on a small braided river based on synthetic SWOT measurements
Paiva, R. C.; Durand, M. T.; Schubert, J.; Sanders, B. F.; Andreadis, K.
2013-12-01
This research focuses on the feasibility of estimating discharge in a small braided river, the Platte in Nebraska, USA, using synthetic measurements from the upcoming Surface Water and Ocean Topography (SWOT) satellite mission. The SWOT mission is designed to provide observations of surface water elevations (WSE) together with its spatio-temporal derivatives and inundated area. Discharge is subsequently estimated by fitting a 1D diffusive wave discharge formula to SWOT-derived river attributes including WSE, river width (W) and slope (S) using the Metropolis-Hastings algorithm, a Monte-Carlo Markov-Chain (MCMC) method. This involves the estimation of two parameters, the river roughness coefficient (η) and low-flow cross-sectional area (A0). A two-dimensional (2D) hydrodynamic model (BreZo) was applied to a 10 km reach of the Platte to produce synthetic SWOT measurements at a river resolution of approximately 3 m and for a period of 48 hours, during which a small flood progressed through the reach. BreZo was parameterized from a 1 m resolution Digital Terrain Model derived from an aerial lidar collected during low flow conditions, thus capturing many small scale morphological features, and was forced by discharge observations at a USGS gauging station located at the upstream boundary of the reach. This approach offers a level of detail in WSE variability that has previously been absent from SWOT discharge estimation studies, including riffle-pool morphological structures, and thus represents a rigorous test of the discharge estimation methodology. To estimate discharge from BreZo output, the Platte was split into 3 km reaches and output was sampled every four hours. WSE and S were averaged for each reach while W was estimated as the ratio between inundated area and reach length. Uncertainty of these variables was assumed as 10 cm, 1 cm/km and 15%, respectively. Generally, estimated η and A0 values were close to the modeled values and discharge estimates agreed
Williams, R. D.; J. Brasington; Hicks, M; Measures, R.; Rennie, C.D.; Vericat, D.
2013-01-01
Gravel-bed braided rivers are characterized by shallow, branching flow across low relief, complex, and mobile bed topography. These conditions present a major challenge for the application of higher dimensional hydraulic models, the predictions of which are nevertheless vital to inform flood risk and ecosystem management. This paper demonstrates how high-resolution topographic survey and hydraulic monitoring at a density commensurate with model discretization can be used to advance hydrodynam...
Podolak, Charles J.
2013-01-01
An ensemble of rule-based models was constructed to assess possible future braided river planform configurations for the Toklat River in Denali National Park and Preserve, Alaska. This approach combined an analysis of large-scale influences on stability with several reduced-complexity models to produce the predictions at a practical level for managers concerned about the persistence of bank erosion while acknowledging the great uncertainty in any landscape prediction. First, a model of confluence angles reproduced observed angles of a major confluence, but showed limited susceptibility to a major rearrangement of the channel planform downstream. Second, a probabilistic map of channel locations was created with a two-parameter channel avulsion model. The predicted channel belt location was concentrated in the same area as the current channel belt. Finally, a suite of valley-scale channel and braid plain characteristics were extracted from a light detection and ranging (LiDAR)-derived surface. The characteristics demonstrated large-scale stabilizing topographic influences on channel planform. The combination of independent analyses increased confidence in the conclusion that the Toklat River braided planform is a dynamically stable system due to large and persistent valley-scale influences, and that a range of avulsive perturbations are likely to result in a relatively unchanged planform configuration in the short term.
Using Remote-sensing to Survey Topography and Morphologic Change on Large Braided River Beds
Maurice, D.; Hicks, M.; Shankar, U.
2007-12-01
Since 1999 we have made extensive use of a variety of remote-sensing technologies to survey bed topography over reaches of large braided gravel-bed rivers on the east coast of New Zealand's South Island. The motivations have been (i) to collect input and validation data for 2-d hydrodynamic models for quantifying in-stream physical habitat and for predicting flood levels and (ii) to survey spatially-distributed riverbed erosion and deposition in order to estimate bedload fluxes by the 'morphological' method. Typical applications have been to river reaches 3-4 km long and 1 km wide, with grid cells from 1-5 m. We use different techniques to survey dry and wet areas of braided riverbed. For dry areas, we have used digital photogrammetry and infra-red airborne LiDAR. For wetted channels, we have generally used ortho-rectified colour imagery or multi-spectral scanning to map water depth, then we map bed topography by subtracting the water depth from a DEM of the water surface obtained from photogrammetry or LiDAR. The imagery is calibrated to water depth using field measurements on the day of imagery acquisition. Surveys are undertaken during low flows to maximise bed exposure. We use ground-based RTK-GPS and echo-sounding to collect calibration and validation data, and sometimes simply use these methods to survey the wetted areas. Orthoimagery at multiple river flows is used to validate 2-d model results. We have been able to achieve elevation accuracies at interpolated points of the order of 10-15 cm for dry areas. This accuracy typically degrades to 20-30 cm for wetted areas. Our experience has exposed a number of issues relating to survey accuracy and practicality at large river scales. These include: changing geoidal models between surveys; local systematic error with photogrammetric model mosaics; geospatial synchronisation of multi-platform data; time-synchronisation of LiDAR and imagery- collecting aeroplanes and suitable weather and river conditions
Modeling the topography of shallow braided rivers using Structure-from-Motion photogrammetry
Javernick, L.; Brasington, J.; Caruso, B.
2014-05-01
Recent advances in computer vision and image analysis have led to the development of a novel, fully automated photogrammetric method to generate dense 3d point cloud data. This approach, termed Structure-from-Motion or SfM, requires only limited ground-control and is ideally suited to imagery obtained from low-cost, non-metric cameras acquired either at close-range or using aerial platforms. Terrain models generated using SfM have begun to emerge recently and with a growing spectrum of software now available, there is an urgent need to provide a robust quality assessment of the data products generated using standard field and computational workflows. To address this demand, we present a detailed error analysis of sub-meter resolution terrain models of two contiguous reaches (1.6 and 1.7 km long) of the braided Ahuriri River, New Zealand, generated using SfM. A six stage methodology is described, involving: i) hand-held image acquisition from an aerial platform, ii) 3d point cloud extraction modeling using Agisoft PhotoScan, iii) georeferencing on a redundant network of GPS-surveyed ground-control points, iv) point cloud filtering to reduce computational demand as well as reduce vegetation noise, v) optical bathymetric modeling of inundated areas; and vi) data fusion and surface modeling to generate sub-meter raster terrain models. Bootstrapped geo-registration as well as extensive distributed GPS and sonar-based bathymetric check-data were used to quantify the quality of the models generated after each processing step. The results obtained provide the first quantified analysis of SfM applied to model the complex terrain of a braided river. Results indicate that geo-registration errors of 0.04 m (planar) and 0.10 m (elevation) and vertical surface errors of 0.10 m in non-vegetation areas can be achieved from a dataset of photographs taken at 600 m and 800 m above the ground level. These encouraging results suggest that this low-cost, logistically simple method can
Littell, Justin D.; Binienda, Wieslaw K.; Arnold, William A.; Roberts, Gary d.; Goldberg, Robert K.
2008-01-01
In previous work, the ballistic impact resistance of triaxial braided carbon/epoxy composites made with large flat tows (12k and 24k) was examined by impacting 2 X2 X0.125" composite panels with gelatin projectiles. Several high strength, intermediate modulus carbon fibers were used in combination with both untoughened and toughened matrix materials. A wide range of penetration thresholds were measured for the various fiber/matrix combinations. However, there was no clear relationship between the penetration threshold and the properties of the constituents. During some of these experiments high speed cameras were used to view the failure process, and full-field strain measurements were made to determine the strain at the onset of failure. However, these experiments provided only limited insight into the microscopic failure processes responsible for the wide range of impact resistance observed. In order to investigate potential microscopic failure processes in more detail, quasi-static tests were performed in tension, compression, and shear. Full-field strain measurement techniques were used to identify local regions of high strain resulting from microscopic failures. Microscopic failure events near the specimen surface, such as splitting of fiber bundles in surface plies, were easily identified. Subsurface damage, such as fiber fracture or fiber bundle splitting, could be identified by its effect on in-plane surface strains. Subsurface delamination could be detected as an out-of-plane deflection at the surface. Using this data, failure criteria could be established at the fiber tow level for use in analysis. An analytical formulation was developed to allow the microscopic failure criteria to be used in place of macroscopic properties as input to simulations performed using the commercial explicit finite element code, LS-DYNA. The test methods developed to investigate microscopic failure will be presented along with methods for determining local failure criteria
Demissie, Biadgilgn; Frankl, Amaury; Haile, Mitiku; Nyssen, Jan
2014-05-01
Braided rivers have received relatively little attention in research and development activities in drylands. However, they strongly impact agroecology and agricultural activities and thereby local livelihoods. The Raya Graben (3750 km² including the escarpment) is a marginal graben of the Ethiopian Rift Valley located in North Ethiopia. In order to study the dynamics of braided rivers and the relationship with biophysical controls, 20 representative catchments were selected, ranging between 15 and 311 km². First, the 2005 morphology (length, area) of the braided rivers was related to biophysical controls (vegetation cover, catchment area and slope gradient in the steep upper catchments and gradient in the graben bottom). Second, the changes in length of the braided rivers were related to vegetation cover changes in the upper catchments since 1972. Landsat imagery was used to calculate the Normalized Difference Vegetation Index (NDVI), and to map vegetation cover and the total length of the braided rivers. Spot CNES imagery available from Google Earth was used to identify the total area of the braided rivers in 2005. A linear regression analysis revealed that the length of braided rivers was positively related to the catchment area (R²=0.32, p<0.01), but insignificantly related to vegetation cover in the upper catchments. However, there is an indication that it is an important factor in the relationship calculated for 2005 (R²=0.2, p=0.064). Similarly, the area occupied by the braided rivers was related to NDVI (R²=0.24, p<0.05) and upper catchment area (R²=0.447, p<0.01). Slope gradient is not an important explanatory factor. This is related to the fact that slope gradients are steep (average of 38.1%) in all upper and gentle (average of 3.4%) in graben bottom catchments. The vegetation cover in the upper catchments shows a statistically insignificant increasing trend (R²=0.73, p=0.067) over the last 40 years, whereas length of rivers in the graben bottom
Evaluation of Test Methods for Triaxially Braided Composites using a Meso-Scale Finite Element Model
Energy Technology Data Exchange (ETDEWEB)
Zhang, Chao
2015-10-01
The characterization of triaxially braided composite is complicate due to the nonuniformity of deformation within the unit cell as well as the possibility of the freeedge effect related to the large size of the unit cell. Extensive experimental investigation has been conducted to develop more accurate test approaches in characterizing the actual mechanical properties of the material we are studying. In this work, a meso-scale finite element model is utilized to simulate two complex specimens: notched tensile specimen and tube tensile specimen, which are designed to avoid the free-edge effect and free-edge effect induced premature edge damage. The full field strain data is predicted numerically and compared with experimental data obtained by Digit Image Correlation. The numerically predicted tensile strength values are compared with experimentally measured results. The discrepancy between numerically predicted and experimentally measured data, the capability of different test approaches are analyzed and discussed. The presented numerical model could serve as assistance to the evaluation of different test methods, and is especially useful in identifying potential local damage events.
Tremblay, Jaëlle; Mac-Thiong, Jean-Marc; Brailovski, Vladimir; Petit, Yvan
2015-09-01
This study investigates the use of braided tubular superelastic cables, previously used for sternum closure following sternotomy, as sublaminar fixation method. It compares the biomechanical performance of spinal instrumentation fixation systems with regular sublaminar cables and proprietary superelastic cables. A hybrid experimental protocol was applied to six porcine L1-L4 spinal segments to compare multifilament sublaminar cables (Atlas, Medtronic Sofamor Danek, Memphis, TN) with proprietary superelastic cables. First, intact total range of motion was determined for all specimens using pure moment loading. Second, pure moments were imposed to the instrumented specimens until these intact total ranges of motion were reproduced. Compared to the intact specimens, the use of superelastic cables resulted in stiffer instrumented specimens than the use of multifilament cables for all the loading modes except axial torsion. Consequently, the superelastic cables limited the instrumented segments mobility more than the multifilament cables. Spinal instrumentation fixation systems using superelastic cables could be a good alternative to conventional sublaminar cables as it maintains a constant stabilization of the spine during loading.
The classification of the virtually cyclic subgroups of the sphere braid groups
Gonçalves, Daciberg Lima
2011-01-01
We study the problem of determining the isomorphism classes of the virtually cyclic subgroups of the n-string braid groups B_n(S^2) of the 2-sphere S^2. If n is odd, or if n is even and sufficiently large, we obtain the complete classification. For small even values of n, the classification is complete up to an explicit finite number of open cases. In order to prove our main theorem, we obtain a number of other results of independent interest, notably the characterisation of the centralisers and normalisers of the finite cyclic and dicyclic subgroups of B_n(S^2), a result concerning conjugate powers of finite order elements, an analysis of the isomorphism classes of the amalgamated products that occur as subgroups of B_n(S^2), as well as an alternative proof of the fact that the universal covering space of the n-th configuration space of S^2 has the homotopy type of S^3 if n is greater than or equal to three.
3D flexible NiTi-braided elastomer composites for smart structure applications
Heller, L.; Vokoun, D.; Šittner, P.; Finckh, H.
2012-04-01
While outstanding functional properties of thin NiTi wires are nowadays well recognized and beneficially utilized in medical NiTi devices, development of 2D/3D wire structures made out of these NiTi wires remains challenging and mostly unexplored. The research is driven by the idea of creating novel 2D/3D smart structures which inherit the functional properties of NiTi wires and actively utilize geometrical deformations within the structure to create new/improved functional properties. Generally, textile technology provides attractive processing methods for manufacturing 2D/3D smart structures made out of NiTi wires. Such structures may be beneficially combined with soft elastomers to create smart deformable composites. Following this route, we carried out experimental work focused on development of 3D flexible NiTi-braided elastomer composites involving their design, laboratory manufacture and thermomechanical testing. We describe the manufacturing technology and structural properties of these composites; and perform thermomechanical tests on the composites, focusing particularly on quasistatic tensile properties, energy absorption, damping and actuation under tensile loading. Functional thermomechanical properties of the composites are discussed with regard to the mechanical properties of the components and architecture of the composites. It is found that the composites indeed inherit all important features of the thermomechanical behavior of NiTi wires but, due to their internal architecture, outperform single NiTi wires in some features such as the magnitude of recoverable strain, superelastic damping capacity and thermally induced actuation strain.
Braided rivers, lakes and sabkhas of the upper Triassic Cifuncho formation, Atacama region, Chile
Suárez, M.; Bell, C. M.
1994-01-01
A 1,000-m-thickness of Upper Triassic (to possibly Hettangian) sediments of the Cifuncho Formation are exposed in the coastal Cordillera of the Atacama Region, Chile. These coarse-grained clastic terrigenous strata are interpreted as the deposits of braided rivers, ephemeral lakes, sabkhas and volcaniclastic alluvial fans. They include conglomerates, pebbly sandstones, fine to medium-grained sandstones and thin, finely-laminated limestones. Halite hopper-casts are abundant in sandstones near the top of the section. Approximately 90% of the clastic detritus was derived from an upper Paleozoic metasedimentary accretionary complex located to the west. Andesitic debris flow and pyroclastic flow deposits occur near the base of the sequence. Isolated tuff intercalations and an ignimbritic lava flow occur higher in the section. The great thickness of coarse-grained and ill-sorted clastic sediments suggests deposition in an actively subsiding basin, probably a graben, adjacent to rising highlands. Overlying Hettangian-Sinemurian marine sediments were deposited by a transgression which occurred during a world-wide lowstand. This suggests that thermal subsidence followed the Triassic rifting.
BRAID: A Unifying Paradigm for the Analysis of Combined Drug Action
Twarog, Nathaniel R.; Stewart, Elizabeth; Hammill, Courtney Vowell; A. Shelat, Anang
2016-01-01
With combination therapies becoming increasingly vital to understanding and combatting disease, a reliable method for analyzing combined dose response is essential. The importance of combination studies both in basic and translational research necessitates a method that can be applied to a wide range of experimental and analytical conditions. However, despite increasing demand, no such unified method has materialized. Here we introduce the Bivariate Response to Additive Interacting Doses (BRAID) model, a response surface model that combines the simplicity and intuitiveness needed for basic interaction classifications with the versatility and depth needed to analyze a combined response in the context of pharmacological and toxicological constraints. We evaluate the model in a series of simulated combination experiments, a public combination dataset, and several experiments on Ewing’s Sarcoma. The resulting interaction classifications are more consistent than those produced by traditional index methods, and show a strong relationship between compound mechanisms and nature of interaction. Furthermore, analysis of fitted response surfaces in the context of pharmacological constraints yields a more concrete prediction of combination efficacy that better agrees with in vivo evaluations. PMID:27160857
On the use of airborne LiDAR for braided river monitoring and water surface delineation
Vetter, M.; Höfle, B.; Pfeifer, N.; Rutzinger, M.; Stötter, J.
2009-04-01
Airborne LiDAR is an established technology for Earth surface surveying. With LiDAR data sets it is possible to derive maps with different land use classes, which are important for hydraulic simulations. We present a 3D point cloud based method for automatic water surface delineation using single as well as multitemporal LiDAR data sets. With the developed method it is possible to detect the location of the water surface with high planimetric accuracy. The multitemporal analysis of different LiDAR data sets makes it possible to visualize, monitor and quantify the changes of the flow path of braided rivers as well as derived water surface land use classes. The reflection properties from laser beams (1064 nm wavelength) on water surfaces are characterized by strong absorption or specular reflection resulting in a dominance of low signal amplitude values and a high number of laser shot dropouts (i.e. non-recorded laser echoes). The occurrence of dropouts is driven by (i) the incidence angle, (ii) the surface reflectance and (iii) the roughness of the water body. The input data of the presented delineation method are the modeled dropouts and the point cloud attributes of geometry and signal amplitude. A terrestrial orthophoto is used to explore the point cloud in order to find proper information about the geometry and amplitude attributes that are characteristic for water surfaces. The delineation method is divided into five major steps. (a) We compute calibrated amplitude values by reducing the atmospheric, topographic influences and the scan geometry for each laser echo. (b) Then, the dropouts are modeled by using the information from the time stamps, the pulse repetition frequency, the inertial measurement unit and the GPS information of the laser shots and the airplane. The next step is to calculate the standard deviation of the heights for all reflections and all modeled dropouts (c) in a specific radius around the points. (d) We compute the amplitude ratio
Helical Groundwater Flow in Braided-River Sediments and its Effects on Solute Mixing
Arie Cirpka, Olaf; Bennett, Jeremy Paul; Haslauer, Claus; Ye, Yu; Rolle, Massimo; Chiogna, Gabriele
2016-04-01
Spatially variable orientation of anisotropy can cause helical flow in porous media. In previous studies (Chiogna et al., 2015; Cirpka et al., 2015; see also Figure 1), we analyzed hydraulic conductivity fields with blockwise constant anisotropic correlation structure showing that macroscopically helical flow evolves, and leads to enhanced solute dilution in steady-state advective-dispersive transport. While these studies demonstrated the potential importance of helical flow in heterogeneous porous media, the likelihood of its occurrence remained unclear. In particular, natural sediments do not exhibit extended stripes of materials with diagonally oriented internal anisotropy. In the present study, we generated realistic looking sedimentary structures mimicking scour fills that may be created in braided-river sediments. The individual geobodies are filled with anisotropic porous material. Cross-sections show typical cross-bedding. In particular we analyzed how the variability in bulk hydraulic conductivity between the geobodies and the differences in the orientation of anisotropy affect flow and transverse solute mixing. While the variance of log-hydraulic conductivity controls longitudinal spreading, the variability in the orientation of anisotropy is decisive for folding and mixing perpendicular to the mean flow direction. The importance of non-stationary anisotropy for transverse mixing poses a challenge for the hydraulic characterization of sediments when predicting lengths of mixing-controlled quasi steady-state plumes. References [1] O.A. Cirpka, G. Chiogna, M. Rolle, A. Bellin: Transverse mixing in three-dimensional non-stationary anisotropic heterogeneous porous media. Water Resour. Res. 51(1): 241-260 (2015). [2] G. Chiogna, O.A. Cirpka, M. Rolle, A. Bellin: Helical flow in three-dimensional non-stationary anisotropic heterogeneous porous media. Water Resour. Res. 51(1): 261-280 (2015).
Measures, R.; Hicks, D. M.; Brasington, J.
2016-01-01
Abstract Numerical morphological modeling of braided rivers, using a physics‐based approach, is increasingly used as a technique to explore controls on river pattern and, from an applied perspective, to simulate the impact of channel modifications. This paper assesses a depth‐averaged nonuniform sediment model (Delft3D) to predict the morphodynamics of a 2.5 km long reach of the braided Rees River, New Zealand, during a single high‐flow event. Evaluation of model performance primarily focused upon using high‐resolution Digital Elevation Models (DEMs) of Difference, derived from a fusion of terrestrial laser scanning and optical empirical bathymetric mapping, to compare observed and predicted patterns of erosion and deposition and reach‐scale sediment budgets. For the calibrated model, this was supplemented with planform metrics (e.g., braiding intensity). Extensive sensitivity analysis of model functions and parameters was executed, including consideration of numerical scheme for bed load component calculations, hydraulics, bed composition, bed load transport and bed slope effects, bank erosion, and frequency of calculations. Total predicted volumes of erosion and deposition corresponded well to those observed. The difference between predicted and observed volumes of erosion was less than the factor of two that characterizes the accuracy of the Gaeuman et al. bed load transport formula. Grain size distributions were best represented using two φ intervals. For unsteady flows, results were sensitive to the morphological time scale factor. The approach of comparing observed and predicted morphological sediment budgets shows the value of using natural experiment data sets for model testing. Sensitivity results are transferable to guide Delft3D applications to other rivers. PMID:27708477
International Nuclear Information System (INIS)
Highlights: • The stability of materials under extreme conditions is an important issue for the safety of nuclear reactors. • To improve zircaloys’ thermal stability in off-normal conditions, coating of SiC filaments is considered because silicon carbide possesses remarkable inertness at high temperatures. • Mathematical morphology was used for automatic defect identification in Zircaloy-4 rods braided with the layer of SiC filament. • The original mathematical morphology algorithms allowing solving the problem of quality assurance were developed. • In nuclear industry, such algorithms are used for the first time. - Abstract: In the after-Fukushima world, the stability of materials under extreme conditions is an important issue for the safety of nuclear reactors. Among the methods explored currently to improve zircaloys’ thermal stability in off-normal conditions, using a protective coat of the SiC filaments is considered because silicon carbide is well known for its remarkable chemical inertness at high temperatures. A typical SiC fiber contains ∼50,000 individual filaments of 5–10 μm in diameter. In this paper, an effort was made to develop and apply mathematical morphology to the process of automatic defect identification in Zircaloy-4 rods braided with the protective layer of the silicon carbide filament. However, the issues of the braiding quality have to be addressed to ensure its full protective potential. We present the original mathematical morphology algorithms that allow solving this problem of quality assurance successfully. In nuclear industry, such algorithms are used for the first time, and could be easily generalized to the case of automated continuous monitoring for defect identification in the future
Desbois, Jean; Nechaev, Sergei
1997-01-01
We study numerically and analytically the average length of reduced (primitive) words in so-called locally free and braid groups. We consider the situations when the letters in the initial words are drawn either without or with correlations. In the latter case we show that the average length of the reduced word can be increased or lowered depending on the type of correlation. The ideas developed are used for analytical computation of the average number of peaks of the surface appearing in som...
NEAR-IR Spectroscopy of Young Stars in the Braid Nebula Star Formation Region in Cygnus Ob7
Aspin, Colin; Beck, Tracy L.; Pyo, Tae-Soo; Davis, Chris J.; Schieven, G. M.; Khanzadyan, Tigran; Magakian, Tigran; Movsessian, Tigran; NIkogossian, Elena G.; Mitchison, Sharon; Smith, Michael D.
2008-01-01
We present 1.4 to 2.5 um integral field spectroscopy of 16 stars in the Braid Nebula star formation region in Cygnus OB7. These data forms one aspect of a large-scale multi-wavelength survey aimed at determining an unbiased estimate of the number, mass distribution, and evolutionary state of the young stars within this one square degree area of the previously poorly studied Lynds 1003 molecular cloud. Our new spectroscopic data, when combined with 2MASS near-IR photometry, provide evidence of...
Jules Fleury, Thomas; Pothin, Virginie; Vella, Claude; Dussouillez, Philippe; Izem, Abdelkoddouss
2015-04-01
Low-altitude aerial photogrammetry offers new opportunities for geomorphology and other fields requiring very high-resolution topographic data. It combines the advantages of the reproducibility of GPS topographic surveys with the high accuracy of LIDAR, but at relatively low-cost, easy-to-deploy and with the synaptic advantage of remote sensing. In order to evaluate the potential of photogrammetry on river systems and to assess river-bed changes and erosion-accretion processes, we conducted several surveys over the period of one year on the Buech river, a gravel-bed braided river located in the French Southern Alps. The study area is located directly upstream of a gravel pit and there is an interest in evaluating its effects on the riverbed. Our field protocol was comprised of vertical aerial photographs taken from a microlight aircraft flying approximately 300 ft above the ground. The equipment used was a full-frame DSLR with a wide angle lense, synchronised with a DGPS onboard. Fourty 40cm wide targets were placed on the ground and georeferenced by RTK DGPS with an accuracy of 2cm. In addition, close to one thousand Ground Control Points (GCPs) were measured within the different types of ground surfaces (vegetated, water, gravels) in order to assess the Digital Terrain Model (DTM) accuracy. We operated the production of the 3D model and its derived products: Digital Surface Model (DSM) and orthophotography, with user-friendly Agisoft (c) Photoscan Professional software. The processing of several hundred pictures with 2.5 cm ground resolution resulted in a DSM with a resolution of 10 cm and a vertical accuracy within 5 cm. As is expected, accuracy was best on bare bars and decreased with increasing vegetation density. To complement the DSM in the wetted channels, we used the orthophotos to establish a relationship between water color and flow depth using statistical multivariate regressions. Merging the bathymetric model and the DSM produced a DTM with a vertical
Compressive response and failure of braided textile composites: Experiments and analysis
Quek, Shu Ching
Textile composites have similar mechanical attributes when compared with other fiber reinforced composites, however, because of cost effective manufacturability, they are being considered as a viable alternative for structural applications in the aerospace and automotive industries. This thesis focuses on the compressive response of a 2D flat triaxial braided composite (2DTBC) under conditions that are similar to those encountered when a tubular structural member undergoes axial compressive crush. During crush, the walls of the member are subjected to predominantly biaxial stress state of compression (lengthwise) and tension (widthwise), while, near the end of the tube where the loading is introduced, a combined bending and compression type of biaxial stress state is predominant. Experiments on flat 2DTBCs were carried out under two types of load states: compression/tension (C/T) and bending/compression (B/C). C/T tests were carried out on a special planar biaxial load frame. External loads and full field planar incremental strain fields (the Deltaepsilonx, Deltaepsilon y and Deltagammaxy) were captured during the loading process via digital speckle photography (DSP). Failure mechanisms were investigated and supplemented by post experiment microscopy. Similarly, load and strain data were obtained from the B/C tests, which was based on a novel eccentric Elastica experimental configuration. The experimental results provided fundamental insight into the failure mechanisms of 2DTBCs and motivated the development of robust micromechanics based strength models for the 2DTBCs. In addition, the biaxial experimental data provide grounds for the validation of failure theories that have been conceived on measurements based on uniaxial loading. An analytical model based on constituent properties and textile geometry as input was developed to determine the elastic orthotropic stiffness properties of a 2DTBC. A finite element (FE) based micromechanics model of the 2DTBC was
Preparation and Characterization of Chitosan-Coated Poly(l-Lactic Acid Fibers and Their Braided Rope
Directory of Open Access Journals (Sweden)
Tetsuya Furuike
2015-10-01
Full Text Available Novel chitosan (CS-coated poly(l-lactic acid (PLA fibers (CS–PLA were prepared by reaction of an alkali and CS under heat treatment without a chemical binder. These treatments induced hydrolysis on the PLA surface, formation of ionic bonds between the carboxyl groups of the PLA surface and the amino groups of CS, and dehydration between the carboxyls and amines. The prepared fibers were characterized by scanning electron microscopy and mechanical strength tests. The presence of CS on the fiber surface was observed by the visual test of CS–PLA with amido black 10B and confirmed by the amine ratio obtained by X-ray photoelectron spectroscopy. The coating thickness of CS on the surface of the PLA fibers was approximately 28 nm, as determined from calculations based on the results of Kjeldahl nitrogen analysis and elemental analysis. The degradation properties of CS–PLA were also investigated. These properties were apparently enhanced by hydrophilicity resulting from the CS-coating treatment. Furthermore, braided ropes prepared using CS–PLA became tight with increasing number of core ropes. Results indicate that the objective tensile strength and flexibility of the braided rope could be controlled by adjusting the number of core fibers.
Institute of Scientific and Technical Information of China (English)
QU Zhaoming; WANG Qingguo; LEI Yisan; ZHANG Ruigang
2013-01-01
To develop electromagnetic protection composites with integrated structure-function properties,the three-dimension (3D) braided nickel plated carbon fiber/epoxy resin (Ni-CF3D/EP) composites were prepared based on 3D five-directional braiding,unitary nickel plating and mold compression shaping.The electromagnetic protection properties of Ni-CF3D/EP composites including shielding effectiveness (SE) and reflection loss against plane electromagnetic wave,shielding properties against electromagnetic pulse (EMP) were investigated.The test results show that the novel composites have good electromagnetic protection properties in a wide frequency range of 14 kHz～ 18 GHz with SE of 42 dB～95 dB,the absorption bandwidth of-5 dB in 2 GHz～ 18 GHz can reach 10 GHz and the pulse peak SE against EMP is 43.7 dB which can reduce the electromagnetic energy greatly.Meanwhile,the mechanic properties were also investigated and the results indicate that the Ni-CF3D/EP composites can replace metal materials for loading-bearing structural applications because of their excellent mechanic properties.
Glazoff, Michael V.; Hiromoto, Robert; Tokuhiro, Akira
2014-08-01
In the after-Fukushima world, the stability of materials under extreme conditions is an important issue for the safety of nuclear reactors. Among the methods explored currently to improve zircaloys’ thermal stability in off-normal conditions, using a protective coat of the SiC filaments is considered because silicon carbide is well known for its remarkable chemical inertness at high temperatures. A typical SiC fiber contains ∼50,000 individual filaments of 5-10 μm in diameter. In this paper, an effort was made to develop and apply mathematical morphology to the process of automatic defect identification in Zircaloy-4 rods braided with the protective layer of the silicon carbide filament. However, the issues of the braiding quality have to be addressed to ensure its full protective potential. We present the original mathematical morphology algorithms that allow solving this problem of quality assurance successfully. In nuclear industry, such algorithms are used for the first time, and could be easily generalized to the case of automated continuous monitoring for defect identification in the future.
Institute of Scientific and Technical Information of China (English)
Yong-jun LU; Zhao-yin WANG; Li-qin ZUO; Li-jun ZHU
2005-01-01
The characteristics of water flow and sediment transport in a typical meandering and island-braided reach of the middle Yangtze River is investigated using a two-dimensional (2D)mathematical model. The major problems studied in the paper include the carrying capacity for suspended load, the incipient velocity and transport formula of non-uniform sediment, the thickness of the mixed layer on the riverbed, and the partitioning of bed load and suspended load. The model parameters are calibrated using extensive field data. Water surface profiles, distribution of flow velocities, riverbed deformation are verified with site measurements. The model is applied to a meandering and island-braided section of the Wakouzi-Majiazui reach in the middle Yangtze River,which is about 200 km downstream from the Three Gorges Dam, to study the training scheme of the navigation channels. The model predicts the processes of sediment deposition and river bed erosion,changes of flow stage and navigation conditions for the first 20 years of impoundment of the Three Gorges Project.
Energy Technology Data Exchange (ETDEWEB)
Janke, Christopher James [ORNL; Das, Sadananda [ORNL; Oyola, Yatsandra [ORNL; Mayes, Richard T [ORNL; Gill, Gary [Pacific Northwest National Laboratory (PNNL); Kuo, Li-Jung [Pacific Northwest National Laboratory (PNNL); Wood, Jordana [Pacific Northwest National Laboratory (PNNL)
2015-01-01
This report describes work on the successful completion of Milestone M2FT-15OR0310041 (1/30/2015) entitled, Demonstrate braided material with 3.5 g U/kg sorption capacity under seawater testing condition . This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent braided materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed four braided fiber adsorbents that have demonstrated uranium adsorption capacities greater than 3.5 g U/kg adsorbent after marine testing at PNNL. The braided adsorbents were synthesized by braiding or leno weaving high surface area polyethylene fibers and conducting radiation-induced graft polymerization of itaconic acid and acrylonitrile monomers onto the braided materials followed by amidoximation and base conditioning. The four braided adsorbents demonstrated capacity values ranging from 3.7 to 4.2 g U/kg adsorbent after 56 days of exposure in natural coastal seawater at 20 oC. All data are normalized to a salinity of 35 psu.
Schubert, J.; Sanders, B. F.; Andreadis, K.
2013-12-01
The Surface Water and Ocean Topography (SWOT) mission, currently under study by NASA (National Aeronautics and Space Administration) and CNES (Centre National d'Etudes Spatiales), is designed to provide global spatial measurements of surface water properties at resolutions better than 10 m and with centimetric accuracy. The data produced by SWOT will include irregularly spaced point clouds of the water surface height, with point spacings from roughly 2-50 m depending on a point's location within SWOT's swath. This could offer unprecedented insight into the spatial structure of rivers. Features that may be resolved include backwater profiles behind dams, drawdown profiles, uniform flow sections, critical flow sections, and even riffle-pool flow structures. In the event that SWOT scans a river during a major flood, it becomes possible to delineate the limits of the flood as well as the spatial structure of the water surface elevation, yielding insight into the dynamic interaction of channels and flood plains. The Platte River in Nebraska, USA, is a braided river with a width and slope of approximately 100 m and 100 cm/km, respectively. A 1 m resolution Digital Terrain Model (DTM) of the river basin, based on airborne lidar collected during low-flow conditions, was used to parameterize a two-dimensional, variable resolution, unstructured grid, hydrodynamic model that uses 3 m resolution triangles in low flow channels and 10 m resolution triangles in the floodplain. Use of a fine resolution mesh guarantees that local variability in topography is resolved, and after applying the hydrodynamic model, the effects of topographic variability are expressed as variability in the water surface height, depth-averaged velocity and flow depth. Flow is modeled over a reach length of 10 km for multi-day durations to capture both frequent (diurnal variations associated with regulated flow) and infrequent (extreme flooding) flow phenomena. Model outputs reveal a number of interesting
Wang, Juven C.; Wen, Xiao-Gang
2015-01-01
String and particle braiding statistics are examined in a class of topological orders described by discrete gauge theories with a gauge group G and a 4-cocycle twist ω4 of G 's cohomology group H4(G ,R /Z ) in three-dimensional space and one-dimensional time (3 +1 D ) . We establish the topological spin and the spin-statistics relation for the closed strings and their multistring braiding statistics. The 3 +1 D twisted gauge theory can be characterized by a representation of a modular transformation group, SL (3 ,Z ) . We express the SL (3 ,Z ) generators Sx y z and Tx y in terms of the gauge group G and the 4-cocycle ω4. As we compactify one of the spatial directions z into a compact circle with a gauge flux b inserted, we can use the generators Sx y and Tx y of an SL (2 ,Z ) subgroup to study the dimensional reduction of the 3D topological order C3 D to a direct sum of degenerate states of 2D topological orders Cb2 D in different flux b sectors: C3 D=⊕bCb2 D . The 2D topological orders Cb2 D are described by 2D gauge theories of the group G twisted by the 3-cocycle ω3 (b ), dimensionally reduced from the 4-cocycle ω4. We show that the SL (2 ,Z ) generators, Sx y and Tx y, fully encode a particular type of three-string braiding statistics with a pattern that is the connected sum of two Hopf links. With certain 4-cocycle twists, we discover that, by threading a third string through two-string unlink into a three-string Hopf-link configuration, Abelian two-string braiding statistics is promoted to non-Abelian three-string braiding statistics.
Lin, Jia-Horng; Chen, Chih-Kuang; Wen, Shih-Peng; Lou, Ching-Wen
2015-01-01
Bone scaffolds require a three-dimensional structure, high porosity, interconnected pores, adequate mechanical strengths, and non-toxicity. A high porosity is incongruent with mechanical strengths. Therefore, this study combines a braiding method and microsphere solution to create bone scaffolds with a high porosity and sufficient mechanical strengths. First, poly-L-lactide (PLLA) plied yarns are braided into 5-, 10-, 15-, 20-, and 25-layer hollow braids, and then thermally treated at 165 °C for various durations. Next, sodium alginate (SA) microspheres, cross-linked with CaCl2 solution with various concentrations, are combined with PLLA porous braided bone scaffolds to form PLLA/SA/CS microsphere hybrid scaffolds, which are then observed for surface observation, and tested for porosity, water contact angle, compressive strength, MTT assay, bioactivity, alkaline phosphatase (ALP) assay, cell attachment, and statistical analyses. The test results show that the layer amount of the bone scaffold is proportional to the compressive strength. With the same number of layers, the compressive strength is inversely proportional to the concentration of the CaCl2 solution. The results of surface observation, porosity, and water contact angle tests show that PLLA/SA/CS microsphere hybrid scaffolds possess a high porosity and good hydrophilicity; as a result, the braiding manufacture and the bonding technique effectively solve the confliction between porosity and mechanical strength. The concentration of CaCl2 does not pertain to cell activity and ALP results, exemplified by good cell attachment on bone scaffolds for each specification. PMID:25953547
Dow, Marvin B.; Dexter, H. Benson
1997-01-01
Summary results are presented from the research conducted on woven, braided, knitted and stitched (textile) composites at the Langley Research Center and under the NASA Advanced Composites Technology (ACT) Program in the period from 1985 to 1997. The report also includes an annotated bibliography of 270 U.S. publications on textile composites (with their abstracts). Two major research areas are discussed: (1) the general research in textile composites performed throughout the period under the direction of the Langley Research Center and (2) the development of textile composite aircraft structures by industry under the NASA ACT Program. The annotated bibliography is organized in three subsections: (1) general textiles R&D under the auspices of Langley, (2) ACT Program development of textile structural components, and (3) textiles research by individuals and organizations not associated with the ACT Program. An author index is provided for the reports and documents.
Brasington, J.; Williams, R. D.; Vericat, D.; Hicks, M.; Goodsell, B.
2011-12-01
The last decade has witnessed a technological revolution in the acquisition of geospatial data. These developments have profound implications for the practice of river science, creating a step-change in the dimensionality, resolution and precision of measurement of fluvial forms and processes. The pace of change has been remarkable; typical datasets of channel geometry have grown from cross-sections containing a few hundred survey observations, to airborne lidar surveys incorporating millions of points. With wide-area terrestrial laser scans comprising tens of billions observations now set to emerge, our data perspectives have been expanded by seven orders of magnitude. Such rapid modernization brings with it new challenges and necessitates the development of novel data management strategies, original algorithms to process dense 3d data, higher dimensional spatial metrics and innovative simulation methods to make optimal use of this rich vein of information. In this paper we describe a field-to-product methodology which aims to address these challenges and has been used to generate an unparalleled dataset capturing the morphological evolution of a labile gravel-bed braided river through a continuous sequence of floods between Oct 2009 and May 2010. These data were generated using a data-fusion approach that combines close-range terrestrial laser scanning with bathymetric data derived from non-metric aerial photography. Surveys were acquired over a 2.5 x 0.7 km reach of the Rees River; a piedmont braided system draining a highland catchment of Southern Alps of NZ. During a 10 month field campaign through the summer flood season, this study reach was resurveyed systematically after each competent flood event. Multi-scale DEMs were derived that capture the spatial distribution of facies and morphological changes at high precision. Results indicate that over 80% of the reach was subject to significant erosion or deposition, with a complex pattern of response to the
Sorini, Chris; Chattopadhyay, Aditi; Goldberg, Robert K.; Kohlman, Lee W.
2016-01-01
Understanding the high velocity impact response of polymer matrix composites with complex architectures is critical to many aerospace applications, including engine fan blade containment systems where the structure must be able to completely contain fan blades in the event of a blade-out. Despite the benefits offered by these materials, the complex nature of textile composites presents a significant challenge for the prediction of deformation and damage under both quasi-static and impact loading conditions. The relatively large mesoscale repeating unit cell (in comparison to the size of structural components) causes the material to behave like a structure rather than a homogeneous material. Impact experiments conducted at NASA Glenn Research Center have shown the damage patterns to be a function of the underlying material architecture. Traditional computational techniques that involve modeling these materials using smeared homogeneous, orthotropic material properties at the macroscale result in simulated damage patterns that are a function of the structural geometry, but not the material architecture. In order to preserve heterogeneity at the highest length scale in a robust yet computationally efficient manner, and capture the architecturally dependent damage patterns, a previously-developed subcell modeling approach where the braided composite unit cell is approximated as a series of four adjacent laminated composites is utilized. This work discusses the implementation of the subcell methodology into the commercial transient dynamic finite element code LS-DYNA (Livermore Software Technology Corp.). Verification and validation studies are also presented, including simulation of the tensile response of straight-sided and notched quasi-static coupons composed of a T700/PR520 triaxially braided [0deg/60deg/-60deg] composite. Based on the results of the verification and validation studies, advantages and limitations of the methodology as well as plans for future work
De Vincenzo, Annamaria; Brancati, Francesco; Pannone, Marilena
2016-08-01
Laboratory experiments were performed with nearly uniform fluvial gravel (D50=9 mm, D10=5 mm and D90=13 mm) to analyse the relationship between stream power and bed load transport rate in gravel-bed braided rivers at high grain Reynolds numbers. The values of the unit-width dimensionless bed-load rate qb* and unit-width dimensionless stream power ω* were evaluated in equilibrium conditions based on ten different experimental runs. Then, they were plotted along with values obtained during particularly representative field studies documented in the literature, and a regression law was derived. For comparison, a regression analysis was performed using the data obtained from laboratory experiments characterized by smaller grain sizes and, therefore, referring to relatively low grain Reynolds numbers. A numerical integration of Exner's equation was performed to reconstruct the local and time-dependent functional dependence of qb* and ω*. The results led to the following conclusions: 1) At equilibrium, the reach-averaged bed load transport rate is related to the reach-averaged stream power by different regression laws at high and low grain Reynolds numbers. Additionally, the transition from bed to suspended load transport is accelerated by low Re*, with the corresponding bed load discharge increasing with stream power at a lower, linear rate. 2) When tested against the gravel laboratory measurements, the high Re* power law derived in the present study performs considerably better than do previous formulas. 3) The longitudinal variability of the section-averaged equilibrium stream power is much more pronounced than that characterizing the bed load rate, at least for high Re*. Thus, the stream power and its local-scale heterogeneity seem to be directly responsible for transverse sediment re-distribution and, ultimately, for the determination of the spatial and temporal scales that characterize the gravel bedforms. 4) Finally, the stochastic interpretation of the wetted
Directory of Open Access Journals (Sweden)
Jochen eSchubert
2015-11-01
Full Text Available Metric resolution digital terrain models (DTMs of rivers now make it possible for multi-dimensional fluid mechanics models to be applied to characterize flow at fine scales that are relevant to studies of river morphology and ecological habitat, or microscales. These developments are important for managing rivers because of the potential to better understand system dynamics, anthropogenic impacts, and the consequences of proposed interventions. However, the data volumes and computational demands of microscale river modeling have largely constrained applications to small multiples of the channel width, or the mesoscale. This report presents computational methods to extend a microscale river model beyond the mesoscale to the macroscale, defined as large multiples of the channel width. A method of automated unstructured grid generation is presented that automatically clusters fine resolution cells in areas of curvature (e.g., channel banks, and places relatively coarse cells in areas lacking topographic variability. This overcomes the need to manually generate breaklines to constrain the grid, which is painstaking at the mesoscale and virtually impossible at the macroscale. The method is applied to a braided river with an extremely complex channel network configuration and shown to yield an efficient fine resolution model. The sensitivity of model output to grid design and resistance parameters is also examined as it relates to analysis of hydrology, hydraulic geometry and river habitats and the findings reiterate the importance of model calibration and validation.
Pereira, J. Michael; Roberts, Gary D.; Ruggeri, Charles R.; Gilat, Amos; Matrka, Thomas
2010-01-01
An experimental program is underway to measure the impact and high strain rate properties of triaxial braided composite materials and to quantify any degradation in properties as a result of thermal and hygroscopic aging typically encountered during service. Impact tests are being conducted on flat panels using a projectile designed to induce high rate deformation similar to that experienced in a jet engine fan case during a fan blade-out event. The tests are being conducted on as-fabricated panels and panels subjected to various numbers of aging cycles. High strain rate properties are being measured using a unique Hopkinson bar apparatus that has a larger diameter than conventional Hopkinson bars. This larger diameter is needed to measure representative material properties because of the large unit cell size of the materials examined in this work. In this paper the experimental techniques used for impact and high strain rate testing are described and some preliminary results are presented for both as-fabricated and aged composites.
Ioana-Toroimac, Gabriela
2016-07-01
The inventory of long-term braiding activity is a useful tool for detecting alterations in a rivers' hydromorphological state and for a river's management in the context of the Water Framework Directive on integrated river basin management for Europe. Our study focuses on braided sectors of rivers in South-Eastern Subcarpathians (Romania). The inventory evaluates types of alterations based on the spatial analysis of fluvial morphology indicators (i.e., length of the river sector forming a braided pattern; width of the braided active channel), and vegetation cover (i.e., length of banks covered by forest and shrubs; area of in-stream patches of shrubs) accumulated over the last century. Furthermore, we performed a regional scale hierarchical cluster analysis to estimate the degree of alteration when compared to an historical baseline. In South-Eastern Subcarpathians, the studied rivers experienced a decrease of braiding activity revealed by the shortening and narrowing of their braided sectors, expansion of riparian forests, and the diminishment of vegetated islands' areas. We separated three types of river clusters, corresponding to low (cluster 1), moderate (cluster 2), and high (cluster 3) degree of alteration. Moreover, the clusters demonstrate the evolutionary path of the braided pattern alterations until the functioning of another channel pattern. The inventory is relevant for differing types and levels of alterations. Additionally, this tool may serve as a first step toward the restoration of altered sectors by identifying rivers in cluster 1 as potential candidates of present-day reference sites for altered rivers with similar natural conditions as in cluster 3.
Gleason, C. J.; Smith, L. C.; Finnegan, D. C.; LeWinter, A. L.; Pitcher, L. H.; Chu, V. W.
2015-06-01
River systems in remote environments are often challenging to monitor and understand where traditional gauging apparatus are difficult to install or where safety concerns prohibit field measurements. In such cases, remote sensing, especially terrestrial time-lapse imaging platforms, offer a means to better understand these fluvial systems. One such environment is found at the proglacial Isortoq River in southwestern Greenland, a river with a constantly shifting floodplain and remote Arctic location that make gauging and in situ measurements all but impossible. In order to derive relevant hydraulic parameters for this river, two true color (RGB) cameras were installed in July 2011, and these cameras collected over 10 000 half hourly time-lapse images of the river by September of 2012. Existing approaches for extracting hydraulic parameters from RGB imagery require manual or supervised classification of images into water and non-water areas, a task that was impractical for the volume of data in this study. As such, automated image filters were developed that removed images with environmental obstacles (e.g., shadows, sun glint, snow) from the processing stream. Further image filtering was accomplished via a novel automated histogram similarity filtering process. This similarity filtering allowed successful (mean accuracy 79.6 %) supervised classification of filtered images from training data collected from just 10 % of those images. Effective width, a hydraulic parameter highly correlated with discharge in braided rivers, was extracted from these classified images, producing a hydrograph proxy for the Isortoq River between 2011 and 2012. This hydrograph proxy shows agreement with historic flooding observed in other parts of Greenland in July 2012 and offers promise that the imaging platform and processing methodology presented here will be useful for future monitoring studies of remote rivers.
Boerner, Audrey R.; Gates, John B.
2015-05-01
Impacts of environmental changes on groundwater carbon cycling are poorly understood despite their potentially high relevance to terrestrial carbon budgets. This study focuses on streambed groundwater chemistry during a period of drought-induced river drying and consequent disconnection between surface water and groundwater. Shallow groundwater underlying vegetated and bare portions of a braided streambed in the Platte River (Nebraska, USA) was monitored during drought conditions in summer 2012. Water temperature and dissolved inorganic carbon (dominated by HCO3-) in streambed groundwater were correlated over a 3 month period coinciding with a decline in river discharge from 35 to 0 m3 s-1. Physical, chemical, and isotopic parameters were monitored to investigate mechanisms affecting the HCO3- trend. Equilibrium thermodynamic modeling suggests that an increase of pCO2 near the water table, coupled with carbonate mineral weathering, can explain the trend. Stronger temporal trends in Ca2+ and Mg2+ compared to Cl- are consistent with carbonate mineral reequilibria rather than evaporative concentration as the primary mechanism of the increased HCO3-. Stable isotope trends are not apparent, providing further evidence of thermodynamic controls rather than evaporation from the water table. A combination of increased temperature and O2 in the dewatered portion of the streambed is the most likely driver of increased pCO2 near the water table. Results of this study highlight potential linkages between surface environmental changes and groundwater chemistry and underscore the need for high-resolution chemical monitoring of alluvial groundwater in order to identify environmental change impacts.
Hufenbach, W.; Gude, M.; Czulak, A.; Kretschmann, Martin
2014-04-01
Increasing economic, political and ecological pressure leads to steadily rising percentage of modern processing and manufacturing processes for fibre reinforced polymers in industrial batch production. Component weights beneath a level achievable by classic construction materials, which lead to a reduced energy and cost balance during product lifetime, justify the higher fabrication costs. However, complex quality control and failure prediction slow down the substitution by composite materials. High-resolution fibre-optic sensors (FOS), due their low diameter, high measuring point density and simple handling, show a high applicability potential for an automated sensor-integration in manufacturing processes, and therefore the online monitoring of composite products manufactured in industrial scale. Integrated sensors can be used to monitor manufacturing processes, part tests as well as the component structure during product life cycle, which simplifies allows quality control during production and the optimization of single manufacturing processes.[1;2] Furthermore, detailed failure analyses lead to a enhanced understanding of failure processes appearing in composite materials. This leads to a lower wastrel number and products of a higher value and longer product life cycle, whereby costs, material and energy are saved. This work shows an automation approach for FOS-integration in the braiding process. For that purpose a braiding wheel has been supplemented with an appliance for automatic sensor application, which has been used to manufacture preforms of high-pressure composite vessels with FOS-networks integrated between the fibre layers. All following manufacturing processes (vacuum infiltration, curing) and component tests (quasi-static pressure test, programmed delamination) were monitored with the help of the integrated sensor networks. Keywords: SHM, high-pressure composite vessel, braiding, automated sensor integration, pressure test, quality control, optic
Application of Excel VBA in Cable Braided Shielding Parameter Calculation%Excel VBA在电缆编织工艺参数计算中的应用
Institute of Scientific and Technical Information of China (English)
郭亚朋; 王海岭
2012-01-01
针对在电缆编织屏蔽参数计算中采用手动方法效率低、过程复杂的问题,采用Excel VBA对计算过程涉及的多项可变数据进行逐步确定,来实现参数计算的自动化。实际使用表明,在日常应用中Excel VBA可显著降低编织屏蔽计算的工作强度,并能提高工艺参数的合理性和数据的准确性。%Aiming at the problems of low efficiency and complex process in manually calculating cable braided shielding parameters,Excel VBA is used to determine various variable data involved during calculation step by step,so as to achieve automatic parameter calculation.The actual use shows that Excel VAB can significantly reduce the workload of calculating braided shielding,and improving the rationality of technological parameters and the data accuracy.
International Nuclear Information System (INIS)
The cranial cruciate ligament rupture is one of the main orthopaedic diseases which affect dogs. Many surgical techniques have been described and they aim to relief the pain, restore stifle biomechanical stability and prevent the progression of osteoarthritis. Fascia lata, braided polyester and polyamida were used in lateral fabellar suture to stifle stabilization after induced cranial cruciate ligament rupture in dogs that were submitted to radiographic and macroscopic evaluation of joint. In this study 18 dogs weighting more than 15kg were used (middleweight - 19.67kg), distributed in three groups corresponding to each technique, evaluated during 30 and 60 days. In the radiographic exam, the dogs had evidence of moderate to severe joint effusion, capsular distension and, in most cases, lacking of degenerative articular disease features. At the macroscopic exam of the stifle joint thickening of the joint capsule and periarticular soft tissues, erosion of the femoral condyles cartilage in all groups and loosening of the suture were observed in dogs submitted to extra-articular stabilization techniques employing braided polyester and polyamida
Cecotti, Sergio; Vafa, Cumrun
2011-01-01
We construct 3d, N=2 supersymmetric gauge theories by considering a one-parameter `R-flow' of 4d, N=2 theories, where the central charges vary while preserving their phase order. Each BPS state in 4d leads to a BPS particle in 3d, and thus each chamber of the 4d theory leads to a distinct 3d theory. Pairs of 4d chambers related by wall-crossing, R-flow to mirror pairs of 3d theories. In particular, the 2-3 wall-crossing for the A_2 Argyres-Douglas theory leads to 3d mirror symmetry for N_f=1 SQED and the XYZ model. Although our formalism applies to arbitrary N=2 models, we focus on the case where the parent 4d theory consists of pairs of M5-branes wrapping a Riemann surface, and develop a general framework for describing 3d N=2 theories engineered by wrapping pairs of M5-branes on three-manifolds. Each 4d chamber, which corresponds to a dual 3d description, maps to a particular tetrahedral decomposition of the UV 3d geometry. In the IR the physics is captured by a single recombined M5-brane which is a branche...
Lallias-Tacon, S.; Liébault, F.; Piégay, H.; Leduc, P.
2012-04-01
The recent development of innovative topographic survey technologies offers new opportunities for investigating spatial and temporal patterns of gravel-bed rivers morphological responses to flood events. In this study, multidate airborne LiDAR surveys were used to reconstruct reach-scale morphological changes of a gravel-bed braided river following a channel-forming flood event. LiDAR surveys were acquired in October 2008 and June 2010 for a 7-km reach of the Bès River, a very active aggrading braided channel, which is a tributary to the Bléone River in the Southern French Prealps (drainage area: 234 km2). Between these two dates, a 15-year flood occurred in December 2009, with a peakflow discharge of 171 m3 s-1. A DEM of difference (DoD) was produced by subtraction of LiDAR-derived DTM pair. Spatially distributed error in Dod was accounted with dGPS field measurement by sampling of different types of terrains (exposed gravel bars, spares and dense vegetated areas). The scour and fill maps allowed reconstructing erosion and deposition of bedforms and provide a volume estimate for calculating a sediment budget. These bedforms were described by different factors like their geometry (width, shape), their position and elevation relative to the main low-flow channel and their vegetation cover. Bed morphology was also studied by extracting different metrics at regularly-spaced cross-sections to infer information about sediment transfer in the braided channel. Final aim is to link bedform characteristics with their morphological response. Morphological changes were also studied in a historical context with a series of aerial photographs (1948-2010) to link the present-day morphology of the river with longer term channel changes. Active channel and island area were measured at reach and sub-reach scales (50 m), as well as active channel and island widths for cross-sections (every 10 m along). These variables were coupled with landscape changes and hydrological events in
Institute of Scientific and Technical Information of China (English)
王先德; 柳志伟; 杨发群; 刘一鸣
2012-01-01
It was introduced, about the Paleogeography sedimentary background of Bayanhua Group in Baiyinchagan Sag in the article. Based on a great quantity of geological data, sedimentary characteristics of braided river delta, such as lithology, architecture, sedimentary structure and sequence, were analyzed. Braided river delta is a kind of sedimentary type favorable for oil-gas enrichment in continental sedimentary basins. Braided channel in braid delta plain and underwater distributary channel in braid delta front can both form favorable reservoir, associated with cap rock vertically, creating favorable hydrocarbon reservoir conditions.%介绍了白音查干凹陷巴彦花群古地理沉积背景,依据大量的地质、钻井、录井及岩心资料,对都红木组及腾格尔组沉积的辫状河三角洲岩性、结构、沉积构造及其沉积序列等沉积特征展开详细分析.辫状河三角洲是沉积盆地中与油气富集有着紧密联系的沉积相型,期中三角洲平原辫状河道以及前缘水下分流河道构成相对较好的储层,在垂向上构成良好的储盖组合关系,创造了优势油气成藏条件.
Institute of Scientific and Technical Information of China (English)
JIANG Yiming; ZHANG Jinliang
2008-01-01
During the early Silurian, a transgressive and vast shallow sea with flat sea-floor covered the central Tarim Basin (the Tazhong area). The depositional environment of the middle member of the Kalpingtag Formation is controversial. In order to provide a basis for the prediction of reservoir sand, the sedimentary facies are recognized according to abundant core observations and de-scriptions combined with well-log analysis, isograms, seismic interpretations and regional sedimentary background. The middle member of the Kalpingtag Formation, which shows a retrograding sequence, is interpreted as braid-delta deposits influenced by mi-nor tidal reworking. The sources of clasts are from the southern uplift. The subaqueous braid-delta deposits in the study area have some characteristics quite different from the common deltas that generally deposit in marginal seas. Four facies grouped to a delta front association are recognized, ranging from distributary-channel (Facies A), front bar (Facies B), sand sheet (Facies C) and inter-distributary bay (Facies D). The distributary channels construct the sandbody framework of the delta front. Front bar deposits, which are fine-grained with low depositionai dips, display a near-continuous sand strip around the entire periphery of the delta. Sand sheet deposits are mainly found in front of Facies B, gradationally contacting with the prodelta. The interdistributary bay is essentially the uppermost unit capping the channel sequence and generally made up of laminated and massive mudstones. The delta front deposits display extensive sheet-like bodies contrasting with the characteristic wedge shapes of common subaqueous delta bodies. The bi-modal cross-stratification and mud drapes in the fine-to medium-grained sandstone in the distal area are inferred to reflect high-energy tidal processes.
Institute of Scientific and Technical Information of China (English)
王瑞; 肖长发; 刘美甜; 张旭良
2013-01-01
利用二维编织技术将聚丙烯腈(PAN)纤维编织成中空编织管,以聚丙烯腈为成膜聚合物,以聚乙二醇为成孔剂,配制铸膜液,采用同心圆纺丝法制备同质编织管增强型聚丙烯腈中空纤维膜.研究结果表明,所得同质编织管增强型聚丙烯腈中空纤维膜的表面分离层具有类似于非对称膜的结构,铸膜液可渗入编织管纤维束中；随着编织管编织节距的增大,同质编织管增强型聚丙烯腈中空纤维膜表面分离层厚度减小,同时膜的平均孔径增大,膜的纯水通量随之增大；铸膜液渗入编织管纤维束的现象未影响膜的通透性能；编织管的断裂强度最大可达100 MPa以上.通过水浴振荡、超声波水浴振荡及等力拉伸3种方法测试了同质编织管增强型中空纤维膜和异质编织管增强型中空纤维膜中编织管与表面分离层之间的界面结合性能,结果表明前者的界面结合性能优于后者.%Homogeneous braided tube reinforced polyacrylonitrile ( PAN) hollow fiber membranes which contained hollow braided tube and separation surface were prepared by concentric circles spinning method. The braided tube was prepared by the two-dimensional braided technique using PAN fibers. While the separation surface was obtained by non-solvent induced phase separation method with PAN as the polymer matrix, dimethyl sulfoxide (DMSO) as the solvent,and polyethylene glycol (PEG) as the pore-forming agent. Results showed that the structure of separation surface was similar to asymmetric membrane. The casting solution would penetrate into the voids among fiber bundles of the braided tube. As the braided pitch increasing, the thickness of separation surface decreased, which induced the promotion of the membrane water flux. There was no obvious influence of casting solution penetration on the membrane permeability. The breaking strength of braided tube was up to 100 MPa. Water bath vibration, ultrasonic vibration and
Institute of Scientific and Technical Information of China (English)
田长安; 王栓宏
2002-01-01
In 1997 Caenepeel, Militaru and Zhu[1] showed that there exist a Maschke type theorem for Doi-Hopf Modules. An analog result for braided Hopf modules was not known. In this paper, we introduce conception of braided Doi-Hopf module as the generalization of braided Hopf modules. They are Doi-Hopf modules over arbitrary Quasitriangular Hopf Algebras. We provide a Maschke type theorem for such braided Doi-Hopf modules.%1997年Caenepeel,Militaru和Zhu[1]证明了Doi-Hopf模的Maschke型定理,在这篇文章中,我们引进了辫子Doi-Hopf模,证明了类似的Maschke型定理.
Application of braided retraction cord in dentistry%编织排龈线在牙体修复中的应用
Institute of Scientific and Technical Information of China (English)
张衍军
2013-01-01
背景：排龈是标准牙体制备和精确印模制取的重要环节，对于患牙修复成功具有重要的意义。目的：评价编织排龈线在牙体修复中的应用效果。方法：对应用编织排龈线修复缺损牙体的患者进行随访观察，通过评估牙体修复的满意度以及龈缘出血、牙龈炎、牙周炎等相关并发症的发生情况评价排龈线在牙体修复中的作用，同时比较不同结构特征的排龈线在牙体修复中的效果。结果与结论：应用编织排龈线修复牙体缺损的367颗前牙和64颗后牙，降低了患牙修复后牙龈变色、龈缘出血、牙龈炎和牙周炎等牙周并发症的发生率。国产排龈线因内含明矾，具有良好的止血功能，能够获得满意的修复效果，而进口排龈线因网状编织结构同样具有较好的止血功能以及获得满意的修复效果，二者在牙体修复过程中的满意率无明显差异。% BACKGROUND: Gingival is the important part in the preparation of standard dental body and accurate impression, which has great significance in the repairing of diseased teeth. OBJECTIVE: To evaluate the application effect of braided retraction cord in dentistry. METHODS: The patients who received braided retraction cord for repairing of dental defects were fol owed-up, and the effect of retraction cord on dentistry through assessing the satisfaction of dentistry and the related complications of gingival bleeding, gingivitis and periodontitis. The effect of retraction cord with different structural characteristics in dentistry was compared. RESULTS AND CONCLUSION: The braided retraction cord for the repairing of 367 anterior and 64 posterior dental defects could reduce the incidence of periodontal complications of gum discoloration, gingival bleeding, gingivitis and periodontitis. Domestic retraction cord as it contains alum has a good hemostatic function and can obtain satisfactory restoration effect. The
Institute of Scientific and Technical Information of China (English)
严实; 李冬华; 泮世东; 冯吉才
2013-01-01
基于声发射(AE)技术研究了不同编织角度的三维四向炭/环氧编织复合材料在压缩载荷作用下的破坏过程.分析了累积声发射能量,事件率,幅值和波形经过快速傅里叶变换后的峰值频率.同时,结合载荷-位移曲线,把破坏过程分成不同的阶段来深入理解编织复合材料的破坏机理.用光学显微镜观测试件的破坏表面.结果表明AE参数能很好地描述三维编织复合材料的破坏过程,而且破坏机理也可用AE特性来识别.%The fracture process of 3D four-directional carbon/epoxy braided composites with different braiding angles under the monotonic compressive loading were investigated by the acoustic emission (AE) technique. The cumulative AE energy, event rate, amplitude, and the peak frequency of a dominant frequency band after treated with the fast Fourier transform (FFT) were analyzed. At the same time, combining with the load-displacement curve varying feature, the fracture processes were divided into different stages to deeply understand the damaged mechanisms of the textile composites. Furthermore, the fracture surfaces of the specimens were observed under optical microscopy. Results reveal that the behavior of AE parameters described well the fracture process in the 3D braided composites with different braiding angles, and the damage mechanisms of the composites can be successfully identified by AE characteristics.
Robinson, J.W.; McCabea, P.J.
1997-01-01
Excellent three-dimensional exposures of the Upper Jurassic Salt Wash Sandstone Member of the Morrison Formation in the Henry Mountains area of southern Utah allow measurement of the thickness and width of fluvial sandstone and shale bodies from extensive photomosaics. The Salt Wash Sandstone Member is composed of fluvial channel fill, abandoned channel fill, and overbank/flood-plain strata that were deposited on a broad alluvial plain of low-sinuosity, sandy, braided streams flowing northeast. A hierarchy of sandstone and shale bodies in the Salt Wash Sandstone Member includes, in ascending order, trough cross-bedding, fining-upward units/mudstone intraclast conglomerates, singlestory sandstone bodies/basal conglomerate, abandoned channel fill, multistory sandstone bodies, and overbank/flood-plain heterolithic strata. Trough cross-beds have an average width:thickness ratio (W:T) of 8.5:1 in the lower interval of the Salt Wash Sandstone Member and 10.4:1 in the upper interval. Fining-upward units are 0.5-3.0 m thick and 3-11 m wide. Single-story sandstone bodies in the upper interval are wider and thicker than their counterparts in the lower interval, based on average W:T, linear regression analysis, and cumulative relative frequency graphs. Multistory sandstone bodies are composed of two to eight stories, range up to 30 m thick and over 1500 m wide (W:T > 50:1), and are also larger in the upper interval. Heterolithic units between sandstone bodies include abandoned channel fill (W:T = 33:1) and overbank/flood-plain deposits (W:T = 70:1). Understanding W:T ratios from the component parts of an ancient, sandy, braided stream deposit can be applied in several ways to similar strata in other basins; for example, to (1) determine the width of a unit when only the thickness is known, (2) create correlation guidelines and maximum correlation lengths, (3) aid in interpreting the controls on fluvial architecture, and (4) place additional constraints on input variables to
Vázquez Tarrío, Daniel; Borgniet, Laurent; Recking, Alain; Liebault, Frédéric; Vivier, Marie
2016-04-01
The present research is focused on the Vénéon river at Plan du Lac (Massif des Ecrins, France), an alpine braided gravel bed stream with a glacio-nival hydrological regime. It drains a catchment area of 316 km2. The present research is focused in a 2.5 km braided reach placed immediately upstream of a small hydropower dam. An airbone LIDAR survey was accomplished in October, 2014 by EDF (the company managing the small hydropower dam), and data coming from this LIDAR survey were available for the present research. Point density of the LIDAR-derived 3D-point cloud was between 20-50 points/m2, with a vertical precision of 2-3 cm over flat surfaces. Moreover, between April and Juin, 2015, we carried out a photogrammetrical campaign based in aerial images taken with an UAV-drone. The UAV-derived point-cloud has a point density of 200-300 points/m2, and a vertical precision over flat control surfaces comparable to that of the LIDAR point cloud (2-3 cm). Simultaneously to the UAV campaign, we took several Wolman samples with the aim of characterizing the grain size distribution of bed sediment. Wolman samples were taken following a geomorphological criterion (unit bars, head/tail of compound bars). Furthermore, some of the Wolman samples were repeated with the aim of defining the uncertainty of our sampling protocol. LIDAR and UAV-derived point clouds were treated in order to check whether both point-clouds were correctly co-aligned. After that, we estimated bed roughness using the detrended standard deviation of heights, in a 40-cm window. For all this data treatment we used CloudCompare. Then, we measured the distribution of roughness in the same geomorphological units where we took the Wolman samples, and we compared with the grain size distributions measured in the field: differences between UAV-point cloud roughness distributions and measured-grain size distribution (~1-2 cm) are in the same order of magnitude of the differences found between the repeated Wolman
Frost, M.; Sedlák, P.; Kruisová, A.; Landa, M.
2014-07-01
Self-expanding stents or stentgrafts made from Nitinol superelastic alloy are widely used for a less invasive treatment of disease-induced localized flow constriction in the cardiovascular system. The therapy is based on insertion of a stent into a blood vessel to maintain the inner diameter of the vessel; it provides highly effective results at minimal cost and with reduced hospital stays. However, since stent is an external mechanical healing tool implemented into human body for quite a long time, information on the mechanical performance of it is of fundamental importance with respect to patient's safety and comfort. Advantageously, computational structural analysis can provide valuable information on the response of the product in an environment where in vivo experimentation is extremely expensive or impossible. With this motivation, a numerical model of a particular braided self-expanding stent was developed. As a reasonable approximation substantially reducing computational demands, the stent was considered to be composed of a set of helical springs with specific constrains reflecting geometry of the structure. An advanced constitutive model for NiTi-based shape memory alloys including R-phase transition was employed in analysis. Comparison to measurements shows a very good match between the numerical solution and experimental results. Relation between diameter of the stent and uniform radial pressure on its surface is estimated. Information about internal phase and stress state of the material during compression loading provided by the model is used to estimate fatigue properties of the stent during cyclic loading.
Brasington, J.; Hicks, M.; Wheaton, J. M.; Williams, R. D.; Vericat, D.
2013-12-01
Repeat surveys of channel morphology provide a means to quantify fluvial sediment storage and enable inferences about changes in long-term sediment supply, watershed delivery and bed level adjustment; information vital to support effective river and land management. Over shorter time-scales, direct differencing of fluvial terrain models may also offer a route to predict reach-averaged sediment transport rates and quantify the patterns of channel morphodynamics and the processes that force them. Recent and rapid advances in geomatics have facilitated these goals by enabling the acquisition of topographic data at spatial resolutions and precisions suitable for characterising river morphology at the scale of individual grains over multi-kilometre reaches. Despite improvements in topographic surveying, inverting the terms of the sediment budget to derive estimates of sediment transport and link these to morphodynamic processes is, nonetheless, often confounded by limited knowledge of either the sediment supply or efflux across a boundary of the control volume, or unobserved cut-and-fill taking place between surveys. This latter problem is particularly poorly constrained, as field logistics frequently preclude surveys at a temporal frequency sufficient to capture changes in sediment storage associated with each competent event, let alone changes during individual floods. In this paper, we attempt to quantify the principal sources of uncertainty in morphologically-derived bedload transport rates for the large, labile, gravel-bed braided Rees River which drains the Southern Alps of NZ. During the austral summer of 2009-10, a unique timeseries of 10 high quality DEMs was derived for a 3 x 0.7 km reach of the Rees, using a combination of mobile terrestrial laser scanning, aDcp soundings and aerial image analysis. Complementary measurements of the forcing flood discharges and estimates of event-based particle step lengths were also acquired during the field campaign
Institute of Scientific and Technical Information of China (English)
胡雯; 黄争鸣
2009-01-01
PU nanofibers were fabricated by means of electrospinning and were collected undirectionally using a rotating disk. The relationship between a rotating speed and fiber alignment was studied. The collected fiber bundles were post processing treated using the techniques such as heating, stretching, twisting, and preforming, before they were made into a braided wire. Optimal post processing parameters were obtained in order to achieve the highest mechanical properties for the fiber bundles. It was shown that the braided wires had a much better mechanical performance than that of the unidirectionally collected fiber bundles before the post treatments, and even better than that after the treatments. This high mechanical behavior implies that the braided wires based on aligned electrospun nanofibers will have potential applications in textile and biomedical fields.%采用静电纺丝法制备出了纳米级、亚微米级纤维,采用尖角圆盘收集成具有定向排列的单向纤维束,考察了圆盘转速对纤维定向性的影响.为提高纤维的强度和模量,对收集到的纤维束进行了热处理、拉伸、加捻、定型等后处理工艺,再将多股定型的纤维束编织成线.研究了上述工艺参数对纤维束力学性能的影响,选取最佳工艺参数编织纤维束,并研究了编织线的力学性能.良好的性能预示其在纺织、生物医学等领域具有潜在的应用前景.
Institute of Scientific and Technical Information of China (English)
郑春红; 周光明; 董伟峰; 王宇; 曹然
2014-01-01
对四步法三维五向编织工字梁结构的弯曲性能进行了数值分析和实验研究。首先根据三维五向编织复合材料细观结构模型对材料进行刚度预测，讨论编织参数对材料性能的影响；在此基础上，将预测得到的单胞力学性能应用到宏观结构上，建立三维五向工字梁有限元模型，对其弯曲性能进行数值分析；最后采用RTM工艺制作工字梁试件进行四点弯曲试验，将结果与有限元计算结果进行对比。结果显示，编织参数的变化对三维五向编织复合材料的性能有着较大影响，有限元分析结果与试验结果基本一致。%Experimental study and numerical analysis were made on the bending properties of three-dimensional five-directional braided I-shaped composite structure. Firstly,a microstructure model was built to predict the rigidity of the material and study the effects of braiding parameters on the material properties. Based on these,the predicted mechanical properties of the unit cell were used in macrostructure to build a finite element model for the three-di-mensional five-directional I-shaped composite structure and make numerical analysis on its bending properties. Fi-nally,I-shaped composite specimens were molded by RTM to make four-point bending tests and compare the test re-sults with the finite element calculation results. This study showed:( 1 ) The change of braiding parameters had a strong influence on the properties of the braided composite structure;(2) The results of finite element analysis vir-tually agreed with the experimental results.
Institute of Scientific and Technical Information of China (English)
万莉; 马永军; 李静东
2015-01-01
结合三维编织复合材料制造工艺，提出了利用碳纳米线传感器对三维编织复合材料试件缺陷检测的应用方法。论述了碳纳米线传感器嵌入三维编织复合材料预制件的方式，分析了碳纳米线传感器的力学特性。分析了编织角对嵌入碳纳米线传感器的影响。系统使用传统的应变放大器测量电阻变化。最后，应用响应面法对实验结果进行统计分析。实验表明，本实验的研究方法成功地实现了三维编织复合材料内部缺陷位置和大小的估计。%According to braiding process of three-dimensional braided composites, the paper proposes nonde-structive testing method for three-dimensional braided composites based on carbon nanotube thread sensor. Dis-cussed the way of the carbon-nano thread sensors embedded in three-dimensional braided composite preform. Ana-lyzed the mechanical properties of carbon nanotube thread sensors. We analyzed the braiding angle influence on carbon nanotube thread sensor embedded into preform. The electric resistance changes were measured using con-ventional strain gage amplifier. Finally,the experimental results were analyzed using response surface method. As a result,the present method successfully provides estimations of location and size of internal defects for three-dimen-sional braided composites.
Institute of Scientific and Technical Information of China (English)
周爱忠; 张禹; 郁岳峰; 张勋
2013-01-01
聚乙烯编织网线比普通聚乙烯捻线强度高,用编织线来替代目前的普通捻线,可降低拖网渔具的阻力从而达到节能降耗的目的.本文通过实际取样测试,比较了两种网线的拉伸性能,在不降低原拖网渔具的单线结强力的前提下,用聚乙烯编织线代替原普通捻线,并通过模型试验研究其对拖网渔具性能的影响和节能效果.结果表明:单线结强力相同的两种网线,编织线的直径可比普通网线的直径下降15.17％以上.本试验编织线拖网的平均网线直径比原普通捻线拖网下降16.00％,网具阻力面积(线面积)从304.57 m2下降到256.47 m2,下降了15.79％.同等试验条件下,编织线拖网的阻力比普通捻线拖网下降17.25％左右,而网口高度的变化则不明显.能耗系数的计算结果为编织线拖网过滤同体积的水体所消耗的能量比普通捻线拖网下降16.67％.功率消耗的分析表明,消耗同样的功率,440 kW的双拖渔船使用编织线拖网,拖速可比普通捻线拖网提高8.33％,如采用和普通捻线拖网同样的拖速作业,则去掉起、放网所消耗的时间,以一天正常拖网作业18 h计算,可节约燃油77 L左右.%Polyethylene is the most widely used net material in fishing trawls, and the strength of braided polyethylene netting twine is better than common polyethylene twisting. Using braided polyethylene netting twine to replace the current common polyethylene twisting can reduce the resistance of the trawl fishing gear, achieving the purpose of energy saving. This study compared the tensile mechanical properties of the two netting twines, and used braided polyethylene netting twine to replace the current common polyethylene twisting without reducing the knot strength, and trawl fishing gear performance and energy-saving effects were tested in flume tank. The results showed that: with the same knot strength, the diameter of braided polyethylene netting twine decreased
Institute of Scientific and Technical Information of China (English)
马小菲; 张国利; 朱有欣; 陈光伟
2014-01-01
Quasi-static axial compression and three point bending tests are performed to study the compression and flexural performance of glass/kevlar hybrid composite pipe. The effect of braiding angle and fiber hybrid ratio on the compression and flexural performance of composite pipe are investigated and the fracture features are also analyzed. It is found that when the braiding angle is 30°, 45°and 60°respectively, the compression strength of composite pipe with glass/kevlar hybrid ratio 1∶1 is the lowest. The compression strength of 2G/2K-60 is 58.4 MPa, it decreases about 31.7%compared with pure glass fiber pipe G-60. In addition, with the same braiding angle, the bending strength of the tube is the highest with glass/kevlar hybrid ratio 1∶3. The tube G/3K-30 has the best bending performance. When glass/kevlar hybrid ratio is 3∶1, 1∶1 and 1∶3 respectively, the smaller braiding angle is, the bigger compression strength and bending strength will be. It is found that the fiber hybrid ratio and braiding parameters have an important influence on the compression and flexural failure mechanism of composite pipe.%通过玻璃/芳纶混杂纤维复合材料圆管的轴向静态压缩和三点弯曲实验，分析了复合材料圆管的压缩及弯曲性能，探讨了编织角和纤维混杂比对复合材料圆管压缩及弯曲性能的影响，并对其破坏形式进行了分析.结果表明：当编织角分别为30°、45°和60°时，玻璃/芳纶混杂比为1∶1时圆管的压缩强度最低，圆管2G/2K-60的压缩强度最低为58.4 MPa，比纯玻璃纤维圆管G-60降低了约31.7%；另外，在相同编织角下，玻璃/芳纶混杂比为1∶3时圆管的弯曲强度最高，复合材料圆管G/3K-30具有最好的弯曲性能；当玻璃/芳纶混杂比分别为3∶1、1∶1和1∶3时，编织角越小，圆管的压缩强度和弯曲强度越大.可见，复合材料圆管的压缩和弯曲破坏机理与纤维混杂比及编织工艺参数有关.
Braiding knots with topological strings
International Nuclear Information System (INIS)
For an arbitrary knot in a three-sphere, the Ooguri-Vafa conjecture associates to it a unique stack of branes in type A topological string on the resolved conifold, and relates the colored HOMFLY invariants of the knot to the free energies on the branes. For torus knots, we use a modified version of the topological recursion developed by Eynard and Orantin to compute the free energies on the branes from the Aganagic-Vafa spectral curves of the branes, and find they are consistent with the known colored HOMFLY knot invariants a la the Ooguri-Vafa conjecture. In addition our modified topological recursion can reproduce the correct closed string free energies, which encode the information of the background geometry. We conjecture the modified topological recursion is applicable for branes associated to hyperbolic knots as well, encouraged by the observation that the modified topological recursion yields the correct planar closed string free energy from the Aganagic-Vafa spectral curves of hyperbolic knots. This has implications for the knot theory concerning distinguishing mutant knots with colored HOMFLY invariants. Furthermore, for hyperbolic knots, we present methods to compute colored HOMFLY invariants in nonsymmetric representations of U(N). The key step in this computation is computing quantum 6j-symbols in the quantum group Uq(slN).
Braiding knots with topological strings
Energy Technology Data Exchange (ETDEWEB)
Gu, Jie
2015-08-15
For an arbitrary knot in a three-sphere, the Ooguri-Vafa conjecture associates to it a unique stack of branes in type A topological string on the resolved conifold, and relates the colored HOMFLY invariants of the knot to the free energies on the branes. For torus knots, we use a modified version of the topological recursion developed by Eynard and Orantin to compute the free energies on the branes from the Aganagic-Vafa spectral curves of the branes, and find they are consistent with the known colored HOMFLY knot invariants a la the Ooguri-Vafa conjecture. In addition our modified topological recursion can reproduce the correct closed string free energies, which encode the information of the background geometry. We conjecture the modified topological recursion is applicable for branes associated to hyperbolic knots as well, encouraged by the observation that the modified topological recursion yields the correct planar closed string free energy from the Aganagic-Vafa spectral curves of hyperbolic knots. This has implications for the knot theory concerning distinguishing mutant knots with colored HOMFLY invariants. Furthermore, for hyperbolic knots, we present methods to compute colored HOMFLY invariants in nonsymmetric representations of U(N). The key step in this computation is computing quantum 6j-symbols in the quantum group U{sub q}(sl{sub N}).
Research on Axial Performances of 3D Braided Composite Circular Tubes%三维编织复合材料圆管轴向力学性能试验研究
Institute of Scientific and Technical Information of China (English)
黄雨霓; 刘振国
2014-01-01
本文针对三维四向、五向编织T700/环氧树脂复合材料，采用四步法编织工艺，编织圆管预成型件，利用VARTM工艺固化成型，并进行拉伸和压缩试验，得到两类材料圆管的轴向性能数据。试验结果表明院三维四向和五向复合材料圆管轴向性能在破坏前基本保持线弹性，四向材料拉伸和压缩模量相近，五向材料压缩模量大于拉伸模量，两者拉伸强度均远大于压缩强度，且五向材料破坏具有脆性特征。此外，三维四向编织复合材料的轴向力学性能低于三维五向编织复合材料。%Tube performs for the 3D 4-directional and 3D 5-directional materials were produced by four step braiding method and T-700/epoxy composites were made by VARTM. A study of tensile and compression properties for the two materials were carried out. The results indicate that the axial performances maintain linear elasticity before failure and the tensile strength is much larger than the compressive strength for the two materials. The tensile elastic modulus of the 3D 4-directional material is similar to the compressive elastic modulus. The compressive elastic modulus is larger than the tensile strength for the 3D 5-directional material and the failure?form is characterized by brittle cracks. Moreover, the axial properties of 3D 4-directional braided composites are lower than that of 3D 5-directional braided composites.
Comiti, F.; da Canal, M.; Surian, N.; Mao, L.; Lenzi, M. A.
2007-05-01
This study aims to determine the timing and the extent of the morphological changes occurred in a 30-km long reach of a gravel bed river of the Eastern Italian Alps (the Piave river, in the Val Belluna synclinal), now covered with abundant riparian vegetation and forested islands that may represent important source of wood during floods. The Piave river (drainage area 3,300 km2 at the exit of the montane district) was once characterised by a wide, braided active channel confined by climatic terraces formed during the last glacial retreat (Holocene). It underwent a strong narrowing during the last century that led to a wandering/single-thread morphology, leaving large areas available to the establishment of riparian forests (genus Populus, Salix, Robinia). It is notable that some of these woodlands are now most valuable under an ecological perspective, in particular they represent important nesting sites for avifauna (EC BIRDS Directive). Nine sets of historical maps and aerial photos (from 1805 to 2003) were used to determine changes in the Piave river corridor (active channel width, vegetation cover, island areas and number), georeferencing and editing maps by a GIS software. Two series of cross-sections (1935-2003) allowed to get insights into the vertical evolution of the streambed. Discharge data (from 1926) permitted to assess the possible effect of flow regulation on formative discharge. Results indicate that average channel width (i.e. channel area/channel length) dropped from about 600 m during the XIX century to 200 m in the 1991, and increased thereafter up to 300 m in the 2003. The dynamics of riparian vegetation follows a clear complementary trend. Such a pattern reflects the different human impacts on the river system, particularly the gravel mining activity intensely carried out in the '70-'80. Large forested islands were already present at the early XIX century, but their extension relative to channel area was much smaller (3 times) than in 1991
Institute of Scientific and Technical Information of China (English)
李蕾
2013-01-01
3D braided polyethylene,ultra-high molecular weight(PE-UHMW) fiber reinforced epoxy(EP) resin composites were prepared using resin transfer molding process.The effects of load and fiber volume content on friction and wear characteristics of the composites were investigated on a friction and wear tester,and the microscopic wear surface was analyzed using scanning electron microscopy.The results show that the friction coefficient and wear rate decrease with fiber volume content increasing;and with the increase of load,the friction coefficient of composites decreases,however,the wear rate of composites increases.The wear mechanisms of the EP/3D braided PE-UHMW fiber composites are mainly adhesive wear.%以三维编织超高分子量聚乙烯(PE-UHMW)纤维为增强体，环氧树脂(EP)为基体，通过树脂传递模塑工艺制备了EP/三维编织PE-UHMW纤维复合材料，研究了纤维含量和载荷对复合材料摩擦系数与磨损率的影响，并采用扫描电子显微镜对复合材料磨损表面进行了分析。结果表明，随着纤维体积含量的增加，复合材料的摩擦系数和磨损率逐渐减小；随着载荷的增大，复合材料的摩擦系数逐渐减小，但磨损率增大；复合材料的磨损机制以粘着磨损为主。
Institute of Scientific and Technical Information of China (English)
焦亚男; 李嘉禄
2008-01-01
This research dealt with the impact and Compression-After-Impact properties of epoxy matrix composite beams manufactured from three-dimensional braided glass fabrics.Three different architectures of the braid structures,4-Direction,5-Direction and 6-Direction,were investigated together with three further various braiding angles of each architecture.The effect of architecture and braiding angle parameters upon the impact and CAI properties was examined.Damage morphology and failure mechanisms of the impacted materials were characterized.It has been found that the parameters affected the damage resistance and tolerance of composites evidently.6-Directional composites showed high impact toughness,whereas 5-Directional ones had higher CAI strength compared with others which had same braiding angle.Failure of the specimens with small damage area revealed the brittle characteristic of 3D braided composite.%试验制备了三维编织四向结构、五向结构和六向结构的玻璃纤维预制件增强环氧树脂梁的复合材料试样,每种试样包含20°、30°和40°三个编织角度.研究了编织结构和编织角参数对复合材料低速冲击及冲击后压缩性能的影响,分析了损伤后的试样形貌及破坏情况.试验结果表明:编织参数对复合材料的损伤容限影响较显著;编织角相同时,五向结构具有较高的CAI强度,而六向结构则表现出较好的冲击韧性;编织结构相同时,30°编织角试样的抗冲击性能较好;同时,冲击后压缩试样表现出脆性断裂特征.
Morscher, Gregory N.; Yun, Hee Mann; DiCarlo, James A.
2007-01-01
The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for architectural design of CMC components that are subjected to multi-axial stress states. In this study, 2D-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0 degree and 90 degree directions were tensile loaded in-plane in the 0 degree direction and at 45 degree to this direction. In addition, a 2D triaxially-braided MI composite panel with balanced fiber content in the plus or minus 67 degree bias directions and reduced fiber content in the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23 degrees from the bias fibers). Stress-strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0 degree direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on critical matrix flaws for a given composite stress. Also for the 0/90 panel loaded in the 45 degree direction, an improved distribution of matrix flaws existed due to the absence of fiber tows perpendicular to the loading direction. In addition, for the +67/0/-67 braided panel, the axial tows perpendicular to the loading direction were not only low in volume fraction, but were also were well separated from one another. Both off-axis oriented panels also showed relatively good ultimate tensile strength when compared to other off-axis oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial
Properties of 2.5D Braided Carbon/Phenolic Compression Composites%2．5D碳／酚醛模压复合材料的性能研究
Institute of Scientific and Technical Information of China (English)
杨斌; 闫红英; 杨晓军
2013-01-01
采用真空浸胶技术和模压成型工艺研制2．5D编织碳纤维/酚醛新型树脂基防热复合材料，对材料的拉伸性能、烧蚀性能和热常数等进行了测试。结果表明：2．5D碳/酚醛模压复合材料拉伸强度为424 MPa、拉伸模量为66．4 GPa，氧-乙炔线烧蚀率为0．013 mm/s，质量烧蚀率为0．049 g/s，比热容大于1．1 J/（g· K），导热系数小于0．6 W/（m · K），与传统的短纤维、碳布增强的酚醛模压材料相比，2．5D碳/酚醛模压复合材料具有较好的综合性能，可作为结构防热一体化复合材料。%2.5D braided carbon/phenolic composite as new resin matrix thermal protection material was investigated by vacuum impregnation and compression molding .Tensile properties ,ablative properties and thermal constants of the compos-ite were studied.Results indicated the tensile and tensile modulus were 424 MPa,66.4 GPa.The linear ablation rate and mass ablation rate of oxyacetylene were 0.013 mm/s and 0.049 g/s.The thermal conductivity didn’t exceed 0.6 W/(m· K).The specific heat exceed 1.1 J/(g· K).The combined performance of 2.5D braided carbon/phenolic compression composite was better than that of chopped fiber phenolic composite or carbon cloth phenolic .It can bused as thermal protec-tion and structural material .
Institute of Scientific and Technical Information of China (English)
袁新涛; 吴向红; 张新征; 晋剑利
2013-01-01
According to the characteristics of complicated reservoir architecture of braided river and based on the basic principle of sedimentology and high resolution sequence stratigraphy, sedimentary origin of interlayer and interbed were analyzed and a method was proposed for predicting impermeable layer between wells. The results show that abandoned channel, inter-bar mud, fall silt and overbank are main origin types in barrier and interbed construct. Preservation of muddy deposition is closely related to accommodation space and sedimentary alimentation. Based on analysis of deposit genesis, shapes of different interbed types of mud were described according to single well log interpretation and well correlation. And sedimentary model of barrier and interbed was developed. Furthermore, the sedimentary model can be used in constructing training image after optimal selection. Prediction of barrier and interbed achieved by multi-point statisetics can effectively reflect the geometric morphology and distribution of interbed, which is more consistent with the sedimentary model of the braided river.%针对辫状河储层内隔夹层的复杂结构特征,依据沉积学及高分辨率层序地层学基本原理,对Fula油田辫状河储层内隔夹层的沉积成因及井间预测方法进行研究.结果表明:废弃河道、坝间泥、心滩落淤层、越岸沉积是构成辫状河夹层的主要沉积类型,泥质沉积物的保存与可容纳空间、沉积物供给速度有着密切联系；在沉积成因分析基础上,可根据单井测井解释和连井对比来描述各类夹层的空间形态,建立夹层的沉积模式；在辫状河相储层中,应用多点地质统计学方法预测井间泥质夹层分布,可以更有效地体现夹层的几何形态和分布规律,其更加符合辫状河夹层的沉积模式.
Institute of Scientific and Technical Information of China (English)
何用; 张金明; 何贞俊
2015-01-01
珠江三角洲河网区河道受径流、潮汐动力双重作用,汊道分流随径流潮汐动力变化而变化,险段形成机理较单一河道复杂,传统治理方案易改变汊口两侧河道的分流比,影响整治效果. 在分析了典型分汊险段附近河床演变特征的基础上,分析险段水动力特性,研究了其形成机理,并对各种整治防护措施进行对比试验.结果表明,模袋混凝土方案不改变汊道分流,不增加相邻河道泄流压力,且其整体性、适应性和高抗冲性避免了险段所在岸坡及河床的冲刷,可起到防护岸坡与堤脚的作用. 该整治方案可为相关分汊河道险段治理提供借鉴.%The river channel in the Pearl River Delta is influenced by the dynamics of runoff and tide, the diversion ratio of the braided river changes with the joint dynamics of runoff and tide, so the formation mechanism of pitch is more complex than that in a single channel. The effect of traditional control scheme would be affected because the river diversion ratio at branch mouth changes easily. Based on the analysis of the riverbed evolution characteristics of typical braided pitch, the hydrodynamic charac-teristics are discussed, and the pitch formation mechanism is revealed. The various regulation protection measures are studied by physical model experiments. The result shows that the mold bag concrete scheme doesn't change the diversion ratio nor increase the discharge pressure on adjacent channel. The pitch in the bank and riverbed can be protected from scouring by the integrity, adaptability and high impact resistance of the scheme, which can protect the bank and levee toe.
Institute of Scientific and Technical Information of China (English)
周畅; 殷虎; 杨华荣; 刘刚; 许荣彧; 瞿丹; 樊友文
2015-01-01
Aimed at the influence of the grounding resistance on the shielding effectiveness of the cable shield,the influence of the grounding resistance on the shielding effectiveness of the braided shield is studied in this paper. Based on the application of CST cable studio and engineering practice, the 3D simulation models of launching and receiving cables are established and the system with different grounding resistance are established and the influence of the grounding resistance on the shielding effectiveness of the braided shield are analyzed, respectively. The results show that, when the value of the grounding resistance is small, shielding effectiveness of the braided shield remains constant at the frequency of the maximum value of the coupling voltage with the rising of the grounding resistance and the shielding effectiveness of the braided shield becomes a little worse at other frequency, and, when the value of the grounding resistance is larger, the shielding effectiveness of the braided shield becomes worse quickly with the rising of the grounding resistance among the whole frequency.%文章针对舰船工程中接地电阻对于电缆屏蔽层屏蔽效果影响的问题，重点讨论了接地电阻对于金属编织网屏蔽层屏蔽效果的影响。基于CST电磁场仿真设计平台，结合工程实际，建立发射及接收电缆三维仿真模型，对不同接地电阻对金属编织网屏蔽层屏蔽效果的影响进行仿真和分析，研究结果表明，对于一定长度的电缆，当接地电阻低于一定值时，随着接地电阻的增加，感应电压最高值对应的频点处，金属编织网屏蔽效果变化不大，其余频点的屏蔽效果略微降低；当接地电阻高于一定值时，随着接地电阻的增加，整个频段内，金属编织网屏蔽效果迅速降低。
Braided Composite Technologies for Rotorcraft Structures Project
National Aeronautics and Space Administration — The Phase 2 effort will be used to advance the material and design technologies that were explored in the Phase 1 study of hybrid gears. In this hybrid approach,...
Braided Composite Technologies for Rotorcraft Structures Project
National Aeronautics and Space Administration — The proposed program will focus on the development of a new generation of advanced technology for rotorcraft transmission systems. This program will evaluate the...
Topological vacuum bubbles by anyon braiding
Han, Cheolhee; Park, Jinhong; Gefen, Yuval; Sim, H.-S.
2016-01-01
According to a basic rule of fermionic and bosonic many-body physics, known as the linked cluster theorem, physical observables are not affected by vacuum bubbles, which represent virtual particles created from vacuum and self-annihilating without interacting with real particles. Here we show that this conventional knowledge must be revised for anyons, quasiparticles that obey fractional exchange statistics intermediate between fermions and bosons. We find that a certain class of vacuum bubbl...
Institute of Scientific and Technical Information of China (English)
张兆民; 付业伟; 张翔; 朱文婷; 宁满霞
2013-01-01
采用湿法工艺制备3种不同编织密度的碳布增强树脂基摩擦材料。利用湿式惯量摩擦试验机研究碳布编织密度对材料摩擦磨损性能的影响。同时利用扫描电子显微镜观察磨损后材料的表面微观形貌。结果表明：随着碳布编织密度的增大，摩擦制动时间延长，摩擦力矩值变小，摩擦制动过程更加平稳；动摩擦因数和静摩擦因数减小，磨损率增大。动摩擦因数随着制动压力和转速的增加而减小，静摩擦因数随着制动压力的增大而减小。编织密度较大的试样，磨损后表面发生较为严重的纤维断裂、拔出及树脂脱黏现象。制备的碳布增强树脂基摩擦材料比纸基摩擦材料具有更加优异的耐热性能。%Three kinds of carbon fabric/ phenolic composites were prepared using the wet impregnation process,with different braiding count carbon fabric as reinforcement respectively. The tribological properties of the carbon fabric compos-ites were investigated on an inertia wet friction tester and the worn surface morphology was analyzed by scanning electron microscope. The results show that with the braiding count of carbon fabric increasing,the braking time is prolonged and the friction torque is decreased,while the braking process become more stable;the dynamic friction coefficient and the static friction coefficient are decreased while the wear rate is increased. The dynamic friction coefficient is decreased along with the increasing of braking pressure and rotating speed,the static friction coefficient decreased along with the increasing of braking pressure. The breakage and removal of carbon fibers along with resin peeling off from the surface are obviously found on the sample with higher braiding count. The carbon fabric/ phenolic friction material processed has better heat re-sistance than the paper - based friction material.
Institute of Scientific and Technical Information of China (English)
王玉果
2009-01-01
Three-dimensionally(_3D)braided carbon fiber reinforced epoxy resin(C_3D/EP)composites have been prepared by resin transfer molding(RTM)process. The moisture absorption characteristics,influence of temperature on the water uptake,and changes in the flexural strength during water absorption of C_3D/EP composites have been studied in the water absorption experiment. Experiment results show that the equilibrium moisture content of the C_3D/EP composites is lower than that of unreinforced epoxy resin but slightly higher than that of the long carbon fiber reinforced epoxy resin(C_L/EP)composites. The absorption behavior at the initial stage conforms to Fick's law of diffusion while the whole absorption behavior of epoxy resin composites can be described with the Sigmoidal model. The flexural strength of the C_3D/EP composites decreases quickly with immersion time at the early stage and then levels off,which is in agreement with the absorption content-time curve. It is also found that temperature affects the absorption process greatly. The absorption rate and equilibrium moisture content of the C_3D/EP composites increase with the rise of temperature. The higher the tempera-ture,more remarkable the loss of flexural strength. It is thus concluded that the reduction of mechanical property is related to the water absorption content of the C_3D/EP composites.%为了研究三维编织复合材料的吸湿行为,利用树脂传递模塑(RTM)工艺制备了三维编织炭纤维增强环氧树脂(C3D/EP)复合材料.通过吸水实验,研究了该材料的吸湿规律、温度对吸湿的影响以及吸湿过程中复合材料力学性能的变化.结果表明:C_(3D)/EP复合材料吸湿初期符合Fick扩散定律,但整个吸湿行为可用Sigmoidal曲线来描述;温度可加速C_(3D)EP复合材料的吸湿速率,并使平衡吸湿量提高;在吸湿过程中,C_(3D)EP复合材料的弯曲强度随吸湿时间的延长而下降.先快后慢,与吸湿曲线相对应,而且温
Braid My Hair - Randy Owen sings out for sick children
... hair due to illness. Chris Gray and Brent Wilson wrote the song. Gray had been a teacher at St. Jude helping kids there who were being treated for cancer and other catastrophic childhood diseases. He knew firsthand the effects chemotherapy had on kids and that many of ...
Numerical Simulations of Coronal Heating through Footpoint Braiding
Hansteen, Viggo; De Pontieu, Bart; Carlsson, Mats
2015-01-01
Advanced 3D radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are self-consistently maintained. Here we study two realistic models, with different simulated area, magnetic field strength and topology, and numerical resolution. These are compared in order to characterize the heating in the 3D-MHD simulations which self-consistently maintains the structure of the atmosphere. We analyze the heating at both large and small scales and find that heating is episodic and highly structured in space, but occurs along loop shaped structures, and moves along with the magnetic field. On large scales we find that the heating per particle is maximal near the transition region and that widely distributed opposite-polarity field in the photosphere leads to a greater heating scale height in the corona. On smaller scales, heating is concentrated in current sheets, the thicknesses of which are set ...
Particle Identifications from Symmetries of Braided Ribbon Network Invariants
Bilson-Thompson, Sundance; Kauffman, Lou; Smolin, Lee
2008-01-01
We develop the idea that the particles of the standard model may arise from excitations of quantum geometry. A previously proposed topological model of preons is developed so that it incorporates an unbounded number of generations. A condition is also found on quantum gravity dynamics necessary for the interactions of the standard model to emerge.
HOMFLY polynomials in representation [3, 1] for 3-strand braids
Mironov, A.; Morozov, A.; Morozov, An.; Sleptsov, A.
2016-09-01
This paper is a new step in the project of systematic description of colored knot polynomials started in [1]. In this paper, we managed to explicitly find the inclusive Racah matrix, i.e. the whole set of mixing matrices in channels R ⊗3 -→ Q with all possible Q, for R = [3 , 1]. The calculation is made possible by the use of a newly-developed efficient highest-weight method, still it remains tedious. The result allows one to evaluate and investigate [3 , 1]-colored polynomials for arbitrary 3-strand knots, and this confirms many previous conjectures on various factorizations, universality, and differential expansions. We consider in some detail the next-to-twist-knots three-strand family ( n, -1 | 1 , -1) and deduce its colored HOMFLY. Also confirmed and clarified is the eigenvalue hypothesis for the Racah matrices, which promises to provide a shortcut to generic formulas for arbitrary representations.
Directory of Open Access Journals (Sweden)
Luiz Eduardo Carvalho Buquera
2002-02-01
Full Text Available A ruptura do ligamento cruzado cranial é uma das principais doenças ortopédicas que afetam os cães. Muitas técnicas cirúrgicas foram descritas no intuito de aliviar a dor, restaurar a estabilidade biomecânica do joelho e prevenir a progressão da osteoartrite. Fáscia lata, fio de poliéster trançado e fio de poliamida foram empregados na estabilização do joelho após excisão do ligamento cruzado cranial em cães, os quais foram submetidos à avaliação radiográfica e macroscópica da articulação. Neste estudo, foram utilizados 18 cães com massa corporal superior a 15Kg (peso médio - 19,67kg, separados em 3 grupos eqüitativos correspondentes a cada técnica, avaliados durante 30 e 60 dias. Ao exame radiográfico, independentemente de grupo, os cães apresentaram evidência de efusão articular moderada a severa, distensão da cápsula articular e, na maioria dos casos, ausência de sinais de doença articular degenerativa. Ao exame macroscópico da articulação do joelho observou-se espessamento da cápsula articular e tecidos moles periarticulares, erosão da cartilagem articular dos côndilos femorais em todos os grupos e afrouxamento dos fios nos cães submetidos às técnicas de estabilização extra-articular com fio de poliéster trançado e fio de poliamida.The cranial cruciate ligament rupture is one of the main orthopaedic diseases which affect dogs. Many surgical techniques have been described and they aim to relief the pain, restore stifle biomechanical stability and prevent the progression of osteoarthritis. Fascia lata, braided polyester and polyamida were used in lateral fabellar suture to stifle stabilization after induced cranial cruciate ligament rupture in dogs that were submitted to radiographic and macroscopic evaluation of joint. In this study 18 dogs weighting more than 15kg were used (middleweight - 19.67kg, distributed in three groups corresponding to each technique, evaluated during 30 and 60 days. In
Braided Reach Cross-Section Monitoring Surveys, Kootenai River near Bonners Ferry, Idaho, 2011
U.S. Geological Survey, Department of the Interior — In 2009, the Kootenai Tribe of Idaho released and implemented the Kootenai River Habitat Restoration Master Plan. This plan aimed to restore, enhance, and maintain...
Braiding and Rhetorical Power Players: Transforming Academic Writing through Rhetorical Dialectic
Gunter, Kimberly K.
2011-01-01
In this article, I revisit the Elbow/Bartholomae debate, review recent scholarship on academic writing, and discuss the ways that the mandates of traditional academic writing can further disenfranchise already marginalized students. I suggest that, due to the double consciousness with which these students often live, they come into classrooms…
Quantum Racah matrices and 3-strand braids in irreps R with |R|=4
Mironov, A; Morozov, An; Sleptsov, A
2016-01-01
We describe the inclusive Racah matrices for the first non-(anti)symmetric rectangular representation R=[2,2] for quantum groups U_q(sl_N). Most of them have sizes 2, 3, and 4 and are fully described by the eigenvalue hypothesis. Of two 6x6 matrices, one is also described in this way, but the other one corresponds to the case of degenerate eigenvalues and is evaluated by the highest weight method. Together with the much harder calculation for R=[3,1] in arXiv:1605.02313 and with the new method to extract exclusive matrices S and \\bar S from the inclusive ones, this completes the story of Racah matrices for |R|\\leq 4 and allows one to calculate and investigate the corresponding colored HOMFLY polynomials for arbitrary 3-strand and arborescent knots.
The braid group representation on intersection matrices and monodromy of singularities
Dietz, G. (Gunnar)
2005-01-01
Es ist bekannt, dass die Monodromie der Milnor-Faserung einer isolierten Singularität quasiunipotent ist. Dies ist nicht länger der Fall, wenn man eine nicht-lokale Monodromie um mehrere Singularitäten betrachtet. Wir studieren hier den Fall von Familien von (endlich vielen) Morse-Singularitäten. Für den Fall, dass eine solche Familie eine Morsifikation einer isolierten Singularität ist, zeigen wir, dass sämtliche Monodromien, die zu einfachen Schleifen um eine Teilfamilie der zugehörigen kri...
Blood-Flow Modelling Along and Trough a Braided Multi-Layer Metallic Stent
Milisic, Vuk
2009-01-01
In this work we study the hemodynamics in a stented artery connected either to a collateral artery or to an aneurysmal sac. The blood flow is driven by the pressure drop. Our aim is to characterize the flow-rate and the pressure in the contiguous zone to the main artery: using boundary layer theory we construct a homogenized first order approximation with respect to epsilon, the size of the stent's wires. This provides an explicit expression of the velocity profile through and along the stent. The profile depends only on the input/output pressure data of the problem and some homogenized constant quantities: it is explicit. In the collateral artery this gives the flow-rate. In the case of the aneurysm, it shows that : (i) the zeroth order term of the pressure in the sac equals the averaged pressure along the stent in the main artery, (ii) the presence of the stent inverses the rotation of the vortex. Extending the tools set up in [Bonnetier et al, Adv. Math. Fluids, 2009, Milisic, Meth. Apl. Ann., 2009] we pro...
HOMFLY polynomials in representation [3,1] for 3-strand braids
Mironov, A; Morozov, An; Sleptsov, A
2016-01-01
This paper is a new step in the project of systematic description of colored knot polynomials started in arXiv:1506.00339. In this paper, we managed to explicitly find the inclusive Racah matrix, i.e. the whole set of mixing matrices in channels R^3->Q with all possible Q, for R=[3,1]. The calculation is made possible by the use of a newly-developed efficient highest-weight method, still it remains tedious. The result allows one to evaluate and investigate [3,1]-colored polynomials for arbitrary 3-strand knots, and this confirms many previous conjectures on various factorizations, universality, and differential expansions. We consider in some detail the next-to-twist-knots three-strand family (n,-1|1,-1) and deduce its colored HOMFLY. Also confirmed and clarified is the eigenvalue hypothesis for the Racah matrices, which promises to provide a shortcut to generic formulas for arbitrary representations.
Quantum Racah matrices and 3-strand braids in irreps R with |R| = 4
Mironov, A.; Morozov, A.; Morozov, An.; Sleptsov, A.
2016-07-01
We describe the inclusive Racah matrices for the first non-(anti)symmetric rectangular representation R = [2, 2] for quantum groups U q (sl N ). Most of them have sizes 2, 3, and 4 and are fully described by the eigenvalue hypothesis. Of two 6 × 6 matrices, one is also described in this way, but the other one corresponds to the case of degenerate eigenvalues and is evaluated by the highest weight method. Together with the much harder calculation for R = [3, 1] and with the new method to extract exclusive matrices S and bar S from the inclusive ones, this completes the story of Racah matrices for |R| ≤ 4 and allows one to calculate and investigate the corresponding colored HOMFLY polynomials for arbitrary 3-strand and arborescent knots.
EDDY CURRENT SYSTEM FOR DETECTION OF CRACKING BENEATH BRAIDING IN CORRUGATED METAL HOSE
International Nuclear Information System (INIS)
In this paper an eddy current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing technique is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.
Ballistic and Cyclic Rig Testing of Braided Composite Fan Case Structures
Watson, William R.; Roberts, Gary D.; Pereira, J. Michael; Braley, Michael S.
2015-01-01
FAA fan blade-out certification testing on turbofan engines occurs very late in an engine's development program and is very costly. It is of utmost importance to approach the FAA Certification engine test with a high degree of confidence that the containment structure will not only contain the high-energy debris, but that it will also withstand the cyclic loads that occur with engine spooldown and continued rotation as the non-running engine maintains a low rotor RPM due to forced airflow as the engine-out aircraft returns to an airport. Accurate rig testing is needed for predicting and understanding material behavior of the fan case structure during all phases of this fan blade-out event.
Bending response of 3-D woven and braided preform composite materials
Energy Technology Data Exchange (ETDEWEB)
Pochiraju, K.; Parvizi-Majidi, A.; Chou, T.W. [Univ. of Delaware, Newark, DE (United States); Shah, B. [Lockheed Aeronautical Systems Company, Marietta, GA (United States)
1994-12-31
Three dimensional textile carbon-epoxy composites exhibit general anisotropy. Further, these materials may possess different modulus in uniaxial tension than that in compression. In an earlier material characterization effort, the tension, compression, and shear properties of these composites were determined. In this paper, theoretical modeling of flexure of the textile composites and experimental correlation are presented. Four point bending tests were conducted according to STM D709 standards to determine the load to mid-span deflection relationships for typical textile composites. The results of experimental analysis are compared with classical beam theory, theory of elasticity solutions considering material orthotropy and shear deflection, and finite element analysis considering material orthotropy and finite deformation/rotations. The derivation of a harmonic function, required for the theory of elasticity solution, is described in the paper. Homogeneous orthotropic elastic properties are assumed for the 3-D textile composites, which is a reasonable approximation for specimens considerably larger than the repeated geometric unit of the fiber preform. The so called ``flex modulus`` is determined from the experimental data.
Avrin, Jack
2015-01-01
Elementary particles in this book exist as Solitons in-and-of the fabric of spacetime itself. As such they are characterized by their geometry, that is their topology and configuration which lead directly to their physical attributes and behavior as well as to a simplification and reduction of assumptions and the importation of parameter values. The emphasis of the book is thus on that geometry, the algebraic geometry associated with taxonomical issues and the differential geometry that determines the physics as well as on simplifying the results. In itself, however, the process of assembling and developing what eventually went into the book has been a singularly rewarding journey. Along the way some fascinating insights and connections to known physical attributes and theories emerge, some predictable but others unbidden and even unanticipated. The book is intended to summarize that journey in a way that, readers with a range of backgrounds will find interesting and provocative. Connections to other physical...
Directory of Open Access Journals (Sweden)
Rubio, V.
1997-12-01
Full Text Available The physico-chemical and mineralogical study of the Ara river sediments, in the Central Pyrenees (Spain, allows to recognize the genesis and evolution of its basin. The minerals of the sand fraction, the ones corresponding to the clay fraction and the minority elements, reveal certain processes and associations that, in addition to the identification of the fluvial terraces, fans, glacis and even morainic deposits, contribute to explain the geological history of the Central Pyrenees, the main objective of this work. The application of a multivariate factorial analysis to the data with BMDP-4M program was very helpful for the interpretation of the results. The more resistant minerals are found in the thinner textural fractions, whereas the more alterable are located in the thicker fractions. The cones and glacis, composed by materials of the flysch, reveal an alteration of the carbonated materials which is shown by the formation of feldspars and anphybols. The formation of iron and manganese metal oxides, of different crystallinity degrees, associated with chrome, lead and nickel, is also observed. The morainic deposits, mainly composed by silicate materials, bring along the formation of illite associated with copper and zinc. Finally, the fluvial terraces have a combination of both alteration processes previously described.
[es] El estudio físico-químico y mineralógico de los sedimentos del río Ara, en el Pirineo Central (España, permite reconocer la génesis y evolución de su cuenca. Los minerales de la fracción arena, los correspondientes a la fracción arcilla y los elementos minoritarios, delatan ciertos procesos y asociaciones que, junto con la identificación de terrazas fluviales, conos, glacis e incluso depósitos morrénicos, ayudan a explicar la historia geológica del Pirineo Central, principal objetivo de este trabajo. La aplicación al conjunto de datos de un análisis factorial multivariante mediante el programa BMDP-4M facilitó la interpretación de los resultados. Los minerales más resistentes se encuentran en las fracciones texturales más finas, mientras que los minerales más alterables se localizan en las más gruesas. Los conos y glacis constituidos por materiales del flysch, presentan una alteración de materiales carbonatados que se manifiesta por la formación de esmectita y sepiolita en la fracción arcilla como resultado de la transformación de feldespatos y anfíboles. También se observa la formación de óxidos de hierro y manganeso con distinto grado de cristalinidad asociados a cromo, plomo y níquel. Las morrenas constituidas principalmente por materiales silicatados conllevan la formación de Hita asociada a cobre y zinc. Por último, las terrazas fluviales tienen mezcla de los procesos de alteración anteriormente descritos.
[fr] L'étude physique, chimique et minéralogique des sédiments de la rivière Ara, dans les Pyrénées Centrales (Espagne permet de reconnaître la genèse et l'évolution de son bassin. Les minéraux à la fraction sableuse, ceux qui correspondent à la fraction de l'argile et les éléments chimiques minoritaires, démontrent quelques procès et des associations en relation avec l'identification des terrasses fluviaux, des cônes, des glacis et des dépôts morainiques, aident à expliquer l'histoire géologique des Pyrénées Centrales, ce qui est le principal objectif de ce travail. L'application des données d'un analyse factoriel multivariant grâce au programme BMDP-4M facilite l'interprétation des résultats. Les minéraux le plus résistent se trouvent dans les fractions les plus fines, et les minéraux les plus altérables se situent aux plus lourdes. Les cônes et les glacis formés pour les matériaux du flysch, montraient une altération des carbonates qui finissent dans la formation de la smectite et de la sepiolite à la fraction argileuse comme un résultat de la transformation des feldspaths et des amphibols. Aussi on voit la formation des oxydes defer et de manganèse avec différent degré de cristallinité, associés au Cr, Pb et Ni. Les moraines formées par les matériaux silicates conduisent à la formation de l'illite avec le Cu et le Zn. Les terrasses fluviaux montrent une mélange des procès d'altération avant décrits.
Godelle, Eddy
2010-01-01
Let $\\Gamma$ be a Coxeter graph, let $(W,S)$ be its associated Coxeter system, and let $(A,\\Sigma$) be its associated Artin-Tits system. We regard $W$ as a reflection group acting on a real vector space $V$. Let $I$ be the Tits cone, and let $E_\\Gamma$ be the complement in $I +iV$ of the reflecting hyperplanes. Recall that Charney, Davis, and Salvetti have constructed a simplicial complex $\\Omega(\\Gamma)$ having the same homotopy type as $E_\\Gamma$. We observe that, if $T \\subset S$, then $\\Omega(\\Gamma_T)$ naturally embeds into $\\Omega (\\Gamma)$. We prove that this embedding admits a retraction $\\pi_T: \\Omega(\\Gamma) \\to \\Omega (\\Gamma_T)$, and we deduce several topological and combinatorial results on parabolic subgroups of $A$. From a family $\\SS$ of subsets of $S$ having certain properties, we construct a cube complex $\\Phi$, we show that $\\Phi$ has the same homotopy type as the universal cover of $E_\\Gamma$, and we prove that $\\Phi$ is CAT(0) if and only if $\\SS$ is a flag complex. We say that $X \\subset...
Partial Doi-Hopf模的辫子Monoidal范畴%Braid Monoidal Category of Partial Doi-Hopf Modules
Institute of Scientific and Technical Information of China (English)
姜秀燕; 贾玲
2010-01-01
通过引入Monoidal Partial Doi-Hopf数组和模的概念及例子,得到Partial Doi-Hopf模范畴是一个Monoidal范畴. 在此基础上根据多种重要模范畴的辫子结构构造了此范畴的辫子,并得到了使Partial Doi-Hopf模范畴成为辫子 Monoidal范畴的充要条件.
Crosato, A.; Mosselman, E.
2009-01-01
The number of bars that form in an alluvial channel cross section can be determined from a physics-based linear model for alluvial bed topography. The classical approach defines separators between ranges in which river planform styles with certain numbers of bars are linearly stable and linearly uns
de Wet, A. P.; Bleacher, J. E.; Garry, W. B.
2012-01-01
Water has clearly played an important part in the geological evolution of Mars. There are many features on Mars that were almost certainly formed by fluvial processes -- for example, the channels Kasei Valles and Ares Vallis in the Chryse Planitia area of Mars are almost certainly fluvial features. On the other hand, there are many channel features that are much more difficult to interpret -- and have been variously attributed to volcanic and fluvial processes. Clearly unraveling the details of the role of water on Mars is extremely important, especially in the context of the search of extinct or extant life. In this project we built on our recent work in determining the origin of one channel on the southwest rift apron of Ascraeus Mons. This project, funded by the Keck Geology Consortium and involving 4 undergraduate geology majors took advantage of the recently available datasets to map and analyze similar features on Ascraeus Mons and some other areas of Mars. A clearer understanding of how these particular channel features formed might lead to the development of better criteria to distinguish how other Martian channel features formed. Ultimately this might provide us with a better understanding of the role of volcanic and fluvial processes in the geological evolution of Mars.
Effects of different coagulant enzymes used on quality of traditional Örgü cheese (Braided cheese
Directory of Open Access Journals (Sweden)
Mehmet Çelebi
2015-02-01
Full Text Available In this study, Örgü cheese has been produced by using different coagulating enzymes (calf rennet, microbial enzymes, recombinant chymosin. The effects of different coagulating enzymes which are used on the characteristic of mineral material and cheese has been observed during 90 days ripening time. Mineral material contents of Örgü cheese have been determined with ICP-OES (inductively coupled plasma optical emission spectroscopy. Proteolysis levels of cheese have been observed with chemical analysis and help of SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis. The determined difference between analysis results, titratable acidity, total nitrogen, water soluble nitrogen, ripening index, total solid, fat, fat in total solid, salt, salt in total solid, ash, texture, mineral material (Ca, Fe, Cu, Al, Mg, Mn of Örgü cheese’s analysis result haven’t been regarded as significant statistically. Each of enzymes which are used effects similarly on α-casein and β-casein during the ripening time and each of the ratios which are gained have been closely determined.
US Fish and Wildlife Service, Department of the Interior — Appendix A contains the data which met QA/QC criteria. Concentrations (ppm) for each element are individually tabulated. Values for sediment, total waters,...
构建和谐团队 促进社会工作%Braiding a Harmonious Team,Promoting Social work
Institute of Scientific and Technical Information of China (English)
林嫦
2012-01-01
In social work,the team plays a more and more important role.The paper expounds on the influence of the team and the individual in social work, analyzes several aspects that is disadvantageous to team construction in social work,and puts forward approaches to construct a harmonious team and promote social work:self-awareness,inter-admission,integration of individual work and team cooperation, giving full play to the important role of team leader, strengthening training.%在社会工作中,团队发挥出越来越重要的作用,文章试述团队和个人在社会工作中的影响,分析社会工作中不利于团队建设的几种表现,提出构建和谐团队,促进社会工作的途径：自我认知,清晰自己的角色和定位;相互接纳,善于沟通协调;既要有分工更要有合作;充分发挥团队领头人的重要作用;加强培训,造就一支结构合理、素质优良的社会工作人才队伍。
MOSSI ALBIACH, ALEJANDRO
2016-01-01
[EN] KAT1 is an Arabidopsis thaliana potassium voltage-gated channel of the Shaker family. This ion channel is fundamental for the control of membrane conductance in guard cells, leading to stomatal opening or closing in response to environmental changes. The stomatal movement controls the gas exchange, as well as the amount of water lost due to transpiration. Therefore, the underlying mechanisms of these stomatal movements will likely be influenced by proteins that regulate KAT1 ...
Long, Ada, Ed.
2014-01-01
City as Text™ (CAT) is one of the earliest structural forms of experiential learning created and practiced in the United States. This monograph explores the centrality of writing in the process of active learning, focusing primarily on the Faculty Institutes and Honors Semesters that foster CAT experiences. All manifestations of this pedagogical…
Application of adhesive XS-100 in fiber braided hose%粘合剂XS-100在纤维编织胶管中的应用
Institute of Scientific and Technical Information of China (English)
丁庆凯
2008-01-01
试验研究粘合剂XS-100在纤维编织胶管中的应用.结果表明,粘合剂XS-100用量对胶管胶料的物理性能影响不大,当粘合剂XS-100用量为5份时硫化胶的粘合性能最好;以粘合剂XS-100等量替代粘合剂RS/A,胶管胶料的物理性能和粘合性能变化不大,耐热空气老化性能略有提高,成品胶管符合企业标准要求.
Analysis of Facet-braiding Based on 3D Reconstruction of Integral Imaging%基于Ⅱ三维重建的facet-braiding现象分析
Institute of Scientific and Technical Information of China (English)
王红霞
2010-01-01
三维全景图像技术(Integral Imaging,简称Ⅱ)是一种能够记录和显示全真三维场景的图像技术.该技术采用微透镜阵列记录空间场景,空间任意一点的深度信息只需通过一次成像即可直接获得.Facet-braiding是三维全景图像中一种很重要的视觉现象,该现象造成图像失真,影响了图像的观看效果.Ref.6中Martinez-Cuenca从单个元素图像的角度对该现象进行了分析,现从三维重建的角度对该现象的出现与否进行对比验证.先用光学软件模拟深度优先、参考平面在无穷远处的传统Ⅱ成像系统,然后在该模拟系统中进行对比实验,结果并未出现Ref.6中提到的facet-braiding现象.该结果对Ⅱ的视角分析、物体的精确三维重建及空间分辨率分析具有重要意义.
The Artistic Edification of The Magic Braid, the Pursuit of Perfectionism Elements%《神鞭》的艺术启示
Institute of Scientific and Technical Information of China (English)
彭晓农; 喻俊明
2008-01-01
在20世纪80年代的通俗文学中的武侠传奇热中,曾产生了一批通俗文学.冯骥才的,把浓郁的传奇性和可贵的现代意识把握有机结合,令人耳目一新,并在通俗文学向何处去上给人以启迪.
Hybrid composite rods for concrete reinforcement
Fangueiro, Raúl; Pereira, Cristiana Gonilho; Jalali, Said; Araújo, Mário Duarte de; Marques, P.
2010-01-01
The current work is concerned with the development of braided composite rods for civil engineering applications, namely for concrete internal reinforcement, as a steel substitute. The research study aims at understanding the tensile behaviour of composite rods reinforced by a textile structure – braided structure with core reinforcement.Seven types of braided composite rods were produced, varying the type of fibres used as a core reinforcement of a polyester braided structure. ...
Topological Quantum Hashing with the Icosahedral Group
Burrello, Michele; Xu, Haitan; Mussardo, Giuseppe; Wan, Xin
2010-04-01
We study an efficient algorithm to hash any single-qubit gate into a braid of Fibonacci anyons represented by a product of icosahedral group elements. By representing the group elements by braid segments of different lengths, we introduce a series of pseudogroups. Joining these braid segments in a renormalization group fashion, we obtain a Gaussian unitary ensemble of random-matrix representations of braids. With braids of length O(log2(1/ɛ)), we can approximate all SU(2) matrices to an average error ɛ with a cost of O(log(1/ɛ)) in time. The algorithm is applicable to generic quantum compiling.
DEFF Research Database (Denmark)
Bashforth, Arden Roy; Drábková, Jana; Opluštil, Stanislav;
2011-01-01
to avulsion and flooding. Taphonomic observations and multivariate analysis of 41 quadrats containing mostly (par)autochthonous megafloral assemblages reveal that riparian vegetation comprised a collage of monospecific to low-diversity communities, with patchiness prevalent at local and regional scales...
三维编织炭纤维/环氧复合材料的性能研究%STUDY ON MECHANICAL PROPERTIES OF 3D BRAIDED CARBON FIBER/EPOXY COMPOSITE
Institute of Scientific and Technical Information of China (English)
王玉果; 王玉林; 万怡灶
2000-01-01
采用真空浸渍工艺,成功地制备了三维编织炭纤维/环氧复合材料,并用金相显微镜对微观结构进行了观察,发现基体与纤维间浸润良好.力学试验表明,该材料具有良好的力学性能,是一种极有发展潜力的复合材料.
Tribological Properties of 3D Braided Carbon Fiber/Epoxy Composites%三维编织碳/环氧复合材料的摩擦学特性
Institute of Scientific and Technical Information of China (English)
王玉果; 王玉林
2005-01-01
为研究三维编织复合材料的摩擦学行为,采用RTM工艺制备了三维编织碳纤维增强环氧树脂复合材料,讨论了纤维体积比、纤维表面处理和润滑条件等因素对复合材料摩擦磨损性能的影响.结果表明,随着纤维含量的增加,复合材料的摩擦系数先降后升,在35%时有最小值;磨损率则一直下降.纤维表面处理使复合材料的磨损率降低,耐磨性提高.水润滑条件下复合材料的摩擦磨损性能远优于干摩擦条件下的性能.干摩擦条件下复合材料的磨损机制主要为黏着磨损,水润滑条件下则以磨粒磨损为主.
Institute of Scientific and Technical Information of China (English)
王国军; 孙颖; 李嘉禄
2009-01-01
本文采用超声回波法对碳/环氧三维编织复合材料进行超声A-扫描,结合对超声定位的缺陷区域进行细现形貌解剖分析,研究了超声回波波形和三维编织复合材料细现形貌特征的对应关系.在考虑碳纤维单丝分布及纤维束和树脂界面状态的基础上,利用经验的波形分析法讨论了超声波在三维编织复合材料中的衰减.实验研究结果表明,超声回波特征和三维编织复合材料缺陷有对应关系,超声A-扫描波形特征分析可用于碳/环氧三维编织复合材料的无损检测及其缺陷的初步评价.
Institute of Scientific and Technical Information of China (English)
张芳芳; 刘才
2014-01-01
基于区域叠合技术和与材料断裂能相关的损伤演化模型对三维四向编织复合材料的渐进损伤演变过程及拉伸强度进行数值预测.结合基于Fortran语言编写的单胞增强相网格提取算法,实现了参数化单胞增强相网格模型的快速建立.基于Murakami损伤理论建立了正交各向异性损伤本构模型,利用等价位移控制相应模式下损伤的演变发展,分别模拟了典型大小编织角三维四向编织复合材料的细观损伤起始、扩展和最终失效过程.数值预测结果与实验结果吻合较好.
Institute of Scientific and Technical Information of China (English)
陈利; 詹丽丽; 孙颍
2007-01-01
在渐近均匀化理论基础上,确立了基于单胞数字化模型的复合材料宏观等效弹性性能的三维数值分析方法(DCB-FEA).该方法采用三维光栅化技术将三维单胞模型转化为三维光栅图形(数字化模型),并将光栅图形直接转化为三维有限元求解网格.产生的离散单元具有相同的几何尺寸和规则的形状,单元刚度矩阵的数量将减少为单胞材料的个数.此外,单胞数字化模型仅需记录每个离散单元的材料种类,其他参数如单元节点编号、节点坐标等均可在求解过程中自动生成,周期性边界条件也可以自动施加.随着分辨率的提高,单胞数字化模型将产生更多数量的单元,特别是对于三维单胞模型,集成整体刚度矩阵时需要大量的计算机内存.采用基于Element-by-element策略的预处理共轭梯度法(EBE-PCG),有限元方程的求解在单元级上进行,避免了整体刚度矩阵的集成.通过对三维编织复合材料的线弹性本构关系的数值模拟,表明该方法可得到较为准确的复合材料等效模量.
Excellent bonding behaviour of novel surface-tailored fibre composite rods with cementitious matrix
Indian Academy of Sciences (India)
Fernando Cunha; Sohel Rana; Raul Fangueiro; Graça Vasconcelos
2014-08-01
Novel composite rods were produced by a special braiding technique that involves braiding of polyester yarns around a core of resin-impregnated carbon fibres and subsequent curing. The surface roughness of these braided rods was tailored by replacing one or two simple yarns in the outer-braided layer with braided yarns (produced from 8 simple yarns) and adjusting the take-up velocity. Pull-out tests were carried out to characterize the bond behaviour of these composite rods with cementitious matrix. It was observed that the rod produced with two braided yarns in the outer cover and highest take-up speed was ruptured completely before pull-out, leading to full utilization of its tensile strength, and exhibited 134% higher pull-out force as compared to the rods produced using only simple braiding yarns.
2010-10-01
... performing the inspection, the hose assembly identification number, the company name, the date the hose was... to the hose cover that exposes the reinforcement. (ii) Wire braid reinforcement that has been kinked... section. (v) Stainless steel flexible connectors with damaged reinforcement braid. (vi) Internal...
Self-monitoring Composite Rods for Sustainable Construction
Gonilho-Pereira, Cristiana; Zdraveva, Emilija; Fangueiro, Raul; Lanceros-Mendez, S.; Jalali, Said; de Araújo, Mário
This paper presents the development and properties assessment of braided reinforced composite rods (BCR) able to both reinforce and monitor the stress state of concrete infrastructures. The research study aims at understanding the tensile behaviour and self-monitoring ability of composite rods reinforced by a textile structure - braided structure with core reinforcement - for civil engineering applications, namely for concrete internal reinforcement, as a steel substitute, in order to improve structures safety and sustainability. Seven types of braided composite rods have been produced using an author patented technique based on a modified conventional braiding machine. The tensile properties of the braided reinforced composite rods were evaluated in order to identify the type(s) of fibre(s) to be used as core reinforcement. BCR have been tested under bending while the variation of the electrical resistance was simultaneously monitored.
Institute of Scientific and Technical Information of China (English)
卢子兴; 王成禹; 夏彪
2014-01-01
基于三维全五向(Q5D)编织复合材料的细观结构模型,通过引入界面相单元,建立了含界面相Q5D编织复合材料单轴拉伸损伤失效分析模型.应用Python语言实现对ABAQUS的二次开发,将Linde等提出的失效准则和Von-Mises应力准则分别用于纱线和基体的渐进损伤判断,并确定材料的整体失效模式;对于界面相,采用Quads准则进行损伤判断.利用周期性位移边界条件,对含界面相Q5D编织复合材料的纵向拉伸应力-应变行为进行了渐进损伤数值模拟,详细讨论了在纵向拉伸载荷作用下材料的细观损伤起始、扩展和最终失效的演化过程,分析了材料的细观损伤失效机制,预测了材料的极限破坏强度,并研究了界面相性能对材料整体力学行为的影响规律.研究结果表明,数值模拟结果与实验值吻合较好,验证了渐进损伤模型的有效性,为该类材料的力学分析和优化设计奠定了基础.
Institute of Scientific and Technical Information of China (English)
陈凯; 李旭东; 李鹏飞
2010-01-01
三维编织C/C复合材料在制备过程时会存在于基体中,纤维上的缺陷以及界面相的异构.从界面相的异构出发,通过计算机来模拟带有界面相异构的三维编织C/C复合材料模型,预测复合材料在具有界面相异构下的结果,为研究具有不同形式微结构的编织复合材料本构关系,预测编织复合材料的弹性力学行为,搞清不同微结构对应的破坏模式和破坏机理提供参考.
Institute of Scientific and Technical Information of China (English)
谢辉
2004-01-01
焉耆盆地宝浪油田含油气层段位于中生界下侏罗统三工河组(J1s),为典型的浅水缓坡型粗粒辫状河三角洲-湖泊沉积体系.储层成分成熟度和结构成熟度低,粒度概率曲线以牵引和悬浮二段式为主,C -M图以PQ段和QR段为主,宝浪油田侏罗系三工河组划分出12种有成因意义的岩石相,采用Coleman的方案将浅水辫状河三角洲划分为:上三角洲平原(洪水线之上)、下三角洲平原(枯水线-洪水线之间)和水下三角洲平原(枯水线之下)3个亚相带.研究区主要发育了(水下)分流河道微相、水下分流河道间微相、决口水道(扇)微相、溢流沉积微相、滨湖沼泽沉积微相,河口坝微相不发育.(水下)分流河道微相占研究区储层的90%以上,根据砂体的岩石相组合、冲刷程度、水流能量大小的变化规律,其又可分为:充填河道、废弃河道、进积河道3种基本类型.储层物性以废弃河道为最好,单井油气产能亦最高,充填河道次之,进积河道和决口水道(扇)则相对较差.
Institute of Scientific and Technical Information of China (English)
方丹丹; 阎建华
2014-01-01
该文研究了三维五向玻纤/碳纤编织混杂复合材料的冲击性能和冲击后弯曲性能,对试样分别进行了落锤冲击试验和三点弯曲试验.研究表明,通过落锤冲击试样发现,冲击后冲击面的损伤比背面的损伤低,冲击背面裂纹主要沿纵向扩展;通过弯曲性能测试得出碳纤维的加入使玻璃纤维复合材料的弯曲模量提高;当轴纱排布为CF∶ GF∶ CF时,混杂复合材料的抗冲击性能最好,材料的抗冲击性能与混杂方式有关.
Institute of Scientific and Technical Information of China (English)
何芳; 王玉林; 万怡灶; 黄远
2008-01-01
采用复合处理工艺对三维混杂超高分子量聚乙烯纤维/碳纤维编织体进行表面处理,通过RTM工艺制备了环氧树脂基混杂复合材料(UHMWPE/CF/ER),并研究了其力学性能及混杂效应.结果表明,在纤维总体积分数一定的情况下,随着超高分子量聚乙烯纤维/碳纤维混杂比的减小,复合材料的弯曲强度、弯曲模量及压缩强度增大,而其纵向剪切强度及冲击韧性降低.三维编织混杂复合材料的断裂机制由混杂纤维的混杂比及其性质决定,通过调节混杂比可实现对复合材料力学性能的有效调控.
Institute of Scientific and Technical Information of China (English)
何芳; 王玉林; 万怡灶; 黄远
2009-01-01
以超高分子量聚乙烯纤维(UHMWPE)-碳纤维(CF)三维混杂编织体为增强体,环氧树脂(ER)为基体,通过树脂传递模塑(RTM)工艺制备了三维编织混杂复合材料,研究了其摩擦磨损性能,并采用混合正压力模型对摩擦系数进行了预测.结果表明,在纤维总体积含量一定的情况下,随着CF体积含量的增加,复合材料的摩擦系数增大,而其比磨损率降低.UH3D/ER复合材料的磨损机制以粘着磨损为主,CF3D/ER复合材料则以磨粒磨损为主,混杂复合材料的磨损机制主要取决于CF与UHMWPE纤维的相对含量,通过调节UHMWPE纤维和CF的体积比例可实现对复合材料摩擦磨损性能的有效调控.采用的计算模型可较好地预测UH3D/ER的摩擦系数.
Institute of Scientific and Technical Information of China (English)
徐孝诚; 孙鹏军; 马斌捷; 陈小庆
2002-01-01
本文给出了两个三维四向整体编织碳/环氧复合材料圆锥壳体临界外压的试验结果,进一步验证了三维四向整体编织复合材料壳体临界外压计算方法.计算结果与试验结果相符较好,计算时试验修正系数可取0.8.
Institute of Scientific and Technical Information of China (English)
孙颖; 陈利; 李嘉禄
2008-01-01
对三维多向编织复合材料圆管相贯型接头进行材料设计.从采用微观力学反算法确定组分材料性能出发,由刚度平均化方法基于单胞模型确定复合材料的本构特性,利用Patran/Marc对炭/环氧三维多向编织复合材料圆管相贯型接头的承载性能进行有限元应力分析,讨论细观结构形式和编织角对接头结构受力变形行为的影响.结果表明,大编织角三维六向编织复合材料的特性更接近各向同性,有利于提高接头的承载性能均衡性,该分析方法和结果为三维异型整体多向编织复合材料结构的材料设计提供参考.
Institute of Scientific and Technical Information of China (English)
王玉果; 王玉林; 万怡灶; 董向红
2001-01-01
在对长碳纤维/环氧复合材料(C1/Ep)研究的基础上，重点研究了纤维空气氧化和次氯酸钠氧化对三维编织碳纤维/环氧复合材料(C3D /Ep)力学性能的影响。结果表明.纤维表面处理可显著增强纤维/基体的界面结合强度.使其力学性能大幅度提高。其中.空气氧化效果最为明显。
Institute of Scientific and Technical Information of China (English)
庞宝君; 杜善义; 韩杰才; 王铎
2000-01-01
针对三维多向编织复合材料,在已建立的单胞几何模型及材料力学性能细观计算力学分析方法的基础上,引入Murakami的几何损伤理论模拟纤维束的细观损伤行为,建立了预报该类材料非线性本构行为数值模拟及细观损伤机理的有限元分析方法.结合实例预报了碳/环氧四向编织复合材料本构的非线性行为,并与实验结果进行了对比.
Saturn＇s Rings Reveal Unexpected Phenomena
Institute of Scientific and Technical Information of China (English)
李颖
2004-01-01
Safely in orbit around Saturn, NASA's Cassini spacecraft sent back its first close-up images of the massive planet's rings on July 1, revealing an unexpectedly varied terrain featuring surprisingly sharp edges, braids and delicate ridges.
Splitting rivers at their seams: bifurcations and avulsion
Kleinhans, M.G.; Ferguson, R.I.; Lane, S.N.; Hardy, R.J.
2012-01-01
River bifurcations are critical but poorly understood elements of many geomorphological systems. They are integralelements of alluvial fans, braided rivers, fluvial lowland plains, and deltas and control the partitioning of water and sediment throughthese systems. Bifurcations are commonly unstable
Resilient thermal barrier for high temperatures
Frye, J. A.
1977-01-01
Abrasion-resistant thermal barrier, consisting of two layers of woven fabric or braided sleeving with bulk insulation sandwiched between, shows excellent resilience even after compression at temperatures above 980C.
Parity lifetime of bound states in a proximitized semiconductor nanowire
DEFF Research Database (Denmark)
Higginbotham, Andrew Patrick; Albrecht, Sven Marian; Kirsanskas, Gediminas;
2015-01-01
Quasiparticle excitations can compromise the performance of superconducting devices, causing high frequency dissipation, decoherence in Josephson qubits, and braiding errors in proposed Majorana-based topological quantum computers. Quasiparticle dynamics have been studied in detail in metallic...
Topology Explains Why Automobile Sunshades Fold Oddly
Feist, Curtis; Naimi, Ramin
2009-01-01
Automobile sunshades always fold into an "odd" number of loops. The explanation why involves elementary topology (braid theory and linking number, both explained in detail here with definitions and examples), and an elementary fact from algebra about symmetric group.
Public Key Protocol Based on Amalgamated Free Product
Upadhyay, Sumit Kumar; Kumar, Shiv Datt; Lal, Ramji
2011-01-01
In the spirit of Diffie Hellman the concept of a protocol algebra is introduced using certain amalgamated free product of Braid group B and Thompson group T together with a nilpotent subgroup H of index 2.
Andruskiewitsch, Nicolás; Yamane, Hiroyuki
2010-01-01
We discuss the relationship between Hopf superalgebras and Hopf algebras. We list the braided vector spaces of diagonal type with generalized root system of super type and give the defining relations of the corresponding Nichols algebras.
Restoration of natural capital: a key strategy on the path to sustainability
Blignaut, J.N.; Aronson, J.; Groot, de R.S.
2014-01-01
Three intertwining braids or strategies to enable transition towards sustainability can be identified, namely: (i) appropriate sustainable technologies, (ii) revising behaviour including reproduction and consumption patterns, and (iii) investment in the restoration of natural capital (RNC). Less exp
An $S_3$-symmetry of the Jacobi Identity for Intertwining Operator Algebras
Chen, Ling
2015-01-01
We prove an $S_{3}$-symmetry of the Jacobi identity for intertwining operator algebras. Since this Jacobi identity involves the braiding and fusing isomorphisms satisfying the genus-zero Moore-Seiberg equations, our proof uses not only the basic properties of intertwining operators, but also the properties of braiding and fusing isomorphisms and the genus-zero Moore-Seiberg equations. Our proof depends heavily on the theory of multivalued analytic functions of several variables, especially th...
Wilson operator algebras and ground states for coupled BF theories
Tiwari, Apoorv; Chen, Xiao; Ryu, Shinsei
2016-01-01
The multi-flavor $BF$ theories in (3+1) dimensions with cubic or quartic coupling are the simplest topological quantum field theories that can describe fractional braiding statistics between loop-like topological excitations (three-loop or four-loop braiding statistics). In this paper, by canonically quantizing these theories, we study the algebra of Wilson loop and Wilson surface operators, and multiplets of ground states on three torus. In particular, by quantizing these coupled $BF$ theori...
Li, Zhi Wei; Yu, Guo An; Brierley, Gary; Wang, Zhao Yin
2016-07-01
The influence of vegetation upon bedload transport and channel morphodynamics is examined along a channel stability gradient ranging from meandering to anabranching to anabranching-braided to fully braided planform conditions along trunk and tributary reaches of the Upper Yellow River in western China. Although the regional geology and climate are relatively consistent across the study area, there is a distinct gradient in the presence and abundance of riparian vegetation for these reaches atop the Qinghai-Tibet Plateau (elevations in the study area range from 2800 to 3400 m a.s.l.). To date, the influence of vegetative impacts upon channel planform and bedload transport capacity of alluvial reaches of the Upper Yellow River remains unclear because of a lack of hydrological and field data. In this region, the types and pattern of riparian vegetation vary with planform type as follows: trees exert the strongest influence in the anabranching reach, the meandering reach flows through meadow vegetation, the anabranching-braided reach has a grass, herb, and sparse shrub cover, and the braided reach has no riparian vegetation. A non-linear relation between vegetative cover on the valley floor and bedload transport capacity is evident, wherein bedload transport capacity is the highest for the anabranching reach, roughly followed by the anabranching-braided, braided, and meandering reaches. The relationship between the bedload transport capacity of a reach and sediment supply from upstream exerts a significant influence upon channel stability. Bedload transport capacity during the flood season (June-September) in the braided reach is much less than the rate of sediment supply, inducing bed aggradation and dynamic channel adjustments. Rates of channel adjustment are less pronounced for the anabranching-braided and anabranching reaches, while the meandering reach is relatively stable (i.e., this is a passive meandering reach).
Conley: Computing connection matrices in Maple
Barakat, Mohamed; Robertz, Daniel
2007-01-01
In this work we announce the Maple package conley to compute connection and C-connection matrices. conley is based on our abstract homological algebra package homalg. We emphasize that the notion of braids is irrelevant for the definition and for the computation of such matrices. We introduce the notion of triangles that suffices to state the definition of (C)-connection matrices. The notion of octahedra, which is equivalent to that of braids is also introduced.
Intramuscular Contact Lead Filled With Conductive Solution
Bamford, Robert M.; Hendrickson, James A.
1991-01-01
Proposed sheath for braided-wire intramuscular conductor preserves electrical continuity even if wire breaks. Plastic sheath surrounds conductive solution in which braided wire immersed. At end of cable, wire and sheath crimped together and press-fit in porous titanium electrode. Implanted surgically with aid of device resembling catheter. Used to deliver electrical stimuli to muscles in biomedical research on human and animal physiology, development of prostheses, regeneration of nerves and muscles, and artificial implants.
An $S_3$-symmetry of the Jacobi Identity for Intertwining Operator Algebras
Chen, Ling
2015-01-01
We prove an $S_{3}$-symmetry of the Jacobi identity for intertwining operator algebras. Since this Jacobi identity involves the braiding and fusing isomorphisms satisfying the genus-zero Moore-Seiberg equations, our proof uses not only the basic properties of intertwining operators, but also the properties of braiding and fusing isomorphisms and the genus-zero Moore Seiberg equations. Our proof depends heavily on the theory of multivalued analytic functions of several variables, especially the theory of analytic extensions.
Topological quantum computing with only one mobile quasiparticle.
Simon, S H; Bonesteel, N E; Freedman, M H; Petrovic, N; Hormozi, L
2006-02-24
In a topological quantum computer, universal quantum computation is performed by dragging quasiparticle excitations of certain two dimensional systems around each other to form braids of their world lines in 2 + 1 dimensional space-time. In this Letter we show that any such quantum computation that can be done by braiding n identical quasiparticles can also be done by moving a single quasiparticle around n - 1 other identical quasiparticles whose positions remain fixed.
Institute of Scientific and Technical Information of China (English)
Wei Du; Zaixing Jiang; Ying Zhang; Jie Xu
2013-01-01
The Lower Permian Shanxi（山西） Formation is one of the main gas-bearing stratigraphic units in northeastern Ordos（鄂尔多斯） Basin,China.Based on an integrated investigation of well logs,cores,and outcrop,we delineated the sedimentary facies of the lower member of the Shanxi Formation and divided the succession into three third-order sequences from base to top as SQ1,SQ2,and SQ3.The lower region of Shanxi Formation was deposited in the following sedimentary facies or subfacies: subaqueous braided channel,subaqueous interdistributary,mouth bar,swamp and shelf in the Daniudi（大牛地）Gas Field and braided channel,and shelf and lake at Heidaigou（黑岱沟)outcrop.Braided-river deposits form the lowstand systems tract (LST) in each sequence.Braided channels mark the sequence boundaries at Heidaigou outcrop.A shelf and lake depositional environment with dark gray mudstone forms the transgressive systems tract (TST).The location where dark gray mudstone first appears above the braided channel marks the first flooding surface (FFS),and the end of that marks the maximum flooding surface (MFS).The highstand systems tract (HST) deposits are fine-grained sediments with an aggradational parasequence at Heidaigou outcrop and swamp coalbed in the Daniudi Gas Field.Mouth-bar sand bodies in braided delta front,which form the LST in each sequence,form excellent reservoirs in the Daniudi Gas Field.
Torque-induced buckling behavior in stretched intertwined DNAs
Brahmachari, Sumitabha; Marko, John F.
Two intertwined DNA molecules (a DNA 'braid') is a common occurrence in the cell and is a relevant substrate for the study of topoisomerase and recombination enzymes. Single molecule experiments have observed the signature of a buckling transition in braids under tensile and torsional stress. We present a free energy model for braided DNA to investigate the mechanical properties of these structures. Our model is based on the semi-flexible polymer model for double helix DNA and is in quantitative accord with the experiments. We identify coexistence of a force-extended state with a plectonemically buckled state, which is reminiscent of single supercoiled DNA behavior. However, the absence of an intrinsic twist modulus in braided DNA results in unique mechanical properties such as non-linear torque in the extended state. At the buckling transition, we predict a jump in the braid extension due to the plectoneme end loop which acts as a nucleation barrier. We investigate the effect of salt concentration on the mechanical response of braids, e.g. we find that buckling starts at a lower linking number for lower salt concentration, the opposite of what is seen for single supercoiled DNAs. Also, concentrations less than 20 mM monovalent salt favor formation of multiple plectoneme domains. NSF Grant: DMR-9734178.
Some Aspects of Mathematical and Physical Approaches for Topological Quantum Computation
Directory of Open Access Journals (Sweden)
V. Kantser
2011-10-01
Full Text Available A paradigm to build a quantum computer, based on topological invariants is highlighted. The identities in the ensemble of knots, links and braids originally discovered in relation to topological quantum field theory are shown: how they define Artin braid group -- the mathematical basis of topological quantum computation (TQC. Vector spaces of TQC correspond to associated strings of particle interactions, and TQC operates its calculations on braided strings of special physical quasiparticles -- anyons -- with non-Abelian statistics. The physical platform of TQC is to use the topological quantum numbers of such small groups of anyons as qubits and to perform operations on these qubits by exchanging the anyons, both within the groups that form the qubits and, for multi-qubit gates, between groups. By braiding two or more anyons, they acquire up a topological phase or Berry phase similar to that found in the Aharonov-Bohm effect. Topological matter such as fractional quantum Hall systems and novel discovered topological insulators open the way to form system of anyons -- Majorana fermions -- with the unique property of encoding and processing quantum information in a naturally fault-tolerant way. In the topological insulators, due to its fundamental attribute of topological surface state occurrence of the bound, Majorana fermions are generated at its heterocontact with superconductors. One of the key operations of TQC -- braiding of non-Abelian anyons: it is illustrated how it can be implemented in one-dimensional topological isolator wire networks.
Integrating Data-Mining Support into a Brain-Image Database Using Open-Source Components
International Nuclear Information System (INIS)
Purpose: Previously, we described our implementation of a brain-image database (braid), based on the proprietary object-relational database-management system (ORDBMS). In conjunction with our collaborators, we have used this database to manage and analyze image and clinical data from what we call image-based clinical trials (IBCTs). Herein we describe the results of redesigning braid using open-source components, and integrating support for mining image and clinical data from braids user interface. Material and Methods: We re-designed and re-implemented BRAID using open-source components, including PostgreSQL, gcc, and PHP. We integrated data-mining algorithms into braid, based on PL/R, a PostgreSQL package to support efficient communication between R and PostgreSQL. Results: We present a sample clinical study to demonstrate how clinicians can perform queries for visualization, statistical analysis, and data mining, using a web-based interface. Conclusion: We have developed a database system with data-mining capabilities for managing, querying, analyzing and visualizing brain-MR images. We implemented this system using open-source components, with the express goal of wide dissemination throughout the neuroimaging research community. (authors)
Quantum computing with parafermions
Hutter, Adrian; Loss, Daniel
2016-03-01
Zd parafermions are exotic non-Abelian quasiparticles generalizing Majorana fermions, which correspond to the case d =2 . In contrast to Majorana fermions, braiding of parafermions with d >2 allows one to perform an entangling gate. This has spurred interest in parafermions, and a variety of condensed matter systems have been proposed as potential hosts for them. In this work, we study the computational power of braiding parafermions more systematically. We make no assumptions on the underlying physical model but derive all our results from the algebraical relations that define parafermions. We find a family of 2 d representations of the braid group that are compatible with these relations. The braiding operators derived this way reproduce those derived previously from physical grounds as special cases. We show that if a d -level qudit is encoded in the fusion space of four parafermions, braiding of these four parafermions allows one to generate the entire single-qudit Clifford group (up to phases), for any d . If d is odd, then we show that in fact the entire many-qudit Clifford group can be generated.
The near centre of Doi-Hopf module category _AM (H)~C
Institute of Scientific and Technical Information of China (English)
阚海斌; 许永华
1999-01-01
It is known that any strict tensor category （ C, （?）, I） determines a braided tensor category Z（C）, the centre of C. When A is a finite dimension Hopf algebra, Drinfel’d has proved that Z（AM） is equivalent to (（D（A））M as a braided tensor category, where AM is the left A-module category and D （A） is the Drinfel’d double of A. For a braided tensor category C, the braid CU, V is a natural isomorphism for any pair of object （U, V） in C. If weakening the natural isomorphism of the braid CU, V to a natural transformation, then CU, V is a prebraid and the category C with a prebraid is called a prebraided tensor category. Similarly it can be proved that any strict tensor category C determines a prebraided tensor category Z’ （C）, the near centre of C. An interesting prebraided tensor structure of the Yetter-Drinfel’d category C#AYDC#A is given, where C # A is the smash product bialgebra of C and A. And it is proved that the near centre of Doi-Hopf module AM（H）C is equivalent to the Yetter-Dri
Design of barrier coatings on kink-resistant peripheral nerve conduits.
Clements, Basak Acan; Bushman, Jared; Murthy, N Sanjeeva; Ezra, Mindy; Pastore, Christopher M; Kohn, Joachim
2016-01-01
Here, we report on the design of braided peripheral nerve conduits with barrier coatings. Braiding of extruded polymer fibers generates nerve conduits with excellent mechanical properties, high flexibility, and significant kink-resistance. However, braiding also results in variable levels of porosity in the conduit wall, which can lead to the infiltration of fibrous tissue into the interior of the conduit. This problem can be controlled by the application of secondary barrier coatings. Using a critical size defect in a rat sciatic nerve model, the importance of controlling the porosity of the nerve conduit walls was explored. Braided conduits without barrier coatings allowed cellular infiltration that limited nerve recovery. Several types of secondary barrier coatings were tested in animal studies, including (1) electrospinning a layer of polymer fibers onto the surface of the conduit and (2) coating the conduit with a cross-linked hyaluronic acid-based hydrogel. Sixteen weeks after implantation, hyaluronic acid-coated conduits had higher axonal density, displayed higher muscle weight, and better electrophysiological signal recovery than uncoated conduits or conduits having an electrospun layer of polymer fibers. This study indicates that braiding is a promising method of fabrication to improve the mechanical properties of peripheral nerve conduits and demonstrates the need to control the porosity of the conduit wall to optimize functional nerve recovery.
Wilson operator algebras and ground states for coupled BF theories
Tiwari, Apoorv; Ryu, Shinsei
2016-01-01
The multi-flavor $BF$ theories in (3+1) dimensions with cubic or quartic coupling are the simplest topological quantum field theories that can describe fractional braiding statistics between loop-like topological excitations (three-loop or four-loop braiding statistics). In this paper, by canonically quantizing these theories, we study the algebra of Wilson loop and Wilson surface operators, and multiplets of ground states on three torus. In particular, by quantizing these coupled $BF$ theories on the three-torus, we explicitly calculate the $\\mathcal{S}$- and $\\mathcal{T}$-matrices, which encode fractional braiding statistics and topological spin of loop-like excitations, respectively. In the coupled $BF$ theories with cubic and quartic coupling, the Hopf link and Borromean ring of loop excitations, together with point-like excitations, form composite particles.
Yetter-Drinfeld modules for Hom-bialgebras
Energy Technology Data Exchange (ETDEWEB)
Makhlouf, Abdenacer, E-mail: Abdenacer.Makhlouf@uha.fr [Université de Haute Alsace, Laboratoire de Mathématiques, Informatique et Applications, 4, rue des frères Lumière, F-68093 Mulhouse (France); Panaite, Florin, E-mail: Florin.Panaite@imar.ro [Institute of Mathematics of the Romanian Academy, PO-Box 1-764, RO-014700 Bucharest (Romania)
2014-01-15
The aim of this paper is to define and study Yetter-Drinfeld modules over Hom-bialgebras, a generalized version of bialgebras obtained by modifying the algebra and coalgebra structures by a homomorphism. Yetter-Drinfeld modules over a Hom-bialgebra with bijective structure map provide solutions of the Hom-Yang-Baxter equation. The category H/HYD of Yetter-Drinfeld modules with bijective structure maps over a Hom-bialgebra H with bijective structure map can be organized, in two different ways, as a quasi-braided pre-tensor category. If H is quasitriangular (respectively, coquasitriangular) the first (respectively, second) quasi-braided pre-tensor category H/HYD contains, as a quasi-braided pre-tensor subcategory, the category of modules (respectively, comodules) with bijective structure maps over H.
Anyonic statistics and large horizon diffeomorphisms for loop quantum gravity black holes
Pithis, Andreas G. A.; Ruiz Euler, Hans-Christian
2015-03-01
We investigate the role played by large diffeomorphisms of quantum isolated horizons for the statistics of loop quantum gravity (LQG) black holes by means of their relation to the braid group. To this aim the symmetries of Chern-Simons theory are recapitulated with particular regard to the aforementioned type of diffeomorphisms. For the punctured spherical horizon, these are elements of the mapping class group of S2, which is almost isomorphic to a corresponding braid group on this particular manifold. The mutual exchange of quantum entities in two dimensions is achieved by the braid group, rendering the statistics anyonic. With this we argue that the quantum isolated horizon model of LQG based on S U (2 )k-Chern-Simons theory exhibits non-Abelian anyonic statistics. In this way a connection to the theory behind the fractional quantum Hall effect and that of topological quantum computation is established, where non-Abelian anyons play a significant role.
Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine
Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)
1999-01-01
A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.
DNA as Topological Quantum Computer
Pitkänen, Matti
2010-01-01
This article represents a vision about how DNA might act as a topological quantum computer (tqc). Tqc means that the braidings of braid strands define tqc programs and M-matrix (generalization of S-matrix in zero energy ontology) defining the entanglement between states assignable to the end points of strands define the tqc usually coded as unitary time evolution for Schödinger equation. One can ends up to the model in the following manner. a) Darwinian selection for which the standa...
Seamless tube shape is constrained by endocytosis-dependent regulation of active Moesin
Schottenfeld-Roames, Jodi; Rosa, Jeffrey B.; Ghabrial, Amin S.
2014-01-01
Most tubes have “seams” – intercellular or autocellular junctions that seal membranes together into a tube – but “seamless” tubes also exist [1-3]. In Drosophila, stellate-shaped tracheal terminal cells make seamless tubes, with single branches running through each of dozens of cellular extensions. We find that mutations in braided impair terminal cell branching and cause formation of seamless tube cysts. We show that braided encodes Syntaxin7, and that cysts also form in cells deficient for ...
International Nuclear Information System (INIS)
In the fluvial-fan model of Proterozoic placers in South Africa, mid-fan and fanbase environments are illustrated by the Ventersdorp Contact Reef, proximal braided-belt environments by the B Reef, distal braided-belt environments by the Vaal Reef, and deltaiclike environments by sheets, ribbons, and pods at the extremities of the South and Basal Reefs. The nature of distribution of gold and uranium in these various environments has been evaluated and the knowledge successfully applied by the author to the valuation and practical mining of the reefs since 1965
Wilson loop invariants from WN conformal blocks
Alekseev, Oleg; Novaes, Fábio
2015-12-01
Knot and link polynomials are topological invariants calculated from the expectation value of loop operators in topological field theories. In 3D Chern-Simons theory, these invariants can be found from crossing and braiding matrices of four-point conformal blocks of the boundary 2D CFT. We calculate crossing and braiding matrices for WN conformal blocks with one component in the fundamental representation and another component in a rectangular representation of SU (N), which can be used to obtain HOMFLY knot and link invariants for these cases. We also discuss how our approach can be generalized to invariants in higher-representations of WN algebra.
One Kind of Routing Algorithm Modified in Wireless Sensor Network
Directory of Open Access Journals (Sweden)
Wei Ni Ni
2016-01-01
Full Text Available The wireless sensor networks are the emerging next generation sensor networks, Routing technology is the wireless sensor network communication layer of the core technology. To build reliable paths in wireless sensor networks, we can consider two ways: providing multiple paths utilizing the redundancy to assure the communication reliability or constructing transmission reliability mechanism to assure the reliability of every hop. Braid multipath algorithm and ReInforM routing algorithm are the realizations of these two mechanisms. After the analysis of these two algorithms, this paper proposes a ReInforM routing algorithm based braid multipath routing algorithm.
Coherence in monoidal track categories
Guiraud, Yves
2010-01-01
We introduce homotopical methods based on rewriting on higher-dimensional categories to prove coherence results in categories with an algebraic structure. We express the coherence problem for (symmetric) monoidal categories as an asphericity problem for a track category and use rewriting methods on polygraphs to solve it. The setting is generalized to more general coherence problems, seen as 3-dimensional word problems in a track category. We prove general results that, in the case of braided monoidal categories, yield the coherence theorem for braided monoidal categories.
On fundamental groups related to the Hirzebruch surface F1
Institute of Scientific and Technical Information of China (English)
Michael; FRIEDMAN; Mina; TEICHER
2008-01-01
Given a projective surface and a generic projection to the plane,the braid monodromy factorization（and thus,the braid monodromy type）of the complement of its branch curve is one of the most important topological invariants,stable on deformations.From this factorization,one can compute the fundamental group of the complement of the branch curve,either in C2 or in CP2.In this article,we show that these groups,for the Hirzebruch surface F1,（a,b）,are almost-solvable.That is, they are an extension of a solvable group,which strengthen the conjecture on degeneratable surfaces.
On fundamental groups related to the Hirzebruch surface F1
Institute of Scientific and Technical Information of China (English)
Michael FRIEDMAN; Mina TEICHER
2008-01-01
Given a.projective surface and a generic projection to the plane,the braid monodromy factorization (and thus,the braid monodromy type) of the complement of its branch curve is one of the most important topological invariants,stable on deformations.From this factorization,one can compute the fundamental group of the complement of the branch curve,either in C2 or in CP2.In this article,we show that these groups,for the Hirzebruch surface F1,(a,b),are almost-solvable.That is,they are an extension of a solvable group,which strengthen the conjecture on degeneratable surfaces.
New Public Key Cryptosystems from Combinatorial Group Theory
Institute of Scientific and Technical Information of China (English)
TANG Xueming; WANG Xiaofei; HONG Fan; CUI Guohua
2006-01-01
External direct product of some low layer groups such as braid groups and general Artin groups, with a kind of special group action on it, provides a secure cryptographic computation platform, which can keep secure in the quantum computing epoch. Three hard problems on this new platform, Subgroup Root Problem, Multi-variant Subgroup Root Problem and Subgroup Action Problem are presented and well analyzed, which all have no relations with conjugacy. New secure public key encryption system and key agreement protocol are designed based on these hard problems. The new cryptosystems can be implemented in a general group environment other than in braid or Artin groups.
Twisting Functors for Quantum Group Modules
DEFF Research Database (Denmark)
Pedersen, Dennis Hasselstrøm
We construct twisting functors for quantum group modules. First over the field Q(v) but later over any Z[v,v^{−1}]-algebra. The main results in this paper are a rigerous definition of these functors, a proof that they satisfy braid relations and applications to Verma modules.......We construct twisting functors for quantum group modules. First over the field Q(v) but later over any Z[v,v^{−1}]-algebra. The main results in this paper are a rigerous definition of these functors, a proof that they satisfy braid relations and applications to Verma modules....
Wilson loop invariants from WN conformal blocks
Directory of Open Access Journals (Sweden)
Oleg Alekseev
2015-12-01
Full Text Available Knot and link polynomials are topological invariants calculated from the expectation value of loop operators in topological field theories. In 3D Chern–Simons theory, these invariants can be found from crossing and braiding matrices of four-point conformal blocks of the boundary 2D CFT. We calculate crossing and braiding matrices for WN conformal blocks with one component in the fundamental representation and another component in a rectangular representation of SU(N, which can be used to obtain HOMFLY knot and link invariants for these cases. We also discuss how our approach can be generalized to invariants in higher-representations of WN algebra.
Simulation of non-Abelian anyons using ribbon operators connected to a common base site
Energy Technology Data Exchange (ETDEWEB)
Luo Xiwang; Han Yongjian; Guo Guangcan; Zhou Xingxiang; Zhou Zhengwei [Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026 (China)
2011-11-15
A convenient and effective way in the quantum double model to study anyons in a topological space with a tensor product structure is to create and braid anyons using ribbon operators connected to a common base site [A. Kitaev, Ann. Phys. (NY) 303, 2 (2003)]. We show how this scheme can be simulated in a physical system by constructing long ribbon operators connected to a base site that is placed far away. We describe how to move and braid anyons using these ribbon operators, and how to perform measurement on them. We also give the smallest scale of a system that is sufficient for proof-of-principle demonstration of our scheme.
Enveloping algebras of some quantum Lie algebras
Pourkia, Arash
2014-01-01
We define a family of Hopf algebra objects, $H$, in the braided category of $\\mathbb{Z}_n$-modules (known as anyonic vector spaces), for which the property $\\psi^2_{H\\otimes H}=id_{H\\otimes H}$ holds. We will show that these anyonic Hopf algebras are, in fact, the enveloping (Hopf) algebras of particular quantum Lie algebras, also with the property $\\psi^2=id$. Then we compute the braided periodic Hopf cyclic cohomology of these Hopf algebras. For that, we will show the following fact: analog...
Uranium mineralization in fluviatile facies
International Nuclear Information System (INIS)
Over half the world's known uranium reserves occur in fluviatile rocks. These deposits include Archean quartz-pebble conglomerates of alluvial fan facies and arkosic braided and meandering fluviatile sandstone facies. Uranium-bearing quartz-pebble conglomerates are described. Approximately 40% of the world's uranium reserves have been found in epigenetic sandstone deposits. Deposits of uranium in braided or meandering fluviatile sandstones can be grouped into peneconcordant and roll-front types. Uranium deposits are widely distributed through central, northern and western Australia but only a very small proportion of the reserves occur in fluviatile sequences
Development and evaluation of polybenzoxazole fibrous structures
Orndoff, Evelyne
1995-01-01
Woven and braided polybenzoxazole (PBO) structures have been developed for aerospace applications. The properties of PBO fibers are compared to those of other high performance fibers. PBO is unique for combining excellent flammability properties with the highest tensile strength and modulus of all synthetic organic fibers. The PBO structures are specifically developed to be compared to similar Kevlar structures. The physical, mechanical, thermal, and oxidative properties of the PBO woven and braided structures are determined. The resistance to various chemicals and to UV light is evaluated. Recommendations for specific aerospace applications are given with comments for further development and industrial applications.
Clifford Hopf-gebra and Bi-universal Hopf-gebra
Oziewicz, Z
1997-01-01
We consider a pair of independent scalar products, one scalar product on vectors, and another independent scalar product on dual space of co-vectors. The Clifford co-product of multivectors is calculated from the dual Clifford algebra. With respect to this co-product unit is not group-like and vectors are not primitive. The Clifford product and the Clifford co-product fits to the bi-gebra with respect to the family of the (pre)-braids. The Clifford bi-gebra is in a braided category iff at least one of these scalar products vanish.
A Partition Temperley-Lieb Algebra
Juyumaya, Jesús
2013-01-01
We introduce a generalization of the Temperley--Lieb algebra. This generalization is defined by adding certain relations to the algebra of braids and ties. A specialization of this last algebra corresponds to one small Ramified Partition algebra, this fact is the motivation for the name of our generalization.
Twisting theory for weak Hopf algebras
Institute of Scientific and Technical Information of China (English)
CHEN Ju-zhen; ZHANG Yan; WANG Shuan-hong
2008-01-01
The main aim of this paper is to study the twisting theory of weak Hopf algebras and give an equivalence between the (braided) monoidal categories of weak Hopf bimodules over the original and the twisted weak Hopf algebra to generalize the result from Oeckl (2000).
Seamless tube shape is constrained by endocytosis-dependent regulation of active Moesin.
Schottenfeld-Roames, Jodi; Rosa, Jeffrey B; Ghabrial, Amin S
2014-08-01
Most tubes have seams (intercellular or autocellular junctions that seal membranes together into a tube), but "seamless" tubes also exist. In Drosophila, stellate-shaped tracheal terminal cells make seamless tubes, with single branches running through each of dozens of cellular extensions. We find that mutations in braided impair terminal cell branching and cause formation of seamless tube cysts. We show that braided encodes Syntaxin7 and that cysts also form in cells deficient for other genes required either for membrane scission (shibire) or for early endosome formation (Rab5, Vps45, and Rabenosyn-5). These data define a requirement for early endocytosis in shaping seamless tube lumens. Importantly, apical proteins Crumbs and phospho-Moesin accumulate to aberrantly high levels in braided terminal cells. Overexpression of either Crumbs or phosphomimetic Moesin induced lumenal cysts and decreased terminal branching. Conversely, the braided seamless tube cyst phenotype was suppressed by mutations in crumbs or Moesin. Indeed, mutations in Moesin dominantly suppressed seamless tube cyst formation and restored terminal branching. We propose that early endocytosis maintains normal steady-state levels of Crumbs, which recruits apical phosphorylated (active) Moe, which in turn regulates seamless tube shape through modulation of cortical actin filaments. PMID:25065756
Splitting rivers at their seams: bifurcations and avulsion
Kleinhans, M.G.; Ferguson, R.I.; Lane, S.N.; Hardy, R.J.
2012-01-01
River bifurcations are critical but poorly understood elements of many geomorphological systems. They are integral elements of alluvial fans, braided rivers, fluvial lowland plains, and deltas and control the partitioning of water and sediment through these systems. Bifurcations are commonly unstabl
$W_4$ Toda example as hidden Liouville CFT
Furlan, P
2016-01-01
We construct correlators in the $W_4$ Toda 2d conformal field theory for a particular class of representations and demonstrate a relation to a $W_2$ (Virasoro) theory with different central charge. The relevance of the classical limits of the constructed 3-point functions and braiding matrices to problems in 4d conformal theories is discussed.
Experimental meandering river with chute cutoffs
Dijk, W.M. van; Lageweg, W.I. van de; Kleinhans, M.G.
2012-01-01
Braided rivers are relatively simple to produce in the laboratory, whereas dynamic meandering rivers have not been sustained beyond initial bend formation. Meandering is theoretically explained by bend instability growing from planimetric perturbation, which convects downstream. In this study, we ex
Language Correlates of Disciplinary Literacy
Fang, Zhihui
2012-01-01
Disciplinary literacy is defined here as the ability to engage in social, semiotic, and cognitive practices consistent with those of content experts. Characterizing literacy development as a process of braiding 3 language strands of everyday language, abstract language, and metaphoric language, this article describes the lexical and grammatical…
Georgiev, L S
2006-01-01
We review the topological quantum computation scheme of Das Sarma et al. from the perspective of the conformal field theory for the two-dimensional critical Ising model. This scheme originally used the monodromy properties of the non-Abelian excitations in the Pfaffian quantum Hall state to construct elementary qubits and execute logical NOT on them. We extend the scheme of Das Sarma et al. by exploiting the explicit braiding transformations for the Pfaffian wave functions containing 4 and 6 quasiholes to implement, for the first time in this context, the single-qubit Hadamard and phase gates and the two-qubit Controlled-NOT gate over Pfaffian qubits in a topologically protected way. In more detail, we explicitly construct the unitary representations of the braid groups B_4, B_6 and B_8 and use the elementary braid matrices to implement one-, two- and three-qubit gates. We also propose to construct a topologically protected Toffoli gate, in terms of a braid-group based Controlled-Controlled-Z gate precursor. ...
The homological content of the Jones representations at $q = -1$
DEFF Research Database (Denmark)
Egsgaard, Jens Kristian; Fuglede Jørgensen, Søren
We generalize a discovery of Kasahara and show that the Jones representations of braid groups, when evaluated at $q = -1$, are related to the action on homology of a branched double cover of the underlying punctured disk. As an application, we prove for a large family of pseudo-Anosov mapping...
Mapping spaces and automorphism groups of toric noncommutative spaces
Barnes, Gwendolyn E; Szabo, Richard J
2016-01-01
We develop a sheaf theory approach to toric noncommutative geometry which allows us to formalize the concept of mapping spaces between two toric noncommutative spaces. As an application we study the `internalized' automorphism group of a toric noncommutative space and show that its Lie algebra has an elementary description in terms of braided derivations.
Fibre distribution inside yarns of textile composite: gemetrical and FE modelling
Koissin, V.; Ivanov, D.S.; Lomov, S.V.; Verpoest, I.
2006-01-01
This article addresses the experimental investigation and modelling of the uneven fibre distribution inside yarns of a textile composite. The test data is given for the tri-axial carbon-fibre braid; a considerable irregularity is revealed for the fibre distribution along and across the yarns. The im
Weak Galois and Weak Cocleft Coextensions
Institute of Scientific and Technical Information of China (English)
J.N. Alonso (A)lvarez; J.M. Fernández Vilaboa; R. González Rodríguez; A.B. Rodríguez Raposo
2007-01-01
For a weak entwining structure (A, C,ψ) living in a braided monoidal category with equalizers and coequalizers, we formulate the notion of weak A-Galois coextension with normal basis and we show that these Galois coextensions are equivalent to the weak A-cocleft coextensions introduced by the authors.
Improved numerical modelling of morphodynamics of rivers with steep banks
The flow and sediment transport processes near steep streambanks, which are commonly found in meandering, braided, and anastomosing stream systems, exhibit complex patterns. The interactions between bed and bank morphologic adjustment, and their governing processes are still not well understood. Inc...
Processing investigation and optimization for hybrid thermoplastic composites
Institute of Scientific and Technical Information of China (English)
M Tufail
2007-01-01
A thermoplastic based composite material is suitable for automobile and aerospace applications. The recyclability of thermoplastic and clean processing further enhance its use. The only limitation encountered in using this material is its high-melt viscosity. Various techniques have been developed to overcome this problem. Commingled materials are one of such methods adopted for making proper use of thermoplastic. A major problem observed during the use of a commingled material is its de-commingling, wherein, the uniform distribution of fiber and thermoplastic yarn gets disturbed and affects the final quality of the composite. The effects of the braiding process on laminate quality were investigated. Flat plaques were produced by braiding the commingled yarn, using a 48-carrier braiding machine. The braids (and control woven samples) were subsequently heated and consolidated in a nonisothermal compression molding operation. Prior to the manufacture of the 'best quality' plaques, a series of moldings were produced under different consolidation conditions, to study the dependence of properties on the process variables. This enabled a processing window to be established for each material and helped to separate the respective effects of yarn handling, textile processing, and consolidation on laminate properties.
Iwasaki, Toshiki; Shimizu, Yasuyuki; Kimura, Ichiro
2016-07-01
Recent studies suggest that braided river could be single-thread channel by colonization of riparian vegetation; however, this kind of mutual interactions between physical and ecological processes in rivers are still poorly understood. Here we investigate the development of meandering channel in a river, which was originally braided and currently vegetated, the Otofuke River in Japan. The significant morphological processes of this river during a destructive flood event was studied using a two-dimensional morphodynamic model. Using well-calibrated parameters, this model qualitatively reproduced observed morphological changes such as the co-development of sand bars, bar-induced meandering and a chute cutoff. We find that for vegetated channels, meandering could maintain moderate sinuosity; in contrast, in the absence of riparian vegetation, bar-induced meandering channels could become braided. This suggests that distinct meandering channels could be a fundamental channel morphology in the originally braided, but currently vegetated river; however, the simultaneous occurrence of the chute cutoff and meandering indicates that this channel could not be a fully-developed high amplitude meandering channel.
Sharing the Arts of the Blue Ridge Mountains. Final Report, February 1977-January 1978.
Holman, Martha; Gailey, Lamar
Designed to utilize basic skills and develop a vocational or vocational skills, eight adult basic education modules were developed which highlight authentic Blue Ridge Mountain crafts. Modules provide instruction in apple dolls, braided rugs, candles, caning, corn shuck dolls, pottery, quilting, and weaving (see Note). Selection of the crafts was…
Excellent Ballistic Impact Properties Demonstrated By New Fabric
Pereira, J. Michael; Revilock, Duane M.; Hopkins, Dale A.
2002-01-01
Recently, a relatively new industrial fiber known by the trade name Zylon has been under commercial development by Toyobo Co., Ltd., Japan. In ballistic impact tests conducted at the NASA Glenn Research Center, it was found that dry fabric braided of Zylon had greater ballistic impact capacity than comparable (braid style and weight) fabric braided of Kevlar. To study the potential use of Zylon fabric in jet engine containment systems, the fabric was tested in Glenn's Structures and Acoustics Division Ballistic Impact Facility under conditions simulating those which occur in a jet engine blade-out event. Circular ring test specimens were fabricated by wrapping five layers of braided Zylon or Kevlar fabric around an inner ring made of a thin sheet of aluminum and a 1-in.-thick layer of aluminum honeycomb. The test specimens had an inner diameter of 40 in., an axial length of 10 in., and a wall thickness of approximately 1.5in. A test specimen is shown in the photograph.
Jucys-Murphy elements for Birman-Murakami-Wenzl algebras
Isaev, A. P.; Ogievetsky, O. V.
2011-05-01
The Burman-Wenzl-Murakami algebra, considered as the quotient of the braid group algebra, possesses the commutative set of Jucys-Murphy elements. We show that the set of Jucys-Murphy elements is maximal commutative for the generic Birman-Wenzl-Murakami algebra and reconstruct the representation theory of the tower of Birman-Wenzl-Murakami algebras.
Endomorphism Algebras of Tensor Powers of Modules for Quantum Groups
DEFF Research Database (Denmark)
Andersen, Therese Søby
the group algebra of the braid group to the endomorphism algebra of any tensor power of the Weyl module with highest weight 2. We take a first step towards determining the kernel of this map by reformulating well-known results on the semisimplicity of the Birman-Murakami-Wenzl algebra in terms of the order...
A topological spin-statistics theorem or a use of the antiparticle
International Nuclear Information System (INIS)
A spin-statistics theorem for spinning particles in Rd is proved without using relativity or field theory, but assuming the existence of antiparticles. The theorem excludes nonabelian statistics such as parastatistics of order 2 and more for d≥3 and statistics based on nonabelian representations of the braid groups for d=2. (orig.)
Non-Abelian Chern-Simons Quantum Mechanics
Lee, Taejin; Oh, Phillial
1993-01-01
We propose a classical model for the non-Abelian Chern-Simons theory coupled to $N$ point-like sources and quantize the system using the BRST technique. The resulting quantum mechanics provides a unified framework for fractional spin, braid statistics and Knizhnik-Zamolodchikov equation.
Design and Analysis Methodologies for Inflated Beams
Veldman, S.L.
2005-01-01
The central theme of the thesis is bending behaviour of inflated beams. Three different types of beams have been analysed for the bending load case: a straight cylindrical beam made of anisotropic foil material, a conical beam made of an isotropic foil material, and a carbon fibre braided beam. The
da Cruz, Wellington
2002-01-01
We consider the {\\it fractal von Neumann entropy} associated with the {\\it fractal distribution function} and we obtain for some {\\it universal classes h of fractons} their entropies. We obtain also for each of these classes a {\\it fractal-deformed Heisenberg algebra}. This one takes into account the braid group structure of these objects which live in two-dimensional multiply connected space.
Digital Repository Service at National Institute of Oceanography (India)
Laluraj, C.M.; Gopinath, G.; DineshKumar, P.K.; Balachandran, K.K.
is controlled by the productivity of the overlying water column. The evolution of this island is believed to be due to fluvial inputs from Muvattupuzha River. The braid shape of the island is attributed to the high-energy flow along the wedge of the estuary...
Brownian motion on a smash line
Ellinas, D; Ellinas, Demosthenes; Tsohantjis, Ioannis
2000-01-01
Brownian motion on a smash line algebra (a smash or braided version of the algebra resulting by tensoring the real line and the generalized paragrassmann line algebras), is constructed by means of its Hopf algebraic structure. Further, statistical moments, non stationary generalizations and its diffusion limit are also studied. The ensuing diffusion equation posseses triangular matrix realizations.
A secure method of nasal endotracheal tube stabilization with suture and rubber tube.
Ota, Y; Karakida, K; Aoki, T; Yamazaki, H; Arai, I; Mori, Y; Nakatogawa, N; Suzuki, T
2001-12-01
A new method of stabilizing the nasal endotrascheal tube was described. The tube was secured to the anterior portion of the nasal septum with braided silk thread, which was tightened over the rubber tube to keep air route of the cuff open. There found no complications such as unplanned extubation, necrosis and infections of the nasal septum.
Directory of Open Access Journals (Sweden)
Ching-Wen Lou
2015-12-01
Full Text Available In order to solve the incompatibility between high porosity and mechanical properties, this study fabricates bone scaffolds by combining braids and sodium alginate (SA membranes. Polyethylene terephthalate (PET plied yarns are braided into hollow, porous three dimensional (3D PET braids, which are then immersed in SA solution, followed by cross-linking with calcium chloride (CaCl2 and drying, to form PET bone scaffolds. Next, SA membranes are rolled and then inserted into the braids to form the spiral and porous PET/SA bone scaffolds. Samples are finally evaluated for surface observation, porosity, water contact angle, compressive strength, and MTT assay. The test results show that the PET bone scaffolds and PET/SA bone scaffolds both have good hydrophilicity. An increasing number of layers and an increasing CaCl2 concentration cause the messy, loose surface structure to become neat and compact, which, in turn, decreases the porosity and increases the compressive strength. The MTT assay results show that the cell viability of differing SA membranes is beyond 100%, indicating that the PET/SA bone scaffolds containing SA membranes are biocompatible for cell attachment and proliferation.
Chen, Wen-Cheng; Ko, Chia-Ling; Yang, Jia-Kai; Wu, Hui-Yu; Lin, Jia-Horng
2016-03-01
An attempt to maintain the three-dimensional space into restorative sites through the conveniently pack porous fillers are general used strategy. Advancement in the manufacturing protective shells in the scaffolds, which would be filled with brittle ceramic grafts for the development of highly connective pores provides the approach to solve crack problem for generating the tissues. Therefore, multilayered braided and alkalized poly(lactic acid) (PLA) composites with calcium phosphate bone cement (CPC) were synthesized and compared. The PLA/CPC composites were divided into various groups according to a series of heat-treatment temperatures (100-190 °C) and periods (1-3 h) and then characterized. The effects of 24-h immersion on the strength decay resistance of the samples were compared. Results showed that the residual oil capped on the surfaces of alkalized PLA braid was removed, and the structure was unaltered. However, the reduced tensile stress of alkalized PLA braids was due to ester-group formation by hydrolysis. Mechanical test results of PLA/CPC composites showed that the strength significantly increased after heat treatment, except when the heating temperature was higher than the PLA melting point at approximately 160-170 °C. The degree of PLA after recrystallization became higher than that of unheated composites, thereby leading to reduced strength and toughness of the specimen. Braiding fibers of biodegradable PLA reinforced and toughened the structure particularly of the extra-brittle material of thin-sheet CPC after implantation.
Tree technique and irreducible tensor operators for SUq(2) quantum algebra, 9j-symbols
International Nuclear Information System (INIS)
The graphic technique of Kuznetsov-Smorodinov for the SUq(2) quantum algebra is discussed. The transformation of trees including the braiding of branches is considered. Using the universal R-matrix the q-analog of 9j-symbol is introduced and its symmetry are examined
Meandering rivers - feedbacks between channel dynamics, floodplain and vegetation
van Dijk, W.M.
2013-01-01
Rivers have distinctive channel patterns such as multi-channel braiding and single-channel meandering. Why these different river patterns emerge is only qualitatively understood. Yet, we have not been able to retain dynamic meandering in laboratory experiments. The main objective of this thesis was
Pressurizable structures comprising different surface sections
Koussios, S.; Bergsma, O.K.; Beukers, A.
2004-01-01
The invention relates to composite pressurizable structures which are overwound with fibres or are braided. The pressurizable structures comprise axial sections which in turn comprise both concave and convex surfaces. The shape characteristics are related to geodesic as well as non-geodesic trajecto
Berenbrock, Charles E.
2015-01-01
Reduction of cross-sectional data using a genetic algorithm method, and the effects of data reduction on channel geometry and steady-flow profiles, were analyzed. Two reduction methods─standard and genetic algorithms─were used to reduce cross-sectional data from the Kootenai River in northern Idaho. Cross sections that are representative of meander, straight, braided, and canyon reaches were used to evalutate the reduction methods. Visual and hydraulic analyses were used to assess the methods. The genetic algorithm-reduced cross sections approximated the shape of the original cross sections better than the standard-reduced cross sections. A greater number of cross-sectional data points were needed for reduced cross sections in the straight reach, and even more in the braided reach, because a greater amount of data points are needed to adequately define cross sections that have greater topographic varability. For the genetic algorithm-reduction method, about 40 data points were needed to adequately define the shape of a reduced cross section in the braided reach compared to 10 to 20 data points in the meander and canyon reaches. The standard-reduction method needed about 70 data points for the braided reach and more than 30 points for the meander and canyon reaches. The genetic algorithm can effectively reduce data while staying within the threshold set by the maximum number of points to be included in the reduced dataset.
A Tow-Level Progressive Damage for Simulating Carbon-Fiber Textile Composites: Interim Report
Energy Technology Data Exchange (ETDEWEB)
Zywicz, E.
2000-07-01
A numerical approach to model the elasto-plastic and tensile damage response of tri-axially braided carbon-fiber polymeric-matrix composites is developed. It is micromechanically based and consists of a simplified unit cell geometry, a plane-stress tow-level constitutive relationship, a one-dimensional undulation constitutive law, and a non-traditional shell element integration rule. The braided composite lamina is idealized as periodic in the plane, and a simplified three-layer representative volume (RV) is assembled from axial and braider tows and pure resin regions. The constituents in each layer are homogenized with an iso-strain assumption in the fiber-direction and an iso-stress condition in the other directions. In the upper and lower layers, the fiber-direction strain is additively decomposed into an undulation and a tow portion. A finite-deformation tow model predicts the plane-stress tow response and is coupled to the undulation constitutive relationship. The overall braid model is implemented in DYNA3D and works with traditional shell elements. The finite-deformation tow constitutive relationship is derived from the fiber elasticity and the isotropic elasto-plastic power-law hardening matrix response using a thermodynamic framework and simple homogenization assumptions. The model replicates tensile damage evolution, in a smeared sense, parallel and perpendicular to the fiber axis and is regularized to yield mesh independent results. The tow-level model demonstrates reasonable agreement, prior to damage, with detailed three-dimensional FE (finite element) elasto-plastic simulations of aligned, periodically arranged, uni-directional composites. The 3-layer braid model response is compared with predictions obtained from detailed micromechanical simulations of the braid's unit cell in uni-axial extension, shear, and flexure for three braid angles. The elastic properties show good agreement as does the non-linear response for loadings dominated by the
Zebdi, Oussama
High performance composites reinforced by woven or braided fabrics have several different applications in various fields such as in the aerospace, automobile and marine industry. This research project was carried out at the Ecole Polytechnique de Montreal in collaboration with an industrial sponsor, the company Composites Atlantic Ltd. Composite springs often represent an interesting alternative, given the reduction in weight that they allow with equal mechanical performance compared to metallic springs. Their good resistance to fatigue and corrosion bring additional benefits in several industrial applications. Moreover, the use of the composites increases safety by avoiding the risks of brutal rupture because of the low propagation velocity of cracks in this type of material. Lastly, in electrotechnics, another significant advantage comes into play because of the electrical insulation capability of composite springs. Few research results can be found on composite springs in the scientific literature. The first part of this thesis studies the problems connected with the design of composite springs. The results are promising, because it was confirmed that composite springs can be devised with the same mechanical performance in term of stiffness as metallic ones. Two solutions were found to replace the metallic springs of the suspension of a four wheel drive: the first spring was in carbon-epoxy, and the second one in glass-epoxy. In the second part, software was developed in order to devise a new approach to predict the mechanical properties of woven or braided composites. This work shows how an inverse method based on plate laminate theory allows creating, from experimental results on braided composites, a virtual basic ply that includes the effect of fiber architecture (undulation and braiding angle). Using this model, the properties of the composite can be predicted for any braid angle. The comparison with the experimental results shows a good correlation with
Cano, Roberto J.; Furrow, Keith W.
1993-01-01
Results are presented from an experimental evaluation of the combined effects of temperature and humidity cycling on AS4/3501-6 composites (unstitched, Kevlar 29 stitched, and S-2 glass stitched uniweave fabric) and AS4/E905L composites (2-D, S-2 glass stitched 2-D, and 3-D braided fabric). The AS4/3501-6 uniweave material had a quasi-isotropic layup, whereas the AS4/E905L materials were braided in a (+/-30 deg/0 deg)(sub s) orientation. Data presented include compression strengths and compression-compression fatigue results for uncycled composites and cycled composites (160, 480, 720, and 1280 cycles from 140 deg F at 95 percent relative humidity to -67 deg F). To observe the presence of microcracking within the laminates, photomicrographs were taken of each material type at the end of each cycling period. Microcracks were found to be more prevalent within stitched laminates, predominantly around individual stitches. The glass stitched laminates showed significant microcracking even before cycling. Less microcracking was evident in the Kevlar stitched materials, whereas the unstitched uniweave material developed microcracks only after cycling. The 3-D braid did not develop microcracks. The static compression strengths of the unstitched and Kevlar stitched uniweave materials were degraded by about 10 percent after 1280 temperature/humidity cycles, whereas the reduction in compression strength for the glass stitched uniweave was less than 3 percent. The reduction in compression strength for the glass stitched 2-D braid was less than 8 percent. The unstitched 2-D and 3-D braids did not lose strength from temperature/humidity cycling. The compression-compression fatigue properties of all six material types were not affected by temperature/humidity cycling.
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Detailed studies of petrology, palaeocurrent direction, palaeogeomorphology and palaeohydrodynamics have been conducted for the Permian-Triassic Cangfanggou Group in the foredeep of the Bogda Mountains in the southeastern Junggar Basin, Xinjiang. Sedimentary environments and facies of alluvial fans and pebbly braided rivers, sandy braided rivers, meandering rivers, low-sinuosity rivers, swamps and fresh-water lakes are recognized in the group. Climate and tectonics of source areas strongly controlled the evolution of the sedimentary environments and facies in the foredeep. The block faulting in the Bogda Mountains increased the ground slope, which led to a drastic increase in the grain size of the sediments.Humid climate, being beneficial to plant growth, would provide protection of channel banks and at the same time weaken chemical weathering in the source area,thus large amounts of clay materials are available for the formation of clay plugs. As a resuit, stable banks and meandering river belts are formed. Conversely, increasing aridity would strengthen mechanical weathering and reduce the mumber of clay plugs.Besides, plants would diminish gradually and channels would become more mobile. In this casc the decrease of transported clay materials would reduce the stability of the bank and result in a wider and shallower channel. Therefore, humid climate is beneficial to the formation of meandering rivers even if there is strong block faulting in the source areas and the ground slope is very large. As aridity further increases, plants would diminish and vanish at last,the meandering rivers prevalent under humid climate conditions would be transformed to low-sinuosity rivers even if the ground is gentle and the land is tectonically stable. And as the climate became more arid and the source area uplifted intensively to provide more sedimentary materials, low-sinuosity' rivers would be transformed to braided ones quickly, and wedge-like sedimentary bodies of the braided
DUAL TO TWISTING THEORY FOR WEAK HOPF ALGEBRAS%弱Hopf 代数的扭曲理论
Institute of Scientific and Technical Information of China (English)
陈菊珍; 宋新霞
2008-01-01
本文研究了弱Hopf代数的扭曲理论的对偶问题.利用了弱Hopf代数上的弱Hopf双模的(辫子)张量范畴与扭曲弱Hopf代数上的弱Hopf双模的(辫子)张量范畴等价方法,得到Long模范畴是Yetter-Drinfel'd模范畴的辫子张量子范畴.推广了Oeckl(2000)的结果.%In this paper we study the dual case of the twisting theory of weak Hopf algebras. Using the equivalent between the (braided) monoidal categories of weak Hopf bimodules over the original and the twisted weak Hopf algebras, we get the Long module category is a braided tensor subcategory of a Yetter-Drinfel'd module category, and then generalize the result of Oeckl (2000).
Candlestick oven with a silica wick provides an intense collimated cesium atomic beam
Pailloux, A.; Alpettaz, T.; Lizon, E.
2007-02-01
This article shows that readily available glass and silica fibers and braids are suitable capillary structure for recirculating ovens, such as candlestick ovens, becoming then an alternative wick material to conventional metal based capillary structures. In order to study wettability and capillarity of metallic liquid cesium on borosilicate and silica microstructures, samples were selected, prepared, and tested experimentally. The contact angle of cesium on silica glass was roughly measured: θ =35°±10°. A commercially available silica braid was then introduced inside a candlestick oven to transfer the metallic liquid cesium from the cold reservoir to the hot emission point of the candlestick. A collimated cesium atomic beam of intensity of 2×1016at./ssr was obtained, stable and reproducible. Furthermore, this modified oven is easy to handle daily.
Topological quantum gate construction by iterative pseudogroup hashing
Burrello, Michele; Mussardo, Giuseppe; Wan, Xin
2011-02-01
We describe the hashing technique for obtaining a fast approximation of a target quantum gate in the unitary group SU(2) represented by a product of the elements of a universal basis. The hashing exploits the structure of the icosahedral group (or other finite subgroups of SU(2)) and its pseudogroup approximations to reduce the search within a small number of elements. One of the main advantages of the pseudogroup hashing is the possibility of iterating to obtain more accurate representations of the targets in the spirit of the renormalization group approach. We describe the iterative pseudogroup hashing algorithm using the universal basis given by the braidings of Fibonacci anyons. An analysis of the efficiency of the iterations based on the random matrix theory indicates that the runtime and braid length scale poly-logarithmically with the final error, comparing favorably to the Solovay-Kitaev algorithm.
Embedding the Bilson-Thompson model in an LQG-like framework
Vaid, Deepak
2010-01-01
We argue that the Quadratic Spinor Lagrangian approach allows us to approach the problem of forming a geometrical condensate of spinorial tetrads in a natural manner. This, along with considerations involving the discrete symmetries of lattice triangulations, lead us to discover that the quasiparticles of such a condensate are tetrahedra with braids attached to its faces and that these braid attachments correspond to the preons in Bilson-Thompson's model of elementary particles. These "spatoms" can then be put together in a tiling to form more complex structures which encode both geometry and matter in a natural manner. We conclude with some speculations on the relation between this picture and the computational universe hypothesis.
Log jams and flood sediment buildup caused channel avulsion in the Pennsylvanian of Atlantic Canada
DEFF Research Database (Denmark)
Gibling, Martin R; Bashforth, Arden Roy; Falcon-Lang, Howard J;
2010-01-01
Accumulations of logs and flood sediment frequently block modern channels and may trigger avulsion, but these effects are difficult to demonstrate for the ancient record. Braided-fluvial channels in the Pennsylvanian South Bar Formation of Atlantic Canada contain sandstone successions up to 6 m...... thick of sigmoidal cross-beds, plane beds, and antidunes, deposited rapidly at highflow-stage. These strata are commonly capped by accumulations up to 2.5 m thick of flattened, coalified logs and coal intraclasts (originally peat fragments), many of which are overlain by mudstone laid down in abandoned...... channels. The logs include lycopsids, calamiteans, tree ferns, pteridosperms and cordaitaleans, inferred to have grown on inactive braided tracts near the channels. A compaction estimate suggests that one log accumulation was originally more than four times its present thickness. Most accumulations...
Feler, Yoel
2006-01-01
The configuration space C^n of unordered n-tuples of distinct points on a torus T^2 is a non-singular complex algebraic variety. We study holomorphic self-maps of C^n and prove that for n>4 any such map F either carries the whole of C^n into an orbit of the diagonal Aut(T^2) action in C^n or is of the form F(x)=T(x)x for some holomorphic map T:C^n-->Aut(T^2). We also prove that for n>4 any endomorphism of the torus braid group B_n(T^2) with a non-abelian image preserves the pure torus braid g...
DEFF Research Database (Denmark)
Randrup, Thomas; Røgen, Peter
1996-01-01
Take a strip of paper and 'twist' it, tie a knot on it, and glue its ends together. Then you obtain a closed, twisted, and knotted strip. We use this as a model for a class of geometric objects which we call the class of closed strips. We define the twisting number of a closed strip which is an...... invariant of ambient isotopy measuring the topological twist of the closed strip. We classify closed strips in euclidean 3-space by their knots and their twisting number. We prove that this classification exactly divides closed strips into isotopy classes. Using this classification we point out how some...... polynomial invariants for links lead to polynomial invariants for strip links. We give a method for knotting a strip with control on its twist, and our method includes a closed braid description of a closed strip. Finally, we generalize the notion of closed baids, allowing braids to be closed by any oriented...
Energy Technology Data Exchange (ETDEWEB)
Sick, M. [Lawrence Livermore National Lab., CA (United States)
1994-12-01
The Lawrence Livermore National Laboratory (LLNL) site rests upon 300-400 feet of highly heterogeneous braided stream sediments which have been contaminated by a plume of Volatile Organic Compounds (VOCs). The stream channels are filled with highly permeable coarse grained materials that provide quick avenues for contaminant transport. The plume of VOCs has migrated off site in the TFA area, making it the area of greatest concern. I mapped the paleo-stream channels in the TFA area using SLICE an LLNL Auto-CADD routine. SLICE constructed 2D cross sections and sub-horizontal views of chemical, geophysical, and lithologic data sets. I interpreted these 2D views as a braided stream environment, delineating the edges of stream channels. The interpretations were extracted from Auto-CADD and placed into Earth Vision`s 3D modeling and viewing routines. Several 3D correlations have been generated, but no model has yet been chosen as a best fit.
Institute of Scientific and Technical Information of China (English)
WANG Aijun; AO Qiang; HE Qing; GONG Xiaoming; GONG Kai; GONG Yandao; ZHAO Nanming; ZHANG Xiufang
2006-01-01
Neural stem cells (NSCs) are currently considered as powerful candidate seeding cells for regeneration of both spinal cords and peripheral nerves. In this study, NSCs derived from fetal rat cortices were co-cultured with chitosan to evaluate the cell affinity of this material. The results showed that NSCs grew and proliferated well on chitosan films and most of them differentiated into neuron-like cells after 4 days of culture. Then, molded and braided chitosan conduits were fabricated and characterized for their cytotoxicity, swelling, and mechanical properties. Both types of conduits had no cytotoxic effects on fibroblasts (L929 cells) or neuroblastoma (Neuro-2a) cells. The molded conduits are much softer and more flexible while the braided conduits possess much better mechanical properties, which suggests different potential applications.
Quench properties of high current superconductors
Energy Technology Data Exchange (ETDEWEB)
Garber, M; Sampson, W B
1980-01-01
A technique has been developed which allows the simultaneous determination of most of the important parameters of a high current superconductor. The critical current, propagation velocity, normal state resistivity, magnetoresistance, and enthalpy are determined as a function of current and applied field. The measurements are made on non-inductive samples which simulate conditions in full scale magnets. For wide, braided conductors the propagation velocity was found to vary approximately quadratically with current in the 2 to 5 kA region. A number of conductors have been tested including some Nb/sub 3/Sn braids which have critical currents in excess of 10 kA at 5 T, 4.2 K.
Barnes, Gwendolyn E; Szabo, Richard J
2014-01-01
We systematically study noncommutative and nonassociative algebras A and their bimodules as algebras and bimodules internal to the representation category of a quasitriangular quasi-Hopf algebra. We enlarge the morphisms of the monoidal category of A-bimodules by internal homomorphisms, and describe explicitly their evaluation and composition morphisms. For braided commutative algebras A the full subcategory of symmetric A-bimodule objects is a braided closed monoidal category, from which we obtain an internal tensor product operation on internal homomorphisms. We describe how these structures deform under cochain twisting of the quasi-Hopf algebra, and apply the formalism to the example of deformation quantization of equivariant vector bundles over a smooth manifold. Our constructions set up the basic ingredients for the systematic development of differential geometry internal to the quasi-Hopf representation category, which will be tackled in the sequels to this paper, together with applications to models o...
Some combinatorial models for reduced expressions in Coxeter groups
Denoncourt, Hugh
2011-01-01
Stanley's formula for the number of reduced expressions of a permutation regarded as a Coxeter group element raises the question of how to enumerate the reduced expressions of an arbitrary Coxeter group element. We provide a framework for answering this question by constructing combinatorial objects that represent the inversion set and the reduced expressions for an arbitrary Coxeter group element. The framework also provides a formula for the length of an element formed by deleting a generator from a Coxeter group element. Fan and Hagiwara, et al$.$ showed that for certain Coxeter groups, the short-braid avoiding elements characterize those elements that give reduced expressions when any generator is deleted from a reduced expression. We provide a characterization that holds in all Coxeter groups. Lastly, we give applications to the freely braided elements introduced by Green and Losonczy, generalizing some of their results that hold in simply-laced Coxeter groups to the arbitrary Coxeter group setting.
Conceptual designs of 50 kA 20 MJ superconducting ohmic heating coils
International Nuclear Information System (INIS)
Two designs of 20 Mj superconducting coils are described which were developed to demonstrate the feasibility of an ohmic heating system. NbTi and Nb;sub 3;Sn superconductors were considered for both 7 tesla and 9 tesla maximum fields. Cabled and braided conductors were investigated and the braided conductor is identified as the best alternative due to its high operating current densities and because of its porosity. The coils are designed to be cryostable for bipolar operation from +7 tesla to -7 tesla and from +9 tesla to -9 tesla maximum fields within 1 sec. The structural design addresses the distribution of structure and structural materials used in the pulsed field environment. Immersion cooled (pool boil) and forced flow cooled coils are described. 2 refs
Measurement of AC losses in different former materials
DEFF Research Database (Denmark)
Olsen, Søren Krüger; Træholt, Chresten; Kühle, Anders Van Der Aa;
1998-01-01
candidates separately; for example copper tubes, stainless steel braid, copper braid, corrugated stainless steel tubes, etc. The measured data are compared with the predictions of a theoretical model. Our results show that in most cases, the losses induced by eddy currents in the former are negligible......A high temperature superconducting cable may be based on a centrally located cylindrical support, a so-called former. If electrically conductive, the former can contribute to the AC losses through eddy current losses caused by unbalanced axial and tangential magnetic fields. With these measurements...... we aim at investigating the eddy current losses of commonly used former materials. A one layer cable conductor was wound on a glass fibre reinforced polymer (GRFP) former. By inserting a variety of materials into this, it was possible to measure the eddy current losses of each of the former...
Topological quantum gate construction by iterative pseudogroup hashing
Energy Technology Data Exchange (ETDEWEB)
Burrello, Michele; Mussardo, Giuseppe [International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste (Italy); Wan Xin, E-mail: burrello@sissa.it, E-mail: mussardo@sissa.it [Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784 (Korea, Republic of)
2011-02-15
We describe the hashing technique for obtaining a fast approximation of a target quantum gate in the unitary group SU(2) represented by a product of the elements of a universal basis. The hashing exploits the structure of the icosahedral group (or other finite subgroups of SU(2)) and its pseudogroup approximations to reduce the search within a small number of elements. One of the main advantages of the pseudogroup hashing is the possibility of iterating to obtain more accurate representations of the targets in the spirit of the renormalization group approach. We describe the iterative pseudogroup hashing algorithm using the universal basis given by the braidings of Fibonacci anyons. An analysis of the efficiency of the iterations based on the random matrix theory indicates that the runtime and braid length scale poly-logarithmically with the final error, comparing favorably to the Solovay-Kitaev algorithm.
Makeup your mind: The impact of styling on perceived competence and warmth of female leaders.
Klatt, Jennifer; Eimler, Sabrina C; Krämer, Nicole C
2016-01-01
Women are still underrepresented at the highest management levels. The think-manager-think-male phenomenon suggests that leadership is associated with male rather than female attributes. Although styling has been shown to influence the evaluation of women's leadership abilities, the relevant specific features have been left remarkably unaddressed. In a 2 × 2 × 2 × 2 (skirt/pants, with/without jewelry, loose hair/braid, with/without makeup) between-subjects design, 354 participants evaluated a woman in a photograph. Women with makeup, pants, or with jewelry were rated as more competent than women without makeup, with skirts, or without jewelry. A combination of loose hair and no makeup was perceived as warmest, and women with loose hair were more likely to be hired than those with braids. In sum, even subtle changes in styling have a strong impact on how women's leadership abilities are evaluated.
Influence of thermofixation on artificial ACL ligament dimensional and mechanical properties
Ben Abdessalem, S.; Jedda, H.; Skhiri, S.; Karray, S.; Dahmen, J.; Boughamoura, H.
2005-11-01
The anterior cruciate ligament (ACL) is the major articular ligamentous structure of the knee, it functions as a joint stabilizer. When ruptured, the natural ACL ligament can be replaced by a textile synthetic ligament such as a braid, knitted cord, or woven cord. Theses structures are composed of biocompatible materials such as polyester or Gore-Tex filaments. The success of an ACL replacement is widely linked to its mechanical and dimensional properties such as tensile strength, dimensional stability and resistance to abrasion. We introduced an additional treatment in the manufacturing of textile ACL ligaments based on the thermofixation of the textile structure by using textile industry stabilization techniques. Boiling water, saturated vapor and dry heat have been tested to stabilize a braided ligament made of Dacron polyester. The application of these three techniques led to shrinkage and an increase of breaking strength of the textile structure.
Novel biocompatible transversal pneumatic artificial muscles made of PDMS/PET satin composite
Directory of Open Access Journals (Sweden)
Szmechtyk Tomasz
2016-06-01
Full Text Available In this study novel transversal pneumatic artificial muscles (TPAM, made from composite – poly(dimethylsiloxane (PDMS matrix membrane and poly(ethylene terephthalate (PET satin reinforcement, are presented. Miniature TPAM consists of a flexible internal braid (IB reinforcing the membrane and the external braid (EB. EB, with fibers arranged transversely to the IB, is placed laterally. Differently prepared TPAMs were tested for their effectiveness as actuators for robot drive and the PDMS/PET composite suitability was evaluated for applications in human gastrointestinal tract (chemical resistance, thermal characteristic. FT-IR spectra of the composite were compared for study PDMS impregnation process of PET satin and effect of immersion in selected solution. The composite shows outstanding biocompatibility and the muscles have competitive static load characteristics in comparison with other pneumatic artificial muscles (PAM. These results lead to believe, that in the near future painless examination of the gastrointestinal tract using a secure robot will be possible.
Towards effective topological field theory for knots
Mironov, A
2015-01-01
Construction of (colored) knot polynomials for double-fat graphs is further generalized to the case when "fingers" and "propagators" are substituting R-matrices in arbitrary closed braids with m-strands. Original version of arXiv:1504.00371 corresponds to the case m=2, and our generalizations sheds additional light on the structure of those mysterious formulas. Explicit expressions are now combined from Racah matrices of the type $R\\otimes R\\otimes\\bar R\\longrightarrow \\bar R$ and mixing matrices in the sectors $R^{\\otimes 3}\\longrightarrow Q$. Further extension is provided by composition rules, allowing to glue two blocks, connected by an m-strand braid (they generalize the product formula for ordinary composite knots with m=1).
Test methods for textile composites
Minguet, Pierre J.; Fedro, Mark J.; Gunther, Christian K.
1994-01-01
Various test methods commonly used for measuring properties of tape laminate composites were evaluated to determine their suitability for the testing of textile composites. Three different types of textile composites were utilized in this investigation: two-dimensional (2-D) triaxial braids, stitched uniweave fabric, and three-dimensional (3-D) interlock woven fabric. Four 2-D braid architectures, five stitched laminates, and six 3-D woven architectures were tested. All preforms used AS4 fibers and were resin-transfer-molded with Shell RSL-1895 epoxy resin. Ten categories of material properties were investigated: tension, open-hole tension, compression, open-hole compression, in-plane shear, filled-hole tension, bolt bearing, interlaminar tension, interlaminar shear, and interlaminar fracture toughness. Different test methods and specimen sizes were considered for each category of test. Strength and stiffness properties obtained with each of these methods are documented in this report for all the material systems mentioned above.
Milestones Toward Majorana-Based Quantum Computing
Aasen, David; Hell, Michael; Mishmash, Ryan V.; Higginbotham, Andrew; Danon, Jeroen; Leijnse, Martin; Jespersen, Thomas S.; Folk, Joshua A.; Marcus, Charles M.; Flensberg, Karsten; Alicea, Jason
2016-07-01
We introduce a scheme for preparation, manipulation, and read out of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances in materials growth with tools commonly used in quantum-dot experiments, including gate control of tunnel barriers and Coulomb effects, charge sensing, and charge pumping. We outline a sequence of milestones interpolating between zero-mode detection and quantum computing that includes (1) detection of fusion rules for non-Abelian anyons using either proximal charge sensors or pumped current, (2) validation of a prototype topological qubit, and (3) demonstration of non-Abelian statistics by braiding in a branched geometry. The first two milestones require only a single wire with two islands, and additionally enable sensitive measurements of the system's excitation gap, quasiparticle poisoning rates, residual Majorana zero-mode splittings, and topological-qubit coherence times. These pre-braiding experiments can be adapted to other manipulation and read out schemes as well.
Affine and degenerate affine BMW algebras: Actions on tensor space
Daugherty, Zajj; Virk, Rahbar
2012-01-01
The affine and degenerate affine Birman-Murakami-Wenzl (BMW) algebras arise naturally in the context of Schur-Weyl duality for orthogonal and symplectic quantum groups and Lie algebras, respectively. Cyclotomic BMW algebras, affine and cyclotomic Hecke algebras, and their degenerate versions are quotients. In this paper we explain how the affine and degenerate affine BMW algebras are tantalizers (tensor power centralizer algebras) by defining actions of the affine braid group and the degenerate affine braid algebra on tensor space and showing that, in important cases, these actions induce actions of the affine and degenerate affine BMW algebras. We then exploit the connection to quantum groups and Lie algebras to determine universal parameters for the affine and degenerate affine BMW algebras. Finally, we show that the universal parameters are central elements--the higher Casimir elements for orthogonal and symplectic enveloping algebras and quantum groups.
Advanced resin systems and 3D textile preforms for low cost composite structures
Shukla, J. G.; Bayha, T. D.
1993-01-01
Advanced resin systems and 3D textile preforms are being evaluated at Lockheed Aeronautical Systems Company (LASC) under NASA's Advanced Composites Technology (ACT) Program. This work is aimed towards the development of low-cost, damage-tolerant composite fuselage structures. Resin systems for resin transfer molding and powder epoxy towpreg materials are being evaluated for processability, performance and cost. Three developmental epoxy resin systems for resin transfer molding (RTM) and three resin systems for powder towpregging are being investigated. Various 3D textile preform architectures using advanced weaving and braiding processes are also being evaluated. Trials are being conducted with powdered towpreg, in 2D weaving and 3D braiding processes for their textile processability and their potential for fabrication in 'net shape' fuselage structures. The progress in advanced resin screening and textile preform development is reviewed here.
Topology of algebraic curves an approach via dessins d'enfants
Degtyarev, Alex
2012-01-01
The book summarizes the state and new results on the topology of trigonal curves in geometrically ruled surfaces. Emphasis is placed upon various applications of the theory to related areas, most notably singularplane curves of small degree, elliptic surfaces, and Lefschetz fibrations (both complex and real), and Hurwitz equivalence of braid monodromy factorizations. The monograph conveys recent knowledge about related objects and is of interest to researchers and graduate students in the fields of topology and of complex and real algebraic varieties.
Institute of Scientific and Technical Information of China (English)
VALERIE; SARTOR
2007-01-01
A26-year-old woman,Yang Huiyan,currently tops Forbes list of the richest people in China:Her net worth rests at $16 billion.Clearly,Chinese women are getting into the capitalist spirit. Modem Beijing women no longer subsist as demure young virgins elegantly clad in silk qipao,long braids and downcast eyes. Today they’re hip power dressers who flaunt
Paillex, Amael
2010-01-01
Hydrological connectivity plays a major role in shaping both the habitat conditions and the biota in floodplain ecosystems. Current restoration strategies in large river floodplains often focus on the increase in lateral connectivity of secondary channels. However, the knowledge on the effect of restoration strategies on biodiversity remains limited. In this study, a framework was constructed to assess the level of lateral connectivity in thirteen cut-off channels of two braided sectors of th...
The Quantum Sine Gordon model in perturbative AQFT
Bahns, Dorothea
2016-01-01
We study the Sine Gordon model in the framework of perturbative algebraic quantum field theory, without making use of a representation on Fock space. In particular, we calculate the vertex operator algebra braiding property. We prove that in the finite regime of the model, the vacuum expectation value of the Epstein Glaser $S$-matrix and the interacting current, both given as formal power series, converge in a suitable topology on the space of functionals.
Novel tests and inspection methods for textile reinforced composite tubes
W. Hufenbach; Kroll, L; Gude, M.; A. Czulak; Böhm, R.; M. Danczak
2005-01-01
Purpose: This paper describes innovative lightweight applications of fiber and textile reinforced polymers in aircraft, automotive and chemical industry.Design/methodology/approach: This paper deals with modern test methods of braided composite tube specimens as basic elements of modern composites. The tubes subjected to strength tests under superposed compressive, tensile and internal pressure loadings, and tested by the acoustic emission method for damage detection.Findings: For the quality...
A new approach to spin and statistics
Kuckert, B
1994-01-01
We give an algebraic proof of the spin-statistics connection for the parabosonic and parafermionic quantum topological charges of a theory of local observables with a modular PCT-symmetry. The argument avoids the use of the spinor calculus and also works in 1+2 dimensions. It is expected to be a progress towards a general spin-statistics theorem including also (1+2)-dimensional theories with braid group statistics.
Huyghe, P.; Mugnier, J. L.; Gajurel, A.P.; Delcaillau, B.
2005-01-01
A multidisciplinary study was conducted on the section of the Siwalik Group sediments, approximately 5000 m thick, exposed along the Karnali River. Analysis of facies, clay mineralogy and neodymium isotope compositions revealed significant changes in the sedimentary record, allowing discussion of their tectonic or climatic origin. Two major changes within the sedimentary fill were detected: the change from a meandering to a braided river system at ca 9.5 Ma and the change from a deep sandy br...
A Jacobi identity for intertwining operator algebras
Huang, Y Z
1997-01-01
We find a Jacobi identity for intertwining operator algebras. Most of the main properties of genus-zero conformal field theories, including the main properties of vertex operator algebras, modules, intertwining operators, Verlinde algebras, and fusing and braiding matrices, are incorporated into this identity. We prove that intertwining operators for a suitable vertex operator algebra satisfy this Jacobi identity. Two equivalent definitions of intertwining operator algebra in terms of this Jacobi identity are given.
Sudo, Hideki; Abumi, K.; Ito, M; Y. Kotani
2002-01-01
The sublaminar wiring procedure has been commonly used for stabilizing the atlantoaxial complex. Multistrand braided cables were introduced in the early 1990s. In previous biomechanical studies these cables were demonstrated to be superior to monofilament wires in terms of their flexibility, mechanical strength, and fatigue-related characteristics. To the authors' knowledge, they are the first to describe clinically the occurrence of delayed spinal cord compression resulting from multistrand ...
Multifunctional composites : healing, heating and electromagnetic integration
Plaisted, Thomas Anthony John
2007-01-01
Multifunctional materials, in the context of this research, integrate other functions into materials that foremost have outstanding structural integrity. Details of the integration of electromagnetic, heating, and healing functionalities into fiber-reinforced polymer composites are presented. As a result of fiber/wire integration through textile braiding and weaving, the dielectric constant of a composite may be tuned from negative to positive values. These wires are further leveraged to unif...
One Kind of Routing Algorithm Modified in Wireless Sensor Network
Wei Ni Ni; Song Yi
2016-01-01
The wireless sensor networks are the emerging next generation sensor networks, Routing technology is the wireless sensor network communication layer of the core technology. To build reliable paths in wireless sensor networks, we can consider two ways: providing multiple paths utilizing the redundancy to assure the communication reliability or constructing transmission reliability mechanism to assure the reliability of every hop. Braid multipath algorithm and ReInforM routing algorithm are the...
Elucidation of differential mineralisation on native and regenerated silk matrices.
Midha, Swati; Tripathi, Rohit; Geng, Hua; Lee, Peter D; Ghosh, Sourabh
2016-11-01
Bone mineralisation is a well-orchestrated procedure triggered by a protein-based template inducing the nucleation of hydroxyapatite (HA) nanocrystals on the matrix. In an attempt to fabricate superior nanocomposites from silk fibroin, textile braided structures made of natively spun fibres of Bombyx mori silkworm were compared against regenerated fibroin (lyophilized and films) underpinning the influence of intrinsic properties of fibroin matrices on HA nucleation. We found that native braids could bind Ca(2+) ions through electrostatic attraction, which initiated the nucleation and deposition of HA, as evidenced by discrete shift in amide peaks via ATR-FTIR. This phenomenon also suggests the involvement of amide linkages in promoting HA nucleation on fibroin. Moreover, CaCl2-SBF immersion of native braids resulted in preferential growth of HA along the c-axis, forming needle-like nanocrystals and possessing Ca/P ratio comparable to commercial HA. Though regenerated lyophilized matrix also witnessed prominent peak shift in amide linkages, HA growth was restricted to (211) plane only, albeit at a significantly lower intensity than braids. Regenerated films, on the other hand, provided no crystallographic evidence of HA deposition within 7days of SBF immersion. The present work sheds light on the primary fibroin structure of B. mori which probably plays a crucial role in regulating template-induced biomineralisation on the matrix. We also found that intrinsic material properties such as surface roughness, geometry, specific surface area, tortuosity and secondary conformation exert influence in modulating the extent of mineralisation. Thus our work generates useful insights and warrants future studies to further investigate the potential of bone mimetic, silk/mineral nanocomposite matrices for orthopaedic applications.
Quantum logic as superbraids of entangled qubit world lines
Yepez, Jeffrey
2009-01-01
Presented is a topological representation of quantum logic that views entangled qubit spacetime histories (or qubit world lines) as a generalized braid, referred to as a superbraid. The crossing of world lines is purely quantum in nature, most conveniently expressed analytically with ladder-operator-based quantum gates. At a crossing, independent world lines can become entangled. Complicated superbraids are systematically reduced by recursively applying novel quantum skein relations. If the s...
Implementasi Prinsip Corporate Social Responsibility (CSR) Dalam Sistem Hukum Indonesia
Purba, Hasim
2010-01-01
Corporate social responsibility is company moral responsibility to society. That responsibility moral is given to the society where company run its activity. Considering company role having a purpose to obtain;get the profite, but one side, the company also have to braid the harmonious relation/link with the society, hence principal function of social responsibility of company become important progressively to be paid attention to and implementation. Therefore principal applying of corpor...
Colored HOMFLY Polynomials as Multiple Sums over Paths or Standard Young Tableaux
Directory of Open Access Journals (Sweden)
A. Anokhina
2013-01-01
Full Text Available If a knot is represented by an m-strand braid, then HOMFLY polynomial in representation R is a sum over characters in all representations Q∈R⊗m. Coefficients in this sum are traces of products of quantum ℛ^-matrices along the braid, but these matrices act in the space of intertwiners, and their size is equal to the multiplicity MRQ of Q in R⊗m. If R is the fundamental representation R=[1]=□, then M□Q is equal to the number of paths in representation graph, which lead from the fundamental vertex □ to the vertex Q. In the basis of paths the entries of the m-1 relevant ℛ^-matrices are associated with the pairs of paths and are nonvanishing only when the two paths either coincide or differ by at most one vertex, as a corollary ℛ^-matrices consist of just 1×1 and 2×2 blocks, given by very simple explicit expressions. If cabling method is used to color the knot with the representation R, then the braid has as many as m|R| strands; Q have a bigger size m|R|, but only paths passing through the vertex R are included into the sums over paths which define the products and traces of the m|R|-1 relevant ℛ^-matrices. In the case of SU(N, this path sum formula can also be interpreted as a multiple sum over the standard Young tableaux. By now it provides the most effective way for evaluation of the colored HOMFLY polynomials, conventional or extended, for arbitrary braids.
On Ternary Quotients of Cubic Hecke Algebras
Cabanes, Marc; Marin, Ivan
2012-08-01
We prove that the quotient of the group algebra of the braid group introduced by Funar (Commun Math Phys 173:513-558, 1995) collapses in characteristic distinct from 2. In characteristic 2 we define several quotients of it, which are connected to the classical Hecke and Birman-Wenzl-Murakami quotients, but which admit in addition a symmetry of order 3. We also establish conditions on the possible Markov traces factorizing through it.
Zhuoshun Yang; Biao Zhang; Dapeng Li; Meng Lv; Chunmei Huang; Guan-Xin Shen; Bo Huang
2010-01-01
Tumor immunosuppression is commonly braided with chronic inflammation during tumor development. However, the relationship between immunosuppression and inflammation in tumor microenvironment is still unclear. We have demonstrated that mast cells are accumulated and exacerbate the inflammation and immunosuppression in tumor microenvironment via SCF/c-kit signaling pathway. Here, we further elucidate the underlying mechanism, which involves both myeloid-derived suppressor cells (MDSCs) and regu...
Actinomyces associated with persistent vaginal granulation tissue.
David L. Hemsell; Momin T Siddiqui; Chang, Joe S.; Drewes, Peter G.; Nihira, Mikio A; Clifford Y. Wai
2005-01-01
BACKGROUND: We report a case of symptomatic actinomycosis associated with vaginal suture erosion and granulation tissue refractory to conservative management, in an outpatient setting. CASE: Three months after total vaginal hysterectomy and uterosacral ligament vaginal vault suspension, a woman complained of painless, intermittent vaginal discharge and spotting. Despite cauterization of granulation tissue, vaginal spotting persisted for another month. On re-examination, braided polyester sutu...
Seifert surfaces in open books, and a new coding algorithm for links
Furihata, Rei; Hirasawa, Mikami; Kobayashi, Tsuyoshi
2005-01-01
We introduce a new standard form of a Seifert surface $F$. In that standard form, $F$ is obtained by successively plumbing flat annuli to a disk $D$, where the gluing regions are all in $D$. We show that any link has a Seifert surface in the standard form, and thereby present a new way of coding a link. We present an algorithm to read the code directly from a braid presentation.
Shaanxi Youth Folk Art Troupe Performs at Los Angeles Disneyland
Institute of Scientific and Technical Information of China (English)
Liu; Tong
2015-01-01
At the central square of Disneyland in Los Angeles during the Chinese Spring Festival,a group of Chinese children wearing horn-shaped braids or white towel kerchiefs on their heads performed the waist-drum dance to the rhythm of typical northern Shaanxi folk music.The wonderful performance given by the Shaanxi Youth Folk Art Troupe at Disneyland was part of a cultural exchange with the United States
On the relation between the modular double of U{sub q}(sl(2,R)) and the quantum Teichmueller theory
Energy Technology Data Exchange (ETDEWEB)
Nidaiev, Iurii; Teschner, Joerg
2013-02-15
We exhibit direct relations between the modular double of U{sub q}(sl(2,R)) and the quantum Teichmueller theory. Explicit representations for the fusion- and braiding operations of the quantum Teichmueller theory are immediate consequences. Our results include a simplified derivation of the Clebsch-Gordan decomposition for the principal series of representation of the modular double of U{sub q}(sl(2,R)).
Jessell, Mark; Boamah, K.; Duodu, J. A.; Ley-Cooper, Y.
2015-01-01
We have identified a 230 km long palaeochannel cutting through the sediments of the Obosum Group within the Volta Basin, Ghana. The channel is visible in regional airborne magnetic data as a pair of parallel magnetic anomalies which we interpret to be lateral terrace placer deposits of magnetite or maghemite and show both meandering and braided geometries. The palaeochannel is also visible in the airborne radiometric data for part of its length, as well as in airborne electromagnetic data, wh...
On the Y555 complex reflection group
Allcock, Daniel
2008-01-01
We give a computer-free proof of a theorem of Basak, describing the group generated by 16 complex reflections of order 3, satisfying the braid and commutation relations of the Y555 diagram. The group is the full isometry group of a certain lattice of signature (13,1) over the Eisenstein integers Z[cube root of 1]. Along the way we enumerate the cusps of this lattice and classify the root and Niemeier lattices over this ring.
Method for Coating a Tow with an Electrospun Nanofiber
Kohlman, Lee W. (Inventor); Roberts, Gary D. (Inventor)
2015-01-01
Method and apparatus for enhancing the durability as well as the strength and stiffness of prepreg fiber tows of the sort used in composite materials are disclosed. The method involves adhering electrospun fibers onto the surface of such composite materials as filament-wound composite objects and the surface of prepreg fiber tows of the sort that are subsequently used in the production of composite materials of the filament-wound, woven, and braided sorts. The apparatus performs the methods described herein.
Directory of Open Access Journals (Sweden)
Sardenberg Trajano
2003-01-01
Full Text Available Surgical materials of monofilament nylon (0, 3-0 and 4-0, braided polyester (0, 3-0 and 4-0 and monofilament polypropylene (0, 3-0 and 4-0 of 7 trademarks commercialized in Brazil, was submitted to analysis of diameter, length, enchasement resistance, tensile strength of surgery materials knotted and unknotted, according to ABNT. The results show that most of surgical materials was inside of preconizing patterns of ABNT.
Fractal Kelvin-Helmholtz breakups
Fontane, Jérôme; Joly, Laurent; Reinaud, Jean
2008-01-01
The Kelvin–Helmholtz billow developing in an infinite- Schmidt number mixing layer at Re=1500 between two density-contrasted fluids experiences a two-dimensional shear instability. Secondary Kelvin–Helmholtz billows are seen to emerge on the light side of the primary structure, and then are advected towards the core of the main billow as the wave overturns. Due to the inertial baroclinic vorticity production, the braid region turns into a sharp vorticity ridge holding high shear levels and...
Réduction dimensionnelle pour des milieux hétérogènes, troués ou fissurés
Babadjian, Jean-François
2005-01-01
Andrea BRAIDES : Rapporteur Antonin CHAMBOLLE : Rapporteur Gilles FRANCFORT : Directeur de thèse Olivier LAFITTE : Examinateur Hervé LE DRET : Examinateur Jean-Jacques MARIGO : Président du jury This thesis is concerned with the justification of membrane models as zero-thickness limits of three dimensional nonlinear "elastic behavior" (the quotes refer to the absence of the usual requirement that the energy should blow up as the Jacobian of the transformation tends to zero). The dimensiona...
Effect of Cold Plasma Treatment on the Mechanical Properties of RTM Composites
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM wasused to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result shows that thesurface polarity of carbon fibers was modified by cold plasma treatment, which increases the impregnation of PETbraided carbon fibers during the process of resin flowing, improves the interfacial properties of RTM composites, andtherefore enhances the mechanical properties of the KTM composites.
McFee, W. E.; Pennington, P.L.; Burdett, L. G.; Powell, J. W. B.; Schwacke, J. H.; Dockery, F. E.
2007-01-01
A study was conducted in October 2006 in the Charleston, South Carolina area to test the movements of three different buoy line types to determine which produced a preferred profile that could reduce the risk of dolphin entanglement. Tests on diamond-braided nylon commonly used in the crab pot fishery were compared with stiffened line of Esterpro and calf types in both shallow and deep water environments using DSTmilli data loggers. Loggers were placed at intervals along the lines to record d...
Graded self-dual fusion categories of rank $4$
Dong, Jingcheng; Zhang, Liangyun; Dai, Li
2016-01-01
We classify self-dual spherical fusion categories of rank $4$ with non-trivial universal grading. We prove that they are Grothendieck equivalent to a Deligne's tensor product $\\A\\boxtimes\\B$, where $\\A$ is a non-pointed fusion category of rank $2$, $\\B$ is a pointed fusion category of rank $2$. In particular, if they are braided then they are equivalent to $\\A\\boxtimes\\B$.
Statistics in the Propositional Formulation of Quantum Mechanics
Grigore, Dan Radu
1993-01-01
We give a definition for the notion of statistics in the lattice-theoretical (or propositional) formulation of quantum mechanics of Birchoff, von Neumann and Piron. We show that this formalism is compatible only with two types of statistics: Bose-Einstein and Fermi-Dirac. Some comments are made about the connection between this result and the existence of exotic statistics (para-statistics, infinite statistics, braid statistics).
Topological Quantum Computation with the universal R matrix for Ising anyons
Georgiev, Lachezar S
2008-01-01
We show that the braid-group extension of the monodromy-based topological quantum computation scheme of Das Sarma et al. can be understood in terms of the universal R matrix for the Ising model giving similar results to those obtained by direct analytic continuation of multi-anyon Pfaffian wave functions. It is necessary, however, to take into account the projection on spinor states with definite total parity which is responsible for the topological entanglement in the Pfaffian topological quantum computer.
Słowik, Marcin
2015-12-01
Palaeoenvironmental and palaeohydrological reconstructions can provide important guidance for river restoration projects. This paper reconstructs the trajectory of river pattern changes of a lowland river (the Obra River, western Poland) as a basis to inform realistic restoration activities. The history of river changes is reconstructed for the last 12,700 radiocarbon years BP. The sequence and timing of change differ from widely recognized, conventional assessments of transitions from braided to meandering planforms in the Polish Lowlands. Traces of a laterally migrating anabranching system were found in the middle Obra valley. In its lower course, a transition from a braided to meandering planform took place later than in other rivers of the Polish Lowlands. Sediment delivery from parts of the catchment situated downstream of lakes in the river course could have been the main reason for maintenance of the braided pattern. Restoration scenarios that take into account the trajectory of river planform changes are hypothesized in relation to variations of sediment supply and degree of anthropogenic impact.
Directory of Open Access Journals (Sweden)
Bertrand Tondu
2014-06-01
Full Text Available We analyze the possibility of taking advantage of artificial muscle’s own stiffness and damping, and substituting it for a classic proportional-integral-derivative controller (PID controller an I controller. The advantages are that there would only be one parameter to tune and no need for a dynamic model. A stability analysis is proposed from a simple phenomenological artificial muscle model. Step and sinus-wave tracking responses performed with pneumatic McKibben muscles are reported showing the practical efficiency of the method to combine accuracy and load robustness. In the particular case of the McKibben artificial muscle technology, we suggest that the dynamic performances in stability and load robustness would result from the textile nature of its braided sleeve and its internal friction which do not obey Coulomb’s third law, as verified by preliminary reported original friction experiments. Comparisons are reported between three kinds of braided sleeves made of rayon yarns, plastic, and thin metal wires, whose similar closed-loop dynamic performances are highlighted. It is also experimentally shown that a sleeve braided with thin metal wires can give high accuracy performance, in step as in tracking response. This would be due to a low static friction coefficient combined with a kinetic friction exponentially increasing with speed in accordance with hydrodynamic lubrication theory applied to textile physics.
Colored HOMFLY polynomials as multiple sums over paths or standard Young tableaux
Anokhina, A; Morozov, A; Morozov, An
2013-01-01
If a knot is represented by an m-strand braid, then HOMFLY polynomial in representation R is a sum over characters in all representations Q\\in R^{\\otimes m}. Coefficients in this sum are traces of products of quantum R-matrices along the braid, but these matrices act in the space of intertwiners, and their size is equal to the multiplicity M_{RQ} of Q in R^{\\otimes m}. If R is the fundamental representation R=[1], then M_{[1] Q} is equal to the number of paths in representation graph, which lead from the fundamental vertex [1] to the vertex Q. In the basis of paths the entries of the m-1 relevant R-matrices are associated with the pairs of paths and are non-vanishing only when the two paths either coincide or differ by at most one vertex; as a corollary R-matrices consist of just 1x1 and 2x2 blocks, given by very simple explicit expressions. If cabling method is used to color the knot with the representation R, then the braid has m|R| strands, Q have a bigger size m|R|, but only paths passing through the vert...
International Nuclear Information System (INIS)
The host rocks of Qianjiadian uranium deposit in Songliao basin is composed of thick bed sand- bodies, which are formed by braided stream sediment in Yaojia formation. The thick bed sandbody has favorable upper and lower waterproof layer, and has lenticular mudstone interlayer in some parts. On plane, the flood plain face locates around the braided stream face, which is mainly composed of sediments of argillaceous rock. In the middle of braided stream, distributes interchannel sediments, which has thicker mudstone interlayer and thinner sand bodies, and the sand body of these place is more heterogeous than others. Based on the analysis on oxidation zone and uranium mineralization, it is found that the distribution and configuration of oxidation zone and ore bodies are obviously controlled by the lithofaties characteristics and sandbody heterogeneity of Yaojia formation. The reason is that the movement of uranium-bearing oxidizing ground water can be obstructed by interchannel sediments and pelitic interbeds of host sandstones. As a result, the redox interface will be developed and uranium can be concentrated in neighbouring sandstones. The sandbodies with greater homogeneity are favorable for the formation of oxidation zone, and sandbodies with greater heterogeneity are favorable for the uranium mineralization. (authors)
Baucom, P.C.; Rigsby, C.A.
1999-01-01
Strata exposed in terraces and modern cutbanks along the Rio Desaguadero contain a variety of lithofacies that were deposited in four distinct facie??s associations. These facie??s associations document a history of aggradation and downcutting that is linked to Holocene climate change on the Altiplano. Braided-stream, meandering-stream, deltaic and shoreline, and lacustrine sediments preserved in multi-level terraces in the northern Rio Desaguadero valley record two high-water intervals: one between 4500 and 3900 yr BP and another between 2000 and 2200 yr BP. These wet periods were interrupted by three periods of fluvial downcutting, centered at approximately 4000 yr BP, 3600 yr BP, and after 2000 yr BP. Braided-river sediments preserved in a single terrace level in the southern Rio Desaguadero valley record a history of nearly continuous fluvial sedimentation from at least 7000 yr BP until approximately 3200 yr BP that was followed by a single episode (post-3210 yr BP) of downcutting and lateral migration. The deposition and subsequent fluvial downcutting of the northern strata was controlled by changes in effective moisture that can be correlated to Holocene water-level fluctuations of Lake Titicaca. The deposition and dissection of braided-stream sediments to the south are more likely controlled by a combination of base-level change and sediment input from the Rio Mauri. Copyright ??1999, SEPM (Society for Sedimentar)- Geology).
Energy Technology Data Exchange (ETDEWEB)
Baucom, P.C.; Rigsby, C.A. [East Carolina Univ., Greenville, NC (United States). Dept. of Geology
1999-05-01
Strata exposed in terraces and modern cutbanks along the Rio Desaguadero contain a variety of lithofacies that were deposited in four distinct facies associations. These facies associations document a history of aggradation and downcutting that is linked to Holocene climate change on the Altiplano. Braided-stream, meandering-stream, deltaic and shoreline, and lacustrine sediments preserved in multi-level terraces in the northern Rio Desaguadero valley record two high-water intervals: one between 4,500 and 3,900 yr BP and another between 2,000 and 2,200 yr BP. These wet periods were interrupted by three periods of fluvial downcutting, centered at approximately 4,000 yr BP, 3,600 yr BP, and after 2,000 yr BP. Braided-river sediments preserved in a single terrace level in the southern Rio Desaguadero valley record a history of nearly continuous fluvial sedimentation from at least 7,000 yr BP until approximately 3,200 yr BP that was followed by a single episode (post-3,210 yr BP) of down-cutting and lateral migration. The deposition and subsequent fluvial downcutting of the northern strata was controlled by changes in effective moisture that can be correlated to Holocene water-level fluctuations of Lake Titicaca. The deposition and dissection of braided-stream sediments to the south are more likely controlled by a combination of base-level change and sediment input from the Rio Mauri.
Olsen, Henrik
1989-02-01
Studies of fluvial sandstone-body structures in the Lower Jurassic Dinosaur Canyon Member suggest a threefold subdivision of the ephemeral stream deposits. Sandstone-sheets with interbedded siltstones are less than 1 m thick and laterally extensive for hundreds of metres. They are interpreted as sheetflood deposits. Simple channel sandstone-bodies are a few metres thick and a few tens of metres wide. They reflect solitary channel incision, episodic migration and plugging. Multistorey channel sandstone-bodies are a few metres thick and laterally extensive for hundreds of metres. They are composed of several channel-shaped storeys and exhibit only local incision. The multistorey sandstone-bodies are interpreted as braided ephemeral stream deposits. Two sandstone-sheet subtypes with grooves and mounds, respectively, are interpreted as intermediate between the sheetflood deposits and solitary incised channel deposits on one hand and between sheetflood deposits and braided stream deposits on the other hand. The solitary channels and braided streams are accordingly interpreted to be initiated from sheetfloods through differential erosion and differential deposition, respectively. This model of channel evolution from sheetfloods is probably applicable to other semiarid and arid fluvial environments dominated by surface runoff.
You, Yizhi; Cho, Gil Young; Hughes, Taylor L.
2016-08-01
In this paper, we investigate the theory of dynamical axion strings emerging from chiral symmetry breaking in three-dimensional Weyl semimetals. The chiral symmetry is spontaneously broken by a charge density wave (CDW) order which opens an energy gap and converts the Weyl semimetal into an axion insulator. Indeed, the phase fluctuations of the CDW order parameter act as a dynamical axion field θ (x ⃗,t ) and couple to electromagnetic field via Lθ=θ/(x ⃗,t ) 32 π2 ɛσ τ ν μFσ τFν μ. Additionally, when the axion insulator is coupled to deformations of the background geometry/strain fields via torsional defects, e.g., screw dislocations, there is interesting interplay between the crystal dislocations and dynamical axion strings. For example, the screw dislocation traps axial charge, and there is a Berry phase accumulation when an axion string (which carries axial flux) is braided with a screw dislocation. In addition, a cubic coupling between the axial current and the geometry fields is nonvanishing and indicates a Berry phase accumulation during a particular three-loop braiding procedure where a dislocation loop is braided with another dislocation and they are both threaded by an axion string. We also observe a chiral magnetic effect induced by a screw dislocation density in the absence of a nodal energy imbalance between Weyl points and describe an additional chiral geometric effect and a geometric Witten effect.
TEXTILE STRUCTURES FOR AERONAUTICS (PART II
Directory of Open Access Journals (Sweden)
SOLER Miquel
2014-05-01
Full Text Available Three-dimensional (3D textile structures with better delamination resistance and damage impact tolerance to be applied in composites for structural components is one of the main goals of the aeronautical industry. Textile Research Centre in Canet de Mar has been working since 2008 in this field. Our staff has been designing, developing and producing different textile structures using different production methods and machinery to improve three-dimensional textile structures as fiber reinforcement for composites. This paper describes different tests done in our textile labs from unidirectional structures to woven, knitted or braided 3 D textile structures. Advantages and disadvantages of each textile structure are summarized. The second part of this paper deals with our know-how in the manufacturing and assessing of three-dimensional textile structures during this last five years in the field of textile structures for composites but also in the development of structures for other applications. In the field of composites for aeronautic sector we have developed textile structures using the main methods of textile production, that is to say, weaving, warp knitting, weft knitting and braiding. Comparing the advantages and disadvantages it could be said that braided fabrics, with a structure in the three space axes are the most suitable for fittings and frames.
The Jones polynomial: quantum algorithms and applications in quantum complexity theory
Yard, J; Yard, Jon; Wocjan, Pawel
2006-01-01
We analyze relationships between the Jones polynomial and quantum computation. Our first result is a polynomial-time quantum algorithm which gives an additive approximation of the Jones polynomial, in the sense of Bordewich, Freedman, Lovasz and Welsh, of any link obtained from a certain general family of closures of braids, evaluated at any primitive root of unity. This family encompasses the well-known plat and trace closures, generalizing results recently obtained by Aharonov, Jones and Landau. We base our algorithm on a local qubit implementation of the unitary Jones-Wenzl representations of the braid group which makes the underlying representation theory apparent, allowing us to provide an algorithm for approximating the HOMFLYPT two-variable polynomial of the trace closure of a braid at certain pairs of values as well. Next, we provide a self-contained proof that any quantum computation can be replaced by an additive approximation of the Jones polynomial, evaluated at almost any primitive root of unity....
Experimental Results in Support of Simulating Progressive Crush in Carbon-Fiber Textile Composites
Energy Technology Data Exchange (ETDEWEB)
DeTeresa, S J; Allison, L M; Cunningham, B J; Freeman, DC; Saculla, M D; Sanchez, R J; Winchester, S W
2001-04-02
This report summarizes the findings of an experimental program conducted to support the modeling of the crush behavior of triaxial braid carbon fiber composites. The matrix material as well as braided panels and tubes were characterized in order to determine material properties, to assess failure modes, and to provide a test bed for new analytical and numerical tools developed specifically for braided composites. The matrix material selected by the ACC was an epoxy vinyl ester (Ashland Hetron 922). Tensile tests were used to compare two formulations-one used by the ACC and one recommended by the resin supplier. The latter was a faster reacting system and gelled in one-third the time of the ACC formulation. Both formulations had an average elongation at failure that was only half of the resin supplier's reported value. Only one specimen of each type came close to the reported elongation value and it was shown that failure invariably initiated at both surface and internal defects. Overall, the tensile properties of the two formulations were nearly identical, but those of the ACC system were more consistent. The properties of the ACC matrix formulation were measured in tension, shear, and compression and the average properties obtained in these tests are summarized.
Energy Technology Data Exchange (ETDEWEB)
Ye, Liangmiao; Yang, Kexian [Univ. of Tulsa, OK (United States)
1997-08-01
Outcrop studies of the Bluejacket Sandstone (Middle Pennsylvanian) provide significant insights to reservoir architecture of the subsurface equivalent Bartlesville Sandstone. Quarry walls and road cuts in the Lake Eufaula area offer excellent exposures for detailed facies architectural investigations using high-precision surveying, photo mosaics. Directional minipermeameter measurements are being conducted. Subsurface studies include conventional logs, borehole image log, and core data. Reservoir architectures are reconstructed in four hierarchical levels: multi-storey sandstone, i.e. discrete genetic intervals; individual discrete genetic interval; facies within a discrete genetic interval; and lateral accretion bar deposits. In both outcrop and subsurface, the Bluejacket (Bartlesville) Sandstone comprises two distinctive architectures: a lower braided fluvial and an upper meandering fluvial. Braided fluvial deposits are typically 30 to 80 ft thick, and are laterally persistent filling an incised valley wider than the largest producing fields. The lower contact is irregular with local relief of 50 ft. The braided-fluvial deposits consist of 100-400-ft wide, 5-15-ft thick channel-fill elements. Each channel-fill interval is limited laterally by an erosional contact or overbank deposits, and is separated vertically by discontinuous mudstones or highly concentrated mudstone interclast lag conglomerates. Low-angle parallel-stratified or trough cross-stratified medium- to coarse-grained sandstones volumetrically dominate. This section has a blocky well log profile. Meandering fluvial deposits are typically 100 to 150 ft thick and comprise multiple discrete genetic intervals.
Quantum logic gates from Dirac quasiparticles
Marino, E. C.; Brozeguini, J. C.
2015-03-01
We show that one of the fundamental operations of topological quantum computation, namely the non-Abelian braiding of identical particles, can be physically realized in a general system of Dirac quasiparticles in 1 + 1D. Our method is based on the study of the analytic structure of the different Euclidean correlation functions of Dirac fields, which are conveniently expressed as functions of a complex variable. When the Dirac field is an (Abelian) anyon with statistics parameter s (2s not an integer), we show that the associated Majorana states of such a field present non-Abelian statistics. The explicit form of the unitary, non-commuting (monodromy) matrices generated upon braiding is derived as a function of s and is shown to satisfy the Yang-Baxter algebra. For the special case of s = 1/4, we show that the braiding matrices become the logic gates NOT, CNOT,… required in the algorithms of universal quantum computation. We suggest that maybe polyacetylene, alternately doped with alkali and halogen atoms, is a potential candidate for a physical material realization of the system studied here.
Institute of Scientific and Technical Information of China (English)
王哲; 金振奎; 付晶; 郭守波
2013-01-01
-west trending.The whole Badaowan Formation deposition in the time and space distribution has the inheritance and variability.The Badaowan Group in the study area mainly developed three kinds of deposition types,which are braided,braided fiver deltas and lakes,five kinds of sedimentary subfacies types and 10 kinds of sedimentary microfacies type.Braid-river deposits in the study area including the braided channel subfacies and floodplain subfacies,expressed as the peculiar asymmetry of the braided river "dual structure" in vertical.Braided river delta deposition of the study area included braided river delta plain subfacies,braided river delta front subfacies.Viewing from the position of the sand body developing in the sequence,the reservoir sand bodies develop mainly in the low and high system tract,regional mudstone caprock mainly develop in the transgressive systems tract.The Badaowan formation in Dishuiquan area mainly develop two sets of large reservoir-cap combination.JSQ1 lowstand system tract formation of braided channel sand body has the role of filling the early valleys,also can be used as good reservoir.JSQ1 lake transgressive system tract formation of lacustrine facies mudstone can be used as underlying reservoir favorable cover; JSQ1 high system tract and JSQ2 lowstand system tract formation of braided river delta distributary channel sand body and JSQ2 lake transgressive system tract of lake deposition can be combined to form a reservoir seal assemblage.Due to the JSQ lowstand system tract developing braided channel sand body,the lateral variation in lithology easy to form the oil and gas lateral occlusion.Therefore,the palaeogeomorphology of valley in study area of Badaowan Formation can be combined with widely distributed braided channel sand body of JSQ1 in the lowstand systems tract to form formation-lithologic trap which is the most favorable exploration targets in the study area.%运用层序地层学与沉积学的原理和方法,建立滴水泉地区侏罗
Colored HOMFLY polynomials of knots presented as double fat diagrams
Mironov, A; Morozov, An; Ramadevi, P; Singh, Vivek Kumar
2015-01-01
Many knots and links in S^3 can be drawn as gluing of three manifolds with one or more four-punctured S^2 boundaries. We call these knot diagrams as double fat graphs whose invariants involve only the knowledge of the fusion and the braiding matrices of four-strand braids. Incorporating the properties of four-point conformal blocks in WZNW models, we conjecture colored HOMFLY polynomials for these double fat graphs where the color can be rectangular or non-rectangular representation. With the recent work of Gu-Jockers, the fusion matrices for the non-rectangular [21] representation, the first which involves multiplicity is known. We verify our conjecture by comparing with the [21] colored HOMFLY of many knots, obtained as closure of three braids. The conjectured form is computationally very effective leading to writing [21]-colored HOMFLY polynomials for many pretzel type knots and non-pretzel type knots. In particular, we find class of pretzel mutants which are distinguished and another class of mutants whic...
Low-Cost Production of Composite Bushings for Jet Engine Applications
Gray, Robert A.
1998-01-01
The objectives of this research program were to reduce the manufacturing costs of variable stator vane bushings by 1) eliminating the expensive carbon fiber braiding operation, 2) replacing the batch mode impregnation, B-stage, and cutting operations with a continuous process, and 3) reducing the molding cycle and machining operations with injection molding to achieve near-net shapes. Braided bushings were successfully fabricated with both AMB-17XLD and AMB-TPD resin systems. The composite bushings achieved high glass transition temperature after post-cure (+300 C) and comparable weight loss to the PNM-15 bushings. ANM-17XLD bushings made with "batch-mode" molding compound (at 0.5 in. fiber length) achieved a +300 lb-force flange break strength which was superior to the continuous braided-fiber reinforced bushing. The non-MDA resin technology developed in this contract appears attractive for bushing applications that do not exceed a 300 C use temperature. Two thermoplastic polyimide resins were synthesized in order to generate injection molding compound powders. Excellent processing results were obtained at injection temperatures in excess of 300 C. Micro-tensile specimens were produced from each resin type and the Tg measurements (by TMA) for these samples were equivalent to AURUM(R). Thermal Gravimetric Analysis (TGA) conducted at 10 C/min showed that the non-MDA AMB-type polyimide thermoplastics had comparable weight loss to PMR-15 up to 500 C.
International Nuclear Information System (INIS)
Wunite depression located in the east of Erlian basin is one of the five biggest depressions in Erlian basin, and its sub-sags can be classified into two types: the units in depression zone and the other ones in uplift zone. Fluvial fan sedimentary-braided river system disposed at the former one, including vertical channel deposit model and centripetal channel deposit model: fan delta-lake system disposed at the later one, including fan deltas deposit model and braid river deltas deposit model. The main structure styles of sags are dustpan single-fault, composite single-fault, and composite double-fault. It is necessary to search these faults, in that the bottom slope belt of dustpan single-fault and composite single-fault is favorable for prospecting; the Saihantala sandstone which is at the two sides of the steep hill of composite single-fault and the sags of composite double-fault formed as monoclinal stratum. The sags featured by braid river deltas and vertical channel deposit model whose Saihantala sandstone possess modest thickness, fine stratification and connectivity, are favorable for prospecting in-situ sandstone-type Uranium deposit at Wunite zone. (authors)
An investigation to determine the producibility of a 3-D braider and bias direction weaving loom
Huey, Cecil O., Jr.
1991-01-01
The development of prototype machines for the production of generalized braid patterns is described. Mechanical operating principles and control strategies are presented for two prototype machines which were fabricated and evaluated. Both machines represent advances over current techniques for forming composite material preforms by enabling near ideal control of fiber orientation. Furthermore, they overcome both the lack of general control of produced fiber architectures and the complexity of other weaving processes that were produced for the same purpose. One prototype, the modified Farley braider, consists of an array of turntables which can be rotated 90 degrees and returned; hence, they can form tracks in the x and y axis. Yarn ends are transported about the surface formed by the turntables using motorized tractors. These tractors are controlled using an optical link with a control circuit and host computer. The tractors are powered through electrical contact with the turntables. The necessary relative motions are produced by a series of linear tractor moves combined with a sequence of turntable rotations. The movement of the tractors about the surface causes the yarns to produce the desired braiding pattern. The second device, the shuttle plate braider, consists of a braiding surface formed by an array of square elements, each separated from its neighbor by a gap. Beneath this surface lies a shuttle plate, which reciprocates first in one axis and then in the other. As this movement takes place, yarn carrying shuttles engage and disengage the plate by means of solenoid activated pins. By selective engagement and disengagement, the shuttles can move the yarn ends in any desired pattern, forming the desired braid. Control power, and control signals, are transmitted from the electronic interface circuit and host computer, via the braiding surface through electrical contact with the shuttles. Motive power is proved to the shuttles by motion of the shuttle plate
Evaluating the impact of a wide range of vegetation densities on river channel pattern
Pattison, Ian; Roucou, Ron
2016-04-01
Braided rivers are very dynamic systems which have complex controls over their planform and flow dynamics. Vegetation is one variable which influences channel geometry and pattern, through its effect on local flow hydraulics and the process continuum of sediment erosion-transport-deposition. Furthermore, where in the braided floodplain stable vegetation develops depends on the temporal sequencing of the river discharge i.e. floods. Understanding the effect of vegetation in these highly dynamic systems has multiple consequences for human activity and floodplain management. This paper focusses on the specific role of vegetation density in controlling braided river form and processes. Previous research in this field has been contradictory; with Gran and Paola (2001) finding that increasing vegetation density decreased the number of active channels. In contrast, Coulthard (2005] observed that as vegetation become denser there was an increase in the number of channels. This was hypothesized to be caused by flow separation around vegetation and the development of bars immediately downstream of the plant. This paper reports the results from a set of experiments in a 4m by 1m flume, where discharge, slope and sediment size were kept constant. Artificial grass was used to represent vegetation with a density ranging from 50 plants/m2 to 400 plants/m2. Digital photographs, using a GoPro camera with a fish eye lens, were taken from ~1m above the flume at an interval of 30 seconds during the 3 hour experiment. The experiments showed that as the vegetation density increased from 50 to 150 plants/m2, the number of channel bars developing doubled from 12 to 24. At vegetation densities greater than 150 plants/m2 there was a decline in the number of bars created to a minimum of 8 bars for a density of 400 plants/m2. We attribute these patterns to the effect that the vegetation has on flow hydraulics, sediment transport processes and the spatial patterns of erosion and deposition. We
Groundwater, biogeomorphic succession and controls on river channel pattern
Bätz, N.; Colombini, P.; Cherubini, P.; Lane, S. N.
2015-12-01
Strong feedbacks between river braiding and vegetation processes are now well-recognised. Recently, this has been illustrated in the notion of biogeomorphic succession, the transition from pioneer vegetation establishment to a fully-developed floodplain forest ecosystem. This succession also results in important vegetation-mediated feedbacks, through bank stabilisation and the capture of organic matter and fine sediments, stimulating soil formation and further enhancing the succession process itself. However, there are few studies that have addressed what this succession might mean for the evolution of channel planform, and almost no studies that have considered how this succession rates might be mediated by groundwater. The latter is a key concern for gravel-bed rivers with low water retention capacity. Here, we present results from a 2 km length of braiding-wandering river system in Switzerland (Allondon River). We show that the spatio-temporal dynamics of the groundwater table drives the biogeomorphic succession process at different rates, leading to very different river channel pattern responses. In the upper braiding-anastomosing part of the reach, the groundwater table is deeper. Here, dendrochronological data show that rates of pioneer vegetation growth are strongly dependent upon groundwater table fluctuations. Bank resistance modelling shows that vegetation-reinforcement of bank resistance is below its maximum. In the meandering lower part of the reach, with a mature floodplain forest, tree growth rates are independent of groundwater fluctuations, because trees can almost always access the higher groundwater table. Bank resistance is at its maximum. Through time, in response to disturbance frequency, the meandering tendency has migrated upstream. Thus, our results suggest that groundwater access modulates biogeomorphic succession processes in ways that determine the resultant river channel pattern.
Thomas, Michael F.; Nott, Jonathan; Price, David M.
2001-07-01
There is now a wide agreement that temperature depression in the humid tropics during the Last Glacial Maximum (LGM) was at least 5°C. Most estimates of precipitation reduction at the LGM range from 25-30% to 50-65%, based on proxy data, but the recent CCM1 model envisages only around 12%. Dates obtained from river sediments indicate major changes to fluvial activity in the late Quaternary. Isotope Zone 3 sediments (58-28 ka BP) are widespread and possibly indicate cooler conditions. Post-28 ka BP, and certainly post-21 ka BP, river regimes altered radically towards fan building, braiding or major reduction in all activity. This paper reports on fan formation in NE Queensland between 26 and 14 ka BP and reviews evidence for comparable changes in humid tropical areas of S America, W Africa and SE Asia, including records of Holocene sedimentation. Within a global rhythm of major changes to river regimes in the humid tropics during the late Quaternary, it is now possible to detect regional variations in stream response to climatic change. At the LGM, reductions in stream power may have led to fan formation in NE Queensland, while vegetation changes may have contributed to increased sediment loads and braiding in some forest marginal areas. But, in W Africa, greater aridity may have been responsible for enfeebled streams leaving few records. Channel cutting, then deposition of coarse sediment in braided rivers marked the transition to the early Holocene in W Africa, and fans became entrenched in NE Queensland. This regime persisted until forest recovery was complete by 9.5-8.5 ka BP, when widespread overbank deposition occurred and a change towards meandering channels took place widely across the humid tropical zone, followed by several cut-and-fill episodes in the middle and late Holocene.
Williams, Cory A.; Richards, Rodney J.; Schaffrath, Keelin R.
2015-01-01
Channel rehabilitation, or reconfiguration, to mitigate a variety of riverine problems has become a common practice in the western United States. However, additional work to monitor and assess the channel response to, and the effectiveness of, these modifications over longer periods of time (decadal or longer) is still needed. The Lake Fork of the Gunnison River has been an area of active channel modification to accommodate the needs of the Lake City community since the 1950s. The Lake Fork Valley Conservancy District began a planning process to assess restoration options for a reach of the Lake Fork in Lake City to enhance hydraulic and ecologic characteristics of the reach. Geomorphic channel form is affected by land-use changes within the basin and geologic controls within the reach. The historic channel was defined as a dynamic, braided channel with an active flood plain. This can result in a natural tendency for the channel to braid. A braided channel can affect channel stability of reconfigured reaches when a single-thread meandering channel is imposed on the stream. The U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board and Colorado River Water Conservation District, began a study in 2010 to quantify existing hydraulic and habitat conditions for a reach of the Lake Fork of the Gunnison River in Lake City, Colorado. The purpose of this report is to quantify existing Lake Fork hydraulic and habitat conditions and establish a baseline against which post-reconfiguration conditions can be compared. This report (1) quantifies the existing hydraulic and geomorphic conditions in a 1.1-kilometer section of the Lake Fork at Lake City that has been proposed as a location for future channel-rehabilitation efforts, (2) characterizes the habitat suitability of the reach for two trout species based on physical conditions within the stream, and (3) characterizes the current riparian canopy density.
Institute of Scientific and Technical Information of China (English)
ZHONG Jun-yi; ZHENG Jun-mao; WANG Guo-peng; LI Gui-lin; YU Gong-ming
2006-01-01
Tectonic movements in the North Slope of Biyang Depression are comparatively mild and stable, thus generating two categories of deltas. Elementary reasons for the coexistence of deltas are the existence of the palaeodrainage pattern and the effect of palaeotopography. The sedimentary facies is the most elementary factor controlling the physical property of reservoirs. The layout and spatial combination model of the sand body and faults are the major influential factors on the occurrence of hydrocarbons. Comparative study on Houzhang and Yanglou Braided Deltas as well as Zhangchang and Gucheng Meandering Deltas suggests that the hydrocarbons distribute primarily in the mouth bar subfacies and secondarily in the distal bar subfacies of the braided delta, while the oil-water and aqueous layers are mainly found in the subaquatic distributary channel. Although the sand body of the meandering delta has excellent stratification and high porosity, the thickness is far less than that of the braided delta. Therefore, the yield of hydrocarbon is relatively low. The mudstone of the delta front subfacies is a kind of source rock with a high content of organic matter. The conducting system for oil/gas migration in the North Slope is a composite one comprising faults and sandstone reservoirs. A large amount of oil/gas from the deep depression first migrated towards the slope along the sand body which stretches and connects with the source rocks, and then redistributed along the faults in the slope. After the movement reached a standstill, the faults formed the occlusion in the up-dip direction of the sand body, generating a great quantity of fault block hydrocarbon reservoirs in the North Slope.
Numerical simulation of morphodynamic diversity in the World's largest rivers
Nicholas, A.
2012-04-01
The World's largest rivers share many common properties, including gentle longitudinal bed gradients (~ 0.01-0.1 m per km), high mean annual discharges (~ >10,000 cumecs), and sand-sized bed sediment (D50 ~ 0.1-0.4 mm), yet despite these similarities they are characterised by diverse planform patterns and morphodynamic behaviour (including meandering, braided and anabranching river styles). Recent studies have shown that this diversity cannot be explained using existing channel pattern classification schemes that apply to small rivers. Indeed at present, the causes of morphodynamic diversity in the World's largest rivers remain unclear. Moreover, elucidation of process-form interactions in large rivers is hampered by logistical difficulties involved in field data collection, and by the time period over which satellite imagery is available, which is short given the slow rates of channel change in many large rivers. Numerical models provide a further possible approach for investigating large river morphodynamics. However, although many such models exist, they have generally been developed or applied to simulate either meandering or braided rivers, rather than to investigate a range of channel styles. This paper aims to address this shortcoming using a new numerical simulation model, which is applied to explore the controls on morphodynamic diversity in large sand-bed rivers. This model is based on the 2D shallow water equations with secondary circulation correction, with model components representing total sand transport, suspended transport of silt and clay, bank erosion, vegetation growth and floodplain development. Numerical simulations representing time periods of c. 200 years illustrate how a wide range of channel morphologies, including meandering, braided and anabranching channels, may develop from the same initial conditions and external forcing (valley gradient and discharge regime). These results shed light on the process controls on morphodynamic diversity
Directory of Open Access Journals (Sweden)
Bachuki Mesablishvili
2015-01-01
Full Text Available The definition of Azumaya algebras over commutative rings \\(R\\ requires the tensor product of modules over \\(R\\ and the twist map for the tensor product of any two \\(R\\-modules. Similar constructions are available in braided monoidal categories, and Azumaya algebras were defined in these settings. Here, we introduce Azumaya monads on any category \\(\\mathbb{A}\\ by considering a monad \\((F,m,e\\ on \\(\\mathbb{A}\\ endowed with a distributive law \\(\\lambda: FF\\to FF\\ satisfying the Yang–Baxter equation (BD%please define -law. This allows to introduce an opposite monad \\((F^\\lambda,m\\cdot \\lambda,e\\ and a monad structure on \\(FF^\\lambda\\. The quadruple \\((F,m,e,\\lambda\\ is called an Azumaya monad, provided that the canonical comparison functor induces an equivalence between the category \\(\\mathbb{A}\\ and the category of \\(FF^\\lambda\\-modules. Properties and characterizations of these monads are studied, in particular for the case when \\(F\\ allows for a right adjoint functor. Dual to Azumaya monads, we define Azumaya comonads and investigate the interplay between these notions. In braided categories (V\\(,\\otimes,I,\\tau\\, for any V-algebra \\(A\\, the braiding induces a BD-law \\(\\tau_{A,A}:A\\otimes A\\to A\\otimes A\\, and \\(A\\ is called left (right Azumaya, provided the monad \\(A\\otimes-\\ (resp. \\(-\\otimes A\\ is Azumaya. If \\(\\tau\\ is a symmetry or if the category V admits equalizers and coequalizers, the notions of left and right Azumaya algebras coincide.
Qualifications of Bonding Process of Temperature Sensors to Deep-Space Missions
Ramesham, Rajeshuni; Kitiyakara, Amarit; Redick, Richard W., III; Sunada, Eric T.
2011-01-01
A process has been examined for bonding a platinum resistance thermometer (PRT) onto potential aerospace materials such as flat aluminum surfaces and a flexible copper tube to simulate coaxial cables for flight applications. Primarily, PRTs were inserted into a silver-plated copper braid to avoid stresses on the sensor while the sensor was attached with the braid to the base material for long-duration, deep-space missions. A1-1145/graphite composite (planar substrate) and copper tube have been used in this study to assess the reliability of PRT bonding materials. A flexible copper tube was chosen to simulate the coaxial cable to attach PRTs. The substrate materials were cleaned with acetone wipes to remove oils and contaminants. Later, the surface was also cleaned with ethyl alcohol and was air-dried. The materials were gently abraded and then were cleaned again the same way as previously mentioned. Initially, shielded (silver plated copper braid) PRT (type X) test articles were fabricated and cleaned. The base antenna material was pretreated and shielded, and CV-2566 NuSil silicone was used to attach the shielded PRT to the base material. The test articles were cured at room temperature and humidity for seven days. The resistance of the PRTs was continuously monitored during the thermal cycling, and the test articles were inspected prior to, at various intermediate steps during, and at the end of the thermal cycling as well. All of the PRTs survived three times the expected mission life for the JUNO project. No adhesion problems were observed in the PRT sensor area, or under the shielded PRT. Furthermore, the PRT resistance accurately tracked the thermal cycling of the chamber.
Quantum groups: Geometry and applications
Energy Technology Data Exchange (ETDEWEB)
Chu, C.S. [Lawrence Berkeley Lab., CA (United States). Theoretical Physics Group
1996-05-13
The main theme of this thesis is a study of the geometry of quantum groups and quantum spaces, with the hope that they will be useful for the construction of quantum field theory with quantum group symmetry. The main tool used is the Faddeev-Reshetikhin-Takhtajan description of quantum groups. A few content-rich examples of quantum complex spaces with quantum group symmetry are treated in details. In chapter 1, the author reviews some of the basic concepts and notions for Hopf algebras and other background materials. In chapter 2, he studies the vector fields of quantum groups. A compact realization of these vector fields as pseudodifferential operators acting on the linear quantum spaces is given. In chapter 3, he describes the quantum sphere as a complex quantum manifold by means of a quantum stereographic projection. A covariant calculus is introduced. An interesting property of this calculus is the existence of a one-form realization of the exterior differential operator. The concept of a braided comodule is introduced and a braided algebra of quantum spheres is constructed. In chapter 4, the author considers the more general higher dimensional quantum complex projective spaces and the quantum Grassman manifolds. Differential calculus, integration and braiding can be introduced as in the one dimensional case. Finally, in chapter 5, he studies the framework of quantum principal bundle and construct the q-deformed Dirac monopole as a quantum principal bundle with a quantum sphere as the base and a U(1) with non-commutative calculus as the fiber. The first Chern class can be introduced and integrated to give the monopole charge.
Quantum groups: Geometry and applications
International Nuclear Information System (INIS)
The main theme of this thesis is a study of the geometry of quantum groups and quantum spaces, with the hope that they will be useful for the construction of quantum field theory with quantum group symmetry. The main tool used is the Faddeev-Reshetikhin-Takhtajan description of quantum groups. A few content-rich examples of quantum complex spaces with quantum group symmetry are treated in details. In chapter 1, the author reviews some of the basic concepts and notions for Hopf algebras and other background materials. In chapter 2, he studies the vector fields of quantum groups. A compact realization of these vector fields as pseudodifferential operators acting on the linear quantum spaces is given. In chapter 3, he describes the quantum sphere as a complex quantum manifold by means of a quantum stereographic projection. A covariant calculus is introduced. An interesting property of this calculus is the existence of a one-form realization of the exterior differential operator. The concept of a braided comodule is introduced and a braided algebra of quantum spheres is constructed. In chapter 4, the author considers the more general higher dimensional quantum complex projective spaces and the quantum Grassman manifolds. Differential calculus, integration and braiding can be introduced as in the one dimensional case. Finally, in chapter 5, he studies the framework of quantum principal bundle and construct the q-deformed Dirac monopole as a quantum principal bundle with a quantum sphere as the base and a U(1) with non-commutative calculus as the fiber. The first Chern class can be introduced and integrated to give the monopole charge
Development of Textile Reinforced Composites for Aircraft Structures
Dexter, H. Benson
1998-01-01
NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980's NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not cost-effective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight service with minimal damage. The cost and damage tolerance barriers of conventional laminated composites led NASA to focus on new concepts in composites which would incorporate the automated manufacturing methods of the textiles industry and which would incorporate through-the-thickness reinforcements. The NASA Advanced Composites Technology (ACT) Program provided the resources to extensively investigate the application of textile processes to next generation aircraft wing and fuselage structures. This paper discusses advanced textile material forms that have been developed, innovative machine concepts and key technology advancements required for future application of textile reinforced composites in commercial transport aircraft. Multiaxial warp knitting, triaxial braiding and through-the-thickness stitching are the three textile processes that have surfaced as the most promising for further development. Textile reinforced composite structural elements that have been developed in the NASA ACT Program are discussed. Included are braided fuselage frames and window-belt reinforcements, woven/stitched lower fuselage side panels, stitched multiaxial warp knit wing skins, and braided wing stiffeners. In addition, low-cost processing concepts such as resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM) are discussed. Process modeling concepts to predict resin flow and cure in textile preforms are also discussed.
Pizzuto, J.; Pitlick, J.
2007-12-01
We performed a series of laboratory flume experiments to document the adjustment of straight channels carved from non-cohesive sediment to overbank flows. We first created a stable channel adjusted to a bankfull discharge. Then, the discharge was abruptly increased to create an overbank flow. In all of our experiments, the channel widened during overbank flow until the increased discharge could be accommodated within the channel, suggesting that bank erosion in the absence of deposition will tend to eliminate flooding. We propose two dimensionless numbers to evaluate these processes in nature. The first, termed the Flood Elimination Number (FLENUM), represents the ratio of the duration of flooding to the time required for bank erosion to fully capture overbank flows during a single flood. The second, termed the Channel Stability Number (CHASNUM), evaluates the maximum length of channel that can accommodate the additional sediment supplied by widening without catastrophic deposition or changes in channel planform (such as braiding). Our experiments suggest that a critical value of the FLENUM is ~0.1. For FLENUM values higher than 0.1, rivers will accommodate flooding through channel widening, likely leading to braiding. As expected, braided rivers have high FLENUM values on the order of 10. Rivers with FLENUM values lower than 0.1 should endure overbank flows without significant widening, and indeed single-thread meandering rivers with cohesive banks have FLENUM values around 0.01. In our experiments, the CHASNUM was approximately 50 river widths, approximately equal to the working length of our experimental channel, which explains our ability to successfully maintain a stable, single thread channel despite extensive channel widening. The CHASNUM may provide an interesting explanation for the observation of periodically spaced disturbance zones in some gravel-bed rivers.
The cyclic fatigue behavior of a Nicalon/SiC composite
Energy Technology Data Exchange (ETDEWEB)
Miriyala, N.; Liaw, P.K.; McHargue, C.J. [Univ. of Tennessee, Knoxville, TN (United States); Snead, L.L. [Oak Ridge National Lab., TN (United States)
1996-10-01
Cyclic fatigue tests were performed at ambient temperature on a Nicalon/SiC composite to study the effects of fabric orientation on the mechanical behavior. Four-point bend specimens were loaded either parallel or normal to the braided fabric plies. The maximum stresses chosen during the fatigue tests were 60, 70, and 80% of the monotonic strengths, respectively, in both orientations. Specimen failure did not occur in any case even after one million loading cycles. However, it was observed that much of the decrease in the composite modulus occurred in the first few (<10) cycles, and the fabric orientation did not significantly affect the effective modulus or midspan deflection trends.
A Remark on CFT Realization of Quantum Doubles of Subfactors: Case Index { < 4}
Bischoff, Marcel
2016-03-01
It is well known that the quantum double {D(Nsubset M)} of a finite depth subfactor {Nsubset M}, or equivalently the Drinfeld center of the even part fusion category, is a unitary modular tensor category. It is big open conjecture that all (unitary) modular tensor categories arise from conformal field theory. We show that for every subfactor {Nsubset M} with index {[M:N] construct completely rational nets with the opposite braiding of {{SU(2)}_k} and use the well-known fact that all subfactors with index {[M:N] < 4} arise by {α}-induction from {{SU(2)}_k}.
The role of B B Kadomtsev's ideas in shaping the current understanding of turbulent transport
International Nuclear Information System (INIS)
B B Kadomtsev's turbulent diffusion models are reviewed. Some of the current approaches to describing 'long-range correlation' effects are presented that are directly based on B B Kadomtsev's ideas (diffusion renormalization of quasilinear equations, the percolation approach to strong turbulence, stochastic instability and the transverse diffusion of plasma particles as factors affecting transport in a 'braided' magnetic field). It is shown that B B Kadomtsev's analytical methods have great heuristic power and will undoubtedly influence the further development of turbulent transport theory. (from the history of physics)
A robust and well shielded thermal conductivity device for low temperature measurements.
Toews, W H; Hill, R W
2014-04-01
We present a compact mechanically robust thermal conductivity measurement apparatus for measurements at low temperatures (conductivity copper box is used to enclose the sample and all the components. The box provides protection for the thermometers, heater, and most importantly the sample increasing the portability of the mount. In addition to physical protection, the copper box is also effective at shielding radio frequency electromagnetic interference and thermal radiation, which is essential for low temperature measurements. A printed circuit board in conjunction with a braided ribbon cable is used to organize the delicate wiring and provide mechanical robustness.
Baez, J C; Baez, John C.; Langford, Laurel
1997-01-01
Just as links may be algebraically described as certain morphisms in the category of tangles, compact surfaces smoothly embedded in R^4 may be described as certain 2-morphisms in the 2-category of `2-tangles in 4 dimensions'. In this announcement we give a purely algebraic characterization of the 2-category of unframed unoriented 2-tangles in 4 dimensions as the `free semistrict braided monoidal 2-category with duals on one unframed self-dual object'. A forthcoming paper will contain a proof of this result using the movie moves of Carter, Rieger and Saito. We comment on how one might use this result to construct invariants of 2-tangles.
A topological model of composite preons
Bilson-Thompson, S O
2005-01-01
We present a modification of the preon model proposed independently by Shupe and Harari. A basic dynamics is developed by treating the binding of preons as topological in nature and identifying the substructure of quarks, leptons and gauge bosons with elements of the braid group B_3. Topological considerations and a straightforward set of assumptions lead directly to behaviour consistent with much of the known phenomenology of the Standard Model. The preons of this model may be viewed as composite in nature, and composed of sub-preons, representing exactly two levels of substructure within quarks and leptons.
Gibling, Martin; Ielpi, Alessandro; Bashforth, Arden; Davies, Neil
2015-04-01
Vegetation profoundly influences modern fluvial systems, depending on plant life-history strategies, tolerance to disturbance, and habitat drainage. However, direct evidence for these dynamic relationships is cryptic and has commonly been overlooked in ancient deposits. We report evidence for profound interactions between channels, in situ and transported vegetation in Lower Pennsylvanian formations of Atlantic Canada (~310 Ma), attributed to braided, meandering and fixed-channel (anastomosing) systems. Plant groups include lycopsids that preferred stable wetland settings, disturbance-tolerant calamitaleans, and deeply rooted cordaitaleans (early gymnosperms) that originated in the late Mississippian and colonised both wetland and dryland settings. For the meandering and anastomosing channel deposits, upright vegetation was observed within channel-based bedforms and bars and on channel margins. Lycopsids and calamitalean groves colonized the channel bed and bank-attached bars during periods of reduced flow, nucleating bar growth after flow resumed. Upright lycopsids and cordaitaleans are common along channel cutbanks and are locally tilted towards the channel, implying involvement in bank stabilization. Rhizoconcretions that formed around deep cordaitalean roots may have aided bank reinforcement. Tetrapod and arthropod trackways in the channel deposits indicate a close linkage between riparian and aquatic ecosystems. In the braided systems, sediments that contain abundant cordaitalean logs constitute nearly 20% of channel deposits, and the logs form channel-base lags, fill channels up to 6 m deep, and form nuclei for shallow sandbars. Log accumulations overlain by shale lenses imply a contribution to channel avulsion. Rooted channel-sandstones containing upright trees are interpreted as vegetated islands in an island-braided system. Anastomosing systems are abundant in these Lower Pennsylvanian formations but rare in older strata, and the multi-channel island-braided
Rădoane, Maria; Nechita, Constantin; Chiriloaei, Francisca; Rădoane, Nicolae; Popa, Ionel; Roibu, Cătălin; Robu, Delia
2015-06-01
The main objective of this paper is to describe the late Holocene behaviour of rivers using an interdisciplinary approach combining fluvial geomorphology and subfossil trunk dendrochronology. The subfossil wood material collected along the rivers was investigated for dendrometric and dendrochronologic parameters. The research methods in these fields helped us to understand the effect of the fluvial environment on riparian trees and their records and helped in reconstructing the riparian palaeoenvironment. The study area consists of two rivers with different typologies but comparable sizes: the Moldova River, which features a braided to wandering channel in its lower reach, and the Siret River, which features a sinuous-meandering channel. Along the 100-km-long floodplain of the former and the 144-km-long floodplain of the latter, we found and sampled 77 subfossil trunks, of which 26 were subjected to 14C dating. The resulting data consist of floodplain facies mapping data, electric resistivity measurements, absolute dates, and dendrometric and dendrochronologic data. The results indicate that during a 100-year period, the two rivers were sensitive to climate change and anthropogenic effects, particularly a narrowing of the active channel by 76% in the braided channel and 38% in the sinuous-meandering channel. During the past 3300-3000 YBP, the Moldova River maintained its braided style, whereas the sinuous-meandering style has been characteristic of the Siret River for the previous 6800-4600 YBP. The two distinct fluvial environments are recorded in the dendrometric structure of the trunks buried in the channel-fill sediments. The braided fluvial environment was more effective in uprooting riparian trees and incorporating them in the floodplain deposits, whereas the sinuous-meandering style of stream effectively buried tree trunks in lateral accretion lobes. Absolute and dendrochronologic dating allowed for the reconstruction of timelines of the felling of the trees
Understanding middle school math cool problems to get students thinking and connecting
Hyde, Arthur; Heck, Cheryl
2009-01-01
In Understanding Middle School Math, Arthur Hyde gathers 50 cool problems that lead to deep thinking. Problems such as Chocolate Algebra, where students discover linear relationships among the pocket money needed for differently priced chocolate candies. With the latest research and decades of classroom experience, he braids language, cognition, and math to create problems that connect math to the real world, to students' lives, and to prior knowledge. Extensively field-tested problems that scaffold content and processes, and give students multiple entry points into learning.
Energy Technology Data Exchange (ETDEWEB)
Kargarian, Mehdi, E-mail: kargarian@physics.utexas.edu [Department of Physics, The University of Texas at Austin, Austin, TX 78712 (United States)
2012-10-15
The anyonic excitations of topological two-body color code model are used to implement a set of gates. Because of two-body interactions, the model can be simulated in optical lattices. The excitations have nontrivial mutual statistics, and are coupled to nontrivial gauge fields. The underlying lattice structure provides various opportunities for encoding the states of a logical qubit in anyonic states. The interactions make the transition between different anyonic states, so being logical operation in the computational bases of the encoded qubit. Two-qubit gates can be performed in a topological way using the braiding of anyons around each other.
Finite element analysis of the stiffness of fabric reinforced composites
Foye, R. L.
1992-01-01
The objective of this work is the prediction of all three dimensional elastic moduli of textile fabric reinforced composites. The analysis is general enough for use with complex reinforcing geometries and capable of subsequent improvements. It places no restrictions on fabric microgeometry except that the unit cell be determinate and rectangular. The unit cell is divided into rectangular subcells in which the reinforcing geometries are easier to define and analyze. The analysis, based on inhomogeneous finite elements, is applied to a variety of weave, braid, and knit reinforced composites. Some of these predictions are correlated to test data.
Dynamics of Crowd Behaviors: From Complex Plane to Quantum Random Fields
Ivancevic, Vladimir G.; Reid, Darryn J.
2015-11-01
The following sections are included: * Complex Plane Dynamics of Crowds and Groups * Introduction * Complex-Valued Dynamics of Crowd and Group Behaviors * Kähler Geometry of Crowd and Group Dynamics * Computer Simulations of Crowds and Croups Dynamics * Braids of Agents' Behaviors in the Complex Plane * Hilbert-Space Control of Crowds and Groups Dynamics * Quantum Random Fields: A Unique Framework for Simulation, Optimization, Control and Learning * Introduction * Adaptive Quantum Oscillator * Optimization and Learning on Banach and Hilbert Spaces * Appendix * Complex-Valued Image Processing * Linear Integral Equations * Riemann-Liouville Fractional Calculus * Rigorous Geometric Quantization * Supervised Machine-Learning Methods * First-Order Logic and Quantum Random Fields
The Changing Fate of Cloth Shoes
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
ONE day I found by chance one of my old photos taken 30 years ago. In it I was still a serious 17-year-old girl with my hair in two short braids and dressed in a blue cloth coat, brown corduroys and a pair of black cloth shoes each fastened by a strap at the side My eyes fixed on the shoes and lingered for quite a long time. A smile quietly crawled over my lips. Isn't it the fashionable "little girl's shoe" which is expected to prevail in the market this year?
Packing solutions for power plants
International Nuclear Information System (INIS)
Asbestos packings are being replaced in more and more countries with alternative products. This paper discusses modern packing solutions for valves and pumps in power plants. Die-moulded packing rings made of expanded graphite foil are described m detail, with recommendations for correct installation. Application examples for spring-loaded valves and cover lid seals are given. As an alternative for repair and service use, a braided expanded graphite packing reinforced with Inconel wire is described. Proposals for sealing various pump applications in power plants are also made. (Author)
Chu, Robert L.; Bayha, Tom D.; Davis, HU; Ingram, J. ED; Shukla, Jay G.
1992-01-01
Composite Wing and Fuselage Structural Design/Manufacturing Concepts have been developed and evaluated. Trade studies were performed to determine how well the concepts satisfy the program goals of 25 percent cost savings, 40 percent weight savings with aircraft resizing, and 50 percent part count reduction as compared to the aluminum Lockheed L-1011 baseline. The concepts developed using emerging technologies such as large scale resin transfer molding (RTM), automatic tow placed (ATP), braiding, out-of-autoclave and automated manufacturing processes for both thermoset and thermoplastic materials were evaluated for possible application in the design concepts. Trade studies were used to determine which concepts carry into the detailed design development subtask.
Textile Technologies and Tissue Engineering: A Path Toward Organ Weaving.
Akbari, Mohsen; Tamayol, Ali; Bagherifard, Sara; Serex, Ludovic; Mostafalu, Pooria; Faramarzi, Negar; Mohammadi, Mohammad Hossein; Khademhosseini, Ali
2016-04-01
Textile technologies have recently attracted great attention as potential biofabrication tools for engineering tissue constructs. Using current textile technologies, fibrous structures can be designed and engineered to attain the required properties that are demanded by different tissue engineering applications. Several key parameters such as physiochemical characteristics of fibers, microarchitecture, and mechanical properties of the fabrics play important roles in the effective use of textile technologies in tissue engineering. This review summarizes the current advances in the manufacturing of biofunctional fibers. Different textile methods such as knitting, weaving, and braiding are discussed and their current applications in tissue engineering are highlighted. PMID:26924450
Single-thread channels resulting from a localization process driven by vegetation
Narteau, C.; Tal, M.
2009-12-01
The unpredictable manner in which braided rivers evolve is in stark contrast to the orderly migration pattern of meandering rivers driven by erosion along outer bends and deposition along inner banks. Braided channels are the default pattern that develops when an unbounded water flow interacts with noncohesive sediment. A series of laboratory experiments demonstrated that plants alone are able to achieve the two key mechanisms to developing meandering: slowing the rate of widening and discouraging channel cutoffs. Plants initially colonized braid-bars that were emergent during low flow. By adding cohesion to the sediment and increasing roughness, vegetation deterred the flow from reoccupying areas which were colonized. By decreasing erosion rates, plants made it possible for deposition along the inner bank to match the rate of erosion along the outer bank. This enabled the channel to develop sinuosity and migrate laterally while suppressing channel splitting and the creation of new channel width. Areas with established vegetation provided stable conditions which promoted new seedling establishment and expansion of the vegetated area. A generic mechanism of width production in the braided state is the opportunistic creation of new channels. As existing flow paths become slightly less favorable, for example by bar deposition or an increase in sinuosity, new ones are readily created in areas that are not currently occupied by flow. By making it more difficult for flow to occupy vegetated areas, plants in effect decouple the transition between wet and dry areas, making it harder for areas that are dry (vegetated) to turn wet (reoccupied by flow) and less likely for areas that are wet to become dry. The net effect is localization of the flow into a single-thread channel with transitions between wet and dry occurring predominantly along the channel margin and driving lateral migration while a single-thread channel remains intact. We are using a 1D cellular automata model
Ho, Choon-Lin; Hosotani, Yutaka
Starting from the quantum field theory of nonrelativistic matter on a torus interacting with Chern-Simons gauge fields, we derive the Schrödinger equation for an anyon system. The nonintegrable phases of the Wilson line integrals on a torus play an essential role. In addition to generating degenerate vacua, they enter in the definition of a many-body Schrödinger wave function in quantum mechanics, which can be defined as a regular function of the coordinates of anyons. It obeys a non-Abelian representation of the braid group algebra, being related to Einarsson’s wave function by a singular gauge transformation.
Practical and ornamental knots
Shaw, George Russell
2008-01-01
For centuries, everyone from sailors, fishermen, and cowboys to explorers, hunters, and mountaineers have known about - and relied on - the indispensable knot. Many of them also knew that the diversity of knot crafting was limited only by the imagination. In this classic guide, George Russell Shaw reveals the unlimited potential of the knot as not only a basic tool, but as a beautiful work of art.Filled with easy-to-follow and accurate instructions on creating scores of useful and decorative knots, 193 hand-drawn illustrations will guide you in creating: Braids Angler Knots Japanese Knots L
Acromioclavicular Joint Reconstruction.
Scillia, Anthony J; Cain, E Lyle
2015-12-01
Our technique for acromioclavicular joint reconstruction provides a variation on coracoclavicular ligament reconstruction to also include acromioclavicular ligament reconstruction. An oblique acromial tunnel is drilled, and the medial limb of the gracilis graft, after being crossed and passed beneath the coracoid and through the clavicle, is passed through this acromial tunnel and sutured to the trapezoid graft limb after appropriate tensioning. Tenodesis screws are not placed in the bone tunnels to avoid graft fraying, and initial forces on the graft are offloaded with braided absorbable sutures passed around the clavicle. PMID:27284528
Topological gravity with exchange algebra
Aoyama, S.
1993-01-01
A topological gravity is obtained by twisting the effective $(2,0)$ super\\-gravity. We show that this topological gravity has an infinite number of BRST invariant quantities with conformal weight $0$. They are a tower of OSp$(2,2)$ multiplets and satisfy the classical exchange algebra of OSp$(2,2)$. We argue that these BRST invariant quantities become physical operators in the quantum theory and their correlation functions are braided according to the quantum OSp$(2,2)$ group. These propertie...
Hui, David; Sun, C. T.
The present conference discusses the parametric design of composite ducts and pressure vessels, enhanced material damping through the use of thermoelasticity, a performance simulation of structural composite rods, a stress analysis of anisotropic laminated circular cylindrical shells, the stresses in rotating (orthotropic, circular) composite disks and plates, and the effects of wear tip behavior on particulate composites. Also treated are a model for compression failure in fiber composite laminates, the effect of fiber interaction on matrix and interfacial microcracking in ceramic matrix composites, the dynamic response of an external circular crack to normal stresses in a transversely isotropic material, and the pinned joint behavior of laminated holes reinforced with braided composite.
Elm, Jessica H L; Lewis, Jordan P; Walters, Karina L; Self, Jen M
2016-01-01
American Indian and Alaska Native sexual minority (two-spirit) women are vulnerable to substance misuse and mental health challenges due to multiple minority oppressed status and exposure to stress and trauma. Yet, these women find pathways toward healing and wellness. We conducted a qualitative data analysis of interviews derived from a national health study and gained an understanding of 11 two-spirit women's resilience and recovery patterns. Emergent from the data, a braided resiliency framework was developed which elucidates multilayered abilities, processes, and resources involved in their resiliency. We recommend that resilience-promoting strategies be incorporated into substance misuse and mental health interventions. PMID:27254761
Embeddings of a strange attractor into R3.
Tsankov, Tsvetelin D; Nishtala, Arunasri; Gilmore, Robert
2004-05-01
The algorithm for determining a global Poincaré section is applied to a previously studied dynamical system on R2 x S1 and a one-parameter family of embeddings of the strange attractor it generates into R3. We find that the topological properties of the attractor are embedding dependent to a limited extent. These embeddings rigidly preserve mechanism, which is a simple stretch and fold. The embeddings studied show three discrete topological degrees of freedom: parity, global torsion, and braid type of the genus-one torus bounding the embedded attractor. PMID:15244912
Textile technology development
Shah, Bharat M.
1995-01-01
The objectives of this report were to evaluate and select resin systems for Resin Transfer Molding (RTM) and Powder Towpreg Material, to develop and evaluate advanced textile processes by comparing 2-D and 3-D braiding for fuselage frame applications and develop window belt and side panel structural design concepts, to evaluate textile material properties, and to develop low cost manufacturing and tooling processes for the automated manufacturing of fuselage primary structures. This research was in support of the NASA and Langley Research Center (LaRc) Advanced Composite Structural Concepts and Materials Technologies for Primary Aircraft Structures program.
Parabolic Deligne-Lusztig varieties
Digne, François
2011-01-01
Motivated by the Brou\\'e conjecture on blocks with abelian defect groups for finite reductive groups, we study "parabolic" Deligne-Lusztig varieties and construct on those which occur in the Brou\\'e conjecture an action of a braid monoid, whose action on their $\\ell$-adic cohomology will conjecturally factor trough a cyclotomic Hecke algebra. In order to construct this action, we need to enlarge the set of varieties we consider to varieties attached to a "ribbon category"; this category is a {\\em Garside category}, which plays an important role in our proof, so we devote the first part of our paper to the necessary background on Garside categories.
A Middle-Upper Miocene fluvial-lacustrine rift sequence in the Song Ba Rift, Vietnam
DEFF Research Database (Denmark)
Lars H., Nielsen; Henrik I., Petersen; Nguyen D., Dau;
2007-01-01
The small Neogene Krong Pa graben is situated within the continental Song Ba Rift, which is bounded by strike-slip faults that were reactivated as extensional faults in Middle Miocene time. The 500 m thick graben-fill shows an overall depositional development reflecting the structural evolution...... as carrier beds, whereas the braided fluvial sandstones and conglomerates along the graben margins may form reservoirs. The Krong Pa graben thus contains oil-prone lacustrine source rocks, effective conduits for generated hydrocarbons and reservoir sandstones side-sealed by the graben faults toward...