Topology optimization of structures with geometrical nonlinearities
Gea, Hae Chang
Topology optimization of structures with geometrical nonlinearities Hae Chang Gea *, Jianhui Luo structures. Ó 2001 Published by Elsevier Science Ltd. Keywords: Topology optimization; Geometrical by Neves et al. [18], and the design of compliant mechanisms using topology optimization has also been
Optimizing the geometrical accuracy of curvilinear meshes
Toulorge, Thomas; Remacle, Jean-François
2015-01-01
This paper presents a method to generate valid high order meshes with optimized geometrical accuracy. The high order meshing procedure starts with a linear mesh, that is subsequently curved without taking care of the validity of the high order elements. An optimization procedure is then used to both untangle invalid elements and optimize the geometrical accuracy of the mesh. Standard measures of the distance between curves are considered to evaluate the geometrical accuracy in planar two-dimensional meshes, but they prove computationally too costly for optimization purposes. A fast estimate of the geometrical accuracy, based on Taylor expansions of the curves, is introduced. An unconstrained optimization procedure based on this estimate is shown to yield significant improvements in the geometrical accuracy of high order meshes, as measured by the standard Haudorff distance between the geometrical model and the mesh. Several examples illustrate the beneficial impact of this method on CFD solutions, with a part...
Water Resource System Optimization by Geometric Programming
Meier, W. L.; Shih, C. S.; Wray, D. J.
1971-01-01
water resources optimization problems. This new and potentially powerful technique is called geometric programming. It is one of a class of mathematical programming techniques. Mathematical programming discussed extensively elsewhere [56,23] refers to a...
Optimization of biotechnological systems through geometric programming
Marin-Sanguino, Alberto; Voit, Eberhard O; Gonzalez-Alcon, Carlos; Torres, Nestor V
2007-01-01
Background In the past, tasks of model based yield optimization in metabolic engineering were either approached with stoichiometric models or with structured nonlinear models such as S-systems or linear-logarithmic representations. These models stand out among most others, because they allow the optimization task to be converted into a linear program, for which efficient solution methods are widely available. For pathway models not in one of these formats, an Indirect Optimization Method (IOM) was developed where the original model is sequentially represented as an S-system model, optimized in this format with linear programming methods, reinterpreted in the initial model form, and further optimized as necessary. Results A new method is proposed for this task. We show here that the model format of a Generalized Mass Action (GMA) system may be optimized very efficiently with techniques of geometric programming. We briefly review the basics of GMA systems and of geometric programming, demonstrate how the latter may be applied to the former, and illustrate the combined method with a didactic problem and two examples based on models of real systems. The first is a relatively small yet representative model of the anaerobic fermentation pathway in S. cerevisiae, while the second describes the dynamics of the tryptophan operon in E. coli. Both models have previously been used for benchmarking purposes, thus facilitating comparisons with the proposed new method. In these comparisons, the geometric programming method was found to be equal or better than the earlier methods in terms of successful identification of optima and efficiency. Conclusion GMA systems are of importance, because they contain stoichiometric, mass action and S-systems as special cases, along with many other models. Furthermore, it was previously shown that algebraic equivalence transformations of variables are sufficient to convert virtually any types of dynamical models into the GMA form. Thus, efficient methods for optimizing GMA systems have multifold appeal. PMID:17897440
Ligand Binding to the Pregnane X Receptor by Geometric Matching of Hydrogen Bonds
Kettner, Lutz
Ligand Binding to the Pregnane X Receptor by Geometric Matching of Hydrogen Bonds Robert; Ryan Watkins x 1 Introduction Hydrogen bonds are important in proteinligand interactions. We describe a geometric model of hydrogen bonds, which we use to study ligand binding to the Pregnane X Receptor (PXR
A geometric representation scheme suitable for shape optimization
NASA Technical Reports Server (NTRS)
Tortorelli, Daniel A.
1990-01-01
A geometric representation scheme is outlined which utilizes the natural design variable concept. A base configuration with distinct topological features is created. This configuration is then deformed to define components with similar topology but different geometry. The values of the deforming loads are the geometric entities used in the shape representation. The representation can be used for all geometric design studies; it is demonstrated here for structural optimization. This technique can be used in parametric design studies, where the system response is defined as functions of geometric entities. It can also be used in shape optimization, where the geometric entities of an original design are modified to maximize performance and satisfy constraints. Two example problems are provided. A cantilever beam is elongated to meet new design specifications and then optimized to reduce volume and satisfy stress constraints. A similar optimization problem is presented for an automobile crankshaft section. The finite element method is used to perform the analyses.
Herschlag, Dan
Testing Geometrical Discrimination within an Enzyme Active Site: Constrained Hydrogen Bonding May 26, 2008; E-mail: herschla@stanford.edu Abstract: Enzymes are classically proposed to accelerate scale on which enzymes can distinguish structural rearrangement, and the energetic significance
Improved bond-orbital calculations of rotation barriers and geometrical isomerism
NASA Astrophysics Data System (ADS)
Musso, Gian Franco; Magnasco, Valerio
Rotational barriers in 19 molecules possessing a single internal rotation angle around a B-N, C-C, C-N, C-O, N-N, N-O, O-O central bond and geometrical isomerism in 3 molecules possessing a N=N double bond have been studied ab initio by the improved bond-orbital method. The first approximation, where the chemical groups occurring in these molecules are described in terms of non-orthogonal SCF bond-orbitals constructed from energy-optimized bond hybrids and polarities, is improved in second order of perturbation theory by admitting single excitations from bonding to antibonding orbitals and accounting for induction including exchange (polarization and delocalization). The molecules studied possess 16 to 34 electrons and a variety of functional groups differing in their chemical structure (CH3, NH2, OH, NO, CHO, CH=CH2, NH= and some of their F-derivatives). The overall results obtained using a STO-3G basis, rigid rotation and experimental geometries, are close to experiment and to the corresponding MO-SCF calculations in the same basis, but individual energy components allow us to establish a clear correlation between barriers and chemical structure, grouping the 22 molecules into 4 classes. In the first class (CH3-X molecules and 1,2-difluoroethane) barriers are dominated by steric interactions (Pauli repulsions) which are sufficiently well described in first order. In the second class (N2H4, NH2OH, NH=NH and its fluoroderivatives, molecules all possessing lone pairs adjacent to the central bond) barriers are due to competition between first-order Pauli repulsion and characteristic geminal ?-?* delocalization occurring in second order. In the third class (1,3-butadiene, glyoxal, formamide and formic acid, molecules possessing double bonds and/or ?-lone pairs at both ends of the rotation axis) barriers are dominated by large ?-?* vicinal delocalization. In the fourth class (HNO2, H2O2 and its fluoroderivatives, molecules presenting both previous structural features) barriers result from competition between all preceding effects.
Alternative adhesive strategies to optimize bonding to radicular dentin.
Bouillaguet, Serge; Bertossa, Bruno; Krejci, Ivo; Wataha, John C; Tay, Franklin R; Pashley, David H
2007-10-01
This study tested the hypothesis that bond strengths of filling materials to radicular dentin might be optimized by using an indirect dentin bonding procedure with an acrylic core material. Roots of human teeth were endodontically prepared and obturated with EndoREZ, Epiphany, or the bonding of an acrylic point with SE Bond by using a direct or an indirect bonding technique. Bond strengths of endodontic sealers to radicular dentin were measured with a thin slice push-out test. Push-out strengths of EndoREZ and Epiphany to radicular dentin were less than 5 megapascals (MPa). The direct bonding technique with acrylic points and the self-etching adhesive had push-out strengths of 10 MPa, increasing to 18 MPa with the indirect technique. The use of the indirect bonding protocol with an acrylic point to compensate for polymerization stresses appears to be a viable means for optimizing bond strengths of endodontic filling materials to radicular dentin. PMID:17889695
NASA Technical Reports Server (NTRS)
Nelson, R. M.; Buratti, B. J.; Wallis, B. D.; Smythe, W. D.; Horn, L. J.
1990-01-01
The spectral geometric albedo and the bolometric Bond albedo of Triton are calculated using data from the Voyager spacecraft photopolarimeter and science experiments. The geometric albedo is not inconsistent with the presence of a weak absorption feature in Triton's spectrum near 0.75 micron. The bolometric Bond albedo (0.65) is consistent with the 38 K daytime surface temperature of Triton. The results are also in agreement with the 37.5 K temperature of nitrogen at an infrared basal pressure of 14 microbar.
Valence bond liquids and solids in geometrically frustrated magnets
NASA Astrophysics Data System (ADS)
Tchernyshyov, Oleg
2003-03-01
Frustrated magnets are models of strongly interacting systems. Frustration reveals itself through a vast degeneracy of the classical ground state and is responsible for a large number of soft modes that destroy spin order. Possible alternative phases that could emerge in place of the Néel state are: (a) The valence-bond solid (VBS), in which bond averages < Si ot Sj >, rather than spins themselves, form a periodic structure. (b) The valence-bond liquid (VBL), in which any bond order is absent, but there is hidden topological order, similar to that in the fractional quantum Hall effect. In recent years particular attention has been paid to the Heisenberg antiferromagnet on the pyrochlore lattice---a 3D network of corner-sharing tetrahedra---and its 2D analogs. It has been established that a spin-lattice coupling stabilizes the VBS in the pyrochlores (Yamashita and Ueda, Tchernyshyov et al.); the related spin-Peierls phase transition has been observed in ZnCr_2O4 (S.-H. Lee et al.). Fouet et al. have found numerically that quantum spins (S=1/2) on the checkerboard lattice form a VBS. Until recently, systematic approaches---such as the 1/S and 1/N expansions---to the problem of the ground state in the pyrochlore have met with little success: the remaining degeneracy in the first nontrivial order is still very large. New technical developments (Henley) have allowed us to construct explicitly all ground states at order 1/S and characterize the resulting phases for two pyrochlore-like lattices. We find a VBS---resembling that of Fouet et al.---on the checkerboard lattice and a VBL in a 2D pyrochlore slab. A study of the 3D pyrochlore is in progress.
Optimal Control of Underactuated Mechanical Systems: A Geometric Approach
L. Colombo; D. Martin de Diego; M. Zuccalli
2009-12-10
In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.
Technology Transfer Automated Retrieval System (TEKTRAN)
Dietary fatty acid type alters atherosclerotic lesion progression and macrophage lipid accumulation. Incompletely elucidated are the mechanisms by which fatty acids differing in double-bond geometric or positional configuration alter arterial lipid accumulation. The objective of this study was to ev...
Comparison between first geometric-arithmetic index and atom-bond connectivity index
NASA Astrophysics Data System (ADS)
Das, Kinkar Ch.; Trinajsti?, N.
2010-09-01
The first geometric-arithmetic index ( GA) [1] and atom-bond connectivity index ( ABC) [2] that are recently introduced, are found to be useful tools in QSPR and QSAR studies. In this letter we compare the GA and ABC indices for chemical trees and molecular graphs. Moreover, we also compare these two indices for general graphs.
A Discrete Geometric Optimal Control Framework for Systems with Symmetries
Marsden, Jerrold
model of an air vehicle flying through a digital terrain elevation map, and point out someA Discrete Geometric Optimal Control Framework for Systems with Symmetries Marin Kobilarov USC include autonomous vehicles such as unmanned helicopters, micro-air vehicles or underwater gliders. A
Geometric Parameterization and Multiobjective Shape Optimization of Convective Periodic Channels
E. Nobile; F. Pinto; G. Rizzetto
2006-01-01
In this article we describe a general procedure for the geometric parameterization and multiobjective shape optimization of periodic wavy channels, representative of the repeating module of an ample variety of heat exchangers. The two objectives considered are the maximization of heat transfer rate and the minimization of friction factor. Since there is no single optimum to be found, we use
Geometric optical optimization of the corneal lens of Notonecta glauca.
Horváth, G
1989-08-01
The optimal shape of the corneal lens of the water bug backswimmer (Notonecta glauca) and the optimal shape and position of the thin transition layer between the distal and proximal units of its cornea are theoretically determined. Using a geometric optical method, first the shape of a geometric interface between the lens units is determined, which eliminates the longitudinal spherical aberration. This interface is investigated for differently formed thick lenses when the medium in contact with the entrance surface of the lens is water or air. The optimal transition layer for the amphibious backswimmer is that, the boundaries of which are the theoretical interfaces for water and air, and the refractive index varies continuously in it. The optimal shape of the corneal lens is determined, with the disadvantageous lenses, with respect to the possible minimal spherical aberration and amount of reflected light from the transition layer, being rejected. The optimal position of the transition layer in the cornea can be obtained from the minimization of the amount of diffracted light on the marginal connection of the layers. The optimal corneal lens for backswimmer has ellipsoid boundary surfaces; the optimal transition layer in it is thin bell-shaped, at the marginal connection of which there is no dimple, the maximum of the layer is on the margin of the cornea. The shape of the theoretically optimal corneal lens, the shape and position of the theoretically optimal transition layer agree well with those of Notonecta glauca. The question posed, the geometric optical method used and the results presented are of general importance, and not only with respect to vision in the bug Notonecta, but also in the fossil trilobites, or in the wave guide theories which have been employed in similar modelling problems, in design of system of lenses without spherical aberration, for example. PMID:2615380
Wolfgang Kabsch; Christian Sander
1983-01-01
For a successful analysis of the relation between amino acid sequence and protein structure, an unambiguous and physically meaningful definition of secondary structure is essential. We have developed a set of simple and physically motivated criteria for secondary structure, programmed as a pattern-recognition process of hydrogen-bonded and geometrical features extracted from x-ray coordinates. Cooperative secondary structure is recognized as repeats
Self-optimized resonating-valence-bond trial wavefunctions
NASA Astrophysics Data System (ADS)
Beach, Kevin; Sandvik, Anders
2007-03-01
The spin singlet ground state of a quantum antiferromagnet can be expanded in the overcomplete basis of valence bond states. [1] To first approximation, the weight associated with each configuration is factorizable into a product of individual bond amplitudes. For nonfrustrated antiferromagnets with local interactions, mean field calculations indicate that the amplitudes are generically powerlaw in the bond length with exponent d+1, where d is the dimension of the lattice. Such states can be employed as the initial trial state for a valence bond projector calculation of the exact ground state. [2] Moreover, the amplitudes can be determined self- consistently by measuring the statistics of the bonds appear in the projected state and feeding this information back into the trial state. It is also possible to build some of the neglected bond-bond correlations into the trial state itself. The next level of approximation is to factorize the weights in terms of amplitudes that depend on the lengths and orientations of two valence bonds. Again, these amplitudes can be self-optimized in a simulation by matching them to the bond-- bond correlations of the projected state. [1] K. S. D. Beach and A. W. Sandvik, Nucl. Phys. B 750, 142 (2006).[2] A. W. Sandvik, Phys. Rev. Lett. 95, 207203 (2005).
Printability Optimization For Fine Pitch Solder Bonding
Kwon, Sang-Hyun; Lee, Chang-Woo; Yoo, Sehoon
2011-01-17
Effect of metal mask and pad design on solder printability was evaluated by DOE in this study. The process parameters were stencil thickness, squeegee angle, squeegee speed, mask separating speed, and pad angle of PCB. The main process parameters for printability were stencil thickness and squeegee angle. The response surface showed that maximum printability of 1005 chip was achieved at the stencil thickness of 0.12 mm while the maximum printability of 0603 and 0402 chip was obtained at the stencil thickness of 0.05 mm. The bonding strength of the MLCC chips was also directly related with the printability.
On the Distance to Optimality of the Geometric Approximate Minimum-Energy Attitude Filter
Trumpf, Jochen
On the Distance to Optimality of the Geometric Approximate Minimum-Energy Attitude Filter Mohammad-optimality of the recent geometric approximate minimum-energy (GAME) filter, an attitude filter for estimation on the rotation group SO(3). The GAME filter approximates the minimum-energy (optimal) filtering solution
Sigala, Paul A; Kraut, Daniel A; Caaveiro, Jose M M; Pybus, Brandon; Ruben, Eliza A; Ringe, Dagmar; Petsko, Gregory A; Herschlag, Daniel
2008-10-15
Enzymes are classically proposed to accelerate reactions by binding substrates within active-site environments that are structurally preorganized to optimize binding interactions with reaction transition states rather than ground states. This is a remarkably formidable task considering the limited 0.1-1 A scale of most substrate rearrangements. The flexibility of active-site functional groups along the coordinate of substrate rearrangement, the distance scale on which enzymes can distinguish structural rearrangement, and the energetic significance of discrimination on that scale remain open questions that are fundamental to a basic physical understanding of enzyme active sites and catalysis. We bring together 1.2-1.5 A resolution X-ray crystallography, (1)H and (19)F NMR spectroscopy, quantum mechanical calculations, and transition-state analogue binding measurements to test the distance scale on which noncovalent forces can constrain the structural relaxation or translation of side chains and ligands along a specific coordinate and the energetic consequences of such geometric constraints within the active site of bacterial ketosteroid isomerase (KSI). Our results strongly suggest that packing and binding interactions within the KSI active site can constrain local side-chain reorientation and prevent hydrogen bond shortening by 0.1 A or less. Further, this constraint has substantial energetic effects on ligand binding and stabilization of negative charge within the oxyanion hole. These results provide evidence that subtle geometric effects, indistinguishable in most X-ray crystallographic structures, can have significant energetic consequences and highlight the importance of using synergistic experimental approaches to dissect enzyme function. PMID:18808119
SDBD Plasma Actuator and Geometric Optimization for Optimal Flow Control of Wind Turbine Blades
NASA Astrophysics Data System (ADS)
Corke, Thomas; Williams, Theodore; Jemcov, Aleksandar; Cooney, John
2013-11-01
A Quantitative Design Optimization approach for active flow control using SDBD plasma actuators is presented. The approach couples passive geometric changes and plasma actuator design to produce a ``compliant flow'' that maximizes control authority. Aerodynamic shape optimization tools employed in this study make use of the adjoint formulation of the Navier-Stokes equations for incompressible flows. These are solved to obtain shape derivatives that are used in a gradient optimization procedure to produce aerodynamic shapes that are flow-control compliant. Coupling of compliant geometries and flow control devices are able to provide dynamic lift control to wind turbine blades. The effect of the plasma actuator is included as a body force distribution in the flow governing equations. The optimization seeks designs that effectively utilize a SDBD plasma actuator and are aerodynamically compliant to realize increased energy production on wind turbine blades.
Wikfeldt, K. T., E-mail: wikfeldt@hi.is [Science Institute, University of Iceland, Nordita, Stockholm, Sweden and University College London, London WC1E 6BT (United Kingdom); Michaelides, A. [Thomas Young Centre, London Centre for Nanotechnology and Department of Chemistry, University College London, London WC1E 6BT (United Kingdom)] [Thomas Young Centre, London Centre for Nanotechnology and Department of Chemistry, University College London, London WC1E 6BT (United Kingdom)
2014-01-28
Ab initio simulations that account for nuclear quantum effects have been used to examine the order-disorder transition in squaric acid, a prototypical H-bonded antiferroelectric crystal. Our simulations reproduce the >100 K difference in transition temperature observed upon deuteration as well as the strong geometrical isotope effect observed on intermolecular separations within the crystal. We find that collective transfer of protons along the H-bonding chains – facilitated by quantum mechanical tunneling – is critical to the order-disorder transition and the geometrical isotope effect. This sheds light on the origin of isotope effects and the importance of tunneling in squaric acid which likely extends to other H-bonded ferroelectrics.
NASA Astrophysics Data System (ADS)
Wikfeldt, K. T.; Michaelides, A.
2014-01-01
Ab initio simulations that account for nuclear quantum effects have been used to examine the order-disorder transition in squaric acid, a prototypical H-bonded antiferroelectric crystal. Our simulations reproduce the >100 K difference in transition temperature observed upon deuteration as well as the strong geometrical isotope effect observed on intermolecular separations within the crystal. We find that collective transfer of protons along the H-bonding chains - facilitated by quantum mechanical tunneling - is critical to the order-disorder transition and the geometrical isotope effect. This sheds light on the origin of isotope effects and the importance of tunneling in squaric acid which likely extends to other H-bonded ferroelectrics.
ResourceConstrained Geometric Network Optimization (Extended abstract)
Arkin, Estie
Joseph S. B. Mitchell y Giri Narasimhan z December 4, 1997 Abstract We study a variety of geometric Machines, Hughes Aircraft, and Sun Microsystems. z giri@msci.memphis.edu; http://www.msci.memphis.edu/~giri
ResourceConstrained Geometric Network Optimization (Extended abstract)
Narasimhan, Giri
Joseph S. B. Mitchell y Giri Narasimhan z December 18, 1997 Abstract We study a variety of geometric Machines, Hughes Aircraft, and Sun Microsystems. z giri@msci.memphis.edu; http://www.msci.memphis.edu/~giri
Multi-objective Optimization of Geometric Dimensions and Material Composition of
Vel, Senthil
optimization of a metal/metal functionally graded material active cooling component. The plane stress transient]), CP973, Multiscale andFunctionally GradedMaterials 2006 edited by G. H. Paulino, M.-J. Pmdera, R. HMulti-objective Optimization of Geometric Dimensions and Material Composition of Functionally
GEOMETRIC CHARACTERIZATION AND OPTIMIZATION OF 3D ORGANIC FLEXIBLE SOLAR CELLS
Kassegne, Samuel Kinde
GEOMETRIC CHARACTERIZATION AND OPTIMIZATION OF 3D ORGANIC FLEXIBLE SOLAR CELLS Characterization and Optimization of 3D Organic Flexible Solar Cells by Ashish K. Gaikwad Master of Science of flexible organic solar cells, micro-fabricated using novel microfabrication procedures. A fully functional
Optimization of absorption placement using geometrical acoustic models and least squares.
Saksela, Kai; Botts, Jonathan; Savioja, Lauri
2015-04-01
Given a geometrical model of a space, the problem of optimally placing absorption in a space to match a desired impulse response is in general nonlinear. This has led some to use costly optimization procedures. This letter reformulates absorption assignment as a constrained linear least-squares problem. Regularized solutions result in direct distribution of absorption in the room and can accommodate multiple frequency bands, multiple sources and receivers, and constraints on geometrical placement of absorption. The method is demonstrated using a beam tracing model, resulting in the optimal absorption placement on the walls and ceiling of a classroom. PMID:25920877
Elsevier Science 1 Front-to back-side overlay optimization after wafer bonding for
Technische Universiteit Delft
Elsevier Science 1 Front- to back-side overlay optimization after wafer bonding for 3D integration; accepted date here Abstract Wafer bonding consists in transferring the device to a new substrate, flipping a technique that makes possible to qualify the wafer bonding in order to know and realize the best achievable
NASA Astrophysics Data System (ADS)
Limbach, Hans-Heinrich; Pietrzak, Mariusz; Benedict, Hans; Tolstoy, Peter M.; Golubev, Nikolai S.; Denisov, Gleb S.
2004-11-01
In this paper, empirical corrections for anharmonic ground-state vibrations of hydrogen and deuterium in the hydrogen bridges A-L⋯B, L=H, D are introduced into the geometric hydrogen bond correlation analysis based on the empirical Pauling valence bond orders. The method is verified using the examples of the hydrogen bonded anions in [(CO) 5Cr-C?N⋯H⋯N?C-Cr(CO) 5] - As(Ph) 4+ ( 1h), in [(CO) 5Cr-C?N⋯H⋯N?C-Cr(CO) 5] - N( n-propyl) 4+ ( 2h), in the model system [C?N⋯H⋯N?C] - Li + ( 3h), and their deuterated isotopologs ( 1d, 2d and 3d) studied previously by dipolar NMR and theoretical methods by H. Benedict et al. [J. Am. Chem. Soc. 120 (1998) 2939]. The new corrections are able to describe isotope effects on hydrogen bond geometries from the weak to the strong hydrogen bond regime, taking into account single and double-well situations.
Junghyun Kwon; Kyoung Mu Lee; Frank C. Park
2009-01-01
We propose a geometric method for visual tracking, in which the 2-D affine motion of a given object template is estimated in a video sequence by means of coordinate-invariant particle filtering on the 2-D affine group Aff(2). Tracking performance is further enhanced through a geometrically defined optimal importance function, obtained explicitly via Taylor expansion of a principal component analysis based
Benchmark case studies in optimization of geometrically nonlinear structures
A. Suleman; R. Sedaghati
2005-01-01
A structural optimization algorithm is developed for truss and beam structures undergoing large deflections against instability. The method combines the nonlinear buckling analysis using the displacement control technique, with the optimality criteria approaches. Several benchmark case studies illustrate the procedure and the results are compared with examples reported in the literature. It is shown that a design based on the
Inertial Geometric Particle Swarm Optimization Alberto Moraglio and Julian Togelius
Togelius, Julian
form of traditional particle swarm optimization (PSO) without the inertia term that applies naturally GPSO (IGPSO), that generalizes the traditional PSO endowed with the full equation of motion Particle Swarm Optimization (PSO) is a relatively recently devised popualtion-based stochastic global
NASA Technical Reports Server (NTRS)
Horowitz, Stephen; Chen, Tai-An; Chandrasekaran, Venkataraman; Tedjojuwono, Ken; Cattafesta, Louis; Nishida, Toshikazu; Sheplak, Mark
2004-01-01
This paper presents a geometric Moir optical-based floating-element shear stress sensor for wind tunnel turbulence measurements. The sensor was fabricated using an aligned wafer-bond/thin-back process producing optical gratings on the backside of a floating element and on the top surface of the support wafer. Measured results indicate a static sensitivity of 0.26 microns/Pa, a resonant frequency of 1.7 kHz, and a noise floor of 6.2 mPa/(square root)Hz.
Optimization of the geometrical stability in square ring laser gyroscopes
Santagata, R; Belfi, J; Beverini, N; Cuccato, D; Di Virgilio, A; Ortolan, A; Porzio, A; Solimeno, S
2014-01-01
Ultra sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth: the project name is GINGER (Gyroscopes IN GEneral Relativity), a ground-based triaxial array of ring lasers aiming at measuring the Earth rotation rate with an accuracy of 10^-14 rad/s. Such ambitious goal is now within reach as large area ring lasers are very close to the necessary sensitivity and stability. However, demanding constraints on the geometrical stability of the laser optical path inside the ring cavity are required. Thus we have started a detailed study of the geometry of an optical cavity, in order to find a control strategy for its geometry which could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions which allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical s...
Optimization of the geometrical stability in square ring laser gyroscopes
NASA Astrophysics Data System (ADS)
Santagata, R.; Beghi, A.; Belfi, J.; Beverini, N.; Cuccato, D.; Di Virgilio, A.; Ortolan, A.; Porzio, A.; Solimeno, S.
2015-03-01
Ultra-sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth. Our project for this goal is called GINGER (gyroscopes in general relativity), and consists of a ground-based triaxial array of ring lasers aimed at measuring the rotation rate of the Earth with an accuracy of {{10}-14} rad {{s}-1}. Such an ambitious goal is now within reach, as large-area ring lasers are very close to the required sensitivity and stability. However, demanding constraints on the geometrical stability of the optical path of the laser inside the ring cavity are required. Thus, we have begun a detailed study of the geometry of an optical cavity in order to find a control strategy for its geometry that could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions that allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical stability of a square cavity strongly increases by implementing a suitable system to measure the mirror distances, and that the geometry stabilization can be achieved by measuring the absolute lengths of the two diagonals and the perimeter of the ring.
Optimization of the geometrical stability in square ring laser gyroscopes
R. Santagata; A. Beghi; J. Belfi; N. Beverini; D. Cuccato; A. Di Virgilio; A. Ortolan; A. Porzio; S. Solimeno
2014-11-12
Ultra sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth: the project name is GINGER (Gyroscopes IN GEneral Relativity), a ground-based triaxial array of ring lasers aiming at measuring the Earth rotation rate with an accuracy of 10^-14 rad/s. Such ambitious goal is now within reach as large area ring lasers are very close to the necessary sensitivity and stability. However, demanding constraints on the geometrical stability of the laser optical path inside the ring cavity are required. Thus we have started a detailed study of the geometry of an optical cavity, in order to find a control strategy for its geometry which could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions which allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical stability of a square cavity strongly increases by implementing a suitable system to measure the mirror distances, and that the geometry stabilization can be achieved by measuring the absolute lengths of the two diagonals and the perimeter of the ring.
Geometric optimal design of MR damper considering damping force, control energy and time constant
NASA Astrophysics Data System (ADS)
Nguyen, Q. H.; Choi, S. B.; Kim, K. S.
2009-02-01
This paper presents an optimal design of magnetorheological (MR) damper based on finite element analysis. The MR damper is constrained in a specific volume and the optimization problem identifies geometric dimensions of the damper that minimizes an objective function. The objective function is proposed by considering the damping force, dynamic range and the inductive time constant of the damper. After describing the configuration of the MR damper, a quasi-static modelling of the damper is performed based on Bingham model of MR fluid. The initial geometric dimensions of the damper are then determined based on the assumption of constant magnetic flux density throughout the magnetic circuit of the damper. Subsequently, the optimal design variables that minimize the objective function are determined using a golden-section algorithm and a local quadratic fitting technique via commercial finite element method parametric design language. A comparative work on damping force and time constant between the initial and optimal design is undertaken.
Junghyun Kwon; Kyoung Mu Lee; Frank Chongwoo Park
2009-01-01
We propose a geometric method for visual tracking, in which the 2-D affine motion of a given object template is estimated in a video sequence by means of coordinate- invariant particle filtering on the 2-D affine group Aff(2). Tracking performance is further enhanced through a geo- metrically defined optimal importance function, obtained explicitly via Taylor expansion of a principal component
Fluence Map Optimization in IMRT Cancer Treatment Planning and A Geometric Approach
Zhang, Yin
therapy (IMRT) is a state-of-the-art technique for administering radiation to cancer patients. The goal radiation therapy, Optimal treatment planning, Fluence map op- timization, A geometric Approach eventually recover. Therefore, research in radiation therapy seeks methods of delivering a sufficient dose
Geometric Algorithms for Optimal Airspace Design and Air Traffic Controller Workload Balancing
Mitchell, Joseph S.B.
engineers and air transportation policy makers are continually "tweaking" the system to adjust for changes Airspace System (NAS) is a complex transportation system designed to facilitate the management of airGeometric Algorithms for Optimal Airspace Design and Air Traffic Controller Workload Balancing
Optimization of 3D Shape Sharpening Filter Based on Geometric Statistical Values
Tokyo, University of
Optimization of 3D Shape Sharpening Filter Based on Geometric Statistical Values Masanari Yokomizo, by applying a sharpening filter to the 3D shape data of a plaster statue, highlighted contours compa- rable is to prepare a stone statue that is used as a reference and to sharpen the input data to match the histogram
Joining of Silicon Carbide: Diffusion Bond Optimization and Characterization
NASA Technical Reports Server (NTRS)
Halbig, Michael C.; Singh, Mrityunjay
2008-01-01
Joining and integration methods are critically needed as enabling technologies for the full utilization of advanced ceramic components in aerospace and aeronautics applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. In the application, several SiC substrates with different hole patterns to form fuel and combustion air channels are bonded to form the injector. Diffusion bonding is a joining approach that offers uniform bonds with high temperature capability, chemical stability, and high strength. Diffusion bonding was investigated with the aid of titanium foils and coatings as the interlayer between SiC substrates to aid bonding. The influence of such variables as interlayer type, interlayer thickness, substrate finish, and processing time were investigated. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.
... is a procedure that uses a tooth-colored composite resin (plastic) to repair a tooth. Bonding can ... cleaned regularly by a dental hygienist. Risks The composite resin used in bonding isn't nearly as ...
Effects of geometric nonlinearities on the response of optimized box beam structures
NASA Technical Reports Server (NTRS)
Ragon, S.; Gurdal, Z.
1993-01-01
The present minimum-mass designs for a two-spar rectangular box beam were derived on the basis of linear-buckling FEM analysis constraints. In order to ascertain the effects of any geometric nonlinearities on these designs, each was subjected to a geometrically nonlinear FEM analysis. In all cases, the structure collapses below the design load, and does so in a mode which differs from that of linear theory. This discrepancy is attributable to such nonlinear panel-interaction mechanisms as rib-crusing loads. The optimized design is highly sensitive to crushing loads, relative to the nonoptimal design.
Extraordinary magnetoresistance in two and three dimensions: Geometrical optimization
NASA Astrophysics Data System (ADS)
Pugsley, Lisa M.; Ram-Mohan, L. R.; Solin, S. A.
2013-02-01
The extraordinary magnetoresistance (EMR) in metal-semiconductor hybrid structures was first demonstrated using a van der Pauw configuration for a circular semiconductor wafer with a concentric metallic inclusion in it. This effect depends on the orbital motion of carriers in an external magnetic field, and the remarkably high magnetoresistance response observed suggests that the geometry of the metallic inclusion can be optimized to further significantly enhance the EMR. Here, we consider the theory and simulations to achieve this goal by comparing both two-dimensional (2D) and three-dimensional (3D) structures in an external magnetic field to evaluate the EMR in them. New results for 3D structures are presented to show the feasibility of such modeling. Examples of structures that are compatible with present day technological capabilities are given together with their expected responses in terms of EMR. For a 10 ?m 2D square structure with a square metallic inclusion, we find an MR up to 107 percent for an applied magnetic field of 1 T. In 3D, for a 10 ?m cube with a 5 ?m centered metallic inclusion, we obtain an MR of ˜104 percent, which is comparable with the 2D structure of equivalent dimensions. The results presented here for specific geometries are scalable to smaller dimensions down to the onset of ballistic effects in the transport. The present calculations open up the possibility of 3D magnetic field sensors capable of determining the magnitude and also direction of the magnetic field once a full characterization of the sensor response is performed.
Annicchiarico, W
2001-01-01
Structural optimization is an engineering field which deal with the improvement of existing solutions or even more find new solutions that are better than the previous ones under some selected criterion. Shape optimization is a research area in this field and it is involved in developing new methodologies to find better structural design based on the shape as resistant element, as for example solutions with the less stress concentration zones and made with the minimum amount of material. The goal of this doctoral dissertation is to present and discuss a general structural shape optimization methodology able to optimize several structural systems or mechanical devices. The approach presented herein is based on global search optimization tools such as Genetic Algorithms and geometric design elements by means of beta-splines curves and surfaces representation. Finally the great versatility of the developed tool is presented and discussed with an application example. PMID:11899717
Using Bonding to Guide Transition State Optimization Adam B. Birkholz and H. Bernhard Schlegel*
Schlegel, H. Bernhard
Using Bonding to Guide Transition State Optimization Adam B. Birkholz and H. Bernhard Schlegel* Optimization of a transition state typically requires both a good initial guess of the molecular structure and one or more computationally demanding Hessian calculations to converge reliably. Often, the transition
Parametric Study and Optimal Design in Wire Bonding Process for Mini Stack-Die Package
Hsiang-Chen Hsu; Shen-Wen Yu; Yu-Teng Hsu; Wei-Yaw Chang; Ming-Jer Lin; Ruei-Ming Lin; Pei-Chieh Chin; Hung-Chun Ho; Ming-Cheng Lu; Cheng-Tung Lee; Chin-Liang Chen; Chien-Hung Liao; Yu-Jung Huang; Shen-Li Fu; Li-Shan Chen
2006-01-01
The purpose of this research is to study the parametric factors of wire bonding and optimal design rules for 4-layer mini stack-die package. This paper demonstrates the characteristic of low loop height, fine bond pad pitch and long overhead staggered chip in mini SD package. The loop height is limited to 3.5mil, the diameter of gold wire is 0.8 mil
Optimization of the Geometric Phase Sensitivity of an Array of Atom Ring Interferometers
NASA Astrophysics Data System (ADS)
Sandoval-Sanchez, Karina; Campo, Christian; Rivera, Tabitha; Toland, John
2015-05-01
Sagnac, and Aharonov-Bohm phase shifts are important geometric phase shifts in atom interferometry. These phase shifts characterize rotational and magnetic field interference effects respectively. Theoretical explorations have shown that a series of ring interferometers can be connected in series to increase the sensitivity of the overall device while keeping the maximum path separation less than the coherence length of the atoms. It has also been shown that the application of an area chirp to the rings will further enhance the sensitivity of the array of rings to geometric phase shifts. Area chirp refers to characterizing all of the rings in the array to a fixed percentage of a reference ring, this allows for the phase shifts in each ring to be characterized by one ring. The goal of this project is to determine a set of parameters namely kL, the product of the ring circumference and the wave number and ?, the chirp factor for the area chirp, that optimize the geometric phase sensitivity for an array of N rings. We model the transmission coefficient of a quantum matter wave through an area chirped array of interferometers as a function of phase, using transfer matrices to represent the transmission and reflection of individual rings in the array. Isolated transmission resonances represent the domain of interest, these are regions of high phase sensitivity. After optimizing a ring array without loss we apply velocity broadening to the input matter waves to investigate a more realistic output.
Witte, Marnix G.; Geer, Joris van der; Schneider, Christoph; Lebesque, Joos V.; Alber, Markus; Herk, Marcel van [Department of Radiation Oncology, Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); Sektion fuer Biomedizinische Physik, Universitaetsklinik fuer Radioonkologie, Universitaet Tuebingen (Germany); Department of Radiation Oncology, Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands)
2007-09-15
The purpose of this work was the development of a probabilistic planning method with biological cost functions that does not require the definition of margins. Geometrical uncertainties were integrated in tumor control probability (TCP) and normal tissue complication probability (NTCP) objective functions for inverse planning. For efficiency reasons random errors were included by blurring the dose distribution and systematic errors by shifting structures with respect to the dose. Treatment plans were made for 19 prostate patients following four inverse strategies: Conformal with homogeneous dose to the planning target volume (PTV), a simultaneous integrated boost using a second PTV, optimization using TCP and NTCP functions together with a PTV, and probabilistic TCP and NTCP optimization for the clinical target volume without PTV. The resulting plans were evaluated by independent Monte Carlo simulation of many possible treatment histories including geometrical uncertainties. The results showed that the probabilistic optimization technique reduced the rectal wall volume receiving high dose, while at the same time increasing the dose to the clinical target volume. Without sacrificing the expected local control rate, the expected rectum toxicity could be reduced by 50% relative to the boost technique. The improvement over the conformal technique was larger yet. The margin based biological technique led to toxicity in between the boost and probabilistic techniques, but its control rates were very variable and relatively low. During evaluations, the sensitivity of the local control probability to variations in biological parameters appeared similar for all four strategies. The sensitivity to variations of the geometrical error distributions was strongest for the probabilistic technique. It is concluded that probabilistic optimization based on tumor control probability and normal tissue complication probability is feasible. It results in robust prostate treatment plans with an improved balance between local control and rectum toxicity, compared to conventional techniques.
NASA Astrophysics Data System (ADS)
Paul, Bijan Kumar; Guchhait, Nikhil
2013-02-01
Density functional theory based computational study has been performed to characterize intramolecular hydrogen bonding (IMHB) interaction in a series of salicylic acid derivatives varying in chlorine substitution on the benzene ring. The molecular systems studied are salicylic acid, 5-chlorosalicylic acid, 3,5-dichlorosalicylic acid and 3,5,6-tricholorosalicylic acid. Major emphasis is rendered on the analysis of IMHB interaction by calculation of electron density ?(r) and Laplacian ?2?(r) at the bond critical point using atoms-in-molecule theory. Topological features, energy densities based on ?(r) through perturbing the intramolecular H-bond distances suggest that at equilibrium geometry the IMHB interaction develops certain characteristics typical of covalent interaction. The interplay between aromaticity and resonance-assisted hydrogen bonding (RAHB) is discussed using both geometrical and magnetic criteria as the descriptors of aromaticity. The optimized geometry features, molecular electrostatic potential map analysis are also found to produce a consensus view in relation with the formation of RAHB in these systems.
NASA Astrophysics Data System (ADS)
Nguyen, Q. H.; Lang, V. T.; Nguyen, N. D.; Choi, S. B.
2014-01-01
When designing a magneto-rheological brake (MRB), it is well known that the shape of the brake envelope significantly affects the performance characteristics of the brake. In this study, different shapes for the MR brake envelope, such as rectangular, polygonal or spline shape, are considered and the most suitable shape identified. MRBs with different envelope shapes are introduced followed by the derivation of the braking torque based on Bingham-plastic behavior of the magneto-rheological fluid (MRF). Optimization of the design of the MRB with different envelope shapes is then done. The optimization problem is to find the optimal value for the significant geometric dimensions of the MRB that can produce a certain required braking torque while the brake mass is minimized. A finite element analysis integrated with an optimization tool is employed to obtain optimal solutions for the MRBs. From the results, the most suitable shape for the brake envelope is identified and discussed with the reduction of mass. In addition, the results of the analysis are compared with the experimental results to verify the proposed optimal design characteristics.
Implementation and Optimization of miniGMG - a Compact Geometric Multigrid Benchmark
Williams, Samuel; Kalamkar, Dhiraj; Singh, Amik; Deshpande, Anand M.; Straalen, Brian Van; Smelyanskiy, Mikhail; Almgren, Ann; Dubey, Pradeep; Shalf, John; Oliker, Leonid
2012-12-01
Multigrid methods are widely used to accelerate the convergence of iterative solvers for linear systems used in a number of different application areas. In this report, we describe miniGMG, our compact geometric multigrid benchmark designed to proxy the multigrid solves found in AMR applications. We explore optimization techniques for geometric multigrid on existing and emerging multicore systems including the Opteron-based Cray XE6, Intel Sandy Bridge and Nehalem-based Infiniband clusters, as well as manycore-based architectures including NVIDIA's Fermi and Kepler GPUs and Intel's Knights Corner (KNC) co-processor. This report examines a variety of novel techniques including communication-aggregation, threaded wavefront-based DRAM communication-avoiding, dynamic threading decisions, SIMDization, and fusion of operators. We quantify performance through each phase of the V-cycle for both single-node and distributed-memory experiments and provide detailed analysis for each class of optimization. Results show our optimizations yield significant speedups across a variety of subdomain sizes while simultaneously demonstrating the potential of multi- and manycore processors to dramatically accelerate single-node performance. However, our analysis also indicates that improvements in networks and communication will be essential to reap the potential of manycore processors in large-scale multigrid calculations.
Topology optimization of geometrically nonlinear structures including thermo-mechanical coupling
NASA Astrophysics Data System (ADS)
Pajot, Joseph M.
The goal of this research is to develop an efficient and robust methodology for the topology optimization of geometrically nonlinear structures actuated by thermal expansion. The corotational finite element method is used to model the geometric nonlinearity because its element independent nature and linear elastic element core provide a flexibility to introduce thermal loads and formulate analytical sensitivities for any element type. To create thermal expansion, this work uses both prescribed temperature changes and localized heat generation via Joule heating, where electrical and thermal conduction are additionally considered. In this coupled multi-physics problem, emphasis is put on material models and coupling to maintain accuracy and efficiency. One-way coupling is shown to be equivalent to a small strain assumption, and the proper modeling of convection properties in topology optimization is addressed. To model the thermal and electrical conduction in planar layered materials, an averaged (smeared) model based on the smoothed properties of the individual layers is introduced. Large displacement structures are prone to exhibit buckling and limit point behavior. To include instabilities in topology optimization, specialized techniques are introduced to overcome inherent numerical difficulties. A nodal density transformation is introduced to isolate structurally relevant eigenmodes, and a homotopy between linear and nonlinear finite elements is provided to limit the effects of mesh distortion. The proposed methodology is successfully applied to micro-mechanism applications capable of a three-dimensional range of motion, including novel designs reflective of the manufacturing technology used in the micro-electro-mechanical (MEMS) community.
NASA Astrophysics Data System (ADS)
Ahmed, Asm Sabbir; Capello, Kevin; Chiang, Albert; Cardenas-Mendez, Erick; Kramer, Gary H.
2009-11-01
This paper describes the optimization of the geometric parameters of a Marinelli beaker to maximize the detection efficiency of sample measurement with a High Purity Germanium (HPGe) detector. A Monte Carlo model was developed and the detector pulse spectrum was studied for different beaker geometries with an HPGe detector. The results show that good sample measurement with an HPGe detector can be obtained by appropriate selection of the sample height over the top of the detector cap and the beaker radius surrounding the detector. Optimum sample heights and beaker radii are recommended for different sample volumes for a given detector specification.
NASA Astrophysics Data System (ADS)
Mignani, A. G.; Ciaccheri, L.; Giannelli, L.; Mencaglia, A. A.
2012-03-01
An experimental study was carried out, aimed at optimizing the optical/geometrical configuration for measuring the concentration of biological cells by means of static light scattering measurements. A LED-based optoelectronic setup making use of optical fibers was experimented, as the precursor of a low-cost device to be integrated in instrumentation for cytometry. Two biological sample types were considered as test samples of the most popular analyses - cervical cells and urine, respectively. The most suitable wavelengths and detecting angles were identified, and calibration curves were calculated.
Yoo, S. J. Ben
Design Optimization of Energy-Efficient Hydrophobic Wafer-bonded III-V/Si Semiconductor Optical on hydrophobic wafer bonding based on Ar/O2 plasma has shown that current injection is possible through the Si active devices on silicon [4, 5]. However, there have been few reports describing the optimal hydrophobic
Coogan, Sean C P; Raubenheimer, David; Stenhouse, Gordon B; Nielsen, Scott E
2014-01-01
Nutrient balance is a strong determinant of animal fitness and demography. It is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. These relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. Here we apply geometric models to understand how the nutritional compositions of foods available to an omnivorous member of the order Carnivora, the grizzly bear (Ursus arctos L.), relate to optimal macronutrient intake, and assess the seasonal nutritional constraints on the study population in west-central Alberta, Canada. The models examined the proportion of macronutrients that bears could consume by mixing their diet from food available in each season, and assessed the extent to which bears could consume the ratio of protein to non-protein energy previously demonstrated using captive bears to optimize mass gain. We found that non-selective feeding on ungulate carcasses provided a non-optimal macronutrient balance with surplus protein relative to fat and carbohydrate, reflecting adaptation to an omnivorous lifestyle, and that optimization through feeding selectively on different tissues of ungulate carcasses is unlikely. Bears were, however, able to dilute protein intake to an optimal ratio by mixing their otherwise high-protein diet with carbohydrate-rich fruit. Some individual food items were close to optimally balanced in protein to non-protein energy (e.g. Hedysarum alpinum roots), which may help explain their dietary prevalence. Ants may be consumed particularly as a source of lipids. Overall, our analysis showed that most food available to bears in the study area were high in protein relative to lipid or carbohydrate, suggesting the lack of non-protein energy limits the fitness (e.g. body size and reproduction) and population density of grizzly bears in this ecosystem. PMID:24841821
Riemannian geometric approach to human arm dynamics, movement optimization, and invariance
NASA Astrophysics Data System (ADS)
Biess, Armin; Flash, Tamar; Liebermann, Dario G.
2011-03-01
We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparametrized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm’s configuration space may provide insights into the emerging properties of the movements generated by the motor system.
Soft chelating irrigation protocol optimizes bonding quality of Resilon/Epiphany root fillings.
De-Deus, Gustavo; Namen, Fátima; Galan, João; Zehnder, Matthias
2008-06-01
This study was designed to test the impact of either a strong (MTAD) or a soft (1-hydroxyethylidene-1, 1-bisphosphonate [HEPB]) chelating solution on the bond strength of Resilon/Epiphany root fillings. Both 17% EDTA and the omission of a chelator in the irrigation protocol were used as reference treatments. Forty extracted human upper lateral incisors were prepared using different irrigation protocols (n = 10): G1: NaOCl, G2: NaOCl + 17% EDTA, G3: NaOCl + BioPure MTAD (Dentsply/Tulsa, Tulsa, OK), and G4: NaOCl + 18% HEPB. The teeth were obturated and then prepared for micropush-out assessment using root slices of 1 mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey multiple comparisons were used to compare the results among the experimental groups. EDTA- and MTAD-treated samples revealed intermediate bond strength (0.3-3.6 MPa). The lowest bond strengths were achieved in NaOCl-treated samples (0.3-1.2 MPa, p < 0.05). The highest bond strength was reached in the HEBP-treated samples (3.1-6.1 MPa, p < 0.05). Under the present in vitro conditions, the soft chelating irrigation protocol (18% HEBP) optimized the bonding quality of Resilon/Epiphany (Resilon Research LLC, Madison, CT) root fillings. PMID:18498893
Geometric Construction of Eighth-Order Optimal Families of Ostrowski's Method
Motsa, S. S.
2015-01-01
Based on well-known fourth-order Ostrowski's method, we proposed many new interesting optimal families of eighth-order multipoint methods without memory for obtaining simple roots. Its geometric construction consists in approximating f n? at zn in such a way that its average with the known tangent slopes f n? at xn and yn is the same as the known weighted average of secant slopes and then we apply weight function approach. The adaptation of this strategy increases the convergence order of Ostrowski's method from four to eight and its efficiency index from 1.587 to 1.682. Finally, a number of numerical examples are also proposed to illustrate their accuracy by comparing them with the new existing optimal eighth-order methods available in the literature. It is found that they are very useful in high precision computations. Further, it is also noted that larger basins of attraction belong to our methods although the other methods are slow and have darker basins while some of the methods are too sensitive upon the choice of the initial value. PMID:25884035
A geometrical optimization of a magneto-rheological rotary brake in a prosthetic knee
NASA Astrophysics Data System (ADS)
Gudmundsson, K. H.; Jonsdottir, F.; Thorsteinsson, F.
2010-03-01
Magneto-rheological (MR) fluids have been successfully introduced to prosthetic devices. One such device is a biomechanical prosthetic knee that uses MR fluids to actively control its rotary stiffness. The brake is rotational, utilizing the MR fluid in shear mode. In this study, the geometrical design of the MR brake is addressed. This includes the design of the magnetic circuit and the geometry of the fluid chamber. Mathematical models are presented that describe the rotary torque of the brake. A novel perfluorinated polyether (PFPE)-based MR fluid is introduced, whose properties are tailored for the prosthetic knee. On-state and off-state rheological measurements of the MR fluid are presented. The finite element method is used to evaluate the magnetic flux density in the MR fluid. The design is formulated as an optimization problem, aiming to maximize the braking torque. A parametric study is carried out for several design parameters. Subsequently, a multi-objective optimization problem is defined that considers three design objectives: the field-induced braking torque, the off-state rotary stiffness and the weight of the brake. Trade-offs between the three design objectives are investigated which provides a basis for informed design decisions on furthering the success of the MR prosthetic knee.
Geometric optimization of an active magnetic regenerative refrigerator via second-law analysis
NASA Astrophysics Data System (ADS)
Li, Peng; Gong, Maoqiong; Wu, Jianfeng
2008-11-01
Previous analyses [Z. Yan and J. Chen, J. Appl. Phys. 72, 1 (1992); J. Chen and Z. Yan, ibid., 84, 1791 (1998); Lin et al., Physica B 344, 147 (2004); Yang et al., ibid., 364, 33 (2005); Xia et al., ibid., 381, 246 (2006).] of irreversibilities in magnetic refrigerators overlooked several important losses that could be dominant in a real active magnetic regenerative refrigerator (AMRR). No quantitative expressions have been provided yet to estimate the corresponding entropy generations in real AMRRs. The important geometric parameters of AMRRs, such as the aspect ratio of the active magnetic regenerator and the refrigerant diameter, are still arbitrarily chosen. Expressions for calculating different types of entropy generations in the AMRR were derived and used to optimize the aspect ratio and the refrigerant diameter. An optimal coefficient of performance (15.54) was achieved at an aspect ratio of 6.39 and a refrigerant diameter of 1.1mm for our current system. Further study showed that the dissipative sources (e.g., the fluid friction and the unbalanced magnetic forces) in AMRRs, which were overlooked by previous investigations, could significantly contribute to entropy generations.
van Oss, C J; Good, R J; Chaudhury, M K
1986-04-11
All antigen-antibody (AG-AB) bonds are weak physical bonds; covalent bonds are not encountered. The main bonds involved are: (I) Coulombic bonds; (II) Ca2+-bridges; (III) hydrogen bonds; (IV) Lifshitz--van der Waals bonds. Combinations of III and IV occur as the "bonds" usually alluded to as hydrophobic (H phi) interactions. In primary bonds, mainly types I and IV occur; types II and III are quite rare. Secondary bonds, which evolve after a certain time-lapse (varying from minutes to days), mainly involve type IV bonds and H phi interactions, while hydrogen bonds sensu stricto have been known to play a role in rare instances. In affinity chromatography involving AG-AB interactions, complete elution with mild eluents usually is desirable. It would thus appear essential to let little time elapse between AG-AB complex formation and the elution step, to minimize strengthening of the AG-AB interaction by secondary bond formation. For expeditious elution, it also is important to avoid using dehydrating agents (which tend to decrease the bond distance between AG and AB and thus could strengthen the bond in a number of ways). The degree of involvement of types I and IV bonds as well as of H phi interactions varies considerably among different AG-AB systems. These components thus have to be measured separately in order to determine the optimal conditions for elution. The parameters of the liquid medium that may be modulated to influence dissociation (or association) are, for example, surface tension, pH, ionic strength, dielectric constant, temperature, admixture of dehydrating agents or of chaotropic salts. The influence of variations in each of these parameters on types I, III and IV bonds (and thus also on H phi interactions) will be delineated. Because of the misleading implications of the term "hydrophobic interactions", it seems preferable henceforth to allude to them as "interfacial forces". PMID:3711190
Optimization of the Geometric Beta for the SSR2 Cavities of the Project X
Solyak, N.; Vostrikov, A.; Yakovlev, V.P.; /Fermilab; Awida, M.H.; Berrutti, P.; Gonin, I.V.; /Fermilab
2012-05-01
Project X based on the 3 GeV CW superconducting Linac and is currently in the R&D phase. The CW SC Linac starts from a low-energy SCRF section (2.1 - 165 MeV) containing three different types of resonators. HWR f = 162.5 MHz (2.1 - 11 MeV) having beta= 0.11, SSR1 f = 325 MHz (11 - 35 MeV) having beta = 0.21. In this paper we present the analysis that lead to the final design of SSR2 f = 325 MHz cavity (35 - 165 MeV). We present the results of optimization of the geometric beta and the comparison between single, double and triple spoke resonators used in Project X frontend. A {beta} optimization has been carried out for the last spoke cavity section of Project X front end. The optimization process of {beta}{sub opt} for a single spoke resonator family SSR2 shown that {beta}{sub opt} = 0.47 looks better than the previous choice, which is {beta}{sub opt} = 0.4. This change can save some cavities and provide the same final energy for this section, 160 MeV. Single double and triple spoke resonator performances have been compared. The best option is the single spoke resonator SSR2 because the NTTF of a multi-spoke resonator is much narrower than a single one. In the energy range considered (40-160 MeV) the most efficient resonator is the single spoke one.
A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms
NASA Technical Reports Server (NTRS)
Smeltzer, Stanley S., III; Finckenor, Jeffrey L.
1999-01-01
A natural process for any engineer, scientist, educator, etc. is to seek the most efficient method for accomplishing a given task. In the case of structural design, an area that has a significant impact on the structural efficiency is joint design. Unless the structure is machined from a solid block of material, the individual components which compose the overall structure must be joined together. The method for joining a structure varies depending on the applied loads, material, assembly and disassembly requirements, service life, environment, etc. Using both metallic and fiber reinforced plastic materials limits the user to two methods or a combination of these methods for joining the components into one structure. The first is mechanical fastening and the second is adhesive bonding. Mechanical fastening is by far the most popular joining technique; however, in terms of structural efficiency, adhesive bonding provides a superior joint since the load is distributed uniformly across the joint. The purpose of this paper is to develop a method for optimizing single-lap joint adhesive bonded structures using both gradient and genetic algorithms and comparing the solution process for each method. The goal of the single-lap joint optimization is to find the most efficient structure that meets the imposed requirements while still remaining as lightweight, economical, and reliable as possible. For the single-lap joint, an optimum joint is determined by minimizing the weight of the overall joint based on constraints from adhesive strengths as well as empirically derived rules. The analytical solution of the sin-le-lap joint is determined using the classical Goland-Reissner technique for case 2 type adhesive joints. Joint weight minimization is achieved using a commercially available routine, Design Optimization Tool (DOT), for the gradient solution while an author developed method is used for the genetic algorithm solution. Results illustrate the critical design variables as a function of adhesive properties and convergences of different joints based on the two optimization methods.
Tsai, Hui-Hsu Gavin; Lee, Jian-Bin; Li, Hung-Sheng; Hou, Tsai-Yi; Chu, Wen-Yuan; Shen, Po-Chuan; Chen, Ying-Yu; Tan, Chun-Jui; Hu, Jia-Cheng; Chiu, Chih-Chiang
2015-05-01
The trans isomers of fatty acids are found in human adipose tissue. These isomers have been linked with deleterious health effects (e.g., coronary artery disease). In this study, we performed molecular dynamics simulations to investigate the structures and dynamic properties of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) and 1-palmitoyl-2-elaidoyl sn-glycero-3-phosphatidylcholine (PEPC) lipid bilayers. The geometry of the olefinic bond and membrane packing effects significantly influenced the conformations and dynamics of the two C-C single bonds adjacent to the olefinic bond. For the PEPC lipid, the two C-C single bonds adjacent to the olefinic bond adopted mainly nonplanar skew-trans and planar cis-trans motifs; although the cis conformation featured relatively strong steric repulsion, it was stabilized through membrane packing because its planar structure is more suitable for membrane packing. Moreover, membrane packing effects stabilized the planar transition state for conformational conversion to a greater extent than they did with the nonplanar transition state, thereby affecting the dynamics of conformational conversion. The rotational motions of the first neighboring C-C single bonds were much faster than those of typical saturated C-C single bonds; in contrast, the rotational motions of the second neighboring C-C single bonds were significantly slower than those of typical saturated torsion angles. The packing of PEPC lipids is superior to that of POPC lipids, leading to a smaller area per lipid, a higher order parameter and a smaller diffusion coefficient. The distinct properties of POPC and PEPC lipids result in PEPC lipids forming microdomains within a POPC matrix. PMID:25732027
NASA Astrophysics Data System (ADS)
Moroni, Giovanni; Syam, Wahyudin P.; Petrò, Stefano
2014-08-01
Product quality is a main concern today in manufacturing; it drives competition between companies. To ensure high quality, a dimensional inspection to verify the geometric properties of a product must be carried out. High-speed non-contact scanners help with this task, by both speeding up acquisition speed and increasing accuracy through a more complete description of the surface. The algorithms for the management of the measurement data play a critical role in ensuring both the measurement accuracy and speed of the device. One of the most fundamental parts of the algorithm is the procedure for fitting the substitute geometry to a cloud of points. This article addresses this challenge. Three relevant geometries are selected as case studies: a non-linear least-squares fitting of a circle, sphere and cylinder. These geometries are chosen in consideration of their common use in practice; for example the sphere is often adopted as a reference artifact for performance verification of a coordinate measuring machine (CMM) and a cylinder is the most relevant geometry for a pin-hole relation as an assembly feature to construct a complete functioning product. In this article, an improvement of the initial point guess for the Levenberg-Marquardt (LM) algorithm by employing a chaos optimization (CO) method is proposed. This causes a performance improvement in the optimization of a non-linear function fitting the three geometries. The results show that, with this combination, a higher quality of fitting results a smaller norm of the residuals can be obtained while preserving the computational cost. Fitting an ‘incomplete-point-cloud’, which is a situation where the point cloud does not cover a complete feature e.g. from half of the total part surface, is also investigated. Finally, a case study of fitting a hemisphere is presented.
An optimized orbital parameters model for geometric correction of space images
NASA Astrophysics Data System (ADS)
Safdarinezhad, Alireza; Zoej, Mohammad Javad Valadan
2015-03-01
The Orbital Parameters Model (OPM) is a physically constrained model for geometrical correction of satellite images with dynamic geometry. In this model, Keplerian parameters are used to establish an exact relationship between image space and object space. However, insufficient information regarding the precision of the observed Keplerian elements requires certain complementary parameters to be imposed on the model. These parameters lead to an undesirable increase in the number of required Ground Control Points (GCPs). To overcome this problem, unknown parameters may be introduced as quasi-observations in the adjustment procedure. This paper demonstrates that quasi-observation weights have a large impact on the OPM solution. For the first time, a Variance Components Estimation (VCE) technique is used to optimize the weights of quasi-observations when information on their observed precision is lacking. The proposed method is evaluated on two different SPOT datasets and one RapidEye dataset of stereo images. The results demonstrate the efficiency of VCE-based OPM where the highest expected accuracy of 3D information is reached even with three or four GCPs.
Optimal tubular adhesive-bonded lap joint of the carbon fiber epoxy composite shaft
NASA Astrophysics Data System (ADS)
Kim, Ki S.; Kim, Won T.; Lee, Dai G.; Jun, Eui J.
The effects of the adhesive thickness and the adherend surface roughness on the fatigue strength of a tubular adhesive-bonded single lap joint were investigated using fatigue test specimens whose adherends were made of S45C carbon steel. Results of fatigue tests showed that the optimal arithmetic surface roughness of the adherends is about 2 microns and the optimal adhesive thickness is about 0.15 mm. Using these values, the prototype torsional adhesive joints were manufactured for power transmission shafts of an automotive vehicle or a small helicopter, and static tests under torque were performed on a single-lap joint, a single-lap joint with scarf, a double-lap joint, and a double-lap joint with scarf. It was found that the double-lap joint was superior among the joints, in terms of torque capacity and manufacturing cost.
NASA Astrophysics Data System (ADS)
Joseph Fernandus, M.; Senthilkumar, T.; Balasubramanian, V.; Rajakumar, S.
2012-11-01
The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by fusion welding lies in the formation of oxide films and brittle intermetallic in the bond region which affects the integrity of the joints. However, diffusion bonding is a suitable process to join these two materials as no such characteristic defects are produced at the joints. The diffusion bonding process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the specimen play a major role in determining the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the strengths of diffusion bonded AZ80 magnesium and AA6061 aluminum alloys dissimilar joints from the process parameters based on central composite factorial design. Response surface methodology was applied to optimize the process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it was found that the bonds produced with the temperature of 405.87 °C, pressure of 7.87 MPa, holding time of 29.02 min and surface roughness of 0.10 ?m exhibited maximum shear strength and bonding strength of 57.70 and 76.90 MPa, respectively. The intermetallic formation at the interface was identified.
Bertsimas, Dimitris J.
In this paper, we show a significant role that geometric properties of uncertainty sets, such as symmetry, play in determining the power of robust and finitely adaptable solutions in multistage stochastic and adaptive ...
Lu, Caijiang; Xu, Changbao; Wang, Lei; Gao, Jipu; Gui, Junguo; Lin, Chenghui
2014-11-01
This paper reports an optimized end-bonding magnetoelectric (ME) heterostructure FeCuNbSiB-PZT-FeCuNbSiB (FPF) for sensitive magnetic field sensor. The heterostructure is made by attaching magnetostrictive Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB) foils at the free ends of piezoelectric Pb(Zr1-x,Tix)O3 (PZT) plates. Due to the structural advantages, the FPF has ?3.12 times larger resonance voltage coefficient (?ME,r) than traditional FeCuNbSiB/PZT laminate. And compared with the Metglas-PZT-Metglas heterostructure, the FPF heterostructure has stronger ME responses for the excellent magnetic characteristics of FeCuNbSiB. In experiments, the FPF heterostructure is optimal designed through adjusting the thickness of PZT plate (tp) and the length of FeCuNbSiB foil (L). The results demonstrate that the maximum ?ME,r of 662.1 (V/cm Oe) is observed at 13 Oe DC bias magnetic field when L = 15 mm and tp = 0.6 mm. Based on the giant ME coupling, the DC magnetic field sensitivity for the optimized FPF heterostructure is 3.89 nT at resonant frequency. These results are very promising for the cheap room-temperature magnetic field sensing technology. PMID:25430140
NASA Technical Reports Server (NTRS)
Hrinda, Glenn A.; Nguyen, Duc T.
2008-01-01
A technique for the optimization of stability constrained geometrically nonlinear shallow trusses with snap through behavior is demonstrated using the arc length method and a strain energy density approach within a discrete finite element formulation. The optimization method uses an iterative scheme that evaluates the design variables' performance and then updates them according to a recursive formula controlled by the arc length method. A minimum weight design is achieved when a uniform nonlinear strain energy density is found in all members. This minimal condition places the design load just below the critical limit load causing snap through of the structure. The optimization scheme is programmed into a nonlinear finite element algorithm to find the large strain energy at critical limit loads. Examples of highly nonlinear trusses found in literature are presented to verify the method.
NASA Astrophysics Data System (ADS)
Archer, Cristina; Ghaisas, Niranjan
2015-04-01
The energy generation at a wind farm is controlled primarily by the average wind speed at hub height. However, two other factors impact wind farm performance: 1) the layout of the wind turbines, in terms of spacing between turbines along and across the prevailing wind direction; staggering or aligning consecutive rows; angles between rows, columns, and prevailing wind direction); and 2) atmospheric stability, which is a measure of whether vertical motion is enhanced (unstable), suppressed (stable), or neither (neutral). Studying both factors and their complex interplay with Large-Eddy Simulation (LES) is a valid approach because it produces high-resolution, 3D, turbulent fields, such as wind velocity, temperature, and momentum and heat fluxes, and it properly accounts for the interactions between wind turbine blades and the surrounding atmospheric and near-surface properties. However, LES are computationally expensive and simulating all the possible combinations of wind directions, atmospheric stabilities, and turbine layouts to identify the optimal wind farm configuration is practically unfeasible today. A new, geometry-based method is proposed that is computationally inexpensive and that combines simple geometric quantities with a minimal number of LES simulations to identify the optimal wind turbine layout, taking into account not only the actual frequency distribution of wind directions (i.e., wind rose) at the site of interest, but also atmospheric stability. The geometry-based method is calibrated with LES of the Lillgrund wind farm conducted with the Software for Offshore/onshore Wind Farm Applications (SOWFA), based on the open-access OpenFOAM libraries. The geometric quantities that offer the best correlations (>0.93) with the LES results are the blockage ratio, defined as the fraction of the swept area of a wind turbine that is blocked by an upstream turbine, and the blockage distance, the weighted distance from a given turbine to all upstream turbines that can potentially block it. Based on blockage ratio and distance, an optimization procedure is proposed that explores many different layout variables and identifies, given actual wind direction and stability distributions, the optimal wind farm layout, i.e., the one with the highest wind energy production. The optimization procedure is applied to both the calibration wind farm (Lillgrund) and a test wind farm (Horns Rev) and a number of layouts more efficient than the existing ones are identified. The optimization procedure based on geometric models proposed here can be applied very quickly (within a few hours) to any proposed wind farm, once enough information on wind direction frequency and, if available, atmospheric stability frequency has been gathered and once the number of turbines and/or the areal extent of the wind farm have been identified.
NASA Astrophysics Data System (ADS)
Lan, Yihua; Li, Cunhua; Ren, Haozheng; Zhang, Yong; Min, Zhifang
2012-10-01
A new heuristic algorithm based on the so-called geometric distance sorting technique is proposed for solving the fluence map optimization with dose-volume constraints which is one of the most essential tasks for inverse planning in IMRT. The framework of the proposed method is basically an iterative process which begins with a simple linear constrained quadratic optimization model without considering any dose-volume constraints, and then the dose constraints for the voxels violating the dose-volume constraints are gradually added into the quadratic optimization model step by step until all the dose-volume constraints are satisfied. In each iteration step, an interior point method is adopted to solve each new linear constrained quadratic programming. For choosing the proper candidate voxels for the current dose constraint adding, a so-called geometric distance defined in the transformed standard quadratic form of the fluence map optimization model was used to guide the selection of the voxels. The new geometric distance sorting technique can mostly reduce the unexpected increase of the objective function value caused inevitably by the constraint adding. It can be regarded as an upgrading to the traditional dose sorting technique. The geometry explanation for the proposed method is also given and a proposition is proved to support our heuristic idea. In addition, a smart constraint adding/deleting strategy is designed to ensure a stable iteration convergence. The new algorithm is tested on four cases including head-neck, a prostate, a lung and an oropharyngeal, and compared with the algorithm based on the traditional dose sorting technique. Experimental results showed that the proposed method is more suitable for guiding the selection of new constraints than the traditional dose sorting method, especially for the cases whose target regions are in non-convex shapes. It is a more efficient optimization technique to some extent for choosing constraints than the dose sorting method. By integrating a smart constraint adding/deleting scheme within the iteration framework, the new technique builds up an improved algorithm for solving the fluence map optimization with dose-volume constraints.
Lingbo Zhu; Yonghao Xiu; Jianwen Xu; Dennis W. Hess; C. P. Wong
2006-01-01
Due to the surface smoothness of micromachined structures, strong adhesion forces between these fabricated structures and the substrate can be developed. The major adhesion mechanisms include capillary forces, hydrogen bonding, electrostatic forces and van der Waals forces. Once contact is made, the magnitude of these forces is in some cases sufficient to deform and pin these structures to the substrate,
NASA Astrophysics Data System (ADS)
Osusky, Lana Maria
The increase in the availability and power of computational resources over the last fifteen years has contributed to the development of many different types of numerical optimization methods and created a large area of research focussed on numerical aerodynamic shape optimization and, more recently, high-fidelity multidisciplinary optimization. Numerical optimization provides dramatic savings when designing new aerodynamic configurations, as it allows the designer to focus more on the development of a well-posed design problem rather than on performing an exhaustive search of the design space via the traditional cut-and-try approach, which is expensive and time-consuming. It also reduces the dependence on the designer's experience and intuition, which can potentially lead to more optimal designs. Numerical optimization methods are particularly attractive when designing novel, unconventional aircraft for which the designer has no pre-existing studies or experiences from which to draw; these methods have the potential to discover new designs that might never have been arrived at without optimization. This work presents an extension of an efficient gradient-based numerical aerodynamic shape optimization algorithm to enable optimization in turbulent flow. The algorithm includes an integrated geometry parameterization and mesh movement scheme, an efficient parallel Newton-Krylov-Schur algorithm for solving the Reynolds-Averaged Navier-Stokes (RANS) equations, which are fully coupled with the one-equation Spalart-Allmaras turbulence model, and a discrete-adjoint gradient evaluation. In order to develop an efficient methodology for optimization in turbulent flows, the viscous and turbulent terms in the ii governing equations were linearized by hand. Additionally, a set of mesh refinement tools was introduced in order to obtain both an acceptable control volume mesh and a sufficiently refined computational mesh from an initial coarse mesh. A series of drag minimization studies was carried out which show that the algorithm is able to maintain robustness in the mesh movement and flow analysis in the presence of large shape changes, an important requirement for performing exploratory optimizations aiming to discover novel configurations and for multidisciplinary optimization. Additionally, the algorithm is able to find incremental improvements when given well-designed initial planar and nonplanar geometries. A comparison of Euler-based and RANS-based optimizations highlights the importance of considering viscous and turbulent effects. A multi-point optimization demonstrates that the algorithm is able to address practical aerodynamic design problems.
Protas, Anna Maria; Ariani, Hanieh Hossein Nejad; Bonna, Arkadiusz; Polkowska-Nowakowska, Agnieszka; Pozna?ski, Jaros?aw; Bal, Wojciech
2013-10-01
In previous studies we showed that Ni(II) ions can hydrolytically cleave a peptide bond preceding Ser/Thr in peptides of a general sequence RN-(Ser/Thr)-Xaa-His-Zaa-RC, where RN and RC are any peptide sequences. A peptide library screening, assisted by accurate measurements of reaction kinetics for selected peptides, demonstrated the preference for bulky and aromatic residues at variable positions Xaa and Zaa [A. Kr??el, E. Kopera, A.M. Protas, A. Wys?ouch-Cieszy?ska, J. Pozna?ski, W. Bal, J. Am. Chem. Soc., 132 (2010) 3355-3366]. In this work we used a similar strategy to find out whether the next residue downstream to Zaa may influence the reaction rate. Using an Ac-Gly-Ala-Ser-Arg-His-Zaa-Baa-Arg-Leu-NH2 library, with Zaa and Baa positions containing all common amino acids except of Cys, we found a very strong preference for aromatic residues in both variable positions. This finding significantly limits the range of useful Xaa, Zaa and Baa substitutions, thus facilitating the search for optimal sequences for protein engineering applications [E. Kopera, A. Belczyk-Ciesielska, W. Bal, PLoS One 7 (2012) e36350]. PMID:23973681
Valuation and Optimal Exercise of the Wild Card Option in the Treasury Bond Futures Market
Alex Kane; Alan J. Marcus
1986-01-01
The Chicago Board of Trade Treasury Bond Futures Contract allows the short position several delivery options as to when and with which bond the contract will be settled. The timing option allows the short position to choose any business day in the delivery month to make delivery. In addition, the contract settlement price is locked in at 2:00 p.m. when
J. Sussmann; Guoqing Tang
1991-01-01
We illustrate the use of the techniques of modern geometric optimal control theory by studying the shortest paths for a model of a car that can move forwards and backwards. This problem was discussed in recent work by Reeds and Shepp who showed, by special methods, (a) that shortest path motion could always be achieved by means of trajectories of
Automated Reconstruction of Dendritic and Axonal Trees by Global Optimization with Geometric Priors
Engin Türetken; Germán González; Christian Blum; Pascal Fua
2011-01-01
We present a novel probabilistic approach to fully automated delineation of tree structures in noisy 2D images and 3D image\\u000a stacks. Unlike earlier methods that rely mostly on local evidence, ours builds a set of candidate trees over many different\\u000a subsets of points likely to belong to the optimal tree and then chooses the best one according to a global
Vanderbei, Robert J., E-mail: rvdb@princeton.edu [Princeton University, Department of Operations Research and Financial Engineering (United States); P Latin-Small-Letter-Dotless-I nar, Mustafa C., E-mail: mustafap@bilkent.edu.tr [Bilkent University, Department of Industrial Engineering (Turkey); Bozkaya, Efe B. [Sabanc Latin-Small-Letter-Dotless-I University, Faculty of Administrative Sciences (Turkey)] [Sabanc Latin-Small-Letter-Dotless-I University, Faculty of Administrative Sciences (Turkey)
2013-02-15
An American option (or, warrant) is the right, but not the obligation, to purchase or sell an underlying equity at any time up to a predetermined expiration date for a predetermined amount. A perpetual American option differs from a plain American option in that it does not expire. In this study, we solve the optimal stopping problem of a perpetual American option (both call and put) in discrete time using linear programming duality. Under the assumption that the underlying stock price follows a discrete time and discrete state Markov process, namely a geometric random walk, we formulate the pricing problem as an infinite dimensional linear programming (LP) problem using the excessive-majorant property of the value function. This formulation allows us to solve complementary slackness conditions in closed-form, revealing an optimal stopping strategy which highlights the set of stock-prices where the option should be exercised. The analysis for the call option reveals that such a critical value exists only in some cases, depending on a combination of state-transition probabilities and the economic discount factor (i.e., the prevailing interest rate) whereas it ceases to be an issue for the put.
Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi
2013-09-01
A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis. PMID:23834855
Tjäderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L.S.; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela R.; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.
2012-01-01
Objectives Contemporary adhesives lose their bond strength to dentin regardless of the bonding system used. This loss relates to the hydrolysis of collagen matrix of the hybrid layers. The preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability. Methods Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface. Results The identities, roles and function of collagenolytic enzymes in mineralized dentin has been gathered only within last 15 years, but they have already been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. Identifying responsible enzymes facilitates the development of new, more efficient methods to improve the stability of dentin-adhesive bond and durability of bond strength. Significance Understanding the nature and role of proteolytic degradation of dentin-adhesive interfaces has improved immensely and has practically grown to a scientific field of its own within only 10 years, holding excellent promise that stable resin-dentin bonds will be routinely available in a daily clinical setting already in a near future. PMID:22901826
Pervushin, K; Ono, A; Fernández, C; Szyperski, T; Kainosho, M; Wüthrich, K
1998-11-24
This paper describes the NMR observation of 15N---15N and 1H---15N scalar couplings across the hydrogen bonds in Watson-Crick base pairs in a DNA duplex, hJNN and hJHN. These couplings represent new parameters of interest for both structural studies of DNA and theoretical investigations into the nature of the hydrogen bonds. Two dimensional [15N,1H]-transverse relaxation-optimized spectroscopy (TROSY) with a 15N-labeled 14-mer DNA duplex was used to measure hJNN, which is in the range 6-7 Hz, and the two-dimensional hJNN-correlation-[15N,1H]-TROSY experiment was used to correlate the chemical shifts of pairs of hydrogen bond-related 15N spins and to observe, for the first time, hJHN scalar couplings, with values in the range 2-3.6 Hz. TROSY-based studies of scalar couplings across hydrogen bonds should be applicable for large molecular sizes, including protein-bound nucleic acids. PMID:9826668
Luo, Wen; Feng, Yiyu; Qin, Chengqun; Li, Man; Li, Shipei; Cao, Chen; Long, Peng; Liu, Enzuo; Hu, Wenping; Yoshino, Katsumi; Feng, Wei
2015-10-01
An important method for establishing a high-energy, stable and recycled molecular solar heat system is by designing and preparing novel photo-isomerizable molecules with a high enthalpy and a long thermal life by controlling molecular interactions. A meta- and ortho-bis-substituted azobenzene chromophore (AZO) is covalently grafted onto reduced graphene oxide (RGO) for solar thermal storage materials. High grafting degree and close-packed molecules enable intermolecular hydrogen bonds (H-bonds) for both trans-(E) and cis-(Z) isomers of AZO on the surface of nanosheets, resulting in a dramatic increase in enthalpy and lifetime. The metastable Z-form of AZO on RGO is thermally stabilized with a half-life of 52 days by steric hindrance and intermolecular H-bonds calculated using density functional theory (DFT). The AZO-RGO fuel shows a high storage capacity of 138 Wh kg(-1) by optimizing intermolecular H-bonds with a good cycling stability for 50 cycles induced by visible light at 520 nm. Our work opens up a new method for making advanced molecular solar thermal storage materials by tuning molecular interactions on a nano-template. PMID:26289389
NASA Astrophysics Data System (ADS)
Mohammed, Ahmed A. S.; Moussa, Walied A.; Lou, Edmond
2010-01-01
In this paper, the design of MEMS piezoresistive strain sensor is described. ANSYS®, finite element analysis (FEA) software, was used as a tool to model the performance of the silicon-based sensor. The incorporation of stress concentration regions (SCRs), to localize stresses, was explored in detail. This methodology employs the structural design of the sensor silicon carrier. Therefore, the induced strain in the sensing chip yielded stress concentration in the vicinity of the SCRs. Hence, this concept was proved to enhance the sensor sensitivity. Another advantage of the SCRs is to reduce the sensor transverse gauge factor, which offered a great opportunity to develop a MEMS sensor with minimal cross sensitivity. Two basic SCR designs were studied. The depth of the SCRs was also investigated. Moreover, FEA simulation is utilized to investigate the effect of the sensing element depth on the sensor sensitivity. Simulation results showed that the sensor sensitivity is independent of the piezoresistors' depth. The microfabrication process flow was introduced to prototype the different sensor designs. The experiments covered operating temperature range from -50 °C to +50 °C. Finally, packaging scheme and bonding adhesive selection were discussed. The experimental results showed good agreement with the FEA simulation results. The findings of this study confirmed the feasibility of introducing SCRs in the sensor silicon carrier to improve the sensor sensitivity while using relatively high doping levels (5 × 1019 atoms cm-3). The fabricated sensors have a gauge factor about three to four times higher compared to conventional thin-foil strain gauges.
Optimization of direct currents to enhance dentine bonding of simplified one-step adhesive.
Chen, Hongfei; Fu, Dongjie; Yang, Hongye; Liu, Yinchen; Huang, Yanyu; Huang, Cui
2014-08-01
The aim of this study was to investigate the effects of different direct current intensities on dentine bonding effectiveness of Clearfil S(3) Bond and on cell viability of human dental pulp cells (HDPCs). Thirty-five-third molars were sectioned and ground to provide flat surfaces. Clearfil S(3) Bond was applied under different current conditions for 30 s and then resin composite was built up. Specimens were processed for microtensile bond strength (µTBS) testing and for nanoleakage investigation using scanning electron microscopy. Primary HDPCs isolated from premolars were stimulated with different intensities of electric current for 30 s. Then, cell viability was tested using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Specimens bonded with application of electrical current intensities of 50, 60, 70, and 90 µA exhibited a significant increase in immediate µTBS compared with all other groups. Bonded interfaces prepared using electrically assisted current application showed reduced interfacial nanoleakage upon scanning electron microscopy. Electric current application, from 20 to 70 µA, had no effect on the viability of HDPCs. This study provides further evidence for its future clinical use. PMID:24965668
Dispersion engineered silicon nitride waveguides by geometrical and refractive-index optimization
Boggio, J M Chavez; Fremberg, T; Haynes, R; Roth, M M; Eisermann, R; Lisker, M; Zimmermann, L; Boehm, M
2014-01-01
Dispersion engineering in silicon nitride (SiX NY ) waveguides is investigated through the optimization of the waveguide transversal dimensions and refractive indices in a multi-cladding arrangement. Ultra-flat dispersion of -84.0 +/- 0.5 ps/nm/km between 1700 and 2440 nm and 1.5 +/- 3 ps/nm/km between 1670 and 2500 nm is numerically demonstrated. It is shown that typical refractive index fluctuations as well as dimension fluctuations during the fabrication of the SiX NY waveguides are a limitation for obtaining ultra-flat dispersion profiles. Single- and multi-cladding waveguides are fabricated and their dispersion profiles measured (over nearly 1000 nm) using a low-coherence frequency domain interferometric technique. By appropriate thickness optimization, the zero-dispersion wavelength is tuned over a large spectral range in both single-cladding waveguides and multi-cladding waveguides with small refractive index contrast (3 %). A flat dispersion profile with 3.2 ps/nm/km variation over 500 nm is obtained ...
Optimal image alignment with random projections of manifolds: algorithm and geometric analysis.
Kokiopoulou, Effrosyni; Kressner, Daniel; Frossard, Pascal
2011-06-01
This paper addresses the problem of image alignment based on random measurements. Image alignment consists of estimating the relative transformation between a query image and a reference image. We consider the specific problem where the query image is provided in compressed form in terms of linear measurements captured by a vision sensor. We cast the alignment problem as a manifold distance minimization problem in the linear subspace defined by the measurements. The transformation manifold that represents synthesis of shift, rotation, and isotropic scaling of the reference image can be given in closed form when the reference pattern is sparsely represented over a parametric dictionary. We show that the objective function can then be decomposed as the difference of two convex functions (DC) in the particular case where the dictionary is built on Gaussian functions. Thus, the optimization problem becomes a DC program, which in turn can be solved globally by a cutting plane method. The quality of the solution is typically affected by the number of random measurements and the condition number of the manifold that describes the transformations of the reference image. We show that the curvature, which is closely related to the condition number, remains bounded in our image alignment problem, which means that the relative transformation between two images can be determined optimally in a reduced subspace. PMID:21189239
Spatiotemporal and geometric optimization of sensor arrays for detecting analytes fluids
Lewis, Nathan S.; Freund, Michael S.; Briglin, Shawn M.; Tokumaru, Phil; Martin, Charles R.; Mitchell, David T.
2006-10-17
Sensor arrays and sensor array systems for detecting analytes in fluids. Sensors configured to generate a response upon introduction of a fluid containing one or more analytes can be located on one or more surfaces relative to one or more fluid channels in an array. Fluid channels can take the form of pores or holes in a substrate material. Fluid channels can be formed between one or more substrate plates. Sensor can be fabricated with substantially optimized sensor volumes to generate a response having a substantially maximized signal to noise ratio upon introduction of a fluid containing one or more target analytes. Methods of fabricating and using such sensor arrays and systems are also disclosed.
Spatiotemporal and geometric optimization of sensor arrays for detecting analytes in fluids
Lewis, Nathan S. (La Canada, CA); Freund, Michael S. (Winnipeg, CA); Briglin, Shawn S. (Chittenango, NY); Tokumaru, Phillip (Moorpark, CA); Martin, Charles R. (Gainesville, FL); Mitchell, David (Newtown, PA)
2009-09-29
Sensor arrays and sensor array systems for detecting analytes in fluids. Sensors configured to generate a response upon introduction of a fluid containing one or more analytes can be located on one or more surfaces relative to one or more fluid channels in an array. Fluid channels can take the form of pores or holes in a substrate material. Fluid channels can be formed between one or more substrate plates. Sensor can be fabricated with substantially optimized sensor volumes to generate a response having a substantially maximized signal to noise ratio upon introduction of a fluid containing one or more target analytes. Methods of fabricating and using such sensor arrays and systems are also disclosed.
Jungbauer, Stefan H; Huber, Stefan M
2015-09-23
In contrast to hydrogen bonding, which is firmly established in organocatalysis, there are still very few applications of halogen bonding in this field. Herein, we present the first catalytic application of cationic halogen-bond donors in a halide abstraction reaction. First, halopyridinium-, haloimidazolium-, and halo-1,2,3-triazolium-based catalysts were systematically tested. In contrast to the pyridinium compounds, both the imidazolium and the triazolium salts showed promising potency. For the haloimidazolium-based organocatalysts, we could show that the catalytic activity is based on halogen bonding using, e.g., the chlorinated derivatives as reference compounds. On the basis of these studies, halobenzimidazolium organocatalysts were then investigated. Monodentate compounds featured the same trends as the corresponding imidazolium analogues but showed a stronger catalytic activity. In order to prepare bidentate versions which are preorganized for anion binding, a new class of rigid bis(halobenzimidazolium) compounds was synthesized and structurally characterized. The corresponding syn isomer showed unprecedented catalytic potency and could be used in as low as 0.5 mol % in the benchmark reaction of 1-chloroisochroman with a silyl enol ether. Calculations confirmed that the syn isomer may bind in a bidentate fashion to chloride. The respective anti isomer is less active and binds halides in a monodentate fashion. Kinetic investigations confirmed that the syn isomer led to a 20-fold rate acceleration compared to a neutral tridentate halogen-bond donor. The strength of the preorganized halogen-bond donor seems to approach the limit under the reaction conditions, as decomposition is observed in the presence of chloride in the same solvent at higher temperatures. Calorimetric titrations of the syn isomer with bromide confirmed the strong halogen-bond donor strength of the former (K ? 4 × 10(6) M(-1), ?G ? 38 kJ/mol). PMID:26329271
Optimizing dentin bond durability: strategies to prevent hydrolytic degradation of the hybrid layer
Tjäderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L.S.; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.
2014-01-01
Objectives Endogenous dentin collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, are responsible for the time-related hydrolysis of collagen matrix of the hybrid layers. As the integrity of the collagen matrix is essential for the preservation of long-term dentin bond strength, inhibition or inactivation of endogenous dentin proteases is necessary for durable resin-bonded composite resin restorations. Methods Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface. Several tentative approaches to prevent enzyme function either directly or indirectly have been proposed in the literature. Results Chlorhexidine, a general inhibitor of both MMPs and cysteine cathepsins, applied before primer/adhesive application is the most tested method. In general, these experiments have shown that enzyme inhibition is a promising scheme to improve hybrid layer preservation and bond strength durability. Other enzyme inhibitors, e.g. enzyme-inhibiting monomers and antimicrobial compounds, may be considered promising alternatives that would allow more simple clinical application than chlorhexidine. Cross-linking collagen and/or dentin organic matrix-bound enzymes could render hybrid layer organic matrix resistant to degradation, and complete removal of water from the hybrid layer with ethanol wet bonding or biomimetic remineralization should eliminate hydrolysis of both collagen and resin components. Significance Identification of the enzymes responsible for the hydrolysis of hybrid layer collagen and understanding their function has prompted several innovative approaches to retain the hybrid layer integrity and strong dentin bonding. The ultimate goal, prevention of collagen matrix degradation with techniques and commercially available materials that are simple and effective in clinical settings may be achievable in several ways, and will likely become reality in the near future. PMID:23953737
NASA Astrophysics Data System (ADS)
Asfahani, J.; Tlas, M.
2015-03-01
An easy and practical method for interpreting residual gravity anomalies due to simple geometrically shaped models such as cylinders and spheres has been proposed in this paper. This proposed method is based on both the deconvolution technique and the simplex algorithm for linear optimization to most effectively estimate the model parameters, e.g., the depth from the surface to the center of a buried structure (sphere or horizontal cylinder) or the depth from the surface to the top of a buried object (vertical cylinder), and the amplitude coefficient from the residual gravity anomaly profile. The method was tested on synthetic data sets corrupted by different white Gaussian random noise levels to demonstrate the capability and reliability of the method. The results acquired show that the estimated parameter values derived by this proposed method are close to the assumed true parameter values. The validity of this method is also demonstrated using real field residual gravity anomalies from Cuba and Sweden. Comparable and acceptable agreement is shown between the results derived by this method and those derived from real field data.
Insect kinin analogs with cis-peptide bond motif 4-aminopyroglutamate: Optimal stereochemistry
Technology Transfer Automated Retrieval System (TEKTRAN)
The insect kinins are present in a wide variety of insects and function as potent diuretic peptides, though they are subject to rapid degradation by internal peptidases. Insect kinin analogs incorporating stereochemical variants of (2S,4S)-4-aminopyroglutamate (APy), a cis-peptide bond motif, demon...
Extremal Optimization for Ground States of the Sherrington-Kirkpatrick Spin Glass with Levy Bonds
NASA Astrophysics Data System (ADS)
Boettcher, Stefan
Ground states of Ising spin glasses on fully connected graphs are studied for a broadly distributed bond family. In particular, bonds J distributed according to a Levy distribution P(J) / 1/|J|1+?; |J| > 1; are investigated for a range of powers ?. We determine ground state energy density variation with ? and their finite-size corrections. We find that the energies attain universally the Parisi-energy of the SK as long as the second moment of P (J) exists (? > 2). They compare favorably with recent one-step replica symmetry breaking predictions well below ? = 2. At and just below ? = 2, the simulations deviate significantly from theoretical expectations. The finite-size investigation reveals that the corrections exponent ? decays from the putative SK value ?SK = = 2/3 already well above ? = 2, at which point it reaches a minimum.
Soft Chelating Irrigation Protocol Optimizes Bonding Quality of Resilon\\/Epiphany Root Fillings
Gustavo De-Deus; Fátima Namen; João Galan; Matthias Zehnder
2008-01-01
This study was designed to test the impact of either a strong (MTAD) or a soft (1-hydroxyethylidene-1, 1-bisphosphonate [HEPB]) chelating solution on the bond strength of Resilon\\/Epiphany root fillings. Both 17% EDTA and the omission of a chelator in the irrigation protocol were used as reference treatments. Forty extracted human upper lateral incisors were prepared using different irrigation protocols (n
Lorenzo, M C; Portillo, M; Moreno, P; Montero, J; García, A; Santos-del Riego, S E; Albaladejo, A
2015-02-01
The surfaces of 63 extracted premolar teeth were processed with intense ultrashort laser pulses (??=?795 nm; pulse duration, 120 fs; repetition rate, 1 kHz) to produce cross patterns with different pitches (s) in the micrometer range in order to evaluate the influence of such microstructures on the shear bond strengths of orthodontic brackets to enamel. The samples were classified in nine groups corresponding to the control group (raw samples) and eight different laser-processed groups (cross patterns with s increasing from 15 to 180 ?m). Brackets were luted with Transbond(TM) XT adhesive resin to all the samples; after 72 h, they all were submitted to strength test in a universal testing machine. Additionally, a third of the samples underwent morphological analysis of the debonded surface by means of scanning electron microscope microscopy and an analysis of the failure mode based on the adhesive remnant index. The results showed that enamel microstructuring with ultrashort laser pulses remarkably increase the bond strength of brackets. Dense cross patterns (s?bond strengths as compared to control group whereas light ones (s?>?90 ?m) give rise to smaller improvements of the bond strength. A strong correlation of this behavior with the predominant failure mode in both scenarios was found. So far, the best compromise between suitable adhesive efficiency, processing time minimization, and enamel surface preservation suggests the performance of cross patterns with pitches in the order of 90 ?m. PMID:24249356
NASA Astrophysics Data System (ADS)
Haisma, Jan; Hattu, Nico; (Dook) Pulles, J. T. C. M.; Steding, Esther; Vervest, Jan C. G.
2007-09-01
We present a number of recent evaluations of direct bonding, a glueless bonding technology, performed under ambient conditions. If combined with bond-strengthening, this geometry-conserving technology is well suited for an application in far ultraviolet immersion lithography. Our term beyond direct bonding refers to taking at least one additional technological step beyond direct bonding, involving chemical interface engineering, advanced silicon-on-insulator (SOI) technology, whereby the unwanted influence of dilatation mismatch is obviated. The combination of successive direct bonding, nanopillar lattice structures and silicon-technological engineering makes it possible for us to arrange quantum dots, wires, and planes in a transversal cascade. We also address the interrelationship between direct bonding and elasticity, as well as plasticity; the latter is in relation to direct bonded glass wafers that are thermally treated to create the geometric shape, e.g., required for specific lab-on-a-chip components with a three-dimensional overall configuration.
NASA Astrophysics Data System (ADS)
Sato, S.; Hatano, T.; Kuroda, T.; Furuya, K.; Hara, S.; Enoeda, M.; Takatsu, H.
1998-10-01
Optimum bonding conditions were studied on the Hot Isostatic Pressing (HIP) bonded joints of type 316L austenitic stainless steel and Dispersion Strengthened Copper alloy (DSCu) for application to the ITER shielding blanket / first wall. HIP bonded joints were fabricated at temperatures in a 980-1050°C range, and a series of mechanical tests and metallurgical observations were conducted on the joints. Also, bondability of two grades of DSCu (Glidcop Al-25 ® and Al-15 ®) with SS316L was examined in terms of mechanical properties of the HIP bonded joints. From those studies it was concluded that the HIP temperature of 1050°C was an optimal condition for obtaining higher ductility, impact values and fatigue strength. Also, SS316L/Al-15 joints showed better results in terms of ductility and impact values compared with SS316L/Al-25 joints.
Bhattacharya, Debswapna; Cheng, Jianlin
2013-01-01
One of the major limitations of computational protein structure prediction is the deviation of predicted models from their experimentally derived true, native structures. The limitations often hinder the possibility of applying computational protein structure prediction methods in biochemical assignment and drug design that are very sensitive to structural details. Refinement of these low-resolution predicted models to high-resolution structures close to the native state, however, has proven to be extremely challenging. Thus, protein structure refinement remains a largely unsolved problem. Critical assessment of techniques for protein structure prediction (CASP) specifically indicated that most predictors participating in the refinement category still did not consistently improve model quality. Here, we propose a two-step refinement protocol, called 3Drefine, to consistently bring the initial model closer to the native structure. The first step is based on optimization of hydrogen bonding (HB) network and the second step applies atomic-level energy minimization on the optimized model using a composite physics and knowledge-based force fields. The approach has been evaluated on the CASP benchmark data and it exhibits consistent improvement over the initial structure in both global and local structural quality measures. 3Drefine method is also computationally inexpensive, consuming only few minutes of CPU time to refine a protein of typical length (300 residues). 3Drefine web server is freely available at http://sysbio.rnet.missouri.edu/3Drefine/. PMID:22927229
NASA Astrophysics Data System (ADS)
Kanatani, Kenichi
The “geometric AIC” and the “geometric MDL” have been proposed as model selection criteria for geometric fitting problems. These correspond to Akaike's “AIC” and Rissanen's “BIC” well known in the statistical estimation framework. Another well known criterion is Schwarz' “BIC”, but its counterpart for geometric fitting has not been known. This paper introduces the corresponding criterion, which we call the “geometric BIC”, and shows that it is of the same form as the geometric MDL. Our result gives a justification to the geometric MDL from the Bayesian principle.
Lin, Qisheng; Vetter, Jordan; Corbett, John D
2013-06-01
Sr3Au8Sn3 was synthesized through fusion of a stoichiometric amount of pure metals at 800 °C and annealing treatments at lower temperatures. Single-crystal X-ray diffraction analyses revealed that Sr3Au8Sn3 has a La3Al11-type Immm structure (a = 4.6767(8) Å, b = 9.646(2) Å, c = 14.170(2) Å, Z = 2) if annealed at 550 °C and above but a Ca3Au8Ge3-type structure (Pnnm, a = 9.6082(8) Å, b = 14.171(1) Å, c = 4.6719(4) Å, Z = 2) if annealed at 400 °C. The transition occurs at about 454 °C according to DTA data. Both structures feature columns of Sr-centered pentagonal and hexagonal prisms of Au and Sn stacked along the respective longest axial directions, but different "colorings" of the polyhedra are evident. In the high-temperature phase (Immm) all sites shared between the two prisms adopt 50:50 mixtures of Au/Sn atoms, whereas in the low-temperature phase (Pnnm) Au or Sn are completely ordered. A Klassengleiche group-subgroup relationship was established between these two structures. LMTO-ASA calculations reveal that ?E for the disorder-to-order transformation on cooling is driven mainly by optimization of the Au-Au and Au-Sn bond populations around the former mixed Au/Sn sites, particularly those with extremely short bonds at the higher temperature. These gains also overcome the smaller effect of ordering on the entropy decrease. PMID:23679918
R. Balamurugan; C. V. Ramakrishnan; N. Swaminathan
2011-01-01
This paper introduces a set of skeleton operators for characterizing topologies evolving in a bit-array represented structural\\u000a topology optimization problem. It is shown that the design generally converges to a stable skeleton fairly early in the optimization\\u000a process. It is observed that further optimization is more about finding optimal gross shape for the various branches of the\\u000a converged skeleton and
Park, Ga Young; Qayyum, Munzarin F.; Woertink, Julia; Hodgson, Keith O.; Hedman, Britt; Narducci Sarjeant, Amy A.; Solomon, Edward I.; Karlin, Kenneth D.
2012-01-01
Certain side-on peroxo dicopper(II) species with particularly low ?O–O (710–730 cm?1) have been found in equilibrium with their bis-?-oxo dicopper(III) isomer. An issue is whether such side-on peroxo bridges are further activated for O–O cleavage. In a previous study (Liang, H.-C., et al., J. Am. Chem. Soc. 2002, 124, 4170–4171), we showed that oxygenation of the three-coordinate complex [CuI(MeAN)]+ (MeAN=N-methyl-N,N-bis[3-(dimethylamino)propyl]amine) leads to a low-temperature stable [{CuII(MeAN)}2(?-?2:?2-O22?)]2+ peroxo species with low ?O–O (721 cm?1), as characterized by UV-Vis absorption and resonance Raman (rR) spectroscopies. Here, this complex has been crystallized as its SbF6? salt and an X-ray structure indicates the presence of an unusually long O–O bond (1.540(5) Å) consistent with the low ?O–O. EXAFS and rR spectroscopic and reactivity studies indicate the exclusive formation of [{CuII(MeAN)}2(?-?2:?2-O22?)]2+ without any bis-?-oxo-dicopper(III) isomer present. This is the first structure of a side-on peroxo dicopper(II) species with a significantly long and weak O–O bond. DFT calculations show that the weak O–O bond results from strong ? donation from the MeAN ligand to Cu that is compensated by a decrease in the extent of peroxo to Cu charge transfer. Importantly, the weak O–O bond does not reflect an increase in backbonding into the ?* orbital of the peroxide. Thus, although the O–O bond is unusually weak, this structure is not further activated for reductive cleavage to form a reactive bis-?-oxo-dicopper(III) species. These results highlight the necessity of understanding electronic structure changes associated with spectral changes for correlations to reactivity. PMID:22571744
NASA Astrophysics Data System (ADS)
Yoon, Yoonjin
There has been growing interest in air transportation community to develop a routing decision model based on probabilistic characterization of severe weather. In the probabilistic air traffic management (PATM), decisions are made based on the stochastic weather information in the expected total cost sense. Probabilistic approach aims to enhance routing flexibility and reduce the risks associated with uncertainty of the future weather. In this research, a geometric model is adopted to generate optimal route choice when the future weather is stochastic. The geometric recourse model (GRM) is a strategic PATM model that incorporates route hedging and en-route recourse options to respond to weather change. Hedged routes are routes other than the nominal or detour route, and aircraft is re-routed to fly direct to the destination, which is called recourse, when the weather restricted airspace become flyable. Aircraft takes either the first recourse or the second recourse: The first recourse occurs when weather clears before aircraft reaches it flying on the initial route. The second recourse occurs when the aircraft is at the weather region. There are two variations of GRM: Single Recourse Model (SRM) with first recourse only and Dual Recourse Model (DRM) with both the first and second recourse options. When the weather clearance time follows a uniform distribution, SRM becomes convex with optimal route being either the detour or a hedged route. The DRM has a special property when the maximum storm duration time is less than the flight time to the tip of the storm on the detour route: it is always optimal to take the nominal route. The performance study is conducted by measuring the cost saving from either SRM or DRM. The result shows that there are cases with substantial cost saving, reaching nearly 30% with DRM. The ground-airborne hybrid model is an extension of the GRM, where both ground holding as well as route hedging are considered. The optimal combination of ground delay and route choice is determined by weather characteristics as well as the ground-airborne cost ratio. The numerical analysis reveals that whenever ground delay is required, the optimal route choice is the nominal one, while a non-nominal route is optimal when the ground delay is zero. There exists a unique critical cost ratio associated with given weather condition, which determines whether ground holding is optimal or not.
Wang, Feng; Graetz, Jason; Moreno, M. Sergio; Ma, Chao; Wu, Lijun; Volkov, Vyacheslav; Zhu, Yimei
2011-02-22
Direct mapping of the lithium spatial distribution and the chemical state provides critical information on structure-correlated lithium transport in electrode materials for lithium batteries. Nevertheless, probing lithium, the lightest solid element in the periodic table, poses an extreme challenge with traditional X-ray or electron scattering techniques due to its weak scattering power and vulnerability to radiation damage. Here, we report nanoscale maps of the lithium spatial distribution in electrochemically lithiated graphite using electron energy loss spectroscopy in the transmission electron microscope under optimized experimental conditions. The electronic structure of the discharged graphite was obtained from the near-edge fine structure of the Li and C K-edges and ab initio calculations. A 2.7 eV chemical shift of the Li K-edge, along with changes in the density of states, reveals the ionic nature of the intercalated lithium with significant charge transfer to the graphene sheets. Direct mapping of lithium in graphite revealed nanoscale inhomogeneities (nonstoichiometric regions), which are correlated with local phase separation and structural disorder (i.e., lattice distortion and dislocations) as observed by high-resolution transmission electron microscopy. The surface solid?electrolyte interphase (SEI) layer was also imaged and determined to have a thickness of 10?50 nm, covering both edge and basal planes with LiF as its primary inorganic component. The Li K-edge spectroscopy and mapping, combined with electron microscopy-based structural analysis provide a comprehensive view of the structure-correlated lithium intercalation in graphite and of the formation of the SEI layer.
Zhu, Y.; Wang, F.; Graetz, J.; Moreno, M.S.; Ma, C.; Wu, L.; Volkov, V.
2011-02-01
Direct mapping of the lithium spatial distribution and the chemical state provides critical information on structure-correlated lithium transport in electrode materials for lithium batteries. Nevertheless, probing lithium, the lightest solid element in the periodic table, poses an extreme challenge with traditional X-ray or electron scattering techniques due to its weak scattering power and vulnerability to radiation damage. Here, we report nanoscale maps of the lithium spatial distribution in electrochemically lithiated graphite using electron energy loss spectroscopy in the transmission electron microscope under optimized experimental conditions. The electronic structure of the discharged graphite was obtained from the near-edge fine structure of the Li and C K-edges and ab initio calculations. A 2.7 eV chemical shift of the Li K-edge, along with changes in the density of states, reveals the ionic nature of the intercalated lithium with significant charge transfer to the graphene sheets. Direct mapping of lithium in graphite revealed nanoscale inhomogeneities (nonstoichiometric regions), which are correlated with local phase separation and structural disorder (i.e., lattice distortion and dislocations) as observed by high-resolution transmission electron microscopy. The surface solid-electrolyte interphase (SEI) layer was also imaged and determined to have a thickness of 10-50 nm, covering both edge and basal planes with LiF as its primary inorganic component. The Li K-edge spectroscopy and mapping, combined with electron microscopy-based structural analysis provide a comprehensive view of the structure-correlated lithium intercalation in graphite and of the formation of the SEI layer.
A quantum mechanics-based halogen bonding scoring function for protein-ligand interactions.
Yang, Zhuo; Liu, Yingtao; Chen, Zhaoqiang; Xu, Zhijian; Shi, Jiye; Chen, Kaixian; Zhu, Weiliang
2015-06-01
A quantum mechanics-based scoring function for halogen bonding interaction, namely XBScore(QM), is developed based on 18,135 sets of geometrical and energetical parameters optimized at M06-2X/aug-cc-pVDZ level. Applying the function on typical halogen bonding systems from Protein Data Bank demonstrates its strong ability of predicting halogen bonding as attractive interaction with strength up to -4 kcal mol(-1). With a diverse set of proteins complexed with halogenated ligands, a systematic evaluation demonstrates the integrative advantage of XBScore(QM) over 12 other scoring functions on halogen bonding in four aspects, viz. pseudo docking power, ranking power, scoring power, and genuine docking power. Thus, this study not only provides a practicable scoring function of halogen bonding for high throughput virtual screening, but also serves as a benchmark for evaluating the performance of current scoring functions on characterizing halogen bonding. PMID:25957658
]. In the case of SiGe HBT, our ap- proach applies to several problems: determining the base doping profile optimal doping profile (for the models used). The method described here can in addition handle a variety optimization problem has not been addressed in the literature. We start with the model of base transit time
NSDL National Science Digital Library
2011-01-01
This tool lets learners explore various geometric solids and their properties. Learners can manipulate and color each shape to explore the faces, edges, and vertices, and they can use this tool to investigate the relationship among the number of faces, vertices, and edges. This tool supports the 5-lesson unit "Geometric Solids and Their Properties" (cataloged separately).
NASA Technical Reports Server (NTRS)
Coe, P. L., Jr.; Huffman, J. K.
1979-01-01
An investigation conducted in the Langley 7 by 10 foot tunnel to determine the influence of an optimized leading-edge deflection on the low speed aerodynamic performance of a configuration with a low aspect ratio, highly swept wing. The sensitivity of the lateral stability derivative to geometric anhedral was also studied. The optimized leading edge deflection was developed by aligning the leading edge with the incoming flow along the entire span. Owing to spanwise variation of unwash, the resulting optimized leading edge was a smooth, continuously warped surface for which the deflection varied from 16 deg at the side of body to 50 deg at the wing tip. For the particular configuration studied, levels of leading-edge suction on the order of 90 percent were achieved. The results of tests conducted to determine the sensitivity of the lateral stability derivative to geometric anhedral indicate values which are in reasonable agreement with estimates provided by simple vortex-lattice theories.
Technology Transfer Automated Retrieval System (TEKTRAN)
The insect kinins are present in a wide variety of insects and function as potent diuretic peptides, though they are subject to rapid degradation by internal peptidases. Insect kinin analogs incorporating stereochemical variants of (2S,4S)-4-aminopyroglutamate (APy), a cis-peptide bond motif, demon...
NASA Astrophysics Data System (ADS)
Shoji, Mitsuo; Isobe, Hiroshi; Saito, Toru; Kitagawa, Yasutaka; Yamanaka, Shusuke; Kawakami, Takashi; Okumura, Mitsutaka; Yamaguchi, Kizashi
Physiochemical properties of compound I and II intermediate states for heme enzymes (catalase, peroxidase, P450) and inorganic models are investigated by hybrid density functional theory. Used theoretical models are composed of an oxoferryl porphyrin and an axial ligand, which are cresol, methylimidazole, methylthiol, and chloride for catalase, peroxidase, P450, and inorganic models, respectively. The oxoferryl bonds are characterized in terms of bond lengths and vibration frequencies. It is found that the oxoferryl bond lengths (the stretching frequency) are shorter (higher) than those of the X-ray crystal structures of enzymes, on the other hand for inorganic models, they are comparable with the experimental values. Spin density distributions showed that radical state at the compound I can be classified into two types: (1) porphyrin radical state and (2) axial ligand radical state. Peroxidase and inorganic model are in the former case and Catalase and P450 are in the later case at the present calculation models. Magnetic interactions between oxoferryl and ligand radical moieties are analyzed by the natural orbital analysis and it is showed that the effective exchange integral (J) values are strongly related to the radical spin density distributions: axial ligand radical tends to increase the antiferromagnetic interaction. Mössbauer shift parameters are also evaluated and it is shown that iron charge states are similar for these models.
Kukiattrakoon, Boonlert; Thammasitboon, Kewalin
2012-01-01
Objectives: This in vitro study evaluated the shear bond strength (SBS) of resin composite to feldspathic porcelain after acidulated phosphate fluoride (APF) gel treatment over different periods of time. Methods: One hundred and fifty-six feldspathic specimens were divided into 12 groups. Group C received no treatment (control group). Groups APF1 through APF10, ten experimental groups, were treated with 1.23% APF gel. Each group obtained 1 to 10 minutes of etching time in 1 minute increments, respectively. Group HF2 was treated with 9.6% hydrofluoric acid (HF) for 2 minutes. All specimens were then bonded to a resin composite cylinder using Adper Scotchbond Multi-purpose (3M ESPE) after silane (Monobond-S, Ivoclar Vivadent AG) application. Specimens were stored at 37ºC for 24 hours before the SBS was performed and were recorded in MPa at fracture. Data were analyzed using one-way ANOVA and Tukey’s test (?=.05). Results: HF etching yielded the highest SBS (18.0 ± 1.5 MPa), which was not significantly different from APF gel etching for 6 to 10 minutes (16.0 ± 2.1 to 17.2 ± 1.6 MPa) (P>.05). Conclusions: APF gel etching for 6 minutes might be used as an alternative etchant to HF acid for bonding resin composite to silanized feldspathic porcelain. PMID:22229009
NASA Astrophysics Data System (ADS)
Talman, Richard
1999-10-01
Mechanics for the nonmathematician-a modern approach For physicists, mechanics is quite obviously geometric, yet the classical approach typically emphasizes abstract, mathematical formalism. Setting out to make mechanics both accessible and interesting for nonmathematicians, Richard Talman uses geometric methods to reveal qualitative aspects of the theory. He introduces concepts from differential geometry, differential forms, and tensor analysis, then applies them to areas of classical mechanics as well as other areas of physics, including optics, crystal diffraction, electromagnetism, relativity, and quantum mechanics. For easy reference, Dr. Talman treats separately Lagrangian, Hamiltonian, and Newtonian mechanics-exploring their geometric structure through vector fields, symplectic geometry, and gauge invariance respectively. Practical perturbative methods of approximation are also developed. Geometric Mechanics features illustrative examples and assumes only basic knowledge of Lagrangian mechanics. Of related interest . . . APPLIED DYNAMICS With Applications to Multibody and Mechatronic Systems Francis C. Moon A contemporary look at dynamics at an intermediate level, including nonlinear and chaotic dynamics. 1998 (0-471-13828-2) 504 pp. MATHEMATICAL PHYSICS Applied Mathematics for Scientists and Engineers Bruce Kusse and Erik Westwig A comprehensive treatment of the mathematical methods used to solve practical problems in physics and engineering. 1998 (0-471-15431-8) 680 pp.
NSDL National Science Digital Library
NCTM Illuminations
2000-01-01
This tool allows you to learn about various geometric solids and their properties. You can manipulate each solid, seeing it from every angle. You can also color each shape to explore the number of faces, edges, and vertices. With that information, you are challenged to investigate the following question: For any polyhedron, what is the relationship between the number of faces, vertices, and edges?
Xiao, Ruijuan; Li, Hong; Chen, Liquan
2015-01-01
Looking for solid state electrolytes with fast lithium ion conduction is an important prerequisite for developing all-solid-state lithium secondary batteries. By combining the simulation techniques in different levels of accuracy, e.g. the bond-valence (BV) method and the density functional theory (DFT), a high-throughput design and optimization scheme is proposed for searching fast lithium ion conductors as candidate solid state electrolytes for lithium rechargeable batteries. The screening from more than 1000 compounds is performed through BV-based method, and the ability to predict reliable tendency of the Li+ migration energy barriers is confirmed by comparing with the results from DFT calculations. ?-Li3PS4 is taken as a model system to demonstrate the application of this combination method in optimizing properties of solid electrolytes. By employing the high-throughput DFT simulations to more than 200 structures of the doping derivatives of ?-Li3PS4, the effects of doping on the ionic conductivities in this material are predicted by the BV calculations. The O-doping scheme is proposed as a promising way to improve the kinetic properties of this materials, and the validity of the optimization is proved by the first-principles molecular dynamics (FPMD) simulations. PMID:26387639
Xiao, Ruijuan; Li, Hong; Chen, Liquan
2015-01-01
Looking for solid state electrolytes with fast lithium ion conduction is an important prerequisite for developing all-solid-state lithium secondary batteries. By combining the simulation techniques in different levels of accuracy, e.g. the bond-valence (BV) method and the density functional theory (DFT), a high-throughput design and optimization scheme is proposed for searching fast lithium ion conductors as candidate solid state electrolytes for lithium rechargeable batteries. The screening from more than 1000 compounds is performed through BV-based method, and the ability to predict reliable tendency of the Li(+) migration energy barriers is confirmed by comparing with the results from DFT calculations. ?-Li3PS4 is taken as a model system to demonstrate the application of this combination method in optimizing properties of solid electrolytes. By employing the high-throughput DFT simulations to more than 200 structures of the doping derivatives of ?-Li3PS4, the effects of doping on the ionic conductivities in this material are predicted by the BV calculations. The O-doping scheme is proposed as a promising way to improve the kinetic properties of this materials, and the validity of the optimization is proved by the first-principles molecular dynamics (FPMD) simulations. PMID:26387639
NASA Astrophysics Data System (ADS)
Mukherjee, V.; Singh, N. P.; Yadav, R. A.
2011-03-01
Raman and IR spectra for 2,4,6-tri-fluorobenzoic acid have been recorded in the regions 50-4000 cm-1 and 400-4000 cm-1 respectively. Vibrational frequencies have been calculated by employing DFT method in dimeric form. SQM force field has also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. Raman activities calculated by DFT method have been converted to the corresponding Raman intensities using Raman scattering theory. Optimized geometries of the molecule have been interpreted and compared with the earlier reported experimental values for benzoic acid and some mono and di-fluorinated benzoic acids. Some of the vibrational frequencies of the title molecule are effected upon profusely with the fluorine substitutions in comparison to benzoic acid and these differences have been interpreted. The strong doubly hydrogen bonded interface of the dimerized system is well demonstrated by the red shift in O-H stretching frequency concomitant with the elongation of bond length.
Labyrinth stepped seal geometric optimization
Wernig, Marcus Daniel
1995-01-01
High-speed rotating machinery poses a challenging problem to designers and engineers. Interference between rotating and stationary elements can result in excessive wear, decreased machine performance, or machine failure. Labyrinth seals present a...
Eric Chisolm
2012-05-27
This is an introduction to geometric algebra, an alternative to traditional vector algebra that expands on it in two ways: 1. In addition to scalars and vectors, it defines new objects representing subspaces of any dimension. 2. It defines a product that's strongly motivated by geometry and can be taken between any two objects. For example, the product of two vectors taken in a certain way represents their common plane. This system was invented by William Clifford and is more commonly known as Clifford algebra. It's actually older than the vector algebra that we use today (due to Gibbs) and includes it as a subset. Over the years, various parts of Clifford algebra have been reinvented independently by many people who found they needed it, often not realizing that all those parts belonged in one system. This suggests that Clifford had the right idea, and that geometric algebra, not the reduced version we use today, deserves to be the standard "vector algebra." My goal in these notes is to describe geometric algebra from that standpoint and illustrate its usefulness. The notes are work in progress; I'll keep adding new topics as I learn them myself.
Sakhavand, Navid; Muthuramalingam, Prakash; Shahsavari, Rouzbeh
2013-06-25
The geometry and material property mismatch across the interface of hybrid materials with dissimilar building blocks make it extremely difficult to fully understand the lateral chemical bonding processes and design nanocomposites with optimal performance. Here, we report a combined first-principles study, molecular dynamics modeling, and theoretical derivations to unravel the detailed mechanisms of H-bonding, deformation, load transfer, and failure at the interface of polyvinyl alcohol (PVA) and silicates, as an example of hybrid materials with geometry and property mismatch across the interface. We identify contributing H-bonds that are key to adhesion and demonstrate a specific periodic pattern of interfacial H-bond network dictated by the interface mismatch and intramolecular H-bonding. We find that the maximum toughness, incorporating both intra- and interlayer strain energy contributions, govern the existence of optimum overlap length and thus the rupture of interfacial (interlayer) H-bond assemblies in natural and synthetic hybrid materials. This universally valid result is in contrast to the previous reports that correlate shear strength with rupture of H-bonds assemblies at a finite overlap length. Overall, this work establishes a unified understanding to explain the interplay between geometric constraints, interfacial H-bonding, materials characteristics, and optimal mechanical properties in hybrid organic-inorganic materials. PMID:23713817
ERIC Educational Resources Information Center
Frazier, Laura Corbin
2000-01-01
Introduces a science activity on the bonding of chemical compounds. Assigns students the role of either a cation or anion and asks them to write the ions they may bond with. Assesses students' understanding of charge, bonding, and other concepts. (YDS)
ERIC Educational Resources Information Center
Pollack, Rachel H.
2000-01-01
Notes trends toward increased borrowing by colleges and universities and offers guidelines for institutions that are considering issuing bonds to raise money for capital projects. Discussion covers advantages of using bond financing, how use of bonds impacts on traditional fund raising, other cautions and concerns, and some troubling aspects of…
Geometric Differential Evolution Alberto Moraglio
Togelius, Julian
formal generalization of traditional Par- ticle Swarm Optimization (PSO) that applies naturally to both continuous and combinatorial spaces. Differential Evo- lution (DE) is similar to PSO but it uses different for the traditional PSO algorithm. Using this formal algorithm, Geometric Differential Evolution (GDE), we formally
Carroll, Q
1983-01-01
Below is a review of the main geometrical points made in this paper. 1) Distortion is caused by: a. angling the beam against any spherical anatomy. b. leaving the beam perpendicular to the film when the part is tilted. c. angling the beam perpendicular to the part when it is tilted. 2) Distortion is negligible or absent when: a. angling the beam against a part that is parallel to the film. b. angling the beam one-half of the tilted-part-film angle. c. not angling when the part is parallel to the film. d. tomographing. 3) Magnification is not caused by: a. angling the beam, regardless of tube-to-tabletop distance compensation. b. tomography. 4) To evaluate a radiograph for positioning rotation, tilt, or flexion/extension, the pair of anatomical parts observed should be: a. stable and immovable. b. with their long axes nearly perpendicular to the direction of shift being evaluated. c. as close to the CR or center of the film as possible. d. as far from each other and from the midline as possible. Many of the geometrical factors involved in radiography are more complex than we often appreciate. They are sometimes taught in the form of "blanket" statements or rules that are oversimplified. Nonspecific, vague, or "blanket" questions in this area should be avoided in constructing the registry examinations. Finally, teaching in radiography should be based upon objective, repeatable, and verifiable experimentation rather than on appeal to authority. Such an approach will not only make radiography training more accurate, but also more exciting and fun. PMID:6856809
Effect of bonding on the performance of a piezoactuator-based active control system
NASA Technical Reports Server (NTRS)
Baz, A.; Poh, S.
1987-01-01
The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is studied. A Modified Independent Modal Space Control (MIMSC) method is devised to select the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The presented method accounts for the effects that the piezoelectric actuators and the bonding layers have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the MIMSC method and to demonstrate the effect of the physical and geometrical properties of the bonding layer on the dynamic performance of the actively controlled beams. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.
Graf, Jeff; d'Astuto, M.; Jozwiak, C.; Garcia, D.R.; Saini, N.L.; Krisch, M.; Ikeuchi, K.; Baron, A.Q.R.; Eisaki, H.; Lanzara, Alessandra
2008-05-08
We report the first measurement of the Cu-O bond stretching phonon dispersion in optimally doped Bi2Sr1.6La0.4Cu2O6+delta using inelastic x-ray scattering. We found a softening of this phonon at q=(0.25,0,0) from 76 to 60 meV, similar to the one reported in other cuprates. A comparison with angle-resolved photoemission data on the same sample revealed an excellent agreement in terms of energy and momentum between the angle-resolved photoemission nodal kink and the soft part of the bond stretching phonon. Indeed, we find that the momentum space where a 63+-5 meV kink is observed can be connected with a vector q=(xi,0,0) with xi>= 0.22, corresponding exactly to the soft part of the bond stretching phonon.
NASA Astrophysics Data System (ADS)
Thiruvikraman, C.; Balasubramanian, V.; Sridhar, K.
2014-06-01
High velocity oxygen fuel (HVOF)-sprayed cermet coatings are extensively used to combat erosion-corrosion in naval applications and in slurry environments. HVOF spray parameters such as oxygen flow rate, fuel flow rate, powder feed rate, carrier gas flow rate, and spray distance have significant influence on coating characteristics like adhesion bond strength and shear strength. This paper presents the use of statistical techniques in particular response surface methodology (RSM), analysis of variance, and regression analysis to develop empirical relationships to predict adhesion bond strength and lap shear bond strength of HVOF-sprayed WC-CrC-Ni coatings. The developed empirical relationships can be effectively used to predict adhesion bond strength and lap shear bond strength of HVOF-sprayed WC-CrC-Ni coatings at 95% confidence level. Response graphs and contour plots were constructed to identify the optimum HVOF spray parameters to attain maximum bond strength in WC-CrC-Ni coatings.
Ponou, Siméon; Lidin, Sven; Zhang, Yuemei; Miller, Gordon J
2014-05-01
The quaternary phase Ca5Mg0.95Ag1.05(1)Ge5 (3) was synthesized by high-temperature solid-state techniques, and its crystal structure was determined by single-crystal diffraction methods in the orthorhombic space group Pnma-Wyckoff sequence c(12) with a = 23.1481(4) Å, b = 4.4736(1) Å, c = 11.0128(2) Å, V = 1140.43(4) Å(3), Z = 4. The crystal structure can be described as linear intergrowths of slabs cut from the CaGe (CrB-type) and the CaMGe (TiNiSi-type; M = Mg, Ag) structures. Hence, 3 is a hettotype of the hitherto missing n = 3 member of the structure series with the general formula R(2+n)T2X(2+n), previously described with n = 1, 2, and 4. The member with n = 3 was predicted in the space group Cmcm-Wyckoff sequence f(5)c(2). The experimental space group Pnma (in the nonstandard setting Pmcn) corresponds to a klassengleiche symmetry reduction of index two of the predicted space group Cmcm. This transition originates from the switching of one Ge and one Ag position in the TiNiSi-related slab, a process that triggers an uncoupling of each of the five 8f sites in Cmcm into two 4c sites in Pnma. The Mg/Ag site preference was investigated using VASP calculations and revealed a remarkable example of an intermetallic compound for which the electrostatic valency principle is a critical structure-directing force. The compound is deficient by one valence electron according to the Zintl concept, but LMTO electronic structure calculations indicate electronic stabilization and overall bonding optimization in the polyanionic network. Other stability factors beyond the Zintl concept that may account for the electronic stabilization are discussed. PMID:24745932
Ponou, Simeon; Lidin, Sven; Zhang, Yuemei; Miller, Gordon J.
2014-04-18
The quaternary phase Ca5Mg0.95Ag1.05(1)Ge5 (3) was synthesized by high-temperature solid-state techniques, and its crystal structure was determined by single-crystal diffraction methods in the orthorhombic space group Pnma – Wyckoff sequence c12 with a = 23.1481(4) Å, b = 4.4736(1) Å, c = 11.0128(2) Å, V = 1140.43(4) Å3, Z = 4. The crystal structure can be described as linear intergrowths of slabs cut from the CaGe (CrB-type) and the CaMGe (TiNiSi-type; M = Mg, Ag) structures. Hence, 3 is a hettotype of the hitherto missing n = 3 member of the structure series with the general formula R2+nT2X2+n, previously described with n = 1, 2, and 4. The member with n = 3 was predicted in the space group Cmcm – Wyckoff sequence f5c2. The experimental space group Pnma (in the nonstandard setting Pmcn) corresponds to a klassengleiche symmetry reduction of index two of the predicted space group Cmcm. This transition originates from the switching of one Ge and one Ag position in the TiNiSi-related slab, a process that triggers an uncoupling of each of the five 8f sites in Cmcm into two 4c sites in Pnma. The Mg/Ag site preference was investigated using VASP calculations and revealed a remarkable example of an intermetallic compound for which the electrostatic valency principle is a critical structure-directing force. The compound is deficient by one valence electron according to the Zintl concept, but LMTO electronic structure calculations indicate electronic stabilization and overall bonding optimization in the polyanionic network. Other stability factors beyond the Zintl concept that may account for the electronic stabilization are discussed.
Characteristics of hydrogen bond revealed from water clusters
NASA Astrophysics Data System (ADS)
Song, Yan; Chen, Hongshan; Zhang, Cairong; Zhang, Yan; Yin, Yuehong
2014-09-01
The hydrogen bond network is responsible for the exceptional physical and chemical properties of water, however, the description of hydrogen bond remains a challenge for the studies of condensed water. The investigation of structural and binding properties of water clusters provides a key for understanding the H-bonds in bulk water. In this paper, a new set of geometric parameters are defined to describe the extent of the overlap between the bonding orbital of the donor OH and the nonbonding orbital of the lone-pair of the acceptor molecule. This orbital overlap plays a dominant role for the strength of H-bonds. The dependences of the binding energy of the water dimer on these parameters are studied. The results show that these parameters properly describe the H-bond strength. The ring, book, cage and prism isomers of water hexamer form 6, 7, 8 and 9 H-bonds, and the strength of the bonding in these isomers changes markedly. The internally-solvated and the all-surface structures of (H2O) n for n = 17, 19 and 21 are nearly isoenergetic. The internally-solvated isomers form fewer but stronger H-bonds. The hydrogen bonding in the above clusters are investigated in detail. The geometric parameters can well describe the characters of the H-bonds, and they correlate well with the H-bond strength. For the structures forming stronger H-bonds, the H-bond lengths are shorter, the angle parameters are closer to the optimum values, and their rms deviations are smaller. The H-bonds emanating from DDAA and DDA molecules as H-donor are relatively weak. The vibrational spectra of (H2O) n ( n = 17, 19 and 21) are studied as well. The stretching vibration of the intramolecular OH bond is sensitive to its bonding environment. The H-bond strength judged from the geometric parameters is in good agreement with the bonding strength judged from the stretching frequencies.
Pauling bond strength, bond length and electron density distribution
Gibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, M. A.
2014-01-18
A power law regression equation, /r)-0.21, determined for a large number of oxide crystals at ambient conditions and /r)-0.22, determined for geometry optimized hydroxyacid molecules, that connect the bond lengths to the average Pauling electrostatic bond strength, , for the M-O bonded interactions. On the basis of the correspondence between the two sets of equations connecting ?(rc) and the Pauling bond strength s with bond length, it appears that Pauling’s simple definition of bond strength closely mimics the accumulation of the electron density between bonded pairs of atoms. The similarity of the expressions for the crystals and molecules is compelling evidence that the M-O bonded interactions for the crystals and molecules 2 containing the same bonded interactions are comparable. Similar expressions, connecting bond lengths and bond strength, have also been found to hold for fluoride, nitride and sulfide molecules and crystals. The Brown-Shannon bond valence, ?, power law expression ? = [R1/(R(M-O)]N that has found wide use in crystal chemistry, is shown to be connected to a more universal expression determined for oxides and the perovskites, = r[(1.41)/
Geometric PSO + GP = Particle Swarm Programming
Togelius, Julian
Geometric PSO + GP = Particle Swarm Programming Julian Togelius IDSIA USI/SUPSI, Galleria 2, 6928 (PSO) that applies naturally to both continuous and combinatorial spaces. In this paper we apply GPSO Optimization (PSO) is a relatively recently devised population-based stochastic global optimization al- gorithm
Geometric Nelder-Mead Algorithm for the Permutation Representation
Togelius, Julian
optimization, and it is a close relative of Particle Swarm Optimization (PSO) and Differential Evolution (DE). In recent work, PSO, DE and NMA have been generalized using a formal geometric framework that treats rigorously specific PSO, DE and NMA for both continuous and combinatorial spaces retaining the same geometric
Wood, Peter A; Pidcock, Elna; Allen, Frank H
2008-08-01
The occurrence, geometries and energies of hydrogen bonds from N-H and O-H donors to the S acceptors of thiourea derivatives, thioamides and thiones are compared with data for their O analogues - ureas, amides and ketones. Geometrical data derived from the Cambridge Structural Database indicate that hydrogen bonds to the C[double bond]S acceptors are much weaker than those to their C[double bond]O counterparts: van der Waals normalized hydrogen bonds to O are shorter than those to S by approximately 0.25 A. Further, the directionality of the approach of the hydrogen bond with respect to S, defined by the C[double bond]S...H angle, is in the range 102-109 degrees , much lower than the analogous C[double bond]O...H angle which lies in the range 127-140 degrees . Ab initio calculations using intermolecular perturbation theory show good agreement with the experimental results: the differences in hydrogen-bond directionality are closely reproduced, and the interaction energies of hydrogen bonds to S are consistently weaker than those to O, by approximately 12 kJ mol(-1), for each of the three compound classes. There are no CSD examples of hydrogen bonds to aliphatic thiones, (Csp(3))(2)C=S, consistent with the near-equality of the electronegativities of C and S. Thioureas and thioamides have electron-rich N substituents replacing the Csp(3) atoms. Electron delocalization involving C[double bond]S and the N lone pairs then induces a significant >C(delta+)[double bond]S(delta-) dipole, which enables the formation of the medium-strength C[double bond]S...H bonds observed in thioureas and thioamides. PMID:18641451
An Orientation-dependent Hydrogen Bonding Potential Improves Prediction of Specificity and
Morozov, Alexandre V.
An Orientation-dependent Hydrogen Bonding Potential Improves Prediction of Specificity of Washington Box 351560, Seattle WA 98195-1560, USA Hydrogen bonding is a key contributor to the specificity-dependent hydrogen bonding potential based on the geometric characteristics of hydrogen bonds in high
Gieseking, Rebecca L; Risko, Chad; Brédas, Jean-Luc
2015-06-18
Understanding the relationships between the molecular nonlinear optical (NLO) properties and the bond-length alternation (BLA) or ?-bond-order alternation (BOA) along the molecular backbone of linear ?-conjugated systems has proven widely useful in the development of NLO organic chromophores and materials. Here, we examine model polymethines to elucidate the reliability of these relationships. While BLA is solely a measure of molecular geometric structure, BOA includes information pertaining to the electronic structure. As a result, BLA is found to be a good predictor of NLO properties only when optimized geometries are considered, whereas BOA is more broadly applicable. Proper understanding of the distinction between BLA and BOA is critical when designing computational studies of NLO properties, especially for molecules in complex environments or in nonequilibrium geometries. PMID:26266585
Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.
2010-01-01
Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998
Non-hydrogen bond interactions involving the methionine sulfur atom.
Pal, D; Chakrabarti, P
2001-08-01
Of all the nonbonded interactions, hydrogen bond, because of its geometry involving polar atoms, is the most easily recognizable. Here we characterize two interactions involving the divalent sulfur of methionine (Met) residues that do not need any participation of proton. In one an oxygen atom of the main-chain carbonyl group or a carboxylate side chain is used. In another an aromatic atom interacting along the face of the ring is utilized. In these, the divalent sulfur behaves as an electrophile and the other electron-rich atom, a nucleophile. The stereochemistry of the interaction is such that the nucleophile tends to approach approximately along the extension of one of the covalent bonds to S. The nitrogen atom of histidine side chain is extensively used in these nonbonded contacts. There is no particular geometric pattern in the interaction of S with the edge of an aromatic ring, except when an N-H group in involved, which is found within 40 degrees from the perpendicular to the sulfide plane, thus defining the geometry of hydrogen bond interaction involving the sulfur atom. As most of the Met residues which partake in such stereospecific interactions are buried, these would be important for the stability of the protein core, and their incorporation in the binding site would be useful for molecular recognition and optimization of the site's affinity for partners (especially containing aromatic and heteroaromatic groups). Mutational studies aimed at replacing Met by other residues would benefit from the delineation of these interactions. PMID:11565843
Delaney, P. )
1993-10-01
Yankee and Euromarket bonds may soon find their way into the financing of power projects in Latin America. For developers seeking long-term commitments under build, own, operate, and transfer (BOOT) power projects in Latin America, the benefits are substantial.
Deforming geometric transitions
NASA Astrophysics Data System (ADS)
Rossi, Michele
2015-04-01
After a quick review of the wild structure of the complex moduli space of Calabi-Yau 3-folds and the role of geometric transitions in this context (the Calabi-Yau web) the concept of deformation equivalence for geometric transitions is introduced to understand the arrows of the Gross-Reid Calabi-Yau web as deformation-equivalence classes of geometric transitions. Then the focus will be on some results and suitable examples to understand under which conditions it is possible to get simple geometric transitions, which are almost the only well-understood geometric transitions both in mathematics and in physics.
Halogen bonds in crystal engineering: like hydrogen bonds yet different.
Mukherjee, Arijit; Tothadi, Srinu; Desiraju, Gautam R
2014-08-19
The halogen bond is an attractive interaction in which an electrophilic halogen atom approaches a negatively polarized species. Short halogen atom contacts in crystals have been known for around 50 years. Such contacts are found in two varieties: type I, which is symmetrical, and type II, which is bent. Both are influenced by geometric and chemical considerations. Our research group has been using halogen atom interactions as design elements in crystal engineering, for nearly 30 years. These interactions include halogen···halogen interactions (X···X) and halogen···heteroatom interactions (X···B). Many X···X and almost all X···B contacts can be classified as halogen bonds. In this Account, we illustrate examples of crystal engineering where one can build up from previous knowledge with a focus that is provided by the modern definition of the halogen bond. We also comment on the similarities and differences between halogen bonds and hydrogen bonds. These interactions are similar because the protagonist atoms-halogen and hydrogen-are both electrophilic in nature. The interactions are distinctive because the size of a halogen atom is of consequence when compared with the atomic sizes of, for example, C, N, and O, unlike that of a hydrogen atom. Conclusions may be drawn pertaining to the nature of X···X interactions from the Cambridge Structural Database (CSD). There is a clear geometric and chemical distinction between type I and type II, with only type II being halogen bonds. Cl/Br isostructurality is explained based on a geometric model. In parallel, experimental studies on 3,4-dichlorophenol and its congeners shed light on the nature of halogen···halogen interactions and reveal the chemical difference between Cl and Br. Variable temperature studies also show differences between type I and type II contacts. In terms of crystal design, halogen bonds offer a unique opportunity in the strength, atom size and interaction gradation; this may be used in the design of ternary cocrystals. Structural modularity in which an entire crystal structure is defined as a combination of modules is rationalized on the basis of the intermediate strength of a halogen bond. The specific directionality of the halogen bond makes it a good tool to achieve orthogonality in molecular crystals. Mechanical properties can be tuned systematically by varying these orthogonally oriented halogen···halogen interactions. In a further development, halogen bonds are shown to play a systematic role in organization of LSAMs (long range synthon aufbau module), which are bigger structural units containing multiple synthons. With a formal definition in place, this may be the right time to look at differences between halogen bonds and hydrogen bonds and exploit them in more subtle ways in crystal engineering. PMID:25134974
Chakrabarty, Krishnendu
manufacturing yield for 3D ICs, we need to fabricate a number of test pads on the silicon die so consider the pre-bond test-pin-count constraint during optimiza- tion since these pins occupy large silicon area that cannot be used in functional mode. In addition, the proposed test-architecture design takes
NASA Astrophysics Data System (ADS)
Pariona, Moisés Meza; de Oliveira, Fabiane; Teleginski, Viviane; Machado, Siliane; Pinto, Marcio Augusto Villela
2015-07-01
Al-1.5 wt% Fe alloy was irradiate by Yb-fiber laser beam using the laser surface remelting (LSR) technique, generating weld fillets that covered the whole surface of the sample. The laser-treatment showed to be an efficient technology for corrosion resistance improvements. In this study, the finite element method was used to simulate the solidification processes by LSR technique. The method Multigrid was employed in order to reduce the CPU time, which is important to the viability for industrial applications. Multigrid method is a technique very promising of optimization that reduced drastically the CPU time. The result was highly satisfactory, because the CPU time has fallen dramatically in comparison when it was not used Multigrid method. To validate the result of numerical simulation with the experimental result was done the microstructural characterization of laser-treated layer by the optical microscopy and SEM techniques and however, that both results showing be consistent.
Pi Bond Orders and Bond Lengths
ERIC Educational Resources Information Center
Herndon, William C.; Parkanyi, Cyril
1976-01-01
Discusses three methods of correlating bond orders and bond lengths in unsaturated hydrocarbons: the Pauling theory, the Huckel molecular orbital technique, and self-consistent-field techniques. (MLH)
Three-dimensional hydrogen-bond geometry and probability information from a crystal survey
J. E. J. Mills; Philip M. Dean
1996-01-01
An extensive crystal survey of the Cambridge Structural Database has been carried out to provide hydrogen-bond data for use in drug-design strategies. Previous crystal surveys have generated 1D frequency distributions of hydrogen-bond distances and angles, which are not sufficient to model the hydrogen bond as a ligand-receptor interaction. For each hydrogen-bonding group of interest to the drug designer, geometric hydrogen-bond
Ashouri, Mitra; Maghari, Ali; Karimi-Jafari, M H
2015-05-28
Bisphosphonates are important therapeutic agents in bone-related diseases and exhibit complex H-bonding networks. To assess the role of H-bonds in biophosphonate stability, a full conformational search was performed for methylenebisphosphonate (MBP) and 1-hydroxyethylidene-1,1-diphosphonate (HEDP) using the MP2 method in conjunction with the continuum solvation model. The most stable structures and their equilibrium populations were analyzed at two protonation states via assignment of H-bonding motifs to each conformer. Geometrical and topological approaches for the identification and characterization of H-bonds were compared with each other, and some of the important correlations between H-bond features were described over the entire conformational space of a hydroxy-bisphosphonate moiety. The topologically derived H-bond energy obtained from the local density of potential energy at bond critical points shows consistent correlations with other measures such as H-bond frequency shift. An inverse power form without an intercept predicts topological H-bond energies from hydrogen-acceptor distances with an RMS error of less than 1 kcal mol(-1). The consistency of this measure was further checked by building a model that reasonably reproduces the relative stabilities of different conformers from their hydrogen-acceptor distances. In all systems, the predictions of this model are improved by the consideration of weak H-bonds that have no bond critical point. PMID:25920461
ERIC Educational Resources Information Center
Kahn, Steven P.
Fidelity bonds are important for an agency to hold to protect itself against any financial loss that can result from dishonest acts by its employees. Three types of fidelity bonds are available to an agency: (1) public official bonds; (2) dishonesty bonds; and (3) faithful performance bonds. Public official bonds are required by state law to be…
Hirn, Ulrich; Schennach, Robert
2015-01-01
The process of papermaking requires substantial amounts of energy and wood consumption, which contributes to larger environmental costs. In order to optimize the production of papermaking to suit its many applications in material science and engineering, a quantitative understanding of bonding forces between the individual pulp fibers is of importance. Here we show the first approach to quantify the bonding energies contributed by the individual bonding mechanisms. We calculated the impact of the following mechanisms necessary for paper formation: mechanical interlocking, interdiffusion, capillary bridges, hydrogen bonding, Van der Waals forces, and Coulomb forces on the bonding energy. Experimental results quantify the area in molecular contact necessary for bonding. Atomic force microscopy experiments derive the impact of mechanical interlocking. Capillary bridges also contribute to the bond. A model based on the crystal structure of cellulose leads to values for the chemical bonds. In contrast to general believe which favors hydrogen bonding Van der Waals bonds play the most important role according to our model. Comparison with experimentally derived bond energies support the presented model. This study characterizes bond formation between pulp fibers leading to insight that could be potentially used to optimize the papermaking process, while reducing energy and wood consumption. PMID:26000898
NASA Astrophysics Data System (ADS)
Hirn, Ulrich; Schennach, Robert
2015-05-01
The process of papermaking requires substantial amounts of energy and wood consumption, which contributes to larger environmental costs. In order to optimize the production of papermaking to suit its many applications in material science and engineering, a quantitative understanding of bonding forces between the individual pulp fibers is of importance. Here we show the first approach to quantify the bonding energies contributed by the individual bonding mechanisms. We calculated the impact of the following mechanisms necessary for paper formation: mechanical interlocking, interdiffusion, capillary bridges, hydrogen bonding, Van der Waals forces, and Coulomb forces on the bonding energy. Experimental results quantify the area in molecular contact necessary for bonding. Atomic force microscopy experiments derive the impact of mechanical interlocking. Capillary bridges also contribute to the bond. A model based on the crystal structure of cellulose leads to values for the chemical bonds. In contrast to general believe which favors hydrogen bonding Van der Waals bonds play the most important role according to our model. Comparison with experimentally derived bond energies support the presented model. This study characterizes bond formation between pulp fibers leading to insight that could be potentially used to optimize the papermaking process, while reducing energy and wood consumption.
Geometric Reasoning for Automated Planning
NASA Technical Reports Server (NTRS)
Clement, Bradley J.; Knight, Russell L.; Broderick, Daniel
2012-01-01
An important aspect of mission planning for NASA s operation of the International Space Station is the allocation and management of space for supplies and equipment. The Stowage, Configuration Analysis, and Operations Planning teams collaborate to perform the bulk of that planning. A Geometric Reasoning Engine is developed in a way that can be shared by the teams to optimize item placement in the context of crew planning. The ISS crew spends (at the time of this writing) a third or more of their time moving supplies and equipment around. Better logistical support and optimized packing could make a significant impact on operational efficiency of the ISS. Currently, computational geometry and motion planning do not focus specifically on the optimized orientation and placement of 3D objects based on multiple distance and containment preferences and constraints. The software performs reasoning about the manipulation of 3D solid models in order to maximize an objective function based on distance. It optimizes for 3D orientation and placement. Spatial placement optimization is a general problem and can be applied to object packing or asset relocation.
NASA Astrophysics Data System (ADS)
Yin, Zhifu; Qi, Liping; Zou, Helin; Sun, Lei; Xu, Shenbo
2015-08-01
Plastic planar nanofluidic chips are becoming increasingly important for biological and chemical applications. However, the majority of the present bonding methods for planar nanofluidic chips suffer from high dimension loss and low bonding strength. In this work, a novel thermal bonding technique based on O2 plasma and ethanol treatment was proposed. With the assistance of O2 plasma and ethanol, the PET (polyethylene terephthalate) planar nanofluidic chip can be bonded at a low bonding temperature of 50?°C. To increase the bonding rate and bonding strength, the O2 plasma parameters and thermal bonding parameters were optimized during the bonding process. The tensile test indicates that the bonding strength of the PET planar nanofluidic chip can reach 0.954?MPa, while the auto-fluorescence test demonstrates that there is no leakage or blockage in any of the bonded micro- or nanochannels.
NASA Technical Reports Server (NTRS)
1977-01-01
Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.
Exploring New Geometric Worlds
ERIC Educational Resources Information Center
Nirode, Wayne
2015-01-01
When students work with a non-Euclidean distance formula, geometric objects such as circles and segment bisectors can look very different from their Euclidean counterparts. Students and even teachers can experience the thrill of creative discovery when investigating these differences among geometric worlds. In this article, the author describes a…
Reconciling Geometric Planners with
North Carolina at Chapel Hill, University of
Search #12;#12;Manipulation #12;Manipulation Perception Systems Navigation Learning Parallelism Control 3;#12;#12;#12;Physical Manipulation Geometric Search Manipulation Perception Systems Navigation Learning Parallelism-away Sweep #12;Physical Manipulation Geometric Search Manipulation Perception Systems Navigation Learning
Geometrization of Quantum Mechanics
J. F. Carinena; J. Clemente-Gallardo; G. Marmo
2007-03-23
We show that it is possible to represent various descriptions of Quantum Mechanics in geometrical terms. In particular we start with the space of observables and use the momentum map associated with the unitary group to provide an unified geometrical description for the different pictures of Quantum Mechanics. This construction provides an alternative to the usual GNS construction for pure states.
Cis Peptide Bonds in Proteins: Residues Involved, their Conformations, Interactions and Locations
Pal, Debnath
Cis Peptide Bonds in Proteins: Residues Involved, their Conformations, Interactions and Locations bonding and other stabilizing interactions involving cis peptide bonds. This has led to a reclassi®cation of turns mediated by cis peptides, and their average geometrical par- ameters have been evaluated
Harrington, J. Patrick
A Survey of Geometric Algebra and Geometric Calculus c Alan Macdonald Luther College, Decorah, IA is always available at my web page.) The principal argument for the adoption of geometric algebra and Geometric Algebra: http://faculty.luther.edu/~macdonal/laga/ Vector and Geometric Calculus: http
Students' Perceptions of Parental Bonding Styles and Their Academic Burnout
ERIC Educational Resources Information Center
Shin, Hyojung; Lee, Jayoung; Kim, Boyoung; Lee, Sang Min
2012-01-01
This study investigated how parental bonding style affects academic burnout in Korean adolescents. Participants were 447 middle school students, who completed the Parental Bonding Instrument and the Maslach Burnout Inventory-Student Survey. MANCOVA results confirmed that adolescents reporting the optimal bonding parental style, for both mother and…
Technology Transfer Automated Retrieval System (TEKTRAN)
The disaccharide alpha-maltose is a molecular template for amylose. Our previous DFT work on maltose is expanded to a set of 63 fully optimized (B3LYP/6-311++G**) conformations. All clockwise, and counter clockwise hydroxyl groups, as well as 'kink' and band-slip conformers, are studied. Adiabati...
Astrometry without Geometric Distortion
NASA Astrophysics Data System (ADS)
Peng, Qingyu; Wang, Na; Peng, Huanwen; Zhang, Qingfeng; Li, Zhan
2015-08-01
Geometric distortion often exists in an astronomical CCD image even though a long focal length telescope is used. Two algorithms are developed to solve the pattern of geometric distortion and are tested based on many dithering CCD images observed at Yunnan Observatory using the 1 m telescope and 2.4 m telescope. Our results have shown that the astrometry for some moving targets such as an asteroid (Apophis) or a planetary natural satellite (Phoebe) is improved significantly after removing the geometric distortion in each CCD image. The algorithms can be also extended to applying to other telescopes for the purpose of precise astrometry or the check of positional propriety of a telescope.
Esrafili, Mehdi D; Mohammadian-Sabet, Fariba; Solimannejad, Mohammad
2015-04-01
In this work, the interplay between anion-? and pnicogen bond interactions is investigated by ab initio calculations. Cooperative effects are observed in the studied complexes in which anion-? and pnicogen bond interactions coexist. These effects are analyzed in detail in terms of the energetic, geometric, charge-transfer and electron density properties of the complexes. The cooperative energy ranges from -1.8 to -4.1kcalmol(-1). The effect of an anion-? bond on a pnicogen bond is more pronounced than that of a pnicogen bond on an anion-? bond. The enhancing mechanism is analyzed in views with the charge-transfer, electrostatic potential and electron density analysis. PMID:25698102
Geometric ghosts and unitarity
Ne'eman, Y.
1980-09-01
A review is given of the geometrical identification of the renormalization ghosts and the resulting derivation of Unitarity equations (BRST) for various gauges: Yang-Mills, Kalb-Ramond, and Soft-Group-Manifold.
Geometric intrinsic symmetries
Gozdz, A. Szulerecka, A.; Pedrak, A.
2013-08-15
The problem of geometric symmetries in the intrinsic frame of a many-body system (nucleus) is considered. An importance of symmetrization group notion is discussed. Ageneral structure of the intrinsic symmetry group structure is determined.
Geometric Sieving: Automated Distributed Optimization of
Chen, Brian Y.
Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX, 77005, USA 4 Department of Molecular and Human Genetics, Baylor College of Medicine 5 Department. Determining the function of all proteins is a recurring theme in modern biology and medicine, but the sheer
Water filtration optimization by geometric programming
Wray, Duane Jimmy
1970-01-01
filter's 21 typical pattern of performance for a synthetic muddy water after coagulation and settling. A secondary flocculant (polyacrylamide) was also applied immediately ahead of the filter. The addition of such polymers to the filter influent... of separation. Electro- ll kinetic effects are the result of an electric charge on the surface of colloidal particles caused by 1onizat1on or adsorpt1on. Ions are centered around the solid particle 1n alternately charges layers. Electrokinet1c repulsion...
Geometric Optimization in Wireless Communication and Sensing
Katz, Matthew "Matya"
Navigation for Robot Swarms S´andor Fekete 17:1518:00 Discussion and open problem session The Organizers #12 analogues. Cooperative Navigation for Robot Swarms S´andor Fekete In recent years, the field of robotics has and practice of swarm robotics. In particular, we consider online problems related to exploring and surveying
Optimization in Geometric Graphs: Complexity and Approximation
Kahruman-Anderoglu, Sera
2011-02-22
and approximate solutions. In addition, we establish complexity-based theoretical justifications for several greedy heuristics. Unit ball graphs, which are defined in the three dimensional Euclidian space, have several application areas such as computational...
Hierarchies of Geometric Entanglement
M. Blasone; F. Dell'Anno; S. De Siena; F. Illuminati
2008-05-28
We introduce a class of generalized geometric measures of entanglement. For pure quantum states of $N$ elementary subsystems, they are defined as the distances from the sets of $K$-separable states ($K=2,...,N$). The entire set of generalized geometric measures provides a quantification and hierarchical ordering of the different bipartite and multipartite components of the global geometric entanglement, and allows to discriminate among the different contributions. The extended measures are applied to the study of entanglement in different classes of $N$-qubit pure states. These classes include $W$ and $GHZ$ states, and their symmetric superpositions; symmetric multi-magnon states; cluster states; and, finally, asymmetric generalized $W$-like superposition states. We discuss in detail a general method for the explicit evaluation of the multipartite components of geometric entanglement, and we show that the entire set of geometric measures establishes an ordering among the different types of bipartite and multipartite entanglement. In particular, it determines a consistent hierarchy between $GHZ$ and $W$ states, clarifying the original result of Wei and Goldbart that $W$ states possess a larger global entanglement than $GHZ$ states. Furthermore, we show that all multipartite components of geometric entanglement in symmetric states obey a property of self-similarity and scale invariance with the total number of qubits and the number of qubits per party.
NASA Astrophysics Data System (ADS)
Pathak, Biswarup; Umayal, Muthaiah; Jemmis, Eluvathingal D.
The unusual shortness of the bond length in several main group and transition metal compounds is explained on the basis of their ?-alone bonding. The detailed electronic structure calculation on C2, HBBH, and Fe2(CO)6 shows that each of them has two ?-alone bonds (unsupported by an underlying ?-bond), whereas B2 has two-half ?-bonds. The C-C bond length in C2 is 1.240 Å, shorter than any C-C double (? + ?, in C2H4, C-C=1.338 Å) bonded species. The B-B bond distance in B2 (1.590 Å, two half-? bonds) is shorter than any B-B single ?-bonded (~1.706 Å) species. The calculated Fe-Fe bond distance of 2.002 Å in Fe2(CO)6 is shorter than those of some experimentally known M-M single bonded compounds in the range of 2.904-3.228 Å. Here, our detailed studies on the second and third row diatomics (five, six, seven and eight valence electrons species) and transition metal complexes show that ?-alone bonds left to themselves are shorter than ?-bonds; in many ways, ?-bonds prevent ?-bonds from adopting their optimal shorter distances.
Tetrel bond-?-hole bond as a preliminary stage of the SN2 reaction.
Grabowski, S?awomir J
2014-02-01
MP2/aug-cc-pVTZ calculations were carried out on complexes of ZH4, ZFH3 and ZF4 (Z = C, Si and Ge) molecules with HCN, LiCN and Cl(-) species acting as Lewis bases through nitrogen centre or chlorine ion. Z-Atoms in these complexes usually act as Lewis acid centres forming ?-hole bonds with Lewis bases. Such noncovalent interactions may adopt a name of tetrel bonds since they concern the elements of the group IV. There are exceptions for complexes of CH4 and CF4, as well as for the F4SiNCH complex where the tetrel bond is not formed. The energetic and geometrical parameters of the complexes were analyzed and numerous correlations between them were found. The Quantum Theory of 'Atoms in Molecules' and Natural Bonds Orbital (NBO) method used here should deepen the understanding of the nature of the tetrel bond. An analysis of the electrostatic potential surfaces of the interacting species is performed. The electron charge redistribution, being the result of the tetrel bond formation, is the same as that of the SN2 reaction. The energetic and geometrical parameters of the complexes analyzed here correspond to different stages of the SN2 process. PMID:24296531
Geometric Differential Evolution for Combinatorial and Programs Spaces
Kent, University of
relatively recent additions to the Evolutionary Al- gorithms (EAs) family are Particle Swarm Optimization (PSO) [5], inspired to the flocking behavior of swarms of A. Moraglio is with the School of Computing for the target space and for the target representation. GDE is related to Geometric Particle Swarm Optimization
Gaussian states and geometrically uniform symmetry
Gianfranco Cariolaro; Roberto Corvaja; Gianfranco Pierobon
2014-10-20
Quantum Gaussian states can be considered as the majority of the practical quantum states used in quantum communications and more generally in quantum information. Here we consider their properties in relation with the geometrically uniform symmetry, a property of quantum states that greatly simplifies the derivation of the optimal decision by means of the square root measurements. In a general framework of the $N$-mode Gaussian states we show the general properties of this symmetry and the application of the optimal quantum measurements. An application example is presented, to quantum communication systems employing pulse position modulation. We prove that the geometrically uniform symmetry can be applied to the general class of multimode Gaussian states.
Wave Function as Geometric Entity
NASA Astrophysics Data System (ADS)
Lev, Bohdan I.
A new approach to the geometrization of the electron theory is proposed. The particle wave function is represented by a geometric entity, i.e., Clifford number, with the translation rules possessing the structure of Dirac equation for any manifold. A solution of this equation is obtained in terms of geometric treatment. Interference of electrons whose wave functions are represented by geometric entities is considered. New experiments concerning the geometric nature of electrons are proposed.
An alternative near-neighbor definition of hydrogen bonding in water.
Hammerich, A D; Buch, V
2008-03-21
A definition of hydrogen bonding in water is proposed in which an H...O pair forms a hydrogen bond if (a) an oxygen atom is the nearest nonchemically bonded neighbor of a hydrogen atom; and (b) the hydrogen is the first or the second intermolecular near-neighbor of the oxygen. Unlike the commonly employed hydrogen-bond definitions, this definition does not depend on the choice of geometric or energetic cutoffs applied to continuous distributions of properties. With the present definition, the distribution of O...H bond lengths decays smoothly to zero in a physically reasonable range. After correction for the presence of intermittent hydrogen bonds, this definition appears to provide a more stable description of hydrogen bonds and coordination shells than the more conventional cutoff-based definition. "Partial" H bonds satisfying only one of the two bonding requirements serve as transition states in the H-bond network evolution. PMID:18361545
Geometrical optical illusionists.
Wade, Nicholas J
2014-01-01
Geometrical optical illusions were given this title by Oppel in 1855. Variants on such small distortions of visual space were illustrated thereafter, many of which bear the names of those who first described them. Some original forms of the geometrical optical illusions are shown together with 'perceptual portraits' of those who described them. These include: Roget, Chevreul, Fick, Zöllner, Poggendorff, Hering, Kundt, Delboeuf Mach, Helmholtz, Hermann, von Bezold, Müller-Lyer, Lipps, Thiéry, Wundt, Münsterberg, Ebbinghaus, Titchener, Ponzo, Luckiesh, Sander, Ehrenstein, Gregory, Heard, White, Shepard, and. Lingelbach. The illusions are grouped under the headings of orientation, size, the combination of size and orientation, and contrast. Early theories of illusions, before geometrical optical illusions were so named, are mentioned briefly. PMID:25507310
Inflation from geometrical tachyons
Thomas, Steven; Ward, John [Department of Physics, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)
2005-10-15
We propose an alternative formulation of tachyon inflation using the geometrical tachyon arising from the time dependent motion of a BPS D3-brane in the background geometry due to k parallel NS5-branes arranged around a ring of radius R. Because of the fact that the mass of this geometrical tachyon field is {radical}(2/k) times smaller than the corresponding open-string tachyon mass, we find that the slow-roll conditions for inflation and the number of e-foldings can be satisfied in a manner that is consistent with an effective 4-dimensional model and with a perturbative string coupling. We also show that the metric perturbations produced at the end of inflation can be sufficiently small and do not lead to the inconsistencies that plague the open-string tachyon models. Finally we argue for the existence of a minimum of the geometrical tachyon potential which could give rise to a traditional reheating mechanism.
Inflation from Geometrical Tachyons
Steven Thomas; John Ward
2005-10-04
We propose an alternative formulation of tachyon inflation using the geometrical tachyon arising from the time dependent motion of a BPS $D3$-brane in the background geometry due to $k$ parallel $NS$5-branes arranged around a ring of radius $R $. Due to the fact that the mass of this geometrical tachyon field is $\\sqrt{2/k} $ times smaller than the corresponding open-string tachyon mass, we find that the slow roll conditions for inflation and the number of e-foldings can be satisfied in a manner that is consistent with an effective 4-dimensional model and with a perturbative string coupling. We also show that the metric perturbations produced at the end of inflation can be sufficiently small and do not lead to the inconsistencies that plague the open string tachyon models. Finally we argue for the existence of a minimum of the geometrical tachyon potential which could give rise to a traditional reheating mechanism.
Geometrical optical illusionists.
Wade, Nicholas J
2014-01-01
Geometrical optical illusions were given this title by Oppel in 1855. Variants on such small distortions of visual space were illustrated thereafter, many of which bear the names of those who first described them. Some original forms of the geometrical optical illusions are shown together with 'perceptual portraits' of those who described them. These include: Roget, Chevreul, Fick, Zöllner, Poggendorff, Hering, Kundt, Delboeuf Mach, Helmholtz, Hermann, von Bezold, Müller-Lyer, Lipps, Thiéry, Wundt, Münsterberg, Ebbinghaus, Titchener, Ponzo, Luckiesh, Sander, Ehrenstein, Gregory, Heard, White, Shepard, and. Lingelbach. The illusions are grouped under the headings of orientation, size, the combination of size and orientation, and contrast. Early theories of illusions, before geometrical optical illusions were so named, are mentioned briefly. PMID:25420326
Inflation from geometrical tachyons
NASA Astrophysics Data System (ADS)
Thomas, Steven; Ward, John
2005-10-01
We propose an alternative formulation of tachyon inflation using the geometrical tachyon arising from the time dependent motion of a BPS D3-brane in the background geometry due to k parallel NS5-branes arranged around a ring of radius R. Because of the fact that the mass of this geometrical tachyon field is 2/k times smaller than the corresponding open-string tachyon mass, we find that the slow-roll conditions for inflation and the number of e-foldings can be satisfied in a manner that is consistent with an effective 4-dimensional model and with a perturbative string coupling. We also show that the metric perturbations produced at the end of inflation can be sufficiently small and do not lead to the inconsistencies that plague the open-string tachyon models. Finally we argue for the existence of a minimum of the geometrical tachyon potential which could give rise to a traditional reheating mechanism.
NSDL National Science Digital Library
Investing in Bonds was created by the Bond Market Association to educate investors about the benefits of bonds investing. The Investor's Guide to Bond Basics educates investors about the types of bonds available, criteria for evaluating a bond, a guide to buying bonds, bond investment strategies and a glossary of bond market terms. The Bond Market section provides an overview of the U.S. bond market while the Investor's Checklist section takes the investor step-by-step through the bond investment decision process. Investors will also find sections with information on municipal bonds, corporate bonds, mortgage securities and U.S. Inflation-Indexed Securities.
A comparison of polarization and bond functions for density functional calculations
Helgaker, Trygve
A comparison of polarization and bond functions for density functional calculations JESPER BRUUN1 calculations is analyzed by comparing nuclear centred polarization functions with bond functions placed optimization of the exponents of the polarization and bond functions. While addition of bond functions can
NASA Technical Reports Server (NTRS)
Shahshahani, M.
1991-01-01
The performance characteristics are discussed of certain algebraic geometric codes. Algebraic geometric codes have good minimum distance properties. On many channels they outperform other comparable block codes; therefore, one would expect them eventually to replace some of the block codes used in communications systems. It is suggested that it is unlikely that they will become useful substitutes for the Reed-Solomon codes used by the Deep Space Network in the near future. However, they may be applicable to systems where the signal to noise ratio is sufficiently high so that block codes would be more suitable than convolutional or concatenated codes.
Hydrogen-bond dynamics for the extended simple point-charge model of water Francis W. Starr,1,
Stanley, H. Eugene
Hydrogen-bond dynamics for the extended simple point-charge model of water Francis W. Starr,1 1999; revised manuscript received 22 February 2000 We study hydrogen-bond dynamics in liquid water and geometric definitions of a hydrogen bond, and employ two analysis methods: i a history-dependent correlation
Oxidative addition of the C-I bond on aluminum nanoclusters
NASA Astrophysics Data System (ADS)
Sengupta, Turbasu; Das, Susanta; Pal, Sourav
2015-07-01
Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly sensitive to the geometrical shapes and electronic structures of the clusters rather than their size, imposing the fact that comprehensive studies on aluminum clusters can be beneficial for nanoscience and nanotechnology. To understand the possible reaction mechanism in detail, the reaction pathway is investigated with the ab initio Born Oppenheimer Molecular Dynamics (BOMD) simulation and the Natural Bond Orbital (NBO) analysis. In short, our theoretical study highlights the thermodynamic and kinetic details of C-I bond dissociation on aluminum clusters for future endeavors in cluster chemistry.Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly sensitive to the geometrical shapes and electronic structures of the clusters rather than their size, imposing the fact that comprehensive studies on aluminum clusters can be beneficial for nanoscience and nanotechnology. To understand the possible reaction mechanism in detail, the reaction pathway is investigated with the ab initio Born Oppenheimer Molecular Dynamics (BOMD) simulation and the Natural Bond Orbital (NBO) analysis. In short, our theoretical study highlights the thermodynamic and kinetic details of C-I bond dissociation on aluminum clusters for future endeavors in cluster chemistry. Electronic supplementary information (ESI) available: Cartesian coordinates for the optimized structures and harmonic frequencies, sample IRC data and plot, grid data for three dimensional potential energy surface and contour plot and data for BOMD simulation. See DOI: 10.1039/c5nr02278a
NASA Technical Reports Server (NTRS)
Gwo, Dz-Hung (Inventor)
2003-01-01
A method of bonding substrates by hydroxide-catalyzed hydration/dehydration involves applying a bonding material to at least one surface to be bonded, and placing the at least one surface sufficiently close to another surface such that a bonding interface is formed between them. A bonding material of the invention comprises a source of hydroxide ions, and may optionally include a silicate component, a particulate filling material, and a property-modifying component. Bonding methods of the invention reliably and reproducibly provide bonds which are strong and precise, and which may be tailored according to a wide range of possible applications. Possible applications for bonding materials of the invention include: forming composite materials, coating substrates, forming laminate structures, assembly of precision optical components, and preparing objects of defined geometry and composition. Bonding materials and methods of preparing the same are also disclosed.
Lin, Ming C.
Geometric Sound Propagation Micah Taylor #12;Sound propagation Given a sound source in a scene arrive at the listener #12;Sound propagation Sound travels slow 344 m/s Specular reflections Perfect reflection Diffraction Sounds `bends' around corners #12;Sound propagation Doppler effect Change in frequency
1500 System Geometric Dictionary.
ERIC Educational Resources Information Center
Peloquin, Paul V.
A general description is provided of the "geometric dictionary," a graphic display aid, used by the Computer-Assisted Instruction Laboratory at the Pennsylvania State University. The purpose of the description is to enable the reader to duplicate and use the dictionary on any cathode ray tube terminal of the IBM 1500 system. The major advantages…
ERIC Educational Resources Information Center
Burgess, Claudia R.
2014-01-01
Designed for a broad audience, including educators, camp directors, afterschool coordinators, and preservice teachers, this investigation aims to help individuals experience mathematics in unconventional and exciting ways by engaging them in the physical activity of building geometric shapes using ropes. Through this engagement, the author…
NASA Technical Reports Server (NTRS)
Ives, David
1995-01-01
This paper presents a highly automated hexahedral grid generator based on extensive geometrical and solid modeling operations developed in response to a vision of a designer-driven one day turnaround CFD process which implies a designer-driven one hour grid generation process.
Geometric Series via Probability
ERIC Educational Resources Information Center
Tesman, Barry
2012-01-01
Infinite series is a challenging topic in the undergraduate mathematics curriculum for many students. In fact, there is a vast literature in mathematics education research on convergence issues. One of the most important types of infinite series is the geometric series. Their beauty lies in the fact that they can be evaluated explicitly and that…
Pragmatic geometric model evaluation
NASA Astrophysics Data System (ADS)
Pamer, Robert
2015-04-01
Quantification of subsurface model reliability is mathematically and technically demanding as there are many different sources of uncertainty and some of the factors can be assessed merely in a subjective way. For many practical applications in industry or risk assessment (e. g. geothermal drilling) a quantitative estimation of possible geometric variations in depth unit is preferred over relative numbers because of cost calculations for different scenarios. The talk gives an overview of several factors that affect the geometry of structural subsurface models that are based upon typical geological survey organization (GSO) data like geological maps, borehole data and conceptually driven construction of subsurface elements (e. g. fault network). Within the context of the trans-European project "GeoMol" uncertainty analysis has to be very pragmatic also because of different data rights, data policies and modelling software between the project partners. In a case study a two-step evaluation methodology for geometric subsurface model uncertainty is being developed. In a first step several models of the same volume of interest have been calculated by omitting successively more and more input data types (seismic constraints, fault network, outcrop data). The positions of the various horizon surfaces are then compared. The procedure is equivalent to comparing data of various levels of detail and therefore structural complexity. This gives a measure of the structural significance of each data set in space and as a consequence areas of geometric complexity are identified. These areas are usually very data sensitive hence geometric variability in between individual data points in these areas is higher than in areas of low structural complexity. Instead of calculating a multitude of different models by varying some input data or parameters as it is done by Monte-Carlo-simulations, the aim of the second step of the evaluation procedure (which is part of the ongoing work) is to calculate basically two model variations that can be seen as geometric extremes of all available input data. This does not lead to a probability distribution for the spatial position of geometric elements but it defines zones of major (or minor resp.) geometric variations due to data uncertainty. Both model evaluations are then analyzed together to give ranges of possible model outcomes in metric units.
Imperfect Geometric Control and Overdamping for The Damped Wave Equation
NASA Astrophysics Data System (ADS)
Burq, Nicolas; Christianson, Hans
2015-05-01
We consider the damped wave equation on a manifold with imperfect geometric control. We show the sub-exponential energy decay estimate in (Christianson, J Funct Anal 258(3):1060-1065, 2010) is optimal in the case of one hyperbolic periodic geodesic. We show if the equation is overdamped, then the energy decays exponentially. Finally we show if the equation is overdamped but geometric control fails for one hyperbolic periodic geodesic, then nevertheless the energy decays exponentially.
Stanford University
Optimization Euclidean Distance Geometry 2 Moo Publishing #12;Meboo Publishing USA PO Box 12 Palo Alto, California 94302 Dattorro, Convex Optimization Euclidean Distance Geometry, second edition, Moo, v2015 but limited to personal use. 2005-2015 Moo Publishing USA #12;for Jennie Columba Antonio & Sze Wan #12;EDM
NSDL National Science Digital Library
The Bond Market Association "represents securities firms and banks that underwrite, trade and sell debt securities." Their web site is divided into several sections. The Research Desk presents the results of research conducted by the association, including forecasts of economic growth and analysis of bond market trends. The Legislative Issues and Regulatory sections provide a summary of legislative and regulatory developments of interest to the bond market community. Market Practices contains guidelines and procedures to be followed in the bond market. The site also provides information to investors on how to invest in corporate bonds, tax-exempt municipal bonds, and mortgage securities.
PREFACE: Geometrically frustrated magnetism Geometrically frustrated magnetism
NASA Astrophysics Data System (ADS)
Gardner, Jason S.
2011-04-01
Frustrated magnetism is an exciting and diverse field in condensed matter physics that has grown tremendously over the past 20 years. This special issue aims to capture some of that excitement in the field of geometrically frustrated magnets and is inspired by the 2010 Highly Frustrated Magnetism (HFM 2010) meeting in Baltimore, MD, USA. Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry based on triangles and tetrahedra. Most studies have centred around the kagomé and pyrochlore based magnets but recent work has looked at other structures including the delafossite, langasites, hyper-kagomé, garnets and Laves phase materials to name a few. Personally, I hope this issue serves as a great reference to scientist both new and old to this field, and that we all continue to have fun in this very frustrated playground. Finally, I want to thank the HFM 2010 organizers and all the sponsors whose contributions were an essential part of the success of the meeting in Baltimore. Geometrically frustrated magnetism contents Spangolite: an s = 1/2 maple leaf lattice antiferromagnet? T Fennell, J O Piatek, R A Stephenson, G J Nilsen and H M Rønnow Two-dimensional magnetism and spin-size effect in the S = 1 triangular antiferromagnet NiGa2S4 Yusuke Nambu and Satoru Nakatsuji Short range ordering in the modified honeycomb lattice compound SrHo2O4 S Ghosh, H D Zhou, L Balicas, S Hill, J S Gardner, Y Qi and C R Wiebe Heavy fermion compounds on the geometrically frustrated Shastry-Sutherland lattice M S Kim and M C Aronson A neutron polarization analysis study of moment correlations in (Dy0.4Y0.6)T2 (T = Mn, Al) J R Stewart, J M Hillier, P Manuel and R Cywinski Elemental analysis and magnetism of hydronium jarosites—model kagome antiferromagnets and topological spin glasses A S Wills and W G Bisson The Herbertsmithite Hamiltonian: ?SR measurements on single crystals Oren Ofer, Amit Keren, Jess H Brewer, Tianheng H Han and Young S Lee Classical topological order in kagome ice Andrew J Macdonald, Peter C W Holdsworth and Roger G Melko Magnetic phase diagrams of classical triangular and kagome antiferromagnets M V Gvozdikova, P-E Melchy and M E Zhitomirsky The ordering of XY spin glasses Hikaru Kawamura Dynamic and thermodynamic properties of the generalized diamond chain model for azurite Andreas Honecker, Shijie Hu, Robert Peters and Johannes Richter Classical height models with topological order Christopher L Henley A search for disorder in the spin glass double perovskites Sr2CaReO6 and Sr2MgReO6 using neutron diffraction and neutron pair distribution function analysis J E Greedan, Shahab Derakhshan, F Ramezanipour, J Siewenie and Th Proffen Order and disorder in the local and long-range structure of the spin-glass pyrochlore, Tb2Mo2O7 Yu Jiang, Ashfia Huq, Corwin H Booth, Georg Ehlers, John E Greedan and Jason S Gardner The magnetic phase diagram of Gd2Sn2O7 R S Freitas and J S Gardner Calculation of the expected zero-field muon relaxation rate in the geometrically frustrated rare earth pyrochlore Gd2Sn2O7 antiferromagnet P A McClarty, J N Cosman, A G Del Maestro and M J P Gingras Magnetic frustration in the disordered pyrochlore Yb2GaSbO7 J A Hodges, P Dalmas de Réotier, A Yaouanc, P C M Gubbens, P J C King and C Baines Titanium pyrochlore magnets: how much can be learned from magnetization measurements? O A Petrenko, M R Lees and G Balakrishnan Local susceptibility of the Yb2Ti2O7 rare earth pyrochlore computed from a Hamiltonian with anisotropic exchange J D Thompson, P A McClarty and M J P Gingras Slow and static spin correlations in Dy2 + xTi2 - xO7 - ? J S Gardner, G Ehlers, P Fouquet, B Farago and J R Stewart The spin ice Ho2Ti2O7 versus the spin liquid Tb2Ti2O7: field-induced magnetic structures A P Sazonov, A Gukasov and I Mirebeau Magnetic monopole dynamics in spin ice L D C Jaubert and P C W Holdsworth
NASA Astrophysics Data System (ADS)
Zhou, Pan-Pan; Qiu, Wen-Yuan
2009-08-01
Standard Watson-Crick adenine-thymine (AT) base pair has been investigated by using the B3LYP functional with 6-31G(d, p) basis set, at which level of theory the geometrical characteristics of the AT base pair are the best in agreement with the experiment. It exhibits simultaneously red-shifted N-H···O and N-H···N hydrogen bonds as well as a blue-shifted C-H···O contact. AIM analysis suggests that the blue-shifted C-H···O contact exists as van der Waals interaction, and the electron density ? that reflects the strength of a bond has been used to explain the red- and blue-shifted. By means of NBO analysis, we report a method to estimate the effect of hyperconjugation quantitatively, which combines the electron density in the X-H (X = N, C) ? bonding orbital with that in the ?* antibonding orbital. The effect of structural reorganization on the origins of the red- and blue-shifted has been considered by the partial optimization, its behavior on the X-H (X = N, C) bond is quite different. Rehybridization and repolarization models are employed, and they act as bond-shortening effects. The competition between the electrostatic attractions and Pauli/nucleus repulsions is present in the two typical red-shifted N-H···O and N-H···N hydrogen bonds as well as in the blue-shifted C-H···O van der Waals contact. Electrostatic attraction between H and Y atoms (Y = O, N) is an important reason for the red shift, while the nucleus-nucleus repulsion between H and O atoms may be a factor leading to the C-H bond contraction and its blue shift. The electric field effect induced by the acceptor O atom on the C-H bond is also discussed.
Geometric diffusion of quantum trajectories
NASA Astrophysics Data System (ADS)
Yang, Fan; Liu, Ren-Bao
2015-07-01
A quantum object can acquire a geometric phase (such as Berry phases and Aharonov–Bohm phases) when evolving along a path in a parameter space with non-trivial gauge structures. Inherent to quantum evolutions of wavepackets, quantum diffusion occurs along quantum trajectories. Here we show that quantum diffusion can also be geometric as characterized by the imaginary part of a geometric phase. The geometric quantum diffusion results from interference between different instantaneous eigenstate pathways which have different geometric phases during the adiabatic evolution. As a specific example, we study the quantum trajectories of optically excited electron-hole pairs in time-reversal symmetric insulators, driven by an elliptically polarized terahertz field. The imaginary geometric phase manifests itself as elliptical polarization in the terahertz sideband generation. The geometric quantum diffusion adds a new dimension to geometric phases and may have applications in many fields of physics, e.g., transport in topological insulators and novel electro-optical effects.
Geometric diffusion of quantum trajectories.
Yang, Fan; Liu, Ren-Bao
2015-01-01
A quantum object can acquire a geometric phase (such as Berry phases and Aharonov-Bohm phases) when evolving along a path in a parameter space with non-trivial gauge structures. Inherent to quantum evolutions of wavepackets, quantum diffusion occurs along quantum trajectories. Here we show that quantum diffusion can also be geometric as characterized by the imaginary part of a geometric phase. The geometric quantum diffusion results from interference between different instantaneous eigenstate pathways which have different geometric phases during the adiabatic evolution. As a specific example, we study the quantum trajectories of optically excited electron-hole pairs in time-reversal symmetric insulators, driven by an elliptically polarized terahertz field. The imaginary geometric phase manifests itself as elliptical polarization in the terahertz sideband generation. The geometric quantum diffusion adds a new dimension to geometric phases and may have applications in many fields of physics, e.g., transport in topological insulators and novel electro-optical effects. PMID:26178745
Bao, Jack (Jack C.)
2009-01-01
This thesis consists of three empirical essays on corporate bonds, examining the role of both credit risk and liquidity. In the first chapter, I test the ability of structural models of default to price corporate bonds in ...
MESHLESS GEOMETRIC SUBDIVISION Carsten Moenning
MESHLESS GEOMETRIC SUBDIVISION By Carsten Moenning Facundo M´emoli Guillermo Sapiro Nira Dyn0436 Phone: 612/624-6066 Fax: 612/626-7370 URL: http://www.ima.umn.edu #12;Meshless Geometric Subdivision by introducing the notion of meshless, or point cloud, geometric subdivision. Our meshless subdivision approach
Multigrid Geometric Active Contour Models
George Papandreou; Petros Maragos
2007-01-01
ó Geometric active contour models are very popular PDE tools in image analysis and computer vision. We present a new multigrid algorithm for the fast evolution of level set- based geometric active contours and compare it with other established numerical schemes. We overcome the main bottleneck associated with most numerical implementations of geometric active contours, namely the need for very
Geometric Solids and Their Properties
NSDL National Science Digital Library
Illuminations; National Council of Teachers of Mathematics (NCTM)
2000-01-01
Explore geometric solids and their properties with these interactive tools, beginning with an introduction to the faces of basic polyhedra; counting the number of faces, edges, and corners (vertices) in various solids; discovering Euler's Formula; constructing physical models of geometric solids; and identifying which geometric solids can be made from given nets.
A geometric definition of mass
NASA Astrophysics Data System (ADS)
González-Martin, Gustavo
1994-12-01
An invariant definition of mass is given, within the context of a geometric unified theory, in terms of the geometric connection and the matter current. This geometric mass corresponds to the concept of self energy and leads to the mass parameter in Dirac's equation.
Limits: Geometric and Harmonic Series
NSDL National Science Digital Library
Illuminations National Council of Teachers of Mathematics
2010-05-26
A geometric series is a sum of numbers such that the ratio between consecutive terms is constant. For instance, 1/2 + 1/4 + 1/8 + … is a geometric series. In this resource you can set up various geometric series and see a visual representation of the successive terms and the corresponding sum of those terms.
The rotational spectrum and geometrical structure of thiozone, S3.
McCarthy, Michael C; Thorwirth, Sven; Gottlieb, Carl A; Thaddeus, Patrick
2004-04-01
The rotational spectrum of thiozone, S3, has been observed for the first time. From the rotational constants of the normal and 34S isotopic species, a precise geometrical structure has been derived: S3 is a bent chain with a bond to the apex S of length 1.917(1) A and an apex angle of 117.36(6) degrees . The derived structural parameters indicate substantial double-bonding character in S3 and sp2 hybridization of the central sulfur atom. Thiozone is an excellent candidate for astronomical detection in the atmosphere of Io, the innermost Galilean moon of Jupiter, and in rich interstellar sources. PMID:15053585
Causal And Geometric Relations
Shrader, Douglas W. Jr.
CAUSAL AND GEOMETRIC RELATIONS* Douglas W. Shrader, Jr. Is space curved? The discovery of Non-Euclidean geometries inspired several attempts to determine empirically the topology of physical space. Hans Reichenbach recognized that a number... of causal principles are presupposed in these experiments and suggested that, for geometry to be an empirical matter, we have to intro duce the requirement that no causal relations are vio lated (that there are no causal anomalies). Though objectionable...
Geometrical deuteron stripping revisited
Neoh, Y. S.; Yap, S. L. [Plasma Research Technology Center, University of Malaya, 50603 Kuala Lumpur (Malaysia)
2014-03-05
We investigate the reality of the idea of geometrical deuteron stripping originally envisioned by Serber. By taking into account of realistic deuteron wavefunction, nuclear density, and nucleon stopping mean free path, we are able to estimate inclusive deuteron stripping cross section for deuteron energy up to before pion production. Our semiclassical model contains only one global parameter constant for all nuclei which can be approximated by Woods-Saxon or any other spherically symmetric density distribution.
Rapid adhesive bonding concepts
NASA Technical Reports Server (NTRS)
Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.
1984-01-01
Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.
Wouters, J.M.; Doe, P.J.
1991-02-01
The tensile strength of bonded acrylic is tested as a function of bond joint thickness. 0.125 in. thick bond joints were found to posses the maximum strength while the acceptable range of joints varied from 0.063 in. to almost 0.25 in. Such joints are used in the Sudbury Neutrino Observatory.
30 CFR 281.33 - Bonds and bonding requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... false Bonds and bonding requirements. 281.33 Section 281...THE INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL...281.33 Bonds and bonding requirements. (a) When the leasing notice specifies...
Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations
NASA Technical Reports Server (NTRS)
Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin
2000-01-01
A methodology is presented for determining the fatigue life of bonded composite skin/stringer structures based on delamination fatigue characterization data and geometric nonlinear finite element analyses. Results were compared to fatigue tests on stringer flange/skin specimens to verify the approach.
Carlsson, Anna-Carin C; Veiga, Alberte X; Erdélyi, Máté
2015-01-01
Because of its expected applicability for modulation of molecular recognition phenomena in chemistry and biology, halogen bonding has lately attracted rapidly increasing interest. As most of these processes proceed in solution, the understanding of the influence of solvents on the interaction is of utmost importance. In addition, solution studies provide fundamental insights into the nature of halogen bonding, including, for example, the relative importance of charge transfer, dispersion, and electrostatics forces. Herein, a selection of halogen bonding literature is reviewed with the discussion focusing on the solvent effect and the electronic characteristics of halogen bonded complexes. Hence, charged and neutral systems together with two- and three-center bonds are presented in separate sub-sections. Solvent polarity is shown to have a slight stabilizing effect on neutral, two-center halogen bonds while strongly destabilizes charged, two-center complexes. It does not greatly influence the geometry of three-center halogen bonds, even though polar solvents facilitate dissociation of the counter-ion of charged three-center bonds. The charged three-center bonds are strengthened by increased environment polarity. Solvents possessing hydrogen bond donor functionalities efficiently destabilize all types of halogen bonds, primarily because of halogen vs hydrogen bond competition. A purely electrostatic model is insufficient for the description of halogen bonds in polar systems whereas it may give reasonable correlation to experimental data obtained in noninteracting, apolar solvents. Whereas dispersion plays a significant role for neutral, two-center halogen bonds, charged halogen bond complexes possess a significant charge transfer characteristic. PMID:25805141
Johnson, Jason; Polk, Wade
2002-08-12
pay taxes each year on the interest as it accrues, even though you haven?t received the money. 6. High-yield or junk bonds High-yield or junk bonds are debt obligations issued by emerg- ing companies or by established companies that have fallen on hard...-dominated portfolio; for those in retirement, it will provide money to live on. Getting that steady income often entails investing in bonds. Bonds are debt instruments issued by a corporation or a government (fed- eral, state or municipal). When you buy a bond, you...
Bonding thermoplastic polymers
Wallow, Thomas I. (Fremont, CA); Hunter, Marion C. (Livermore, CA); Krafcik, Karen Lee (Livermore, CA); Morales, Alfredo M. (Livermore, CA); Simmons, Blake A. (San Francisco, CA); Domeier, Linda A. (Danville, CA)
2008-06-24
We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.
Hydrophobic silicon wafer bonding
NASA Astrophysics Data System (ADS)
Tong, Q.-Y.; Schmidt, E.; Gösele, U.; Reiche, M.
1994-01-01
Wafers prepared by an HF dip without a subsequent water rinse were bonded at room temperature and annealed at temperatures up to 1100 °C. Based on substantial differences between bonded hydrophilic and hydrophobic Si wafer pairs in the changes of the interface energy with respect to temperature, secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM), we suggest that hydrogen bonding between Si-F and H-Si across two mating wafers is responsible for room temperature bonding of hydrophobic Si wafers. The interface energy of the bonded hydrophobic Si wafer pairs does not change appreciably with time up to 150 °C. This stability of the bonding interface makes reversible room-temperature hydrophobic wafer bonding attractive for the protection of silicon wafer surfaces.
Micromorphology of the bonded dentin interface and its relationship to bond strength.
Gwinnett, A J; Kanca, J A
1992-04-01
This study demonstrated a relationship between shear bond strength and the formation of a "hybrid" layer associated with the infiltration of resin into the conditioned dentin. The wetness of the substrate was also shown to influence shear bond strength with a statistically significant increase in bond strength when the tissue was blot dried. The increase was attributed to the strongly hydrophilic nature of the acetone-containing primer in the test system. Since a hybrid zone has been demonstrated in vivo and its presence has been linked to a gap-free restoration interface, it is clinically relevant to pursue systems which embody this concept. The manuscript describes methods and systems which can optimize bond strength to dentin, especially wet dentin with bond strengths equal to or better than those recorded for enamel. The method portends a high order of significance and justification for clinical evaluation. Water-loving hydrophilic systems are well suited to naturally hydrated dentin encountered clinically. PMID:1524750
System analysis through bond graph modeling
NASA Astrophysics Data System (ADS)
McBride, Robert Thomas
2005-07-01
Modeling and simulation form an integral role in the engineering design process. An accurate mathematical description of a system provides the design engineer the flexibility to perform trade studies quickly and accurately to expedite the design process. Most often, the mathematical model of the system contains components of different engineering disciplines. A modeling methodology that can handle these types of systems might be used in an indirect fashion to extract added information from the model. This research examines the ability of a modeling methodology to provide added insight into system analysis and design. The modeling methodology used is bond graph modeling. An investigation into the creation of a bond graph model using the Lagrangian of the system is provided. Upon creation of the bond graph, system analysis is performed. To aid in the system analysis, an object-oriented approach to bond graph modeling is introduced. A framework is provided to simulate the bond graph directly. Through object-oriented simulation of a bond graph, the information contained within the bond graph can be exploited to create a measurement of system efficiency. A definition of system efficiency is given. This measurement of efficiency is used in the design of different controllers of varying architectures. Optimal control of a missile autopilot is discussed within the framework of the calculated system efficiency.
Bond strength of repaired amalgam restorations.
Rey, Rosalia; Mondragon, Eduardo; Shen, Chiayi
2015-01-01
This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam. Repaired specimens were stored in artificial saliva for 1, 10, 30, 120, or 360 days before being loaded to failure in a 3-point bending test. Statistical analysis showed significant changes in median FS over time in groups 2 and 4. The effect of the repair method on the FS values after each storage period was significant for most groups except the 30-day storage groups. Amalgam-amalgam repair with adequate condensation yielded the most consistent and durable bond. An amalgam bonding agent could be beneficial when firm condensation on the repair surface cannot be achieved or when tooth structure is involved. Composite resin can be a viable option for amalgam repair in an esthetically demanding region, but proper mechanical modification of the amalgam surface and selection of the proper bonding system are essential. PMID:26325656
Hydrogen bonding in substituted formic acid dimers.
Senthilkumar, L; Ghanty, Tapan K; Ghosh, Swapan K; Kolandaivel, P
2006-11-23
The hydrogen-bonded dimers of formic acid derivatives XCOOH (X = H, F, Cl, and CH3) have been investigated using density functional theory (B3LYP) and second-order Møller-Plesset perturbation (MP2) methods, with the geometry optimization carried out using 6-311++G(2d,2p) basis set. The dimerization energies calculated using aug-cc-pVXZ (with X = D and T) basis have been extrapolated to infinite basis set limit using the standard methodology. The results indicate that the fluorine-substituted formic acid dimer is the most stable one in comparison to the others. Topological analysis carried out using Bader's atoms in molecules (AIM) theory shows good correlation of the values of electron density and its Laplacian at the bond critical points (BCP) with the hydrogen bond length in the dimers. Natural bond orbital (NBO) analysis carried out to study the charge transfer from the proton acceptor to the antibonding orbital of the X-H bond in the complexes reveals that most of the dimers are associated with conventional H-bonding except a few, where improper blue-shifting hydrogen bonds are found to be present. PMID:17107113
Bingwu Wang; Guangxian Xu; Zhida Chen
2004-01-01
The electronic structure and chemical bonding in a recently synthesized inorganic fullerene-like molecule, [CuCl]20[Cp*FeP5]12[Cu-(CH3CN) +\\u000a 2Cl?]5 has been studied by a density functional approach. Geometrical optimization of the three basic structural units of the molecule\\u000a is performed with Amsterdam Density Functional Program. The results are in agreement with the experiment. Localized MO’s obtained\\u000a by Boys-Foster method give a clear picture
Representing geometrical knowledge.
Anderson, J A
1997-01-01
This paper introduces perspex algebra which is being developed as a common representation of geometrical knowledge. A perspex can currently be interpreted in one of four ways. First, the algebraic perspex is a generalization of matrices, it provides the most general representation for all of the interpretations of a perspex. The algebraic perspex can be used to describe arbitrary sets of coordinates. The remaining three interpretations of the perspex are all related to square matrices and operate in a Euclidean model of projective space-time, called perspex space. Perspex space differs from the usual Euclidean model of projective space in that it contains the point at nullity. It is argued that the point at nullity is necessary for a consistent account of perspective in top-down vision. Second, the geometric perspex is a simplex in perspex space. It can be used as a primitive building block for shapes, or as a way of recording landmarks on shapes. Third, the transformational perspex describes linear transformations in perspex space that provide the affine and perspective transformations in space-time. It can be used to match a prototype shape to an image, even in so called 'accidental' views where the depth of an object disappears from view, or an object stays in the same place across time. Fourth, the parametric perspex describes the geometric and transformational perspexes in terms of parameters that are related to everyday English descriptions. The parametric perspex can be used to obtain both continuous and categorical perception of objects. The paper ends with a discussion of issues related to using a perspex to describe logic. PMID:9304680
Aggregation dynamics of molecular bonds between compliant materials.
Jiang, Hongyuan; Qian, Jin; Lin, Yuan; Ni, Yong; He, Linghui
2015-04-14
In this paper, we develop a mechanochemical modeling framework in which the spatial-temporal evolution of receptor-ligand bonds takes place at the interface between two compliant media in the presence of an externally applied tensile load. Bond translocation, dissociation and association occur simultaneously, resulting in dynamic aggregation of molecular bonds that is regulated by mechanical factors such as material compliance and applied stress. The results show that bond aggregation is energetically favorable in the out-of-equilibrium process with convoluted time scales from bond diffusion and reaction. Material stiffness is predicted to contribute to adhesion growth and an optimal level of applied stress leads to the maximized size of bond clusters for integrin-based adhesion, consistent with related experimental observations on focal adhesions of cell-matrix interactions. The stress distribution within bond clusters is generally non-uniform and governed by the stress concentration index. PMID:25706682
Generalized Geometric Quantum Speed Limits
Diego Paiva Pires; Marco Cianciaruso; Lucas C. Céleri; Gerardo Adesso; Diogo O. Soares-Pinto
2015-07-21
The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the non uniqueness of a bona fide measure of distinguishability defined on the quantum state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits, and provides instances of novel bounds which are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, clarifying the role of classical populations versus quantum coherences in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.
Generalized Geometric Quantum Speed Limits
Diego Paiva Pires; Marco Cianciaruso; Lucas C. Céleri; Gerardo Adesso; Diogo O. Soares-Pinto
2015-09-30
The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the non uniqueness of a bona fide measure of distinguishability defined on the quantum state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits, and provides instances of novel bounds which are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, clarifying the role of classical populations versus quantum coherences in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.
Mesh Generation And Optimal Triangulation
Marshall Bern; David Eppstein
1992-01-01
We survey the computational geometry relevant to #nite element meshgeneration. We especially focus on optimal triangulations of geometric domainsin two- and three-dimensions. An optimal triangulation is a partitionof the domain into triangles or tetrahedra, that is best according to somecriterion that measures the size, shape, or number of triangles. We discussalgorithms both for the optimization of triangulations on a #xed
Aerospace plane guidance using geometric control theory
NASA Technical Reports Server (NTRS)
Van Buren, Mark A.; Mease, Kenneth D.
1990-01-01
A reduced-order method employing decomposition, based on time-scale separation, of the 4-D state space in a 2-D slow manifold and a family of 2-D fast manifolds is shown to provide an excellent approximation to the full-order minimum-fuel ascent trajectory. Near-optimal guidance is obtained by tracking the reduced-order trajectory. The tracking problem is solved as regulation problems on the family of fast manifolds, using the exact linearization methodology from nonlinear geometric control theory. The validity of the overall guidance approach is indicated by simulation.
Triangular spin tubes with bond randomness
NASA Astrophysics Data System (ADS)
Miura, Yoko; Manaka, Hirotaka
2013-06-01
We performed X-ray diffraction, magnetic susceptibility, and magnetization experiments on nonequilateral triangular spin tubes composed of ?-KCr1- x Fe x F4 ( x = 0˜0.13), which consisted of one-dimensional Heisenberg antiferromagnets coexisting with geometrically-frustrated spin systems with bond randomness. The variation of lattice parameters with x may indicate that the Fe3+ ions constitute the low-spin state ( S = 1/2). As a result of analyses of the frustration factor and the spin-flop transition field, we found that the effect of geometrical spin frustration was enhanced and that the magnetic anisotropy was weakened as x was increased. Because these results are remarkably similar to the previous results for ?-KCr1- x Al x F4, the effect of the chemical impurity substitutions, whether they are magnetic or nonmagnetic ions, on ?-KCrF4 is clearly understood.
Bonded semiconductor substrate
Atwater, Jr.; Harry A. (South Pasadena, CA), Zahler; James M. (Pasadena, CA)
2010-07-13
Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.
Geometric integration in Born-Oppenheimer molecular dynamics
NASA Astrophysics Data System (ADS)
Odell, Anders; Delin, Anna; Johansson, Börje; Cawkwell, Marc J.; Niklasson, Anders M. N.
2011-12-01
Geometric integration schemes for extended Lagrangian self-consistent Born-Oppenheimer molecular dynamics, including a weak dissipation to remove numerical noise, are developed and analyzed. The extended Lagrangian framework enables the geometric integration of both the nuclear and electronic degrees of freedom. This provides highly efficient simulations that are stable and energy conserving even under incomplete and approximate self-consistent field (SCF) convergence. We investigate three different geometric integration schemes: (1) regular time reversible Verlet, (2) second order optimal symplectic, and (3) third order optimal symplectic. We look at energy conservation, accuracy, and stability as a function of dissipation, integration time step, and SCF convergence. We find that the inclusion of dissipation in the symplectic integration methods gives an efficient damping of numerical noise or perturbations that otherwise may accumulate from finite arithmetics in a perfect reversible dynamics.
NASA Technical Reports Server (NTRS)
Plueddemann, E.
1986-01-01
Primers employed in bonding together the various material interfaces in a photovoltaic module are being developed. The approach develops interfacial adhesion by generating actual chemical bonds between the various materials bonded together. The current status of the program is described along with the progress toward developing two general purpose primers for ethylene vinyl acetate (EVA), one for glass and metals, and another for plastic films.
U. Gosele; Q.-Y. Tong
1998-01-01
When mirror-polished, flat, and clean wafers of almost any material are brought into contact at room temperature, they are locally attracted to each other by van der Waals forces and adhere or bond. This phenomenon is referred to as wafer bonding. The most prominent applications of wafer bonding are silicon-on-insulator (SOI) devices, silicon-based sensors and actuators, as well as optical
Hydrogen bonding and anaesthesia
NASA Astrophysics Data System (ADS)
Sándorfy, C.
2004-12-01
General anaesthetics act by perturbing intermolecular associations without breaking or forming covalent bonds. These associations might be due to a variety of van der Waals interactions or hydrogen bonding. Neurotransmitters all contain OH or NH groups, which are prone to form hydrogen bonds with those of the neurotransmitter receptors. These could be perturbed by anaesthetics. Aromatic rings in amino acids can act as weak hydrogen bond acceptors. On the other hand the acidic hydrogen in halothane type anaesthetics are weak proton donors. These two facts together lead to a probable mechanism of action for all general anaesthetics.
A First Extension of Geometric Control Theory to Underwater Vehicles
Smith, Ryan N.
Mathematics Department, e-mail: mchyba@math.hawaii.edu Ocean & Resources Engineering Department, e-mail: ryan a test-bed AUV. We compare these geometrically computed controls to time and energy optimal controls are able to validate our theoretical results based on the experiments conducted using the time and energy
Shape Reconstruction Incorporating Multiple Non-linear Geometric Constraints
Fisher, Bob
Academic Publishers. Printed in the Netherlands. revisedpaper.tex; 6/04/2000; 15:35; p.1 #12;2 3D scanning deals with the reconstruction of 3D geometric shapes based on observed noisy 3D measurements optimization Abbreviations: CAD Computer Aided-design; 3D Three-Dimensional; LS Least squares Table
Geometric design of motions constrained by a contacting surface pair
Pottmann, Helmut
Hauptstrasse 8-10/113, A-1040 Wien, Austria To the memory of Josef Hoschek Abstract We discuss the following problem which arises in robot motion planning, NC ma- chining and computer animation: Given are a fixed line geometry. Geometric methods are used for the numerical solution of the arising optimization
ON EDGE DETECTION, EDGE INTEGRATION AND GEOMETRIC ACTIVE CONTOURS
R. Kimmel; A. M. Bruckstein
We recently realized that the Marr-Hildreth edges, computed as the zero crossings of the image Laplacian, can be viewed as optimal edge integration curves solving a geometric variational problem. We used this observation to derive a new set of edge integration and object seg- mentation procedures. Here we show that the edge detectors proposed by Haralick, and subsequently claimed to
Bond energy effects on strength, cooperativity and robustness of molecular structures
Chou, Chia-Ching; Buehler, Markus J.
2011-01-01
A fundamental challenge in engineering biologically inspired materials and systems is the identification of molecular structures that define fundamental building blocks. Here, we report a systematic study of the effect of the energy of chemical bonds on the mechanical properties of molecular structures, specifically, their strength and robustness. By considering a simple model system of an assembly of bonds in a cluster, we demonstrate that weak bonding, as found for example in H-bonds, results in a highly cooperative behaviour where clusters of bonds operate synergistically to form relatively strong molecular clusters. The cooperative effect of bonding results in an enhanced robustness since the drop of strength owing to the loss of a bond in a larger cluster only results in a marginal reduction of the strength. Strong bonding, as found in covalent interactions such as disulphide bonds or in the backbone of proteins, results in a larger mechanical strength. However, the ability for bonds to interact cooperatively is lost, and, as a result, the overall robustness is lower since the mechanical strength hinges on individual bonds rather than a cluster of bonds. The systematic analysis presented here provides general insight into the interplay of bond energy, robustness and other geometric parameters such as bond spacing. We conclude our analysis with a correlation of structural data of natural protein structures, which confirms the conclusions derived from our study. PMID:23050078
The role of bond tangency and bond gap in hard sphere crystallization of chains.
Karayiannis, Nikos Ch; Foteinopoulou, Katerina; Laso, Manuel
2015-03-01
We report results from Monte Carlo simulations on dense packings of linear, freely-jointed chains of hard spheres of uniform size. In contrast to our past studies where bonded spheres along the chain backbone were tangent, in the present work a finite tolerance in the bond is allowed. Bond lengths are allowed to fluctuate in the interval [?, ? + dl], where ? is the sphere diameter. We find that bond tolerance affects the phase behaviour of hard-sphere chains, especially in the close vicinity of the melting transition. First, a critical dl(crit) exists marking the threshold for crystallization, whose value decreases with increasing volume fraction. Second, bond gaps enhance the onset of phase transition by accelerating crystal nucleation and growth. Finally, bond tolerance has an effect on crystal morphologies: in the tangent limit the majority of structures correspond to stack-faulted random hexagonal close packing (rhcp). However, as bond tolerance increases a wealth of diverse structures can be observed: from single fcc (or hcp) crystallites to random hcp/fcc stackings with multiple directions. By extending the simulations over trillions of MC steps (10(12)) we are able to observe crystal-crystal transitions and perfection even for entangled polymer chains in accordance to the Ostwald's rule of stages in crystal polymorphism. Through simple geometric arguments we explain how the presence of rigid or flexible constraints affects crystallization in general atomic and particulate systems. Based on the present results, it can be concluded that proper tuning of bond gaps and of the connectivity network can be a controlling factor for the phase behaviour of model, polymer-based colloidal and granular systems. PMID:25594158
Protein Folding: A New Geometric Analysis
Walter A. Simmons; Joel L. Weiner
2008-09-11
A geometric analysis of protein folding, which complements many of the models in the literature, is presented. We examine the process from unfolded strand to the point where the strand becomes self-interacting. A central question is how it is possible that so many initial configurations proceed to fold to a unique final configuration. We put energy and dynamical considerations temporarily aside and focus upon the geometry alone. We parameterize the structure of an idealized protein using the concept of a ribbon from differential geometry. The deformation of the ribbon is described by introducing a generic twisting Ansatz. The folding process in this picture entails a change in shape guided by the local amino acid geometry. The theory is reparamaterization invariant from the start, so the final shape is independent of folding time. We develop differential equations for the changing shape. For some parameter ranges, a sine-Gordon torsion soliton is found. This purely geometric waveform has properties similar to dynamical solitons. Namely: A threshold distortion of the molecule is required to initiate the soliton, after which, small additional distortions do not change the waveform. In this analysis, the soliton twists the molecule until bonds form. The analysis reveals a quantitative relationship between the geometry of the amino acids and the folded form.
NASA Astrophysics Data System (ADS)
Omohundro, Stephen M.
1990-06-01
Emergent computation in the form of geometric learning is central to the development of motor and perceptual systems in biological organisms and promises to have a similar impact on emerging technologies including robotics, vision, speech, and graphics. This paper examines some of the trade-offs involved in different implementation strategies, focusing on the tasks of learning discrete classifications and smooth nonlinear mappings. The trade-offs between local and global representations are discussed, a spectrum of distributed network implementations are examined, and an important source of computational inefficiency is identified. Efficient algorithms based on k-d trees and the Delaunay triangulation are presented and the relevance to biological networks is discussed. Finally, extensions of both the tasks and the implementations are given.
Goldberg, P.W.
1993-04-01
In this paper we consider the problem of learning the positions of spheres in metric spaces, given as data randomly drawn points classified according to whether they are internal or external to an unknown sphere. The particular metrics under consideration are geometrical shape metrics, and the results are intended to be applicable to the problem of learning to identify a shape from related shapes classified according to whether they resemble it visually. While it is typically NP-hard to locate a central point for a hypothesis sphere, we find that it is however often possible to obtain a non-spherical hypothesis which can accurately predict whether further random points lie within the unknown sphere. We exhibit algorithms which achieve this, and in the process indicate useful general techniques for computational learning. Finally we exhibit a natural shape metric and show that it defines a class of spheres not predictable in this sense, subject to standard cryptographic assumptions.
Geometric Frustration with Disorder
NASA Astrophysics Data System (ADS)
Woo, Nayoon; Silevitch, Daniel M.; Rosenbaum, Thomas F.
2014-03-01
We study the effects of Nd doping on the geometrically-frustrated Heisenberg antiferromagnet Gadolinium Gallium Garnet (GGG), using linear and nonlinear ac magnetic susceptibility. Doping levels from 0.1 to 1 percent Nd alleviate the intrinsic frustration of pure GGG and elevate the ordering temperature compared to the pure material. We use nonlinear pump-probe magnetic susceptometry to examine cluster dynamics for both the pure and the doped series. At low frequency (~10 Hz), spectral hole burning is possible, indicating the presence of spin clusters with discrete energy levels largely decoupled from the overall spin bath. At kHz, we find a Fano resonance, revealing scattering pathways between spin cluster excitations and the bath. We trace the evolution of this resonance behavior as a function of dopant concentration.
Geometrical aspects of entanglement
Leinaas, Jon Magne; Myrheim, Jan; Ovrum, Eirik
2006-07-15
We study geometrical aspects of entanglement, with the Hilbert-Schmidt norm defining the metric on the set of density matrices. We focus first on the simplest case of two two-level systems and show that a 'relativistic' formulation leads to a complete analysis of the question of separability. Our approach is based on Schmidt decomposition of density matrices for a composite system and nonunitary transformations to a standard form. The positivity of the density matrices is crucial for the method to work. A similar approach works to some extent in higher dimensions, but is a less powerful tool. We further present a numerical method for examining separability and illustrate the method by a numerical study of bound entanglement in a composite system of two three-level systems.
Making geometrical optics exact
Philbin, T G
2014-01-01
Geometrical optics (GO) is widely used in studies of electromagnetic materials because of its ease of use compared to full-wave numerical simulations. Exact solutions for waves can, however, differ significantly from the GO approximation. In particular, effects that are "perfect" for waves cannot usually be derived using GO. Here we give a method for designing materials in which GO is exact for some waves. This enables us to find interesting analytical solutions for exact wave propagation in inhomogeneous media. Two examples of the technique are given: a material in which two point sources do not interfere, and a perfect isotropic cloak for waves from a point source. We also give the form of material response required for GO to be exact for all waves.
Information geometric nonlinear filtering
NASA Astrophysics Data System (ADS)
Newton, Nigel J.
2015-06-01
This paper develops information geometric representations for nonlinear filters in continuous time. The posterior distribution associated with an abstract nonlinear filtering problem is shown to satisfy a stochastic differential equation on a Hilbert information manifold. This supports the Fisher metric as a pseudo-Riemannian metric. Flows of Shannon information are shown to be connected with the quadratic variation of the process of posterior distributions in this metric. Apart from providing a suitable setting in which to study such information-theoretic properties, the Hilbert manifold has an appropriate topology from the point of view of multi-objective filter approximations. A general class of finite-dimensional exponential filters is shown to fit within this framework, and an intrinsic evolution equation, involving Amari's -1-covariant derivative, is developed for such filters. Three example systems, one of infinite dimension, are developed in detail.
NASA Astrophysics Data System (ADS)
Li, Hui; Liu, Yufang; Yang, Yonggang; Yang, Dapeng; Sun, Jinfeng
2014-12-01
The excited-state properties of intramolecular hydrogen bonding in the compounds based on 2-(2-hydroxyphenyl)-1,3-benzoxazole (6 and its tautomers 6a and 6b) have been investigated using theoretical methods. According to the geometric optimization and IR spectra in the ground and excited states calculated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods respectively, the type of intramolecular hydrogen bonding N⋯Hsbnd O in 6 and 6a is demonstrated to be significantly strengthened, while Nsbnd H⋯O in the tautomers 6a and 6b are proved to be sharply weakened upon excitation to excited state S1. The calculated absorption peaks of 6 are in good accordance with the experimental results. Moreover, other compounds based on 6 that R1 and R2 are both substituted as well as that only R1 is substituted are investigated to understand the effect of substituent on intramolecular hydrogen bonding. It is found that the hydrogen bond strength can be controlled by the inductive field effect of the substituent. In addition, the intramolecular charge transfers (ICT) of the S1 state for 6 and its tautomers 6a and 6b were theoretically investigated by analyses of molecular orbital.
Sebastian, S; Sylvestre, S; Jayarajan, D; Amalanathan, M; Oudayakumar, K; Gnanapoongothai, T; Jayavarthanan, T
2013-01-15
In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the ?* and ?* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis. PMID:23123244
Activation of C-H and B-H bonds through agostic bonding: an ELF/QTAIM insight.
Zins, Emilie-Laure; Silvi, Bernard; Alikhani, M Esmaïl
2015-04-14
Agostic bonding is of paramount importance in C-H bond activation processes. The reactivity of the ? C-H bond thus activated will depend on the nature of the metallic center, the nature of the ligand involved in the interaction and co-ligands, as well as on geometric parameters. Because of their importance in organometallic chemistry, a qualitative classification of agostic bonding could be very much helpful. Herein we propose descriptors of the agostic character of bonding based on the electron localization function (ELF) and Quantum Theory of Atoms in Molecules (QTAIM) topological analysis. A set of 31 metallic complexes taken, or derived, from the literature was chosen to illustrate our methodology. First, some criteria should prove that an interaction between a metallic center and a ? X-H bond can indeed be described as "agostic" bonding. Then, the contribution of the metallic center in the protonated agostic basin, in the ELF topological description, may be used to evaluate the agostic character of bonding. A ? X-H bond is in agostic interaction with a metal center when the protonated X-H basin is a trisynaptic basin with a metal contribution strictly larger than the numerical uncertainty, i.e. 0.01 e. In addition, it was shown that the weakening of the electron density at the X-Hagostic bond critical point with respect to that of X-Hfree well correlates with the lengthening of the agostic X-H bond distance as well as with the shift of the vibrational frequency associated with the ?X-H stretching mode. Furthermore, the use of a normalized parameter that takes into account the total population of the protonated basin, allows the comparison of the agostic character of bonding involved in different complexes. PMID:25760795
Diffusion Bonding of Silicon Carbide for MEMS-LDI Applications
NASA Technical Reports Server (NTRS)
Halbig, Michael C.; Singh, Mrityunjay; Shpargel, Tarah P.; Kiser, J. Douglas
2007-01-01
A robust joining approach is critically needed for a Micro-Electro-Mechanical Systems-Lean Direct Injector (MEMS-LDI) application which requires leak free joints with high temperature mechanical capability. Diffusion bonding is well suited for the MEMS-LDI application. Diffusion bonds were fabricated using titanium interlayers between silicon carbide substrates during hot pressing. The interlayers consisted of either alloyed titanium foil or physically vapor deposited (PVD) titanium coatings. Microscopy shows that well adhered, crack free diffusion bonds are formed under optimal conditions. Under less than optimal conditions, microcracks are present in the bond layer due to the formation of intermetallic phases. Electron microprobe analysis was used to identify the reaction formed phases in the diffusion bond. Various compatibility issues among the phases in the interlayer and substrate are discussed. Also, the effects of temperature, pressure, time, silicon carbide substrate type, and type of titanium interlayer and thickness on the microstructure and composition of joints are discussed.
NASA Astrophysics Data System (ADS)
Wan, L. F.; Beckman, S. P.
2015-09-01
The underlying nature of atomic bonds in the orthorhombic AlLiB14 crystal is studied using first-principles methods. Significant charge transfer is observed upon bonding, which is responsible to maintain good mechanical strength of the crystal. Individual bonding or anti-bonding states are identified which explains the correlation between the optimal mechanical strength and the electronic occupation of individual atomic orbitals. When the Fermi level is 0.35 eV inside the valence band the crystal has its maximum strength, which is the nominal position of the Fermi level in the experimentally-observed, off-stoichometric orthorhombic borides. These results indicate that the soft-phonon modes previously identified in the literature allow the crystal to reach the optimal stability. Due to the unique crystallographic symmetry, the impact of uniaxial compressive strain on the individual bonds is also examined in the end.
The variational subspace valence bond method
NASA Astrophysics Data System (ADS)
Fletcher, Graham D.
2015-04-01
The variational subspace valence bond (VSVB) method based on overlapping orbitals is introduced. VSVB provides variational support against collapse for the optimization of overlapping linear combinations of atomic orbitals (OLCAOs) using modified orbital expansions, without recourse to orthogonalization. OLCAO have the advantage of being naturally localized, chemically intuitive (to individually model bonds and lone pairs, for example), and transferrable between different molecular systems. Such features are exploited to avoid key computational bottlenecks. Since the OLCAO can be doubly occupied, VSVB can access very large problems, and calculations on systems with several hundred atoms are presented.
Optical bonding reinforced by femtosecond laser welding
NASA Astrophysics Data System (ADS)
Lacroix, Fabrice; Hélie, David; Vallée, Réal
2011-09-01
Previous work on welding of optical materials with ultrashort laser pulses demonstrated that the ability to achieve good contact between components limits the applicability of the technology to only very small components. We have overcome this limitation and demonstrated the capability to weld similar and dissimilar materials using femtosecond laser pulses over several mm2 areas between intimately contacted surfaces. Our joining process is realised in two steps. Firstly, the two pieces which must be joined are direct bonded, thereby inducing optical contact throughout the whole potentially bondable surface. Subsequently, the direct bond is reinforced by the inscription of femtosecond laser weld seams in a sealing pattern in order to enclose the central region of the direct bond. We demonstrated the applicability of this process to identical glass, dissimilar glass and glass-semiconductor. We also measured a mean threefold increase in joint strength for such bonds between fused silica windows with only a few welding seams. The final assembly is free from macroscopic surface deformations. Furthermore, by optimizing the laser exposure parameters, we can avoid microscopic defects inside and around weld seams. Finally, the bonding method does not alter the optical transmission properties at the center of the sealed region. As opposed to the use of adhesives, such bonds resist to important thermal constraints and are free from chemical contaminants, degassing and ageing. Potential applications may be considered in the fields of aerospace, laser manufacturing, semiconductor industry, solar cell protection, precision manufacturing and many more.
Gordon, Nirit
2013-01-01
Dissociation leaves a psychic void and a lingering sense of psychic absence. How do 2 people bond while they are both suffering from dissociation? The author explores the notion of a dissociative bond that occurs in the aftermath of trauma--a bond that holds at its core an understanding and shared detachment from the self. Such a bond is confined to unspoken terms that are established in the relational unconscious. The author proposes understanding the dissociative bond as a transitional space that may not lead to full integration of dissociated knowledge yet offers some healing. This is exemplified by R. Prince's (2009) clinical case study. A relational perspective is adopted, focusing on the intersubjective aspects of a dyadic relationship. In the dissociative bond, recognition of the need to experience mutual dissociation can accommodate a psychic state that yearns for relationship when the psyche cannot fully confront past wounds. Such a bond speaks to the need to reestablish a sense of human relatedness and connection when both parties in the relationship suffer from disconnection. This bond is bound to a silence that becomes both a means of protection against the horror of traumatic memory and a way to convey unspoken gestures toward the other. PMID:23282044
ERIC Educational Resources Information Center
Bank, Stephen P.; Kahn, Michael D.
The relationships among brothers and sisters are infinitely varied, but whatever their characteristics, these bonds last throughout life. This book examines the sibling relationship as a distinctive emotional, passionate, painful, and solacing power. Chapter 1, "Unraveling the Sibling Bond," addresses research on siblings and development of the…
Abhay Shukla; E. D. Isaacs; D. R. Hamann; P. M. Platzman
2001-01-01
The hydrogen bond consisting of a hydrogen atom positioned asymmetrically between a nitrogen and an oxygen atom (N-H...O) plays a central role in the structure and functionality of proteins and amino acids. The urea crystal is a simple system in which such a hydrogen bond exists. We have measured Compton profile anisotropies in crystalline urea which reveal subtle modulations linked
Structures and bonding character of cyclic AsO 2 and AsS 2 systems in the doublet state
NASA Astrophysics Data System (ADS)
Sun, Lixiang; Bu, Yuxiang; Yan, Shihai
2004-03-01
The structural and bonding properties have been predicted for AsO 2 and AsS 2 species in doublet state using density functional theory (DFT) and the second-order Møller-Plesset (MP2) method with 6-311+G* basis set. The geometrical optimizations and the harmonic vibrational frequency analysis are performed using DFT methods. The relevant state-state energy separations are also determined using CCSD(T) and QCISD(T) methods. The results indicate that each species possesses a 2B 2 ground state. The AsO 2( 2A 2) should be classified as superoxide and the AsS 2( 2A 2) should be classified as supersulfide, but their ground states should be classified as dioxide and disulfide, respectively.
Seung-Ho Kim; Kiwon Lee; Kyung-Wook Paik
2010-01-01
In this study, the effects of vertical ultrasonic (VUS) bonding parameters such as vibration amplitudes and bonding pressures were investigated and optimized in terms of thermal deformation of TSP polymer substrates, electrical continuity, and pull adhesion strength of anisotropic conductive adhesive (ACA) joints. And the reliability of VUS bonded TSP ACA joints were evaluated at various test conditions. As the
Extent of Hydrogen-Bond Protection in Folded Proteins: A Constraint on Packing Architectures
Berry, R. Stephen
Extent of Hydrogen-Bond Protection in Folded Proteins: A Constraint on Packing Architectures Ariel structuring and ultimately exclusion of water by hydrophobes surrounding backbone hydrogen bonds turn hydrophobes yields an optimal hydrogen-bond stabilization. This motif is shown to be nearly ubiquitous
Are Negative Option Prices Possible? The Callable U.S. Treasury-Bond Puzzle
Francis A. Longstaff
1992-01-01
Market prices for callable Treasury bonds often imply negative values for the implicit call option. The author considers a variety of possible explanations for these negative values including the Treasury's track record in calling bonds optimally, tax-related effects, tax-timing options, and bond liquidity. None of these factors accounts for the negative values. Although the costs of short selling may explain
Computational Topology for Geometric Design
Peters, Thomas J.
"mi03 2005/ page i i i i i i i i Computational Topology for Geometric Design and Molecular Design Edward L. F. Moore , Thomas J. Peters Abstract The nascent field of computational topology holds great. Commercial CAGD packages depend upon complementary geometric and topological algorithms. The emergence of geo
Technology of bonding elastomers
NASA Astrophysics Data System (ADS)
Symes, Ted; Oldfield, David
The paper reviews current bonding theories and examines the application of these concepts to the production of reliable commercial bonding elastomers. Fundamental aspects of elastomer bonding (such as the elastomer surface thermodynamics, the mechanics of the adhesive failure, and the elastomer self-adhesion) are discussed along with the types of elastomers and the technology used in producing these compounds, with particular consideration given to the factors affecting the strength and durability of elastomer bonds. Tables are presented listing elastomers' designations according to ASTM D1418; the elastomers' surface properties; the elastomer surface energy dispersive and polar components; the commonly used elastomer types selected to meet specific ASTM test requirements; the ASTM adhesion test methods; and selected metal primers, cover coats, and bonding agents.
Ultrasonically bonded value assembly
NASA Technical Reports Server (NTRS)
Salvinski, R. J. (inventor)
1975-01-01
A valve apparatus capable of maintaining a fluid-tight seal over a relatively long period of time by releasably bonding a valve member to its seat is described. The valve member is bonded or welded to the seat and then released by the application of the same energy to the bond joint. The valve member is held in place during the bonding by a clamping device. An appropriate force device can activate the opening and closing of the valve member. Various combinations of material for the valve member and valve seat can be utilized to provide an adequate sealing bond. Aluminum oxide, stainless steel, inconel, tungsten carbide as hard materials and copper, aluminum, titanium, silver, and gold as soft materials are suggested.
Aakeröy, Christer B.; Spartz, Christine L.; Dembowski, Sean; Dwyre, Savannah; Desper, John
2015-01-01
As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system. As hydrogen and halogen bonds have several fundamental features in common, it is often difficult to predict which will be the primary interaction in a supramolecular system, especially as they have comparable strength and geometric requirements. To address this challenge, a series of molecules containing both hydrogen- and halogen-bond donors were co-crystallized with various monotopic, ditopic symmetric and ditopic asymmetric acceptor molecules. The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values. It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately. PMID:26306192
An introduction to shape optimization, with
Frey, Pascal
An introduction to shape optimization, with applications in fluid mechanics Charles Dapogny1 to the steady increase in the cost of raw materials, which has made it necessary to optimize mechanical parts for shape optimization (III) II. Geometric shape optimization Â· The topology (i.e. the number of holes in 2d
Mutual influence between conventional and unconventional lithium bonds.
Esrafili, Mehdi D; Fatehi, Parvin; Solimannejad, Mohammad
2014-04-01
The interplay between conventional and unconventional lithium bonds interactions in NCLi?NCLi?XCCX and CNLi?CNLi?XCCX (X=H, F, Cl, Br, OH, CH3, and OCH3) complexes is studied by ab initio calculations. Cooperative effects are observed when Li?N(C) and Li?? bonds coexist in the same complex. These effects are analyzed in terms of geometric, energetic and electron charge density properties of the complexes. The cooperative effects are larger in those complexes with shorter intermolecular distances than in those with the longest ones. The electron density at the lithium bond critical points can be regarded as a good descriptor of the degree of cooperative effects. An excellent linear correlation can be obtained between the cooperative energies and the calculated spin-spin coupling constants across the lithium bonds. PMID:24657745
Ultrasonic friction power during Al wire wedge-wedge bonding
NASA Astrophysics Data System (ADS)
Shah, A.; Gaul, H.; Schneider-Ramelow, M.; Reichl, H.; Mayer, M.; Zhou, Y.
2009-07-01
Al wire bonding, also called ultrasonic wedge-wedge bonding, is a microwelding process used extensively in the microelectronics industry for interconnections to integrated circuits. The bonding wire used is a 25?m diameter AlSi1 wire. A friction power model is used to derive the ultrasonic friction power during Al wire bonding. Auxiliary measurements include the current delivered to the ultrasonic transducer, the vibration amplitude of the bonding tool tip in free air, and the ultrasonic force acting on the bonding pad during the bond process. The ultrasonic force measurement is like a signature of the bond as it allows for a detailed insight into mechanisms during various phases of the process. It is measured using piezoresistive force microsensors integrated close to the Al bonding pad (Al-Al process) on a custom made test chip. A clear break-off in the force signal is observed, which is followed by a relatively constant force for a short duration. A large second harmonic content is observed, describing a nonsymmetric deviation of the signal wave form from the sinusoidal shape. This deviation might be due to the reduced geometrical symmetry of the wedge tool. For bonds made with typical process parameters, several characteristic values used in the friction power model are determined. The ultrasonic compliance of the bonding system is 2.66?m/N. A typical maximum value of the relative interfacial amplitude of ultrasonic friction is at least 222nm. The maximum interfacial friction power is at least 11.5mW, which is only about 4.8% of the total electrical power delivered to the ultrasonic generator.
Geometric algebra, qubits, geometric evolution, and all that
Soiguine, Alexander M
2015-01-01
The earlier approach is used for description of qubits and geometric phase parameters, the things critical in the area of topological quantum computing. The used tool, Geometric (Clifford) Algebra is the most convenient formalism for that case. Generalization of formal complex plane to an an arbitrary plane in three dimensions and of usual Hopf fibration to the map generated by an arbitrary unit value element of even sub-algebra of the three-dimensional Geometric Algebra are resulting in more profound description of qubits compared to quantum mechanical Hilbert space formalism.
Geometric algebra, qubits, geometric evolution, and all that
Alexander M. Soiguine
2015-02-07
The earlier approach is used for description of qubits and geometric phase parameters, the things critical in the area of topological quantum computing. The used tool, Geometric (Clifford) Algebra is the most convenient formalism for that case. Generalization of formal complex plane to an an arbitrary plane in three dimensions and of usual Hopf fibration to the map generated by an arbitrary unit value element of even sub-algebra of the three-dimensional Geometric Algebra are resulting in more profound description of qubits compared to quantum mechanical Hilbert space formalism.
29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.
Code of Federal Regulations, 2010 CFR
2010-07-01
...2010-07-01 2010-07-01 false Use of existing bonds, separate bonds and additional bonding. 2580.412-20 Section...SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules § 2580.412-20 Use of existing...
29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.
Code of Federal Regulations, 2011 CFR
2011-07-01
...2011-07-01 2011-07-01 false Use of existing bonds, separate bonds and additional bonding. 2580.412-20 Section...SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules § 2580.412-20 Use of existing...
Absorption and quantitative characteristics of C-H bond and O-H bond of NIR
NASA Astrophysics Data System (ADS)
Wu, Zhisheng; Ouyang, Guoqing; Shi, Xinyuan; Ma, Qun; Wan, Guang; Qiao, Yanjiang
2014-11-01
The previous study mainly focused on the interpretation of the relationship between absorption characteristics and quantitative contribution in each near-infrared (NIR) frequency range. Furthermore, the absorption characteristics of NIR mainly cover overtones and combinations of molecular vibrations such as CH, OH, SH, and NH bonds. And it has been know that NIR wavelengths of C-H bond and O-H bond are assigned to different radio frequencies. This paper was intended to investigate the absorption characteristics of bond C-H and O-H bonds in NIR spectral range. Water and acetone which correspond to O-H and C-H bonds have been selected as typical solvents, as well as solutes. Calibration models were established using partial least square regression (PLS) and multiple linear regression (MLR). The parameter of the model were optimized by different spectral pretreatment methods. The result showed that the model set by Savitzky-Golay smooth (SG) in the spectral region of 810-1100 nm could successfully make accurate predictions. Short wave-NIR region has been discovered as optimum characteristic absorption of C-H and O-H bonds.
Fluxless eutectic bonding of GaAs-on-Si by using Ag/Sn solder
NASA Astrophysics Data System (ADS)
Eo, Sung-Hwa; Kim, Dae-Seon; Jeong, Ho-Jung; Jang, Jae-Hyung
2013-11-01
Fluxless GaAs-on-Si wafer bonding using Ag/Sn solder was investigated to realize uniform and void-free heterogeneous material integration. The effects of the diffusion barrier, Ag/Sn thickness, and Ar plasma treatment were studied to achieve the optimal fluxless bonding process. Pt on a GaAs wafer and Mo on a Si wafer act as diffusion barriers by preventing the flow of Ag/Sn solder into both the wafers. The bonding strength is closely related to the Ag/Sn thickness and Ar plasma treatment. A shear strength test was carried out to investigate the bonding strength. Under identical bonding conditions, the Ag/Sn thickness was optimized to achieve higher bonding strength and to avoid the formation of voids due to thermal stress. An Ar plasma pretreatment process improved the bonding strength because the Ar plasma removed carbon contaminants and metal-oxide bonds from the metal surface.
Wafer-Level Thermocompression Bonds
Tsau, Christine H.
Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding without the application of an electric field or complicated pre-bond cleaning procedure. The presence of a ductile ...
Conifolds and geometric transitions
Gwyn, Rhiannon; Knauf, Anke [Department of Physics, McGill University, 3600 Rue Universite, Montreal, Quebec, H3A 2T8 (Canada)
2008-10-15
Conifold geometries have recieved much attention in string theory and string-inspired cosmology recently, in particular the Klebanov-Strassler background that is known as the ''warped throat.'' This paper provides a pedagogical explanation for the singularity resolution in this geometry and emphasizes its connection to geometric transitions. The first part focuses on the gauge theory dual to the Klebanov-Strassler background, including the T-dual intersecting branes description. Then, a connection to the Gopakumar-Vafa conjecture for open-closed string duality is presented and a series of papers verifying this model on the supergravity level is summarized. An appendix provides extensive background material about conifold geometries. Special attention is given to their complex structures and the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov-Tseytlin) and resolved (Pando Zayas-Tseytlin) conifolds are reevaluated. In agreement with earlier results, it is shown that only the singular solution allows a supersymmetric flux. However, the importance of using the correct complex structure to reach this conclusion is emphasized.
Geometric representation of two-qubit entanglement witnesses
NASA Astrophysics Data System (ADS)
Milne, Antony; Jennings, David; Rudolph, Terry
2015-07-01
Any two-qubit state can be represented geometrically by a steering ellipsoid inside the Bloch sphere. We extend this approach to represent any block-positive two-qubit operator B . We derive a classification scheme based on the positivity of detB and detBBT ; this shows that any ellipsoid inside the Bloch sphere must represent either a two-qubit state or a two-qubit entanglement witness. We focus on such witnesses and their corresponding ellipsoids, finding that properties such as witness optimality are naturally manifest in this geometric representation.
Critical appraisal. Resin bonding to zirconia.
Piascik, Jeffrey R
2012-12-01
Research has focused on adhesion and bond strengths to zirconia, but the question is "what is the gold standard--what is the bond strength we are trying to achieve?" Clinical data are needed to further understand adhesion issues--and studies are just now being published. Preliminary clinical research indicates that some failures are due to loss of adhesion but more are due to chipping of veneer porcelain. Commercial adhesion products are continuously being developed and optimized for clinical use. It is anticipated that the use of zirconia in dentistry will increase in the future, so reliable clinical adhesion solutions are needed. Based on the literature and the commercial products available to clinicians today, using novel primers (e.g., Z-PrimePlus) coupled with low pressure air-abrasion would be more than sufficient for adequate bonding of resin cement. PMID:23342396
On a Geometrical Study of Population Ecosystems
Mocioalca, Oana
On a Geometrical Study of Population Ecosystems ecosystems. In a two dimensional case, a locally geometrical study is given. Mathematics Subject In this paper, we shall survey some contribution to the geometrical study of mathematical models of ecosystems
Wire bonding process impact on low-k dielectric material in damascene copper integrated circuits
Vaidyanathan Kripesh; Mohandass Sivakumar; Loon Aik Lim; Rakesh Kumar; Mahadevan K. Iyer
2002-01-01
This study investigates wire bonding impact on low-k dielectric material used in dual damascene copper integrated circuits. The paper focuses on wire bond process optimization required for devices with soft low-k dielectric material compared to device with hard standard silicon dioxide dielectric. A fine pitch (60 ?m bond pitch) wire bonding process was established on test vehicles with SiO2 and
Antenna with Dielectric Having Geometric Patterns
NASA Technical Reports Server (NTRS)
Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)
2013-01-01
An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.
Ferroelectricity and isotope effects in hydrogen-bonded KDP crystals.
Koval, S; Kohanoff, J; Migoni, R L; Tosatti, E
2002-10-28
Based on an accurate first principles description of the energetics in H-bonded potassium-dihydrogen-phosphate crystals, we conduct a first study of nuclear quantum effects and of the changes brought about by deuteration. Tunneling is allowed only for clusters involving correlated protons and heavy ion displacements, the main effect of deuteration being a depletion of the proton probability density at the O-H-O bridge center, which in turn weakens its proton-mediated covalent bonding. The ensuing lattice expansion couples self-consistently with the proton off-centering, thus explaining both the giant isotope effect and its close connection with geometrical effects. PMID:12398635
A new decomposition strategy for parallel bonded molecular dynamics
Plimpton, S.; Hendrickson, B.; Heffelfinger, G.
1992-12-31
A method is described for parallelizing molecular dynamics (MD) simulations by block-decomposing the matrix of bonded and non-bonded force computations. It is particularly useful for organic simulations (polymers, proteins) because unlike spatial-decomposition methods, it requires no geometric information about the simulation domain. Because its communication cost scales as N/{radical}P. rather than N as in the all-to-all broadcast or ring-exchange techniques commonly used in this type of MD simulation, larger numbers of processors can be used effectively, yielding greater parallel speed-ups.
Geometric Effects on Electron Cloud
Wang, L
2007-07-06
The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit the machine performances by inducing beam instabilities, beam emittance increase, beam loss, vacuum pressure increases and increased heat load on the vacuum chamber wall. The electron multipacting is a kind of geometric resonance phenomenon and thus is sensitive to the geometric parameters such as the aperture of the beam pipe, beam shape and beam bunch fill pattern, etc. This paper discusses the geometric effects on the electron cloud build-up in a beam chamber and examples are given for different beams and accelerators.
Optical traps with geometric aberrations.
Roichman, Yael; Waldron, Alex; Gardel, Emily; Grier, David G
2006-05-20
We assess the influence of geometric aberrations on the in-plane performance of optical traps by studying the dynamics of trapped colloidal spheres in deliberately distorted holographic optical tweezers. The lateral stiffness of the traps turns out to be insensitive to moderate amounts of coma, astigmatism, and spherical aberration. Moreover holographic aberration correction enables us to compensate inherent shortcomings in the optical train, thereby adaptively improving its performance. We also demonstrate the effects of geometric aberrations on the intensity profiles of optical vortices, whose readily measured deformations suggest a method for rapidly estimating and correcting geometric aberrations in holographic trapping systems. PMID:16708086
Repeating Decimals and Geometric Series
NSDL National Science Digital Library
2011-01-01
This activity begins by reviewing conversions between fractions and decimals with an emphasis on repeating decimals. The formula for the partial sum of a geometric series is bypassed and students are directed to use find partial sums by using the “multiply, subtract, and solve” technique which mimics the derivation of the formula for the partial sum of a geometric series. This sets the stage for students to quickly find the fraction representation of a repeating decimal number. This activity would be well-suited as a prelude to introducing infinite and partial sums of geometric sequences.
The geometric resistivity correction factor for several geometrical samples
NASA Astrophysics Data System (ADS)
Yilmaz, Serdar
2015-08-01
This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conductivity measurement method using several geometrical samples. During the review of the literature, only the articles that include the effect of geometry on resistivity calculation were considered. Combinations of equations used for various geometries were also given. Mathematical equations were given in the text without details. Expressions for the most commonly used geometries were presented in a table for easy reference.
Gold Thermocompression Wafer Bonding
Spearing, S. Mark
Thermocompression bonding of gold is a promising technique for the fabrication and packaging microelectronic and MEMS devices. The use of a gold interlayer and moderate temperatures and pressures results in a hermetic, ...
Bonding aerogels with polyurethanes
Matthews, F.M.; Hoffman, D.M.
1989-11-01
Aerogels, porous silica glasses with ultra-fine cell size (30nm), are made by a solution gelation (sol-gel) process. The resulting gel is critical point dried to densities from 0.15--0.60 g/cc. This material is machinable, homogeneous, transparent, coatable and bondable. To bond aerogel an adhesive should have long cure time, no attack on the aerogel structure, and high strength. Several epoxies and urethanes were examined to determine if they satisfied these conditions. Bond strengths above 13 psi were found with double bubble and DP-110 epoxies and XI-208/ODA-1000 and Castall U-2630 urethanes. Hardman Kalex Tough Stuff'' A-85 hardness urethane gave 18 psi bond strength. Hardman A-85, Tuff-Stuff'' was selected for further evaluation because it produced bond strengths comparable to the adherend cohesive strength. 5 refs., 2 figs.
Not Available
1982-01-01
An intrinsically safe, electronic instrument has been developed that determines the holding quality of a fully grouted roof bolt by testing the integrity of the resin bond to both the bolt and to the surrounding rock.
NSDL National Science Digital Library
Northland Community and Technical College Biology Department
2007-12-12
This color animation of water molecules interacting and forming hydrogen bonds is a hybrid between a PowerPoint slide show an an animation. Students can replay portions or click next if they do not need to replay a segment.
Characterization of anodic bonding
Tudryn, Carissa Debra, 1978-
2004-01-01
Anodic bonding is a common process used in MicroElectroMechanical Systems (MEMS) device fabrication and packaging. Polycrystalline chemical vapor deposited (CVD) silicon carbide (SiC) is emerging as a new MEMS device and ...
Geometrical method of decoupling
NASA Astrophysics Data System (ADS)
Baumgarten, C.
2012-12-01
The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances) the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E?, B?, and P?, which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of) transformations must be symplectic and hence canonical. When used iteratively, the decoupling algorithm can also be applied to n-dimensional systems and requires O(n2) iterations to converge to a given precision.
subm. to PCCP Geometric and electronic structure of Pd/4-aminothiophenol/Au(111)
Pfeifer, Holger
subm. to PCCP Geometric and electronic structure of Pd/4-aminothiophenol/Au(111) metal. In a systematic approach, we first determined the adsorption of single 4-aminothiophenol (4-ATP) molecules on Au) via a single Pd-NH2 bond. However, the strong H-Pd interaction induces the dehydrogenation
NASA Astrophysics Data System (ADS)
Reznichenko, Alexander L.; Hultzsch, Kai C.
This account summarizes information on recently reported applications of organo-rare-earth metal complexes in various catalytic transformations of small molecules. The ?-bond metathesis at d0rare-earth metal centers plays a pivotal role in carbon-carbon and carbon-heteroatom bond forming processes. Relevant mechanistic details are discussed and the focus of the review lies in practical applications of organo-rare-earth metal complexes.
Water's Hydrogen Bond Strength
Martin Chaplin
2007-06-10
Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperatures. The overall conclusion of this investigation is that water's hydrogen bond strength is poised centrally within a narrow window of its suitability for life.
Adhesive Bonding and Performance Testing of Bonded Wood Products
Charles R. Frihart
2005-01-01
Despite the importance of durable wood bonds, the factors that lead to durability are not well understood, and the internal forces exerted upon the bondline are often overlooked. Durability requires that the bonded assembly resist dimensional changes of wood with fluctuation of wood moisture levels. Both bonding and bond breaking steps need to be understood at cellular and nanoscale, in
Geometric theory of meromorphic functions
2009-11-11
Geometric theory of meromorphic functions .... from below by a positive constant. ...... Levin and I.V. Ostrovskii, The dependence of the growth of an entire function on ... [48] Y. Sibuya, Global theory of a second order linear ordinary differential ...
Guitars, Violins, and Geometric Sequences
ERIC Educational Resources Information Center
Barger, Rita; Haehl, Martha
2007-01-01
This article describes middle school mathematics activities that relate measurement, ratios, and geometric sequences to finger positions or the placement of frets on stringed musical instruments. (Contains 2 figures and 2 tables.)
Geometric algorithms for reconfigurable structures
Benbernou, Nadia M
2011-01-01
In this thesis, we study three problems related to geometric algorithms of reconfigurable structures. In the first problem, strip folding, we present two universal hinge patterns for a strip of material that enable the ...
Geometric Analysis and General Relativity
Lars Andersson
2005-12-23
This article discusses methods of geometric analysis in general relativity, with special focus on the role of "critical surfaces" such as minimal surfaces, marginal surface, maximal surfaces and null surfaces.
Geometrical optics in general relativity
A. Loinger
2006-09-19
General relativity includes geometrical optics. This basic fact has relevant consequences that concern the physical meaning of the discontinuity surfaces propagated in the gravitational field - as it was first emphasized by Levi-Civita.
Uniform geometrical theory of diffraction
NASA Astrophysics Data System (ADS)
Pathak, P. H.
1987-06-01
Keller's geometrical theory of diffraction (GTD) represents a major breakthrough in solving a wide variety of electromagnetic (EM) radiation and scattering problems at high frequencies. In particular, the GTD is an extension of geometrical optics to include a class of diffracted rays via a generalization of Fermat's principle. These diffracted rays are initiated, for example, from geometrical and electrical discontinuities in a scatter, or from points of grazing incidence on smooth convex parts of the scattering surface. However, being a pure ray optical theory, the original GTD falls within the transition regions adjacent to geometric optical shadow boundaries where the diffracted field generally assumes its largest value. This limitation of the GTD is overcome via the uniform version of the GTD which requires the diffracted field to make the total high frequency field continuous across the optical shadow boundaries. The UTD solutions for the diffraction by edges and smooth convex surfaces are reviewed in detail after introducing the basic concepts of GTD.
Surface activation enhanced low temperature silicon wafer bonding
NASA Astrophysics Data System (ADS)
Gan, Qing
Direct wafer bonding technology has received great attention since 1985. It enables to realize the novel combinations of different materials for expanded functionality and provides a versatile device technology for transferring device layers to another wafer for further processing or device integration onto one wafer. Silicon direct wafer bonding has found a wide range of applications including Silicon-on-Insulator (SOI) wafers, micromechanical devices, and sensors and actuators. One of the challenges facing this technology is to achieve strong bonding at low temperatures that can survive post-wafer bonding processing. This dissertation presents the results of developing new wafer bonding processes for achieving high bonding energy at low temperatures. For thermal oxide covered silicon wafer bonding, dilute HF solution has been used to etch the wafers prior to room temperature bonding. The bonding energy has been significantly enhanced which reached silicon fracture energy after annealed at 100°C for 45 hours. For native oxide covered silicon wafers, the pre-treatment in dilute HNO3 and dilute HF mixtures has been found to be able to enhance the bonding energy at low temperatures. This is attributed to the incorporation of fluorine in native oxide during the pre-treatment. Various approaches have also been explored for hydrophobic silicon wafer bonding. Both boron doped surface layers and the amorphous surface layers have demonstrated an ability to significantly enhance the bonding energy at low temperatures, with silicon fracture energy achieved at 300--400°C for hydrophobically bonded pairs. The thermal management of heterojunction bipolar transistor (HBT) circuits fabricated by Symmetric Intrinsic HBT (SIHBT) processing was also studied in this research project using simulation method. Design criteria of selecting the surrogate substrates, interconnection dimension, and dielectric materials for the optimization of thermal management have been obtained.
Algorithms of NCG geometrical module
NASA Astrophysics Data System (ADS)
Gurevich, M. I.; Pryanichnikov, A. V.
2012-12-01
The methods and algorithms of the versatile NCG geometrical module used in the MCU code system are described. The NCG geometrical module is based on the Monte Carlo method and intended for solving equations of particle transport. The versatile combinatorial body method, the grid method, and methods of equalized cross sections and grain structures are used for description of the system geometry and calculation of trajectories.
Algorithms of NCG geometrical module
Gurevich, M. I.; Pryanichnikov, A. V.
2012-12-15
The methods and algorithms of the versatile NCG geometrical module used in the MCU code system are described. The NCG geometrical module is based on the Monte Carlo method and intended for solving equations of particle transport. The versatile combinatorial body method, the grid method, and methods of equalized cross sections and grain structures are used for description of the system geometry and calculation of trajectories.
Geometric calculations of thin shells
Wright, William Dennis
1967-01-01
GEOMETRIC CALCULATIONS OF THIN SHELLS A Thesis by WILLIAM DENNIS WRIGHT Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1967 Major Subject...: Computer Science GEOMETRIC CALCULATIONS OF THIN SHELLS A Thesis by WILLIAM DENNIS WRIGHT Approved as to style and content by: (Chairman of Committee) (Nember) August 1967 ACKNOWLEDGMENT I extend my sincerest appreciation to all of those who have...
Cosmology in geometric scalar gravity
NASA Astrophysics Data System (ADS)
Bittencourt, E.; Moschella, U.; Novello, M.; Toniato, J. D.
2014-12-01
We describe what cosmology looks like in the context of the geometric theory of gravity based on a single scalar field. There are two distinct classes of cosmological solutions. An interesting feature is the possibility of having a bounce without invoking exotic equations of state for the cosmic fluid. We also discuss cosmological perturbation and present the basis of structure formation by gravitational instability in the framework of the geometric scalar gravity.
Tanja Kortemme; Alexandre V. Morozov; David Baker
2003-01-01
Hydrogen bonding is a key contributor to the specificity of intramolecular and intermolecular interactions in biological systems. Here, we develop an orientation-dependent hydrogen bonding potential based on the geometric characteristics of hydrogen bonds in high-resolution protein crystal structures, and evaluate it using four tests related to the prediction and design of protein structures and protein–protein complexes. The new potential is
Geometric formulation of quantum mechanics
Hoshang Heydari
2015-03-01
Quantum mechanics is among the most important and successful mathematical model for describing our physical reality. The traditional formulation of quantum mechanics is linear and algebraic. In contrast classical mechanics is a geometrical and non-linear theory defined on a symplectic geometry. However, after invention of general relativity, we are convinced that geometry is physical and affect us in all scale. Hence the geometric formulation of quantum mechanics sought to give a unified picture of physical systems based on its underling geometrical structures, e.g., now, the states are represented by points of a symplectic manifold with a compatible Riemannian metric, the observable are real-valued functions on the manifold, and quantum evolution is governed by the symplectic flow that is generated by a Hamiltonian function. In this work we will give a compact introduction to main ideas of geometric formulation of quantum mechanics. We will provide the reader with the details of geometrical structures of both pure and mixed quantum states. We will also discuss and review some important applications of geometric quantum mechanics.
Fundamentals of fiber bonding in thermally point-bonded nonwovens
NASA Astrophysics Data System (ADS)
Chidambaram, Aparna
Thermal point bonding (TPB) uses heat and pressure to bond a web of fibers at discrete points imparting strength to the manufactured fabric. This process significantly reduces the strength and elongation of the bridging fibers between bond points while strengthening the web. Single fiber experiments were performed with four structurally different polypropylene fibers to analyze the inter-relationships between fiber structure, fiber properties and bonding process. Two fiber types had a low birefringence sheath or surface layer while the remaining had uniform birefringence profiles through their thickness. Bonds were formed between isolated pairs of fibers by subjecting the fibers to a calendering process and simulating TPB process conditions. The dependence of bond strength on bonding temperature and on the type of fiber used was evaluated. Fiber strengths before and after bonding were measured and compared to understand the effect of bonding on fiber strength. Additionally, bonded fiber strength was compared to the strength of single fibers which had experienced the same process conditions as the bonded pairs. This comparison estimated the effect of mechanical damage from pressing fibers together with steel rolls while creating bonds in TPB. Interfiber bond strength increased with bonding temperature for all fiber types. Fiber strength decreased with increasing bonding temperature for all fiber types except for one type of low birefringent sheath fibers. Fiber strength degradation was unavoidable at temperatures required for successful bonding. Mechanical damage from compression of fibers between rolls was an insignificant factor in this strength loss. Thermal damage during bonding was the sole significant contributor to fiber strength degradation. Fibers with low birefringence skins formed strong bonds with minimal fiber strength loss and were superior to fibers without such surface layers in TPB performance. A simple model to predict the behavior of a two-bond fabric strip was developed and it demonstrated the negative effect of inhomogeneous straining of fibers arising from the commonly used diamond bond shape and pervasive fiber-to-fiber elongation variability on fabric strength.
Chemical Bonding, again ionic bonding (in salts): transfer of e-
Zakarian, Armen
Chemical Bonding, again · ionic bonding (in salts): transfer of e- · covalent bonding (organic 3A 4A 5A 6A 7A 8A 2 3 (exceptions) #12;Ionic Bonding Model See sample problem 9.1 4Na + O2 ! 2Na2O 2s 2p 3s 3p 3s 3p inner shell inner shell #12;Ionic Bonding Model See sample problem 9.1 4Na + O2
Crystal structure prediction via particle-swarm optimization
NASA Astrophysics Data System (ADS)
Wang, Yanchao; Lv, Jian; Zhu, Li; Ma, Yanming
2010-09-01
We have developed a method for crystal structure prediction from “scratch” through particle-swarm optimization (PSO) algorithm within the evolutionary scheme. PSO technique is different with the genetic algorithm and has apparently avoided the use of evolution operators (e.g., crossover and mutation). The approach is based on an efficient global minimization of free-energy surfaces merging total-energy calculations via PSO technique and requires only chemical compositions for a given compound to predict stable or metastable structures at given external conditions (e.g., pressure). A particularly devised geometrical structure parameter which allows the elimination of similar structures during structure evolution was implemented to enhance the structure search efficiency. The application of designed variable unit-cell size technique has greatly reduced the computational cost. Moreover, the symmetry constraint imposed in the structure generation enables the realization of diverse structures, leads to significantly reduced search space and optimization variables, and thus fastens the global structure convergence. The PSO algorithm has been successfully applied to the prediction of many known systems (e.g., elemental, binary, and ternary compounds) with various chemical-bonding environments (e.g., metallic, ionic, and covalent bonding). The high success rate demonstrates the reliability of this methodology and illustrates the promise of PSO as a major technique on crystal structure determination.
hp calculators HP 50g Bond Price
Vetter, Frederick J.
hp calculators HP 50g Bond Price The FINANCE menu Bond Price Practice solving for the price of a bond #12;hp calculators HP 50g Bond Price hp calculators - 2 - HP 50g Bond Price The FINANCE menu;hp calculators HP 50g Bond Price hp calculators - 3 - HP 50g Bond Price Solution: Since the bond
Surface analysis in composite bonding
NASA Technical Reports Server (NTRS)
Messick, D. L.; Wightman, J. P.
1982-01-01
The role of the interfacial region in determining the bond strength and durability of composite bonds is discussed. The characterization of a variety of carbon fibers including Celion 6000 using both scanning electron microscopy and X-ray photoelectron spectroscopy is discussed. The emphasis is on composite bonding, that is, the adhesive bonding between composites in contrast to fiber-matrix interaction. The primary objective of the research is the characterization of composite surfaces before adhesive bonding and after fracture of bonded specimens. Work done on the analysis of composite samples pretreated in a number of ways prior to bonding is detailed.
Geometrical interpretation and curvature distribution in nanocarbons
NASA Astrophysics Data System (ADS)
Gupta, Sanju; Saxena, Avadh
2011-04-01
Despite extensive research on microscopic structure and physical property characterization of advanced nanocarbon systems, they have not been viewed as topologically distinct nanoscale materials with various geometries (curvature). This work is motivated by our recent work [S. Gupta and A. Saxena, J. Raman Spectrosc. 40, 1127 (2009)] where we introduced the notion of "global" topology for novel nanocarbons and provided systematic trends by monitoring the phonon spectra via resonance Raman spectroscopy, which led to the paradigm of curvature/topology ? property ? functionality relationship in these materials. Here we determined the distribution of the mean (H) and Gaussian (K) curvatures as pertinent observables for geometric characterization taking into account the observed geometrical parameters, that is, radius, polar, azimuthal, or conical angle associated with tubular (single, double-, and multi-walled nanotubes; K = 0), spherical (hypo- and hyperfullerenes; K > 0) and complex (helical nanoribbons and nanotori/nanorings; K < 0) nanocarbon geometries to quantify the interplay of intrinsic surface curvature and topology, wherein global topology of the overall sp2-bonded carbon (sp2C) constrains local topology of the constituent carbon rings. We also studied various other structures such as catenoid and saddle-shaped surfaces as interesting nanocarbons. We compared these results with highly oriented pyrolytic graphite and monolayer graphene as layered and planar systems, respectively. Moreover, nanocarbons discussed herein are their derivatives. Curvature leads to nonlinearity that manifests itself in some form of symmetry breaking which can be extrapolated to topological variation due to nanoscale defects. Thus it may either close/open the bandgap leading to the introduction of new Raman spectroscopy signatures and optical absorption peaks, changes in mechanical properties, electrical behavior, and electronic density of states and possibly inducing magnetism. Finally, we elucidate the role of curved geometry in Casimir forces arising in carbon nanostructures.
Asymmetric bifurcated halogen bonds.
Novák, Martin; Foroutan-Nejad, Cina; Marek, Radek
2015-03-01
Halogen bonding (XB) is being extensively explored for its potential use in advanced materials and drug design. Despite significant progress in describing this interaction by theoretical and experimental methods, the chemical nature remains somewhat elusive, and it seems to vary with the selected system. In this work we present a detailed DFT analysis of three-center asymmetric halogen bond (XB) formed between dihalogen molecules and variously 4-substituted 1,2-dimethoxybenzene. The energy decomposition, orbital, and electron density analyses suggest that the contribution of electrostatic stabilization is comparable with that of non-electrostatic factors. Both terms increase parallel with increasing negative charge of the electron donor molecule in our model systems. Depending on the orientation of the dihalogen molecules, this bifurcated interaction may be classified as '?-hole - lone pair' or '?-hole - ?' halogen bonds. Arrangement of the XB investigated here deviates significantly from a recent IUPAC definition of XB and, in analogy to the hydrogen bonding, the term bifurcated halogen bond (BXB) seems to be appropriate for this type of interaction. PMID:25656525
NASA Technical Reports Server (NTRS)
Christian, Jerry D.
1973-01-01
Students are not generally made aware of the extraordinary magnitude of the strengths of chemical bonds in terms of the forces required to pull them apart. Molecular bonds are usually considered in terms of the energies required to break them, and we are not astonished at the values encountered. For example, the Cl2 bond energy, 57.00 kcal/mole, amounts to only 9.46 x 10(sup -20) cal/molecule, a very small amount of energy, indeed, and impossible to measure directly. However, the forces involved in realizing the energy when breaking the bond operate over a very small distance, only 2.94 A, and, thus, f(sub ave) approx. equals De/(r - r(sub e)) must be very large. The forces involved in dissociating the molecule are discussed in the following. In consideration of average forces, the molecule shall be assumed arbitrarily to be dissociated when the atoms are far enough separated so that the potential, relative to that of the infinitely separated atoms, is reduced by 99.5% from the potential of the molecule at the equilibrium bond length (r(sub e)) for Cl2 of 1.988 A this occurs at 4.928 A.
Gustavo R. Gonzalez-Martin
2000-09-19
A previously proposed geometric definition of mass in terms of energy, in a geometrical unified theory, is used to obtain a numerical expression for a ratio of masses of geometrical excitations. The resultant geometric ratio is approximately equal the ratio of the proton to electron physical masses.
A Geometric Approach to Quantum State Separation
Emilio Bagan; Vadim Yerokhin; Andi Shehu; Edgar Feldman; Janos A. Bergou
2015-06-27
Probabilistic quantum state transformations can be characterized by the degree of state separation they provide. This, in turn, sets limits on the success rate of these transformations. We consider optimum state separation of two known pure states in the general case where the known states have arbitrary a priori probabilities. The problem is formulated from a geometric perspective and shown to be equivalent to the problem of finding tangent curves within two families of conics that represent the unitarity constraints and the objective functions to be optimized, respectively. We present the corresponding analytical solutions in various forms. In the limit of perfect state separation, which is equivalent to unambiguous state discrimination, the solution exhibits a phenomenon analogous to a second order symmetry breaking phase transition. We also propose a linear optics implementation of separation which is based on the dual rail representation of qubits and single-photon multiport interferometry.
Random broadcast on random geometric graphs
Bradonjic, Milan; Elsasser, Robert; Friedrich, Tobias
2009-01-01
In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.
Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach.
Arrieta, Jorge; Cartwright, Julyan H E; Gouillart, Emmanuelle; Piro, Nicolas; Piro, Oreste; Tuval, Idan
2015-01-01
Mixing fluid in a container at low Reynolds number- in an inertialess environment-is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the "belly phase," peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing. PMID:26154384
Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach
Arrieta, Jorge; Cartwright, Julyan H. E.; Gouillart, Emmanuelle; Piro, Nicolas; Piro, Oreste; Tuval, Idan
2015-01-01
Mixing fluid in a container at low Reynolds number— in an inertialess environment—is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the “belly phase,” peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing. PMID:26154384
Federal Register 2010, 2011, 2012, 2013, 2014
2012-05-31
...Enhanced Bonding Requirements Upon CBP's Acceptance of Qualified Superseding Bond Application...requirements (EBR bond) upon the agency's acceptance of a qualified superseding bond application...Permit Cancellation of EBR Bond Upon Acceptance of Qualified Superseding Bond CBP...
Hydrogen bond and halogen bond inside the carbon nanotube
NASA Astrophysics Data System (ADS)
Wang, Weizhou; Wang, Donglai; Zhang, Yu; Ji, Baoming; Tian, Anmin
2011-02-01
The hydrogen bond and halogen bond inside the open-ended single-walled carbon nanotubes have been investigated theoretically employing the newly developed density functional M06 with the suitable basis set and the natural bond orbital analysis. Comparing with the hydrogen or halogen bond in the gas phase, we find that the strength of the hydrogen or halogen bond inside the carbon nanotube will become weaker if there is a larger intramolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom donor to the antibonding orbital of the X-H or X-Hal bond involved in the formation of the hydrogen or halogen bond and will become stronger if there is a larger intermolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom acceptor to the antibonding orbital of the X-H or X-Hal bond. According to the analysis of the molecular electrostatic potential of the carbon nanotube, the driving force for the electron-density transfer is found to be the negative electric field formed in the carbon nanotube inner phase. Our results also show that the X-H bond involved in the formation of the hydrogen bond and the X-Hal bond involved in the formation of the halogen bond are all elongated when encapsulating the hydrogen bond and halogen bond within the carbon nanotube, so the carbon nanotube confinement may change the blue-shifting hydrogen bond and the blue-shifting halogen bond into the red-shifting hydrogen bond and the red-shifting halogen bond. The possibility to replace the all electron nanotube-confined calculation by the simple polarizable continuum model is also evaluated.
Hydrogen bond and halogen bond inside the carbon nanotube.
Wang, Weizhou; Wang, Donglai; Zhang, Yu; Ji, Baoming; Tian, Anmin
2011-02-01
The hydrogen bond and halogen bond inside the open-ended single-walled carbon nanotubes have been investigated theoretically employing the newly developed density functional M06 with the suitable basis set and the natural bond orbital analysis. Comparing with the hydrogen or halogen bond in the gas phase, we find that the strength of the hydrogen or halogen bond inside the carbon nanotube will become weaker if there is a larger intramolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom donor to the antibonding orbital of the X-H or X-Hal bond involved in the formation of the hydrogen or halogen bond and will become stronger if there is a larger intermolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom acceptor to the antibonding orbital of the X-H or X-Hal bond. According to the analysis of the molecular electrostatic potential of the carbon nanotube, the driving force for the electron-density transfer is found to be the negative electric field formed in the carbon nanotube inner phase. Our results also show that the X-H bond involved in the formation of the hydrogen bond and the X-Hal bond involved in the formation of the halogen bond are all elongated when encapsulating the hydrogen bond and halogen bond within the carbon nanotube, so the carbon nanotube confinement may change the blue-shifting hydrogen bond and the blue-shifting halogen bond into the red-shifting hydrogen bond and the red-shifting halogen bond. The possibility to replace the all electron nanotube-confined calculation by the simple polarizable continuum model is also evaluated. PMID:21303130
Cohen, Ronald C.
Effects of Alkali Metal Halide Salts on the Hydrogen Bond Network of Liquid Water Christopher D molecular orbitals on water by anions, and does not require significant distortion of the hydrogen bond of the hydrogen bond network. Introduction The evolution of molecular geometric and electronic structure during
Pandey, Ravi
First Principles Study of Polyatomic Clusters of AlN, GaN, and InN. 2. Chemical Bonding Aurora Form: February 17, 2000 In this paper we study the chemical bonding of the small (monomer, triatomic of the chemical bonding in these systems emerges from the geometrical ar- rangements found. The most stable
NASA Technical Reports Server (NTRS)
Ferrante, J.; Smith, J. R.; Rose, J. H.
1984-01-01
Although metallic adhesion has played a central part in much tribological speculation, few quantitative theoretical calculations are available. This is in part because of the difficulties involved in such calculations and in part because the theoretical physics community is not particularly involved with tribology. The calculations currently involved in metallic adhesion are summarized and shown that these can be generalized into a scaled universal relationship. Relationships exist to other types of covalent bonding, such as cohesive, chemisorptive, and molecular bonding. A simple relationship between surface energy and cohesive energy is offered.
Generalized Geometric Measure of Entanglement for Multiparty Mixed States
Tamoghna Das; Sudipto Singha Roy; Shrobona Bagchi; Avijit Misra; Aditi Sen De; Ujjwal Sen
2015-09-07
Computing entanglement of an arbitrary bipartite or multipartite mixed state is in general not an easy task as it usually involves complex optimization. Here we show that exploiting symmetries of certain mixed states, we can compute a genuine multiparty entanglement measure, the generalized geometric measure for these classes of mixed states. The chosen states have different ranks and consist of an arbitrary number of parties.
Anisotropy of bond projections in simple crystal structures
NASA Astrophysics Data System (ADS)
Šim?nek, Antonín
2011-10-01
The nearest-neighbor bond distances represented by the stick-and-ball model of a crystal are projected into planes in order to find the directions from where the projections have maximum or minimum values. The projection directions and their corresponding values of the maxima and minima are presented for simple cubic, body-centered-cubic, face-centered-cubic, sodium chloride, zinc sulfide, diamond, fluorite, cesium chloride, hexagonal close-packed, tungsten carbide, wurtzite, graphite, graphene, and aluminum boride structures. The purely geometrical considerations quantitatively reflect an anisotropy of the bond projections and provide data for a large amount of materials crystallizing in these structures. The presented results can be applied to the description, analysis, and understanding of anisotropic effects related to bond projection in 14 crystal structures. The application of hardness anisotropy for BN, SiC, and TiC is shown.
Geometrical modelling of textile reinforcements
NASA Technical Reports Server (NTRS)
Pastore, Christopher M.; Birger, Alexander B.; Clyburn, Eugene
1995-01-01
The mechanical properties of textile composites are dictated by the arrangement of yarns contained with the material. Thus to develop a comprehensive understanding of the performance of these materials, it is necessary to develop a geometrical model of the fabric structure. This task is quite complex, as the fabric is made form highly flexible yarn systems which experience a certain degree of compressability. Furthermore there are tremendous forces acting on the fabric during densification typically resulting in yarn displacement and misorientation. The objective of this work is to develop a methodology for characterizing the geometry of yarns within a fabric structure including experimental techniques for evaluating these models. Furthermore, some applications of these geometric results to mechanical prediction models are demonstrated. Although more costly than its predecessors, the present analysis is based on the detailed architecture developed by one of the authors and his colleagues and accounts for many of the geometric complexities that other analyses ignore.
Geometric scalar theory of gravity
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D. [Instituto de Cosmologia Relatividade Astrofisica ICRA - CBPF Rua Dr. Xavier Sigaud 150 - 22290-180 Rio de Janeiro - Brazil (Brazil); Moschella, U., E-mail: novello@cbpf.br, E-mail: eduhsb@cbpf.br, E-mail: Ugo.Moschella@uninsubria.it, E-mail: egoulart@cbpf.br, E-mail: jsalim@cbpf.br, E-mail: toniato@cbpf.br [Università degli Studi dell'Insubria - Dipartamento di Fisica e Matematica Via Valleggio 11 - 22100 Como - Italy (Italy)
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Double-bond defect modelling in As-S glasses
NASA Astrophysics Data System (ADS)
Boyko, V.; Shpotyuk, O.; Hyla, M.
2010-11-01
Ab initio calculations with the RHF/6-311G* basis set are used for geometrical optimization of regular pyramidal and defect quasi-tetrahedral clusters in binary As-S glasses. It is shown that quasi-tetrahedral S=AsS3/2 structural units are impossible as main network-building blocks in these glasses.
Maternal bonding in childhood moderates autonomic responses to distress stimuli in adult males.
Dalsant, Arianna; Truzzi, Anna; Setoh, Peipei; Esposito, Gianluca
2015-10-01
Mother-child bonding influences the development of cognitive and social skills. In this study we investigate how maternal attachment, developed in early childhood, modulates physiological responses to social stimuli later in life. Our results suggest that the autonomic nervous system's responses to vocal distress are moderated by the quality of participants' maternal bonding. In particular, participants with optimal maternal bonding showed a greater calming response to distressful stimuli whereas participants with non-optimal maternal bonding showed a heightened distress response. PMID:26162754
Geometrical and FEA study on Millipede Forming
NASA Astrophysics Data System (ADS)
Kong, Lingran; Tang, Di; Ding, Shichao; Zhang, Yuankun
2013-12-01
Millipede Forming is an innovative sheet metal forming approach that has been proposed and developed in Australia. U-channels, Z-channels or tubular products can be made by Millipede Forming. While a strip moves through an optimal transitional surface between the entry to exit of a forming stand, the redundant longitudinal membrane strain can be significantly reduced compared to the conventional roll forming, which is the essential principle to obtaining high quality products. The incremental forming process studied has demonstrated major advantages on space efficiency, power consumption and materials sensitivities. The purpose of this study is to investigate the effects of main geometrical parameters and their optimization, in order to minimize the redundant longitudinal strains into elastic to avoid the redundant plastic deformations at flange during forming. In this study, a mild-steel U-channel sample with 10 mm flange width, fabricated by Millipede Forming in a forming length of 200 mm has been studied. Theoretical longitudinal membrane strains at profile's edge of different transitional surfaces and downhill pass are also analyzed. The results showed that obtaining an optimal transitional surface is essential and necessary in controlling the peak longitudinal strain to an acceptable amount and that by increasing downhill pass, longitudinal strain can be significantly reduced. The optimized transitional surface and downhill pass flow were simulated by Abaqus, and the peak longitudinal strain was finally less than 0.2% through a very short forming length of 200 mm. The results prove that Millipede Forming can achieve a better product quality in a much shorter forming distance than conventional roll forming.
Geometrical Optics of Dense Aerosols
Hay, Michael J.; Valeo, Ernest J.; Fisch, Nathaniel J.
2013-04-24
Assembling a free-standing, sharp-edged slab of homogeneous material that is much denser than gas, but much more rare ed than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed fi eld, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the nite particle density reduces the eff ective Stokes number of the flow, a critical result for controlled focusing. __________________________________________________
Geometric integration for particle accelerators
NASA Astrophysics Data System (ADS)
Forest, Étienne
2006-05-01
This paper is a very personal view of the field of geometric integration in accelerator physics—a field where often work of the highest quality is buried in lost technical notes or even not published; one has only to think of Simon van der Meer Nobel prize work on stochastic cooling—unpublished in any refereed journal. So I reconstructed the relevant history of geometrical integration in accelerator physics as much as I could by talking to collaborators and using my own understanding of the field. The reader should not be too surprised if this account is somewhere between history, science and perhaps even fiction.
Geometrical Modeling of Steel Ropes
NASA Astrophysics Data System (ADS)
Stanová, Eva
2013-11-01
The paper deals with the mathematical geometric modeling of the ropes of circular cross- section. Such rope can be formed from strands of different shapes. There is considered steel rope made up of six strands, whose crosssection has oval, triangular or circular profil in this paper. The wires of these types of the strands are presented by parametric equations of the wire axis. The equations are implemented in the Pro/Engineer Wildfire V5 software for creating the geometrical model of the strand.
Geometrical spin symmetry and spin
Pestov, I. B.
2011-07-15
Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.
Geometric pumping in autophoretic channels.
Michelin, Sébastien; Montenegro-Johnson, Thomas D; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric
2015-07-15
Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory. PMID:26000567
Does Geometric Coupling Generates Resonances?
Jardim, I C; Landim, R R; Filho, R N Costa
2015-01-01
Geometrical coupling in a co-dimensional one Randall-Sundrum scenario (RS) is used to study resonances of $p-$form fields. The resonances are calculated using the transfer matrix method. The model studied consider the standard RS with delta-like branes, and branes generated by kinks and domain-wall as well. The parameters are changed to control the thickness of the smooth brane. With this a very interesting pattern is found for the resonances. The geometrical coupling does not generate resonances for the reduced $p-$form in all cases considered.
Does Geometric Coupling Generates Resonances?
I. C. Jardim; G. Alencar; R. R. Landim; R. N. Costa Filho
2015-05-08
Geometrical coupling in a co-dimensional one Randall-Sundrum scenario (RS) is used to study resonances of $p-$form fields. The resonances are calculated using the transfer matrix method. The model studied consider the standard RS with delta-like branes, and branes generated by kinks and domain-wall as well. The parameters are changed to control the thickness of the smooth brane. With this a very interesting pattern is found for the resonances. The geometrical coupling does not generate resonances for the reduced $p-$form in all cases considered.
Geometric pumping in autophoretic channels
Michelin, Sebastien; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric
2015-01-01
Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.
Geometric pumping in autophoretic channels
Sebastien Michelin; Thomas D. Montenegro Johnson; Gabriele De Canio; Nicolas Lobato-Dauzier; Eric Lauga
2015-05-07
Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.
Bonding silicones with epoxies
Tira
1980-01-01
It is shown that silicones, both room temperature vulcanizing (RTV) and millable rubber (press cured) can be successfully bonded to other materials using plasma treatment and epoxy adhesives. The plasma treatment using dry air atmosphere increases the surface energy of the silicone and thus provides a lower water contact angle. This phenomenon allows the epoxy adhesive to wet the silicone
ERIC Educational Resources Information Center
Holden, Alan
The field of inquiry into how atoms are bonded together to form molecules and solids crosses the borderlines between physics and chemistry encompassing methods characteristic of both sciences. At one extreme, the inquiry is pursued with care and rigor into the simplest cases; at the other extreme, suggestions derived from the more careful inquiry…
1978-01-01
The applications of diffusion bonding at the General Electric Neutron Devices Department are briefly discussed, with particular emphasis on the gold\\/gold or gold\\/indium joints made between metallized alumina ceramic parts in the vacuum switch tube and the crystal resonator programs. Fixtures which use the differential expansion of dissimilar metals are described and compared to one that uses hydraulic pressure to
Flax Fiber - Interfacial Bonding
Technology Transfer Automated Retrieval System (TEKTRAN)
Measured flax fiber physical and chemical properties potentially impact bonding and thus stress transfer between the matrix and fiber within composites. These first attempts at correlating flax fiber quality and biofiber composites contain the initial steps towards identifying key flax fiber charac...
Mukhopadhyay, Anamika; Pandey, Prasenjit; Chakraborty, Tapas
2010-04-15
In 1:1 CH...O hydrogen bonded complexes between haloforms and ethers, a correlation of the spectral shifts of nu(C-H) bands (Deltanu(C-H)) of the donors (haloforms) with C-O-C angular strain of the acceptors (ethers) is investigated by the electronic structure theory method at the MP2/6-311++G** level. The calculation predicts that the three-member cyclic ether (oxirane) that has the smallest C-O-C angle induces a much larger blue shifting effect on nu(C-H) transition of fluoroform compared with that by the open chain analogue, dimethyl ether. The natural bond orbital (NBO) analysis reveals that the effect originates because of higher "s" character in the hybrid lone electron pair orbital of the oxygen atom of the former, which is responsible for a smaller contribution to n(O) --> sigma*(C-H) hyperconjugation interaction energy between the donor-acceptor molecules. The optimized structures of the two complexes are largely different with respect to the intermolecular orientational parameters at the hydrogen bonding sites, and similar behavior is also predicted for the two chloroform complexes. Partial optimizations on a series of structures show that the total binding energy of the complexes are insensitive with respect to those geometric parameters. However, the Deltanu(C-H), hyperconjugation interaction energies and hybridization of the carbon-centric bonding orbital of the C-H bond are sensitive with respect to those parameters. The predicted Deltanu(C-H) of each complex is analyzed with respect to the IR spectral shift measured by van der Veken and coworkers in cryosolutions of inert gases. The disagreement found between the measured and calculated IR shifts is interpreted to be the outcome of deformation of the complex geometries along shallow binding potential energy surfaces owing to solvation in the liquefied inert gases. PMID:20334425
Buehler, Markus J.
Cooperative deformation of hydrogen bonds in beta-strands and beta-sheet nanocrystals Zhao Qin; published 14 December 2010 Beta-sheet protein domains are stabilized by weak hydrogen bonds, yet materials the number of hydrogen bonds that deform cooperatively. Through this analysis, we predict the optimal beta
Zhang, Zongbo; Wang, Xiaodong; Luo, Yi; He, Shengqiang; Wang, Liding
2010-06-15
A thermal assisted ultrasonic bonding method for poly(methyl methacrylate) (PMMA) microfluidic devices has been presented. The substrates were preheated to 20-30 degrees C lower than glass transition temperature (T(g)) of the polymer. Then low amplitude ultrasonic vibration was employed to generate facial heat at the interface of PMMA substrates. PMMA microfluidic chips were successfully bonded with bulk temperature well below T(g) of the material and with pressure two orders lower than conventional thermal bonding, which was of great benefit to reduce the deformation of microstructures. The bonding process was optimized by Taguchi method. This bonding technique showed numerous superiorities including high bonding strength (0.95MPa), low dimension loss (0.3-0.8%) and short bonding time. Finally, a micromixer was successfully bonded by this method and its performance was demonstrated. PMID:20441903
30 CFR 281.33 - Bonds and bonding requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
...DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER CONTINENTAL SHELF Financial Considerations § 281.33 Bonds and bonding requirements. (a) When the leasing notice specifies that payment...
Optimal domain decomposition strategies
NASA Technical Reports Server (NTRS)
Yoon, Yonghyun; Soni, Bharat K.
1995-01-01
The primary interest of the authors is in the area of grid generation, in particular, optimal domain decomposition about realistic configurations. A grid generation procedure with optimal blocking strategies has been developed to generate multi-block grids for a circular-to-rectangular transition duct. The focus of this study is the domain decomposition which optimizes solution algorithm/block compatibility based on geometrical complexities as well as the physical characteristics of flow field. The progress realized in this study is summarized in this paper.
hp calculators HP 50g Bond Yield
Vetter, Frederick J.
hp calculators HP 50g Bond Yield The FINANCE menu Bond Yield Practice solving for the yield of a bond #12;hp calculators HP 50g Bond Yield hp calculators - 2 - HP 50g Bond Yield The FINANCE menu interest semiannually. What is the yield if this bond is purchased? #12;hp calculators HP 50g Bond Yield hp
Raghavendra, B; Arunan, E
2007-10-01
Ab initio, DFT, and AIM theoretical studies on H-, Cl-, and Li-bonded complexes have been carried out with typical lone pair (H2O), pi (C2H4) and sigma (H2) bonded pairs, and unpaired (CH3) electrons as acceptors and HF, ClF, and LiF as donors. Optimization and frequency calculations have been carried out at reasonably high levels (MP2, DFT(B3LYP), and QCISD) with large basis sets up to aug-cc-pVTZ. Not surprisingly, all HF complexes show red shift in stretching frequency and the shift is correlated to the binding energy. However, the FCl...CH3 complex shows a large blue shift (about 200 cm-1), which appears to be the largest blue shift predicted for any weakly bound complex yet. Analysis of the normal modes of the complex indicates that the shift is due to the mixing of modes between donor and acceptor and it is qualitatively different from the blue shifts reported thus far in hydrogen-bonded complexes. For Cl- and Li-bonded complexes, a correlation between frequency shift and binding energy is not found. However, AIM theoretical analysis shows the similarity in all these interactions. The electron density at the bond critical point shows a strong correlation with the binding energy for H-, Cl-, and Li-bonded complexes. This appears to be the first report on a one-electron chlorine bond. PMID:17760431
Platonic Symmetry and Geometric Thinking
ERIC Educational Resources Information Center
Zsombor-Murray, Paul
2007-01-01
Cubic symmetry is used to build the other four Platonic solids and some formalism from classical geometry is introduced. Initially, the approach is via geometric construction, e.g., the "golden ratio" is necessary to construct an icosahedron with pentagonal faces. Then conventional elementary vector algebra is used to extract quantitative…
Celestial mechanics with geometric algebra
NASA Technical Reports Server (NTRS)
Hestenes, D.
1983-01-01
Geometric algebra is introduced as a general tool for Celestial Mechanics. A general method for handling finite rotations and rotational kinematics is presented. The constants of Kepler motion are derived and manipulated in a new way. A new spinor formulation of perturbation theory is developed.
Experimentally accessible geometrical separability criteria
NASA Astrophysics Data System (ADS)
Badziag, Piotr; Brukner, ?aslav; Laskowski, Wies?aw; Paterek, Tomasz; ?ukowski, Marek
2009-07-01
We present an intuitive geometrical approach to entanglement detection. It allows one to formulate simple and experimentally feasible sufficient conditions for entanglement. Within the approach we derive the necessary and sufficient condition for separability and discuss its relation with entanglement witnesses and positive maps.
Geometric quantum noise of spin.
Shnirman, Alexander; Gefen, Yuval; Saha, Arijit; Burmistrov, Igor S; Kiselev, Mikhail N; Altland, Alexander
2015-05-01
The presence of geometric phases is known to affect the dynamics of the systems involved. Here, we consider a quantum degree of freedom, moving in a dissipative environment, whose dynamics is described by a Langevin equation with quantum noise. We show that geometric phases enter the stochastic noise terms. Specifically, we consider small ferromagnetic particles (nanomagnets) or quantum dots close to Stoner instability, and investigate the dynamics of the total magnetization in the presence of tunneling coupling to the metallic leads. We generalize the Ambegaokar-Eckern-Schön effective action and the corresponding semiclassical equations of motion from the U(1) case of the charge degree of freedom to the SU(2) case of the magnetization. The Langevin forces (torques) in these equations are strongly influenced by the geometric phase. As a first but nontrivial application, we predict low temperature quantum diffusion of the magnetization on the Bloch sphere, which is governed by the geometric phase. We propose a protocol for experimental observation of this phenomenon. PMID:25978252
Geometric Transformations on a Microcomputer.
ERIC Educational Resources Information Center
Shilgalis, Thomas W.
1982-01-01
A program designed in BASIC for the Apple II computer that uses high resolution graphics to display geometric transformations is described. The four distance-preserving transformations included are translations, rotations, reflections, and glide-reflections. Shape-preserving dilations are also covered. (MP)
Geometrical Methods in Gauge Theory
Henrique de A. Gomes
2006-10-25
In this work we explore the geometrical interpretation of gauge theories through the formalism of fiber bundles. Moreover, we conduct an investigation in the topology of fiber bundles, providing a proof of the Classification Theorem. In the last chapter we present some applications, such as electromagnetism and generalized Kaluza-Klein Theory.
Polymer representations and geometric quantization
Miguel Campiglia
2011-11-02
Polymer representations of the Weyl algebra of linear systems provide the simplest analogues of the representation used in loop quantum gravity. The construction of these representations is algebraic, based on the Gelfand-Naimark-Segal construction. Is it possible to understand these representations from a Geometric Quantization point of view? We address this question for the case of a two dimensional phase space.
Geometric scaling in exclusive processes
NASA Astrophysics Data System (ADS)
Munier, S.; Wallon, S.
2003-10-01
We show that according to the present understanding of the energy evolution of the observables measured in deep-inelastic scattering, the photon-proton scattering amplitude has to exhibit geometric scaling at each impact parameter. We suggest a way to test this experimentally at HERA. A qualitative analysis based on published data is presented and discussed.
Algorithmic + Geometric characterization of CAR
Gill, Richard D.
but independent) CCAR 3 door problem X=door with car behind Y=two doors still closed = {your first choice, other door left closed} 3 door problem X=door with car behind Y=(your first choice, other door left closedAlgorithmic + Geometric characterization of CAR (Coarsening at Random) Richard Gill - Utrecht
Geometric Mechanics 2009 H. Waalkens
Hanssmann, Heinz
by 11th May The spherical pendulum consists of a particle of mass m moving on the twodimensional sphereGeometric Mechanics 2009 H. Waalkens Exercise Sheet 3 Spherical Pendulum and Monodromy. Return down the Lagrange function for the spherical pendulum. 2. Show that, after a suitable scaling
Geometric Mechanics 2009 H. Waalkens
Hanssmann, Heinz
by 11 th May The spherical pendulum consists of a particle of mass m moving on the twodimensional sphereGeometric Mechanics 2009 H. Waalkens Exercise Sheet 3 Spherical Pendulum and Monodromy. Return#] × [0, #], to write down the Lagrange function for the spherical pendulum. 2. Show that, after
Geometric theory of meromorphic functions
If X is given by some geometric construction, the problem arises to relate prop-. erties of ? to those of X. ... image under p. Then X becomes a metric space with an intrinsic metric, which ... Similarly, if p : X ? C, and the Euclidean. metric in C is ...
Experimental study of the geometric group-delay dispersion in graded-index media
NASA Astrophysics Data System (ADS)
Lin, Hoang Yan; Wang, Jyhpyng
1996-05-01
We use the highly sensitive method of spatially coherent white-light interferometry to measure the geometric group-delay dispersion in graded-index media. Our measurements confirm previous analyses that the geometric dispersion produced by off-axis beam propagation is anomalous (negative), hence may be used to eliminate the ubiquitous positive dispersion in optical systems. Fabrication of large index-gradient waveguides optimal for dispersion compensation is discussed.
Quantal trajectories and geometric phase
NASA Astrophysics Data System (ADS)
Carlsen, Olav Henrik
This thesis concerns the following topics: geometric phase in the context of Galilean invariance and quantum measurements, Rydberg states of hydrogen atoms, vibronic coupling in the E/otimes/epsilon Jahn-Teller system and realism in quantum computations. In the analyses the de Broglie-Bohm pilot-wave formulation of quantum mechanics is mainly used. It is shown that geometric phase is not Galilean invariant. Experimental implications are discussed and it is found that the experiments performed to date are frame independent. An experiment which is in principle able to detect the noninvariance is sketched. By adopting the measurement theory of the pilot-wave formulation it is shown how the measurement induced geometric phase continuously emerges. The Samuel-Bhandari geometric phase is identified as the nonrandom part of the total geometric phase induced in the measurement. Ensembles of particles for a circular Rydberg wave packet are studied. The trajectories of pilot-wave particles are shown to accurately imitate the behaviour of the wave packet in the high quantum number limit. The nonclassical features of the wave packet are intuitively explained by the nonvanishing quantum potential. Vibronic coupling in the Longuet-Higgins model of the E/otimes/epsilon Jahn-Teller system is investigated by means of quantal trajectories. The pilot-wave picture provides an intuitive tool for discussing time-scales. An argument based on ergodicity leads to an understanding of the averaging procedure over the electronic motion which provides the approximate nuclear motion. The existence of efficient quantum algorithms triggers questions on Natures ability of storing and processing information during quantum computations. The role of elements of reality in quantum computations is addressed using quantal trajectories. It is found that there is a many-to-one relationship between quantal trajectories and performed computations when quantum parallelism is utilized.
On the bond distance in methane
NASA Technical Reports Server (NTRS)
Bowen-Jenkins, Philippa; Pettersson, Lars G. M.; Siegbahn, Per; Almloef, Jan; Taylor, Peter R.
1987-01-01
The equilibrium bond distance in methane was optimized using coupled-pair functional and contracted CI wave functions, and a Gaussian basis that includes g-type functions on carbon and d-type functions on hydrogen. The resulting bond distance, when corrected for core-valence correlation effects, agrees with the experimental value of 2.052 a(0) to within the experimental uncertainty of 0.002 a(0). The main source of error in the best previous studies, which showed discrepancies with experiment of 0.007 a(0) is shown to be basis set incompleteness. In particular, it is important that the basis set be close to saturation, at least for the lower angular quantum numbers.
On the bond distance in methane
NASA Technical Reports Server (NTRS)
Bowen-Jenkins, Philippa; Pettersson, Lars G. M.; Siegbahn, Per; Almlof, Jan; Taylor, Peter R.
1988-01-01
The equilibrium bond distance in methane has been optimized using coupled-pair functional and contracted CI wave functions, and a Gaussian basis that includes g-type functions on carbon and d-type functions on hydrogen. The resulting bond distance, when corrected for core-valance correlation effects, agrees with the experimental value of 2.052 a(0) to within the experimental uncertainty of 0.002 a(0). The main source of error in the best previous studies, which showed discrepancies with experiment of 0.007 a(0) is shown to be basis set incompleteness. In particular, it is important that the basis set be close to saturation, at least for the lower angular quantum numbers.
Femtosecond quantum control of molecular bond formation
Nuernberger, Patrick; Wolpert, Daniel; Weiss, Horst; Gerber, Gustav
2010-01-01
Ultrafast lasers are versatile tools used in many scientific areas, from welding to eye surgery. They are also used to coherently manipulate light–matter interactions such as chemical reactions, but so far control experiments have concentrated on cleavage or rearrangement of existing molecular bonds. Here we demonstrate the synthesis of several molecular species starting from small reactant molecules in laser-induced catalytic surface reactions, and even the increase of the relative reaction efficiency by feedback-optimized laser pulses. We show that the control mechanism is nontrivial and sensitive to the relative proportion of the reactants. The control experiments open up a pathway towards photocatalysis and are relevant for research in physics, chemistry, and biology where light-induced bond formation is important. PMID:20505117
Water lubricates hydrogen-bonded molecular machines
NASA Astrophysics Data System (ADS)
Panman, Matthijs R.; Bakker, Bert H.; den Uyl, David; Kay, Euan R.; Leigh, David A.; Buma, Wybren Jan; Brouwer, Albert M.; Geenevasen, Jan A. J.; Woutersen, Sander
2013-11-01
The mechanical behaviour of molecular machines differs greatly from that of their macroscopic counterparts. This applies particularly when considering concepts such as friction and lubrication, which are key to optimizing the operation of macroscopic machinery. Here, using time-resolved vibrational spectroscopy and NMR-lineshape analysis, we show that for molecular machinery consisting of hydrogen-bonded components the relative motion of the components is accelerated strongly by adding small amounts of water. The translation of a macrocycle along a thread and the rotation of a molecular wheel around an axle both accelerate significantly on the addition of water, whereas other protic liquids have much weaker or opposite effects. We tentatively assign the superior accelerating effect of water to its ability to form a three-dimensional hydrogen-bond network between the moving parts of the molecular machine. These results may indicate a more general phenomenon that helps explain the function of water as the ‘lubricant of life’.
Water lubricates hydrogen-bonded molecular machines.
Panman, Matthijs R; Bakker, Bert H; den Uyl, David; Kay, Euan R; Leigh, David A; Buma, Wybren Jan; Brouwer, Albert M; Geenevasen, Jan A J; Woutersen, Sander
2013-11-01
The mechanical behaviour of molecular machines differs greatly from that of their macroscopic counterparts. This applies particularly when considering concepts such as friction and lubrication, which are key to optimizing the operation of macroscopic machinery. Here, using time-resolved vibrational spectroscopy and NMR-lineshape analysis, we show that for molecular machinery consisting of hydrogen-bonded components the relative motion of the components is accelerated strongly by adding small amounts of water. The translation of a macrocycle along a thread and the rotation of a molecular wheel around an axle both accelerate significantly on the addition of water, whereas other protic liquids have much weaker or opposite effects. We tentatively assign the superior accelerating effect of water to its ability to form a three-dimensional hydrogen-bond network between the moving parts of the molecular machine. These results may indicate a more general phenomenon that helps explain the function of water as the 'lubricant of life'. PMID:24153370
Bond Markets with Stochastic Volatility
Solna, Knut
- nection to defaultable bonds. Contents 1 Introduction 2 2 Pricing Bonds 3 2.1 The Term Structure Equation . . . . . . . . . . . . . . . . . . 4 2.2 Probabilistic Representation of the Bond Price . . . . . . . . . 5 3 Affine Models 6 3, Santa Bar- bara, CA 93106-3110, fouque@pstat.ucsb.edu, Work supported by NSF grant DMS-0455982
Obtaining low bond interest rates.
Bittel, S D; Grill, R R
1995-11-01
Healthcare executives whose organizations seek major capital financing through bond offerings typically focus their attention on obtaining the lowest possible bond placement fees for the services of underwriters, legal counsel, accounting firms, and other advisors. However, far greater savings can be achieved by employing a strategic approach to securing low bond interest rates. PMID:10151868
Rapid Adhesive Bonding of Composites
NASA Technical Reports Server (NTRS)
Stein, B. A.; Tyeryar, J. R.; Fox, R. L.; Sterling, S. Elmo, Jr.; Buckley, J. D.; Inge, Spencer V., Jr.; Burcher, L. G.; Wright, Robert E., Jr.
1986-01-01
Strong bonds created in less time and with less power than use of conventional bonding methods. Rapid adhesive bonding (RAB) technique for composites uses high-frequency induction heating toroids to quickly heat metallic susceptor impregnated with thermoplastic adhesive or sandwiched between thermoset or thermoplastic adhesive cloths or films. Susceptor steel screen or perforated steel foil.
Continuing Conversation about Continuing Bonds
ERIC Educational Resources Information Center
Klass, Dennis
2006-01-01
The article is a response to the contributions the special issue of Death Studies on continuing bonds. The contributions indicate that the conversation among scholars has clarified our thinking on how bonds function in individual grief. The author discussed two issues to help keep the conversation moving: (a) the relationship of continuing bonds…
Code of Federal Regulations, 2014 CFR
2014-10-01
...AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds...payment bonds required by Article 14 of the NSA-LUMPSUMREP Contract. The stand- ard...payment bond requirements of Article 14 of the NSA-LUMPSUMREP Contract, the...
Code of Federal Regulations, 2013 CFR
2013-10-01
...AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds...payment bonds required by Article 14 of the NSA-LUMPSUMREP Contract. The stand- ard...payment bond requirements of Article 14 of the NSA-LUMPSUMREP Contract, the...
Code of Federal Regulations, 2012 CFR
2012-10-01
...AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds...payment bonds required by Article 14 of the NSA-LUMPSUMREP Contract. The stand- ard...payment bond requirements of Article 14 of the NSA-LUMPSUMREP Contract, the...
Coulombic Models in Chemical Bonding.
ERIC Educational Resources Information Center
Sacks, Lawrence J.
1986-01-01
Compares the coulumbic point charge model for hydrogen chloride with the valence bond model. It is not possible to assign either a nonpolar or ionic canonical form of the valence bond model, while the covalent-ionic bond distribution does conform to the point charge model. (JM)
NASA Technical Reports Server (NTRS)
Altshuller, Aubrey P
1955-01-01
The average bond energies D(gm)(B-Z) for boron-containing molecules have been calculated by the Pauling geometric-mean equation. These calculated bond energies are compared with the average bond energies D(exp)(B-Z) obtained from experimental data. The higher values of D(exp)(B-Z) in comparison with D(gm)(B-Z) when Z is an element in the fifth, sixth, or seventh periodic group may be attributed to resonance stabilization or double-bond character.
Low temperature reactive bonding
Makowiecki, Daniel M. (Livermore, CA); Bionta, Richard M. (Livermore, CA)
1995-01-01
The joining technique requires no external heat source and generates very little heat during joining. It involves the reaction of thin multilayered films deposited on faying surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process.
NASA Astrophysics Data System (ADS)
Cawley, Peter
An account is given of the types of defect that can occur in adhesive joints, and the techniques currently employed for bond inspection in industrial settings are described. Attention is given to the levels of detection currently obtainable for poor cohesion/adhesion, and the detection of voids and porosity by conventional ultrasonics, sonic vibration, thermography, X-radiography, and holography. Research imperatives for the inspection of adhesive/adherend interfaces and cohesive properties are noted.
Disulfide bonds of acetylcholinesterase
MacPhee-Quigley, K.; Vedvick, T.; Taylor, P.; Taylor, S.
1986-05-01
The positions of the inter- and intrasubunit disulfide bridges were established for the 11S form of acetylcholinesterase (AChE) isolated from Torpedo californica. A major form of AChE localized within the basal lamina of the synapse is a dimensionally asymmetric molecule which contains either two (13S) or three (17S) sets of catalytic subunits linked to collagenous and non-collagenous structural subunits. Limited proteolysis yields a tetramer of catalytic subunits which sediments at 11S. Each catalytic subunit contains 8 cysteine residues. Initially, these Cys residues were identified following trypsin digestion of the reduced protein alkylated with (/sup 14/C)-iodoacetate. Peptides were resolved by gel filtration followed by reverse phase HPLC. To determine the disulfide bonding profile, native non-reduced 11S AChE was treated with a fluorescent, sulfhydryl-specific reagent, monobromobimane, prior to proteolytic digestion. One fluorescent Cys peptide was identified indicating that a single sulfhydryl residue was present in its reduced form. Three pairs of disulfide bonded peptides were identified, sequenced, and localized in the polypeptide chain. The Cys residue that is located in the C-terminal tryptic peptide was disulfide bonded to an identical peptide and thus forms the intersubunit crosslink. Finally, the cysteine positions have been compared with the sequence of the homologous protein, thyroglobulin. Both likely share a common pattern of folding.
Geometric and Material Nonlinear Structural Analysis
NASA Technical Reports Server (NTRS)
Whitcomb, J. D.; Dattaguru, B.
1986-01-01
GAMNAS (Geometric and Material Nonlinear Analysis of Structures) is twodimensional finite-element stress-analysis program supporting fracturemechanics studies of debonding and delamination. GAMNAS options include linear, geometricnonlinear, material-nonlinear, and combined geometric- and material-nonlinear analysis.
Geometric uncertainty relation for quantum ensembles
Hoshang Heydari; Ole Andersson
2014-12-12
Geometrical structures of quantum mechanics provide us with new insightful results about the nature of quantum theory. In this work we consider mixed quantum states represented by finite rank density operators. We review our geometrical framework that provide the space of density operators with Riemannian and symplectic structures, and we derive a geometric uncertainty relation for observables acting on mixed quantum states. We also give an example that visualizes the geometric uncertainty relation for spin-$\\frac{1}{2}$ particles.
Rieutord, F; Bataillou, B; Moriceau, H
2005-06-17
A description of the bonding front propagation between two adhesive plates is proposed. The model relates the velocity of a bonding front to the adhesion energy, with application to wafer direct bonding. Its derivation is based on a competition between the bonding energy and the viscous drag of the air flow in the gap between the two wafers. The model describes well the experimental data, including the wafer deformation profile during bonding or the dependence of the velocity on the gas viscosity, pressure, and wafer thickness. PMID:16090484
Effect of quantum nuclear motion on hydrogen bonding
NASA Astrophysics Data System (ADS)
McKenzie, Ross H.; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G.
2014-05-01
This work considers how the properties of hydrogen bonded complexes, X-H⋯Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H⋯O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4 - 3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends.
Effect of quantum nuclear motion on hydrogen bonding.
McKenzie, Ross H; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G
2014-05-01
This work considers how the properties of hydrogen bonded complexes, X-H?Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H?O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4-3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends. PMID:24811647
27 CFR 19.162 - Operations bond for distilled spirits plant and adjacent bonded wine cellar.
Code of Federal Regulations, 2013 CFR
2013-04-01
... Operations bond for distilled spirits plant and adjacent bonded wine cellar. 19...TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Requirements... Operations bond for distilled spirits plant and adjacent bonded wine cellar....
27 CFR 19.162 - Operations bond for distilled spirits plant and adjacent bonded wine cellar.
Code of Federal Regulations, 2014 CFR
2014-04-01
... Operations bond for distilled spirits plant and adjacent bonded wine cellar. 19...TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Requirements... Operations bond for distilled spirits plant and adjacent bonded wine cellar....
27 CFR 19.162 - Operations bond for distilled spirits plant and adjacent bonded wine cellar.
Code of Federal Regulations, 2012 CFR
2012-04-01
... Operations bond for distilled spirits plant and adjacent bonded wine cellar. 19...TREASURY LIQUORS DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Requirements... Operations bond for distilled spirits plant and adjacent bonded wine cellar....
27 CFR 19.162 - Operations bond for distilled spirits plant and adjacent bonded wine cellar.
Code of Federal Regulations, 2011 CFR
2011-04-01
... Operations bond for distilled spirits plant and adjacent bonded wine cellar. 19...TREASURY LIQUORS DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Requirements... Operations bond for distilled spirits plant and adjacent bonded wine cellar....
Geometric Algebra and Physics Anthony Lasenby
Hart, Gus
Geometric Algebra and Physics Anthony Lasenby Astrophysics Group, Cavendish Laboratory, Cambridge Microwave Background, and early universe Why am I here talking about `Geometric Algebra'? Came across effectively extends them to the relativistic domain And via `conformal geometric algebra' gives a whole new
CRYSTAL-LIKE GEOMETRIC MODELING ERIC LANDRENEAU
Keyser, John
CRYSTAL-LIKE GEOMETRIC MODELING A Thesis by ERIC LANDRENEAU Submitted to the Office of Graduate OF SCIENCE May 2005 Major Subject: Computer Science #12;CRYSTAL-LIKE GEOMETRIC MODELING A Thesis by ERIC Science #12;iii ABSTRACT Crystal-Like Geometric Modeling. (May 2005) Eric Landreneau, B.S., Texas A
Development of a Geometric Spatial Visualization Tool
ERIC Educational Resources Information Center
Ganesh, Bibi; Wilhelm, Jennifer; Sherrod, Sonya
2009-01-01
This paper documents the development of the Geometric Spatial Assessment. We detail the development of this instrument which was designed to identify middle school students' strategies and advancement in understanding of four geometric concept domains (geometric spatial visualization, spatial projection, cardinal directions, and periodic patterns)…
EXPLORING PROTEIN FOLDING TRAJECTORIES USING GEOMETRIC SPANNERS
Guibas, Leonidas J.
EXPLORING PROTEIN FOLDING TRAJECTORIES USING GEOMETRIC SPANNERS D. RUSSEL and L. GUIBAS Computer describe the 3-D structure of a protein using geometric spanners -- geometric graphs with a sparse set proximities in the structure, labeling a small number of atom pairs or backbone region pairs as being
In-flight Geometric Calibration Plan
NASA Technical Reports Server (NTRS)
Jovanovic, V.
2000-01-01
This MISR in-flight Geometric Calibration (IGC) Plan describes the concept, development strategy and operational design to be used for geometric calibration of the instrument and for producing the Geometric Calibration Dataset (GCD) which is required as an input to the L1B2 standard processing.
Differential Geometric Inference in Surface Stereo
Zucker, Steven W.
Differential Geometric Inference in Surface Stereo Gang Li, Member, IEEE, and Steven W. Zucker to the matching process for slanted or curved surfaces. These errors are nonnegligible for detailed geometric to avoid such errors. A differential geometric study of smooth surfaces allows contextual information
27 CFR 19.168 - Superseding bonds.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 2011-04-01 false Superseding bonds. 19.168 Section 19.168 Alcohol... LIQUORS DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Requirements for Operations and Withdrawal Bonds § 19.168 Superseding bonds....
Creating ?-Holes through the Formation of Beryllium Bonds.
Brea, Oriana; Mó, Otilia; Yáñez, Manuel; Alkorta, Ibon; Elguero, José
2015-09-01
Through the use of ab initio theoretical models based on MP2/aug-cc-pVDZ-optimized geometries and CCSD(T)/aug-cc-pVTZ and CCSD(T)/aug-c-pVDZ total energies, it has been shown that the significant electron density rearrangements that follow the formation of a beryllium bond may lead to the appearance of a ?-hole in systems that previously do not exhibit this feature, such as CH3 OF, NO2 F, NO3 F, and other fluorine-containing systems. The creation of the ?-hole is another manifestation of the bond activation-reinforcement (BAR) rule. The appearance of a ?-hole on the F atoms of CH3 OF is due to the enhancement of the electronegativity of the O atom that participates in the beryllium bond. This atom recovers part of the charge transferred to Be by polarizing the valence density of the F into the bonding region. An analysis of the electron density shows that indeed this bond becomes reinforced, but the F atom becomes more electron deficient with the appearance of the ?-hole. Importantly, similar effects are also observed even when the atom participating in the beryllium bond is not directly attached to the F atom, as in NO2 F, NO3 F, or NCF. Hence, whereas the isolated CH3 OF, NO2 F, and NO3 F are unable to yield F???Base halogen bonds, their complexes with BeX2 derivatives are able to yield such bonds. Significant cooperative effects between the new halogen bond and the beryllium bond reinforce the strength of both noncovalent interactions. PMID:26212472
Geometrical modelling of textile reinforcements
NASA Technical Reports Server (NTRS)
Pastore, Christopher M.; Birger, Alexander B.; Clyburn, Eugene
1995-01-01
The mechanical properties of textile composites are dictated by the arrangement of yarns contained within the material. Thus, to develop a comprehensive understanding of the performance of these materials, it is necessary to develop a geometrical model of the fabric structure. This task is quite complex, as the fabric is made from highly flexible yarn systems which experience a certain degree of compressibility. Furthermore there are tremendous forces acting on the fabric during densification typically resulting in yarn displacement and misorientation. The objective of this work is to develop a methodology for characterizing the geometry of yarns within a fabric structure including experimental techniques for evaluating these models. Furthermore, some applications of these geometric results to mechanical property predictions models are demonstrated.
The verdict geometric quality library.
Knupp, Patrick Michael; Ernst, C.D. (Elemental Technologies, Inc., American Fork, UT); Thompson, David C. (Sandia National Laboratories, Livermore, CA); Stimpson, C.J. (Elemental Technologies, Inc., American Fork, UT); Pebay, Philippe Pierre
2006-03-01
Verdict is a collection of subroutines for evaluating the geometric qualities of triangles, quadrilaterals, tetrahedra, and hexahedra using a variety of metrics. A metric is a real number assigned to one of these shapes depending on its particular vertex coordinates. These metrics are used to evaluate the input to finite element, finite volume, boundary element, and other types of solvers that approximate the solution to partial differential equations defined over regions of space. The geometric qualities of these regions is usually strongly tied to the accuracy these solvers are able to obtain in their approximations. The subroutines are written in C++ and have a simple C interface. Each metric may be evaluated individually or in combination. When multiple metrics are evaluated at once, they share common calculations to lower the cost of the evaluation.
Geometric Modeling and Industrial Geometry
NSDL National Science Digital Library
The Geometric Modeling and Industrial Geometry group is part of the Institute of Discrete Mathematics and Geometry at the Vienna University of Technology. The group's goal is "to bridge the gap between academic and industrial research in geometry" by "performing application oriented fundamental research and industrial research closely connected to geometry." Its work currently emphasizes the recognition, inspection, manipulation, and design of geometric shapes. Short descriptions of the group's work and some articles are available on the academic research, covering topics such as Computational Line Geometry, Laguerre Geometry, approximation in the space of planes, the isophotic metric, and swept volumes. Visitors can also read about the group's industrial research on 3-D Computer Vision, reverse Engineering, and Industrial Inspection. The Application Areas section includes more articles and provides actual data from some of the objects it has scanned along with the resulting 3-D images.
Varying geometric compression ratio engine
Williams, G.J.
1984-05-22
An automotive engine having an automatically adjusted geometric compression ratio, wherein the charge is compressed to maximum permissible values under all throttle settings. This is achieved by a cylindrical valve carrier, raised or lowered by a screw jack, while valve stem contact is maintained by a fast acting hydraulic valve actuator. The compact arrangement provides an engine profile which is not significantly taller than a standard overhead cam engine.
Geometrical interpretation of optical absorption
Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L.; Montesinos-Amilibia, J. M.
2011-08-15
We reinterpret the transfer matrix for an absorbing system in very simple geometrical terms. In appropriate variables, the system appears as performing a Lorentz transformation in a (1 + 3)-dimensional space. Using homogeneous coordinates, we map that action on the unit sphere, which is at the realm of the Klein model of hyperbolic geometry. The effects of absorption appear then as a loxodromic transformation, that is, a rhumb line crossing all the meridians at the same angle.
An ab initio study of the N?Cl bond
NASA Astrophysics Data System (ADS)
Destro, Riccardo; Merati, Felicita; Ortoleva, Emanuele
1988-04-01
Closed-shell SCF MO calculations and geometry optimization were performed with the STO-3G, 3-21G and 6-31 G* basis sets for ten molecules containing the ?N?Cl group: ClNC, ClNO, ClNO 2, ClNCO, ClNNN, Cl 3N, Cl 2NH, ClNH 2, ClNCH 2 and ClNCH(NH 2). The hydrogenation energies were evaluated and qualitatively correlated with the R?N?Cl bond angle and the Cl gross atomic population. For the molecules considered here, the N?Cl bond is rather weak and its stability - larger for longer than for shorter N?Cl distances - increases as the R?N?Cl angle narrows. There appears to be no significant double-bond character for the shortest N?Cl bonds.
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.
1986-01-01
The present paper is concerned with an analysis of the bonding in Fe2(CO)9, taking into account the results of self-consistent-field (SCF) calculations. The basis sets used are the same as those employed in the study of Fe(CO)5 conducted by Bauschlicher and Bagus (1985). The Fe basis set starts with the 14s9p5d primitive set optimized by Wachters (1970), which is contracted to 8s4p5d. An SCF wave function, consisting of only the core electrons, was determined, and then electrons were slowly added to the virtual orbitals with the lowest eigenvalues. The conducted calculations show no direct Fe-Fe bonding, but rather bonding resulting from the bridging CO's. The bonding is found to involve both the 5 sigma and 2 pi(asterisk) orbitals of the bridging CO's.
Further Developments in Gold-stud Bump Bonding
Neher, C; Moskaleva, A; Pasner, J; Tripathi, M; Woods, M
2012-01-01
As silicon detectors in high energy physics experiments require increasingly complex assembly procedures, the availability of a wide variety of interconnect technologies provides more options for overcoming obstacles in generic R&D. Gold ball bonding has been a staple in the interconnect industry due to its ease of use and reliability. However, due to some limitations in the standard technique, alternate methods of gold-stud bonding are being developed. This paper presents recent progress and challenges faced in the development of double gold-stud bonding and 0.5 mil wire gold-stud bonding at the UC Davis Facility for Interconnect Technology. Advantages and limitations of each technique are analyzed to provide insight into potential applications for each method. Optimization of procedures and parameters is also presented.
Further developments in gold-stud bump bonding
NASA Astrophysics Data System (ADS)
Neher, C.; Lander, R. L.; Moskaleva, A.; Pasner, J.; Tripathi, M.; Woods, M.
2012-02-01
As silicon detectors in high energy physics experiments require increasingly complex assembly procedures, the availability of a wide variety of interconnect technologies provides more options for overcoming obstacles in generic R&D. Gold ball bonding has been a staple in the interconnect industry due to its ease of use and reliability. However, due to some limitations in the standard technique, alternate methods of gold-stud bonding are being developed. This paper presents recent progress and challenges faced in the development of double gold-stud bonding and 0.5 mil wire gold-stud bonding at the UC Davis Facility for Interconnect Technology. Advantages and limitations of each technique are analyzed to provide insight into potential applications for each method. Optimization of procedures and parameters is also presented.
Reflow flip-chip bonding technology for infrared detectors
NASA Astrophysics Data System (ADS)
Huang, Yue; Lin, Chun; Ye, Zhen-Hua; Ding, Rui-Jun
2015-08-01
Based on the self-alignment principle, a new reflow flip-chip bonding technology for infrared detectors is proposed. By optimizing the dimensions between the under bump metallization (UBM) and the indium bump, 10?µm tall spherical indium balls are achieved firstly. Then the technical parameters of heating temperature and surface pre-treatment are discussed. Thereafter, a new reflow flip-chip bonding technology is applied to the infrared focal plane array (IRFPA) and it results in a 6.7% of the total bad pixel percentage which is dramatically decreased compared with the thermo-compression one of 41.9%. The deduced fatigue life of the IRFPA bonded by the new reflow flip-chip bonding technology is four times longer than that of the thermo-compression one.
Geometric Effects on the Amplification of First Mode Instability Waves
NASA Technical Reports Server (NTRS)
Kirk, Lindsay C.; Candler, Graham V.
2013-01-01
The effects of geometric changes on the amplification of first mode instability waves in an external supersonic boundary layer were investigated using numerical techniques. Boundary layer stability was analyzed at Mach 6 conditions similar to freestream conditions obtained in quiet ground test facilities so that results obtained in this study may be applied to future test article design to measure first mode instability waves. The DAKOTA optimization software package was used to optimize an axisymmetric geometry to maximize the amplification of the waves at first mode frequencies as computed by the 2D STABL hypersonic boundary layer stability analysis tool. First, geometric parameters such as nose radius, cone half angle, vehicle length, and surface curvature were examined separately to determine the individual effects on the first mode amplification. Finally, all geometric parameters were allowed to vary to produce a shape optimized to maximize the amplification of first mode instability waves while minimizing the amplification of second mode instability waves. Since first mode waves are known to be most unstable in the form of oblique wave, the geometries were optimized using a broad range of wave frequencies as well as a wide range of oblique wave angles to determine the geometry that most amplifies the first mode waves. Since first mode waves are seen most often in flows with low Mach numbers at the edge of the boundary layer, the edge Mach number for each geometry was recorded to determine any relationship between edge Mach number and the stability of first mode waves. Results indicate that an axisymmetric cone with a sharp nose and a slight flare at the aft end under the Mach 6 freestream conditions used here will lower the Mach number at the edge of the boundary layer to less than 4, and the corresponding stability analysis showed maximum first mode N factors of 3.
Exploring Multiple Design Topologies Using Genetic Programming and Bond Graphs
Fernandez, Thomas
the strong topology exploration capability of genetic programming to create and evolve structures- based and GP-based. Most GA-based approaches realize topology optimization via a GA and parameterExploring Multiple Design Topologies Using Genetic Programming and Bond Graphs Zhun Fan Electrical
Bond Strength of Polymer Lightweight Aggregate Tayfun Uygunoglu,1
North Texas, University of
University, 03200 Afyonkarahisar, Turkey 2 Laboratory of Advanced Polymers & Optimized Materials (LAPOM), Department of Materials Science and Engineering and Center for Advanced Research and Technology (CART lightweight concrete (PLC), pull-out test for bond strength and compressive strength tests were performed
Geometric mean for subspace selection.
Tao, Dacheng; Li, Xuelong; Wu, Xindong; Maybank, Stephen J
2009-02-01
Subspace selection approaches are powerful tools in pattern classification and data visualization. One of the most important subspace approaches is the linear dimensionality reduction step in the Fisher's linear discriminant analysis (FLDA), which has been successfully employed in many fields such as biometrics, bioinformatics, and multimedia information management. However, the linear dimensionality reduction step in FLDA has a critical drawback: for a classification task with c classes, if the dimension of the projected subspace is strictly lower than c - 1, the projection to a subspace tends to merge those classes, which are close together in the original feature space. If separate classes are sampled from Gaussian distributions, all with identical covariance matrices, then the linear dimensionality reduction step in FLDA maximizes the mean value of the Kullback-Leibler (KL) divergences between different classes. Based on this viewpoint, the geometric mean for subspace selection is studied in this paper. Three criteria are analyzed: 1) maximization of the geometric mean of the KL divergences, 2) maximization of the geometric mean of the normalized KL divergences, and 3) the combination of 1 and 2. Preliminary experimental results based on synthetic data, UCI Machine Learning Repository, and handwriting digits show that the third criterion is a potential discriminative subspace selection method, which significantly reduces the class separation problem in comparing with the linear dimensionality reduction step in FLDA and its several representative extensions. PMID:19110492
Geometric Algebras for Euclidean Geometry
Charles G. Gunn
2015-07-10
The discussion of how to apply geometric algebra to euclidean $n$-space as been clouded by a number of conceptual misunderstandings which we first identify and resolve, based on a thorough review of crucial but largely forgotten themes from $19^{th}$ century mathematics. We then introduce the dual projectivized Clifford algebra $\\mathbf{P}(\\mathbb{R}^*_{n,0,1})$ (PGA) as the most promising homogeneous (1-up) candidate for euclidean geometry. We compare PGA and the popular 2-up model CGA (conformal geometric algebra), restricting attention to flat geometric primitives, and show that on this domain they exhibit the same formal feature set. We thereby establish that PGA is the smallest structure-preserving euclidean GA. We compare the two algebras in more detail, with respect to a number of practical criteria, including implementation of kinematics and rigid body mechanics. We then extend the comparison to include euclidean sphere primitives. We conclude that PGA provides a natural transition, both scientifically and pedagogically, between vector space models and the more complex and powerful CGA.
Geometric Tachyon and Warm Inflation
NASA Astrophysics Data System (ADS)
Bhattacharjee, Anindita; Deshamukhya, Atri
2013-03-01
The inflationary models developed in presence of a background radiation can be a solution to the reheating problem faced by common cold (isentropic) inflationary scenario. A D-brane system comprising of k Neuvo-Schwarz (NS) 5-branes with a transverse circle and BPS D3-branes with world volume parallel to the NS 5-branes, placed at a point on the transverse circle diametrically to NS 5-brane has a point of unstable equilibrium and the D3-brane has a geometric tachyonic mode associated with displacement of the brane along the circle. Cold inflationary scenario has been studied in connection with this geometric tachyon [S. Panda, M. Sami and S. Tsujikawa, Phys. Rev. D73, 023515 (2006)] where it was found that one needs a background of minimum 104 branes to realize a viable inflationary model. In this piece of work, we have tried to study a model of inflation driven by this geometric tachyon in presence of radiation. We have found that compared to the isentropic scenario, to satisfy the observational bounds, the number of background branes required in this case reduces drastically and a viable model can be obtained with even six to seven NS 5-branes in the background. In this context, we have also analyzed the non-gaussianity associated with the model and observed that the concerned parameter lies well within the observation limit.
Kanagathara, N; Marchewka, M K; Drozd, M; Gunasekaran, S; Rajakumar, P R; Anbalagan, G
2015-06-15
Single crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by the slow solvent evaporation method at room temperature. Crystalline nature of the grown crystal has been confirmed by X-ray powder diffraction studies. The optimized geometry, frequency and intensity of the vibrational bands of MBDH were obtained by the Hartree-Fock and density functional theory using B3LYP/cam-B3LYP with 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with the experimental FT-IR and FT-Raman spectral values. The obtained vibrational wavenumbers and optimized geometric parameters are found to be in good agreement with the experimental data. UV-Visible spectrum was recorded in the region 200-400 nm and the electronic properties, HOMO-LUMO energies and other related electronic parameters are calculated. The isotropic chemical shifts computed by (1)H and (13)C NMR analysis also show good agreement with experimental observation. Natural bond orbital (NBO) analysis has been performed on MBDH compound to analyze the stability of the molecule arising from hyperconjugative interactions and charge delocalization. Molecular electrostatic potential surface (MEP) has also been performed by DFT/cam-B3LYP method with 6-311++G(d,p) basis set. Differential scanning calorimetric measurements performed on the powder sample indicate the phase transition point approximately at 368 and 358K for heating and cooling, respectively. PMID:25796010
NASA Astrophysics Data System (ADS)
Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Gunasekaran, S.; Rajakumar, P. R.; Anbalagan, G.
2015-06-01
Single crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by the slow solvent evaporation method at room temperature. Crystalline nature of the grown crystal has been confirmed by X-ray powder diffraction studies. The optimized geometry, frequency and intensity of the vibrational bands of MBDH were obtained by the Hartree-Fock and density functional theory using B3LYP/cam-B3LYP with 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with the experimental FT-IR and FT-Raman spectral values. The obtained vibrational wavenumbers and optimized geometric parameters are found to be in good agreement with the experimental data. UV-Visible spectrum was recorded in the region 200-400 nm and the electronic properties, HOMO-LUMO energies and other related electronic parameters are calculated. The isotropic chemical shifts computed by 1H and 13C NMR analysis also show good agreement with experimental observation. Natural bond orbital (NBO) analysis has been performed on MBDH compound to analyze the stability of the molecule arising from hyperconjugative interactions and charge delocalization. Molecular electrostatic potential surface (MEP) has also been performed by DFT/cam-B3LYP method with 6-311++G(d,p) basis set. Differential scanning calorimetric measurements performed on the powder sample indicate the phase transition point approximately at 368 and 358 K for heating and cooling, respectively.
Gaalop—High Performance Parallel Computing Based on Conformal Geometric Algebra
NASA Astrophysics Data System (ADS)
Hildenbrand, Dietmar; Pitt, Joachim; Koch, Andreas
We present Gaalop (Geometric algebra algorithms optimizer), our tool for high-performance computing based on conformal geometric algebra. The main goal of Gaalop is to realize implementations that are most likely faster than conventional solutions. In order to achieve this goal, our focus is on parallel target platforms like FPGA (field-programmable gate arrays) or the CUDA technology from NVIDIA. We describe the concepts, current status, and future perspectives of Gaalop dealing with optimized software implementations, hardware implementations, and mixed solutions. An inverse kinematics algorithm of a humanoid robot is described as an example.
An Investigation of Bonding Mechanism in Metal Cladding by Warm Rolling
Yang, Wei
2012-02-14
Clad metals are extensively used for their multi-functionality and their optimal combination of quality and cost. Roll bonding is an effective and economic processing approach to making clad metals. This dissertation presents an experimental...
ERIC Educational Resources Information Center
Streit, Bennett R.; Geiger, David K.
2005-01-01
A computational experiment is devised for advanced inorganic laboratory course that allows the students to explore the structure and bonding patterns of ethene and some heavier analogues. The HOMO-LUMO gaps, double bond dissociation energetics, and optimized geometries of ethene, disilene, and digermene are explored.
An improved hydrogen bond potential: impact on medium resolution protein structures.
Fabiola, Felcy; Bertram, Richard; Korostelev, Andrei; Chapman, Michael S
2002-06-01
A new semi-empirical force field has been developed to describe hydrogen-bonding interactions with a directional component. The hydrogen bond potential supports two alternative target angles, motivated by the observation that carbonyl hydrogen bond acceptor angles have a bimodal distribution. It has been implemented as a module for a macromolecular refinement package to be combined with other force field terms in the stereochemically restrained refinement of macromolecules. The parameters for the hydrogen bond potential were optimized to best fit crystallographic data from a number of protein structures. Refinement of medium-resolution structures with this additional restraint leads to improved structure, reducing both the free R-factor and over-fitting. However, the improvement is seen only when stringent hydrogen bond selection criteria are used. These findings highlight common misconceptions about hydrogen bonding in proteins, and provide explanations for why the explicit hydrogen bonding terms of some popular force field sets are often best switched off. PMID:12021440
An improved hydrogen bond potential: Impact on medium resolution protein structures
Fabiola, Felcy; Bertram, Richard; Korostelev, Andrei; Chapman, Michael S.
2002-01-01
A new semi-empirical force field has been developed to describe hydrogen-bonding interactions with a directional component. The hydrogen bond potential supports two alternative target angles, motivated by the observation that carbonyl hydrogen bond acceptor angles have a bimodal distribution. It has been implemented as a module for a macromolecular refinement package to be combined with other force field terms in the stereochemically restrained refinement of macromolecules. The parameters for the hydrogen bond potential were optimized to best fit crystallographic data from a number of protein structures. Refinement of medium-resolution structures with this additional restraint leads to improved structure, reducing both the free R-factor and over-fitting. However, the improvement is seen only when stringent hydrogen bond selection criteria are used. These findings highlight common misconceptions about hydrogen bonding in proteins, and provide explanations for why the explicit hydrogen bonding terms of some popular force field sets are often best switched off. PMID:12021440
Low temperature reactive bonding
Makowiecki, D.M.; Bionta, R.M.
1995-06-23
Disclosed is a joining technique that requires no external heat source and generates very little heat. It involves the reaction of thin multilayered films deposited on faying (closely fit or joining) surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process. It can be used for joining silicon wafers and integrated circuits.
Low temperature reactive bonding
Makowiecki, D.M.; Bionta, R.M.
1995-01-17
The joining technique is disclosed that requires no external heat source and generates very little heat during joining. It involves the reaction of thin multilayered films deposited on faying surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process. 5 figures.
Silicon carbide wafer bonding by modified surface activated bonding method
NASA Astrophysics Data System (ADS)
Suga, Tadatomo; Mu, Fengwen; Fujino, Masahisa; Takahashi, Yoshikazu; Nakazawa, Haruo; Iguchi, Kenichi
2015-03-01
4H-SiC wafer bonding has been achieved by the modified surface activated bonding (SAB) method without any chemical-clean treatment and high temperature annealing. Strong bonding between the SiC wafers with tensile strength greater than 32 MPa was demonstrated at room temperature under 5 kN force for 300 s. Almost the entire wafer has been bonded very well except a small peripheral region and few voids. The interface structure was analyzed to verify the bonding mechanism. It was found an amorphous layer existed as an intermediate layer at the interface. After annealing at 1273 K in vacuum for 1 h, the bonding tensile strength was still higher than 32 MPa. The interface changes after annealing were also studied. The results show that the thickness of the amorphous layer was reduced to half after annealing.
Effects of bonding layer on the available strain measuring range of fiber Bragg gratings.
Zhang, Wei; Chen, Weimin; Shu, Yuejie; Lei, Xiaohua; Liu, Xianming
2014-02-10
Stress-induced birefringence can lead to distortion in the reflection spectra of fiber Bragg grating (FBG) sensors, thereby resulting in the loss of accuracy and stability of strain measurements. The bonding layer is a direct factor in producing stress birefringence within FBGs. To assess the impacts quantitatively, a theoretical model that links the bonding layer and the reflection spectrum was established. At the same time, the finite element method, based on the theoretical model, was used to study the relationships between characteristics of the bonding layer and reflection spectrum in detail. The analytical results indicate that high elastic modulus and mismatched Poisson's ratio of bonding layer decrease the available strain measuring range of FBGs remarkably, and that unreasonable geometric parameters of the bonding layer should be avoided. In addition, a validation experiment was conducted and experimental results proved the prediction of the theoretical analysis. It can be concluded from the results that the bonding layer is the major limiting factor for the application of surface-bonded FBG sensors in large strain measurements. The bonding materials and bonding processes used in producing FBG sensors deserve serious consideration. PMID:24663267
[SIBSytem: innovation for bracket bonding?].
Moreau, Alexis
2013-06-01
The orthodontic bracket placement has known two major improvements these last fifty years: first with the ability of bonding brackets directly on the enamel (Newmann 1965); second with the indirect bonding procedure introduced by Silvermann and Cohen in 1972. If we put aside the technological evolutions of bonding materials (brackets and adhesives), few refinements have occurred regarding the protocols in this period of time. Furthermore, direct bonding procedure seems to be used by a majority of orthodontists despite the rapidity, accuracy and ergonomics promised by indirect bonding protocol. The main originality of the system detailed in this article is to bond orthodontic brackets in a virtually predetermined position with indirect bonding advantages but with the efficiency of direct bonding because the adhesive is applied directly on the bracket base without pre-bonding necessity. This innovation has been allowed by the use of up-to-date CFAO technology. The article first describes the two components of the SIBSystem (SIBClip and SIBTray) and details the manufacturing stages. The clinical use is then evoked as well as the cautions and limits of this innovative bonding system. PMID:23719248
Solder extrusion pressure bonding process and bonded products produced thereby
NASA Astrophysics Data System (ADS)
Beavis, L. C.; Karnowsky, M. M.; Yost, F. G.
1990-04-01
The production of soldered joints are highly reliable and capable of surviving 10,000 thermal cycles between about -40 and 110 C. The process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.
NASA Technical Reports Server (NTRS)
Progar, D.
1979-01-01
Adhesive systems which could be used to bond composite-to-composite, composite-to-titanium, and honeycomb sandwich structures with operational capability at 589K for a minimum of 125 hours were evaluated. Evaluations were based on mechanical property tests such as lap shear and flatwise tensile and on processability. Quasi-isotropic Celion 6000/PMR-15 composite adherend was used to construct lap shear and flatwise tensile specimens. Hexcel's HRH-327-3/16-6.0 glass polyimide honeycomb core was also utilized in the flatwise tensile specimens. Numerous processing variations were also studied that led to selected cure cycles for each adhesive. Shear specimens having either 12 mm or 75 mm overlaps were used to determine the effect of bond size on processability and lap shear properties. The data indicate that processing of FM-34, FM-34B-18, LARC-13 and NRO56X can be achieved using a cure compatible with the composite adherend. No significant differences in mechanical properties were observed among the three adhesive systems and all three are suitable candidates for 589K/125 hour service.
Modeling of Tab Inner Lead Bonding Process.
NASA Astrophysics Data System (ADS)
Kim, Young-Gon
Model based manufacturing process design leads to time and cost saving benefits. Modeling of the TAB inner lead bonding process is the major objective of this research. Both analytical investigation and experimental observations have been used to model the process. For this research, three set of experiments have been performed. 4 -mil pitch 328 leads beam tape and corresponding testing die were used for these experiments. The identification of the parameter main effects on the bump-lead bond strength and the bump-pad adhesion strength were the major objective of the experiments. The idea of the modeling the nominally flat surface has come from the Greenwood and Williamson's asperity based model. Here, the asperity control volume and the relative density of the asperity control volume have been newly defined to fit the TAB model. The theory of large deformation has come from the hot isostatic pressing (HIP) process. Driving forces for TAB geometry have been derived and modifications were made on the densification equations for hot isostatic pressing. In this study, the final relative density of the asperity control volume has been defined as the theoretical index of the bond quality. A constitutive equation relating experimentally measured pull strength to theoretically predicted relative density has been obtained from a least square error fit to the collected data. Finally, the accuracy of the developed model has been tested by experiments, and proved to be within 2% error at the optimal process levels.
Decentralized nonlinear optimal excitation control
Lu, Q.; Sun, Y. [Tsinghua Univ., Beijing (China). Dept. of Electrical Engineering] [Tsinghua Univ., Beijing (China). Dept. of Electrical Engineering; Xu, Z.; Mochizuki, T. [Kyushu Inst. of Tech., Kitakyushu (Japan). Dept. of Electrical Engineering] [Kyushu Inst. of Tech., Kitakyushu (Japan). Dept. of Electrical Engineering
1996-11-01
A design method to lay emphasis on differential geometric approach for decentralized nonlinear optimal excitation control of multimachine systems is suggested in this paper. The control law achieved is implemented via purely local measurements. Moreover, it is independent of the parameters of power networks. Simulations are performed on a six-machine system. It has been demonstrated that the nonlinear optimal excitation control could adapt to the conditions under large disturbances. Besides, this paper has verified that the optimal control in the sense of LQR principle for the linearized system is equivalent to an optimal control in the sense of a quasi-quadratic performance index for the primitive nonlinear control system.
Convex Optimization Convex Optimization
Masci, Frank
Convex Optimization #12;#12;Convex Optimization Stephen Boyd Department of Electrical Engineering Cataloguing-in-Publication data Boyd, Stephen P. Convex Optimization / Stephen Boyd & Lieven Vandenberghe p. cm. Includes bibliographical references and index. ISBN 0 521 83378 7 1. Mathematical optimization. 2
The source of chemical bonding.
Needham, Paul
2014-03-01
Developments in the application of quantum mechanics to the understanding of the chemical bond are traced with a view to examining the evolving conception of the covalent bond. Beginning with the first quantum mechanical resolution of the apparent paradox in Lewis's conception of a shared electron pair bond by Heitler and London, the ensuing account takes up the challenge molecular orbital theory seemed to pose to the classical conception of the bond. We will see that the threat of delocalisation can be overstated, although it is questionable whether this should be seen as reinstating the issue of the existence of the chemical bond. More salient are some recent developments in a longstanding discussion of how to understand the causal aspects of the bonding interaction--the nature of the force involved in the covalent link--which are taken up in the latter part of the paper. PMID:24984444
Optimization of the geometry of the diphenylamine molecule by semiempirical quantum chemical methods
Pankratov, A.N.; Mushtakova, S.P.; Gribov, L.A.
1986-03-01
Available data on experimental study of the geometry of the diphenylamine molecule (I) in solution and in the crystal are fragmentary and not always reliable. Previously, they did a conformational analysis of molecule I using the atom-atom potential method. In order to refine the geometric parameters found for molecule I, optimization of its geometry is provided in the paper using the CNDO/2, INDO, MINDO/3 methods with the use of programs for the BESM-6 computer which are part of the VIKING program set. The angles of rotation for the phenyl rings relative to the CNC plane, the bond angles C/sub 2/N/sub 7/C/sub 8/ and C/sub 2/N/sub 7/H/sub 19/, and also the dihedral angle H/sub 19/N/sub 7/C/sub 8/C/sub 9/ were subjected to optimization. For any set of values for the indicated parameters, the bond angle C/sub 8/N/sub 7/H/sub 19/ is determined unambiguously. The results of the calculations are evidence that the MINDO/3 method is not suitable for optimization of the geometry for molecules of the indicated series; in particular, it leads to much too high a value for the CNC angles (135.9/sup 0/). The CNDO/2 method reproduces well the real value of the CNC angle (124.1/sup 0/) and confirms the known pyrimidal character of the nitrogen atom, the sum of the bond angles of which proved to be equal to 353.6/sup 0/. The calculation in the INDO approximation successfully gives the basic characteristics of the molecular geometry of (I); according to this approximation, the CNC angle is equal to 123.2/sup 0/, the CNH angles are equal to 118.0 and 118.8/sup 0/, the sum of the angles for the nitrogen atom is 360.0/sup 0/.
NASA Astrophysics Data System (ADS)
Backman, M.; Juslin, N.; Nordlund, K.
2012-09-01
We develop an analytic bond order potential for modelling of gold. The bond order formalism includes bond angularity and offers an alternative approach to the embedded atom type potentials frequently used to describe metallic bonding. The advantage of the developed potential is that it can be extended to describe interactions with covalent materials. Experimental and ab initio data of gold properties is used to fit the potential and a good description of bulk and defect properties is achieved. We use the potential to simulate melting of nanoclusters and find that the experimentally observed size dependent melting behaviour is reproduced qualitatively.
Bond failure patterns in vivo.
Linklater, Rognvald A; Gordon, Peter H
2003-05-01
The aim of this study was to identify the presence and pattern of differences in bond failure between tooth types in vivo when bonding orthodontic brackets with the no-mix orthodontic composite adhesive Right-On. In vivo bond failure for a single operator was recorded for 108 consecutive patients undergoing fixed-appliance orthodontic treatment. The bond failure data were analyzed by survival analysis. Time to first failure or censorship was recorded for each bonded attachment. Overall failure in the sample matched previous clinical studies but conflicted with previous ex vivo bond strength data. Mandibular and posterior teeth had significantly higher rates of failure than did maxillary and anterior teeth. The type of attachment used had a significant effect on bond survival. The results of this study confirm that in vivo bond survival is not uniform for all teeth. Comparisons between the findings of this study and those of a previous ex vivo study by the same authors failed to validate ex vivo bond strength testing as clinically relevant. PMID:12750672
Geometric phases in quantum information
Erik Sjöqvist
2015-03-16
The rise of quantum information science has opened up a new venue for applications of the geometric phase (GP), as well as triggered new insights into its physical, mathematical, and conceptual nature. Here, we review this development by focusing on three main themes: the use of GPs to perform robust quantum computation, the development of GP concepts for mixed quantum states, and the discovery of a new type of topological phases for entangled quantum systems. We delineate the theoretical development as well as describe recent experiments related to GPs in the context of quantum information.
SQCD Vacua and Geometrical Engineering
Tatar, Radu; Wetenhall, Ben [Department of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX (United Kingdom)
2008-11-23
We consider the geometrical engineering constructions for the N = 1 SQCD vacua. After one T-duality, these geometries with wrapped D5 branes become N = 1 brane configurations with NS-branes and D4-branes. After performing a flop, the geometries contain branes, antibranes and branes wrapped on non-holomorphic cycles. The various tachyon condensations between pairs of wrapped D5 branes and anti-D5 branes together with deformations of the cycles give rise to a variety of supersymmetric and metastable non-supersymmetric vacua.
Geometric phases in quantum information
Erik Sjöqvist
2015-10-07
The rise of quantum information science has opened up a new venue for applications of the geometric phase (GP), as well as triggered new insights into its physical, mathematical, and conceptual nature. Here, we review this development by focusing on three main themes: the use of GPs to perform robust quantum computation, the development of GP concepts for mixed quantum states, and the discovery of a new type of topological phases for entangled quantum systems. We delineate the theoretical development as well as describe recent experiments related to GPs in the context of quantum information.
Graphene with geometrically induced vorticity
Jiannis K. Pachos; Michael Stone; Kristan Temme
2008-03-26
At half filling, the electronic structure of graphene can be modelled by a pair of free two-dimensional Dirac fermions. We explicitly demonstrate that in the presence of a geometrically induced gauge field, an everywhere-real Kekule modulation of the hopping matrix elements can correspond to a non-real Higgs field with non-trivial vorticity. This provides a natural setting for fractionally charged vortices with localized zero modes. For fullerene-like molecules we employ the index theorem to demonstrate the existence of six low-lying states that do not depend strongly on the Kekule-induced mass gap.
SQCD Vacua and Geometrical Engineering
Radu Tatar; Ben Wetenhall
2007-11-16
We consider the geometrical engineering constructions for the N = 1 SQCD vacua recently proposed by Giveon and Kutasov. After one T-duality, the geometries with wrapped D5 branes become N = 1 brane configurations with NS branes and D4 branes. The field theories encoded by the geometries contain extra massive adjoint fields for the flavor group. After performing a flop, the geometries contain branes, antibranes and branes wrapped on non-holomorphic cycles. The various tachyon condensations between pairs of wrapped D5 branes and anti D5 branes together with deformations of the cycles give rise to a variety of supersymmetric and metastable non-supersymmetric vacua.
Spacetime physics with geometric algebra
NASA Astrophysics Data System (ADS)
Hestenes, David
2003-07-01
This is an introduction to spacetime algebra (STA) as a unified mathematical language for physics. STA simplifies, extends, and integrates the mathematical methods of classical, relativistic, and quantum physics while elucidating geometric structure of the theory. For example, STA provides a single, matrix-free spinor method for rotational dynamics with applications from classical rigid body mechanics to relativistic quantum theory—thus significantly reducing the mathematical and conceptual barriers between classical and quantum mechanics. The entire physics curriculum can be unified and simplified by adopting STA as the standard mathematical language. This would enable early infusion of spacetime physics and give it the prominent place it deserves in the curriculum.
Crystal-Like geometric modeling
Landreneau, Eric Benjamin
2006-08-16
of this thesis. Modeling of crystal formation can be approached from a near-atomic level, such as in Kim?s ice crystal work[10]. However, this thesis focuses on geometric modeling of large scale crystal-like shapes, such as are seen in gemstones or geodes... example of this fractal geometry can commonly be seen in crystals and gemstones. The atomic structure of these minerals lends itself to a recursive structure. A simple example of this recursive property is seen in the calcite crystal. As calcite...
Geometric analysis of wing sections
NASA Technical Reports Server (NTRS)
Chang, I.-CHUNG; Torres, Francisco J.; Tung, Chee
1995-01-01
This paper describes a new geometric analysis procedure for wing sections. This procedure is based on the normal mode analysis for continuous functions. A set of special shape functions is introduced to represent the geometry of the wing section. The generators of the NACA 4-digit airfoils were included in this set of shape functions. It is found that the supercritical wing section, Korn airfoil, could be well represented by a set of ten shape functions. Preliminary results showed that the number of parameters to define a wing section could be greatly reduced to about ten. Hence, the present research clearly advances the airfoil design technology by reducing the number of design variables.
Geometric Particle Swarm Optimization for the Sudoku Puzzle
Togelius, Julian
) is a recently introduced generalization of traditional particle swarm op- timization (PSO) that applies to all to continuous search spaces. Although a version of PSO for binary search spaces has been defined [7], all at- tempts to extend PSO to richer spaces, such as, for example, combinatorial spaces, have had no real
Chemical Sensor Array Optimization: Geometric and Information Theoretic Approaches
Pearce, Tim C.
of commercial products, such as foods, beverages, and cosmetics. Even though a large number of compa- nies exist-VCH: Weinheim Germany, eds. T.C. Pearce, S. S. Schiffman, H. T. Nagle, J. W. Gardner, 2002. 1. The Need range of detection tasks from quality control of various food products to medical diagnosis. Clearly
Optimized state independent entanglement detection based on geometrical threshold criterion
Wieslaw Laskowski; Christian Schwemmer; Daniel Richart; Lukas Knips; Tomasz Paterek; Harald Weinfurter
2013-08-29
Experimental procedures are presented for the rapid detection of entanglement of unknown arbitrary quantum states. The methods are based on the entanglement criterion using accessible correlations and the principle of correlation complementarity. Our first scheme essentially establishes the Schmidt decomposition for pure states, with few measurements only and without the need for shared reference frames. The second scheme employs a decision tree to speed up entanglement detection. We analyze the performance of the methods using numerical simulations and verify them experimentally for various states of two, three and four qubits.
Optimal Navigation and Object Finding without Geometric Maps or Localization
LaValle, Steven M.
such as surveillance, search- and-rescue, fire-fighting, law enforcement, and re- mote visual presence. Classical to use it without needing a global reference frame. Simulation results are also shown to demonstrate how
Application of separable programming to optimization by geometric programming
Humber, Joseph Barker
1971-01-01
) if it appears as a constraint and by r(X) if it i appears in the objective function. In general, then, equations (4-6), (4-7), and (4-8) can be written as follows: (4-9) r. j j j kj kj =0 A ij~ j( kj kij =0 rj j kj kj =0 r. 1 kj =0 where 17 kiJ.... 5545 1. 4290 1. 0575 2 16. 4616 0. 7714 0. 5545 1. 4290 1. 0575 3 18. 1497 0. 7714 0. 7233 1. 4290 1. 0575 4 229. 3433 0. 7714 0. 7233 179. 2275 1, 0575 1000 0 v(6) = 87. 3775 System g, (T) t2 t. 3 t4 1 87. 3773 4. 9166 2. 8418 7. 2814 5. 0836 2...
Parameterization and Geometric Optimization of Balloon Launched Sensorcraft for Atmospheric
Sóbester, András
, England SO17 1BJ, United Kingdom We present a method for the payload centric automated design measurements of atmospheric phenomena with a variety of payloads. A bespoke airframe design is generated, that relies heavily on rapid prototyp- ing, allows for rapid realization of the aircraft design. This allows
GEOMETRIC OPTIMIZATION OF RADIATIVE ENCLOSURES THROUGH NONLINEAR PROGRAMMING
Morton, David
& Francis 1040-7790/03 $12.00 + .00 DOI: 10.1080/10407790390122050 203 #12;convection problems; examples include the design of heat exchangers [4, 5], elec- tronics cooling systems [6], and turbine blades [7
Bond tests of fiberglass-reinforced plastic bars in concrete
Larralde, J.; Silva-Rodriquez, R.; Burdette, J.; Harris, B. (Drexel Univ., Philadelphia, PA (United States). Civil and Architectural Engineering Dept.)
1994-07-01
Fiberglass Reinforced Plastic (FRP) bars for concrete reinforcement have been commercially available for several years. The main advantage of such bar relative to the conventional steel reinforcing bars is their resistance to corrosion. The reinforced plastic bars are slightly different from the conventional steel bars both geometrically and mechanically. Thus, research is needed to understand their behavior and to be able to use them in concrete reinforcement with adequate reliability. Bond strength of reinforced plastic bars in concrete is one of the mechanical and behavioral differences with the steel bars. This paper presents the results of pullout and beam tests conducted to determine the bond stress-slip behavior of FRP bars in concrete.
Fatigue strength of a single lap joint SPR-bonded
NASA Astrophysics Data System (ADS)
Di Franco, G.; Fratini, L.; Pasta, A.
2011-05-01
In the last years, hybrid joints, meaning with this the joints which consist in combining a traditional mechanical joint to a layer of adhesive, are gradually attracting the attention of various sectors of the construction of vehicles and transportation industries, for their better performance compared to just mechanical joints (self-piercing riveting SPR, riveting, and so on) or just to bonded joints. The paper investigates the fatigue behavior of a single lap joint self-piercing riveted (SPR) and bonded throughout fatigue tests. The considered geometric configuration allowed the use of two rivets placed longitudinally; an epoxy resin was used as adhesive. In the first part of the work static characterization of the joints was carried out through tensile tests. Then fatigue tests were made with the application of different levels of load. The fatigue curves were also obtained at the varying the distance between the two rivets in order to better assess the joint strength for a given length of overlap.
Indirect orthodontic bonding - a modified technique for improved efficiency and precision
Nojima, Lincoln Issamu; Araújo, Adriele Silveira; Alves, Matheus
2015-01-01
INTRODUCTION: The indirect bonding technique optimizes fixed appliance installation at the orthodontic office, ensuring precise bracket positioning, among other advantages. In this laboratory clinical phase, material and methods employed in creating the transfer tray are decisive to accuracy. OBJECTIVE: This article describes a simple, efficient and reproducible indirect bonding technique that allows the procedure to be carried out successfully. Variables influencing the orthodontic bonding are analyzed and discussed in order to aid professionals wishing to adopt the indirect bonding technique routinely in their clinical practice. PMID:26154464
Enthalpy-entropy compensation in biomolecular halogen bonds measured in DNA junctions.
Carter, Megan; Voth, Andrea Regier; Scholfield, Matthew R; Rummel, Brittany; Sowers, Lawrence C; Ho, P Shing
2013-07-23
Interest in noncovalent interactions involving halogens, particularly halogen bonds (X-bonds), has grown dramatically in the past decade, propelled by the use of X-bonding in molecular engineering and drug design. However, it is clear that a complete analysis of the structure-energy relationship must be established in biological systems to fully exploit X-bonds for biomolecular engineering. We present here the first comprehensive experimental study to correlate geometries with their stabilizing potentials for fluorine (F), chlorine (Cl), bromine (Br), or iodine (I) X-bonds in a biological context. For these studies, we determine the single-crystal structures of DNA Holliday junctions containing halogenated uracil bases that compete X-bonds against classic hydrogen bonds (H-bonds), estimate the enthalpic energies of the competing interactions in the crystal system through crystallographic titrations, and compare the enthalpic and entropic energies of bromine and iodine X-bonds in solution by differential scanning calorimetry. The culmination of these studies demonstrates that enthalpic stabilization of X-bonds increases with increasing polarizability from F to Cl to Br to I, which is consistent with the ?-hole theory of X-bonding. Furthermore, an increase in the X-bonding potential is seen to direct the interaction toward a more ideal geometry. However, the entropic contributions to the total free energies must also be considered to determine how each halogen potentially contributes to the overall stability of the interaction. We find that bromine has the optimal balance between enthalpic and entropic energy components, resulting in the lowest free energy for X-bonding in this DNA system. The X-bond formed by iodine is more enthalpically stable, but this comes with an entropic cost, which we attribute to crowding effects. Thus, the overall free energy of an X-bonding interaction balances the stabilizing electrostatic effects of the ?-hole against the competing effects on the local structural dynamics of the system. PMID:23789744
Geometric solitons of Hamiltonian flows on manifolds
Song, Chong; Sun, Xiaowei; Wang, Youde
2013-12-15
It is well-known that the LIE (Locally Induction Equation) admit soliton-type solutions and same soliton solutions arise from different and apparently irrelevant physical models. By comparing the solitons of LIE and Killing magnetic geodesics, we observe that these solitons are essentially decided by two families of isometries of the domain and the target space, respectively. With this insight, we propose the new concept of geometric solitons of Hamiltonian flows on manifolds, such as geometric Schrödinger flows and KdV flows for maps. Moreover, we give several examples of geometric solitons of the Schrödinger flow and geometric KdV flow, including magnetic curves as geometric Schrödinger solitons and explicit geometric KdV solitons on surfaces of revolution.
Hydrogen-bond-driven controlled molecular marriage in covalent cages.
Acharyya, Koushik; Mukherjee, Partha Sarathi
2014-02-01
A supramolecular approach that uses hydrogen-bonding interaction as a driving force to accomplish exceptional self-sorting in the formation of imine-based covalent organic cages is discussed. Utilizing the dynamic covalent chemistry approach from three geometrically similar dialdehydes (A, B, and D) and the flexible triamine tris(2-aminoethyl)amine (X), three new [3+2] self-assembled nanoscopic organic cages have been synthesized and fully characterized by various techniques. When a complex mixture of the dialdehydes and triamine X was subjected to reaction, it was found that only dialdehyde B (which has OH groups for H-bonding) reacted to form the corresponding cage B3X2 selectively. Surprisingly, the same reaction in the absence of aldehyde B yielded a mixture of products. Theoretical and experimental investigations are in complete agreement that the presence of the hydroxyl moiety adjacent to the aldehyde functionality in B is responsible for the selective formation of cage B3X2 from a complex reaction mixture. This spectacular selection was further analyzed by transforming a nonpreferred (non-hydroxy) cage into a preferred (hydroxy) cage B3X2 by treating the former with aldehyde B. The role of the H-bond in partner selection in a mixture of two dialdehydes and two amines has also been established. Moreover, an example of unconventional imine bond metathesis in organic cage-to-cage transformation is reported. PMID:24382644
Explosive bonding of 316L to C18150 CuCrZr alloy for ITER applications.
Puskar, Joseph David; Butler, Don J.; Goods, Steven Howard; Brasher, Dave G.
2010-10-01
Recent developments in the ITER experimental fusion reactor require that a 316L stainless steel substructure be bonded to a precipitation strengthened CuCrZr heat sink alloy, C18150. This bond defines the cooling water pressure boundary. Given the importance of this interface, a variety of experiments with fusion welding and solid-state joining techniques have been performed. Analysis of the joints includes mechanical measurements of bond strength and microstructural analysis using optical and electron microscopy techniques. A particular emphasis was placed on the mechanical properties of the CuCrZr, since it undergoes additional thermal processing and cannot be solutionized and aged hardened per standard heat treatments. It was determined that the explosion bonding, of all the techniques examined, maximized the residual mechanical strength of the CuCrZr. The bonding parameters were optimized to minimize the amount of mixing and porosity at the interface. The details of these results and the optimization will be discussed.
Explosive bonding of plates with diffusion barrier interfaces
NASA Astrophysics Data System (ADS)
Joshi, V. S.; Banks, M. L.; Krebsbach, J.
2000-04-01
Composite plates, with and without, "waves" were made using improved explosive welding techniques. Oriented heat treatment of one surface of a steel-titanium composite introduces brittle intermetallic material at the specific interface. Currently, we are investigating methods to minimize this layer. While "waveless" interfaces revealed minimum intermetallic material; failure of the bond during ballistic impact necessitated production of a semi-compatible diffusion barrier using a fine layer of pure metal. Methods of producing composite plates with different interlayer materials and the effect of variables in optimizing the bond quality is presented.
Bonding and Integration Technologies for Silicon Carbide Based Injector Components
NASA Technical Reports Server (NTRS)
Halbig, Michael C.; Singh, Mrityunjay
2008-01-01
Advanced ceramic bonding and integration technologies play a critical role in the fabrication and application of silicon carbide based components for a number of aerospace and ground based applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. Ceramic to ceramic diffusion bonding and ceramic to metal brazing technologies are being developed for this injector application. For the diffusion bonding, titanium interlayers (PVD and foils) were used to aid in the joining of silicon carbide (SiC) substrates. The influence of such variables as surface finish, interlayer thickness (10, 20, and 50 microns), processing time and temperature, and cooling rates were investigated. Microprobe analysis was used to identify the phases in the bonded region. For bonds that were not fully reacted an intermediate phase, Ti5Si3Cx, formed that is thermally incompatible in its thermal expansion and caused thermal stresses and cracking during the processing cool-down. Thinner titanium interlayers and/or longer processing times resulted in stable and compatible phases that did not contribute to microcracking and resulted in an optimized microstructure. Tensile tests on the joined materials resulted in strengths of 13-28 MPa depending on the SiC substrate material. Non-destructive evaluation using ultrasonic immersion showed well formed bonds. For the joining technology of brazing Kovar fuel tubes to silicon carbide, preliminary development of the joining approach has begun. Various technical issues and requirements for the injector application are addressed.
Thermoplastic polymeric adhesive for structural bonding applications for orthopaedic devices
Devanathan, D.; King, R.; Swarts, D.; Lin, S.; Ramani, K.; Tagle, J.
1994-12-31
The orthopaedics industry has witnessed tremendous growth in recent years primarily due to the introduction of high performance, porous coated implants. These devices have eliminated the need for the use of bone cement for in vivo implant fixation, replacing it with the ingrowth of bone into the porous surfaces. The metallurgical bonding processes used for attaching the porous to the implant body introduce some undesirable effect i.e., the reduction of the fatigue strength of the implant due to the ``notches`` created and also due to the high temperature exposure during the sintering operations. This paper describes the development of a thermoplastic polymeric adhesive based structural bonding technique. The high performance polymeric adhesive is fully characterized with respect to its intended application. The design of the porous layer is optimized to achieve a reliable bond to the implant. A thermal heating/cooling process was developed to control the final polymer morphology. Static and fatigue tests were conducted to fully characterize the adhesive bond strength. A ring shear test method was developed to determine the shear strength of the bond interface. Besides the characterization of the adhesive bond, the joints will be analyzed using finite element models. The correlation between the analytical models and the
NASA Astrophysics Data System (ADS)
Li, Xin; Yang, Mengshi; Shi, Xiao; Chu, Xiuxiang; Chen, Liang; Wu, Qiang; Wang, Yueyue
2015-05-01
The geometric structures, hydrogen bond types, IR spectra and nonlinear optical properties of chitosan oligosaccharide (degree of polymerization 2-5) are studied by density-functional theory (DFT) at B3LYP/6-31+G(d) level. We have analyzed the statistics of relationship between IR spectra and bond lengths, and angles of amino, hydroxyl. The results show that: (1) the active groups C3-OH, C6-OH and -NH2 can form intramolecular hydrogen bond in chitosan oligosaccharide; (2) the IR spectra of three active groups have size effect in growth process, however, its IR intensity increases significantly and IR frequencies are red shifted obviously when the active hydroxyl form hydrogen bonds, because the bond length of active hydroxyl becomes longer; (3) the effect of hydrogen bond on intensity and frequency of the three vibration mode of amino is the main factor and complication. The paper also provides the nonlinear optical properties of chitosan oligosaccharide. The reason why hydrogen bond can make an appreciable difference to IR spectra, and the nonlinear optical properties of chitosan oligosaccharide are discussed. This research has important significance in the characterization of chitosan oligosaccharide, the properties of chitosan material and hydrogen bond by infrared spectroscopy.
Ultrasonic phosphate bonding of nanoparticles.
Bassett, David C; Merle, Geraldine; Lennox, Bruce; Rabiei, Reza; Barthelat, François; Grover, Liam M; Barralet, Jake E
2013-11-01
Low intensity ultrasound-induced radicals interact with surface adsorbed orthophosphate to bond nanoparticles with high mechanical strength and surface area. Dissimilar materials could be bonded to form robust metallic, ceramic, and organic composite microparticles. 3D nanostructures of a hydrated and amorphous electrocatalyst with carbon nanotubes were also constructed which exceeded the resistance-limited efficiency of 2D electrodes. PMID:23893468
Stress Distribution in Bonded Joints
F. Erdogan; M. Ratwani
1971-01-01
The stress distribution in plates bonded through stepped joints is analyzed. The problem is solved under the assumption of gen eralized plane stress. A series of examples are worked out on specific plate geometries and material combinations. The effect of step ends is separately studied. As a limiting case, the solution for bonded plates with a smoothly tapered joint is
Microwave bonding of MEMS component
NASA Technical Reports Server (NTRS)
Barmatz, Martin B. (Inventor); Mai, John D. (Inventor); Jackson, Henry W. (Inventor); Budraa, Nasser K. (Inventor); Pike, William T. (Inventor)
2005-01-01
Bonding of MEMs materials is carried out using microwave. High microwave absorbing films are placed within a microwave cavity, and excited to cause selective heating in the skin of the material. This causes heating in one place more than another. Thereby minimizing the effects of the bonding microwave energy.
Computational Chemistry of Adhesive Bonds
NASA Technical Reports Server (NTRS)
Phillips, Donald H.
1999-01-01
This investigation is intended to determine the electrical mechanical, and chemical properties of adhesive bonds at the molecular level. The initial determinations will be followed by investigations of the effects of environmental effects on the chemistry and properties of the bond layer.
Tradeoff between delay and area in gate sizing using Geometric Programming
Gracieli Posser; Guilherme Flach; Gustavo Wilke; Ricardo Reis
2012-01-01
A study about the tradeoff between delay and area (power) is presented in this work considering circuit gate sizing. We use a gate sizing tool based on Geometric Programming (GP), where delay is calculated by Elmore delay model. The optimization can be done targeting both delay and area (power) minimization. Tests were performed mapping ISCAS'85 benchmark circuits for 45nm technology.
Geometric discord for non-X states
NASA Astrophysics Data System (ADS)
Liu, Chen; Dong, Yu-Li; Zhu, Shi-Qun
2014-06-01
The level surfaces of geometric discord for a class of two-qubit non-X states are investigated when the Bloch vectors are in arbitrary directions. The level surfaces of constant geometric discord are formed by three intersecting open tubes along three orthogonal directions. When Bloch vectors increase, the tubes along one or two directions shrink towards the center and may either totally disappear or the open tubes may become closed tubes when the Bloch vectors reach a critical value. In the generalized amplitude damping channel, the evolution of geometric discord shows double sudden changes when the parameter ? increases. In the phase damping channel, the freezing phenomenon of geometric discord also exists.
Multiqubit symmetric states with high geometric entanglement
Martin, J.; Bastin, T. [Institut de Physique Nucleaire, Atomique et de Spectroscopie, Universite de Liege, B-4000 Liege (Belgium); Giraud, O. [Universite de Toulouse, UPS, Laboratoire de Physique Theorique (IRSAMC), F-31062 Toulouse (France); CNRS, LPT (IRSAMC), F-31062 Toulouse (France); Universite Paris-Sud, LPTMS, UMR8626, Ba circumflex t. 100, Universite Paris-Sud, F-91405 Orsay (France); CNRS, LPTMS, UMR8626, Ba circumflex t. 100, Universite Paris-Sud, F-91405 Orsay (France); Braun, P. A. [Fachbereich Physik, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany); Institute of Physics, Saint-Petersburg University, 198504 Saint-Petersburg (Russian Federation); Braun, D. [Universite de Toulouse, UPS, Laboratoire de Physique Theorique (IRSAMC), F-31062 Toulouse (France); CNRS, LPT (IRSAMC), F-31062 Toulouse (France)
2010-06-15
We propose a detailed study of the geometric entanglement properties of pure symmetric N-qubit states, focusing more particularly on the identification of symmetric states with a high geometric entanglement and how their entanglement behaves asymptotically for large N. We show that much higher geometric entanglement with improved asymptotical behavior can be obtained in comparison with the highly entangled balanced Dicke states studied previously. We also derive an upper bound for the geometric measure of entanglement of symmetric states. The connection with the quantumness of a state is discussed.
Quantum Confinement in Hydrogen Bond
Santos, Carlos da Silva dos; Ricotta, Regina Maria
2015-01-01
In this work, the quantum confinement effect is proposed as the cause of the displacement of the vibrational spectrum of molecular groups that involve hydrogen bonds. In this approach the hydrogen bond imposes a space barrier to hydrogen and constrains its oscillatory motion. We studied the vibrational transitions through the Morse potential, for the NH and OH molecular groups inside macromolecules in situation of confinement (when hydrogen bonding is formed) and non-confinement (when there is no hydrogen bonding). The energies were obtained through the variational method with the trial wave functions obtained from Supersymmetric Quantum Mechanics (SQM) formalism. The results indicate that it is possible to distinguish the emission peaks related to the existence of the hydrogen bonds. These analytical results were satisfactorily compared with experimental results obtained from infrared spectroscopy.
Quantum Confinement in Hydrogen Bond
Carlos da Silva dos Santos; Elso Drigo Filho; Regina Maria Ricotta
2015-02-09
In this work, the quantum confinement effect is proposed as the cause of the displacement of the vibrational spectrum of molecular groups that involve hydrogen bonds. In this approach the hydrogen bond imposes a space barrier to hydrogen and constrains its oscillatory motion. We studied the vibrational transitions through the Morse potential, for the NH and OH molecular groups inside macromolecules in situation of confinement (when hydrogen bonding is formed) and non-confinement (when there is no hydrogen bonding). The energies were obtained through the variational method with the trial wave functions obtained from Supersymmetric Quantum Mechanics (SQM) formalism. The results indicate that it is possible to distinguish the emission peaks related to the existence of the hydrogen bonds. These analytical results were satisfactorily compared with experimental results obtained from infrared spectroscopy.
Halogen bonding in supramolecular synthesis.
Aakeröy, Christer B; Spartz, Christine L
2015-01-01
Supramolecular synthesis is typically limited to one-pot reactions because of the reversibility of non-covalent bonds, and to overcome this restriction we need to be able to rank the relative structural importance of such interactions and build synthetic methods to utilize synthons which can operate side-by-side without interference. Halogen bonds have characteristics (strength and directionality) which potentially make them prime candidates as critical components of effective, transferable, and versatile supramolecular synthetic strategies. In this chapter, several halogen-bond driven crystal engineering strategies for the assembly of specific architectures in molecular solids are described in detail, and the utility of halogen bonds for the synthesis of co-crystals are addressed. Finally, the structural compatibility or competition between of halogen- and hydrogen bonds in the context of supramolecular synthesis are examined. PMID:25467531
Social bonding: regulation by neuropeptides
Lieberwirth, Claudia; Wang, Zuoxin
2014-01-01
Affiliative social relationships (e.g., among spouses, family members, and friends) play an essential role in human society. These relationships affect psychological, physiological, and behavioral functions. As positive and enduring bonds are critical for the overall well-being of humans, it is not surprising that considerable effort has been made to study the neurobiological mechanisms that underlie social bonding behaviors. The present review details the involvement of the nonapeptides, oxytocin (OT), and arginine vasopressin (AVP), in the regulation of social bonding in mammals including humans. In particular, we will discuss the role of OT and AVP in the formation of social bonds between partners of a mating pair as well as between parents and their offspring. Furthermore, the role of OT and AVP in the formation of interpersonal bonding involving trust is also discussed. PMID:25009457
27 CFR 25.94 - Strengthening bonds.
Code of Federal Regulations, 2010 CFR
2010-04-01
...bonds. (a) Requirement. When the penal sum of the brewer's bond (calculated...give a strengthening bond in sufficient penal sum if the surety is the same as on the...bond or limit a bond to less than the full penal sum. (c) Date of execution....
27 CFR 26.69 - Strengthening bonds.
Code of Federal Regulations, 2010 CFR
2010-04-01
...Strengthening bonds. In all cases where the penal sum of any bond becomes insufficient...with the same surety to attain a sufficient penal sum, or give a new bond to cover the...amount of any bond to less than its full penal sum. Strengthening bonds shall show...
27 CFR 25.94 - Strengthening bonds.
Code of Federal Regulations, 2011 CFR
2011-04-01
...bonds. (a) Requirement. When the penal sum of the brewer's bond (calculated...give a strengthening bond in sufficient penal sum if the surety is the same as on the...bond or limit a bond to less than the full penal sum. (c) Date of execution....
27 CFR 26.69 - Strengthening bonds.
Code of Federal Regulations, 2011 CFR
2011-04-01
...Strengthening bonds. In all cases where the penal sum of any bond becomes insufficient...with the same surety to attain a sufficient penal sum, or give a new bond to cover the...amount of any bond to less than its full penal sum. Strengthening bonds shall show...
27 CFR 24.153 - Strengthening bonds.
Code of Federal Regulations, 2010 CFR
2010-04-01
...Strengthening bonds. In any instance where the penal sum of the bond on file becomes insufficient...with the same surety to attain a sufficient penal sum or give a new bond covering the...amount of either bond to less than its full penal sum. Strengthening bonds will show...
27 CFR 28.66 - Strengthening bonds.
Code of Federal Regulations, 2010 CFR
2010-04-01
...Strengthening bonds. In all cases where the penal sum of any bond becomes insufficient...with the same surety to attain a sufficient penal sum, or give a new bond to cover the...amount of any bond to less than its full penal sum. Strengthening bonds shall show...
27 CFR 19.246 - Strengthening bonds.
Code of Federal Regulations, 2010 CFR
2010-04-01
...Strengthening bonds. In all cases when the penal sum of any bond becomes insufficient...with the same surety to attain a sufficient penal sum, or give a new bond to cover the...amount of any bond to less than its full penal sum. Strengthening bonds shall show...
27 CFR 24.153 - Strengthening bonds.
Code of Federal Regulations, 2011 CFR
2011-04-01
...Strengthening bonds. In any instance where the penal sum of the bond on file becomes insufficient...with the same surety to attain a sufficient penal sum or give a new bond covering the...amount of either bond to less than its full penal sum. Strengthening bonds will show...
27 CFR 28.66 - Strengthening bonds.
Code of Federal Regulations, 2011 CFR
2011-04-01
...Strengthening bonds. In all cases where the penal sum of any bond becomes insufficient...with the same surety to attain a sufficient penal sum, or give a new bond to cover the...amount of any bond to less than its full penal sum. Strengthening bonds shall show...
19 CFR 113.11 - Bond approval.
Code of Federal Regulations, 2011 CFR
2011-04-01
...Duties 1 2011-04-01 2011-04-01 false Bond approval. 113.11 Section 113.11 Customs Duties...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY CUSTOMS BONDS Bond Application and Approval of Bond § 113.11 Bond...
19 CFR 113.11 - Bond approval.
Code of Federal Regulations, 2010 CFR
2010-04-01
...Duties 1 2010-04-01 2010-04-01 false Bond approval. 113.11 Section 113.11 Customs Duties...HOMELAND SECURITY; DEPARTMENT OF THE TREASURY CUSTOMS BONDS Bond Application and Approval of Bond § 113.11 Bond...
Oregon School Bond Manual. Sixth Edition.
ERIC Educational Resources Information Center
Oregon State Dept. of Education, Salem. Office of School District Services.
Given that purchasers of Oregon school bonds rely on recommendations of accredited bond attorneys, this document is designed to assist school districts in complying with state statutes regulating the issuance of school bond issues in order that attorney opinions may be favorable. Six initial steps toward a bond sale and Oregon laws regarding bonds…
Modelling matter: the nature of bonding
Haase, Markus
: Developing the model ionic bonding 18 Lesson 4: Developing the model covalent bonding 22 Lesson 5 is introduced, and is used to explain ionic, covalent and metallic bonding. The nature of bonding; using the new model to define ionic, covalent and metallic bonding. Communicative approach The sequence
Optimal Design and Tolerancing of Compressor Blades Subject to Manufacturing Variability
Wang, Qiqi
This paper presents a computational approach for optimal robust design and tolerancing of turbomachinery compressor blades that are subject to geometric variability. This approach simultaneously determines the optimal blade ...
Bio-inspired interfacial strengthening strategy through geometrically interlocking designs.
Zhang, Yuming; Yao, Haimin; Ortiz, Christine; Xu, Jinquan; Dao, Ming
2012-11-01
Many biological materials, such as nacre and bone, are hybrid materials composed of stiff brittle ceramics and compliant organic materials. These natural organic/inorganic composites exhibit much enhanced strength and toughness in comparison to their constituents and inspires enormous biomimetic endeavors aiming to synthesize materials with superior mechanical properties. However, most current synthetic composites have not exhibited their full potential of property enhancement compared to the natural prototypes they are mimicking. One of the key issues is the weak junctions between stiff and compliant phases, which need to be optimized according to the intended functions of the composite material. Motivated by the geometrically interlocking designs of natural biomaterials, here we propose an interfacial strengthening strategy by introducing geometrical interlockers on the interfaces between compliant and stiff phases. Finite element analysis (FEA) shows that the strength of the composite depends strongly on the geometrical features of interlockers including shape, size, and structural hierarchy. Even for the most unfavorable scenario when neither adhesion nor friction is present between stiff and compliant phases, the tensile strength of the composites with proper interlocker design can reach up to 70% of the ideal value. The findings in this paper would provide guidelines to the improvement of the mechanical properties of current biomimetic composites. PMID:23032427
. GO(Geometrical Optics), GTD(Geometrical Theory of Diffraction), PO(Physical Optics),
Myung, Noh-Hoon
. GO(Geometrical Optics), GTD(Geometrical Theory of Diffraction), PO(Physical Optics), PTD@kaist.ac.kr) ABSTRACT The IPO method has been used to analyze the scattering from the structures where propagation waves